Dual energy x ray absorptiometry

Dual-Energy X-ray Absorptiometry (Hologic Inc., Bedford MA, U.S.A.) was used for bone densitometry. After treatment, every subject was examined on supine position to get the BMD (g/cm²) of L2∼4, neck, G.T, hip joint, Ward’s triangle, and focile.

The dual-energy X-ray absorptiometry (Hologic, Marlborough, MA, USA) was used to assess the BMD of the participants. During the BMD measurement, participants were in the supine position. The lumbar spine (L1-L4), total hip, and femoral neck make up the BMD measurement areas. The densitometry scanning was performed by experienced radiographers who were also blinded to clinical information. T-scores were calculated according to the Hologic densitometry reference value. Longitudinal quality control checks were performed daily using whole-body and L1-L4 lumbar spine phantom provided by the manufacturer. Cross-calibration was performed weekly to monitor variations between the systems. The precision error was 1.0% for the BMD measurement. Postmenopausal women with a T score ≤ −2.5 or a history of bone fragility fractures, −2.5 < T-score ≤ −1.0, and T-score >-1.0 were considered to have osteoporosis, osteopenia, and normal BDM, respectively.

Sixteen female C57BL/6 mice (8 weeks old, mean weight of 19 g) were purchased from SLAC Laboratory Animal Company, Ltd. (Shanghai, China) and assigned randomly into two groups: the bilateral ovariectomy group (OVX) and the sham operation control group. The mice were anesthetized with 5% ketamine and underwent bilateral ovariectomy (OVX; eight mice) or sham operation (sham; eight mice) in a bioclean environment. Skin incision was performed in both the OVX and sham groups, and the OVX group underwent ovary removal surgery. The bilateral ovaries from the sham group were identified and placed back into the abdominal cavity. The abdominal incisions were carefully sutured in both groups. The two groups of mice were housed separately with free access to food and drinking water for 12 weeks and prepared for subsequent experiments. The animal experimental procedures were approved in accordance with the Institutional Animal Care and Use Committee of Xiangya Hospital, Central South University (Changsha, Hunan, China). The mice were sacrificed 12 weeks after the operation, and dual-energy X-ray absorptiometry (Hologic, Bedford, MA, USA) was used to measure the femur bone density. Specifically, trabecular number (Tb.N) and trabecular thickness (Tb.Th) were quantified using micro-CT.

Body composition was determined using dual-energy x-ray absorptiometry (Hologic, Waltham, MA, USA). Quality control checks were completed daily, and all scans were performed and analyzed by the same certified densitometry technician (EH). A CPET was used to determine peak oxygen consumption (VO₂peak) and exercise trial workloads. Participants completed 1-minute stages with 20 watt increases until volitional exhaustion. Expired gases were sampled every 15 s using automated gas analyzers (Moxus Modular VO₂ System, AEI Technologies, Pittsburgh, PA, USA) calibrated prior to each test. VO₂peak was determined as the average oxygen consumption across the last minute of the CPET. Heart rate was assessed continuously via 12 lead electrocardiogram (GE Case Cardiosoft v6.6 ECG Diagnostic Systems, Palatine, IL, USA) and rate of perceived (RPE) exertion using the original Borg scale at the end of each stage.