Precision and Accuracy of Dual‐Energy X‐ray Absorptiometry for Determining in Vivo Body Composition of Mice

Objective: To evaluate the precision and accuracy of dual‐energy X‐ray absorptiometry (DXA) for the measurement of total‐bone mineral density (TBMD), total‐body bone mineral (TBBM), fat mass (FM), and bone‐free lean tissue mass (LTM) in mice. Research Methods and Procedures: Twenty‐five male C57BL/6J mice (6 to 11 weeks old; 19 to 29 g) were anesthetized and scanned three times (with repositioning between scans) using a peripheral densitometer (Lunar PIXImus). Gravimetric and chemical extraction techniques (Soxhlet) were used as the criterion method for the determination of body composition; ash content was determined by burning at 600°C for 8 hours. Results: The mean intraindividual coefficients of variation (CV) for the repeated DXA analyses were: TBMD, 0.84%; TBBM, 1.60%; FM, 2.20%; and LTM, 0.86%. Accuracy was determined by comparing the DXA‐derived data from the first scan with the chemical carcass analysis data. DXA accurately measured bone ash content (p = 0.942), underestimated LTM (0.59 ± 0.05g, p < 0.001), and overestimated FM (2.19 ± 0.06g, p < 0.001). Thus, DXA estimated 100% of bone ash content, 97% of carcass LTM, and 209% of carcass FM. DXA‐derived values were then used to predict chemical values of FM and LTM. Chemically extracted FM was best predicted by DXA FM and DXA LTM [FM = ?0.50 + 1.09(DXA FM) ? 0.11(DXA LTM), model r² = 0.86, root mean square error (RMSE) = 0.233 g] and chemically determined LTM by DXA LTM [LTM = ?0.14 + 1.04(DXA LTM), r² = 0.99, RMSE = 0.238 g]. Discussion: These data show that the precision of DXA for measuring TBMD, TBBM, FM, and LTM in mice ranges from a low of 0.84% to a high of 2.20% (CV). DXA accurately measured bone ash content but overestimated carcass FM and underestimated LTM. However, because of the close relationship between DXA‐derived data and chemical carcass analysis for FM and LTM, prediction equations can be derived to more accurately predict body composition.     

Relationships between bone mass and micro-architecture at the mandible and iliac bone in edentulous subjects: a dual X-ray absorptiometry, computerised tomography and microcomputed tomography study

doi: 10.1111/j.1741‐2358.2011.00527.x Relationships between bone mass and micro‐architecture at the mandible and iliac bone in edentulous subjects: a dual X‐ray absorptiometry, computerised tomography and microcomputed tomography study Objectives: To compare bone volume, bone mineral density, cortical thickness and bone micro‐architecture in a series of paired mandibular and iliac bone samples analysed by various imagery techniques to see whether relationships exist between the various techniques and between mandibular and iliac bone. Materials and methods: Bone samples from the mandible and ilium were harvested in 20 cadavers and analysed by dual energy X‐ray absorptiometry (DXA), computerised tomography (CT) on a conventional hospital machine and microCT. Results: Significant correlations were found between Hounsfield density obtained by CT, and bone mass determined by microCT but not with DXA values. Cortical thickness measurements were well correlated between CT and microCT. No relationships were found between mandibular and iliac bone, when considering mineral density, cortical thickness, bone volume or micro‐architecture. Conclusion: In clinical practice, CT remains the most appropriate routine means for bone qualitative and quantitative evaluation at the mandible. In this ex vivo study, these results confirm that mandibular bone status does not reflect the axial skeletal one and assist in the placement of implants with dental prostheses in old or osteoporotic patients.     

A preliminary report on the feeding of cynomolgus monkeys (Macaca fascicularis) with a high-sugar high-fat diet for 33 weeks

Background The metabolic syndrome is common in populations exposed to a typical Western diet. There is a lack of an animal model that mimics this condition. Methods We fed 15 cynomolgus monkeys ad libitum a high‐sugar high‐fat (HSHF) diet for 33 weeks. Body weight, body composition, serum lipids, and insulin were measured at baseline and at 33 weeks. Results The animals tolerated the HSHF diet very well. In the intervention group, total serum cholesterol and low‐density lipoprotein cholesterol were 3‐ and 5‐fold higher, respectively, at 33 weeks as compared with their baseline levels. Serum high‐density lipoprotein cholesterol and triglycerides were not significantly affected. Dual‐energy X‐ray absorptiometry (DXA) analysis of the intervention group indicated that the trunk fat mass increased by 187% during this period. Conclusions Cynomolgus monkeys should be a useful model for investigating the interactions of diet and other factors such as genetics in the development of the metabolic syndrome.     

Effects of pulsed electromagnetic stimulation on patients undergoing hip revision prostheses: A randomized prospective double‐blind study

In this prospective, randomized, double‐blind study, the effect of Pulsed Electromagnetic Fields (PEMFs) was investigated in 30 subjects undergoing hip revision using the Wagner SL stem. The subjects were treated for 6 h/day up to 90 days after revision. Study end points were assessed clinically by the functional scale of Merle D'Aubigné and instrumentally by Dual‐Energy X‐ray Absorptiometry (DXA) at the Gruen zones. Subject improvement according to Merle D'Aubigné scale was higher (P < 0.05) in subjects undergoing active stimulation compared to placebo. In analyzing the DXA findings, we subtracted for each area the postoperative bone mineral density (BMD) values from those measured at 90 days and we considered all results above 3.5% as responders. There were no significant differences in the average BMD values at each Gruen zone between the two groups both postoperatively and at 90 days investigation. In Gruen zones 5 and 6, corresponding to the medial cortex, we observed six responders (40%) in both areas in the control group, while in the stimulated group we observed 14 (93%) and 10 (66%) responders, respectively (both P < 0.05). This study showed that PEMF treatment aids clinical recovery and bone stock restoration. Bioelectromagnetics 30:423–430, 2009. © 2009 Wiley‐Liss, Inc.     

Percent Body Fat and Lean Mass Explain the Gender Difference in Leptin: Analysis and Interpretation of Leptin in Hispanic and Non‐Hispanic White Adults

Objective: To reassess the relationship between body fat and fasting leptin concentrations comparing plasma vs. serum assessments of leptin; ratios vs. regression adjustment for body composition; fat and lean mass vs. percent body fat; and gender‐, ethnic‐, and age‐related variations. Research Methods and Procedures: Subjects included 766 adults from the nondiabetic cohort of the San Luis Valley Diabetes Study examined at follow up (1997 to 1998). Body composition was determined by dual energy X‐ray absorptiometry. Leptin concentrations were determined after an overnight fast. Results: Fasting serum and plasma assessments of leptin were correlated with percent body fat to the same degree. Women had significantly higher serum leptin concentrations than men when leptin concentrations were divided by body mass index, fat mass in kilograms or percent body fat. The methodological problem inherent in interpreting these ratio measures is pictorially demonstrated. In regression analysis, fat mass alone did not explain the gender difference. However, lean body mass was inversely related to leptin concentrations (p < 0.0001) and explained 71% of the gender difference at a given fat mass. Percent body fat explained all of the gender difference in leptin concentrations in both Hispanics and non‐Hispanic whites. Similar to findings about gender differences, ethnic‐ and age‐related variations in the leptin‐body fat association were minimized when percent body fat was employed as the body fat measure. Discussion: Regression analysis and percent body fat measured with dual energy X‐ray absorptiometry are recommended when assessing the relationship between leptin and body fat. Gender differences in leptin concentrations were accounted for by percent body fat in free living (no diet control), Hispanic and non‐Hispanic white adults.     

Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population

The prevalence of spondylolysis and spondylolisthesis was studied in an adult skeletal series from a rural English medieval archaeological site. Attempts were made to evaluate the association of three aspects of lumbo-sacral skeletal morphology (pelvic incidence (a measure of the anterior inclination of the sacral table), lumbar transverse process width, and the presence of lumbo-sacral spina bifida occulta) with spondylolysis and spondylolisthesis. Results indicated a high prevalence of spondylolysis compared with a modern reference population, but few cases of spondylolisthesis were identified. Analysis of prevalence with respect to age suggests that in the study population, pars interarticularis defects generally formed late in the growth period or early in adult life. The study group showed a high mean pelvic incidence compared with modern Western Europeans, indicating a more steeply inclined sacral table, which may have elevated the risk of developing pars interarticularis defects. However, no statistically valid association could be demonstrated between the presence/absence of spondylolysis and pelvic incidence in the study material. There was no evidence for a link between lumbar transverse process index or lumbo-sacral spina bifida occulta and spondylolysis/spondylolisthesis. It is concluded that the potential role of lumbo-sacral morphology, as well as of activity regimes, should be considered when interpreting spondylolysis in paleopathological studies. If the frequency of spondylolysis is to some extent an indicator of past activity regimes, it may reflect lifestyle in younger individuals rather than in mature adults. Further work investigating the link between spondylolysis and lumbo-sacral morphological variables in premodern populations would be of value.     

Paleoepidemiology,healing, and possible treatment of trauma in the medieval cemetery population of St. Helen-on-the-Walls,York, England

Traumatic lesions are commonly found in the archeological record and have potential to provide insight into the lives of past populations. This paper examines patterns of long bone fractures in the British medieval population of St. Helen-on-the-Walls from York (approximately 1100–1550) in an effort to determine patterns of healing and evidence for treatment. Long bones were macroscopically and radiologically examined. Clinical data were used to assess whether a fracture had successfully or unsuccessfully healed. The results indicate that fractures of the radius and ulna were most common. Males displayed more fractures than women. Most fractures were healed, well aligned, and without substantial deformity. Lack of evidence for deformity in bones likely to be severely affected by fracture implied that immobilization and possibly reduction was practiced on even the poorest residents of the medieval city. © 1996 Wiley-Liss, Inc.     

Radiological evaluation of bone status in the jaw and in the vertebral column in a group of women

Vertebral bone mineral content was determined in a group of 56 women, ages 30–62. These measurements were compared with the status of supporting bone in the jaws (alveolar, molar and bicuspid) and with gingival health. There was a significant decline in vertebral bone mineral content from the pre- to post-menopausal group. Molar and bicuspid measurements were highly correlated. There was some association between lumbar bone mineral content and molar bone status for postmenopausal women. For postmenopausal women, the cases of greatest percent bone loss in alveolar crest were associated with lower lumbar bone mineral content. Gingival health did not confound the bone status measurements. The 56 subjects did not exhibit the degree of reduction in bone density that is observed in the general population. Further investigation using these radiographic techniques may reveal a link between substantial bone loss in the jaw and moderate to severe bone loss in the lumbar vertebrae.     

Paleopathological and biomolecular study of tuberculosis in a medieval skeletal collection from England

Nine human skeletons of medieval date from a rural English burial site show signs of skeletal tuberculosis. They were subject to polymerase chain reaction (PCR) assays aimed at detecting traces of DNA from infecting mycobacteria, with the purpose both of confirming the paleopathological diagnosis of tuberculosis and determining in individual cases whether disease was due to M. tuberculosis or M. bovis. In all nine cases, evidence for M. tuberculosis complex DNA was found, and in all instances it appeared that disease was due to M. tuberculosis rather than M. bovis. The significance of the findings for understanding tuberculous infection in rural agrarian communities in medieval England is discussed.     

Crystal structure of a purine/pyrimidine phosphoribosyltransferase-related protein from Thermus thermophilus HB8

Adenine phosphoribosyltransferase (APRTase) is a widely distributed enzyme involved in the salvage of adenine to form an adenine nucleotide. We crystallized and determined the X-ray crystallographic structure of a purine/pyrimidine phosphoribosyltransferase-related protein from the thermophilic bacterium, Thermus thermophilus HB8. The crystal space group was C2 with unit cell dimensions of a = 167.42 A, b = 61.41 A, c = 102.39 A, beta = 94.0 degrees . Initial phases were determined to 2.6 A using the multiple wavelength anomalous dispersion method and selenomethionine substituted protein (Se-MAD), and refined using a 1.9 A "native" data set. The asymmetric unit contains two pairs of identical dimers, each related by noncrystallographic two-fold symmetry. The fifth monomer forms a similar dimer across a crystallographic two-fold axis. These dimers appear to be the biological unit with both monomers contributing to an unusual highly charged arginine-rich bridge region separating the two active sites. Comparison with distantly related APRTases reveal similarities and differences of the active site.     

Extraordinarily low bone mineral density in an old female chimpanzee (<Emphasis Type="Italic">Pan troglodytes schweinfurthii</Emphasis>) from the Mahale Mountains National Park

We examined bone mineral density (BMD) of the femoral neck and lumbar vertebrae of four chimpanzee skeletons from Mahale Mountains National Park, Tanzania, and four captive ones, with a dual energy X-ray absorptiometer. The BMD of Wansombo, an old female chimpanzee from Mahale , was remarkably lower than the mean of the other six younger adult female chimpanzees and categorized as osteoporosis. Posture, locomotion, and trunk-sacral anatomy of chimpanzees may have prevented fractures in Wansombo, whose BMD was below human osteoporosis criteria. Electronic Publication     

大鼠脊髓损伤继发骨质疏松的实验研究

目的　研究脊髓损伤后继发骨质疏松的骨组织超微结构、血液生化改变情况 ,以及损伤平面上下骨质是否均受累 ,程度是否相同。方法　实验动物为体重 30 0～ 32 0g,4～ 5月龄Wistar大鼠 110只 ,均为雄性。对照组仅行胸1 0 椎板切除不破坏硬膜 ,不损伤脊髓 ,实验组大鼠于胸1 0 椎体水平切除椎板 ,行Allen’s(6 0gcm)法损伤脊髓 ,术后两周脊髓损伤按BBB(Basso ,BeattieandBresnahan )法评分为 0分或 1分 ,观察各对照组实验组血钙、血磷、碱性磷酸酶改变情况 ,观察了肱骨外科颈、胫骨平台部以骨细胞为主的超微结构改变情况。结果与结论　大鼠骨髓损伤平面上下骨质均受累 ,但不同部位的骨骼继发骨质疏松的程度不同 ,骨质疏松后骨细胞超微结构改变显著。     

Combining information from multiple bone turnover markers as diagnostic indices for osteoporosis using support vector machines

Context: Osteoporosis (OP) is a progressive systemic bone disease. Dual-energy X-ray absorptiometry (DXA) is routinely employed and is considered the gold standard method for the diagnosis of OP.

Objective: We aimed to investigate the potential use of combined information from multiple bone turnover markers (BTMs) as a clinical diagnostic tool for OP.

Materials and methods: A total of 9053 Chinese postmenopausal women (2464 primary OP patients and 6589 healthy controls) were recruited. Serum levels of six common BTMs, including BAP, BSP, CTX, OPG, OST and sRANKL were assayed. Models based on support vector machine (SVM) were constructed to explore the efficiency of different combinations of multiple BTMs for OP diagnosis.

Results: Increasing the number of BTMs used in generating the models increased the predictive power of the SVM models for determining the disease status of study subjects. The highest kappa coefficient for the model with one BTM (BAP) compared to DXA was 0.7783. The full model incorporating all six BTMs resulted in a high kappa coefficient of 0.9786.

Conclusion: Our findings showed that although single BTMs were not sufficient for OP diagnosis, appropriate combinations of multiple BTMs incorporated into the SVM models showed almost perfect agreement with the DXA.     

Technical note: A stereological analysis of the cross‐sectional variability of the femoral osteon population

Unbiased selection of regions of interest (ROIs) and unbiased definition of histological structures are needed to improve the repeatability of microscopic methods for age at death determination and to reduce operator subjectivity. We present results obtained by selecting ROIs according to stereological principles on a sample of 28 femoral cross sections of Caucasoid males aged 20–89 years. A regular grid was overlaid on the cross section, and the ROIs were selected as close as possible to the periosteum in the anterior, lateral, and medial regions. The areas consisting of all intact secondary osteons plus fragments were outlined and osteon population density, percent osteon population, area, and perimeter were calculated using stereological methods and software. Overall, the analyses of intra‐ and inter‐section variability showed no significant difference between the ROIs, i.e., the location within the cross section of the ROIs does not affect the outcome of the analyses. The individual variability was found to be higher in adults aged 30–55 years than in other age ranges. ranges. Am J Phys Anthropol 2010. © 2010 Wiley‐Liss, Inc.     

Age-related cortical bone loss in women from a 3rd-4th century AD population from England

Age-dependent cortical bone loss in adult females from a skeletal assemblage from 3rd-4th century AD England was studied using metacarpal radiogrammetry. Results showed reduced peak cortical bone thickness compared with modern subjects, and the magnitude of cortical bone loss in older females compared with their younger counterparts was greater than that documented for a modern reference population. An elevated prevalence of fractures classically associated with osteoporosis was also observed in the over-50-year cohort. The severity of osteoporosis in this group is difficult to explain in terms of extraneous factors relating to 3rd-4th century lifestyles. Given the important genetic component in osteoporosis, the results may indicate some inherent susceptibility in this particular population to the disease, and ways in which this possibility might be further explored are suggested.     

Skeletal growth in a medieval population from Sudanese Nubia

Long bone growth is analyzed for 180 children from a Medieval population at Kulubnarti in Sudanese Nubia (550–1450 A.D.). A regional interpopulation comparison is made with growth data from Wadi Halfa in Lower Nubia, and an intrapopulation analysis is undertaken to assess diachronic changes in growth at Kulubnarti. Changes in growth patterns are interpreted in the context of mortality and morbidity profiles and relationships between the three variables are discussed. It is suggested that changes in the sociopolitical environment may have been responsible in part for altering levels of biological stress and impacting growth.