Journal of Biomedical Physics & Engineering
Volume:3 Issue: 2, Mar-Apr 2013

Various MTT assay methods are proposed to obtain the cell sur- vival parameters. Determining the survival curve characteristics of two cancerous cells of interest based on a common and a novel MTT assay method after exposing them to ionizing radiation. A common and a novel MTT assay method were used and compared for obtaining the F10B16 melanoma and 4T1 breast adenocarcinoma survivals after exposing them to ionizing radiation from a Co-60 machine. To obtain the survival parameters of the cells based on the common method, the cells were inoculated in 96-well plates. After irradiating the plates, the MTT assay was performed over the following days for a period of 8 days. Thereafter, the survival fraction was calcu- lated from a simple equation for every day from which the best day was selected. To acquire the cells’ survival parameters based on the novel method, extensive experi- ments were performed on a large number of samples. Then, the MTT assay was done in every day following various experimental treatments to acquire the exponential growth. Finally, the cells’ survivals were determined by measuring the space between relevant growing curves. At low doses (<4Gy) the two MTT assay methods indicated the same re- sults. However, at higher doses there were significant differences among the findings. Both of the MTT methods indicated that the cells’ responses are de- pendent on the dose levels used. Although the implementation of the common MTT assay method is simpler, the novel method seems to show more precise and reliable results at all levels of radiation doses.

Radiation-sensitive polymer gels are among the most promising three-dimensional dose verification tools and tissue-like phantom developed to date. The aim of this study is an investigating of percentage depth dose enhancement within the gel medium with used of conformal distribution gold nanoparticle as contrast agents by high atomic number material. In this work the normoxic polymer gel dosimeter MAGICA tissue- equivalence was first theoretically verified using MCNPX Monte Carlo code and experimentally by percentage depth dose curves within the gel medium. Then gold nanoparticles (GNPs) of 50nm diameter with different concentrations of 0.1mM, 0.2mM, and 0.4mM were embedded in MAGICA gel and irradiated by 18MV photon beam. Experimental results have shown dose increase of 10%, 2% and 4% in 0.1mM, 0.2mM and 0.4mM concentrations, respectively. Simulation results had good agreement in the optimum concentration of 0.1mM. The largest error between experi- mental and simulation results was equal to 9.28% stood for 0.4mM concentration. The results showed that the optimum concentration of gold nanoparticles to achieve maximum absorbed dose in both experimental and simula- tion was 0.1 mM and so it can be used for clinical studies.

The circle of Willis (COW) supports adequate blood supply to the brain. The cardiovascular system, in the current study, is modeled using an equivalent electronic system focusing on the COW. In our previous study we used 42 compartments to model whole car- diovascular system. In the current study, nevertheless, we extended our model by using 63 compartments to model whole CS. Each cardiovascular artery is modeled using electrical elements, including resistor, capacitor, and inductor. The MATLAB Simulink software is used to obtain the left and right ventricles pressure as well as pressure distribution at efferent arteries of the circle of Willis. Firstly, the normal operation of the system is shown and then the stenosis of cerebral arteries is induced in the circuit and, consequently, the effects are studied. In the normal condition, the difference between pressure distribution of right and left efferent arteries (left and right ACA–A2, left and right MCA, left and right PCA–P2) is calculated to indicate the effect of anatomical difference between left and right sides of supplying arteries of the COW. In stenosis cases, the effect of internal carotid artery occlusion on efferent arteries pressure is investigated. The modeling results are verified by comparing to the clinical observation reported in the literature. We believe the presented model is a useful tool for representing the normal operation of the cardiovascular system and study of the pathologies.

Whispering gallery modes (WGM) biosensors are ultrasensitive systems that can measure amount of adsorbed layer onto the micro-cavity surface. They have many applications including protein, peptide growth, DNA and bacteria detection, molecular properties measurements and specific interaction and drug table recognitions due to their high sensitivity, compact size and label free sensing mecha- nism. In this paper we investigate the effect of buffer solution on detection of specific biomolecules in WGM biosensors through its refractive index change. The propagation of electromagnetic waves in a dielectric microsphere is analyzed by solving Maxwell’s equations through proper boundary condition to find a concise relation for micro-cavity resonance shift. Analysis of the buffer solution’s refractive index effects on detection of BSA by WGM biosensors are presented and it was shown that even a very small change in the refractive index of buffer solution can affect the biosensor wavelength shift and the sensitivity of biosensors. This study opens up a discussion in biosensor sensitivity based on true and reliable performance of the buffer solution through its accurate determina- tion of refractive index and behavior.To avoid expensive methods of enhancing sen- sitivity, one can improve the sensitivity of WGM biosensor to some extent, by means of using proper buffer solution.

Autoregulation of blood flow is a marvelous phenomenon balanc- ing blood supply and tissue demand. Although many chemically-based explanations for this phenomenon have been proposed and some of them are commonly used today, biomechanical aspects of this phenomenon was neglected. The biomechanical aspect provides insights to us to model vessel diameter changes more precisely and comprehensively. One important aspect of autoregulation phenomenon is temperature changes of the tissue resulted from tissue metabolism. We hypothesize that tempera- ture changes can affect the mechanical properties of the vessel wall leading to vessel diameter changes during autoregulation. Mechanical modeling of vessel diameter changes can also be useful to explain other phenomena in which the vessel diameter changes in response to temperature alterations. Through the mechanical modeling of any vessel, the analysis of temperature-induced changes in vessel diameter can be done more precisely.