Dual-energy X-ray Absorptiometry Analysis Research Articles

Vertebral fracture risk in glucocorticoid-induced osteoporosis: the role of hypogonadism and corticosteroid boluses.

ObjectiveThe aim of this study was to identify the risk factors associated with fragility fracture (FF) development in glucocorticoid (GC)-treated patients.Methods127 patients (aged 62±18 years, 63% women) on GC-treatment (mean dose 14.5±14.1 mg/day and duration 47.7±69 months) were included. The clinical data collected included bone metabolism study (including gonadal axis), GC-treatment, disease activity, dual-energy X-ray absorptiometry analysis (evaluating densitometric osteoporosis (OP) and trabecular bone score (TBS) degraded microarchitecture values (DMA)), X-ray (assessing vertebral fractures (VF)), FRAX risk (GC-adjusted) and previous FF.Results17% of the patients had VF, 28% FF (VF and/or non-VF), 29% OP and 52% DMA. Patients with VF received more GC boluses (57.1% vs 29.5%, p=0.03), were older (68±13 vs 60±19 years, p=0.02), postmenopausal (100% vs 67%, p=0.02), had low testosterone levels (57% vs 11%, p=0.02), lower TBS values (1.119±0.03 vs 1.237±0.013, p<0.001) and higher FRAX risk (17.2±16 vs 9.3±7.6, p=0.003). Patients with FF showed higher accumulated GC doses (16.6±18.4 vs 11.1±12.9 g, p=0.046). On multivariate analysis, hypogonadism (OR 12.38; 95% CI 1.85 to >100, p=0.01) and having received GC boluses (OR 3.45; 95% CI 1.04 to 12.15, p=0.01) were the main factors related to VF. Hypogonadism (OR 7.03; 95% CI 1.47 to 38.37, p=0.01) and FRAX >20 (OR 7.08; 95% CI 1.28 to 53.71, p=0.02) were factors related to FF.ConclusionHypogonadism is the principal risk factor for developing fractures in GC-treated men and women, whereas receiving GC boluses is a major factor for VF. These results indicate the importance of evaluating the gonadal axis in these patients.

Changes in markers of body composition of professional male soccer players during pre-season

To evaluate changes achieved in whole-body and regional (upper limbs, lower limbs, and trunk) estimates of body composition, twenty professional male soccer players (7 defenders, 7 midfielders, 6 forwards) underwent dual-energy x-ray absorptiometry (DXA) analysis at the beginning and end of pre-season. Measures included: mass, fat mass (FM), fat-free mass (FFM), and body fat per cent (BF%). Players’ activity during on-field training sessions was monitored using Global Positioning System (GPS) units, with GPS data used to obtain estimations of energy expenditure (EE). Whole-body mass remained unchanged across the pre-season. Moderate significant increases and decreases were achieved in whole-body FFM (Pre: 59.58 ± 5.27 kg; Post: 60.61 ± 5.18 kg; p = 0.001; d = 0.87) and FM (Pre: 10.60 ± 1.88 kg; Post: 9.56 ± 1.81 kg; p = 0.001; d = 0.85), respectively. Moderate significant decreases were achieved in whole-body BF% (Pre: 14.4 ± 2.3%; Post: 12.9 ± 2.0%; p < 0.001; d = 0.94). No significant inter-positional differences were observed for the changes achieved in any global or regional estimate of body composition. Total EE was significantly correlated with ΔFM (r = 0.65, p = 0.002), ΔFFM (r = 0.46, p = 0.03), and ΔBF% (r = 0.67, p = 0.002). The total EE of pre-season training accounted for 42%, 21%, and 45% of the variance in ΔFM, ΔFFM, and ΔBF%, respectively. These findings suggest that the pre-season period is a suitable time for initiating favourable alterations in body composition following the off-season in elite soccer players.

Effects of short-term high-intensity interval and continuous exercise training on body composition and cardiac function in obese sarcopenic rats

AimWe investigated the effects of high-intensity interval and continuous short-term exercise on body composition and cardiac function after myocardial ischemia-reperfusion injury (IRI) in obese rats. MethodsRats fed with a standard chow diet (SC) or high-fat diet (HFD) for 20 weeks underwent systolic blood pressure (SBP), glycemia and dual-energy X-ray absorptiometry analyses. Then, animals fed with HFD were subdivided into three groups: sedentary (HFD-SED); moderate-intensity continuous training (HFD-MICT); and high-intensity interval training (HFD-HIIT). Exercised groups underwent four isocaloric aerobic exercise sessions, in which HFD-MICT maintained the intensity continuously and HFD-HIIT alternated it. After exercise sessions, all groups underwent global IRI and myocardial infarct size (IS) was determined histologically. Fat and muscle mass were weighted, and protein levels involved in muscle metabolism were assessed in skeletal muscle. ResultsHFD-fed versus SC-fed rats reduced lean body mass by 31% (P < 0.001), while SBP, glycemia and body fat percentage were increased by 10% (P = 0.04), 30% (P = 0.006) and 54% (P < 0.001); respectively. HFD-induced muscle atrophy was restored in exercised groups, as only HFD-SED presented lower gastrocnemius (32%; P = 0.001) and quadriceps mass (62%; P < 0.001) than SC. PGC1-α expression was 2.7-fold higher in HFD-HIIT versus HFD-SED (P = 0.04), whereas HFD-HIIT and HFD-MICT exhibited 1.7-fold increase in p-mTORSer2481 levels compared to HFD-SED (P = 0.04). Although no difference was detected among groups for IS (P = 0.30), only HFD-HIIT preserved left-ventricle developed pressure after IRI (+0.7 mmHg; P = 0.9). SignificanceShort-term exercise, continuous or HIIT, restored HFD-induced muscle atrophy and increased mTOR expression, but only HIIT maintained myocardial contractility following IRI in obese animals.

SAT-405 Trabecular Bone Score (TBS) in Primary Hyperparathyroidism (PHP): A Useful Tool?

Background: PHP is a common disorder, and regardless of being an asymptomatic entity, often leads to bone loss and osteoporosis. TBS is a software-based assessment method of trabecular bone structure of the spine based on the analysis of pixels in dual energy x-ray absorptiometry (DXA) images. The aim of this study was to evaluate TBS measurements in combination with DXA values by searching for more accurate bone fragility risk assessment among PHP patients. Methods: From June/2017 to January/2019, all patients who met the criteria for PHP diagnosis prior to surgery were selected to take part in this study. Control group was composed by non-family related healthy volunteers. Bone mineral density (BMD) by DXA (DXA; Hologic QDR 4500) at the lumbar spine, total hip, femoral neck, distal third of the non-dominant radius and TBS values by InSight were determined in 64 PHP patients and 63 controls. Total and ionized calcium, PTH, 25-hydroxyvitamin D (25(OH)D), creatinine, alkaline phosphatase, P1NP and CTX were measured in all patients and control group. Results: Primary hyperparathyroidism patients presented significant lower BMD values in all evaluated sites compared to controls. TBS measurements were also statistically different among PHP patients and controls (mean TBS PHP=1233 vs TBS controls= 1280, p=0.044). Patients and controls didn’t differ in age, sex, menopausal state or BMI (body mass index). Osteoporosis diagnosis by DXA analysis was observed in 50% of PHP patients and in 26.6% of controls. Self-reported or image-diagnosed fracture occurred in 15 PHP (23.4%) patients and in 11 (17.5%) controls. Among these fractures, vertebral fracture account for 9 (14%) in PHP group and 4 (6.3%) in controls. ROC curve analysis showed that the TBS value < 1187 is associated to significant high risk of vertebral fracture (sensibility 87.5%, specificity 67.3%) among PHP patients. Conclusion: TBS, used as a complement to DXA measurements, is a useful tool to better assess fragility risk among PHP patients.

Energy Expenditure in 21-Hydroxylase Congenital Adrenal Hyperplasia Patients and Comparison with Predictive Equations

Objective: To characterize resting energy expenditure (REE) in patients with classic 21-hydroxylase congenital adrenal hyperplasia (21-OH CAH) using indirect calorimetry and compare it to the most commonly used REE predictive equations. Methods: This case-control study comprised 29 post-pubertal 21-OH CAH patients regularly followed at the University of Campinas. Elevated serum 17-hydroxyprogesterone and CYP21 gene molecular analysis confirmed the diagnosis. A healthy control group paired by age, gender, and body mass index was examined. Dual-energy X-ray absorptiometry (DEXA) measured body compositions. A bioimpedance analyzer determined fat-free mass, and indirect calorimetry using a metabolic cart measured REE. Results: Unlike our initial hypothesis, REE was similar between the groups (18.7 ± 3.1 kcal/kg/day in CAH vs. 20.3 ± 3.5 kcal/kg/day in controls; P = .728). No predictive equations reached the stipulated accuracy criteria, thus lacking validity in REE assessment in adults with the characteristics of the group studied. DEXA analysis revealed higher body fat and diminished nonbone lean mass in 21-OH CAH. Anthropometric and bioelectrical impedance parameters were not significantly different. Conclusion: Classic 21-OH CAH is generally followed in reference centers, which may facilitate indirect calorimetry use for REE measurement. Alternatively, considering our REE findings in adult 21-OH CAH patients, nutrition management based on 25 kcal/body weight/day (measured REE × activity factor 1.2 to 1.3) may be reasonable for current body weight maintenance in these patients. Abbreviations: 17-OHP = 17-hydroxyprogesterone; 21-OH CAH = classic 21-hydroxylase deficiency congenital adrenal hyperplasia; BMI = body mass index; REE = resting energy expenditure; VO2 = volume of oxygen; VCO2 = volume of carbon dioxide.

Feasibility and reliability of DEXA analysis after total ankle arthroplasty: A cadaver study

BackgroundAlthough the outcomes of total ankle arthroplasty (TAA) have improved, unsolved problems such as stress shielding remain. Although dual energy X-ray absorptiometry (DEXA) is the “gold standard” for evaluation of these issues, it is rarely used in patients after TAA. This study aimed to establish a scan technique and to assess the mechanical changes in bone density caused by bone stock preparation. MethodsEight fresh-frozen cadaver legs were investigated by DEXA before TAA, with implant in situ, and after implant removal. Scan surface, bone mineral content, and bone mineral density were analysed to assess mechanical bone mass changes. ResultsWe examined data for density changes by bone compression after TAA, and found “good” results for internal reliability but only “acceptable” results for external reliability. ConclusionsThe results were reliable and reproducible. Using the present data, mechanical and biological processes can be considered together to understand the postoperative phases of bone remodelling after TAA.

Effect of a pulse-based diet and aerobic exercise on bone measures and body composition in women with polycystic ovary syndrome: A randomized controlled trial

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, with clinical symptoms including menstrual dysfunction and hyperandrogenemia, as well as insulin resistance which is thought to be a key contributing factor to symptoms. Insulin is also thought to positively affect bone while oligo- and amenorrhea are known to negatively affect bone. Lifestyle modification is the first recommendation to treat symptoms of PCOS; however, little is known about the effect of lifestyle interventions on bone measures in this population. Pulses (e.g., chickpeas, beans, split peas, lentils) have been shown to lower fasting insulin, and the objective of this study was to determine the effect of a pulse-based diet compared to the therapeutic lifestyle changes (TLC) diet on bone measures and body composition in women with PCOS. Women aged 18–35 years with PCOS were randomized to either a pulse-based diet or the TLC diet for 16-weeks while following an aerobic exercise program. Thirty-one in the TLC group and 29 in the pulse group completed dual-energy X-ray absorptiometry analysis following the intervention. After 16-weeks, both groups had a lower BMI, whole body fat mass, and % fat (p < 0.005), with no difference in lean mass. In both groups, lumbar spine bone mineral content (BMC) and density were higher following the intervention (p < 0.05) while femoral neck bone mineral density (BMD) was lower (p < 0.05). Intertrochanteric section modulus improved in both groups while there was a group x time interaction in femoral shaft subperiosteal width which was more favorable in the pulse group (p < 0.05). This study demonstrates that the femoral neck may be compromised during a lifestyle intervention in women with PCOS. Research is warranted to preserve bone health during lifestyle change in women with PCOS.

ANALYSIS OF DUAL-ENERGY X-RAY ABSORPTIOMETRY IMAGES USING COMPUTER VISION METHODS

PURPOSE: Dual-energy x-ray absorptiometry (DXA) is the “golden standard” for diagnosing osteoporosis. Its analyzing algorithm (software) makes it possible to distinguish the bone from the soft tissue. Until now there are only attempts to process and acquire images using automatic segmentation with convolutional neural networks (CNN). Machine reconstruction and precise specific models of anatomic structures from medical images could be accomplished using computer vision. The objective of the current work is to introduce the potential of the two computer methods and their application in the diagnostic DXA analysis. METHODS: DXA generates a report in the DICOM format which includes patient data (age, gender, height, weight, bone mineral density, T-score and Z-score) and an image of the scanned spine as well as the region of interest (ROI). The CNN methods are based mainly on intermediate analysis. The learning of the segmentation of CNN by generating segmentation labels using simple heuristic is done using computer vision. The functions of the loss and the architecture of the CNN is then determined. In that manner the right analysis of the existing medical image is made possible. RESULTS: The computer library OpenCV is the way to realize a model for the assessment of a DXA analysis. The library is available for Python programming language. The library has functions for the extraction of colour objects, image smoothing, Canny’s edge detector, Hough transform and methods for work with contours. CONCLUSIONS: The detection and extraction of images is fundamental for the analysis of DXA which is a step forward in the precision of the in-vivo diagnostic of the bone.

Vitamin E Promotes Bone Formation in a Distraction Osteogenesis Model.

The long consolidation period of distraction osteogenesis (DO) may lead to complications such as pain, infection, fracture, scar formation, malunion and delayed union. The aim of this study was to evaluate the effect of systemic Vitamin E application during mandibular DO on new bone regeneration in a rabbit model. 16 adult male 8 months old New Zealand rabbits underwent mandibular lengthening with a distractor for the study. After the latency period of 5 days, the distractor was activated at a rate of 0.5 mm/12 hours for 7 days. Experimental animals received 200 mg/kg injections of α-tocopherol intraperitoneally for 7 days starting with the operation. After the consolidation period of 30 days, rabbits were sacrificed. Lengthened mandibles were obtained and subjected to dual-energy X-ray absorptiometry (DXA), radiologic and histomorphometric analysis. Statistically, bone mineral density and bone mineral content values were found to be significantly higher in the experimental group than the control group during DXA analysis. Rabbits in the experimental group had statistically higher scores in terms of osteoblast, osteoclast, vessel numbers and newly formed bone area than the control group. Results of the present study showed that systemic Vitamin E application during DO may stimulate new bone formation in rabbits and thus results in shortened treatment time.

A Spatio-Temporal Ageing Atlas of the Proximal Femur.

Osteoporosis is an age-associated disease characterised by low bone mineral density (BMD) and micro-architectural deterioration leading to enhanced fracture risk. Conventional dual-energy X-ray absorptiometry (DXA) analysis has facilitated our understanding of BMD reduction in specific regions of interest (ROIs) within the femur, but cannot resolve spatial BMD patterns nor reflect age-related changes in bone microarchitecture due to its inherent averaging of pixel BMD values into large ROIs. To address these limitations and develop a comprehensive model of involutional bone loss, this paper presents a fully automatic pipeline to build a spatio-temporal atlas of ageing bone in the proximal femur. A new technique, termed DXA region free analysis (DXA RFA), is proposed to eliminate morphological variation between DXA scans by warping each image into a reference template. To construct the atlas, we use unprocessed DXA data from Caucasian women aged 20-97 years participating in three cohort studies in Western Europe ( ,000). A novel calibration procedure, termed quantile matching regression, is proposed to integrate data from different DXA manufacturers. Pixel-wise BMD evolution with ageing was modelled using smooth quantile curves. This technique enables characterisation of spatially-complex BMD change patterns with ageing, visualised using heat-maps. Furthermore, quantile curves plotted at different pixel coordinates showed consistently different rates of bone loss at different regions within the femoral neck. Given the close relationship between spatio-temporal bone loss and osteoporotic fracture, improved understanding of the bone ageing process could lead to enhanced prognostic, preventive and therapeutic strategies for the disease.

Dietary Non-Drug Feed Additive as an Alternative for Antibiotic Growth Promoters for Broilers During a Necrotic Enteritis Challenge.

Necrotic enteritis, caused by Clostridium perfringens, is an enteric disease that leads to poor performance and increased mortality, resulting in significant economic losses in poultry production. This study evaluated the effects of a proprietary prebiotic, probiotic, and plant extract blend on performance of broilers during coccidiosis challenge leading to necrotic enteritis (NE). In total, 744 Cobb500 male broilers were randomly allocated to 3 treatments (8 replicates, 31 birds/pen) including, the negative control (NC) fed a basal diet; the positive control (PC) fed a basal diet with Virginiamycin; and the additive group fed basal diet with a blend of prebiotic, probiotic, and plant extract (BSN). A unique, naturally occurring NE model developed to mimic field conditions was implemented to challenge the birds. This model consists of spraying a concentrated commercial coccidiosis vaccine on litter and feed upon bird placement, which, in conjunction with the presence of C. perfringens spores in the environment, leads to the development of a NE outbreak one week post vaccine application. At the onset of NE on d7, three birds/pen were selected for scoring NE lesions. Body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were recorded on days 7, 14, 28, and 42. Carcass composition was assessed by dual energy X-ray absorptiometry (DXA) analysis on day 42. Dietary supplementation of BSN significantly (p < 0.05) improved FCR during starter and grower periods. Dietary treatments had no effect on NE lesions in the small intestine. DXA analysis revealed slightly higher lean content in BSN birds compared to NC. These results showed that dietary supplementation of the BSN blend significantly improved broilers performance during the early NE challenge phase, as well as in the grower period.

Эффективность использования двухэнергетической рентгеновской абсорбциометрии и биоимпедансометрии в оценке компонентного состава тела пациентов, получающих лечение программным гемодиализом

Эффективность использования двухэнергетической рентгеновской абсорбциометрии и биоимпедансометрии в оценке компонентного состава тела пациентов, получающих лечение программным гемодиализом

Relationship of gray values in cone beam computed tomography and bone mineral density obtained by dual energy X-ray absorptiometry

The aim of this study was to assess the correlation between bone mineral density (BMD) determined with cone beam computed tomography (CBCT) gray values and BMD determined by dual energy X-ray absorptiometry (DEXA). Women age greater than 50 years requiring CBCT for implant treatment were included in the study. BMD was determined by calculating the mean gray value of CBCT cross-sectional images of anterior, premolar, retromolar, and tuberosity areas of the mandible and maxilla. Patients were then subjected to DEXA of the femoral neck and lumbar spine. Independent t tests, analysis of variance (ANOVA), Pearson's correlation tests, and receiver operating characteristic (ROC) evaluation were used for data analysis. Of 61 asymptomatic patients (mean age 64 years), 47.5% and 55.7% had abnormal BMD, based on the T-scores of the femoral neck and lumbar spine, respectively. Significant correlations were noted between the T-scores of the femoral neck and lumbar spine and the gray values of the maxillary incisor and tuberosity areas. A strong correlation exists between the CBCT gray values at different sites in the maxilla and the results of DEXA. A gray value less than 298 at the maxillary tuberosity can help distinguish patients with osteoporosis from normal individuals, with 66% to 67% accuracy and suggests the need for DEXA analysis.

MON-539 Mice Harboring a Germline Heterozygous AP2S1 Mutation, Arg15Leu, Are a Model for Familial Hypocalciuric Hypercalcemia Type 3 (FHH3)

Familial hypocalciuric hypercalcemia (FHH) is a disorder of calcium homeostasis comprising three reported genetic variants: FHH types 1 and 2 are due to germline loss-of-function mutations of the calcium-sensing receptor (CaSR) and G-protein subunit α-11 (Gα11), respectively, whereas, FHH type 3 (FHH3) is mainly caused by germline heterozygous loss-of-function mutations affecting the Arg15 residue (Arg15Cys, Arg15His or Arg15Leu) of the adaptor-related protein complex 2-sigma subunit (AP2σ), which is encoded by the AP2S1 gene, and regulates CaSR endocytosis and endosomal signaling. FHH is considered to be an asymptomatic disorder characterised by mild-to-moderate hypercalcemia, normal or mildly elevated parathyroid hormone (PTH) concentrations and low urinary calcium excretion. However, some FHH3 patients, especially those harboring the Arg15Leu AP2S1 mutation, have marked and symptomatic hypercalcemia, thereby indicating that FHH3 may represent a more severe clinical disorder. To further evaluate the impact of the Arg15Leu AP2S1 mutation on calcium homeostasis, we utilised CRISPR/Cas9-mediated gene editing to generate C57BL/6J mice harboring the germline Arg15Leu mutation. Plasma and 24-hour urine samples were collected for biochemical analysis, and bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DEXA). All studies were conducted in mice aged 12-15 weeks (n = 10-12 mice per genotype), and in accordance with institutional welfare guidelines. Wild-type (Ap2s1+/+), heterozygous (Ap2s1+/L15) and homozygous (Ap2s1L15/L15) mice were born as expected for a Mendelian pattern of inheritance, however, Ap2s1L15/L15 mice died within 48 hours of birth. In contrast, male and female Ap2s1+/L15mice were viable and biochemical analysis showed marked hypercalcemia (plasma albumin-adjusted calcium = 2.77±0.02 mmol/L) compared to wild-type (WT) mice (plasma albumin-adjusted calcium = 2.13±0.03 mmol/L, p<0.0001), and this finding was associated with significant hypophosphatemia and hypermagnesemia. Male and female Ap2s1+/L15mice also had significant elevations of plasma PTH (157±14 pmol/L) compared to WT mice (63±10 pmol/L, p<0.0001). Furthermore, urine analysis showed that Ap2s1+/L15mice were significantly hypocalciuric (fractional excretion of calcium (FECa) = 0.016±0.002) compared to WT mice (FECa =0.029±0.002, p<0.01), whilst, DEXA analysis demonstrated that Ap2s1+/L15mice have significantly reduced BMD. Thus, these studies have established a mouse model for FHH3, which highlights the importance of the AP2σ protein in the parathyroid and renal regulation of mineral and bone homeostasis. In addition, these findings demonstrate that the germline heterozygous Arg15Leu AP2S1 mutation causes a severe form of FHH characterized by marked hypercalcemia, hyperparathyroidism and reduced BMD.

Abdominal volume computed tomography assessment of body composition in dogs

BackgroundComputed tomography (CT) has been used to estimate body composition and determine tissue distribution in dogs, despite limited validation. This may introduce error into estimates of body composition studies and its effect on health in dogs. Further, the modality has not been validated against dual-energy X-ray absorptiometry (DXA) or over a wide range of dog breeds, ages and sexes. The objective of this study was to validate the use of semi-automated, abdominal volume CT for estimating total body composition of dogs relative to DXA. Twenty-two staff-owned dogs (weighing between 5.1-60 kg) were sedated and underwent full body DXA scan and abdominal CT. Abdominal tissue composition was estimated by CT using semi-automated volume segmentation, over predetermined tissue Hounsfield threshold values. Abdominal tissue composition determined by the various CT threshold ranges was compared to total body composition determined by DXA.ResultsAbdominal tissue composition estimated by CT strongly correlated with the estimates derived from DXA with a small Bland-Altman mean percentage differences in values: total body mass (− 250/2000HU: r2 = 0.985; − 1.10%); total fat mass (− 250/-25HU: r2 = 0.981; − 1.90%); total lean tissue mass (− 25/150HU: r2 = 0.972; 3.47%); and total bone mineral content (150/2000HU: r2 = 0.900; − 0.87%). Although averaged CT values compared well to DXA analysis, there was moderate variation in the individual predicted values. There was near perfect inter- and intra-observer agreement in segmentation volumes for abdominal fat.ConclusionsAbdominal volume computed tomography (CT) accurately and reliably estimates total body composition in dogs, but greater variations may be observed in dogs weighing less than 10 kg.

Dual-energy X-ray absorptiometry (DXA) and chemical composition as measures of body composition of the short-beaked echidna (Tachyglossus aculeatus aculeatus)

Dual-energy X-ray absorptiometry (DXA) is a non-invasive technology for measurement of body composition that requires validation against reference methods when applied to a new species. The aim of this work was to validate DXA for the assessment of body composition of the echidna. Body composition was determined in the short-beaked echidna (Tachyglossus aculeatus aculeatus) using a Norland XR36 DXA scanner and validated by proximate chemical analysis for dry matter, ash, crude fat (FM) and protein (as 6.25 × N) and bone mineral content (BMC). Echidnas were opportunistically obtained as ‘road kill’. Body composition data were compared between techniques by correlation and limits of agreement (LOA) analyses. Twenty-eight echidnas (11 males, 13 females, 4 not determined), weighing 520–5517 g, underwent analyses. Mean FM was 489.9 ± 439.5 g and 448.5 ± 337.5 g, lean mass was 2276.0 ± 1021.4 g and 2256.0 ± 1026.0 g, fat-free mass was 2356.3 ± 1055.1 g and 2389.5 ± 1081.1 g and BMC was 80.3 ± 39.5 g and 79.9 ± 42.4 g by DXA and chemical analysis, respectively. The two methods were highly correlated (0.84 to 0.99) and not significantly different, although LOA were large. DXA has the potential to be used to assess body composition of echidnas although further work is required to improve accuracy of measurement.

Bone Density in Children With Chronic Liver Disease Correlates With Growth and Cholestasis.

Osteopenia and bone fractures are significant causes of morbidity in children with cholestatic liver disease. Dual-energy X-ray absorptiometry (DXA) analysis was performed in children with intrahepatic cholestatic diseases who were enrolled in the Longitudinal Study of Genetic Causes of Intrahepatic Cholestasis in the Childhood Liver Disease Research Network. DXA was performed on participants aged >5 years (with native liver) diagnosed with bile acid synthetic disorder (BASD), alpha-1 antitrypsin deficiency (A1AT), chronic intrahepatic cholestasis (CIC), and Alagille syndrome (ALGS). Weight, height, and body mass index Z scores were lowest in CIC and ALGS. Total bilirubin (TB) and serum bile acids (SBA) were highest in ALGS. Bone mineral density (BMD) and bone mineral content (BMC) Z scores were significantly lower in CIC and ALGS than in BASD and A1AT (P < 0.001). After anthropometric adjustment, bone deficits persisted in CIC but were no longer noted in ALGS. In ALGS, height-adjusted and weight-adjusted subtotal BMD and BMC Z scores were negatively correlated with TB (P < 0.001) and SBA (P = 0.02). Mean height-adjusted and weight-adjusted subtotal BMC Z scores were lower in ALGS participants with a history of bone fractures. DXA measures did not correlate significantly with biliary diversion status. Conclusion: CIC patients had significant bone deficits that persisted after adjustment for height and weight and generally did not correlate with degree of cholestasis. In ALGS, low BMD and BMC reference Z scores were explained by poor growth. Anthropometrically adjusted DXA measures in ALGS correlate with markers of cholestasis and bone fracture history. Reduced bone density in this population is multifactorial and related to growth, degree of cholestasis, fracture vulnerability, and contribution of underlying genetic etiology.

Association of Genetic Variants Related to Gluteofemoral vs Abdominal Fat Distribution With Type 2 Diabetes, Coronary Disease, and Cardiovascular Risk Factors

Body fat distribution, usually measured using waist-to-hip ratio (WHR), is an important contributor to cardiometabolic disease independent of body mass index (BMI). Whether mechanisms that increase WHR via lower gluteofemoral (hip) or via higher abdominal (waist) fat distribution affect cardiometabolic risk is unknown. To identify genetic variants associated with higher WHR specifically via lower gluteofemoral or higher abdominal fat distribution and estimate their association with cardiometabolic risk. Genome-wide association studies (GWAS) for WHR combined data from the UK Biobank cohort and summary statistics from previous GWAS (data collection: 2006-2018). Specific polygenic scores for higher WHR via lower gluteofemoral or via higher abdominal fat distribution were derived using WHR-associated genetic variants showing specific association with hip or waist circumference. Associations of polygenic scores with outcomes were estimated in 3 population-based cohorts, a case-cohort study, and summary statistics from 6 GWAS (data collection: 1991-2018). More than 2.4 million common genetic variants (GWAS); polygenic scores for higher WHR (follow-up analyses). BMI-adjusted WHR and unadjusted WHR (GWAS); compartmental fat mass measured by dual-energy x-ray absorptiometry, systolic and diastolic blood pressure, low-density lipoprotein cholesterol, triglycerides, fasting glucose, fasting insulin, type 2 diabetes, and coronary disease risk (follow-up analyses). Among 452 302 UK Biobank participants of European ancestry, the mean (SD) age was 57 (8) years and the mean (SD) WHR was 0.87 (0.09). In genome-wide analyses, 202 independent genetic variants were associated with higher BMI-adjusted WHR (n = 660 648) and unadjusted WHR (n = 663 598). In dual-energy x-ray absorptiometry analyses (n = 18 330), the hip- and waist-specific polygenic scores for higher WHR were specifically associated with lower gluteofemoral and higher abdominal fat, respectively. In follow-up analyses (n = 636 607), both polygenic scores were associated with higher blood pressure and triglyceride levels and higher risk of diabetes (waist-specific score: odds ratio [OR], 1.57 [95% CI, 1.34-1.83], absolute risk increase per 1000 participant-years [ARI], 4.4 [95% CI, 2.7-6.5], P < .001; hip-specific score: OR, 2.54 [95% CI, 2.17-2.96], ARI, 12.0 [95% CI, 9.1-15.3], P < .001) and coronary disease (waist-specific score: OR, 1.60 [95% CI, 1.39-1.84], ARI, 2.3 [95% CI, 1.5-3.3], P < .001; hip-specific score: OR, 1.76 [95% CI, 1.53-2.02], ARI, 3.0 [95% CI, 2.1-4.0], P < .001), per 1-SD increase in BMI-adjusted WHR. Distinct genetic mechanisms may be linked to gluteofemoral and abdominal fat distribution that are the basis for the calculation of the WHR. These findings may improve risk assessment and treatment of diabetes and coronary disease.

Investigating a relationship between body composition and spinal curvature in farmed adult New Zealand king salmon (Oncorhynchus tshawytscha): A novel application of dual-energy X-ray absorptiometry

Characterising the pathology of skeletal anomalies in farmed finfish is key to elucidating the underlying causes. Spinal curvature is frequently observed in farmed New Zealand king salmon (Oncorhynchus tshawytscha), but its cause is currently unknown and knowledge about its pathology is limited. Dual-energy X-ray absorptiometry (DXA) was used to investigate the relationship between spinal curvature and body composition in farmed adult New Zealand king salmon. Differences in fat mass (FM), lean mass (LM) and bone mineral content (BMC) between harvest-sized fish affected and unaffected by spinal curvature were evaluated. As there is presently no evidence of an association between spinal curvature and vertebral mineral loss, between-group differences in BMC were not anticipated. Conversely, as spinal anomalies can alter the swimming and feeding of affected fish, and existing research suggests a role for soft tissues in spinal curvature development, differences in FM and LM were expected. Whole-body and regional (cranial, trunco-cranial, trunco-caudal and caudal spine) measurements of percent FM, LM and BMC were obtained from lateral DXA scans of size-matched adult female king salmon (1890–6903 g) affected (n = 31) and unaffected (n = 31) by spinal curvature. Repeatability was comparable to previous DXA studies. Measurements of FM and LM by DXA and chemical carcass analysis (CCA) were highly similar. As frequently reported in previous animal-based studies, DXA-derived BMC values were significantly lower than those obtained from CCA. Contrary to the overarching hypothesis, there were no significant between-group differences in whole-body or regional FM, LM or BMC, suggesting that there was no relationship between body composition and spinal curvature. Though the relationship between soft tissue changes and spinal curvature remains to be determined, DXA appears to be a viable tool for non-invasive assessment of king salmon body composition. However, studying end-stage disease has recognised limitations, so future investigations should utilise longitudinal designs.

Dual-energy X-ray absorptiometry scans accurately predict differing body fat content in live sheep

BackgroundThere is considerable interest in implementing mobile scanning technology for on-farm body composition analysis on live animals. These experiments evaluated the use of dual energy X-ray absorptiometry (DXA) as an accurate method of total body fat measurement in live sheep.ResultsIn Exp. 1, visceral and whole body fat analysis was undertaken in sheep with body condition scores (BCS) in the range 2 to 3.25 (scale 1: thin to 5: fat). The relationship of BCS was moderately correlated with visceral fat depot mass (r = 0.59, P < 0.01, n = 24) and whole body fat (r = 0.70, P < 0.001, n = 24). In Exp. 2, sheep with BCS in the range 2.25 to 3.75 were blood sampled to analyse circulating leptin concentrations, and were DXA scanned immediately post mortem for total body fat. Plasma leptin concentrations had low correlations with BCS (r = 0.50, P < 0.05, n = 17) and DXA body fat (r = 0.42, P < 0.05, n = 17), and no correlation with chemical body fat (r = 0.17, P > 0.05, n = 9). There was a moderate correlation between DXA body fat and BCS (r = 0.70, P < 0.01, n = 17), and DXA body fat was highly correlated with chemical body fat (r = 0.81, P < 0.001, n = 9). In Exp. 3, a series of five DXA scans, at 8-week intervals, was performed on growing sheep over a 32-week period. The average BCS ranged from 2.39 ± 0.07 (S.E.M.) to 3.05 ± 0.11 and the DXA body fat (%) ranged from 16.8 ± 0.8 to 24.2 ± 1.2. There was a moderate correlation between DXA body fat and BCS over the 32 weeks (r = 0.61, P < 0.001, n = 24).ConclusionsOverall, these experiments indicated that there was good agreement between BCS, DXA and chemical analysis for measuring total body fat in sheep, and that DXA scanning is a valid method for longitudinal measurement of total body fat in live sheep.