Structure and Mechanical Properties of As-Cast Ti-5Sn-xMo Alloys.

Ti-5Sn-xMo (x = 0, 1, 3, 5, 7.5, 10, 12.5, 15, 17.5, and 20 wt %) alloys were designed and prepared for application as implant materials with superior mechanical properties. The results demonstrated that the crystal structure and mechanical properties of Ti-5Sn-xMo alloys are highly affected by their Mo content. The as-cast microstructures of Ti-5Sn-xMo alloys transformed in the sequence of phases α' → α″ → ß, and the morphologies of the alloys changed from a lath structure to an equiaxed structure as the Mo content increased. The α″-phase Ti-5Sn-7.5Mo (80 GPa) and ß-phase Ti-5Sn-10Mo (85 GPa) exhibited relatively low elastic moduli and had excellent elastic recovery angles of 27.4° and 37.8°, respectively. Furthermore, they exhibited high ductility and moderate strength, as evaluated using the three-point bending test. Search for a more suitable implant material by this study, Ti-5Sn-xMo alloys with 7.5 and 10 wt % Mo appear to be promising candidates because they demonstrate the optimal combined properties of microhardness, ductility, elastic modulus, and elastic recovery capability.

Coelectrospinning of chitosan/alginate fibers by dual-jet system for modulating material surfaces.

Chitosan and alginate are two frequently used biomaterials for tissue engineering. In this study, electrospinning technique was applied for their nanofiber fabrications to mimic extracellular environment (ECM). Polyethylene oxide (PEO) was applied to increase viscosities of polymer solutions to obtain nanofibers with appropriate morphologies. To modulate surface properties, a dual jet system was developed to coelectrospin chitosan and alginate nanofibers on one substrate. Because the deposition rates of electrospun fibers linearly correlated to the perfusion rates of polymer solutions, the composition ratios of nanofibers were thus manipulated, which determined both the chemical properties and hydrophobicity of fibrous mats. In vitro cell culture results suggested that the cell morphology highly depended on the fiber composition, and the composite nanofibers demonstrated higher biocompatibility than that on pure fibers. Finally, the degradation of alginate fibers was controlled by the crosslinking process. Reducing calcium ions resulted in partial fiber degradation, by which the composition ratios of nanofibers varied with time. This dynamically changed environment performed a promising property to improve viability of surface cells. Through this tunable system, surface properties of scaffolds can be finely adjusted to benefit tissue engineering applications.

Opposite associations of osteoprotegerin and ZBTB40 polymorphisms with bone mineral density of the hip in postmenopausal Taiwanese women.

BACKGROUND: An elevated annual incidence rate of hip fracture has been reported among elderly Taiwanese. Moreover, bone mineral density (BMD) is the single most reliable predictor of fragility fractures. We aimed to identify the association between gene sequence variants and hip BMD in postmenopausal Taiwanese women. METHODS: We prospectively analyzed data from 163 postmenopausal Taiwanese women to test an association between rs7524102, rs6696981, or rs6993813 single-nucleotide polymorphisms (SNPs) and hip BMD. RESULTS: Our study showed that rs6993813 (osteoprotegerin gene) and rs6696981 (ZBTB40 gene) SNPs have an opposite association with hip BMD. For rs6993813 genotypic frequencies, the adjusted odds ratio for hip osteoporosis was 9.53 for individuals with T/T minor allele homozygotes, compared with that of participants with C/C wild-type homozygotes. Hip BMD also had an association with rs6993813 SNPs, especially in T/T minor allele homozygotes. For rs6696981 SNPs, hip BMD in G/T heterozygotes and at least one mutated T allele was higher than that in wild-type G/G homozygotes. CONCLUSION: The gene sequence variant rs6993813 reduced hip BMD and increased the risk of hip osteoporosis, whereas rs6696981 increased hip BMD in postmenopausal Taiwanese women. This indicated that the two SNPs may provide some explanation for the high risk of hip fracture in this population.

Association of interleukin-1 beta (-511C/T) polymorphisms with osteoporosis in postmenopausal women.

BACKGROUND AND OBJECTIVES: Osteoporosis is a common disease of the elderly, in which genetic and clinical factors contribute to the disease phenotype. Since the production of interleukin-1 (IL-1) has been implicated in the bone mass and skeletal disorders, we investigated whether IL-1 system gene polymorphisms are associated with the pathogenesis of osteoporosis in postmenopausal Taiwanese women. METHODS: Osteoporosis is diagnosed by dual-energy x-ray absorptiometry, which measures bone mineral density (BMD) at multiple skeletal sites. We studied the IL-1α (-889C/T), IL-1ß (-511C/T) and the 86 base pair variable number tandem repeat (VNTR) in intron 2 of the IL-1 receptor antagonist (IL-1ra) gene in 117 postmenopausal women with osteoporosis and 135 control subjects without a history of symptomatic osteoporosis. These gene polymorphisms were analyzed by polymerase chain reaction and restriction fragment length polymerase. Blood sugar and other risk factors were also determined. RESULTS: The frequencies of IL-1ß (-511C/T) genotypes (P=.022, odds ratio=1.972) and alleles (P=.02, odds ratio=2.909) showed a statistically significant difference between the two groups. However, we did not find any statistically significant difference in IL-1ß and IL-1ra polymorphisms (P>.05). We also observed a positive relationship between osteoporosis and cholesterol and a weak inverse relationship between blood sugar and osteoporosis in postmenopausal women. CONCLUSIONS: These experimental results suggest that the pathogenesis of osteoporosis is associated with IL-1ß (-511C/T) polymorphism in postmenopausal women. This polymorphism is an independent risk factor for osteoporosis.