فصلنامه مهندسی پزشکی زیستی
سال هشتم شماره 2 (تابستان 1393)

Gliomas are the most common primary neoplasm of the brain, varying histologically from low grade to high-grade. Perfusion-weighted MRI techniques have permitted the creation of cerebral blood volume (CBV) value, leading to the qualitative and quantitative assessment of tumor vascularity. This research aimed at assessing the rCBV and the ADC values in core and peritumoral areas glioma brain tumors and determining of significance rCBV of values i Alpha I In evaluating brain tumor. Ten patients with non-enhancing supratentorial gliomas were evaluated by diffusion weighted imaging (DWI) and standard dynamic susceptibility contrast-enhanced gradient echo during first pass of a bolus injection of contrast material before surgical resection. Six low-grade gliomas (WHO Grade II) and 4 high-grade gliomas (III, IV) were evaluated. Alpha Both the apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) values were calculated by a standard program on the solid portion of the tumor in the peritumoural area as well as contra lateral white matter. In perfusion, mean rCBVmax in high-grade and low-grade tumors were obtained (3.47±0.92), (2.37±0.49)-(1.66±0.68), (1.15±0.39) for core and peritumoral regions, respectively. In diffusion method, mean ADC in high-grade and low grade tumors were (0.53±0.07), (0.91±0.18)-(1.24±0.27), (1.007±0.33) for core and peritumoral regions, respectively. It was concluded that the values rCBVs ​​are important in determining the grade of tumor and we propose that perfusion weighted imaging be done for all patients before surgery.

MTDDS is an innovative treatment modality to completely tumor remission with no negative side effect. In this method functionalize magnetic nanoparticles are designed as the drug carrier to get the specific target in the body. Anticancer agents are bounded to magnetite nanoparticles with biocompatible starch coating suspended in the fluid. Now if they are injected intra-arterially near the target volume, they would be trapped at the target region via a local applied magnetic field with the high gradient near the target site. In this paper we have evaluated some nanoparticle trajectories with different size in order to evaluate the effect of the size on the efficiency of the magnetic drug targeting system.

Body cells, including mesenchymal stem cells are subject to a lot of mechanical forces. The type and magnitude of these forces are different in different physiological and pathological conditions. They cause a wide variety of cell responses and are able to change metabolisms and functions of the cell. Analysis of stem cell response to mechanical stimulation is very important in recognizing healthy and diseased condition of tissues and cells. Differentiation potential of mesenchymal stem cells to specialized cells makes them important cell sources in tissue engineering. In this study, atomic force microscopy and finite element method and used mechanical effects on a stem cellaresimulated which includes cell behavior due to strain andstress distributions in internal components of the cell. In this study, the ADINA software used to simulate mechanical behavior of the cell components (cell membrane, cytoplasm and nucleus) under a compressiveload. Results indicate mechanical response of stem cells in the body through which they can differentiate into bone cells and cartilage under compressive loads in the physiological range. This study has some considerable innovations as compared with the similar studies in the literature which is because of the kind of cells has been used (adipose-derived stem cells) as well as and also using precise material models for cell components based on the data extracted from laboratory tests for mechanical properties of the cell. Furthermore, this study can be considered as an important initial step for future studies on different patho-cells and analyzing their responses to mechanical loading using a similar method of this study to find new diagnostic methods. Also, it can be used to deepen pathological studies of the cells and the tissues.

Detection of tumors at an early stage is important for the diagnosis of cancer. Therefore, to detect cancer cells it is necessary to distinguish between metastases from normal cells at an early stage. Due to the large size and coverage necessary to prevent chemical reactions of the current contrast agents in the body, they are just applicable to the extracellular space. Due to the small size of nanoparticles in comparison to cells, it is possible for them to enter the cells. Therefore, these materials are used for molecular imaging. In this paper, variations in the external magnetic field (Tesla) due to magnetic nanoparticles in homogeneous tissue were studied by the finite element method. For this purpose, a simulation was performed in the presence of magnetic nanoparticles and without it. By the finite element method, conversion of differential and integral governing equations to simple and solvable equations that are numerically stable was made possible. The results obtained indicate that the external magnetic field is intensified by the presence of magnetic nanoparticles.

Insulin therapy for type 1 diabetes patients often causes high fluctuations in their blood glucose and hypoglycemic/hyperglycemic events. Closed loop control of blood glucose using artificial pancreas can improve life quality of patients. In this paper, physiological behaviour of the system has been modeled inversely using daily patient data acquired GIM simulator. Then, considering the delaed nature of the system, a novel adaptive control structure has been proposed for time-delayed systems, which is a combination of the model reference adaptive control with modified Smith Predictor. Due to extensive variability among patients in metabolism, an in silico trial consisting of 30 patients with random changes and sinusoidal oscillation in parameters of Dalla Man glucose-insulin model has been used to simulate the personal variability in the glucose control system. Performance of the proposed algorithm has been compared to the PID controller with Smith Predictor, based on the quantitative and qualitative indicatirs. Simulation results showthat the proposed controlscheme is effective in fasting conditions, meal disturbance rejection, and robustness against inter-patients variability.

Water molecules can be affected by magnetic fields due to their bipolar characteristics. In the present study an experimental maize field was irrigated with magnetically treated water. Tap water was passed through a locally designed alternative magnetic field generating apparatus (110 mT). The maize plants were irrigated by the magnetically treated waterfrom sowing to the seedling stage. Treatment with magnetically treated waterincreased the shoot and root lengths, fresh and dry weight of seedling (30%, 19.1%, 22% and 22%, respectively), compared with the control groups. The contents of photosynthetic pigments, total sugar and total protein of the leaves did not show significant differences between the treated plants and the control group. The ratio of Fv/Fm of seedling and growth parameters of second family were increased, compared to those of non-treated ones. The combined results suggested that the treatment of water a magnetic field with represents a plausible candidate for the mediation of MF effects on plant cells.

Two-dimensional gel electrophoresis (2DGE) is a basic and widely used method in proteomics. In this method, mixtures of proteins are separated due to the differences in their molecular weight and isoelectric points and a final image obtained from the separated protein spots is created. Due to the large number of the protein spots in a 2DGE image and the importance of separation of overlapping proteins, the image processing of these images is a complex process. 2DGE images pose various noises and artifacts such as cracks, staining artifacts, and streaks that affect the reliability of the analysis. In this work, we have proposed a novel spots filter based on the scale-space second order structural Hessian and its eigenvalues for enhancing and separating the spots from the background. Furthermore, in this work, 2DGE images have been segmented and the locations of the spots have been detected. To evaluate and compare the proposed method, we have implemented three

Otsu thresholding, Watershed transform, and the method proposed by Mylona et al. Based on the regional spot volume evaluation, the TPR and FPR of the proposed method are 78.6 and 14.9, the TPR and FPR of the Otsu method are equal to 71.4 and 25.7 percent, and the TPR and FPR of the Watershed algorithm are 53.9 and 8.1 percent, respectively. Also, in the spot counts evaluation, the Precision and TPR of the proposed method are equal to 83.6 and 81.1 percent, and the Precision and TPR of Otsu method are 65.4 and 78.3, respectively. The Watershed transform has detected the spots with Precision and TPR equal to 27.7 and 68.2 percent, and the Precision and TPR of the method proposed by Mylona et al. are 74.0 and 72.7 percent, respectively. The results reveal the accuracy and superiority of the proposed method.