Bio-Medical Materials and Engineering - Volume 23, issue 6

Authors: Sugita, Shukei | Matsumoto, Takeo

Article Type: Research Article

Abstract: There is growing evidence of heterogeneous distribution of collagen fibers in the aortic wall. To investigate the effects of collagen microstructure on local aortic wall deformation, porcine thoracic aortas were sliced into 100 μm-thick sections perpendicular to their radial direction and stretched biaxially with a laboratory-made tensile tester under a microscope equipped with a birefringence imaging system. Strain tensor components were calculated from fluorescent images of the cell nuclei for each 50×50 μm2 area. Retardance Ret and slow axis azimuth θ were measured as indices of collagen density and fiber direction, respectively. Aortic wall deformation was highly heterogeneous: standard …deviations of strains were significantly larger, by 3–5 times, in aortic slices than in homogeneous silicone sheets. A significant negative correlation was found between maximum principal strain and Ret (R=−0.077), and a positive correlation between minimum principal strain direction and θ (R=0.345). These indicate that the aorta is less distensible in areas with higher collagen density and in the direction of collagen fiber alignment. Microscopic heterogeneity may induce heterogeneous responses of smooth muscle cells and have crucial effects on mechanical homeostasis in the aortic wall. Show more

Keywords: Artery structure, biaxial stretch test, birefringence, connective tissue, mechanical properties

DOI: 10.3233/BME-130771

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 447-461, 2013

Authors: Oya, Koki | Sakamoto, Naoya | Sato, Masaaki

Article Type: Research Article

Abstract: BACKGROUND: Cells in the arterial wall are normally subjected to approximately 10% cyclic stretch due to pulsatile blood flow. In addition, cells in the walls of abdominal aortic aneurysms (AAA) experience hypoxic conditions caused by the accumulation of intraluminal thrombus. Such combined stimulation by hypoxia and stretch can induce abnormal functions in macrophages that infiltrate into the AAA walls; however, the details of these effects are unknown. OBJECTIVE: The aim of this study is to know the influence of a combination of cyclic stretch and hypoxia on the macrophage morphology. METHODS: Morphological changes, such as aspect ratio and …orientation, in macrophages exposed to 10% cyclic stretch and 2.2% O2 hypoxia during 24 h were evaluated with usage of ImageJ software. We also assessed expression of hypoxia-inducible factor-α (HIF-1α), an intracellular signaling factor, in macrophages by western blotting. RESULTS: The results indicate that hypoxia significantly suppresses stretch-induced orientation in the direction of the stretch and elongation of macrophages. We also found that the combination of cyclic stretch and hypoxia significantly increased HIF-1α expression. CONCLUSIONS: These results suggest that hypoxia suppresses morphological responses of macrophages to cyclic stretch by elevating HIF-1α expression. Show more

Keywords: Abdominal aortic aneurysm, macrophages, hypoxia inducible factor-1α, cyclic stretching, hypoxia

DOI: 10.3233/BME-130770

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 463-471, 2013

Authors: Nguyen, Vinh Quang | Ishihara, Masayuki | Mori, Yasutaka | Nakamura, Shingo | Kishimoto, Satoko | Fujita, Masanori | Hattori, Hidemi | Kanatani, Yasuhiro | Ono, Takeshi | Miyahira, Yasushi | Matsui, Takemi

Article Type: Research Article

Abstract: We previously reported a simple method for the preparation of size-controlled spherical silver nanoparticles (Ag NPs) generated by autoclaving a mixture of silver-containing glass powder and glucose. The particle size is regulated by the glucose concentration, with concentrations of 0.25, 1.0 and 4.0 wt% glucose providing small (3.48±1.83 nm in diameter), medium (6.53±1.78 nm) and large (12.9±2.5 nm) particles, respectively. In this study, Ag NP/chitosan composites were synthesized by mixing each of these three Ag NP suspensions with a 75% deacetylated (DAc) chitosan suspension (pH 5.0) at room temperature. The Ag NPs were homogeneously dispersed and stably embedded in the …chitosan matrices. The Ag NP/chitosan composites were obtained as yellow or brown flocs. It was estimated that approximately 60, 120 and 360 μg of the small, medium and large Ag NPs, respectively, were maximally embedded in 1 mg of chitosan. The bactericidal and anti-fungal activities of the Ag NP/chitosan composites increased as the amount of Ag NPs in the chitosan matrix increased. Furthermore, smaller Ag NPs (per weight) in the chitosan composites provided higher bactericidal and anti-fungal activities. Show more

Keywords: Silver-nanoparticles, chitosan, composites, bactericidal, anti-fungal

DOI: 10.3233/BME-130772

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 473-483, 2013

Authors: Kohata, Kazuhiro | Itoh, Soichiro | Takeda, Shu | Kanai, Misa | Yoshioka, Taro | Suzuki, Hiroyuki | Yamashita, Kimihiro

Article Type: Research Article

Abstract: Effectiveness of an alternating electric current (AC) stimulation in prevention of bone deformity for comminuted intraarticular fracture of distal radius were verified by comparing postoperative results treated with a wrist-bridging external fixator combined with or without an AC stimulator (EF and NEF, respectively), and a palmar locking plate (LP). This study evaluated 92 cases (mean age 67.9±11.4 years) of type C2 and 60 cases (mean age 69.7±9.5 years) of type C3 distal radius fractures, as classified by the Association for Osteosynthesis. In total, 55 and 24 cases were treated with EF and NEF, respectively; and 73 cases were treated with …LP. Callus appeared 27.5±4.6 days postoperatively and the external skeletal fixation period was significantly shorter in the EF group than in the NEF group. The decrease in radial length was significantly lower in the EF group when compared to the LP group. There were no significant differences among the groups for the other radiographic and functional parameters. AC stimulation combined to the external fixation may be a promising method to prevent postoperative deformity in the severely comminuted intraarticular fractures by accelerating callus maturation and facilitating new bone bridging across the gap of fracture site. Show more

Keywords: Alternating electric current (AC) stimulation, comminuted intraarticular fracture, distal radius fracture, wrist-bridging external fixator, palmar locking plate

DOI: 10.3233/BME-130774

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 485-493, 2013

Authors: Lin, Hung-Ming | Pan, Yung-Ning | Liu, Chien-Lin | Huang, Li-Ying | Huang, Chang-Hung | Chen, Chen-Sheng

Article Type: Research Article

Abstract: Dynamic spinal fixators, such as the Dynesys (DY) and K-ROD (KD) systems, are designed to restore spinal stability and to provide flexibility. The long-term complications of implant breakage and the biomechanics of the adjacent and the bridged levels using the KD system are still unknown. Therefore, this study aims to investigate and compare the biomechanical effects of the KD system and the DY system. Finite element (FE) models of the degenerated lumbar spine, the DY system, and the KD system were each reconstructed. Hybrid-controlled analysis was applied in the three FE models. The FE results indicated that the KD system …supplies the most stiffness during extension and the least stiffness during flexion, in contrast to the DY system. In contrast to the DY system, the KD system increased the facet contact force of the adjacent level, but this system decreased the screw stress on the cranial adjacent disc and the pedicle during flexion. Show more

Keywords: Finite element analysis, biomechanics, dynamic spinal stabilization devices, K-ROD system, Dynesys

DOI: 10.3233/BME-130766

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 495-505, 2013

Authors: Vyalikh, Anastasia | Mai, Ronald | Scheler, Ulrich

Article Type: Research Article

Abstract: High-resolution solid-state NMR based on combined rotation and multipulse spectroscopy (CRAMPS) has been applied to study chemical structures of dental tissues. The samples of human enamel, crown dentine and root dentin studied in this work were used without chemical pre-treatment. The quantitative 1 H NMR spectra permit an assignment to different structures and a quantification of the content of hydroxyl groups. While there is 40% hydroxyl content in the enamel, there is significantly less in the dentin, 14% in the crown and 9% in the root. Thus this study provides the direct evidence of OH− ion deficiency in all …dental tissues supporting earlier findings that bone and dental mineral apatite is poorly hydroxylated. Show more

Keywords: Dentine, enamel, mineral, hydroxyapatite, hydroxyl groups, solid-state NMR spectroscopy, 1H CRAMPS

DOI: 10.3233/BME-130769

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 507-512, 2013

Authors: Hossen, A. | Muthuraman, M. | Al-Hakim, Z. | Raethjen, J. | Deuschl, G. | Heute, U.

Article Type: Research Article

Abstract: A new technique for discrimination of Parkinson tremor from essential tremor is presented in this paper. This technique is based on Statistical Signal Characterization (SSC) of the spectrum of the accelerometer signal. The data has been recorded for diagnostic purposes in the Department of Neurology of the University of Kiel, Germany. Two sets of data are used. The training set, which consists of 21 essential-tremor (ET) subjects and 19 Parkinson-disease (PD) subjects, is used to obtain the threshold value of the classification factor differentiating between the two subjects. The test data set, which consists of 20 ET and 20 PD …subjects, is used to test the technique and evaluate its performance. Three of twelve newly derived SSC parameters show good discrimination results. Specific results of those three parameters on training data and test data are shown in detail. A linear combination of the effects of those parameters on the discrimination results is also included. A total discrimination accuracy of 90% is obtained. Show more

Keywords: Statistical signal characterization, FFT spectrum, Parkinson tremor, essential tremor, accelerometer signals, discrimination

DOI: 10.3233/BME-130773

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 513-531, 2013

Authors: Lee, Ming-Yih | Tsai, Wen-Wei | Chen, His-Jung | Chen, Jyh-Ping | Chen, Chih-Hao | Yeh, Wen-Lin | An, Jia

Article Type: Research Article

Abstract: The aim of this study is to evaluate a soft/hard bi-phase scaffold for cartilage tissue engineering. Chondrocyte proliferation, glycoaminoglycan production and total collagen content are compared between laser-sintered porous polycaprolactone (PCL) scaffolds with and without a thermoresponsive hydrogel grafted with hyaluronic acid and gelatin. The in vitro results show that scaffolds loaded with hydrogel have a higher initial chondrocyte attachment than PCL scaffolds. At day 21 and 28, scaffolds loaded with hydrogel have a significantly higher glycosaminoglycan (GAG) production than PCL scaffolds alone, and total collagen content including collagen type II in the hydrogel-loaded group is three times higher than …the group without hydrogel. It is concluded that the laser-sintered porous PCL scaffold has good cytocompatibility, and that the hydrogel phase is able to enhance initial chondrocytes attachment as well as GAG and collagen production of chondrocytes. This study suggests that a soft/hard bi-phase scaffold may be used for cartilage tissue engineering to enhance in vitro chondrogenesis. Show more

Keywords: Rapid prototyping, selective laser sintering, thermoresponsive hydrogel, cartilage tissue engineering, chondrocyte, hyaluronic acid, gelatin

DOI: 10.3233/BME-130767

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 533-543, 2013

Authors: Zhao, Yahong | Zhao, Weijia | Yu, Shu | Guo, Yibing | Gu, Xiaosong | Yang, Yumin

Article Type: Research Article

Abstract: In this study, electrospinning was performed to fabricate silk fibroin (SF) nanofibrous mats, which were used as substrates for in vitro culture of rat hippocampal neurons. The light and electron micrographs demonstrated that the electrospun SF nanofibrous mat supported the survival and growth of the attached hippocampal neurons. MTT assay and immunocytochemistry in couple with Western blot analysis respectively indicated there was no significant difference in both the cell viability and expression levels of some proteins, including GAP-43, MAP-2, NF, and β-tubulin, between hippocampal neurons cultured in the electrospun SF nanofibrous mat extract and in plain neuronal medium. Our results …indicated that electrospun SF nanofibrous mats were biocompatible to primary culture of hippocampal neurons without cytotoxic effects on the cell phenotype and functions, raising a potential possibility of using these mats for CNS therapeutic applications. Show more

Keywords: Biomaterials, nanofiber, biocompatibility, silk fibroin, hippocampal neurons

DOI: 10.3233/BME-130775

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 545-554, 2013

Authors: Agudelo, Carlos A. | Yamaoka, Tetsuji

Article Type: Research Article

Abstract: Magnetic resonance imaging (MRI) has been recognized as a non-invasive technique for visualizing the ultrastructure of a tissue at high resolution. The work reported here showed the utility of MRI for visualizing the fate of EPCs, and demonstrate how it can be used to further our understanding of angiogenesis mechanisms. The recently developed contrast agent dextran mono-N-succinimidyl 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate-gadolinium3+ (Dex-DOTA-Gd3+ ) was used to label endothelial progenitor cells (EPCs). The faith of the transplanted labeled cells in the rat models of ischemic hind limbs was studied by images obtained by MRI. The pattern of migration of Dex-DOTA-Gd3+ -labeled …EPCs could be observed and tracked by MRI for a long time and analyzed the change in the migration of the labeled cells. The ability of Dex-DOTA-Gd3+ to provide a clear pattern of cell migration to the limb was confirmed and most importantly, a different behavioral pattern was identified in the migration of labeled cells when an anomaly appeared in the MRI acquisition images 5 days post transplantation. Show more

Keywords: Magnetic resonance imaging, dextran, progenitor cells, granuloma

DOI: 10.3233/BME-130768

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 555-566, 2013

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 567-573, 2013

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 23, no. 6, pp. 575-577, 2013