110 research outputs found
Study of Modern Control Methodologies Applied to Tumor Growth under Angiogenic Inhibition
Cancer treatment is one of the most important research fields
of modern medicine.
In the last decades, targeted molecular therapies showed pr
osperous results. These treatments
achieve tumor regression with limited side-effects. Mathem
atical models were posed which
describe the dynamics of tumor regression under the applied
control. The current paper
investigates antiangiogenic therapy, which inhibits the t
umor to grow its own endothelial
capillaries and thus inhibits tumor to grow over a certain si
ze. Many different control approaches
were elaborated and published since the model formulation w
as posed. The aim of this paper
is to give an overview of these methods and results, and to rev
iew the work carried out by the
authors
Parameter optimization of H∞ controller designed for tumor growth in the light of physiological aspects
According to the fact that cancer diseases are leading causes of death all around the world, development of cancer fighting therapies is necessary. Beside the medical knowledge, there is an extra need for engineering approach to solve this complex problem. The aim of this paper is to design controller for tumor growth under angiogenic inhibition, which on the one hand minimizes the input signal as far as possible (in order to have less side effects and greater cost-effectiveness) and on the other hand results in appropriately low tumor volume. Since the model contains uncertainties and measurement noise, the controller was designed using modern robust control methodology. Choosing of the ideal system and the weighting functions were done in the light of physiological aspects
Model-based Angiogenic Inhibition of Tumor Growth using Adaptive Fuzzy Techniques
Fighting tumors is one of the most important problems of medical research. In this paper, antiangiogenic cancer therapy is investigated through its mathematical model.This tumor treatment method targets the endothelium of a growing tumor and belongs to the targeted molecular therapies.The aim of the therapy is not to eliminate the entire tumor,but to decrease the tumor to a minimal volume. An advantage of applying antiangiogenic treatment is that tumor cells show lower tendency of becoming resistant to the applied drugs.Adaptive fuzzy control is implemented for a simplified model to elaborate a control technique which is able to handle the effects of parameter perturbations and uncertainties while keeping the daily and total inhibitor inlet under a given limit
Magnetic Resonance imaging Assessment of Tumor Microvessels and Response to Antiangiogenesis Therapy
Magnetic resonance Imaging (MRI) is a diagnostic modality with high inherent contrast
resolution and multiplanar imaging capability. Advances in MR technology and image
processing have increased the utility and availability of this technique in the past two
decades. MRI has become one of the leading modalities in current diagnostic imaging,
combining soft tissue contrast with high anatomic and temporal resolution. MRI is now a
widely employed diagnostic method for the clinical evaluation of tumors.
One of the most recent applications of MRI is the investigation of angiogenesis using
dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). DCE-MRI represents
the acquisition of serial MR images before, during, and after the administration of an
intravenous contrast agent. The use of contrast enhancement in conjunction with magnetic
resonance imaging provides a means to evaluate tissue function, as well as morphology.
Tissue blood volume, blood flow, perfusion and capillary permeability represent indicators
of the status of the vasculature that can be investigated with DCE-MRI. Use of such
quantitation potentially allows tumors to be characterized in terms of pathophysiology
and to be monitored over time, during the course of therapeutic interventions. The
understanding of the angiogenesis process and the evaluation of new drugs that inhibit
or stimulate angiogenesis are directly related to the development of an imaging assay of
angiogenic activity. This method should provide functionally relevant and quantitative
images, should be high in spatial resolution, should sample the entire tumor and could be
repeated at frequent intervals.
DCE-MRI has grown in importance with the development of antiangiogenic and
neoadjuvant strategies for tumor therapy. Dedicated software makes it possible to
interpret imaging pharmacokinetics and aid the assessment of physiological parameters
such as capillary permeability and tissue perfusion. For instance, the permeability of
functional tumor microvessels can be assessed noninvasively by dynamic MRI of contrast
agent uptake in the tumor tissue (1-4). The analysis of contrast kinetics can be applied
to differentiate between a malignant and a benign lesion and to determine whether a
tumor is responding to treatment (5). It has been demonstrated that the permeability of
blood vessels correlates with the ability of the tumor to metastasize, and with its response
to treatment (6, 7). Thus, information concerning the status of vascular permeability
might help assessing the metastatic potential of tumors and predict the sensitivity to
chemotherapy or to antiangiogenic treatment
Radionuclide carriers for targeting of cancer
This review describes strategies for the delivery of therapeutic radionuclides to tumor sites. Therapeutic approaches are summarized in terms of tumor location in the body, and tumor morphology. These determine the radionuclides of choice for suggested targeting ligands, and the type of delivery carriers. This review is not exhaustive in examples of radionuclide carriers for targeted cancer therapy. Our purpose is two-fold: to give an integrated picture of the general strategies and molecular constructs currently explored for the delivery of therapeutic radionuclides, and to identify challenges that need to be addressed. Internal radiotherapies for targeting of cancer are at a very exciting and creative stage. It is expected that the current emphasis on multidisciplinary approaches for exploring such therapeutic directions should enable internal radiotherapy to reach its full potential
Novel anti-endothelial therapeutic strategies in malignant melanoma : the metronomic approach.
Treatment strategies for advanced malignancy remain limited in their success, despite major advances in the understanding of cancer aetiology and molecular biology. The incidence of many cancers, including melanoma, continues to rise, with a huge demand for therapies even if treatment goals are purely cytostatic. One particular therapeutic strategy is the metronomic (continuous and low) dosing of conventional chemotherapy. There is evidence to suggest that tumour vasculature is the main target of this dosing schedule resulting in an overall ‘non specific’ anti-angiogenic effect. It is now being studied in clinical trials alone and in combination with specific antiangiogenic agents.This thesis had two main aims: firstly to investigate the additive or synergistic antiendothelial effects of a number of conventional cytotoxic agents (Temozolomide, Paclitaxel, Vinorelbine, Etoposide, Carboplatin) in vitro given in a metronomic schedule in combination with a specific anti-angiogenic compound (Sorafenib) and a non-specific sompound (Combretastatin). The anti-proliferative, cytotoxic activities of the metronomic combinatorial schedules were assessed on microvascular endothelial cells and cancer cells using an MTT proliferation assay. Results confirmed significant (
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