Brown, C, Williams, S, Tipper, JL, Fisher, J & Ingham, E 2007, 'Characterisation of wear particles produced by metal on metal and ceramic on metal hip prostheses under standard and microseparation simulation', Journal of Materials Science: Materials in Medicine, vol. 18, no. 5, pp. 819-827.
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Center, JR, Bliuc, D, Nguyen, TV & Eisman, JA 2007, 'Risk of Subsequent Fracture After Low-Trauma Fracture in Men and Women', JAMA, vol. 297, no. 4, pp. 387-387.
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Context There are few published long-term data on absolute risk of subsequent fracture ( refracture) following initial low-trauma fracture in women and fewer in men. Objective To examine long-term risk of subsequent fracture following initial osteoporoti
de Molina, AR, Sarmentero-Estrada, J, Belda-Iniesta, C, Tarón, M, de Molina, VR, Cejas, P, Skrzypski, M, Gallego-Ortega, D, de Castro, J, Casado, E, García-Cabezas, MA, Sánchez, JJ, Nistal, M, Rosell, R, González-Barón, M & Lacal, JC 2007, 'Expression of choline kinase alpha to predict outcome in patients with early-stage non-small-cell lung cancer: a retrospective study', The Lancet Oncology, vol. 8, no. 10, pp. 889-897.
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Frost, SA, Nguyen, ND, Center, JR, Eisman, JA & Nguyen, TV 2007, 'Discordance of longitudinal changes in bone density between densitometers', Bone, vol. 41, no. 4, pp. 690-697.
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Galvin, AL, Tipper, JL, Jennings, LM, Stone, MH, Jin, ZM, Ingham, E & Fisher, J 2007, 'Wear and biological activity of highly crosslinked polyethylene in the hip under low serum protein concentrations', Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, vol. 221, no. 1, pp. 1-10.
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Crosslinked ultra-high molecular weight polyethylene (UHMWPE) has been developed and introduced into clinical practice in order to reduce wear in the hip. Zero wear of highly crosslinked UHMWPE in vitro has been reported by some groups using lubricants with high concentrations of serum proteins in hip simulators. In contrast, some clinical studies have reported finite wear rates. The aim of this study was to compare the wear rates, wear surfaces, and wear debris produced by UHMWPE with different levels of crosslinking in a hip joint simulator, with lower, more physiologically relevant concentrations of protein in the lubricant. The UHMWPEs were tested in the Leeds ProSim hip joint simulator against cobalt-chromium (CoCr) femoral heads. The wear particles were isolated and imaged using a field emission gun scanning electron microscope (FEGSEM) at high resolution. The highly crosslinked UHMWPEs had significantly lower wear volumes than the non-crosslinked UHMWPEs. No significant difference was found in the percentage number and percentage volume of the particles in different size ranges from any of the materials. They had similar values of specific biological activity. The functional biological activity (FBA), which takes into account the wear volume and specific biological activity, showed that the highly crosslinked UHMWPEs had lower FBAs due to their lower wear volume.
Hasbi, A, Nguyen, T, Fan, T, Cheng, R, Rashid, A, Alijaniaram, M, Rasenick, MM, O'Dowd, BF & George, SR 2007, 'Trafficking of Preassembled Opioid μ−δ Heterooligomer−Gz Signaling Complexes to the Plasma Membrane: Coregulation by Agonists', Biochemistry, vol. 46, no. 45, pp. 12997-13009.
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The cellular site of formation, Gα-coupling preference, and agonist regulation of μ-δ opioid receptor (OR) heterooligomers were studied. Bioluminescence resonance energy transfer (BRET) showed that μ-δ OR heterooligomers, composed of preformed μ and δ homooligomers, interacted constitutively in the endoplasmic reticulum (ER) with Gα-proteins forming heteromeric signaling complexes before being targeted to the plasma membrane. Compared to μOR homooligomers, the μ-δ heterooligomers showed higher affinity and efficiency of interaction for Gz over Gi, indicating a switch in G-protein preference. Treatment with DAMGO or deltorphin II led to coregulated internalization of both receptors, whereas DPDPE and DSLET had no effect on μ-δ internalization. Staggered expression resulted in non-interacting μ and δ receptors, even though both receptors were colocalized at the cell surface. Agonists failed to induce BRET between staggered receptors, and resulted in internalization solely of the receptor targeted by agonist. Thus, μ-δOR heterooligomers form and preferentially associate with Gz to generate a signaling complex in the ER, and have a distinct agonist-internalization profile compared to either μ or δ homooligomers. © 2007 American Chemical Society.
Jabbari, E, Tavakoli, J & Sarvestani, AS 2007, 'Swelling characteristics of acrylic acid polyelectrolyte hydrogel in a dc electric field', Smart Materials and Structures, vol. 16, no. 5, pp. 1614-1620.
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Khosroshahi, ME, Mahmoodi, M & Tavakoli, J 2007, 'Characterization of Ti6Al4V implant surface treated by Nd:YAG laser and emery paper for orthopaedic applications', Applied Surface Science, vol. 253, no. 21, pp. 8772-8781.
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Khosroshahi, ME, Tavakoli, J & Mahmoodi, M 2007, 'Analysis of Bioadhesivity of Osteoblast Cells on Titanium Alloy Surface Modified by Nd:YAG Laser', The Journal of Adhesion, vol. 83, no. 2, pp. 151-172.
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Konstantynowicz, J, Nguyen, TV, Kaczmarski, M, Jamiolkowski, J, Piotrowska-Jastrzebska, J & Seeman, E 2007, 'Fractures during growth: potential role of a milk-free diet', Osteoporosis International, vol. 18, no. 12, pp. 1601-1607.
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Liu, PY, Beilin, J, Meier, C, Nguyen, TV, Center, JR, Leedman, PJ, Seibel, MJ, Eisman, JA & Handelsman, DJ 2007, 'Age-Related Changes in Serum Testosterone and Sex Hormone Binding Globulin in Australian Men: Longitudinal Analyses of Two Geographically Separate Regional Cohorts', The Journal of Clinical Endocrinology & Metabolism, vol. 92, no. 9, pp. 3599-3603.
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Abstract Background: Cross-sectional studies from different populations show a variable decline in blood testosterone concentrations as men age. Few population representative cohorts have been followed up over time. Objective: The objective of the study was to quantify longitudinally the change in serum testosterone and SHBG concentrations with age in two well-defined, representative but geographically widely separated regional Australian cohorts. Subjects and Setting: The Busselton cohort comprises individuals aged 18–90 yr residing in Western Australia assessed prospectively since 1981. Sera were assayed from 910 men, from whom further samples were available 14 yr later in 480. The Dubbo cohort involves individuals aged 61–90 yr living in Eastern Australia. Baseline sera were collected from 610 men and additional sera on a second (n = 370) and third (n = 200) occasion from 1989 to 2004. Men from both cohorts are community dwelling and of predominately European origin. Results: Longitudinal analyses show the following: 1) total testosterone declines comparably (P > 0.9) by 1.3% (Busselton) and 0.9% (Dubbo) per annum with the same rates of decline when analyses were restricted to men older than 60 yr of age; 2) annual changes in SHBG were also very similar in age-restricted analyses (2.3% vs. 2.5%, P = 0.48); and 3) the annual increase in SHBG was steeper in middle-aged and older men (P < 10−3vs. young men). These longitudinal changes were all up to 4-fold greater in magnitude, compared with cross-sectional analyses of baseline data. Conclusion: In two separate regional Australian populations, blood testosterone fell and SHBG increased comparably with age. Age-related changes in blood testosterone and SHBG previously described in urban-dwelling men are the same in me...
Makovey, J, Nguyen, TV, Naganathan, V, Wark, JD & Sambrook, PN 2007, 'Genetic Effects on Bone Loss in Peri- and Postmenopausal Women: A Longitudinal Twin Study', Journal of Bone and Mineral Research, vol. 22, no. 11, pp. 1773-1780.
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Abstract This longitudinal twin study was designed to assess the heritability of bone loss in peri- and postmenopausal women. A sample of 724 female twins was studied. Baseline and repeat BMD measurements were performed. Results of genetic model-fitting analysis indicated genetic effects on bone loss account for ∼40% of the between-individual variation in bone loss at the lumbar spine, forearm, and whole body. Introduction: BMD and bone loss are important predictors of fracture risk. Although the heritability of peak BMD is well documented, it is not clear whether bone loss is also under genetic regulation. This study was designed to assess the heritability of bone loss in peri- and postmenopausal women. Materials and Methods: A sample of 724 female twins (177 monozygotic [MZ] and 185 dizygotic [DZ] pairs), 45–82 yr of age, was studied. Each individual had baseline BMD measurements at the lumbar spine, hip, forearm, and total body by DXA and at least one repeat measure, on average 4.9 yr later. Change in BMD (ΔBMD) was expressed as percent of gain or loss per year. Intraclass correlation coefficients for ΔBMD were calculated for MZ and DZ pairs. Genetic model-fitting analysis was conducted to partition the total variance of ΔBMD into three components: genetic (G), common environment (C), and specific environment, including measurement error (E). The index of heritability was estimated as the ratio of genetic variance over total variance. Results: The mean annual ΔBMD was –0.37 ± 1.43% (SD) per year at the lumbar spine, −0.27 ± 1.32% at the total hip, −0.77 ± 1.66% at the total forearm, −0.36 ± 1.56% at the femoral neck, and −0.16 ± 0.81% at the whole body. Intraclass correlation coefficients were significantly higher in MZ than in DZ twins for all studied parameters, except at the hip sites. Results of genetic m...
Nguyen, ND, Ahlborg, HG, Center, JR, Eisman, JA & Nguyen, TV 2007, 'Residual Lifetime Risk of Fractures in Women and Men', Journal of Bone and Mineral Research, vol. 22, no. 6, pp. 781-788.
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Abstract In a sample of 1358 women and 858 men, ≥60 yr of age who have been followed-up for up to 15 yr, it was estimated that the mortality-adjusted residual lifetime risk of fracture was 44% for women and 25% for men. Among those with BMD T-scores ≤ −2.5, the risks increased to 65% in women and 42% in men. Introduction: Risk assessment of osteoporotic fracture is shifting from relative risk to an absolute risk approach. Whereas BMD is a primary predictor of fracture risk, there has been no estimate of mortality-adjusted lifetime risk of fracture by BMD level. The aim of the study was to estimate the residual lifetime risk of fracture (RLRF) in elderly men and women. Materials and Methods: Data from 1358 women and 858 men ≥60 yr of age as of 1989 of white background from the Dubbo Osteoporosis Epidemiology Study were analyzed. The participants have been followed for up to 15 yr. During the follow-up period, incidence of low-trauma, nonpathological fractures, confirmed by X-ray and personal interview, were recorded. Incidence of mortality was also recorded. BMD at the femoral neck was measured by DXA (GE-LUNAR) at baseline. Residual lifetime risk of fracture from the age of 60 was estimated by the survival analysis taking into account the competing risk of death. Results: After adjusting for competing risk of death, the RLRF for women and men from age 60 was 44% (95% CI, 40–48) and 25% (95% CI, 19–31), respectively. For individuals with osteoporosis (BMD T-scores ≤ −2.5), the mortality-adjusted lifetime risk of any fracture was 65% (95% CI, 58–73) for women and 42% (95% CI, 24–71) for men. For the entire cohort, the lifetime risk of hip fracture was 8.5% (95% CI, 6–11%) for women and 4% (95% CI, 1.3–5.4%) for men; risk of symptomatic vertebral fracture was 18% (95% CI, 15–21%) for women and 11% (95% CI, 7–14%) f...
Nguyen, ND, Center, JR, Eisman, JA & Nguyen, TV 2007, 'Bone Loss, Weight Loss, and Weight Fluctuation Predict Mortality Risk in Elderly Men and Women', Journal of Bone and Mineral Research, vol. 22, no. 8, pp. 1147-1154.
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Abstract Low baseline BMD, rate of BMD loss, weight loss, and weight fluctuation are significant predictors of all-cause mortality in elderly men and women, independent of each other and of age, incident fracture, and concomitant diseases. Introduction: Although low BMD has been shown to be associated with mortality in women, the effect of BMD is affected by weight and weight change and the contribution of these factors to mortality risk, particularly in men, is not known. This study examined the association between baseline BMD, rate of bone loss, weight loss, and weight fluctuation and all-cause mortality risk in elderly men and women. Materials and Methods: Data from 1059 women and 644 men, ≥60 years of age (as of 1989), of white background who participated in the Dubbo Osteoporosis Epidemiology Study were analyzed. All-cause mortality was recorded annually between 1989 and 2004. BMD at the femoral neck was measured by DXA (GE-LUNAR) at baseline and at approximately every 2 yr afterward. Data on incident osteoporotic fractures and concomitant diseases, including cardiovascular diseases, all types of cancer, and type I/II diabetes mellitus, was also recorded. Results: In the multivariable Cox's proportional hazards model with adjustment for age, incident fractures, and concomitant diseases, the following variables were independent risk factors of all-cause mortality in men: rate of BMD loss of at least 1%/yr, rate of weight loss of at least 1%/yr, and weight fluctuation (defined by the CV) of at least 3%. In women, in addition to the significant factors observed in men, lower baseline BMD was also an independent risk factor of mortality. In both sexes, baseline weight was not an independent and significant predictor of mortality risk. Approximately 36% and 22% of deaths in women and men, respectively, were att...
Nguyen, ND, Eisman, JA, Center, JR & Nguyen, TV 2007, 'Risk Factors for Fracture in Nonosteoporotic Men and Women', The Journal of Clinical Endocrinology & Metabolism, vol. 92, no. 3, pp. 955-962.
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Context and Objective: It is not known which factors are associated with fracture in nonosteoporotic elderly. The aim of this study was to assess the association between fall-related risk factors and fracture risk in men and women without osteoporosis. D
Nguyen, ND, Wang, CY, Eisman, JA & Nguyen, TV 2007, 'On the association between statin and fracture: A Bayesian consideration', Bone, vol. 40, no. 4, pp. 813-820.
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Background: The association between statin use and fracture risk is controversial, due to conflicting findings from previous studies. This study utilized the Bayesian approach to combine existing evidence and update the association with consideration of
Nguyen, TV 2007, 'Individualization of osteoporosis risk', Osteoporosis International, vol. 18, no. 9, pp. 1153-1156.
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Nguyen, TV, Meier, C, Center, JR, Eisman, JA & Seibel, MJ 2007, 'Bone turnover in elderly men: relationships to change in bone mineral density', BMC Musculoskeletal Disorders, vol. 8, no. 1.
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Background: It is not clear whether bone turnover markers can be used to make inference regarding changes in bone mineral density (BMD) in untreated healthy elderly men. The present study was designed to address three specific questions: (i) is there a r
O’Dowd, BF, Alijaniaram, M, Ji, X, Nguyen, T, Eglen, RM & George, SR 2007, 'Using Ligand-Induced Conformational Change to Screen for Compounds Targeting G-Protein-Coupled Receptors', SLAS Discovery, vol. 12, no. 2, pp. 175-185.
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The authors describe a novel drug strategy designed as a primary screen to discover either antagonist or agonist compounds targeting G-protein-coupled receptors (GPCRs). The incorporation of a nuclear localization sequence (NLS, a 5 amino acid substitution), in a location in helix 8 of the GPCR structure, resulted in ligand-independent receptor translocation from the cell surface to the nucleus. Blockade of the GPCR-NLS translocation from the cell surface was achieved by either antagonist or agonist treatments, each achieving their result in a sensitive concentration-dependent manner. GPCR-NLS translocation and blockade occurred regardless of the identity of the G-protein-coupling, and thus this assay is also ideally suited for identification of compounds targeting orphan GPCRs. The GPCR-NLS trafficking was visualized by fusion to fluorescent detectable proteins. Quantification of this effect was measured by determining the density of cell surface receptors, using enzyme fragment complementation in a manner suitable for high-throughput screening. Thus, the authors have developed a cellular assay for GPCRs suitable for compound screening without requiring prior identification of an agonist or knowledge of G-protein-coupling.
Pongchaiyakul, C, Nguyen, TV, Wanothayaroj, E, Karusan, N & Klungboonkrong, V 2007, 'Prevalence of metabolic syndrome and its relationship to weight in the Thai population.', J Med Assoc Thai, vol. 90, no. 3, pp. 459-467.
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BACKGROUND: Although the prevalence of the metabolic syndrome (MetS) has been well-documented in Western Caucasian populations, there are few studies in non-Caucasian populations. The objectives of the present study were to estimate the prevalence of MetS and to find an optimal BMI cut-off value for defining obesity in the Thai population. MATERIAL AND METHOD: A sample of 307 men and 295 healthy women aged between 20 and 90 years (average age of 45 years) who came for a health check-up clinic in Khon Kaen, a northeast province of Thailand, were studied. The present study was conducted between 2003 and 2004. The modified ATP III criteria were used to estimate the age-and-sex specific prevalence of MetS, in which a BMI of > or = 27 kg/m(2) for men and 25 kg/m(2) for women were used in place of waist circumference. In the Thai population, these BMI cut-offs were equivalent to a percent body fat of 25% and 35% in men and women respectively. RESULTS: The overall prevalence of MetS was 15%, with no significant differences between men (15.3%) and women (14.6%). In men, the prevalence increased from 9.5% among the 20-39 age group to 24.7% among the 50+ age groups. In women, the respective prevalence was 7% and 29.5%. When BMI was removed from the classification ofMetS, the overall prevalence of 'MetS-without-BMI' (still defined by the presence of at least 3 abnormalities) in both men and women was 7.8%. However the prevalence of MetS-without-BMI increased with higher BMI levels: among those with BMI < 25, the prevalence was 4.6% in men and 5.0% in women; among those with BMI > or = 25, the prevalence was 13% in men and 16% in women. CONCLUSION: The prevalence of MetS in this semi-rural Thai population was 15%, which is as common as in Caucasian populations. In the Thai population, obesity was a major component of MetS.
Pongchaiyakul, C, Panichkul, S, Songpatanasilp, T & Nguyen, TV 2007, 'A nomogram for predicting osteoporosis risk based on age, weight and quantitative ultrasound measurement', Osteoporosis International, vol. 18, no. 4, pp. 525-531.
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Schwarz, DS, Hutvagner, G, Du, T, Xu, Z, Aronin, N & Zamore, PD 2007, 'Asymmetry in the assembly of the RNAi enzyme complex (Reprinted from Cell, vol 115, pg 199-208, 2003)', CELL, vol. 131, no. 4, pp. 30-40.
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A key step in RNA interference (RNAi) is assembly of the RISC, the protein-siRNA complex that mediates target RNA cleavage. Here, we show that the two strands of an siRNA duplex are not equally eligible for assembly into RISC. Rather, both the absolute a
Tavakoli, J, Khosroshahi, ME & Mahmoodi, M 2007, 'Characterization of Nd: YAG laser radiation effects on Ti6Al4V physico-chemical properties: An in vivo study', International Journal of Engineering, Transactions B: Applications, vol. 20, no. 1, pp. 1-11.
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The effect of a Nd: YAG laser (1064 nm) has been studied on Ti6Al4V alloy in terms of optical and physical parameters for biomedical applications. The superior surface microhardness hardness (i.e. 377 VHN) is attributed to grain refinement associated with laser melting and rapid solidification. The electrochemical property, mainly pitting corrosion resistance, has been carried out in Hanks salt balanced physiological solution using standard potentiodynamic polarization testing. At the optimium laser treating fluence (140 Jcm -2), the EDX spectroscopy showed a decrease of about 30 % in the vanadium and the contact angle measurements also indicated an improved surface wettability seen in the characteristics with a contact angle of 35°. Finally, Cell spreading on the implanted specimens was analyzed by SEM and their condition in a specific area was studied for 10 cells for three separate regions on the same specimen using Image J Program software. The in vivo tests provided some useful clinical and pathological information regarding tissue response to the implants with different surface topography.
