Skeletal effects of sleeve gastrectomy, by sex and menopausal status and compared to Roux-en-Y gastric bypass surgery.

Context: Roux-en-Y gastric bypass (RYGB) has deleterious effects on bone mass, microarchitecture, and strength. The skeletal effects of sleeve gastrectomy (SG), now the most commonly performed bariatric surgical procedure, are incompletely understood.

Objective: We examined changes in bone turnover, areal and volumetric bone mineral density (aBMD, vBMD), and appendicular bone microarchitecture and estimated strength after SG.

Male-female spatio-temporal differences of age-related bone changes show faster bone deterioration in older women at femoral regions associated with incident hip fracture.

A better understanding of how age-related bone loss affects the fracture-prone regions of the proximal femur could lead to more informed fracture-prevention strategies. Therefore, the aim of this work was to assess the spatio-temporal distribution of bone deterioration in older men and women with aging. A subset of 305 men (74.

Skeletal effects of sleeve gastrectomy, by sex and menopausal status and in comparison to Roux-en-Y gastric bypass surgery.

Context: Roux-en-Y gastric bypass (RYGB) has deleterious effects on bone mass, microarchitecture, and strength. Data are lacking on the skeletal effects of sleeve gastrectomy (SG), now the most commonly performed bariatric surgical procedure.

Objective: We examined changes in bone turnover, areal and volumetric bone mineral density (aBMD, vBMD), and appendicular bone microarchitecture and estimated strength after SG.

A new hip fracture risk index derived from FEA-computed proximal femur fracture loads and energies-to-failure.

Unlabelled: Hip fracture risk assessment is an important but challenging task. Quantitative CT-based patient-specific finite element (FE) analysis (FEA) incorporates bone geometry and bone density in the proximal femur. We developed a global FEA-computed fracture risk index to increase the prediction accuracy of hip fracture incidence.

Vaccines for COVID-19: An Overview.

The advent of the COVID-19 pandemic in the final months of 2019 prompted an extraordinary response on the part of the scientific community, with fundamental research on the biology of the virus and the human immune response, and development of testing, therapeutics, and vaccines occurring on an unprecedentedly short timescale. Within a year after the worldwide outbreak of the disease, more than 40 vaccine candidates had emerged, with 21 candidates in phase 3 trials or already being used on an emergency basis. Many of these vaccines have involved innovative platforms.

Heterogeneous Spatial and Strength Adaptation of the Proximal Femur to Physical Activity: A Within-Subject Controlled Cross-Sectional Study.

Physical activity (PA) enhances proximal femur bone mass, as assessed using projectional imaging techniques. However, these techniques average data over large volumes, obscuring spatially heterogeneous adaptations. The current study used quantitative computed tomography, statistical parameter mapping, and subject-specific finite element (FE) modeling to explore spatial adaptation of the proximal femur to PA.

Greater Bone Marrow Adiposity Predicts Bone Loss in Older Women.

Bone marrow adiposity (BMA) is associated with aging and osteoporosis, but whether BMA can predict bone loss and fractures remains unknown. Using data from the Age Gene/Environment Susceptibility (AGES)-Reykjavik study, we investigated the associations between H-MRS-based measures of vertebral bone marrow adipose tissue (BMAT), annualized change in bone density/strength by quantitative computed tomography (QCT) and DXA, and secondarily, with incident clinical fractures and radiographic vertebral fractures among older adults. The associations between BMAT and annualized change in bone density/strength were evaluated using linear regression models, adjusted for age, body mass index (BMI), diabetes, estradiol, and testosterone.

Use of Quantitative Computed Tomography to Assess for Clinically-relevant Skeletal Effects of Prolonged Spaceflight on Astronaut Hips.

Introduction: In 2010, experts in osteoporosis and bone densitometry were convened by the Space Life Sciences Directorate at NASA Johnson Space Center to identify a skeletal outcome in astronauts after spaceflight that would require a clinical response to address fracture risk. After reviewing astronaut data, experts expressed concern over discordant patterns in loss and recovery of bone mineral density (BMD) after spaceflight as monitored by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). The pilot study described herein demonstrates the use of QCT to evaluate absence of recovery in hip trabecular BMD by QCT as an indicator of a clinically actionable response.

Hip Fracture Discrimination Based on Statistical Multi-parametric Modeling (SMPM).

Studies using quantitative computed tomography (QCT) and data-driven image analysis techniques have shown that trabecular and cortical volumetric bone mineral density (vBMD) can improve the hip fracture prediction of dual-energy X-ray absorptiometry areal BMD (aBMD). Here, we hypothesize that (1) QCT imaging features of shape, density and structure derived from data-driven image analysis techniques can improve the hip fracture discrimination of classification models based on mean femoral neck aBMD (Neck.aBMD), and (2) that data-driven cortical bone thickness (Ct.

Cigarette Smoking Is Associated With Lower Quadriceps Cross-sectional Area and Attenuation in Older Adults.

Introduction: In addition to well-established links with cardiovascular and respiratory diseases, cigarette smoking may affect skeletal muscle; however, associations with quadriceps atrophy, density, and function are unknown. This study explored the associations of current and former smoking with quadriceps muscle area and attenuation as well as muscle force (assessed as knee extension peak torque) and rate of torque development-a measure of muscle power in older adults.

Methods: Data from 4469 older adults, aged 66-95 years at baseline in the Age, Gene/Environment Susceptibility-Reykjavik Study with measurements of thigh computed tomography, isometric knee extension testing, self-reported smoking history, and potential covariates were analyzed.

Hip load capacity cut-points for Astronaut Skeletal Health NASA Finite Element Strength Task Group Recommendations.

Concerns raised at a 2010 Bone Summit held for National Aeronautics and Space Administration Johnson Space Center led experts in finite element (FE) modeling for hip fracture prediction to propose including hip load capacity in the standards for astronaut skeletal health. The current standards for bone are based upon areal bone mineral density (aBMD) measurements by dual X-ray absorptiometry (DXA) and an adaptation of aBMD cut-points for fragility fractures. Task Group members recommended (i) a minimum permissible outcome limit (POL) for post-mission hip bone load capacity, (ii) use of FE hip load capacity to further screen applicants to astronaut corps, (iii) a minimum pre-flight standard for a second long-duration mission, and (iv) a method for assessing which post-mission physical activities might increase an astronaut's risk for fracture after return.

Chronic Kidney Disease Is Associated With Greater Bone Marrow Adiposity.

Bone marrow adiposity is associated with aging, osteoporosis, and reduced hematopoiesis, as well as anorexia nervosa, but little is known about the underlying mechanisms that affect marrow adiposity. Chronic kidney disease (CKD) may influence bone marrow adipose tissue (BMAT), possibly through loss of lean mass or higher circulating levels of sclerostin. To test these hypotheses, we investigated the cross-sectional association between estimated glomerular filtration rate (eGFR) as a measure of kidney function and H-MRS-based measurement of vertebral BMAT (L1 to L4) in 475 older adults from the Age Gene/Environment Susceptibility (AGES)-Reykjavik study.

Sex hormones are negatively associated with vertebral bone marrow fat.

Context: Higher bone marrow fat (BMF) is associated with osteoporosis and reduced hematopoiesis. Exogenous estradiol reduces BMF in older women, but effects of endogenous sex hormones are unknown.

Objective: To determine if endogenous sex hormones are associated with BMF in older men and women.

Osteocyte-Intrinsic TGF-β Signaling Regulates Bone Quality through Perilacunar/Canalicular Remodeling.

Poor bone quality contributes to bone fragility in diabetes, aging, and osteogenesis imperfecta. However, the mechanisms controlling bone quality are not well understood, contributing to the current lack of strategies to diagnose or treat bone quality deficits. Transforming growth factor beta (TGF-β) signaling is a crucial mechanism known to regulate the material quality of bone, but its cellular target in this regulation is unknown.

Spatial Differences in the Distribution of Bone Between Femoral Neck and Trochanteric Fractures.

There is little knowledge about the spatial distribution differences in volumetric bone mineral density and cortical bone structure at the proximal femur between femoral neck fractures and trochanteric fractures. In this case-control study, a total of 93 women with fragility hip fractures, 72 with femoral neck fractures (mean ± SD age: 70.6 ± 12.

C-L-methyl methionine dynamic PET/CT of skeletal muscle: response to protein supplementation compared to L-[ring C] phenylalanine infusion with serial muscle biopsy.

Objective: The objective of this study was to determine if clinical dynamic PET/CT imaging with C-L-methyl-methionine (C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring C] phenylalanine (C-Phe).

Methods: Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with C-MET and a stable isotope infusion of C-Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient K from analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle.

Muscle Quality and Myosteatosis: Novel Associations With Mortality Risk: The Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study.

Muscle composition may affect mortality risk, but prior studies have been limited to specific samples or less precise determination of muscle composition. We evaluated associations of thigh muscle composition, determined using computed tomography imaging, and knee extension strength with mortality risk among 4,824 participants aged 76.4 (standard deviation (SD), 5.

Automatic multi-parametric quantification of the proximal femur with quantitative computed tomography.

Background: Quantitative computed tomography (QCT) imaging is the basis for multiple assessments of bone quality in the proximal femur, including volumetric bone mineral density (vBMD), tissue volume, estimation of bone strength using finite element modeling (FEM), cortical bone thickness, and computational-anatomy-based morphometry assessments.

Methods: Here, we present an automatic framework to perform a multi-parametric QCT quantification of the proximal femur. In this framework, the proximal femur is cropped from the bilateral hip scans, segmented using a multi-atlas based segmentation approach, and then assigned volumes of interest through the registration of a proximal femoral template.

Plasma phospholipid fatty acids and fish-oil consumption in relation to osteoporotic fracture risk in older adults: the Age, Gene/Environment Susceptibility Study.

Background: Polyunsaturated fatty acids (PUFAs) may play a role in fracture, but studies have been largely confined to estimates of dietary intake.

Objective: We aimed to examine associations between fatty acids measured in late life and fish-oil consumption in early life, midlife, and late life with osteoporotic fracture risk.

Design: Osteoporotic fractures were determined from medical records over 5-9 y of follow-up in men and women aged 66-96 y.

Fat distribution and mortality: the AGES-Reykjavik Study.

Objective: This study examined associations of regional fat depots with all-cause mortality over 11 years of follow-up.

Methods: Data were from 2,187 men and 2,900 women, aged 66-96 years in the AGES-Reykjavik Study. Abdominal visceral fat and subcutaneous fat and thigh intermuscular fat and subcutaneous fat were measured by CT.

Circulating sclerostin associated with vertebral bone marrow fat in older men but not women.

Context: Osteocyte activity is crucial to the maintenance of bone quality. Sclerostin, an osteocyte product, inhibits bone formation, yet higher circulating sclerostin is associated with higher bone density. Bone marrow fat (MF) is associated with osteoporosis, but little is known about the relationship between osteocyte activity and MF.

Inter-scanner differences in in vivo QCT measurements of the density and strength of the proximal femur remain after correction with anthropomorphic standardization phantoms.

In multicenter studies and longitudinal studies that use two or more different quantitative computed tomography (QCT) imaging systems, anthropomorphic standardization phantoms (ASPs) are used to correct inter-scanner differences and allow pooling of data. In this study, in vivo imaging of 20 women on two imaging systems was used to evaluate inter-scanner differences in hip integral BMD (iBMD), trabecular BMD (tBMD), cortical BMD (cBMD), femoral neck yield moment (My) and yield force (Fy), and finite-element derived strength of the femur under stance (FEstance) and fall (FEfall) loading. Six different ASPs were used to derive inter-scanner correction equations.

Axial QCT: clinical applications and new developments.

Quantitative computed tomography (QCT) is currently undergoing a renaissance, with an increasing number of studies being published and the definition of both QCT-specific osteoporosis thresholds and treatment criteria. Compared with dual-energy X-ray absorptiometry, the current standard bone mineral density technique, QCT has a number of pertinent advantages, including volumetric measurements, less susceptibility to degenerative spine changes, and higher sensitivity to changes in bone mass. Disadvantages include the higher radiation doses and less experience with fracture prediction and therapy monitoring.

The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants: a phantom study.

Background: To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of (18)F-fluorodeoxyglucose uptake in lesions near metallic prostheses.

Methods: A custom hip prosthesis phantom with a lesion-sized cavity filled with 0.2 ml (18)F-FDG solution having an activity of 3.