Trabecular Bone Volume Fraction Research Articles

Blocking CCN2 Reduces Established Bone Loss Induced by Prolonged Intense Loading by Increasing Osteoblast Activity in Rats.

We have an operant model of reaching and grasping in which detrimental bone remodeling is observed rather than beneficial adaptation when rats perform a high-repetition, high-force (HRHF) task long term. Here, adult female Sprague-Dawley rats performed an intense HRHF task for 18 weeks, which we have shown induces radial trabecular bone osteopenia. One cohort was euthanized at this point (to assay the bone changes post task; HRHF-Untreated). Two other cohorts were placed on 6 weeks of rest while being simultaneously treated with either an anti-CCN2 (FG-3019, 40 mg/kg body weight, ip; twice per week; HRHF-Rest/anti-CCN2), or a control IgG (HRHF-Rest/IgG), with the purpose of determining which might improve the trabecular bone decline. Results were compared with food-restricted control rats (FRC). MicroCT analysis of distal metaphysis of radii showed decreased trabecular bone volume fraction (BV/TV) and thickness in HRHF-Untreated rats compared with FRCs; responses improved with HRHF-Rest/anti-CCN2. Rest/IgG also improved trabecular thickness but not BV/TV. Histomorphometry showed that rest with either treatment improved osteoid volume and task-induced increases in osteoclasts. Only the HRHF-Rest/anti-CCN2 treatment improved osteoblast numbers, osteoid width, mineralization, and bone formation rate compared with HRHF-Untreated rats (as well as the latter three attributes compared with HRHF-Rest/IgG rats). Serum ELISA results were in support, showing increased osteocalcin and decreased CTX-1 in HRHF-Rest/anti-CCN2 rats compared with both HRHF-Untreated and HRHF-Rest/IgG rats. These results are highly encouraging for use of anti-CCN2 for therapeutic treatment of bone loss, such as that induced by chronic overuse. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Associations of body mass index, body fat percentage and sarcopenia components with bone health estimated by second-generation high-resolution peripheral quantitative computed tomography in older adults with obesity

PurposeTo investigate associations between body mass index (BMI), body fat percentage, and components of sarcopenia (muscle mass and muscle strength/power), with bone microarchitecture measured by high-resolution peripheral computed tomography (HR-pQCT) in older adults with obesity. MethodsSeventy-four adults aged ≥ 55 years with body fat percentage ≥ 30 % (men) or ≥40 % (women) were included. Fat mass, lean mass and total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD) were measured by dual-energy X-ray absorptiometry. Appendicular lean mass (ALM) was calculated as the sum of lean mass in the upper- and lower-limbs. BMI was calculated and participants completed physical function assessments including stair climb power test. Distal tibial bone microarchitecture was assessed using HR-pQCT. Linear regression (β-coefficients and 95 % confidence intervals) analyses were performed with adjustment for confounders including age, sex, smoking status, vitamin D and self-reported moderate to vigorous physical activity. ResultsBMI and ALM/height2 were both positively associated with total hip, femoral neck and lumbar spine aBMD and trabecular bone volume fraction after adjusting for confounders (all p < 0.05). Body fat percentage was not associated with aBMD or any trabecular bone parameters but was negatively associated with cortical area (p < 0.05). Stair climb power (indicating better performance) was positively associated with cortical area and negatively associated with bone failure load (both p < 0.05). ConclusionHigher BMI, ALM/height2 and muscle power were associated with more favourable bone microarchitecture, but higher body fat percentage was negatively associated with cortical bone area. These findings suggest that high BMI may be protective for fractures and that this might be attributable to higher muscle mass and/or forces, while higher relative body fat is not associated with better bone health in older adults with obesity.

MiR-210 improves postmenopausal osteoporosis in ovariectomized rats through activating VEGF/Notch signaling pathway

BackgroundTo explore the effect and mechanism of action of miR-210 on postmenopausal osteoporosis (PMPO) in ovariectomized rats in vivo.MethodsAn ovariectomized (OVX) rat model was established by ovariectomy. Tail vein injection was performed to overexpress and knock down miR-210 in OVX rats, followed by the collection of blood and femoral tissues from each group of rats. And quantitative real-time polymerase chain reaction (qRT-PCR) was applied to assess the expression level of miR-210 in femoral tissues of each group. Micro computed tomography (Micro CT) was adopted to scan the microstructure of the femoral trabecula in each group to obtain relevant data like bone mineral density (BMD), bone mineral content (BMC), trabecular bone volume fraction (BV/TV), trabecular thickness (Tb.Th), bone surface-to-volume ratio (BS/BV), and trabecular separation (Tb.Sp). ELISA was used for determining the level of bone alkaline phosphatase (BALP), amino-terminal propeptide of type I procollagen (PINP), osteocalcin (OCN), and C-terminal telopeptide of type I collagen (CTX-1) in serum; and Western blot for the protein level of Runt-related transcription factor 2 (Runx2), osteopontin (OPN), and collagen type I alpha 1 (COL1A1) in femoral tissues.ResultsMiR-210 expression was significantly decreased in femoral tissues of OVX rats. Overexpression of miR-210 could obviously increase BMD, BMC, BV/TV and Tb.Th, whereas significantly decrease BS/BV and Tb.Sp in femurs of OVX rats. Moreover, miR-210 also downregulated BALP and CTX-1 level, upregulated PINP and OCN level in the serum of OVX rats promoted the expression of osteogenesis-related markers (Runx2, OPN and COL1A1) in the femur of OVX rats. Additionally, further pathway analysis revealed that high expression of miR-210 activated the vascular endothelial growth factor (VEGF)/Notch1 signaling pathway in the femur of OVX rats.ConclusionHigh expression of miR-210 may improve the micromorphology of bone tissue and modulate bone formation and resorption in OVX rats by activating the VEGF/Notch1 signaling pathway, thereby alleviating osteoporosis. Consequently, miR-210 can serve as a biomarker for the diagnosis and treatment of osteoporosis in postmenopausal rats.

Male Runners With Lower Energy Availability Have Impaired Skeletal Integrity Compared to Nonathletes.

Female athletes, particularly runners, with insufficient caloric intake for their energy expenditure [low energy availability (EA) or relative energy deficiency] are at risk for impaired skeletal integrity. Data are lacking in male runners. To determine whether male runners at risk for energy deficit have impaired bone mineral density (BMD), microarchitecture, and estimated strength. Cross-sectional. Clinical research center. 39 men (20 runners, 19 controls), ages 16-30 years. Areal BMD (dual-energy x-ray absorptiometry); tibia and radius volumetric BMD and microarchitecture (high-resolution peripheral quantitative computed tomography); failure load (microfinite element analysis); serum testosterone, estradiol, leptin; energy availability. Mean age (24.5 ± 3.8 y), lean mass, testosterone, and estradiol levels were similar; body mass index, percent fat mass, leptin, and lumbar spine BMD Z-score (-1.4 ± 0.8 vs -0.8 ± 0.8) lower (P < .05); and calcium intake and running mileage higher (P ≤ .01) in runners vs controls. Runners with EA <median had lower lumbar spine (-1.5 ± 0.7, P = .028), while runners with EA ≥median had higher hip (0.3 ± 0.7 vs -0.4 ± 0.5, P = .002), BMD Z-scores vs controls. After adjusting for calcium intake and running mileage, runners with EA <median had lower mean tibial total and trabecular volumetric BMD, trabecular bone volume fraction, cortical porosity, and apparent modulus vs controls (P < .05). Appendicular lean mass and serum estradiol (R ≥ 0.45, P ≤ .046), but not testosterone, were positively associated with tibial failure load among runners. Despite weight-bearing activity, skeletal integrity is impaired in male runners with lower caloric intake relative to exercise energy expenditure, which may increase bone stress injury risk. Lower estradiol and lean mass are associated with lower tibial strength in runners.

Abstract 365: Targeting FGF21 inhibits tumor growth and attenuates cachexia in experimental colorectal cancer

Abstract Background: Colorectal cancer (CRC) is frequently accompanied by cachexia, an uncured multi-organ wasting syndrome, debilitating musculoskeletal health, physical function, and overall survival. Fibroblast growth factor 21 (FGF21) is a modulator of musculoskeletal health and metabolism and has been associated with CRC risk and progression. Here, we investigated the effects of tumor derived FGF21 on musculoskeletal health in CRC. Methods: Plasma from CRC patients and preclinical models of CRC (C26, MC38) were assessed for circulating FGF21 levels, and CRC cell lines (C26, MC38, HCT116) were screened for FGF21 expression. Using CRISPR/Cas9 technology, FGF21 was deleted from MC38 cells (KO-MC38). 8-week-old male C57BL/6J mice were subcutaneously injected (1.0x106) with wild-type (WT-MC38) or FGF21-/- (KO-MC38) MC38 tumor cells, while experimental control animals received saline (n = 10-13/group). Animals underwent electrophysiological testing to obtain motor unit number estimation (MUNE) 48 hours prior to euthanasia and were assessed for maximum plantarflexion torque 24 hours prior to euthanasia. At the time of euthanasia, plasma was collected for assessment of systemic FGF21, while tumors and skeletal muscles (gastrocnemius, quadriceps, and tibialis anterior) were excised and weighed. Femur bones were processed for microcomputed tomography (µCT) imaging and analysis. Results: CRC patients and MC38 tumor hosts demonstrated elevated circulating plasma FGF21 (p&amp;lt;0.05) compared to controls. Gene expression of CRC cells revealed an 11-fold increase of FGF21 in MC38 compared to C26 and HCT116 cells. WT-MC38 tumor hosts had elevated plasma FGF21 (4-fold; p&amp;lt;0.05) compared to control, which was unchanged in KO-MC38 hosts. In line with the development of cachexia, WT-MC38 hosts displayed reductions in muscle mass (gastrocnemius: -5%; p&amp;lt;0.05, quadriceps: -10%; p&amp;lt;0.01, tibialis anterior: -8%; p&amp;lt;0.01), MUNE (-31%; p&amp;lt;0.01), and plantarflexion torque (-10%; p&amp;lt;0.05). Meanwhile, µCT of femur bones demonstrated reductions in trabecular bone volume fraction (BV/TV: -30%; p&amp;lt;0.05) and cortical cross-sectional thickness (Cs.Th: -14%; p&amp;lt;0.05) in WT-MC38 hosts compared to experimental controls. Conversely, when compared to WT-MC38, KO-MC38 hosts had preserved skeletal muscle mass (gastrocnemius: +7%; p&amp;lt;0.01, quadriceps: +13%; p&amp;lt;0.001, tibialis anterior: +8%; p&amp;lt;0.001), MUNE (+47%; p&amp;lt;0.01), plantarflexion torque (+8%; p&amp;lt;0.05), and bone mass (BV/TV: +69%; p&amp;lt;0.001, Cs.Th: +23%; p&amp;lt;0.001). Strikingly, the mass of KO-MC38 tumors was reduced 75% (p&amp;lt;0.01) compared to WT-MC38 tumors. Conclusion: Our data suggest that targeting CRC-derived FGF21 halts tumor growth, resulting in preservation of musculoskeletal health and function. Thus, counteracting tumor-derived FGF21 may serve as a therapeutic intervention against the progression of cancer and cancer-associated cachexia. Citation Format: Fabrizio Pin, Anika Shimonty, Joshua Robert Huot. Targeting FGF21 inhibits tumor growth and attenuates cachexia in experimental colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 365.

Abstract 3490: IGFBP1 mediates musculoskeletal defects in colorectal cancer

Abstract Colorectal cancer (CRC) is frequently accompanied by cachexia, an uncured multi-systemic wasting syndrome that affects the majority of patients, especially when the disease recurs with liver metastases (LMs). Muscle and bone loss are amongst the most detrimental symptoms of cachexia and directly cause increased morbidity and mortality. We and others have shown that CRC also promotes metabolic and genomic perturbations of the liver, and further, that formation of LMs exacerbates muscle and bone wasting. These observations, along with evidence that liver-derived factors (i.e., hepatokines) may poorly influence musculoskeletal health, suggest an endocrine role of the liver in mediating cancer-induced cachexia. In the present study, we identified the hepatokine insulin-like growth factor binding protein 1 (IGFBP1) as a novel mediator of musculoskeletal wasting in CRC. Plasma from CRC patients and preclinical mouse models of CRC (C26, MC38, HCT116, ApcMin/+) were assessed for circulating IGFBP1 levels. AML12 hepatocytes were cultured with CRC cells (C26, MC38, HCT116) to assess tumor induced hepatic IGFBP1 production, while C2C12 myotubes and osteoclast precursor cells were cultured to examine the in vitro effects of IGFBP1 on myotube atrophy and osteoclastogenesis. 8-week-old male wild-type (WT) C57BL/6J and IGFBP1-KO mice were intrasplenically injected with MC38 tumor cells (mMC38) to mimic hepatic dissemination of cancer cells, while sham-operated animals received saline. Animals were assessed for muscle force 24-hours prior to euthanasia, and skeletal muscles and bone were collected for molecular and morphological analyses. CRC patients and CRC tumor-bearing mice demonstrated markedly elevated circulating plasma IGFBP1, also supported by increased liver IGFBP1 mRNA expression in C26, MC38 and HCT116 hosts. Follow-up in vitro studies demonstrated that co-culturing CRC cells (lacking IGFBP1 expression) with AML12 hepatocytes promotes IGFBP1 production, thereby suggesting that IGFBP1 is purely host-derived. Further, treatment with recombinant IGFBP1 was sufficient to stimulate osteoclastogenesis, while also promoting atrophy of C2C12 myotubes. Conversely, use of anti-IGFBP1 neutralizing antibodies prevented osteoclastogenesis and preserved C2C12 myotube size when exposed to plasma from mice bearing CRCs. Notably, WT mMC38 bearers displayed reductions in muscle mass and strength, as well as in trabecular bone volume fraction (BV/TV) and trabecular number (Tb.N). Conversely, IGFBP1-KO tumor hosts exhibited preserved skeletal muscle and bone mass. Altogether, our data implicate IGFBP1, an exquisitely liver-derived factor, as a novel mediator of musculoskeletal deficits in CRC cachexia, and supports novel strategies to counteract host-derived factors in the treatment of cancer-associated multi-organ complications. Citation Format: Joshua R. Huot, Fabrizio Pin, Andrea Bonetto. IGFBP1 mediates musculoskeletal defects in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3490.

Androgen therapy does not prevent bone loss and arterial calcifications in male rats with chronic kidney disease.

Patients suffering from chronic kidney disease (CKD) often experience bone loss and arterial calcifications. It is unclear if hypogonadism contributes to the development of these complications and whether androgen therapy might prevent them. Male adult rats were randomized into four groups. The first group received standard chow (control), while three other groups were fed a 0.25% adenine/low vitamin K diet (CKD). Two CKD groups were treated with testosterone or dihydrotestosterone (DHT), whereas the control group and one CKD group received vehicle (VEH). CKD animals had 10-fold higher serum creatinine and more than 15-fold higher parathyroid hormone levels compared to controls. Serum testosterone levels were more than two-fold lower in the CKDVEH group compared to control + VEH and CKD + testosterone groups. Seminal vesicle weight was reduced by 50% in CKDVEH animals and restored by testosterone and DHT. CKD animals showed a low bone mass phenotype with decreased trabecular bone volume fraction and increased cortical porosity, which was not rescued by androgen treatment. Aortic calcification was much more prominent in CKD animals and not unequivocally prevented by androgens. Messenger RNA expression of the androgen receptor-responsive genes Acta1 and Col1a1 was reduced by CKD and stimulated by androgen treatment in levator ani muscle but not in the bone or aortic tissue. We conclude that adenine-induced CKD results in the development of hypogonadism in male rats. Androgen therapy is effective in restoring serum testosterone levels and androgen-sensitive organ weights but does not prevent bone loss or arterial calcifications, at least not in the presence of severe hyperparathyroidism.

Trabecular bone remodeling in the aging mouse: A micro-multiphysics agent-based in silico model using single-cell mechanomics.

Bone remodeling is regulated by the interaction between different cells and tissues across many spatial and temporal scales. Notably, in silico models are regarded as powerful tools to further understand the signaling pathways that regulate this intricate spatial cellular interplay. To this end, we have established a 3D multiscale micro-multiphysics agent-based (micro-MPA) in silico model of trabecular bone remodeling using longitudinal in vivo data from the sixth caudal vertebra (CV6) of PolgA(D257A/D257A) mice, a mouse model of premature aging. Our in silico model includes a variety of cells as single agents and receptor-ligand kinetics, mechanomics, diffusion and decay of cytokines which regulate the cells' behavior. We highlighted its capabilities by simulating trabecular bone remodeling in the CV6 of five mice over 4weeks and we evaluated the static and dynamic morphometry of the trabecular bone microarchitecture. Based on the progression of the average trabecular bone volume fraction (BV/TV), we identified a configuration of the model parameters to simulate homeostatic trabecular bone remodeling, here named basal. Crucially, we also produced anabolic, anti-anabolic, catabolic and anti-catabolic responses with an increase or decrease by one standard deviation in the levels of osteoprotegerin (OPG), receptor activator of nuclear factor kB ligand (RANKL), and sclerostin (Scl) produced by the osteocytes. Our results showed that changes in the levels of OPG and RANKL were positively and negatively correlated with the BV/TV values after 4weeks in comparison to basal levels, respectively. Conversely, changes in Scl levels produced small fluctuations in BV/TV in comparison to the basal state. From these results, Scl was deemed to be the main driver of equilibrium while RANKL and OPG were shown to be involved in changes in bone volume fraction with potential relevance for age-related bone features. Ultimately, this micro-MPA model provides valuable insights into how cells respond to their local mechanical environment and can help to identify critical pathways affected by degenerative conditions and ageing.

C3a-C3aR signaling is a novel modulator of skeletal homeostasis

Osteoimmune studies have identified complement signaling as an important regulator of the skeleton. Specifically, complement anaphylatoxin receptors (i.e., C3aR, C5aR) are expressed on osteoblasts and osteoclasts, implying that C3a and/or C5a may be candidate mediators of skeletal homeostasis. The study aimed to determine how complement signaling influences bone modeling/remodeling in the young skeleton. Female C57BL/6J C3aR−/-C5aR−/− vs. wildtype and C3aR−/− vs. wildtype mice were examined at age 10 weeks. Trabecular and cortical bone parameters were analyzed by micro-CT. In situ osteoblast and osteoclast outcomes were determined by histomorphometry. Osteoblast and osteoclast precursors were assessed in vitro. C3aR−/-C5aR−/− mice displayed an increased trabecular bone phenotype at age 10 weeks. In vitro studies revealed C3aR−/-C5aR−/− vs. wildtype cultures had less bone-resorbing osteoclasts and increased bone-forming osteoblasts, which were validated in vivo. To determine whether C3aR alone was critical for the enhanced skeletal outcomes, wildtype vs. C3aR−/− mice were evaluated for osseous tissue outcomes. Paralleling skeletal findings in C3aR−/-C5aR−/− mice, C3aR−/− vs. wildtype mice had an enhanced trabecular bone volume fraction, which was attributed to increased trabecular number. There was elevated osteoblast activity and suppressed osteoclastic cells in C3aR−/− vs. wildtype mice. Furthermore, primary osteoblasts derived from wildtype mice were stimulated with exogenous C3a, which more profoundly upregulated C3ar1 and the pro-osteoclastic chemokine Cxcl1. This study introduces the C3a/C3aR signaling axis as a novel regulator of the young skeleton.

The deep trabecular structure of first metacarpals in extant hominids.

Recent studies have associated subarticular trabecular bone distribution in the extant hominid first metacarpal (Mc1) with observed thumb use, to infer fossil hominin thumb use. Here, we analyze the entire Mc1 to test for interspecific differences in: (1) the absolute volume of trabecular volume fraction, (2) the distribution of the deeper trabecular network, and (3) the distribution of trabeculae in the medullary cavity, especially beneath the Mc1 disto-radial flange. Trabecular bone was imaged using micro-computed tomography in a sample of Homo sapiens (n= 11), Pan paniscus (n= 10), Pan troglodytes (n= 11), Gorilla gorilla (n= 10) and Pongo sp., (n= 7). Using Canonical Holistic Morphometric Analysis (cHMA), we tested for interspecific differences in the trabecular bone volume fraction (BV/TV) and its relative distribution (rBV/TV) throughout the Mc1, including within the head, medullary cavity, and base. P. paniscus had the highest, and H. sapiens the lowest, BV/TV relative to other species. rBV/TV distribution statistically distinguished the radial concentrations and lack of medullary trabecular bone in the H. sapiens Mc1 from all other hominids. H. sapiens and, to a lesser extent, G. gorilla also had a significantly higher trabecular volume beneath the disto-radial flange relative to other hominids. These results are consistent with differences in observed thumb use in these species and may also reflect systemic differences in bone volume fraction. The trabecular bone extension into the medullary cavity and concentrations beneath the disto-radial flange may represent crucial biomechanical signals that will aid in the inference of fossil hominin thumb use.

NADPH oxidase 4 deficiency attenuates experimental osteoarthritis in mice

ObjectiveLow-grade inflammation plays a pivotal role in osteoarthritis (OA) through exposure to reactive oxygen species (ROS). In chondrocytes, NADPH oxidase 4 (NOX4) is one of the major ROS producers. In...

Correlation of the mechanical and structural properties of trabecular bone assessed by wave propagation and imaging methods

This study aimed to assess the correlation of the location- and direction-dependent mechanical and structural properties of trabecular bone using the wave propagation and imaging methods and to propose a non-invasive approach for the assessment of the quality of trabecular bone. Two bovine femur trabecular bone specimens were prepared and tested using the Rayleigh wave propagation tests and CT-scan imaging. The elastic modulus of the specimens was estimated in different regions of interest (ROIs) and wave propagation directions by the solution of the presented Rayleigh wave propagation model. The structural parameters of the specimens were also obtained via the processing of CT-scan images for all of the tested ROIs and directions. The estimated elastic modulus was in the range between 321and 1322 MPa for different ROIs and directions, showing significant heterogeneity and anisotropy of the bone specimens. The Pearson correlation and linear regression analyses were carried out between the obtained mechanical and structural properties, which revealed that the elastic modulus decreased with the trabecular separation and increased with the trabecular thickness and bone volume fraction. A semi-empirical relation was developed to obtain the elastic modulus of trabecular bone using the structural parameters obtained from imaging or vice versa.

Noninvasive monitoring of muscle atrophy and bone metabolic disorders using dual-energy X-ray absorptiometry in diabetic mice.

Tracking metabolic changes in skeletal muscle and bone using animal models of diabetes mellitus (DM) provides important insights for the management of DM complications. In this study, we aimed to establish a method for monitoring changes in body composition characteristics, such as fat mass, skeletal muscle mass (lean mass), bone mineral density, and bone mineral content, during DM progression using a dual-energy X-ray absorptiometry (DXA) system in a mouse model of streptozotocin (STZ)-induced type 1 DM. In the DM model, STZ administration resulted in increased blood glucose levels, increased water and food intake, and decreased body weight. Serum insulin levels were significantly decreased on day 30 of STZ administration. The DXA analysis revealed significant and persistent decreases in fat mass, lower limb skeletal muscle mass, and bone mineral content in DM mice. We measured tibialis anterior (TA) muscle weight and performed a quantitative analysis of tibial microstructure by micro-computed tomography imaging in DM mice. The TA muscle weight of DM mice was significantly lower than that of control mice. In addition, the trabecular bone volume fraction, trabecular thickness, trabecular number, and cortical thickness were significantly decreased in DM mice. Pearson's product-moment correlation coefficient analysis showed a high correlation between the DXA-measured and actual body composition. In conclusion, longitudinal measurement of body composition changes using a DXA system may be useful for monitoring abnormalities in muscle and bone metabolism in animal models of metabolic diseases such as DM mice.

Intake and growth histories modulate bone morphology, microarchitecture, and mineralization in juvenile green turtles (Chelonia mydas)

Abstract Compensatory growth (CG) is accelerated growth that occurs when food availability increases after food restriction. This rapid growth may be associated with sublethal consequences. In this study, we investigated the effects of food restriction and subsequent realimentation and CG on bone structure in juvenile green turtles (Chelonia mydas). Turtles were fed ad libitum food for 12 weeks (AL), restricted food for 12 weeks (R), or restricted food for 5 weeks followed by ad libitum food for 7 weeks (R-AL). R-AL turtles demonstrated partial CG via enhanced food conversion efficiency (FCE) upon realimentation. After the 12th week, gross morphology (GM), microarchitecture, and mineralization of the right humerus of each turtle were analyzed. Many GM measurements (including proximal and maximal bone lengths, bone widths, and shaft thickness), most measurements of bone microarchitecture (excluding cortical and trabecular thickness and trabecular separation), and all mineralization measurements were labile in response to intake. We examined the possibility that changes in nutrient allocation to bone structure during realimentation facilitated CG in previously food-restricted turtles. Restoration of bone lengths was prioritized over restoration of bone widths during CG. Furthermore, restoration of trabecular number, connectivity density, and bone volume fraction was prioritized over restoration of cortical bone volume fraction. Finally, diaphyseal bone mineralization was partially restored, whereas no restoration of epiphyseal bone mineralization occurred during CG. Shifts in nutrient allocation away from certain bone attributes during food restriction that were not rectified when food availability increased probably provided an energy surplus that enhanced the conversion of food to growth and thus powered the CG response. Our study revealed how resource allocation to various bone attributes is prioritized as nutritional conditions change during development. These “priority rules” may have detrimental consequences later in life, indicating that conservation of green turtle foraging grounds should be given high priority.

Examination of the microstructures of the lower cervical facet based on micro-computed tomography: A cadaver study

The cervical facet has complicated 3D microstructures and inhomogeneities. The cervical facet joint, which also participates in the formation, plays a certain role in regulating and limiting the movement of the spine. Correct identification and evaluation of its microstructure can help in the diagnosis of orthopedic disease and predict early phases of fracture risk. To evaluate the safety of the cervical spine by measuring and analyzing the microstructures and morphometric parameters of bone trabeculae in the normal cervical facet with high-resolution 3D micro-computed tomography. Thirty-one sets of C3 to C7 lower cervical vertebrae (155 vertebrae) were scanned using micro-computed tomography. The morphological characteristics and direction of trabecular bone in the facet of the lower cervical vertebrae were observed by selecting and rebuilding the areas of interest, and the changes in the microstructure of the areas of interest were calculated to reveal the structural characteristics and weak areas. Images indicated an ossified center between the superior and inferior articular processes of the lower cervical spine. The cellular bone trabeculae of the articular process had complex reticular microstructures. The trabecular bone plate near the cortical bone was lamellar and relatively dense, and it extended around and transformed into a network structure, and then into the rod-shaped trabecular bone. The rod-shaped trabeculae converged with the plate-shaped trabeculae with only 1 to 2 layers surrounding the trabeculae cavity. Statistical results of the morphological parameters of the trabecular bone showed that trabecular bone volume fraction values were significantly higher for C7 than for C3 to C6 (P < .05). There were significant differences between C7 and C3 to C5 and between C6 and C4 in bone surface area/bone volume (P < .05). There was a significant difference between C7 and C3 to C6 in trabecular bone thickness values (P < .05). The degree of anisotropy value was significantly smaller for C3 than for C6 and C7 (P < .05). The changes in the C3 to C7 microstructure were summarized in this study. The loading capacity and stress of the C7 articular process tended to be limited, and the risk of injury tended to be higher for the C7 articular process.

Trabecular bone ontogeny tracks neural development and life history among humans and non-human primates

Trabecular bone-the spongy bone inside marrow cavities-adapts to its mechanical environment during growth and development. Trabecular structure can therefore be interpreted as a functional record of locomotor behavior in extinct vertebrates. In this paper, we expand upon traditional links between form and function by situating ontogenetic trajectories of trabecular bone in four primate species into the broader developmental context of neural development, locomotor control, and ultimately life history. Our aim is to show that trabecular bone structure provides insights into ontogenetic variation in locomotor loading conditions as the product of interactions between increases in body mass and neuromuscular maturation.Our results demonstrate that age-related changes in trabecular bone volume fraction (BV/TV) are strongly and linearly associated with ontogenetic changes in locomotor kinetics. Age-related variation in locomotor kinetics and BV/TV is in turn strongly associated with brain and body size growth in all species. These results imply that age-related variation in BV/TV is a strong proxy for both locomotor kinetics and neuromuscular maturation. Finally, we show that distinct changes in the slope of age-related variation in bone volume fraction correspond to the age of the onset of locomotion and the age of locomotor maturity.Our findings compliment previous studies linking bone development to locomotor mechanics by providing a fundamental link to brain development and life history. This implies that trabecular structure of fossil subadults can be a proxy for the rate of neuromuscular maturation and major life history events like locomotor onset and the achievement of adult-like locomotor repertoires.

Impact of Alcohol on Bone Health in People Living With HIV: Integrating Clinical Data From Serum Bone Markers With Morphometric Analysis in a Non-Human Primate Model.

People living with HIV (PLWH) represent a vulnerable population to adverse musculoskeletal outcomes due to HIV infection, antiretroviral therapy (ART), and at-risk alcohol use. Developing measures to prevent skeletal degeneration in this group requires a grasp of the relationship between alcohol use and low bone mass in both the PLWH population and its constituents as defined by sex, age, and race. We examined the association of alcohol use with serum biochemical markers of bone health in a diverse cohort of PLWH enrolled in the New Orleans Alcohol Use in HIV (NOAH) study. To explore the effects of alcohol on bone in the context of HIV and ART and the role of estrogen, we conducted a parallel, translational study using simian immunodeficiency virus (SIV)+/ART+ female rhesus macaques divided into four groups: vehicle (Veh)/Sham; chronic binge alcohol (CBA)/Sham; Veh/ovariectomy (OVX); and CBA/OVX. Clinical data showed that both osteocalcin (Ocn) and procollagen type I N-propeptide (PINP) levels were inversely associated with multiple measures of alcohol consumption. Age (>50 years) significantly increased susceptibility to alcohol-associated suppression of bone formation in both female and male PLWH, with postmenopausal status appearing as an additional risk factor in females. Serum sclerostin (Scl) levels correlated positively with measures of alcohol use and negatively with Ocn. Micro-CT analysis of the macaque tibias revealed that although both CBA and OVX independently decreased trabecular number and bone mineral density, only OVX decreased trabecular bone volume fraction and impacted cortical geometry. The clinical data implicate circulating Scl in the pathogenesis of alcohol-induced osteopenia and suggest that bone morphology can be significantly altered in the absence of net change in osteoblast function as measured by serum markers. Inclusion of sophisticated tools to evaluate skeletal strength in clinical populations will be essential to understand the impact of alcohol-induced changes in bone microarchitecture. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

RF06 | PSAT147 Impairments in volumetric bone mineral density, bone microarchitecture, and estimated strength in women with atypical anorexia nervosa

Abstract While anorexia nervosa is associated with impaired skeletal integrity, less is known about the skeletal effects of atypical anorexia nervosa, in which psychological criteria for anorexia nervosa are met, but affected individuals are not low weight. Mean bone mineral density (BMD) is higher in atypical anorexia nervosa than in low-weight anorexia nervosa but lower than in healthy controls. However, it is unknown whether bone microarchitecture and strength are affected. We hypothesized that bone microarchitecture and estimated strength would be impaired in women with atypical anorexia nervosa. This was a cross-sectional study of women ages 21-46 years (n=55): n=28 with atypical anorexia nervosa (body mass index (BMI) &amp;gt;18.5 kg/m2), n=27 healthy, normal weight, eumenorrheic controls. Exclusion criteria included use of oral contraceptives. Areal BMD (aBMD) was assessed by DXA. Volumetric BMD (vBMD), microarchitecture, and failure load (a bone strength estimate) at the distal tibia and radius were assessed by high-resolution peripheral quantitative CT. Median(IQR) BMI was lower [19.4(18.6,20.2) vs 22.2(21.5,23.0), p&amp;lt;0.0001] and median serum 25OH vitamin D level was higher [31(24,39) vs 22(17,25), p=0.0001] in atypical anorexia nervosa than healthy controls. In the atypical anorexia nervosa group, 89% had a history of low weight, 21% had a history of overweight/obesity, 31% had current amenorrhea, and 88% had a history of amenorrhea; median duration of anorexia nervosa was 11(5,14) years. Median lateral spine, total hip, femoral neck, and total radius aBMD Z-scores were lower in atypical anorexia nervosa than healthy controls [lateral spine: -1.1(-2.0,-0.1) vs -0.4(-0.7,0.4), total hip: -0.8(-1.3,0.2) vs 0.2(-0.4,0.7), femoral neck: -0.9(-1.4,0.1) vs -0.1(-0.9,0.6), radius: -0.2(-0.9,0.3) vs 0.1(-0.4,0.6); p≤0.04 for all]. At the tibia, median total, cortical, and trabecular vBMD; cortical thickness; trabecular bone volume fraction; and failure load were lower in atypical anorexia nervosa than healthy controls (p&amp;lt;0.05). At the radius, median trabecular number was lower and trabecular separation was higher in atypical anorexia nervosa than healthy controls (p≤0.04), but there was no difference in failure load between the groups. After controlling for baseline BMI, differences at the radius but not tibia remained significant. At the tibia and radius, median total vBMD, cortical vBMD, and cortical thickness were lower in atypical anorexia nervosa subjects with amenorrhea compared to healthy controls and to atypical anorexia nervosa subjects with eumenorrhea (p≤0.04). Conclusions We demonstrate that, despite normal weight, women with atypical anorexia nervosa have impaired vBMD, microarchitecture, and estimated strength compared to healthy controls, with differences more pronounced at the weight-bearing tibia vs non-weight-bearing radius. Individuals with amenorrhea had additional impairments in the non-weight-bearing radius, suggesting an effect of systemic estrogen deficiency. Our data suggest that current normal weight is not protective against impaired bone structure and strength in atypical anorexia nervosa. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Saturday, June 11, 2022 1:30 p.m. - 1:35 p.m.

Medial tibial plateau sustaining higher physiological stress than the lateral plateau: based on 3D printing and finite element method

BackgroundMedial compartment knee osteoarthritis (KOA) accounts for most KOA cases, and increased trabecular bone volume fraction (BV/TV) is one of the pathological changes in the tibial plateau of KOA. How BV/TV changes before and after the menopause and its effects on medial compartment KOA are yet to be clarified.MethodsTwenty femurs from twenty 12-week-old rats were included. The operated group underwent ovariectomy (to represent the osteoporosis condition), called the O group, and the non-operated group was the normal control, called the N group. Micro-CT scans of the femoral condyles were acquired 12 weeks after the surgery, and the volume of interest (VOI) of medial-, inter-, and lateral-condyle trabeculae were three-dimensional (3D) printed for uniaxial compression mechanical test and simulated by the finite element (FE) method.ResultsThe results demonstrated that the O group indicated poorer trabecular architecture than the N group in three parts of the femoral condyle, especially in the intercondyle. Within the group, the BV/TV, trabecular thickness (Tb.Th), and trabecular number (Tb.N) ratios between the medial and lateral condyles were greater than 1 in both N and O groups. The medial condyle trabeculae's mechanical properties were higher than those of the lateral condyle, and this superiority appears to be broadened under osteoporotic conditions. FE modelling well reproduced these mechanical differentiations.ConclusionsAccording to Wolff's law, the higher BV/TV and mechanical properties of the medial femoral condyle may be due to inherent imbalanced loading on the knee component. Alterations in BV/TV and their corresponding mechanical properties may accompany KOA.

Calcium and phosphorus supplemented diet increases bone volume after thirty days of high speed treadmill exercise in adult mice

Weight-bearing exercise increases bone mass and strength. Increasing bone loading frequency during exercise can strengthen bone. Combining exercise with a calcium- and phosphorus-supplemented diet increases cortical area more than exercise alone in mice. Thus, we hypothesized that combining high-speed treadmill exercise while feeding mice a mineral-supplemented diet would lead to greater cortical area than high-speed exercise on a standard diet and low-speed exercise on a supplemented diet. Fifteen-week old male C57BL/6 mice were assigned to seven groups—(1) baseline, (2) non-exercise fed a control diet, (3) non-exercise fed a supplemented diet, (4) low-speed exercise fed a control diet, (5) low-speed exercise fed a supplemented diet, (6) high-speed exercise fed a control diet, and (7) high-speed exercise fed a supplemented diet. Mice exercised thirty days for 20 min/day at 12 m/min or 20 m/min. Tibiae were assessed by micro-CT and 4-point bending. Cortical area fraction and trabecular bone volume fraction (BV/TV) were significantly increased by the supplemented diet. High-speed exercised mice had significantly lower body weight, with no detrimental effects to bone health. Increasing running speed can decrease body weight while maintaining the benefits of exercise and nutrition on bone health. Running can lower body weight without harming bone health.