Bio-Medical Materials and Engineering - Volume 16, issue 1

Authors: Joyce, T.J. | Rieker, C. | Unsworth, A.

Article Type: Research Article

Abstract: Six metacarpophalangeal prostheses were each wear tested to five million cycles. Each prosthesis consisted of a metacarpal component with an approximately hemispherical shell on a titanium body, articulating against a titanium phalangeal component. Four prostheses had a shell made from ultra-high molecular weight polyethylene (UHMWPE) and two had a shell made from polyether ether ketone (PEEK). The tests were undertaken using a finger wear simulator. Despite pre-soaking and the use of control components, lubricant uptake by the metacarpal components was significant. Gravimetrically, the UHMWPE test components showed a greater weight gain than the UHMWPE control components. Therefore there was no …apparent wear of any of the UHMWPE test metacarpal components. The original concentric machining marks of the UHMWPE components could still be seen after five million cycles of testing. For the metacarpal components with PEEK shells, gravimetric wear could be measured. Gravimetrically, all of the titanium phalangeal components showed little or no wear. Light scratches in the direction of sliding appeared on the articulating faces of all metacarpal and phalangeal test components, indicating slight abrasive wear. Show more

Keywords: Metacarpophalangeal, wear, UHMWPE, soaking, titanium, finger simulator

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 1-10, 2006

Authors: Tadano, Shigeru | Okoshi, Taro

Article Type: Research Article

Abstract: This paper presents an X-ray diffraction method of measuring the residual stress/strain in bone tissue of rabbit's tibia. To derive the residual stress, bone powder of the diameter less than 40 micrometers was used as a control specimen at non-stressed state. From the X-ray measurements, it was clear that the distribution of residual stress existed in the bone tissue. The tensile residual stress at bone axial direction occurred in the proximal-medial region of rabbit's tibia. The compressive stress occurred in the other regions. In addition, the mechanism to generate the residual stress was investigated by sequential cutting of the tibiofibula …system from bone structure scale to bone tissue scale. The remodeling is a phenomenon that the bone structure adapts functionally to mechanical environment. The residual stress will become a mechanical trigger to induce the remodeling. Show more

Keywords: Biomechanics, residual stress, X-ray diffraction, bone structure, bone tissue, rabbit's tibia, bone remodeling

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 11-21, 2006

Authors: Okumura, Noriko | Yoshikawa, Takafumi | Iida, Jin | Nonomura, Akitaka | Takakura, Yoshinori

Article Type: Research Article

Abstract: The effect of genistein, a soybean isoflavone, on new bone formation by bone marrow cells from mature rats and humans was examined. Bone marrow cells were collected from the femoral diaphysis of 7-week-old Fisher rats, cultured in MEM containing fetal calf serum and then cultured with or without the addition of dexamethasone to the bone-forming medium. Genistein was added at concentrations of 10−5 ,10−6 ,10−7 or 10−8 M. Bone formation was examined 2 weeks after culture. After informed consent was obtained from a 55-year-old woman with lumbar spondylosis deformans, bone marrow cells were collected from her ilium for …culture by the same process, and bone formation investigated. In both rats and humans, when dexamethasone was added to the bone-forming medium, genistein (10−7 M and 10−8 M) caused a significant increase in the levels of calcium, alkaline phosphatase, and DNA compared with cells not cultured in genistein. In conclusion, genistein was found to promote bone formation at lower concentrations across species, and thus may be useful as a bone formation-promoting factor. Show more

Keywords: Genistein, dexamethasone, marrow cell, osteogenesis, tissue engineering

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 23-32, 2006

Authors: Ozeki, K. | Fukui, Y. | Aoki, H.

Article Type: Research Article

Abstract: Germanium apatite was synthesized via the solid-state reaction between GeO2 and (NH4 )3 PO4 . The synthesized materials were characterized using XRD, and thermal analysis was carried out using TG-DTA. Ge2 P2 O7 was preferentially produced at temperatures between 300–900°C, and at temperatures above 1000°C, germanium apatite (Ge5 O(PO4 )6 , GeAp) was synthesized. In solubility tests, 0.36% and 0.65% of Ge ions were liberated from GeAp powder in distilled water at 37 and 80°C after four weeks, respectively. A GeAp aqueous solution maintained at 37°C was strongly acidic with a pH=1.67 after four weeks. The growth rate …of human adult gingival fibroblast cells in a medium that included GeAp, HA, and GeO2 was investigated. The growth rate of the cells in a 0.1 mg/ml GeAp medium was almost the same as that in the control. The cell growth was restricted in a 1.0 mg/ml GeAp medium, whereas the cell growth in a pH-adjusted 1.0 mg/ml GeAp medium at pH=7.60 was higher than that in non-adjusted medium at pH = 7.06. Show more

Keywords: Germanium apatite, cytotoxicity, cell culture, hydroxyapatite

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 33-41, 2006

Authors: Van de Putte, M. | Hagemeister, N. | St-Onge, N. | Parent, G. | de Guise, J.A.

Article Type: Research Article

Abstract: The use of a treadmill to evaluate gait patterns makes it possible to analyze many gait cycles and stride to stride variations. The objective of this study was to assess the time required for a subject to habituate to walking on a treadmill. The evolution of knee kinematics and spatio-temporal parameters were analyzed to measure habituation to walking on the treadmill. To obtain this information, data were recorded on 10 healthy subjects for about 45 minutes as they walked on a treadmill. A steady state was attained for knee kinematics and most spatio-temporal parameters at the time the treadmill had …attained its maximal speed (approximately 30 seconds). However, 10 minutes were necessary for stride length to become reproducible. Time for habituation to walking on a treadmill must be considered when kinematics are evaluated during gait of healthy and disabled subjects. We have shown that, at least for young, healthy individuals who are non-naïve to walking on a treadmill, a 10-minute warm-up is enough before three-dimensional knee kinematics and spatio-temporal data can be recorded. Show more

Keywords: Gait, three-dimensional kinematics, spatio-temporal parameters, habituation, treadmill

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 43-52, 2006

Authors: Wu, John Z. | Cutlip, Robert G. | Welcome, Daniel | Dong, Ren G.

Article Type: Research Article

Abstract: Knowledge of viscoelastic properties of soft tissues is essential for the finite element modelling of the stress/strain distributions in finger-pad during vibratory loading, which is important in exploring the mechanism of hand-arm vibration syndrome. In conventional procedures, skin and subcutaneous tissue have to be separated for testing the viscoelastic properties. In this study, a novel method has been proposed to simultaneously determine the viscoelastic properties of skin and subcutaneous tissue in uniaxial stress relaxation tests. A mathematical approach has been derived to obtain the creep and relaxation characteristics of skin and subcutaneous tissue using uniaxial stress relaxation data of skin/subcutaneous …composite specimens. The micro-structures of collagen fiber networks in the soft tissue, which underline the tissue mechanical characteristics, will be intact in the proposed method. Therefore, the viscoelastic properties of soft tissues obtained using the proposed method would be more physiologically relevant than those obtained using the conventional method. The proposed approach has been utilized to measure the viscoelastic properties of soft tissues of pig. The relaxation curves of pig skin and subcutaneous tissue obtained in the current study agree well with those in literature. Using the proposed approach, reliable material properties of soft tissues can be obtained in a cost- and time-efficient manner, which simultaneously improves the physiological relevance. Show more

Keywords: Soft tissue, skin, subcutaneous, viscoelastic, creep, relaxation

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 53-66, 2006

Authors: Chen, Yi-Chen | Hu, Kuang-Hu | Li, Fang-Zhen | Su, Wan-Fang | Zhang, Bao-Lin

Article Type: Research Article

Abstract: This paper introduces a three-dimensional (3D) reconstruction algorithm of the brain stem nuclei based on fast centroid auto-registration. The research is based on methods and theories of computer stereo vision, and by image information processing three-point pattern local search, registration and auto-tracing for the centroids of the brain stem nuclei were accomplished. We adopt two-peak threshold, edge detection and grayscale image enhancement to extract contours of the nuclei's structures. The experimental results obtain the spatial structure information and 3D image of the brain stem nuclei, show spatial relationship between 14 pairs of nuclei, and quantitate morphological parameters of each type …of nuclei's 3D structure. This work is significant to neuroanatomy research and clinic applications. Furthermore, a software system named BRAIN.HUK is established. Show more

Keywords: Brain stem nuclei, centroid registration, 3D reconstruction, 3D structure quantification

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 67-75, 2006

Authors: Gu, Haihua | Zhang, Song | Qiao, Ye | Luo, Zhichang | Zeng, Yanjun | Wang, Qi

Article Type: Research Article

Abstract: Objective: To investigate the maternal hemodynamic changes that occurs during pregnancy. To find out the difference that lie in healthy pregnancy and women with gestational hypertension. To introduce a method that is applied to shift high-risk women of gestational hypertension in pregnancy women. Method: Serial hemodynamic investigations (total 8 times) were performed throughout pregnancy period by radioulnar pulse wave electrical monitoring in 182 women (130 with healthy pregnancies, 52 with gestational hypertension). Analysis of variance with repeated measurements was used to evaluate the course of a number of hemodynamic indices. To identify the correlation between these changes and gestational hypertension …by using above method. Results: A significant difference in mean arterial pressure (MAP), cardiac output (CO), cardiac index (CI), total Peripheral Resistance (TPR) and heart rat (HR) was observed different between normal pregnancy and women with gestational hypertension. The changes of parameters in normal woman and gestational hypertension were recorded and the mechanism of gestational hypertension was heterogenous. Conclusion: These results provide sensitive parameters for use in early risk assessment and as a guide to preventive intervention during pregnancy. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 1, pp. 77-82, 2006