YJ Shimada, T Goto, Y Tsugawa, EW Yu, K Yoshida, S Homma, DFM Brown, and K Hasegawa. 2019. “Comparative effectiveness of gastric bypass versus gastric banding on acute care use for cardiovascular disease in adults with obesity.” Nutr Metab Cardiovasc Dis, 29, 5, Pp. 518-526.Abstract
BACKGROUND AND AIMS: Gastric bypass is known to have larger effects on weight and metabolism than gastric banding. However, scarce data exist as to whether the differences are translated into differential risks of cardiovascular disease (CVD)-related morbidities. The objective was to examine whether adults with obesity and CVD who underwent gastric bypass have a lower rate of acute care use (emergency department [ED] visit or unplanned hospitalization) for CVD than those with gastric banding. METHODS AND RESULTS: We performed a comparative effectiveness study of gastric bypass versus banding among adults with obesity and CVD who underwent either surgery, using population-based [ED] and inpatient samples in California, Florida, and Nebraska from 2005 through 2011. The primary outcome was acute care use for CVD during a two-year postoperative period. We constructed negative binomial regression models to compare the event rate during sequential 6-month periods, using gastric banding group as the reference. We identified 11,229 adults with obesity and CVD who underwent gastric bypass and 3896 adults who had gastric banding. Patients with gastric bypass had significantly lower rate of the outcome compared to those with banding in the 7-12 months postoperative period (adjusted rate ratio [aRR] 0.77; 95% confidence interval [CI], 0.61-0.98; P = 0.03). The significant reduction in the rate persisted during 13-18 months (aRR 0.71; 95% CI, 0.57-0.90; P = 0.005) and 19-24 months (aRR 0.66; 95% CI, 0.52-0.82; P < 0.001) after bariatric surgery. CONCLUSION: In this population-based comparative effectiveness study of adults with obesity and CVD, the rate of acute care use for CVD was lower after gastric bypass compared to gastric banding.
Kristin L Popp, Signe Caksa, Adriana Martinez-Betancourt, Amy Yuan, Joy Tsai, Elaine W Yu, and Mary L Bouxsein. 2019. “Cortical Bone Material Strength Index and Bone Microarchitecture in Postmenopausal Women With Atypical Femoral Fractures.” J Bone Miner Res, 34, 1, Pp. 75-82.Abstract
Atypical femoral fractures are rare fractures that occur in the subtrochanteric or diaphyseal region of the femur with minimal or no trauma. Though the association of atypical femoral fractures (AFFs) and bisphosphonate (BP) use is a growing concern in the management of osteoporosis, currently there is little knowledge about which patients may be at risk for an atypical femoral fracture. Given that these fractures initiate in the femoral cortex, we aimed to determine whether cortical bone tissue properties (bone material strength index; BMSi), as measured by in vivo impact microindentation, are altered in atypical fracture patients. We also aimed to identify factors associated with the BMSi measurements. We enrolled postmenopausal women with recent AFFs (n = 15) or hip fractures (Hip Fxs; n = 20), long-term (>5 years) BP users (n = 30), and treatment naïve controls (n = 88). We measured total hip and femoral neck BMD by DXA, cortical bone microstructure at the distal tibia by HR-pQCT, and BMSi at the midtibia by impact microindentation. BMSi values were similar in all groups, with no effects of long-term BP use or lower values in patients with AFFs or Hip Fxs, even after multivariable adjustment. BMSi measurements were independent of age, femoral BMD, duration of BP treatment, vitamin D level, and cortical bone microstructure, including cortical porosity and cortical tissue mineral density. In conclusion, impact microindentation values are not negatively affected by long-term BP use and do not appear to discriminate individuals who suffer AFFs. Thus, our results do not support clinical use of impact microindentation to identify those at risk for AFFs. This remains to be verified in larger studies. © 2018 American Society for Bone and Mineral Research.
Elaine W Yu, Seoyoung C Kim, Daniel J Sturgeon, Katherine G Lindeman, and Joel S Weissman. 2019. “Fracture Risk After Roux-en-Y Gastric Bypass vs Adjustable Gastric Banding Among Medicare Beneficiaries.” JAMA Surg, 154, 8, Pp. 746-753.Abstract
Importance: Roux-en-Y gastric bypass (RYGB) is associated with significant bone loss and may increase fracture risk, whereas substantial bone loss and increased fracture risk have not been reported after adjustable gastric banding (AGB). Previous studies have had little representation of patients aged 65 years or older, and it is currently unknown how age modifies fracture risk. Objective: To compare fracture risk after RYGB and AGB procedures in a large, nationally representative cohort enriched for older adults. Design, Setting, and Participants: This population-based retrospective cohort analysis used Medicare claims data from January 1, 2006, to December 31, 2014, from 42 345 severely obese adults, of whom 29 624 received RYGB and 12 721 received AGB. Data analysis was performed from April 2017 to November 2018. Main Outcomes and Measures: The primary outcome was incident nonvertebral (ie, wrist, humerus, pelvis, and hip) fractures after RYGB and AGB surgery defined using a combination of International Classification of Diseases, Ninth Edition and Current Procedural Terminology 4 codes. Results: Of 42 345 participants, 33 254 (78.5%) were women. With a mean (SD) age of 51 (12) years, recipients of RYGB were younger than AGB recipients (55 [12] years). Both groups had similar comorbidities, medication use, and health care utilization in the 365 days before surgery. Over a mean (SD) follow-up of 3.5 (2.1) years, 658 nonvertebral fractures were documented. The fracture incidence rate was 6.6 (95% CI, 6.0-7.2) after RYGB and 4.6 (95% CI, 3.9-5.3) after AGB, which translated to a hazard ratio (HR) of 1.73 (95% CI, 1.45-2.08) after multivariable adjustment. Site-specific analyses demonstrated an increased fracture risk at the hip (HR, 2.81; 95% CI, 1.82-4.49), wrist (HR, 1.70; 95% CI, 1.33-2.14), and pelvis (HR, 1.48; 95% CI, 1.08-2.07) among RYGB recipients. No significant interactions of fracture risk with age, sex, diabetes status, or race were found. In particular, adults 65 years and older showed similar patterns of fracture risk to younger adults. Sensitivity analyses using propensity score matching showed similar results (nonvertebral fracture: HR 1.75; 95% CI, 1.22-2.52). Conclusions and Relevance: This study of a large, US population-based cohort including a substantial population of older adults found a 73% increased risk of nonvertebral fracture after RYGB compared with AGB, including increased risk of hip, wrist, and pelvis fractures. Fracture risk was consistently increased among RYGB patients vs AGB across different subgroups, and to a similar degree among older and younger adults. Increased fracture risk appears to be an important unintended consequence of RYGB.
Signe Caksa, Amy Yuan, Sara E Rudolph, Elaine W Yu, Kristin L Popp, and Mary L Bouxsein. 2019. “Influence of soft tissue on bone density and microarchitecture measurements by high-resolution peripheral quantitative computed tomography.” Bone, 124, Pp. 47-52.Abstract
High-resolution peripheral quantitative computed tomography (HR-pQCT) is a non-invasive method of measuring volumetric bone mineral density (vBMD) and microarchitecture at the distal radius and tibia. With increasing use of this technology, it is crucial to understand the potential impact of overlying soft tissue on the accuracy of HR-pQCT measures. Thus, we examined the effects of a simulated increase in adiposity (via 6- and 12-mm thick layers of overlying circumferential fat) on HR-pQCT measures of a hydroxyapatite (HA) phantom and in women (n = 20, aged 18-75 years). In the phantom, increasing the amount of overlying fat tissue led to a corresponding decrease in the mean measured density for each HA rod. In women, fat-layering led to a decrease in total vBMD (-2.9 to -3.7%, p < 0.001), cortical vBMD (-1.4% to -5.5%, p < 0.001), and estimated failure load (-1.4 to -5.7%, p = 0.002) at the radius, with similar changes in the tibia. Trabecular microarchitectural measurements were also impacted by simulated adiposity, with fat-layering leading to decreased trabecular thickness and separation and increased trabecular number at the radius (Δ's = 5 to 12%) with more pronounced differences at the tibia (Δ's = 14 to 40%). At the tibia, fat-layering also led to decreased cortical thickness and increased cortical porosity. Altogether, these results demonstrate that overlying adipose tissue can lead to artifacts in bone measurements by HR-pQCT, resulting in an underestimation of vBMD and generally, an overestimation of bone microarchitecture impairment. Therefore, soft tissue artifact should be considered when interpreting HR-pQCT results, particularly in those with high BMI and/or marked changes in adiposity.
Elaine W Yu. 2018. “Bariatric Surgery: Weighing In on Bone Loss.” J Bone Miner Res, 33, 6, Pp. 973-974.
Tamara D Rozental, Kempland C Walley, Serkalem Demissie, Signe Caksa, Adriana Martinez-Betancourt, Amber M Parker, Joy N Tsai, Elaine W Yu, and Mary L Bouxsein. 2018. “Bone Material Strength Index as Measured by Impact Microindentation in Postmenopausal Women With Distal Radius and Hip Fractures.” J Bone Miner Res, 33, 4, Pp. 621-626.Abstract
We tested whether cortical bone tissue properties assessed by in vivo impact microindentation would distinguish postmenopausal women with recent distal radius (DRF) or hip fracture (HF) from nonfracture controls (CONT). We enrolled postmenopausal women with recent DRF (n = 57), HF (n = 41), or CONT (n = 93), and used impact microindentation to assess bone material strength index (BMSi) at the anterior surface of the mid-tibia diaphysis. Areal bone mineral density (aBMD) (g/cm ) of the femoral neck (FN), total hip (TH), and lumbar spine (LS) were measured by dual-energy X-ray absorptiometry (DXA). HF and DRF subjects had significantly lower BMD than CONT at all sites (-5.6% to -8.2%, p < 0.001 for all). BMSi was 4% lower in DRF compared to CONT (74.36 ± 8.77 versus 77.41 ± 8.79, p = 0.04). BMSi was similarly lower in HF versus CONT, but the difference did not reach statistical significance (74.62 ± 8.47 versus 77.41 ± 8.79, p = 0.09). Lower BMSi was associated with increased risk of DRF (unadjusted OR, 1.43; 95% CI, 1.02 to 2.00, per SD decrease, p = 0.04), and remained statistically significant after adjustment for age, age and BMI, and age, BMI, and FN BMD (OR = 1.48 to 1.55). Lower BMSi tended to be associated with HF, but only reached borderline significance (unadjusted OR = 1.39; 95% CI, 0.96 to 2.01, p = 0.08). These results provide strong rationale for future investigations aimed at assessing whether BMSi can predict fracture in prospective studies and improve identification of women at risk for fragility fractures. © 2017 American Society for Bone and Mineral Research.
Katherine G Lindeman, Logan B Greenblatt, Caroline Rourke, Mary L Bouxsein, Joel S Finkelstein, and Elaine W Yu. 2018. “Longitudinal 5-Year Evaluation of Bone Density and Microarchitecture After Roux-en-Y Gastric Bypass Surgery.” J Clin Endocrinol Metab, 103, 11, Pp. 4104-4112.Abstract
Context: Bone health declines in the initial years after Roux-en-Y gastric bypass (RYGB), but long-term skeletal effects are unclear. Objective: To document longitudinal changes in bone mineral density (BMD) and microarchitecture 5 years after RYGB. Design, Setting, and Participants: Prospective 5-year observational study of 21 adults with severe obesity receiving RYGB at an academic medical center. Main Outcome Measures: Spine and hip areal BMD were measured by dual-energy X-ray absorptiometry, and trabecular volumetric BMD (vBMD) of the spine was assessed by quantitative CT (QCT). We measured vBMD and microarchitecture of the distal radius and tibia by high-resolution peripheral QCT in a subset of subjects. Serum type I collagen C-terminal telopeptide (CTX) and procollagen type I N-terminal propeptide (P1NP) were also measured. Results: Areal BMD declined by -7.8% ± 7.6% at the spine and -15.3% ± 6.3% at the total hip by 5 years after RYGB (P ≤ 0.001), although the rate of bone loss slowed in later years. Trabecular spine vBMD decreased by -12.1% ± 12.3% by 5 years (P ≤ 0.001). At peripheral sites, vBMD continued to decrease steadily throughout 5 years, with parallel declines in cortical and trabecular microarchitecture, leading to decreases in estimated failure load of -20% and -13% at the radius and tibia, respectively (P < 0.001). Five years after RYGB, CTX and P1NP were 150% and 34% above baseline (P < 0.001 and P = 0.017, respectively). Conclusions: Sustained high-turnover bone loss and bone microarchitectural deterioration occur in the 5 years after RYGB. Adults receiving RYGB warrant assessment of bone health.
Paula PB Silva, Fatemeh G Amlashi, Elaine W Yu, Karen J Pulaski-Liebert, Anu V Gerweck, Pouneh K Fazeli, Elizabeth Lawson, Lisa B Nachtigall, Beverly MK Biller, Karen K Miller, Anne Klibanski, Mary Bouxsein, and Nicholas A Tritos. 2017. “Bone microarchitecture and estimated bone strength in men with active acromegaly.” Eur J Endocrinol, 177, 5, Pp. 409-420.Abstract
CONTEXT: Both acromegaly and adult growth hormone deficiency (GHD) are associated with increased fracture risk. Sufficient data are lacking regarding cortical bone microarchitecture and bone strength, as assessed by microfinite element analysis (µFEA). OBJECTIVE: To elucidate both cortical and trabecular bone microarchitecture and estimated bone strength in men with active acromegaly or GHD compared to healthy controls. DESIGN AND SUBJECTS: Cross-sectional study at a clinical research center, including 48 men (16 with acromegaly, 16 with GHD and 16 healthy controls). OUTCOME MEASURES: Areal bone mineral density (aBMD), cortical and trabecular bone microarchitecture and estimated bone strength (µFEA) at the radius and tibia. RESULTS: aBMD was not different between the 3 groups at any skeletal site. At the radius, patients with acromegaly had greater cortical area ( < 0.0001), cortical thickness ( = 0.0038), cortical pore volume ( < 0.0001) and cortical porosity ( = 0.0008), but lower trabecular bone density ( = 0.0010) compared to controls. At the tibia, patients with acromegaly had lower trabecular bone density ( = 0.0082), but no differences in cortical bone microstructure. Compressive strength and failure load did not significantly differ between groups. These findings persisted after excluding patients with hypogonadism. Bone microarchitecture was not deficient in patients with GHD. CONCLUSIONS: Both cortical and trabecular microarchitecture are altered in men with acromegaly. Our data indicate that GH excess is associated with distinct effects in cortical vs trabecular bone compartments. Our observations also affirm the limitations of aBMD testing in the evaluation of patients with acromegaly.
Melissa S Putman, Elaine W Yu, David Lin, Karin Darakananda, Joel S Finkelstein, and Mary L Bouxsein. 2017. “Differences in Trabecular Microstructure Between Black and White Women Assessed by Individual Trabecular Segmentation Analysis of HR-pQCT Images.” J Bone Miner Res, 32, 5, Pp. 1100-1108.Abstract
Black women have lower fracture risk compared with white women, which may be partly explained by improved volumetric bone mineral density (vBMD) and bone microarchitecture primarily within the cortical bone compartment. To determine if there are differences in trabecular microstructure, connectivity, and alignment according to race/ethnicity, we performed individual trabecular segmentation (ITS) analyses on high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the distal radius and tibia in 273 peri- and postmenopausal black (n = 100) and white (n = 173) women participating in the Study of Women's Health Across the Nation in Boston. Unadjusted analyses showed that black women had greater trabecular plate volume fraction, plate thickness, plate number density, and plate surface area along with greater axial alignment of trabeculae, whereas white women had greater trabecular rod tissue fraction (p < 0.05 for all). Adjustment for clinical covariates augmented these race/ethnicity-related differences in plates and rods, such that white women had greater trabecular rod number density and rod-rod connectivity, whereas black women continued to have superior plate structural characteristics and axial alignment (p < 0.05 for all). These differences remained significant after adjustment for hip BMD and trabecular vBMD. In conclusion, black women had more plate-like trabecular morphology and higher axial alignment of trabeculae, whereas white women had more rod-like trabeculae. These differences may contribute to the improved bone strength and lower fracture risk observed in black women. © 2016 American Society for Bone and Mineral Research.
Miriam A Bredella, Logan B Greenblatt, Alireza Eajazi, Martin Torriani, and Elaine W Yu. 2017. “Effects of Roux-en-Y gastric bypass and sleeve gastrectomy on bone mineral density and marrow adipose tissue.” Bone, 95, Pp. 85-90.Abstract
Bariatric surgery is associated with bone loss but skeletal consequences may differ between Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), the two most commonly performed bariatric procedures. Furthermore, severe weight loss is associated with high marrow adipose tissue (MAT); however, MAT is also increased in visceral adiposity. The purpose of our study was to determine the effects of RYGB and SG on BMD and MAT. We hypothesized that both bariatric procedures would lead to a decrease in BMD and MAT. We studied 21 adults with morbid obesity (mean BMI 44.1±5.1kg/m(2)) prior to and 12months after RYGB (n=11) and SG (n=10). All subjects underwent DXA and QCT of the lumbar spine and hip to assess aBMD and vBMD. Visceral (VAT) and subcutaneous (SAT) adipose tissue was quantified at L1-L2. MAT of the lumbar spine and femur was assessed by 1H-MR spectroscopy. Calcitropic hormones and bone turnover markers were determined. At 12months after surgery, mean weight and abdominal fat loss was similar between the RYGB and SG groups. Mean serum calcium, 25(OH)-vitamin D, and PTH levels were unchanged after surgery and within the normal range in both groups. Bone turnover markers P1NP and CTX increased within both groups and P1NP increased to a greater extent in the RYGB group (p=0.03). There were significant declines from baseline in spine aBMD and vBMD within the RYGB and SG groups, although the changes were not significantly different between groups (p=0.3). Total hip and femoral neck aBMD by DXA decreased to a greater extent in the RYGB than the SG group (p<0.04) although the change in femoral vBMD by QCT was not significantly different between groups (p>0.2). MAT content of the lumbar spine and femoral diaphysis did not change from baseline in the RYGB group but increased after SG (p=0.03). Within the SG group, 12-month change in weight and VAT were positively associated with 12-month change in MAT (p<0.04), suggesting that subjects with less weight and VAT loss had higher MAT. In conclusion, RYGB and SG are associated with declines in lumbar spine BMD, however, the changes are not significantly different between the groups. RYGB may be associated with greater decline of aBMD at the total hip and femoral neck compared to SG. MAT content increased after SG and this was associated with lower weight and VAT loss.
Altan Ercan, Wendy M Kohrt, Jing Cui, Kevin D Deane, Marija Pezer, Elaine W Yu, Jonathan S Hausmann, Harry Campbell, Ursula B Kaiser, Pauline M Rudd, Gordan Lauc, James F Wilson, Joel S Finkelstein, and Peter A Nigrovic. 2017. “Estrogens regulate glycosylation of IgG in women and men.” JCI Insight, 2, 4, Pp. e89703.Abstract
The immunologic potency of IgG is modulated by glycosylation, but mechanisms regulating this process are undefined. A role for sex hormones is suggested by differences in IgG glycans between women and men, most prominently with respect to galactose. We therefore assessed IgG galactosylation in 713 healthy adults from 2 cohorts as well as in 159 subjects from 4 randomized controlled studies of endocrine manipulation: postmenopausal women receiving conjugated estrogens, raloxifene, or placebo; premenopausal women deprived of gonadal hormones with leuprolide and treated with estradiol or placebo; men deprived of gonadal hormones with goserelin and given testosterone or placebo; and men deprived of gonadal hormones with goserelin and given testosterone or placebo together with anastrozole to block conversion of testosterone to estradiol. Menopause was associated with an increase in agalactosylated IgG glycans, particularly in the most abundant fucosylated nonbisected (G0F) glycoform. Conjugated estrogens and raloxifene reduced G0F glycans in postmenopausal women, while in premenopausal women leuprolide increased G0F glycans in a manner reversed by estradiol. Among men, goserelin increased G0F glycans, an effect blocked by testosterone through conversion to estradiol. These results establish estrogens as an in vivo modulator of IgG galactosylation in both women and men, defining a pathway by which sex modulates immunity.
Elaine W Yu, Moa P Lee, Joan E Landon, Katherine G Lindeman, and Seoyoung C Kim. 2017. “Fracture Risk After Bariatric Surgery: Roux-en-Y Gastric Bypass Versus Adjustable Gastric Banding.” J Bone Miner Res, 32, 6, Pp. 1229-1236.Abstract
The long-term consequences of bariatric surgery on fracture risk are unclear but are likely to vary by procedure type. In physiologic studies, Roux-en-Y gastric bypass (RYGB) and adjustable gastric banding (AGB) have differential effects on rates of bone loss. Therefore, our objective was to compare fracture risk in obese adults after RYGB and AGB procedures. Using claims data from a US commercial health plan, we analyzed rates of nonvertebral fractures within a propensity score-matched cohort (n = 15,032) of morbidly obese adults who received either RYGB or AGB surgery between 2005 and 2013. A total of 281 nonvertebral fractures occurred during a mean follow-up time of 2.3 ± 1.9 years. RYGB patients had an increased risk of nonvertebral fracture (hazard ratio [HR] = 1.43, 95% confidence interval [CI] 1.13-1.81) compared with AGB patients. In fracture site-specific analyses, RYGB patients had increased risk of fracture at the hip (HR = 1.54, 95% CI 1.03-2.30) and wrist (HR = 1.45, 95% CI 1.01-2.07). Nonvertebral fracture risk associated with RYGB manifested >2 years after surgery and increased in subsequent years, with the highest risk in the fifth year after surgery (HR = 3.91, 95% CI 1.58-9.64). In summary, RYGB is associated with a 43% increased risk of nonvertebral fracture compared with AGB, with risk increasing >2 years after surgery. Fracture risk should be considered in risk/benefit discussions of bariatric surgery, particularly among patients with high baseline risk of osteoporosis who are deciding between RYGB and AGB procedures. © 2017 American Society for Bone and Mineral Research.
Ahmad Al-Sukaini, Nuno Rui Paulino Pereira, Elaine W Yu, Ivan Chebib, Miriam A Bredella, and Joseph Schwab. 2017. “Idiopathic tumoral calcinosis-like lesion in the lower cervical spine causing acute central cord syndrome: case report.” J Neurosurg Spine, 26, 1, Pp. 97-102.Abstract
A 57-year-old male presented with recurrent falls, bilateral lower-limb paresthesia, and severe neck pain. Imaging revealed a mass compressing his spinal cord. He was admitted for further workup for spinal cord compression. Within 24 hours of admission, he developed upper-extremity weakness while maintaining lower-extremity function. He underwent urgent decompression of his spinal cord. During exposure, a white, creamy odorless substance was noted. This same substance was found under pressure within the spinal canal. The mass was grossly removed, and the patient's weakness improved postoperatively. Based on the clinical picture, intraoperative presentation, and final histological examination, idiopathic tumoral calcinosis-like lesion was considered as the most appropriate diagnosis.
Elaine W Yu, Logan Greenblatt, Alireza Eajazi, Martin Torriani, and Miriam A Bredella. 2017. “Marrow adipose tissue composition in adults with morbid obesity.” Bone, 97, Pp. 38-42.Abstract
Patients with type 2 diabetes mellitus (T2DM) have increased fracture risk despite normal or increased bone mineral density (BMD). Elevations in marrow adipose tissue (MAT) and declines in MAT unsaturation are both associated with increased skeletal fragility. The objective of our study was to characterize the quantity and composition of MAT in adults with morbid obesity and T2DM, and to evaluate determinants of MAT. We studied 21 adults with morbid obesity prior to bariatric surgery, 8 of whom had T2DM. All subjects underwent 1H-MR spectroscopy of the lumbar spine and femur for assessment of MAT and dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT) of the lumbar spine and hip for assessment of areal BMD (aBMD) and volumetric BMD (vBMD). Visceral (VAT) and subcutaneous adipose tissue (SAT) were quantified by CT at L1-L2. Subjects with T2DM had higher vBMD of the femoral neck and higher total MAT at the lumbar spine and femoral metaphysis compared to non-diabetic controls (p≤0.04). Lipid unsaturation index (UI) was significantly lower at the femoral diaphysis in T2DM (p=0.03). Within the entire cohort, HbA1c was positively associated with MAT (p≤0.03), and age was associated with higher MAT and lower MAT unsaturation (p≤0.05). Lumbar spine vBMD was inversely associated with lumbar spine MAT (p=0.04). There was an inverse association between SAT and diaphyseal MAT (p<0.05) while there were no associations with VAT. Subjects with morbid obesity and T2DM have higher MAT with a lower proportion of unsaturated lipids, despite higher femoral neck vBMD. MAT is positively associated with age and HbA1c, and inversely associated with vBMD, suggesting that MAT may serve as an imaging biomarker of skeletal health and metabolic risk.
VV Shanbhogue, JS Finkelstein, ML Bouxsein, and EW Yu. 5/31/2016. “Association between insulin resistance and bone structure in non-diabetic postmenopausal women.” Journal of Clinical Endocrinology and Metabolism, 101, 8, Pp. 3114-3122.
Elaine W Yu, Jill S Carmody, Daniel J Brooks, Scott LaJoie, Lee M Kaplan, and Mary L Bouxsein. 2016. “Cortical and trabecular deterioration in mouse models of Roux-en-Y gastric bypass.” Bone, 85, Pp. 23-8.Abstract
Roux-en-Y gastric bypass (RYGB) is a profoundly effective treatment for severe obesity, but results in significant bone loss in patients. Developing a murine model that recapitulates this skeletal phenotype will provide a robust tool with which to study the physiologic mechanisms of this bone loss. We studied adult male C57BL/6J mice who underwent either RYGB or sham operation. Twelve weeks after surgery, we characterized biochemical bone markers (parathyroid hormone, PTH; C-telopeptide, CTX; and type 1 procollagen, P1NP) and bone microarchitectural parameters as measured by microcomputed tomography. RYGB-treated mice had significant trabecular and cortical bone deficits compared with sham-operated controls. Although adjustment for final body weight eliminated observed cortical differences, the trabecular bone volume fraction remained significantly lower in RYGB mice even after weight adjustment. PTH levels were similar between groups, but RYGB mice had significantly higher indices of bone turnover than sham controls. These data demonstrate that murine models of RYGB recapitulate patterns of bone loss and turnover that have been observed in human clinical studies. Future studies that exploit this murine model will help delineate the alterations in bone metabolism and mechanisms of bone loss after RYGB.
Elaine W Yu, Marlene Wewalka, Su-Ann Ding, Donald C Simonson, Kathleen Foster, Jens J Holst, Ashley Vernon, Allison B Goldfine, and Florencia Halperin. 2016. “Effects of Gastric Bypass and Gastric Banding on Bone Remodeling in Obese Patients With Type 2 Diabetes.” J Clin Endocrinol Metab, 101, 2, Pp. 714-22.Abstract
CONTEXT: Roux-en-Y gastric bypass (RYGB) leads to high-turnover bone loss, but little is known about skeletal effects of laparoscopic adjustable gastric banding (LAGB) or mechanisms underlying bone loss after bariatric surgery. OBJECTIVE: To evaluate effects of RYGB and LAGB on fasting and postprandial indices of bone remodeling. DESIGN AND SETTING: Ancillary investigation of a prospective study at 2 academic institutions. PARTICIPANTS: Obese adults aged 21-65 years with type 2 diabetes who underwent RYGB (n = 11) or LAGB (n = 8). OUTCOMES: Serum C-terminal telopeptide (CTX), procollagen type 1 N-terminal propeptide (P1NP), and PTH were measured during a mixed meal tolerance test at baseline, 10 days and 1 year after surgery. Changes in 25-hydroxyvitamin D, polypeptide YY (PYY), glucagon-like peptide-1, glucose-dependent insulinotropic peptide, and insulin were also assessed. RESULTS: Fasting CTX increased 10 days after RYGB but not LAGB (+69 ± 23% vs +12±12%, P < .001), despite comparable weight loss at that time. By 1 year, fasting CTX and P1NP increased more after RYGB than LAGB (CTX +221 ± 60% vs +15 ± 6%, P<0.001; P1NP +93 ± 25% vs -9 ± 10%, P < .001) and weight loss was greater with RYGB. Changes in CTX were independent of PTH and 25-hydroxyvitamin D but were associated with increases in fasting PYY. Postprandial suppression of CTX was more pronounced after RYGB than LAGB at 10 days and 1 year postoperatively. CONCLUSIONS: RYGB is accompanied by early increases in fasting indices of bone remodeling, independent of weight loss or changes in PTH or 25-hydroxyvitamin D. LAGB did not affect bone markers. PYY and other enterohormonal signals may play a role in RYGB-specific skeletal changes.
Joel S Finkelstein, Hang Lee, Benjamin Z Leder, Sherri-Ann M Burnett-Bowie, David W Goldstein, Christopher W Hahn, Sarah C Hirsch, Alex Linker, Nicholas Perros, Andrew B Servais, Alexander P Taylor, Matthew L Webb, Jonathan M Youngner, and Elaine W Yu. 2016. “Gonadal steroid-dependent effects on bone turnover and bone mineral density in men.” J Clin Invest, 126, 3, Pp. 1114-25.Abstract
BACKGROUND: Severe gonadal steroid deficiency induces bone loss in adult men; however, the specific roles of androgen and estrogen deficiency in hypogonadal bone loss are unclear. Additionally, the threshold levels of testosterone and estradiol that initiate bone loss are uncertain. METHODS: One hundred ninety-eight healthy men, ages 20-50, received goserelin acetate, which suppresses endogenous gonadal steroid production, and were randomized to treatment with 0, 1.25, 2.5, 5, or 10 grams of testosterone gel daily for 16 weeks. An additional cohort of 202 men was randomized to receive these treatments plus anastrozole, which suppresses conversion of androgens to estrogens. Thirty-seven men served as controls and received placebos for goserelin and testosterone. Changes in bone turnover markers, bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA), and BMD by quantitative computed tomography (QCT) were assessed in all men. Bone microarchitecture was assessed in 100 men. RESULTS: As testosterone dosage decreased, the percent change in C-telopeptide increased. These increases were considerably greater when aromatization of testosterone to estradiol was also suppressed, suggesting effects of both testosterone and estradiol deficiency. Decreases in DXA BMD were observed when aromatization was suppressed but were modest in most groups. QCT spine BMD fell substantially in all testosterone-dose groups in which aromatization was also suppressed, and this decline was independent of testosterone dose. Estradiol deficiency disrupted cortical microarchitecture at peripheral sites. Estradiol levels above 10 pg/ml and testosterone levels above 200 ng/dl were generally sufficient to prevent increases in bone resorption and decreases in BMD in men. CONCLUSIONS: Estrogens primarily regulate bone homeostasis in adult men, and testosterone and estradiol levels must decline substantially to impact the skeleton. TRIAL REGISTRATION:, NCT00114114. FUNDING: AbbVie Inc., AstraZeneca Pharmaceuticals LP, NIH.
EW Yu, MS Putman, N Derrico, G Abrishamanian-Garcia, JS Finkelstein, and ML Bouxsein. 2015. “Defects in cortical microarchitecture among African-American women with type 2 diabetes.” Osteoporos Int, 26, 2, Pp. 673-9.Abstract
SUMMARY: Patients with type 2 diabetes mellitus (DM2) have increased fracture risk. We found that African-American women with DM2 have increased cortical porosity and lower cortical bone density at the radius than non-diabetic controls. These cortical deficits are associated with hyperglycemia and may contribute to skeletal fragility associated with DM2. INTRODUCTION: Fracture risk is increased in patients with type 2 diabetes mellitus (DM2) despite normal areal bone mineral density (aBMD). DM2 is more common in African-Americans than in Caucasians. It is not known whether African-American women with DM2 have deficits in bone microstructure. METHODS: We measured aBMD at the spine and hip by DXA, and volumetric BMD (vBMD) and microarchitecture at the distal radius and tibia by HR-pQCT in 22 DM2 and 78 non-diabetic African-American women participating in the Study of Women Across the Nation (SWAN). We also measured fasting glucose and HOMA-IR. RESULTS: Age, weight, and aBMD at all sites were similar in both groups. At the radius, cortical porosity was 26% greater, while cortical vBMD and tissue mineral density were lower in women with DM2 than in controls. There were no differences in radius total vBMD or trabecular vBMD between groups. Despite inferior cortical bone properties at the radius, FEA-estimated failure load was similar between groups. Tibia vBMD and microarchitecture were also similar between groups. There were no significant associations between cortical parameters and duration of DM2 or HOMA-IR. However, among women with DM2, higher fasting glucose levels were associated with lower cortical vBMD (r=-0.54, p=0.018). CONCLUSIONS: DM2 and higher fasting glucose are associated with unfavorable cortical bone microarchitecture at the distal radius in African-American women. These structural deficits may contribute to the increased fracture risk among women with DM2. Further, our results suggest that hyperglycemia may be involved in mechanisms of skeletal fragility associated with DM2.
Martin Torriani, Adriana L Oliveira, Debora C Azevedo, Miriam A Bredella, and Elaine W Yu. 2015. “Effects of Roux-en-Y gastric bypass surgery on visceral and subcutaneous fat density by computed tomography.” Obes Surg, 25, 2, Pp. 381-5.Abstract
We aimed to test the hypothesis that noninvasive fat density by computed tomography (CT) increases after Roux-en-Y gastric bypass (RYGB) and correlates with improved cardiometabolic risk. We examined 21 obese adults before and 12 months after RYGB and 16 obese nonsurgical controls followed for 12 months. Visceral (VAT) and subcutaneous adipose tissue (SAT) density increased after RYGB (P < 0.0001) while remaining stable in controls (P ≥ 0.1). In RYGB subjects, 12-month increase in VAT density correlated with decreased C-reactive protein (CRP) independent of change in VAT area or BMI (both P < 0.05). Twelve-month increase in SAT density correlated with increased HDL cholesterol independent of change in SAT area (P = 0.048), BMI (P = 0.03), or statin use (P = 0.002), and 1 unit increase in SAT density had increased odds of higher total abdominal fat loss (P = 0.002).