Bio-Medical Materials and Engineering - Volume 17, issue 4

Authors: Forest, P. | Morfin, F. | Bergeron, E. | Dore, J. | Bensa, S. | Wittmann, C. | Picot, S. | Renaud, F.N.R. | Freney, J. | Gagnieu, C.

Article Type: Research Article

Abstract: In the last few years, regulations for biomolecule production, and especially for extraction and purification of animal molecules such as collagen, have been reinforced to ensure the sanitary safety of the materials. To be authorized to market biomaterials based on collagen, manufacturers now have to prove that at least one step of their process is described in guidelines to inactivate prion, viruses, and bacteria. The present study focuses on the inactivation step performed during the extraction and purification of porcine type I atelocollagen. We chose to determine the reduction factor of a 1 M NaOH step on porcine parvovirus and …four bacterial strains inactivation. During the extraction step, we deliberately inoculated the collagen suspension with the different microorganisms tested. Then, 1 M NaOH was added to the suspension for 1 hour at 20°C. We demonstrated that this treatment totally inactivated S. aureus, P. aeruginosa, C. albicans and A. niger which are bacterial strains responsible of severe human pathology. The reduction factors reached more than 4 logs for B. cereus spores and 4 logs for the porcine parvovirus. are encouraging as those two microorganisms are known to be very resistant to inactivation. Show more

Keywords: Collagen, sodium hydroxide, porcine parvovirus, bacteria, inactivation

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 199-208, 2007

Authors: Sethumadhavan, Rao | Taguchi, Tetsushi | Tanaka, Junzo | Tateishi, Tetsuya

Article Type: Research Article

Abstract: We developed a novel tissue adhesive consisting of human serum albumin (HSA) and tartaric acid derivative (TAD). Four different concentrations of TAD namely, 0.05 mM, 0.1 mM, 0.2 mM and 0.3 mM were mixed with 40%, 42% and 44% HSA individually and were made in the form of disks. J774A.1 mouse macrophage cells were seeded on top of these disks. The disks were pre-treated with sterile water and Eagle's medium before every seeding. All the seeding was incubated from 1 day to 3 days before making any investigations on it. SEM images were recorded and it was observed that these …cells adhered to these materials very well. Mouse IL-6 cytokine expressions were studied using ELISA. It was seen from the cytokine expression results that the release of IL-6 was minimum at 0.3 mM TAD concentrations with 44% HSA disks. No significant difference was observed in the cytokine expressions of IL-6 at 42% and 44% HSA at all concentrations of TAD studied in this work. mRNA gene expressions of IL-6 were investigated using RT-PCR technique. In 40% HSA, the gene expression level of IL-6 gene did not change during 3-day-culture in the range of TAD concentration of 0.05 mmol to 0.2 mmol. However, 0.3 mM TAD suppressed the gene expression at all concentration of HSA. In 42% HSA, although 0.05 mM and 0.1 mM TAD did not affect the gene expression, 0.2 mM and 0.3 mM TAD induced the expression level with incubation time. In 44% HSA, all the concentration of TAD increased the expression level even though the cytokine expression levels were quite low. Hence it could be thought that the expression at the cytokine level is quite insignificant where as it is to be considered at the gene expression level. On the whole, 0.3 mM TAD with 44% HSA could be considered as a challenging material as a tissue adhesive material for use in the field of tissue engineering. Show more

Keywords: Tissue adhesive, TAD, SEM, IL-6, RT-PCR

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 209-217, 2007

Authors: Geng, Jianhua | Chen, Yingmao | Chen, Shengzu | Si, Hongwei | Tian, Jiahe

Article Type: Research Article

Abstract: The standard uptake value (SUV) is an important semi-quantitative parameter in positron emission tomography (PET). But SUV is not available in dual-head coincidence imaging system (DHC) which is widely used in clinical practice. This study was designed to develop a method for measuring SUV in DHC system, and then compared SUV in DHC and SUV in PET. Method: Firstly, the calibration factor (CF) for converting the voxel count rate to radioactivity concentration was determined by a phantom study in DHC. Then the method for calculating SUV in DHC was formulated. Finally, SUV in DHC and SUV in PET were compared …through another phantom study. The phantoms used in the comparing study were cylindrical and consisted of several hot lesions. Results: The CF varied with the detected single count rate in a biquadratic polynomial; the lesion's radioactivity concentration was got based on the CF and the voxel count rate. From the lesion's radioactivity concentration, the lesion's SUV in DHC was obtained. The comparison study showed that SUV in PET was higher than SUV in DHC. The SUV in both DHC and PET increased with increasing sizes of lesions and were related with the reconstruction algorithm. Conclusions: SUV in DHC images could be obtained in our method; the value in DHC images was lower than that in PET image; and many factors, such as system performance, lesion's size, and reconstruction algorithm could influence the SUV accuracy in both DHC and PET. Show more

Keywords: Dual-head coincidence imaging system (DHC), standard uptake value (SUV), positron emission tomography (PET)

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 219-227, 2007

Authors: Najarian, Siamak | Firouzi, Faramarz | Fatouraee, Nasser | Dargahi, Javad

Article Type: Research Article

Abstract: Left ventricular assist devices (LVADs) are among the most important mechanical artificial hearts in medical equipment industry. Since the need for heart transplantation is on the rise, there is a requirement for implantable LVADs, which can be safely used for long-term purposes. One of the most promising kinds of these devices is the sac-type LVAD (ST-LVAD) that has the ability to generate pulsatile flow. In this study and for the first time, three different models of ST-LVAD are analyzed numerically. In the first model, the motion of the elastic membrane wall is simplified, while in the second model, the motion …is assumed to be wavy. The pressure boundary conditions are added to the second model to allocate for the effect of pressure on the flow pattern, and hence, form the third model. The simulation results of the analyzed models show that in this particular type of LVAD, the viscous term of the applied stress from the fluid on the moving wall is negligible, compared with the pressure term. Additionally, it can be concluded that the motion pattern of the moving wall does not affect the blood flow pattern in a great deal. Furthermore, the inclusion of the fluid pressure in the boundary conditions does not have a major influence on the blood flow pattern. Show more

Keywords: Numerical simulation, left ventricular assist device, sac-type blood pump, moving membrane

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 229-233, 2007

Authors: Najarian, Siamak | Dargahi, Javad | Farmanzad, Farhad

Article Type: Research Article

Abstract: In this work, a finite element formulation for the analysis of the elastodynamic behavior of the human aorta is presented. In this formulation, a one-dimensional approach was adopted and a comprehensive computer program was written and employed in the mathematical analysis. All the necessary material and geometrical parameters were appropriately incorporated in the simulation. A comparison was made between the simplified elasticity theory and the one proposed in this study using the poroelasticity theory. The effects of certain parameters including the fluid density and the material permeability of the matrix on the behavior of the aortic tissue were investigated. According …to these findings, the higher the density of the liquid in the tissue, the more delay will be observed in the resonance frequencies. It was also concluded that in the poroelasticity theory, the resonance frequencies occur at a later stage compared with the elasticity theory. The permeability of liquid into the pores and its damping effect are the two factors that contributed to the delay in the resonance. It was observed that at a frequency of 10 Hz, up to a permeability of about 10−8 m4 /N.s, the effect on the magnitude of the amplitude is negligible. However, from this threshold value up to a point at which the permeability is equal to 10−5 m4 /N.s, there is a corresponding increase in the amplitude. Show more

Keywords: Finite element modeling, poroelasticity, elastodynamic, biphasic medium

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 235-240, 2007

Authors: Wang, Yan | Wei, Hung-Wen | Yu, Tzai-Chiu | Cheng, Cheng-Kung

Article Type: Research Article

Abstract: Few studies have stressed on the sensitivity of stress distribution in different mechanical properties of the articular cartilage and subchondral bone. The purpose of this study was to establish parametric variations of mechanical factors individually and examine how these biomechanical effects influenced the cartilage and subchondral bone plate stress fields in the hip joint. A finite element model including acetabulum and proximal femur was established to study the stress change associated with the thinning of cartilage, the increasing of subchondral bone modulus and the thickening of subchondral bone plate individually. The stress distributions in bone/cartilage interface were evaluated. Sensitivity of …the stress magnitudes to the parametric changes was also analyzed. The results indicated that cartilage thinning has more significant effect than subchondral bone modulus increasing or thickening on the shear stress levels in subchondral bone/cartilage interface. Subchondral bone plate modulus increasing has mild effect on the shear stress in subchondral bone/cartilage interface. Cartilage thinning acts as a major influence on the development of the articular cartilage damage. Show more

Keywords: Osteoarthritis, articular cartilage, subchondral bone, finite element analysis, hip joint

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 241-247, 2007

Authors: Paruchuru, S.P. | Wang, X. | Agrawal, C.M.

Article Type: Short Communication

Abstract: The current methods to measure bone fracture toughness were initially developed for engineering materials and use specimen configurations that demand large samples. However, in many cases it is hard if not impossible to obtain such specimens from limited bone stock. Therefore, a new compact sandwich (CS) test method was formulated to measure the critical strain energy release rate (a measure of fracture toughness) of bone requiring only small samples. This technique may be used to assess bone fracture toughness and subsequently the bone quality.

Keywords: Fracture toughness, stress intensity factor (K), energy release rate (G), elastic compliance, compact sandwich (CS) specimen, finite element analysis (FEA)

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 249-253, 2007

Authors: Shimojo, Nagahiro | Kondo, Chihiro | Yamashita, Kyoko | Hoshino, Takeshi | Hayakawa, Taro

Article Type: Correction

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 4, pp. 255-255, 2007