31 documents found, page 1 of 4
Mathematics of aging: Diseases of the posterior segment of the eye
Ferreira, José Augusto; Oliveira, Paula de; Silva, Pascoal; Silva, RufinoThe changes caused by aging affect all body tissues. The vitreous humor, which fills the space between the lens and the retina, progressively liquefies and shrinks, eventually causing a posterior vitreous detachment. Retinal disorders caused by the breakdown of the blood retinal barrier are also associated with physiological aging. In this work a mathematical model of the pharmacokinetics of a drug eluted from ...
The influence of atherosclerotic plaques on the pharmacokinetics of a drug elut...
Ferreira, José Augusto; Gonçalves, Lino; Naghipoor, Jahed; Oliveira, Paula de; Rabczuk, TimonIn this paper the effect of plaque composition, on the accumulation of drug released by a drug eluting stent, is analyzed. The mathematical model is represented by two coupled systems of partial differential equations that describe the pharmacokinetics of drug in the stent coating and in the arterial wall. The influence of the stiffness and porosity of soft and hard plaques is studied. A case study based on opt...
Transdermal iontophoresis—A quantitative and qualitative study
Ferreira, José Augusto; Oliveira, Paula de; Pena, GonçaloThe use of enhancers to increase the drug molecules penetration into target tissues is a usual technique in drug delivery. In transdermal drug delivery, electric fields are often used to increase the drug transport through the skin. In this paper we study a drug delivery mechanism from a reservoir which is in contact with the skin. We assume that the drug transport in the coupled system is enhanced by a small e...
On the exponential decay of waves with memory
Ferreira, José Augusto; Oliveira, Paula de; Pena, GonçaloIn this paper we consider general linear damped wave equations with memory. We establish energy estimates that under the assumption of exponentially bounded kernels, induce exponential decaying solutions. Numerical waves that mimic their continuous counterpart are also introduced using a finite element approach.
Low-dose ionizing radiation induces therapeutic neovascularization in a pre-cli...
Ministro, Augusto; Oliveira, Paula de; Nunes, Raquel J.; Rocha, André dos Santos; Correia, Adriana; Carvalho, Tânia; Rino, José; Faísca, PedroAims: We have previously shown that low-dose ionizing radiation (LDIR) induces angiogenesis but there is no evidence that it induces neovascularization in the setting of peripheral arterial disease. Here, we investigated the use of LDIR as an innovative and non-invasive strategy to stimulate therapeutic neovascularization using a model of experimentally induced hindlimb ischemia (HLI). Methods and results: Afte...
A coupled non-Fickian model of a cardiovascular drug delivery system
Ferreira, José Augusto; Naghipoor, Jahed; Oliveira, Paula deA coupled non-Fickian model of a cardiovascular drug delivery system using a biodegradable drug-eluting stent is proposed. The numerical results are obtained using an implicit-explicit finite-element method. The influence of vessel stiffness on the transport of drug eluted from the stent is analysed. The results presented in this paper suggest new perspectives to adapt the drug delivery profile to the needs of ...
Tuning polymeric and drug properties in a drug eluting stent: A numerical study
Naghipoor, Jahed; Ferreira, José Augusto; Oliveira, Paula de; Rabczuk, TimonA two dimensional coupled nonlinear non-Fickian model for drug release from a biodegradable drug eluting stent into the arterial wall is studied. The influence of porosity and degradation of the polymer as well as the dissolution rate of the drug are analyzed. Numerical simulations that illustrate the kind of dependence of drug profiles on these properties are included.
Numerical and analytical study of drug release from a biodegradable viscoelasti...
Azhdari, Ebrahim; Ferreira, José Augusto; Oliveira, Paula de; Silva, PascoalA mathematical model to simulate drug delivery from a viscoelastic erodible matrix is presented in this paper. The drug is initially distributed in the matrix that is in contact with water. The entrance of water in the material changes the molecular weight, and bulk erosion can be developed depending on how fast this entrance is and how fast degradation occurs. The viscoelastic properties of the matrix also cha...
Analytical and numerical study of a coupled cardiovascular drug delivery model
Ferreira, José Augusto; Naghipoor, Jahed; Oliveira, Paula deA two dimensional coupled model of drug delivery in the cardiovascular tissue using biodegradable drug eluting stents is developed. Qualitative behavior, stability analysis as well as simulations of the model have been presented. Numerical results computed with an implicit–explicit finite element method show a complete agreement with the expected physical behavior.
Diffusion, viscoelasticity and erosion: Analytical study and medical applications
Azhdari, Ebrahim; Ferreira, José Augusto; Oliveira, Paula de; Silva, PascoalIn this paper diffusion through a viscoelastic biodegradable material is studied. The phenomenon is described by a set of three coupled partial differential equations that take into account passive diffusion, stress driven diffusion and the degradation of the material. The stability properties of the model are studied. Erodible viscoelastic materials, as biodegradable polymers, have a huge range of applications...