Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Vahid Khandan; Bahar Firoozabadi; Mohammad Saeid Saeidi
Volume 8, Issue 3 , September 2014, , Pages 229-239
Abstract
A hallmark of Alzheimer disease (the most common type of dementia in the elderly) is the aggregation and deposition of toxic species ranging from small soluble oligomers to insoluble fibril plaques of Amyloid-Beta protein originates from the cleavage of APP by Beta and Gama Secretase (Amyloid Hypothesis). ...
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A hallmark of Alzheimer disease (the most common type of dementia in the elderly) is the aggregation and deposition of toxic species ranging from small soluble oligomers to insoluble fibril plaques of Amyloid-Beta protein originates from the cleavage of APP by Beta and Gama Secretase (Amyloid Hypothesis). An attractive therapeutic approach to treat AD is to identify small ligands capable of binding to A-Beta monomers and reverse its amyloidosis process. Here, a peptide drug having the sequence of GLMVG which has been derived from the C-terminal of A-Beta was used as breaker for a monomer of Beta sheet rich structure. The combination of Docking and Molecular Dynamics methods were used for simulation of drug-receptor interaction. This simulation implied that pentapeptide altered secondary structure of A-Beta monomer and declined its stability. This study proved that pentapeptide is capable to reverse Beta-sheet formation and can be considered as an AD drug in other preclinical studies.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Fariba Ganji; Fateme Hoobakht; Farzane Ghasemi Tahrir; Ebrahim Vasheghani-Farahani
Volume 8, Issue 3 , September 2014, , Pages 249-260
Abstract
Somanis one of the strongest nerve agents and treatment of poisoning with Soman is difficult and time-critical. Pyridostigmine bromide is an inhibitor of cholinesterase used for protecting against toxicity by Soman. In this study, a new injectable thermosensitive sustained release dosage form of pyridostigmine ...
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Somanis one of the strongest nerve agents and treatment of poisoning with Soman is difficult and time-critical. Pyridostigmine bromide is an inhibitor of cholinesterase used for protecting against toxicity by Soman. In this study, a new injectable thermosensitive sustained release dosage form of pyridostigmine bromide was achieved by chitosan/glycerolphosphate solution. In this study, thermosensitivity and rheological properties of chitosan solution (2% w/v) in aqueous hydrochloric acid (0.1 molar) with different percent of glycerolphosphate salt as well as the release profile of pyridostigmine bromide have been investigated. It was observed that increasing the glycerolphosphate salt concentration would increase the pH of chitosan solution, while decrease its gelation time and loss or storage modulus. It was also observed that glycerolphosphate salt concentration has direct effect on hydrogel thermoreversibility. The presented results indicated that hydrogel containing 2% w/v of chitosan and 16% w/v of glycerolphosphate salt could sustain the delivery of pyridostigmine bromide, through Fickian diffusion, up to four days.
Tissue Engineering
Zahra Saghaei Noosh Abadi; Atefe Aghajani; Mohammad Haghpanahi
Volume 7, Issue 1 , June 2013, , Pages 1-11
Abstract
We introduce how we may produce an experimental phantom for modeling the mechanical properties of soft tissue. Gelatin materials are used to construct the phantom. Our phantom comprises of two different types of tissue; tumor and background normal tissue. Weight ratio of the dry gelatin and deionized ...
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We introduce how we may produce an experimental phantom for modeling the mechanical properties of soft tissue. Gelatin materials are used to construct the phantom. Our phantom comprises of two different types of tissue; tumor and background normal tissue. Weight ratio of the dry gelatin and deionized water are obtained for producing the young’s modulus of 21 kPa and 102 kPa for the normal tissue and tumor, respectively. This phantom is used in ultrasound elastography with external excitation less than 5%.
Saeed Hesaraki; Masoud Hafezi Ardakani; Kolsoum Rajabi Monavar; Hosein Mohammadi
Volume 7, Issue 3 , June 2013, , Pages 201-207
Abstract
In this research, effect of temperature and calcium to phosphorus (Ca/P) ratio of raw materials on the type and the amounts of formed phases were investigated by solid state method. Calcium carbonate and dicalcium phosphate were provided as raw materials and mixed with different percentages in a way ...
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In this research, effect of temperature and calcium to phosphorus (Ca/P) ratio of raw materials on the type and the amounts of formed phases were investigated by solid state method. Calcium carbonate and dicalcium phosphate were provided as raw materials and mixed with different percentages in a way that final (Ca/P) ratio was between 1.50 to 1.67 in different batches. Then each of these mixtures was heated at temperatures of 800 to 1200 ° C for 3 hours. Phases were identified with XRD technique and quantitative assessment of phases was evaluated by RIR method and Chung relation. Results showed that in all relations and desired temperatures sintered below 1100 ° C beta tri-calcium phosphate is the dominant phase and hydroxyapatite present as second phase in the composition. In samples which sintered at 1200° C, beta TCP is transferred significantly to alpha TCP. In samples with Ca/p ratio: 1.62, 1.67, hydroxyapatite is dominant phase at 1200° C.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Zohre Goodarzi; Bahman Ebrahimi Hosein zadeh; Morteza Maghrebi; Alireza Fakhari Zavareh; Mohammad Barshan; Hosein Shaki
Volume 7, Issue 2 , June 2013, , Pages 133-141
Abstract
Nicotine can be measured electrochemically using Cu nanoparticles and CNT-modified glassy carbon electrode. The slow electrochemical oxidation makes it difficult to measure the concentration of nicotine electrochemically using normal electrodes.To improve the oxidation rate, different mediators and chemically ...
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Nicotine can be measured electrochemically using Cu nanoparticles and CNT-modified glassy carbon electrode. The slow electrochemical oxidation makes it difficult to measure the concentration of nicotine electrochemically using normal electrodes.To improve the oxidation rate, different mediators and chemically modified electrodes have been used. In this experiment, concentration of nicotine in aqueous solution was determined using MWCNT-modified glassy carbon electrode in presence of copper nanoparticles (Cu NPs) as mediator. For this purpose, the glassy carbon electrode (GCE) was modified with suspended MWCNT in dimethylformamaide and Cu NPs was electrochemically deposited on MWCNT-GCE subsequently. Also, experimental parameters affecting the deposition of Cu NPs on MWCNT-GCE such as cycles, copper salt concentration and scan rate were found to be optimum at 20 cycles, 1.75 μmol L-1 and 100 mVs-1 respectively. Finally, the modified electrode was characterized by cyclic voltammetry and successfully used to measure the concentration of nicotine in aqueous solution.
Biomechanics of Bone / Bone Biomechanics
Masume Khaghani; Zahra Golniya; Ali Doostmohammadi
Volume 6, Issue 1 , June 2012, , Pages 1-7
Abstract
The aim of this work was evaluating of zirconia nanoparticles’ effect on physical and mechanical properties of dental glass ionomer cements (GICs). Ceramic part of GIC was prepared using melting method and zirconia nanoparticles were added to GIC in 1, 3 and 5 weight percent. Characterization tests ...
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The aim of this work was evaluating of zirconia nanoparticles’ effect on physical and mechanical properties of dental glass ionomer cements (GICs). Ceramic part of GIC was prepared using melting method and zirconia nanoparticles were added to GIC in 1, 3 and 5 weight percent. Characterization tests and compressive strength evaluation of nanocomposite samples were carried out. The XRD results showed that the prepared ceramic part of GIC was completely amorphous and can be used as the matrix of composite. The result of XRF showed that the chemical composition of ceramic part of GIC was similar to expected composition. Also the results of mechanical properties determination analysis showed that the addition of zirconia nanoparticles to GIC could improve the compressive strength. The maximum of this strength obtained using 1% wt of GIC in zirconia composite. Increasing the nanoparticles content resulted in decrease of compressive strength but the strength of composite with any composition was more than the strength of control sample. According to the results of this study, the most proper composite was the one containing1%wt zirconia nanoparticles.
Bioelectromagnetics
Maryam Sadri; Parviz Abdolmaleki; Saeed Abroun; Bahare Beiki; Fazel Samani
Volume 6, Issue 2 , June 2012, , Pages 91-98
Abstract
The Mesenchymal Stem cells derived from human newborn cords were cultured and exposed to a 24mT Static magnetic field for 24 hours. The viability percentage and the cell cycle progression was then investigated in exposed samples and the obtained results was compared with the control samples. The results ...
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The Mesenchymal Stem cells derived from human newborn cords were cultured and exposed to a 24mT Static magnetic field for 24 hours. The viability percentage and the cell cycle progression was then investigated in exposed samples and the obtained results was compared with the control samples. The results clearly demonstrated a significant reduction of cell viability due to the exposure of 24 hours of SMF and post-exposure cultures within the time frames of 36,48,60 hours. The cell development through the cell-cycle, also verified this finding, however, 72 hours of post-exposure culture, significantly leveled off the drop in viable stem cell rates.
Nano-Biomaterials
Shekufe Borhan; Saeed Hesaraki
Volume 6, Issue 3 , June 2012, , Pages 163-168
Abstract
Bioactive glasses with different compositions have been extensively used as substitute for defective bones. Injectable biomaterial is important in clinical applications that involve defects with limited accessibility or when using minimally invasive surgical techniques. In this study bioactive glass ...
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Bioactive glasses with different compositions have been extensively used as substitute for defective bones. Injectable biomaterial is important in clinical applications that involve defects with limited accessibility or when using minimally invasive surgical techniques. In this study bioactive glass nano-powder was synthesized by acid-base catalyzed sol-gel process and used as solid phase of injectable non-setting pastes. Morphological characteristics of powder were found by TEM. To prepare paste the powder was mixed with hyaluronic acid and polyvinyl alcohol solutions. Stability of pastes was determined by soaking in simulated body fluid. Rheological behaviours of paste in both rotation and oscillation modes were also measured. The results showed that particle size of glass powder was 20-30 nm. According to rheometry, these nano composites exhibited non-Newtonian shear thinning behaviour. By adding polyvinyl alcohol more stable paste with increased hysteresis loop area is obtained. The oscillatory tests revealed that these pastes were viscoelastic with more elastic character. The biocomposite can potentially be used as bioactive paste for the treatment of hard and even soft tissues.
Biomechanics of Bone / Bone Biomechanics
Hoda Salemi; Ali Asghar Behnamghader; Mohammad Reza Baghaban Eslaminejad; Mohammad Ataei
Volume 6, Issue 4 , June 2012, , Pages 249-255
Abstract
Collagen and Hydroxyapatite (HA) nanoparticles are significant constituent of the natural bone. In this study, the effect of collagen on the morphological and phase characteristics of calcium phosphate nanoparticles was investigated. The synthesis reaction was initiated by mixing H3PO4 as phosphorous ...
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Collagen and Hydroxyapatite (HA) nanoparticles are significant constituent of the natural bone. In this study, the effect of collagen on the morphological and phase characteristics of calcium phosphate nanoparticles was investigated. The synthesis reaction was initiated by mixing H3PO4 as phosphorous source and CaCl2 as calcium source in presence of Collagen Type 1. Collagen concentration in suspension and Ca to P ratio was 1% and 1.67 respectively. The morphology and structure of samples (with collagen and without collagen), heat treated at 600 0C were characterized by X-Ray diffraction (XRD), Fourier transformation infrared (FTIR) and Scanning electron microscopy (SEM). More fine and flake-like shape particles were observed in the SEM images of sample synthesized in the presence of collagen compared to the control sample which was constituted of larger granular particles. The XRD results revealed the powders were composed of hydroxyapatite and octacalcium phosphate and the sample synthesized in the presence of collagen was less crystalline. The amide bands of collagen and P-O and OH characteristic peaks were identified in FT-IR spectra.
Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 1 , June 2012, , Pages 9-15
Abstract
NiTi shape memory alloy cannot provide all the clinical requirements of an implant due to the high nickel content and bio-inert surface. Thus, its surface is coated by bio-ceramics such as hydroxyapatite (HA) in different methods in order to improve biocompatibility and bioactivity. In the present ...
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NiTi shape memory alloy cannot provide all the clinical requirements of an implant due to the high nickel content and bio-inert surface. Thus, its surface is coated by bio-ceramics such as hydroxyapatite (HA) in different methods in order to improve biocompatibility and bioactivity. In the present study, a bio-active coating of HA using electrophoretic deposition technique was created on the surface of NiTi alloy to act as a barrier and prevent the diffusion of nickel ions in to the body fluid. A suspension was prepared by n-butanol as solvent and triethylenamine as dispersant. Coatings were deposited at different voltage of 40, 60 and 80 V for duration of 120s on the cathode. Then coated samples were sintered at 800 °C under argon atmosphere for 2 hrs. Evaluation of coatings was performed by X-ray diffraction techniques (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Bioactivity and corrosion behavior of HA coatings was studied within simulated body fluid (SBF) environment. The results showed, the sample coated at 60 V is dense, uniform, owing proper corrosion resistant, and also the ability for nucleation and growth of apatite layer in SBF.
Bioelectromagnetics
Samane Sedighi; Keyvan Keramati; Ali Safari-Varyani; Ahmad Nikpey
Volume 6, Issue 2 , June 2012, , Pages 99-106
Abstract
Exposure to magnetic fields can effect on the learning and memory. The protective effect of saffron extract on memory consolidation disorders in rats exposed to magnetic fields was investigated. 120 male Wistar rats in 12 groups exposed to magnetic field For 5 days with intensity 2.5 tesla for 1, 3 and ...
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Exposure to magnetic fields can effect on the learning and memory. The protective effect of saffron extract on memory consolidation disorders in rats exposed to magnetic fields was investigated. 120 male Wistar rats in 12 groups exposed to magnetic field For 5 days with intensity 2.5 tesla for 1, 3 and 5 hour and protective effects of saffron extract with doses of 125 mg, 200 mg and 300 mg (P ≤0.05) compared to the control group by passive avoidance learning method in shuttle box. One hour exposure with magnetic field had no effect on the rats’ memory consolidation (P ≤0.05). Increase exposure time to 3 and 5 hours had a memory consolidation Impairment compared to the control group (P ≤0.05). Administered rats with 300 mg Inter peritoneal saffron extract improved memory consolidation (P ≤0.05) compared to the control group. Exposure to magnetic fields 2.5 mT, 50 Hz impair memory consolidation. Saffron aqueous extract at a dose of 300 mg per kg may have a protective effect and be improvement consolidation impairments.
Bioelectromagnetics
Susan Kohzad; Bahram Bolouri; Farnaz Nikbakht; Zahra Kohzad
Volume 6, Issue 2 , June 2012, , Pages 107-111
Abstract
There is a growing public concern that the extremely low frequency (ELF) range of the environmental electromagnetic fields may have adverse biological effects. In this frequency range, 217Hz is the modulating signal being used in Global System of Mobile. This study investigated the possible effects of ...
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There is a growing public concern that the extremely low frequency (ELF) range of the environmental electromagnetic fields may have adverse biological effects. In this frequency range, 217Hz is the modulating signal being used in Global System of Mobile. This study investigated the possible effects of 217 Hz pulsed electromagnetic field on the anxiety and the cortisol level in rats. Twenty four male Wistar rat (200 - 250 g) were randomly grouped into test, sham and control. Using a pair of Helmholtz coil system, the test group was exposed to a uniform pulsed EMF of 200µT intensity for 4 h/day for 21 days. A similar procedure with no field was repeated for the sham group. All groups were tested in an `Elevated- plus` maze system. Then via the heart puncture scheme, the blood samples were collected. The serum cortisol levels were evaluated using ELISA method.The ANOVA test revealed no significant differences for the Elevated- plus maze test. Serum cortisol level was significantly higher in test group compared to the control group.These findings were in consistent with the work of others indicating that low frequency band of EMF might not have any effect on the anxiety but it increases the cortisol levels as a stress marker.
Nano-Biomaterials
Zeynab Fereshteh; Mohammad Hossein Fathi; Reza Mozaffarinia
Volume 6, Issue 3 , June 2012, , Pages 177-193
Abstract
The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, ...
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The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, applied voltage, nozzle to collector distance and content of ceramic. It was shown that the diameter size of fibers decreased by adjusting the viscosity and conductivity solution. Optimal samples were studied with transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA). According to TEM and the X-ray maps of the scaffolds, Mg-FA particles were homogeneously dispersed into the nanofibers without any agglomeration. It is noteworthy that was not any surfactant in this study. Also results of XRD show no chemical reactions between polymeric solution components. Mechanical properties of the scaffolds were also evaluated. Results showed that tensional strength of scaffolds and also thermal stability increased by increasing the weight ratio of nanoparticles up to 5 wt. %.
Genetic Engineering / Genetic Modification / Genetic Manioulation
Ayatollah Rezaei; Faeze Ghanati; Mehrdad Behmanesh
Volume 6, Issue 2 , June 2012, , Pages 113-122
Abstract
In this study cell growth, some physiological parameters, production of Taxol and gene expression in cell culture of hazel under effect of the magnetic field were investigated. Cells in suspension culture were treated by a 30 mT static magnetic field on days 8-11 after subculture and 4 hours each day. ...
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In this study cell growth, some physiological parameters, production of Taxol and gene expression in cell culture of hazel under effect of the magnetic field were investigated. Cells in suspension culture were treated by a 30 mT static magnetic field on days 8-11 after subculture and 4 hours each day. The results showed that while the growth rate and viability of cells weren’t affected by the magnetic field but membrane lipid peroxidation rate and H2O2 production increased. Activity of phenylalanine ammonia lyase, polyphenol oxidase and peroxidase enzymes was increased by the magnetic field compared with control. Production of phenolic compounds and Taxolin treated cells showed an increase compared to those of control cells. Magnetic field increased intracellular Taxol more than extracellurTaxol, and in treated cultures total taxol production was 2.9-fold compared to control culture. Gene expression of 1- deoxy -D- xylulose -5 - phosphate reductoisomerase involved in producing Taxol precursors and in its biosynthesis was also increased in treated cells compared to control. It appears that magnetic field by stimulating cell defense responses and inducing gene expression involved in Taxol biosynthesis has resulted in improved its production.
Yaser Rezaei Moghaddam; Seyed Mehdi Rezaei; Mahnaz Shamshirsaz; Mohammad Zareinejad; Mohammad Reza Dehghan
Volume 6, Issue 4 , June 2012, , Pages 299-305
Abstract
In vitro fertilization (IVF) is a solution to overcome the problem of infertility of couples .Lately with the development of technology and using robotic systems, telesurgery systems are used in order to increase the accuracy, better control of needle movement and preventing injury to the ovum cell while ...
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In vitro fertilization (IVF) is a solution to overcome the problem of infertility of couples .Lately with the development of technology and using robotic systems, telesurgery systems are used in order to increase the accuracy, better control of needle movement and preventing injury to the ovum cell while injection in IVF. To provide better control of injection, haptic systems are used. In this study, a haptic system is designed with virtual reality environment in order to perform In vitro fertilization. For modeling of injection force, point-load model is utilized. A mass-spring model is used to simulate cell deformation during insertion. Simulation results have a good conformity with related researches.
Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 3 , June 2012, , Pages 231-238
Abstract
In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized ...
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In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized using triethylenamine as dispersant. Surface characteristics, adhesion strength, stability and bioactivity of the composite coating were subsequently studied. EDX examination of the composite coating surface revealed homogeneous dispersion of carbon nanotubes all over coating. Also, the bonding strength of composite coating was found to be about 24 MPa. Compared to NiTi sample coated with hydroxyapatite and coated with hydroxyapatite/carbon nanotubes, the bode and nyquist plots of NiTi samples with hydroxyapatite/carbon nanotubes composite coating suggested that the composite coating was chemically more stable and provided corrosion resistance for NiTi SMA. In-vitro bioactivity test in SBF showed that the presence of CNTs in HA/CNTs composite coating does not have negative effect on ability of apatite formation.
Arghavan Farzadi; Mehran Solati Hashjin; Farhad Bakhshi; Alie Aminian
Volume 5, Issue 3 , June 2011, , Pages 206-213
Abstract
Using microwave irradiation in microwave-assisted synthesis method is a new approach employed to decrease synthesis time and to form more homogenous structures of biphasic calcium phosphate bioceramics. In this research, the microwave assisted synthesis and characterization of biphasic calcium phosphate ...
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Using microwave irradiation in microwave-assisted synthesis method is a new approach employed to decrease synthesis time and to form more homogenous structures of biphasic calcium phosphate bioceramics. In this research, the microwave assisted synthesis and characterization of biphasic calcium phosphate nanopowders have been studied. The phase transformation, chemical components, morphology and particle size were characterized by X-Ray Diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the use of microwave led to improve crystallinity and the crystallite size increases from 16 nm to 27 nm. Also the amount of hydroxyapatite phase in biphasic calcium phosphate changed in the range of 5% to 17%. The prepared sample was put in Simulated Body Fluid (SBF).The pH of the solution was decreased in the present of beta-tricalcium phosphate showed its biodegradable behavior. Also the nucleation and growth of hydroxyapatite particles on TCP produced by microwave -assisted synthesis method changed to be rod like in SBF solution.
Sahba Mobini
Volume 5, Issue 2 , June 2011, , Pages 151-159
Abstract
Silk fibroin is fibrous proteins with excellent mechanical properties which are produced by wide group of animals such as Bombyx Mori. Silk fibroin with specific molecular structure can be processed into a diverse set of morphologies. Additionally, biotechnologically produced silk proteins will allow ...
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Silk fibroin is fibrous proteins with excellent mechanical properties which are produced by wide group of animals such as Bombyx Mori. Silk fibroin with specific molecular structure can be processed into a diverse set of morphologies. Additionally, biotechnologically produced silk proteins will allow the preparation of a new generation of protein-based bio-polymeric materials with programmed properties for a wide variety of exciting medical applications. In this study, silk protein was extracted from Bombyx Mori’s cocoons and evaluated by FTIR and XRD methods. Results showed sharp amide peaks in 1655 cm-1 and 1530 cm-1 wavelength in FTIR spectrum pattern confirming existence of fibroin. SEM images of the fibers showed continuous fibers with cross-section between 14 to 24 μm. Biocompatibility tests were carried out through seeding osteoblasts cell line G292 on 2D film as well as fibers. Adhesion and proliferation of osteoblasts were investigated by MTT assay which showed no cytotoxicity. Therefore, fibroin appears to be remarkable material for prospect application in biomedicine.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Mohammad Koohimoghadam; Adel Torkamaan Rahmani
Volume 5, Issue 4 , June 2011, , Pages 333-351
Abstract
Discovery of new drugs and study of their side effects has been an important research field in recent years. Because of direct effect of the pharmaceutical products on human health usually the drug design projects are challenging and technically demanding. The incorporation of computer simulations into ...
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Discovery of new drugs and study of their side effects has been an important research field in recent years. Because of direct effect of the pharmaceutical products on human health usually the drug design projects are challenging and technically demanding. The incorporation of computer simulations into drug design projects is one of the best ways to optimize drugs' potency. In this approach, researchers try to find the best interaction between protein structure and drug in a virtual environment; this procedure is called "molecular docking". The molecular docking problem can be considered as a search problem. The search space in this problem is defined with all possible protein-ligand interactions and the best interaction is the solution of problem. In this paper, a new approach for finding the best interaction is proposed. The proposed method is based on opposition based differential evolution algorithm. Also the proposed method is enhanced by a local search algorithm and a pseudo-elitism operator. Like other metaheuristic algorithms, our method uses a population of possible solution and AutoDock scoring function is used to evaluate each vector in the population. Six different protein-ligand complexes are used to verify the efficiency of the proposed algorithm. The experimental results show that the proposed algorithm is more robust and reliable than other algorithms such as simulated annealing and Lamarckian genetic algorithm.
Biological Computer Modeling / Biological Computer Simulation
Mahmoud Amiri; Fariba Bahrami; Mahyar Janahmadi
Volume 4, Issue 2 , June 2010, , Pages 83-96
Abstract
Based on the neurophysiologic findings, astrocytes provide not only structural and metabolic supports for the nervous system but also they are active partners in neuronal activities and synaptic transmissions. In the present study, we improved two biologically plausible cortical and thalamocortical neural ...
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Based on the neurophysiologic findings, astrocytes provide not only structural and metabolic supports for the nervous system but also they are active partners in neuronal activities and synaptic transmissions. In the present study, we improved two biologically plausible cortical and thalamocortical neural population models (CPM and TCPM), which were developed previously by Suffczynski and colleagues, by integrating the functional role of astrocytes in the synaptic transmission in the models. In other words, the original CPM and TCPM are modified to integrate neuronastrocyte interaction considering the idea of internal feedback proposed by Iasemidis and collaborators. Using the modified CPM and TCPM, it is demonstrated that healthy astrocytes provide appropriate feedback control for regulating the neural activities. As a result, we observed that the astrocytes are able to compensate for the variations in the cortical excitatory input and maintain the normal level of synchronized behavior. Next, it is hypothesized that malfunction of astrocytes in the regulatory feedback loop can be one of the probable causes of seizures. That is, pathologic astrocytes are not any more able to regulate and/or compensate the excessive increase of the cortical excitatory input. Consequently, disruption of the homeostatic or signaling function of astrocytes may initiate the hypersynchronous firing of neurons. Our results confirm the hypothesis and suggest that the neuronastrocyte interaction may represent a novel target to develop effective therapeutic strategies to control seizures.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Nadia Naghavi; Amene Sazgarnia; Mohammad Hossein Miranbaygi
Volume 4, Issue 3 , June 2010, , Pages 209-218
Abstract
Today, the idea of photodynamic therapy (PDT) is considered as one of the fundamental basis of the new cancer treatment methods. One of the important issues in the application of this therapy is choosing the optimal dosimetry method. At best, PDT dosimetry should be done based on estimation of the accumulated ...
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Today, the idea of photodynamic therapy (PDT) is considered as one of the fundamental basis of the new cancer treatment methods. One of the important issues in the application of this therapy is choosing the optimal dosimetry method. At best, PDT dosimetry should be done based on estimation of the accumulated singlet oxygen dose within the target tissue and comparison with the threshold value to ensure the efficacy of the treatment. In order to estimate the accumulated singlet oxygen level within the tissue, the most appropriate method is modeling the process of treatment. In this context, it is necessary to obtain enough information about the drug concentration within the target tissue, the amount of light absorbed by the drug, the amount of oxygen into the tissue, and the interactions between them that produce singlet oxygen. In this study modeling and simulation of the photobleaching has been investigated, considering the importance of the level of drug concentration in the target tissue which would be decreased by photobleaching. Simulation was done with Matlab software. A Comparison of simulation results with those of experimental methods showed that in the state of non-uniform drug distribution, simulation follows experimental results at the initial phase of rapid decline of drug concentration.
Maryam Parviz; Mohammad Rabiee; Mohammad Ali Shokrgozar; Fathollah Moztarzadeh; Farzad Yousefi Gharebaghi; Mahdis Shayan; Mohammad Reza Tahriri
Volume 3, Issue 2 , June 2009, , Pages 89-97
Abstract
A great deal of attention has been drawn to the colloidal chemistry based semiconductor nanocrysallites, also known as quantum dots (QDs). Because of the strong quantum confinement, quantum dots have unique size-dependent optical properties, which are much more superior to the conventional organic fluorescence ...
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A great deal of attention has been drawn to the colloidal chemistry based semiconductor nanocrysallites, also known as quantum dots (QDs). Because of the strong quantum confinement, quantum dots have unique size-dependent optical properties, which are much more superior to the conventional organic fluorescence materials. In addition, strong chemical resistant makes inorganic semiconductor QDs an ideal candidate for next-generation of bio-labels and other biomedical applications. This study presents a synthesize method of high quality biocompatible CdSe QDs in aqueous solution by using gelatin as inhibitor. A thin ZnS layer was grown on CdSe QDs, forming a CdSe/ZnS core/shell structure, to improve the photoluminescence. The optical properties of the QDs were characterized by photoluminescence spectra. The stability of CdSe/ZnS QDs in aqueous solution has been improved with capping in mercaptosuccinic acid (MSA) groups. PAGE test results show that carboxylic groups of MSA have interacted with NH2 agent of CD20 antibodies. We evaluate the in vitro efficiency of the luminescence of the bioconjugated QDs to kill Raji cells. Raji cells have anti-CD20 which can especially connect to CD20-QDs. In conclusion, we found that CD20-CdSe/ZnS bioconjugated QDs with different concentration 50-250 µg/mL which have been exited at 400nm in 2h intervals can result in Raji cells death. This study shows the potential of CdSe/ZnS for cancer treatment.
Biopolymers
Hadis Bandegani; Saeed Hesaraki; Masoud Alizadeh
Volume 3, Issue 2 , June 2009, , Pages 99-109
Abstract
The aim of the present paper is to investigate the effect of incorporating various amounts of strontium ions (0.19 - 2.23 wt%) into calcium sulfate bio ceramics on the physical, structural properties and in vitro bioactivity and compare these properties with those of a pure calcium sulfate dehydrate ...
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The aim of the present paper is to investigate the effect of incorporating various amounts of strontium ions (0.19 - 2.23 wt%) into calcium sulfate bio ceramics on the physical, structural properties and in vitro bioactivity and compare these properties with those of a pure calcium sulfate dehydrate (gypsum) as control. Strontium-doped gypsum (Sr-gypsum) was obtained by mixing calcium sulfate hemihydrates powder and solutions of strontium nitrate followed by washing the specimens with distilled water for the removal of residual salts. Gypsum was the only phase found in the composition of both pure and Sr-gypsum meanwhile a shift into lower diffraction angles was observed in the x-ray diffraction patterns of doped specimens. The Sr-doped sampled exhibited higher compressive strength and lower solubility than pure gypsum. Microstructure of all gypsum specimens had been composed of many rod-like small crystals entangled to each others with more elongation and higher thickness in the cases of Sr-gypsum. EDXA pattern of Sr-gypsum showed the presence of calcium and sulfur ions as the main elements of gypsum as well as slight amount of strontium ion. A continuous release of strontium was observed from the Sr-gypsum after soaking in simulated body fluid for 14 days. Proliferation rate of cultured osteoblasts and higher alkaline phosphatase activity on doped samples was better compared to pure gypsum.
Mehrnoush Zare; Jafar Khalil Allafi; Behnam Amin Ahmadi; Seyed Mohammad Mehdi Hadavi
Volume 3, Issue 2 , June 2009, , Pages 111-118
Abstract
Ni-Ti shape memory alloys display unique properties such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior. They also are suitable materials for medical applications. In spite of high Ni content (above 50%) of Ni-Ti shape memory alloys, these materials represent ...
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Ni-Ti shape memory alloys display unique properties such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior. They also are suitable materials for medical applications. In spite of high Ni content (above 50%) of Ni-Ti shape memory alloys, these materials represent good biocompatibility due to formation of Titanium oxide (TiO2) passive layer. Although TiO2 passive layer in these alloys can prevent releasing nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a Ni-Ti shape memory alloy with nominal composition of 50.7 atom% Ni was produced by vacuum induction melting (VIM) process. Homogenization treatments of samples were performed at 1050C for 24 hours. Microstructure and chemical composition of specimens were analyzed. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. In order to determine the amount of released Ni, the solution after potentiostatic tests was analyzed by atomic absorption spectroscopy. The samples after corrosion tests were investigated using Scanning Electron Microscopy (SEM). Furthermore corrosion products were analyzed by X-Ray Diffraction (XRD). Results indicate that the breakdown potential of the Ni-Ti alloy in NaCl 0.9% solution is higher than that in ringer solution. Topographical evaluations show that corrosion products are nearly the same in all samples.
Ali Nemati; Abdorreza Sheikh Mehdi Mesgar; Fathollah Moztarzadeh
Volume 3, Issue 2 , June 2009, , Pages 135-149
Abstract
In this paper, dissolution kinetics of Amorphous Calcium Phosphate as well as cements in the Simulated Osteoclastic Medium (SOM) was evaluated based on the Shrinking Core models considering the liquid-solid reactions. Based on this model, three steps may be considered as controlling steps in the system: ...
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In this paper, dissolution kinetics of Amorphous Calcium Phosphate as well as cements in the Simulated Osteoclastic Medium (SOM) was evaluated based on the Shrinking Core models considering the liquid-solid reactions. Based on this model, three steps may be considered as controlling steps in the system: diffusion of component A through the surrounding films, reaction of component A with solid on the surface and diffusion through the interface. Two cases were considered here: 1. Shrinking Core model with formation of the intermediate phase 2. Shrinking Core model without formation of the intermediate phase Then, experimental data were used for the evaluation of the controlling steps and its mechanism (s). The results showed that enough amounts of calcium were entered into the solution in the initial stage of the process. This in turn causes to form a film on the particles, and the potential of calcium carbonate complex, resulted in the reduction of calcium saturation in the system. The amounts of entered calcium into the solution were higher in the amorphous system. In other words, a longer time is required in the crystalline system for more entrance of calcium into the solution (as in the sample H1T). Based on these observations, it was concluded that the approximately crystalline cements with carbonate falls between the crystalline cements without carbonate and amorphous system (The amounts of entered calcium into the solution). Dissolution rate of ACCPs in the Simulated Osteoclastic Medium (SOM) was dependent on the contents of carbonate and remaining water. Dissolution behavior in the SOM showed that the behavior of ACCP (high carbonate)–DCPD–PHA–Gelatin system was comparable to the ACCP (low carbonate)-DCPD. The presence of PHA and gelatin in cement system decreased the dissolution rate. The dissolution kinetics of the cements and ACCPs in the SOM was likely controlled by the formation of an acid-resisting ACP and/or DCPD as product layer.
