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  • 1
    Electronic Resource
    Electronic Resource
    Menadione-induced cytotoxicity to rat osteoblasts (1997)
    Springer
    Cellular and molecular life sciences 53 (1997), S. 967-976 
    Details
    ISSN: 1420-9071
    Keywords: Key words. Menadione; oxidative stress; osteoblasts; superoxide dismutase (SOD); catalase.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Oxygen-derived free radical injury has been associated with several cytopathic conditions. Oxygen radicals produced by chondrocytes is an important mechanism by which chondrocytes induce matrix degradation. In the present study, we extend these observations by studying oxidative processes against osteoblasts. Osteoblasts were mixed in in vitro culture with 200 μM menadione. The cytotoxic effect of menadione-induced oxidative stress was monitored by lucigenin- or luminol-amplified chemiluminescence, tetrazolium assay and immunocytochemical study. Results showed that adding menadione induces an oxidative stress on osteoblasts, via superoxide and hydrogen peroxide production, that can be eradicated by superoxide dismutase (SOD) and catalase in a dose-dependent manner. Catalase and the appropriate concentration of dimethyl sulfoxide have a protective effect on cytotoxicity induced by menadione, whereas SOD does not. Menadione-treated osteoblasts have a strong affinity for annexin V, and the nuclei are strongly stained by TUNEL (TdT-mediated dUTP nick-end labelling). The results suggest that menadione-triggered production of reactive oxygen species leads to apoptosis of osteoblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000180050118
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  • 2
    Electronic Resource
    Electronic Resource
    Differential Effects of Bone Mineral Content and Bone Area on Vertebral Strength in a Swine Model (1998)
    Springer
    Calcified tissue international 63 (1998), S. 86-90 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Bone mineral content — Vertebral bone area — Compressive stress — Failure load — Stored strain energy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Since the biomechanical competence of a vertebral body may be closely related to the content and distribution of the bone mineral, we have evaluated the effects of projected vertebral bone area (BA) and bone mineral parameters [bone mineral content (BMC) or bone mineral density (BMD)] on their biomechanical competence. We used dual-energy X-ray absorptiometry (DXA) to assess the bone mineral parameters of 36 swine thoracic vertebrae (T1–T12) and 15 lumbar vertebrae (L1–L5) after removal of the posterior elements. The failure load, compressive stress, and the stored strain energy of these vertebral bodies were assessed by a uniaxial compressive test using an MTS 810 testing system. Multiple regression analysis showed a significantly negative effect of BA and significantly positive effect of BMC on the biomechanical competence (compressive stress, r2= 0.67, P 〈 0.0001; failure load, r2= 0.75, P 〈 0.0001). However, the stored strain energy was only related to the BMC (r2= 0.35, P 〈 0.0001). The contributory effects of BMC and BA on the biomechanical competence were not equal. The effects of BMC was larger than BA in determining the failure load and stored strain energy, whereas the reverse was found for the compressive stress. Using the log-transformed parameters as the regressors resulted in similar results. These results suggested the differential effects of BA and BMC in determining the biomechanical competence of vertebral bodies. We recommend the use of both parameters instead of BMD alone for evaluation of the vertebral biomechanical competence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900494
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  • 3
    Electronic Resource
    Electronic Resource
    Factor of Risk for Hip Fracture in Normal Chinese Men and Women in Taiwan (1999)
    Springer
    Calcified tissue international 65 (1999), S. 422-426 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Factor of risk (Φ) — Hip fracture — Chinese — Bone mineral density — Bone area.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. We have investigated the age-related change in factor of risk (Φ) for the proximal femoral load during free fall in 548 females and 240 males aged 21–79 years. These individuals were divided into either young (age 〈50 years) or old group (age ≥50 years). Another 26 females with hip fractures were included for comparison. The bone mineral density (BMD) of proximal femoral neck was measured by a Norland XR-26 dual-energy X-ray absorptiometer (DXA). The estimated fracture load (L) of femoral neck was calculated from the BMD with the regression equation derived by Courtney et al. [2,3] and estimated fall force (F) by body weight and height according to the regression equation derived by Nakamura et al. [6] respectively. Φ was defined as the quotient of F/L. The results showed an age-related decrease of BMD (P 〈 0.001) in both genders corrected for weight and height. By multiple linear regression analysis, the F decreased significantly with aging corrected for BMD in old males (partial r =−0.255, P 〈 0.01) and increased with aging in all females (young, partial r=0.287, p 〈 0.001; old, partial r = 0.252, P 〈 0.001). L decreased significantly with aging corrected for height and weight in males (young, partial r =−0.401, P 〈 0.01; old, partial r =−0.178, P 〈 0.05) and females (young, partial r =−0.168, P 〈 0.05; old, partial r =−0.459, P 〈 0.001). However Φ decreased with aging in young males (P 〈 0.01) and females (young: P 〈 0.001, old: P 〈 0.001). Φ increased in old women but not in old men, and was higher in old women compared with old men. The 26 patients with hip fractures had a significantly higher Φ value than 85 age-matched women. In conclusion, Φ may provide a comprehensive comparison of the risk of hip fracture in the elderly population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900727
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  • 4
    Electronic Resource
    Electronic Resource
    Biomechanical study of the pitching elbow (1979)
    Springer
    International orthopaedics 3 (1979), S. 217-223 
    Details
    ISSN: 1432-5195
    Keywords: Pitching elbow ; Biomechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les traumatismes par mise en tension des éléments internes du coude du lanceur sont bien connus. Un des facteurs qui contribue à ce syndrome est le valgus extrême produit lors de la phase d'accélération, pendant le lancement de la balle. Les auteurs avancent l'hypothèse que les lancements avec «effet» entraîneraient une contrainte interne encore supérieure, du fait de la pronation et de la supination requises pour faire tourner la balle au cours de son trajet. Le mouvement de lancement est une action complexe de tous les segments du corps pour produire une accélération linéaire et angulaire maximale de la balle. Le but de cette étude est de découvrir les corrélations entre les contraintes subies par le coude et le style de lancement. Nous avons mesuré les accélérations axiale et tangentielle (dans le plan du varus-valgus) au niveau de l'avant-bras à l'aide d'accéléromètres, ainsi que les activités musculaires à l'aide d'un système de télé-électromyographie. La rotation de l'avant-bras est enregistrée à l'aide de photographies stroboscopiques. L'accélération angulaire nécessaire pour produire la rotation de l'avant-bras n'a pas été étudiée. Malgré les différents styles utilisés dans les lancements avec «effet», tous les lanceurs ont un schéma identique d'activité musculaire et d'accélération. Pour les différents styles de lancements, il n'y a pas d'EMG caractéristique, ni de profils d'accélération ou de forces normalisées du coude qui soient discernables. Nous pensons que le facteur principal de cette lésion du coude est vraisemblablement le nombre de lancements et la force avec laquelle la balle est lancée. Les accéléromètres constituent un mode valable d'appréciation du mécanisme du lancement.
    Notes: Summary Medial-tension injuries of the pitching elbow are well recognized. One contributing factor is the extreme valgus which has been noted to occur during the acceleration phase of throwing. It is hypothesized that breaking pitches generate higher medial loading because of the pronation and supination required to impart spin to the ball. The pitching motion is a complex action of all body segments to produce maximum linear and angular acceleration of the ball. The purpose of this study was to correlate elbow loading with pitching style. We measured the forearm segment for axial and tangential (varus-valgus plane) acceleration using accelerometers attached to the forearm and hand. Muscle activity was measured by EMG. Forearm rotation was assessed by stroboscopic photography. Despite different delivery styles when throwing breaking pitches, each pitcher demonstrated patterns of muscle activity and acceleration which were similar. Deceleration forces were lower than acceleration forces. Pronation and supination were documented and contribute to the direction of ball spin. Accelerometers can be used to evaluate pitching mechanics. We suggest that the main factors causing an elbow injury are the amount of throwing and the force with which the ball is thrown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265715
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  • 5
    Electronic Resource
    Electronic Resource
    In vitro and in vivo mechanical evaluations of plasma-sprayed hydroxyapatite coatings on titanium implants: The effect of coating characteristics (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 37 (1997), S. 335-345 
    Details
    ISSN: 0021-9304
    Keywords: bonding-strength ; shear-strength ; simulated body fluid ; push-out measurement ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was undertaken to evaluate the effect of coating characteristics on the mechanical strengths of the plasma-sprayed HA-coated Ti-6Al-4V implant system both in vitro and in vivo. Two types of HA coatings (HACs) with quite different microstructures, concentrations of impurity-phases, and indices-of-crystallinity were used. In vitro testings were done by measuring the bonding-strength at the Ti-6Al-4V-HAC interface, with HACs that had and had not been immersed in a pH-buffered, serum-added simulated body fluid (SBF). The shear-strength at the HAC-bone interface was investigated in a canine transcortical femoral model after 12 and 24 weeks of implantation. The results showed a bonding degradation of approximately 32% or higher of the original strength after 4 weeks of immersion in SBF, and this predominantly depended on the constructed microstructure of the HACs. After the push-out measurements, it was demonstrated that the HACs with higher bonding-strength in vitro would correspondingly result in significantly higher shear-strength at each implant period in vivo. Nevertheless, there were no substantial histological variations between the two types of HACs evaluated. The most important point elucidated in this study was that, among coating characteristics, the microstructure was the key factor in influencing the mechanical stability of the HACs both in vitro and in vivo. As a consequence, a denser HAC was needed to ensure mechanical stability at both interfaces. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 37, 335-345, 1997.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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