Bio-Medical Materials and Engineering - Volume 21, issue 1

Authors: Chen, Hao | Sago, Alan | West, Shari | Farina, Jeff | Eckert, John | Broadley, Mark

Article Type: Research Article

Abstract: We present a comparative analysis between biocompatibility test results of wrought and Metal Injection Molded (MIM) ASTM F562-02 UNS R30035 (MP35N) and F1537 UNS R31538 (CCM) alloy samples that have undergone the same generic orthopedic implant's mechanical, chemical surface pre-treatment, and a designed pre-testing sample preparation method. Because the biocompatibility properties resulting from this new MIM cobalt alloy process are not well understood, we conducted tests to evaluate cytotoxicity (in vitro), hemolysis (in vitro), toxicity effects (in vivo), tissue irritation level (in vivo), and pyrogenicity count (in vitro) on such samples. We show that our developed MIM MP35N and CCM …materials and treatment processes are biocompatible, and that both the MIM and wrought samples, although somewhat different in microstructure and surface, do not show significant differences in biocompatibility. Show more

Keywords: MIM, F562, MP35N, F1537, cobalt alloy, biocompatibility, CMM+, microstructure

DOI: 10.3233/BME-2011-0652

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 1, pp. 1-7, 2011

Authors: Tang, C.Y. | Ng, G.Y.F. | Wang, Z.W. | Tsui, C.P. | Zhang, G.

Article Type: Research Article

Abstract: Numerous constitutive models describing the mechanical properties of tendons have been proposed during the past few decades. However, few were widely used owing to the lack of implementation in the general finite element (FE) software, and very few systematic studies have been done on selecting the most appropriate parameters for these constitutive laws. In this work, the visco-hyperelastic constitutive model of the tendon implemented through the use of three-parameter Mooney–Rivlin form and sixty-four-parameter Prony series were firstly analyzed using ANSYS FE software. Afterwards, an integrated optimization scheme was developed by coupling two optimization toolboxes (OPTs) of ANSYS and MATLAB for …estimating these unknown constitutive parameters of the tendon. Finally, a group of Sprague–Dawley rat tendons was used to execute experimental and numerical simulation investigation. The simulated results showed good agreement with the experimental data. An important finding revealed that too many Maxwell elements was not necessary for assuring accuracy of the model, which is often neglected in most open literatures. Thus, all these proved that the constitutive parameter optimization scheme was reliable and highly efficient. Furthermore, the approach can be extended to study other tendons or ligaments, as well as any visco-hyperelastic solid materials. Show more

Keywords: Tendon, visco-hyperelasticity, parameter optimization, FEM

DOI: 10.3233/BME-2011-0653

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 1, pp. 9-24, 2011

Authors: Lee, Hyunah | Jeong, Chanmin | Ghafoor, Kashif | Cho, Sungyeon | Park, Jiyong

Article Type: Research Article

Abstract: Phytic acid (PA) was used as a cross-linking agent for encapsulation of insulin in a chitosan matrix for oral delivery of insulin. PA–chitosan capsules were compared with tripolyphosphate (TPP)–chitosan capsules for stable oral delivery of insulin. During 2 h incubation in simulated gastric fluid, PA–chitosan capsules prepared using pH 6, 6% PA solutions showed better stability than TPP–chitosan capsules prepared using pH 7, 6% TTP solution. PA–chitosan capsules released less than 60% of their encapsulated insulin after 24 h incubation in simulated gastrointestinal fluids. TPP–chitosan capsules showed burst release and virtually the entire insulin content was released in 12 h. …Both capsule types were tested in vivo via oral drug administration using diabetic mice. PA–chitosan capsules significantly decreased blood glucose levels while TPP–chitosan capsules caused a lesser reduction. The relative pharmacological bioactivity of PA–chitosan capsules prepared was 6.4% while that of TPP–chitosan capsules was 1.1%. PA–chitosan capsules appeared to have good potential for use in oral delivery of insulin for sustained control of the blood glucose level. Show more

Keywords: Oral delivery, insulin, phytic acid, chitosan capsule, diabetic mice, bioavailability

DOI: 10.3233/BME-2011-0654

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 1, pp. 25-36, 2011

Authors: Shaeiri, Zahra | Ghaderi, Reza

Article Type: Research Article

Abstract: Gene expression data have extremely high dimensionality with respect to traditional classifiers which causes not to be used efficiently. In this paper a Fuzzy–Rough Gene Selection and Complementary Hierarchical Fuzzy classifier (FRGS–CHF) to classify the gene expression data as a new methodology is proposed. First, some relevant genes are selected using fuzzy–rough attribute selection method. After removing redundant genes, a new complementary hierarchical fuzzy classifier is proposed. The complementary learning mechanism refers to positive and negative learning which are found in the human brain hippocampus. FRGS–CHF is made-up of two parallel hierarchical fuzzy systems; the first is trained with positive …samples whilst the other is treated with negative samples. In contrast to many other methods such as statistical or neural networks, FRGS–CHF provides greater interpretability. It does not rely on the assumption of underlying data distribution. Using complementary and hierarchical approaches, the proposed method exploits the lateral inhibition between output classes and considers the problem as a multidimensional problem. Benchmarked datasets are used to demonstrate the validity and advantages of the proposed method over the other existing methods in terms of the accuracy, better transparency, time efficiency together with fewer fuzzy rules and parameters. Show more

Keywords: Gene expression data analysis, fuzzy–rough feature selection, complementary hierarchical fuzzy classification

DOI: 10.3233/BME-2011-0655

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 1, pp. 37-52, 2011

Authors: Kawakami, Masahiro | Tomita, Naohide | Shimada, Yasuhiro | Yamamoto, Koji | Tamada, Yasushi | Kachi, Naoyoshi | Suguro, Toru

Article Type: Research Article

Abstract: Chondrocytes distribution and cartilage formation in three types of fibroin sponges with different average pore sizes (40–80, 80–120 and 100–140 μm) was measured. The image processing was performed combining two methods to identify cells automatically: extraction of local maximum luminance and multi-threshold analysis. The results showed that initial accumulation of chondrocytes localized at surface area at 3 h in the small and medium-pore groups, however, the difference in the cell distributions become equivalent until 24 h after seeding. Cartilaginous tissue was well formed in each group at 21 days, and that in the smaller pore group tend to distribute at …the surface area. Spherical tissues were located at the subsurface (200–600 μm below the surface) of the sponge in the medium- and large-pore groups at 21 days. Local cell aggregation was observed at 24 h at the same depth of the fibroin sponge as the spherical tissues observed at 21 days. These results suggest that the initial cell condensation process till 24 h after seeding play an important role in cartilage tissue formation. Show more

Keywords: Fibroin sponge, chondrocyte, initial cell distribution, multi-threshold analysis

DOI: 10.3233/BME-2011-0656

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 1, pp. 53-61, 2011