Biodiesel production from eggshells derived bio-nano CaO catalyst - microemulsion fuel blends for up-gradation of biodiesel.

The utilization of bio-oil derived from biomass presents a promising alternative to fossil fuels, though it faces challenges when directly applied in diesel engines. Microemulsification has emerged as a viable strategy to enhance bio-oil properties, facilitating its use in hybrid fuels. This study explores the microemulsification of Jatropha bio-oil with ethanol, aided by a surfactant, to formulate a hybrid liquid fuel. Additionally, a bio-nano CaO heterogeneous catalyst synthesized from eggshells is employed to catalyse the production of Jatropha biodiesel from the microemulsified fuel using microwave irradiation. The catalyst is characterized through UV-Vis, XRD, and SEM analysis. The investigation reveals a significant reduction in CO, CO2, and NOX emissions with the utilization of microemulsion-based biodiesel blends. Various blends of conventional diesel, Jatropha biodiesel, and ethanol are prepared with different ethanol concentrations (5, 10, and 20 wt%). Engine performance parameters, including fuel consumption, NOX emission, and brake specific fuel consumption, are analyzed. Results indicate that the conventional diesel/Jatropha biodiesel/ethanol (10 wt%) blend exhibits superior performance compared to conventional diesel, Jatropha biodiesel, and other blends. The fuel consumption of the conventional diesel/Jatropha biodiesel/ethanol (10 wt%) blend is measured at 554.6 g/h, surpassing that of conventional diesel and other biodiesel blends. The presence of water (0.14 %) in the blend reduces the heating value, consequently increasing the energy requirement. CO and CO2 emissions for the conventional diesel/Jatropha biodiesel/ethanol (10 wt%) blend are notably lower compared to conventional C-18 hydrocarbons and various biodiesel blends. These findings accentuate the efficacy of the microemulsion process in enhancing fuel characteristics and reducing emissions. Further investigations could explore optimizing the emulsifying agents and their impact on engine performance and emission characteristics, contributing to the advancement of sustainable fuel technologies.

Identification of suitable catalyst among HZSM-5, HY and γ-Al2O3 to obtain upgraded pyrolysis oil with augmented liquid oil yield.

This study examines catalytic ability of various zeolite materials in converting discarded tire pyrolyzed oil by employing a moderate sized pyrolysis plant for a 10 L working volume. The yield of liquid fractions from γ-Al2O3 was greater than that of HZSM-5 and HY, whereas the least amount of condensates was formed when catalyst was not present. When enhanced tire waste pyrolysis oil was analyzed using Fourier transform infrared spectroscopy with an alumina catalyst, the stretching bands corresponding to aromatic and non-aromatic compounds were visible. The results of GC-MS examinations confirm this even more. The γ-Al2O3 catalyst yielded a higher amount of liquid oil than the other two catalysts. The cyclic unsaturated fragment percentages in liquids were decreased by the catalysts used to 53.9% with HY, 59.0% with γ-Al2O3, and 62.2% with HZSM-5, which produced aromatic chemicals. Nitrogen adsorption desorption analysis revealed that γ-Al2O3 has an enhanced surface area of 635 m2/g which improved its catalytic performance. The cracked liquid oil had viscosity (10.36 cSt), values of pour and flash temperatures of -2.2 °C and 41 °C respectively, analogous to petroleum diesel. The upgraded pyrolysis oil (10%) is blended with gasoline (90%) and emission analysis was performed. Moreover, liquid oil needs post treatment (refining) for its use as energy source in transportation application. The novelty of this research is in its comparative analysis of multiple catalysts under controlled conditions using a small pilot-scale pyrolysis reactor, which provides insights into optimizing the pyrolysis process for industrial applications.

Synthesis of zero valent copper/iron nanoparticles using Piper betle leaves for the removal of pharmaceutical contaminant atorvastatin.

In this study, bimetallic Cu-Fe nanoparticles were synthesized using the green approach with Piper betle leaves, and the removal efficiency of one of the pharmaceutical compounds, Atorvastatin, was investigated. UV, SEM, FTIR, EDAX, particle size, and zeta potential measurements were used to confirm nanoparticle fabrication. The removal efficiency of Atorvastatin (10 mg/L) by bimetallic Cu-Fe nanoparticles was 67% with a contact time of 30 min at pH 4, the adsorbent dosage of 0.2 g/L, and stirring at 100 rpm. Piper betle bimetallic Cu-Fe nanoparticles have demonstrated excellent stability, reusability, and durability, even after being reused five times. Furthermore, the synthesized bimetallic Cu-Fe nanoparticles demonstrated remarkable antimicrobial properties against gram-negative strains such as Escherichia coli and Klebsiella pneumoniae, gram-positive strains such as Staphylococcus aureus and Bacillus subtilis, and fungi such as Aspergillus niger. In addition, the antioxidant properties of the synthesized bimetallic Cu-Fe nanoparticles were assessed using the DPPH radical scavenging assay. The results indicated that the nanoparticles had good antioxidant activity. Thus, using Piper betle extract to make Cu-Fe nanoparticles made the procedure less expensive, chemical-free, and environmentally friendly, and the synthesized bimetallic Cu-Fe nanoparticles helped remove the pharmaceutical compound Atorvastatin from wastewater.

Bridge percolation: electrical connectivity of discontinued conducting slabs by metallic nanowires.

The properties of nanostructured networks of conductive materials have been extensively studied under the lens of percolation theory. In this work, we introduce a novel type of local percolation phenomenon used to investigate the conduction properties of a new hybrid material that combines sparse metallic nanowire networks and fractured conducting thin films on flexible substrates. This original concept could potentially lead to the design of a novel composite transparent conducting material. Using a complementary approach including formal analytical derivations, Monte Carlo simulations and electrical circuit representation for the modelling of bridged-percolating nanowire networks, we unveil the key relations between linear crack density, nanowire length and network areal mass density that ensure electrical percolation through the hybrid. The proposed theoretical model provides key insights into the conduction mechanism associated with the original concept of bridge percolation in random nanowire networks.

In vitro analysis of iron oxide (Fe3O4) nanoparticle mediated degradation of polycyclic aromatic hydrocarbons (PAHs) and their antimicrobial activity.

To degrade anthracene, magnetite nanoparticles were produced using a simple co-precipitation process. The fabricated nanoparticles have been analyzed for structural and optical properties. XRD examination revealed that the produced Fe3O4 nanoparticles were cubic phase, having a mean crystallite dimension of 18.84 nm. DLS determined the hydrodynamic diameter of Fe3O4 nanoparticles to be 182 nm. UV-Vis research revealed that Fe3O4 nanoparticles absorb at 390 nm. A peak at 895 cm-1 in the FT-IR study indicated the metal-oxygen connection. The synthesized Fe3O4 nanoparticles demonstrated an effective photocatalytic performance towards anthracene degradation and was found to be 86.55%. Furthermore, Fe3O4 nanoparticles showed the highest antimicrobial activity against Bacillus subtilis was 19.43 mm. The present study is the first and foremost study determining the dual role of Fe3O4 nanoparticles towards bioremediation and biomedical applications.

Video assisted thoracoscopy or laparoscopy for enucleation of esophageal leiomyoma: A seven-year single center experience of 75 cases.

OBJECTIVE: Leiomyoma is the most common benign tumor of the esophagus. Extra mucosal enucleation is the standard treatment. Herein we evaluated the feasibility and the outcomes of Minimally Invasive Surgery (MIS) using video-assisted thoracoscopic (VATS) or laparoscopic surgery (VALS) for esophageal leiomyoma enucleation. SUBJECTS AND METHODS: Retrospective study of patients who were treated via VATS or VALS for esophageal leiomyoma enucleation in "Hanoi Viet Duc Hospital" from 2010 to 2017 by the same operator. The operative approach, tumor size, complications and outcomes after surgery were recorded. RESULTS: Seventy-five patients were included. Mean age was 41.9 (range 20-68) years. The male/female sex ratio was 2.1:1. Fifty-five patients had clinical symptoms (73.3%). Tumors were identified in the upper third (12%), middle third (51%), and lower third (37%) of the esophagus. Mean tumor size was 3.7 (range 2-11) cm. VALS enucleation was performed in 23 patients who had leiomyoma located near the cardia (gastroesophageal junction or abdominal esophagus). The remaining 52 patients underwent right (n=42) or left VATS (n=10). Five patients (6.7%) sustained esophageal mucosa injury during dissection, repaired by MIS without late morbidity. A mini-incision (2 mini-laparotomies and 1 thoracotomy) was required in three patients (4%) due to large tumor size or mucosal injury. The mean operative time was 105min in VATS and 174min in VALS. No major perioperative surgical or medical complications were reported. The mean duration of hospital stay was 7.2 (range 5-12) days. CONCLUSIONS: MIS enucleation of esophageal leiomyoma is technically safe and associated with a high therapeutic success rate with low medico-surgical morbidity. VATS could be applied for almost all esophageal leiomyoma tumors; however, the VALS approach was preferred for tumors located near the gastroesophageal junction in order to create an anti-reflux valve after enucleation.

Rubisco condensate formation by CcmM in ß-carboxysome biogenesis.

Cells use compartmentalization of enzymes as a strategy to regulate metabolic pathways and increase their efficiency1. The α- and ß-carboxysomes of cyanobacteria contain ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco)-a complex of eight large (RbcL) and eight small (RbcS) subunits-and carbonic anhydrase2-4. As HCO3- can diffuse through the proteinaceous carboxysome shell but CO2 cannot5, carbonic anhydrase generates high concentrations of CO2 for carbon fixation by Rubisco6. The shell also prevents access to reducing agents, generating an oxidizing environment7-9. The formation of ß-carboxysomes involves the aggregation of Rubisco by the protein CcmM10, which exists in two forms: full-length CcmM (M58 in Synechococcus elongatus PCC7942), which contains a carbonic anhydrase-like domain8 followed by three Rubisco small subunit-like (SSUL) modules connected by flexible linkers; and M35, which lacks the carbonic anhydrase-like domain11. It has long been speculated that the SSUL modules interact with Rubisco by replacing RbcS2-4. Here we have reconstituted the Rubisco-CcmM complex and solved its structure. Contrary to expectation, the SSUL modules do not replace RbcS, but bind close to the equatorial region of Rubisco between RbcL dimers, linking Rubisco molecules and inducing phase separation into a liquid-like matrix. Disulfide bond formation in SSUL increases the network flexibility and is required for carboxysome function in vivo. Notably, the formation of the liquid-like condensate of Rubisco is mediated by dynamic interactions with the SSUL domains, rather than by low-complexity sequences, which typically mediate liquid-liquid phase separation in eukaryotes12,13. Indeed, within the pyrenoids of eukaryotic algae, the functional homologues of carboxysomes, Rubisco adopts a liquid-like state by interacting with the intrinsically disordered protein EPYC114. Understanding carboxysome biogenesis will be important for efforts to engineer CO2-concentrating mechanisms in plants15-19.

Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes.

The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.

Phylogeographic and genome-wide investigations of Vietnam ethnic groups reveal signatures of complex historical demographic movements.

The territory of present-day Vietnam was the cradle of one of the world's earliest civilizations, and one of the first world regions to develop agriculture. We analyzed the mitochondrial DNA (mtDNA) complete control region of six ethnic groups and the mitogenomes from Vietnamese in The 1000 Genomes Project (1000G). Genome-wide data from 1000G (~55k SNPs) were also investigated to explore different demographic scenarios. All Vietnamese carry South East Asian (SEA) haplotypes, which show a moderate geographic and ethnic stratification, with the Mong constituting the most distinctive group. Two new mtDNA clades (M7b1a1f1 and F1f1) point to historical gene flow between the Vietnamese and other neighboring countries. Bayesian-based inferences indicate a time-deep and continuous population growth of Vietnamese, although with some exceptions. The dramatic population decrease experienced by the Cham 700 years ago (ya) fits well with the Nam tien ("southern expansion") southwards from their original heartland in the Red River Delta. Autosomal SNPs consistently point to important historical gene flow within mainland SEA, and add support to a main admixture event occurring between Chinese and a southern Asian ancestral composite (mainly represented by the Malay). This admixture event occurred ~800 ya, again coinciding with the Nam tien.

Polar interface phonons in ionic toroidal systems.

We use the dielectric continuum model to obtain the polar (Fuchs-Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus.

Accelerated bone loss and increased post-fracture mortality in elderly women and men.

UNLABELLED: Bone loss, a fracture risk factor, may play a role in post-fracture mortality. We found accelerated bone loss (≥1.31 % bone loss/year for women and ≥1.35 % bone loss/year for men) associated with 44-77 % increased mortality. It remains unclear whether bone loss is a marker or plays a role in mortality. INTRODUCTION: Osteoporotic fractures are associated with increased mortality although the cause is unknown. Bone loss, a risk factor for osteoporotic fracture is also associated with increased mortality, but its role in mortality risk post-fracture is unclear. This study aimed to examine post-fracture mortality risk according to levels of bone loss. METHODS: Community-dwelling participants aged 60+ from Dubbo Osteoporosis Epidemiology Study with incident fractures were followed from 1989 to 2011. Kaplan-Meier survival curves were constructed according to bone loss quartiles. Cox proportional hazard models were used to determine the effect of bone loss on mortality. RESULTS: There were 341 women and 106 men with ≥2 BMD measurements. The rate of bone loss was similar for women and men (women mean -0.79 %/year, highest bone loss quartile -1.31 %/year; men mean -0.74 %/year, highest quartile -1.35 %/year). Survival was lowest for the highest quartile of bone loss for women (p < 0.005) and men (p = 0.05). When analysed by fracture type, the association of bone loss with mortality was observed for vertebral (highest vs lower 3 quartiles of bone loss, women p = 0.03 and men p = 0.02) and non-hip non-vertebral fractures in women (p < 0.0001). Bone loss did not play an additional role in mortality risk following hip fractures. Importantly, overall, rapid bone loss was associated with 44-77 % increased mortality risk after multiple variable adjustment. CONCLUSION: Rapid bone loss was an independent predictor of post-fracture mortality risk in both women and men. The association of bone loss and post-fracture mortality was predominantly observed following vertebral fracture in both women and men and non-hip non-vertebral fracture in women. It remains to be determined whether bone loss is a marker or plays a role in the mortality associated with fractures.

Metallic nanowire networks: effects of thermal annealing on electrical resistance.

Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 Ω sq(-1). Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays.

Association between hypertension and fragility fracture: a longitudinal study.

UNLABELLED: Hypertension is an independent risk factor for osteoporosis and osteoporotic fracture in postmenopausal women. INTRODUCTION: Although hypertension has been suggested to be associated with increased fracture risk, it is not clear whether the association is independent of bone mineral density (BMD). The present study sought to examine the interrelationships between hypertension, BMD, and fracture risk. METHODS: The study included 1,032 men and 1,701 women aged 50 years and older who were participants in the Dubbo Osteoporosis Epidemiology Study. BMD at the femoral neck and lumbar spine was measured by dual energy X-ray absorptiometry (GE-LUNAR Corp., Madison, WI, USA). The presence of hypertension was ascertained by direct interview and verification through clinical history. The incidence of fragility fractures was ascertained by X-ray report during the follow-up period (1989-2008). The Cox proportional hazards model was used to assess the association between hypertension and fracture risk. RESULTS: Women with hypertension had lower BMD at the femoral neck (0.79 versus 0.82 g/cm(2), P = 0.02) than those without the disease. After adjusting for BMD and covariates, hypertension was an independent risk factor for fragility fracture [hazard ratio (HR), 1.49; 95% CI, 1.13-1.96]. In men, hypertension was associated with higher femoral neck BMD (0.94 versus 0.92 g/cm(2), P = 0.02), but the association between hypertension and fracture risk did not reach statistical significance. CONCLUSION: Hypertension is associated with increased fracture risk in women, and the association is independent of BMD.

Quantitative ultrasound and fracture risk prediction in non-osteoporotic men and women as defined by WHO criteria.

UNLABELLED: This study sought to determine the association between calcaneal quantitative ultrasound (QUS) and fracture risk in individuals without osteoporosis according to the World Health Organization criteria (i.e., BMD T-score > -2.5). We found that calcaneal QUS is an independent predictor of fracture risk in women with non-osteoporotic bone mineral density (BMD). INTRODUCTION: More than 50 % of women and 70 % of men who sustain a fragility fracture have BMD above the osteoporotic threshold (T-score > -2.5). Calcaneal QUS is associated with fracture risk. This study aimed to test the hypothesis that low calcaneal QUS is associated with increased fracture risk in individuals with non-osteoporotic BMD. METHODS: We included 312 women and 390 men aged 62-90 years with BMD T-score > -2.5 at femoral neck. QUS was measured in broadband ultrasound attenuation (BUA) at the calcaneus using a CUBA sonometer. BMD was measured at the femoral neck (FNBMD) by dual energy X-ray absorptiometry using GE Lunar DPX-L densitometer. The incidences of any fragility fracture were ascertained by X-ray reports during the follow-up period from 1994 to 2011. RESULTS: Of the 702 participants, 26 % of women (n = 80/312) and 14 % of men (n = 53/390) experienced at least one fragility fracture during the follow-up period. In women, after adjusting for covariates, increased risk of any fracture was significantly associated with decreased BUA (HR = 1.50; 95 % CI, 1.13-1.99). Compared with that of FNBMD, the models with BUA, in women, had greater AUC (0.71, 0.85, 0.71 for any, hip and vertebral fracture, respectively), and yielded a net reclassification improvement of 16.4 % (P = 0.009) when combined with FNBMD. In men, BUA was not significantly associated with fracture risk before and after adjustment. CONCLUSION: These results suggest that calcaneal BUA is an independent predictor of fracture risk in women with non-osteoporotic BMD.

Vegetarianism, bone loss, fracture and vitamin D: a longitudinal study in Asian vegans and non-vegans.

BACKGROUND/OBJECTIVES: The effect of vegan diet on bone loss has not been studied. The aim of this study was to examine the association between veganism and bone loss in postmenopausal women. SUBJECTS/METHODS: The study was designed as a prospective longitudinal investigation with 210 women, including 105 vegans and 105 omnivores. Femoral neck (FN) bone mineral density (BMD) was measured in 2008 and 2010 by dual-energy X-ray absorptiometry (Hologic QDR4500). The incidence of vertebral fracture was ascertained by X-ray report. Serum levels of C-terminal telopeptide of type I collagen (ßCTX) and N-terminal propeptide of type I procollagen (PINP) were measured by Roche Elecsys assays. Serum concentration of 25-hydroxyvitamin D and parathyroid hormone were measured by electrochemiluminescence. RESULTS: Among the 210 women who initially participated in the study in 2008, 181 women had completed the study and 29 women were lost to follow-up. The rate of loss in FN BMD was -1.91±3.45%/year in omnivores and -0.86±3.81%/year (P=0.08) in vegans. Lower body weight, higher intakes of animal protein and lipid, and corticosteroid use were associated with greater rate of bone loss. The 2-year incidence of fracture was 5.7% (n=5/88) in vegans, which was not significantly different from omnivores (5.4%, n=6/93). There were no significant differences in ßCTX and PINP between vegans and omnivores. The prevalence of vitamin D insufficiency in vegans was higher than in omnivores (73% versus 46%; P=0.0003). CONCLUSIONS: Vegan diet did not have adverse effect on bone loss and fracture. Corticosteroid use and high intakes of animal protein and animal lipid were negatively associated with bone loss.

Vitamin D status and parathyroid hormone in a urban population in Vietnam.

UNLABELLED: In this cross-sectional study in Vietnam, the prevalence of vitamin D insufficiency was 46% in adult women and 20% in adult men. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued. INTRODUCTION: Vitamin D insufficiency is adversely associated with health outcomes. Vitamin D status in Asian populations is not well documented. This study sought to assess vitamin D status and its relationship to parathyroid hormone in a Vietnamese population. METHODS: This cross-sectional study involved 205 men and 432 women aged 18-87 years, who were randomly sampled from various districts in Ho Chi Minh City (Vietnam) according to a proportional sampling scheme. Serum concentration of 25(OH)D and PTH were measured by the Electrochemiluminescence immunoassay on the Roche Elecsys 10100/201 system (Roche Diagnosis Elecsys). Vitamin D insufficiency was quantified as serum 25(OH)D levels below 30 ng/ml (75 nmol/L). RESULTS: The average age for men and women was 43.8 ± 18.4 years (mean ± SD) and 47.7 ± 17.1 years, respectively. The mean 25(OH)D concentration in men (36.8 ± 10.2 ng/mL) was significantly higher than in women (30.1 ± 5.9; P < 0.0001). The prevalence of vitamin D insufficiency in men was 20% (41/205) which was significantly lower than in women (46%, 199/432). Age, height and weight were independent predictors of 25(OH)D concentrations, and the three factors explained 15% and 5% of variance in 25(OH)D in men and women, respectively. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued. CONCLUSIONS: These data show that vitamin D insufficiency is common even in tropical region, and that women had a greater risk of vitamin D insufficiency than men. These data suggest that an elevation in PTH cannot be used as a marker for vitamin D deficiency.

Identification of undiagnosed type 2 diabetes by systolic blood pressure and waist-to-hip ratio.

AIMS/HYPOTHESIS: We estimated the current prevalence of type 2 diabetes in the Vietnamese population and developed simple diagnostic models for identifying individuals at high risk of undiagnosed type 2 diabetes. METHODS: The study was designed as a cross-sectional investigation with 721 men and 1,421 women, who were aged between 30 and 72 years and were randomly sampled from Ho Chi Minh City (formerly Saigon) in Vietnam. A 75 g oral glucose tolerance test to assess fasting and 2 h plasma glucose concentrations were determined for each individual. The ADA diagnostic criteria were used to determine the prevalence of type 2 diabetes. WHR and blood pressure were also measured in all individuals. RESULTS: The prevalence of type 2 diabetes was 10.8% in men and 11.7% in women. Higher WHR and blood pressure were independently associated with a greater risk of type 2 diabetes. Compared with participants without central obesity and hypertension, the odds of diabetes was increased by 6.4-fold (95% CI 3.2-13.0) in men and 4.1-fold (2.2-7.6) in women with central obesity and hypertension. Two nomograms were developed that help identify men and women at high risk of type 2 diabetes. CONCLUSIONS/INTERPRETATION: The current prevalence of type 2 diabetes in the Vietnamese population is high. Simple field measurements such as waist-to-hip ratio and systolic blood pressure can identify individuals at high risk of undiagnosed type 2 diabetes.

Prognosis of fracture: evaluation of predictive accuracy of the FRAX algorithm and Garvan nomogram.

UNLABELLED: We evaluated the prognostic accuracy of fracture risk assessment tool (FRAX) and Garvan algorithms in an independent Australian cohort. The results suggest comparable performance in women but relatively poor fracture risk discrimination in men by FRAX. These data emphasize the importance of external validation before widespread clinical implementation of prognostic tools in different cohorts. INTRODUCTION: Absolute risk assessment is now recognized as a preferred approach to guide treatment decision. The present study sought to evaluate accuracy of the FRAX and Garvan algorithms for predicting absolute risk of osteoporotic fracture (hip, spine, humerus, or wrist), defined as major in FRAX, in a clinical setting in Australia. METHODS: A retrospective validation study was conducted in 144 women (69 fractures and 75 controls) and 56 men (31 fractures and 25 controls) aged between 60 and 90 years. Relevant clinical data prior to fracture event were ascertained. Based on these variables, predicted 10-year probabilities of major fracture were calculated from the Garvan and FRAX algorithms, using US (FRAX-US) and UK databases (FRAX-UK). Area under the receiver operating characteristic curves (AUC) was computed for each model. RESULTS: In women, the average 10-year probability of major fracture was consistently higher in the fracture than in the nonfracture group: Garvan (0.33 vs. 0.15), FRAX-US (0.30 vs. 0.19), and FRAX-UK (0.17 vs. 0.10). In men, although the Garvan model yielded higher average probability of major fracture in the fracture group (0.32 vs. 0.14), the FRAX algorithm did not: FRAX-US (0.17 vs. 0.19) and FRAX-UK (0.09 vs. 0.12). In women, AUC for the Garvan, FRAX-US, and FRAX-UK algorithms were 0.84, 0.77, and 0.78, respectively, vs. 0.76, 0.54, and 0.57, respectively, in men. CONCLUSION: In this analysis, although both approaches were reasonably accurate in women, FRAX discriminated fracture risk poorly in men. These data support the concept that all algorithms need external validation before clinical implementation.

Development of prognostic nomograms for individualizing 5-year and 10-year fracture risks.

UNLABELLED: We have developed clinical nomograms for predicting 5-year and 10-year fracture risks for any elderly man or woman. The nomograms used age and information concerning fracture history, fall history, and BMD T-score or body weight. INTRODUCTION: Although many fracture risk factors have been identified, the translation of these risk factors into a prognostic model that can be used in primary care setting has not been well realized. The present study sought to develop a nomogram that incorporates non-invasive risk factors to predict 5-year and 10-year absolute fracture risks for an individual man and woman. METHODS: The Dubbo Osteoporosis Epidemiology Study was designed as a community-based prospective study, with 1358 women and 858 men aged 60+ years as at 1989. Baseline measurements included femoral neck bone mineral density (FNBMD), prior fracture, a history of falls and body weight. Between 1989 and 2004, 426 women and 149 men had sustained a low-trauma fracture (not including morphometric vertebral fractures). Two prognostic models based on the Cox's proportional hazards analysis were considered: model I included age, BMD, prior fracture and falls; and model II included age, weight, prior fracture and fall. RESULTS: Analysis of the area under the receiver operating characteristic curve (AUC) suggested that model I (AUC = 0.75 for both sexes) performed better than model II (AUC = 0.72 for women and 0.74 for men). Using the models' estimates, we constructed various nomograms for individualizing the risk of fracture for men and women. If the 5-year risk of 10% or greater is considered "high risk", then virtually all 80-year-old men with BMD T-scores < -1.0 or 80-year-old women with T-scores < -2.0 were predicted to be in the high risk group. A 60-year-old woman's risk was considered high risk only if her BMD T-scores < or = -2.5 and with a prior fracture; however, no 60-year-old men would be in the high risk regardless of their BMD and risk profile. CONCLUSION: These data suggest that the assessment of fracture risk for an individual cannot be based on BMD alone, since there are clearly various combinations of factors that could substantially elevate an individual's risk of fracture. The nomograms presented here can be useful for individualizing the short- and intermediate-term risk of fracture and identifying high-risk individuals for intervention to reduce the burden of fracture in the general population.

Discordance of longitudinal changes in bone density between densitometers.

UNLABELLED: This study examined the concordance in BMD measurement and longitudinal change in BMD between the GE Lunar Prodigy and GE Lunar DPX. Even though a high concordance between the densitometers was observed on a single measurement occasion, a significant discordance in longitudinal changes in BMD was observed. INTRODUCTION: Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) technology plays an important role in the diagnosis and management of osteoporosis. The present study examined the concordance in BMD measurement and longitudinal change in BMD between GE Lunar Prodigy and DPX. METHODS: BMD at the lumbar spine and femoral neck was measured in 135 individuals (47 men and 88 women, mean age 73+/-9 years) using both GE Lunar DPX and Prodigy densitometers at baseline. In this group, 56 individuals (22 men and 34 women) had repeated BMD measurements using the DPX and Prodigy during a subsequent follow-up visit (average duration: 2.2 years). RESULTS: For a single BMD measurement, the coefficient of concordance between the Prodigy and DPX was greater than 0.98 at the lumbar spine and 0.96 at the femoral neck, with the slope of linear regression being approximately 1.0. During the period of follow-up, the lumbar spine BMD decreased by -0.5% (S.D. 1.8%) when measured by DPX, which was significantly different (p=0.002) from the change measured by Prodigy (mean change=0, S.D. 2.0%). However, there was no significant difference (p=0.95) in the rate of change in femoral neck BMD measured by DPX (mean=-1.6%, S.D.=2.9) and Prodigy (mean=-1%, S.D.=1.8%). The correlation in rates of BMD change between Prodigy and DPX was 0.63 at the lumbar spine and 0.52 at the femoral neck. Simulation analysis showed that the theoretical maximum correlation in rates of BMD change between Prodigy and DPX was 0.71. CONCLUSIONS: Despite both densitometers being highly concordant in a single BMD measurement, discordance in the assessment of BMD changes between the Prodigy and DPX densitometers was observed. These findings have implications regarding the assessment of response to therapy in a multi-centre setting when different densitometers are used.