Enzymatic and Non-enzymatic Collagen Cross-Links and Fracture Occurrence in Type 1 Diabetes Patients.

Increased fracture risk in type 1 diabetes (T1D) patients is not fully captured by bone mineral density (BMD) by DXA. Advanced glycation end-products (AGEs) have been implicated in the increased fracture risk in T1D, yet recent publications question this. To test the hypothesis that enzymatic collagen cross-links rather than AGEs correlate with fracture incidence in T1D, we analyzed iliac crest biopsies from sex-matched, fracturing T1D patients (N = 5; T1DFx), 6 non-fracturing T1D patients (T1DNoFx), and 6 healthy subjects, by Raman microspectroscopy as a function of tissue age (based on double fluorescent labels), in intracortical and trabecular bone, to determine pyridinoline (Pyd), ε-N-Carboxymethyl-L-lysine, and pentosidine (PEN)). There were no differences in the clinical characteristics between the T1DFx and T1DNoFx groups. At trabecular forming surfaces, T1DFx patients had higher PEN and Pyd content compared to T1DNoFx ones. Previous studies have shown that elevated PEN does not necessarily correlate with fracture incidence in postmenopausal, long-term T1D patients. On the other hand, the elevated Pyd content in the T1DFx patients would be consistent with published studies showing a significant correlation between elevated trivalent enzymatic collagen cross-links and fracture occurrence independent of BMD. Collagen fibers with high Pyd content are more brittle. Thus, a plausible suggestion is that it is the enzymatic collagen cross-links that either by themselves or in combination with the adverse effects of increased AGE accumulation that result in fragility fracture in T1D.

Dietary Inflammatory Potential and Bone Outcomes in Midwestern Post-Menopausal Women.

Little is known about the inflammatory potential of diet and its relation to bone health. This cross-sectional study examined the association between the inflammatory potential of diet and bone-related outcomes in midwestern, post-menopausal women enrolled in the Heartland Osteoporosis Prevention Study (HOPS) randomized controlled trial. Dietary intake from the HOPS cohort was used to calculate Dietary Inflammatory Index (DII®) scores, which were energy-adjusted (E-DIITM) and analyzed by quartile. The association between E-DII and lumbar and hip bone mineral density (BMD) and lumbar trabecular bone scores (TBS; bone structure) was assessed using ANCOVA, with pairwise comparison to adjust for relevant confounders (age, education, race/ethnicity, smoking history, family history of osteoporosis/osteopenia, BMI, physical activity, and calcium intake). The cohort included 272 women, who were predominately white (89%), educated (78% with college degree or higher), with a mean BMI of 27 kg/m2, age of 55 years, and E-DII score of -2.0 ± 1.9 (more anti-inflammatory). After adjustment, E-DII score was not significantly associated with lumbar spine BMD (p = 0.53), hip BMD (p = 0.29), or TBS at any lumbar location (p > 0.05). Future studies should examine the longitudinal impact of E-DII scores and bone health in larger, more diverse cohorts.

Bone intrinsic material and compositional properties in postmenopausal women diagnosed with long-term Type-1 diabetes.

The incidence of diabetes mellitus and the associated complications are growing worldwide, affecting the patients' quality of life and exerting a considerable burden on health systems. Yet, the increase in fracture risk in type 1 diabetes (T1D) patients is not fully captured by bone mineral density (BMD), leading to the hypothesis that alterations in bone quality are responsible for the increased risk. Material/compositional properties are important aspects of bone quality, yet information on human bone material/compositional properties in T1D is rather sparse. The purpose of the present study is to measure both the intrinsic material behaviour by nanoindentation, and material compositional properties by Raman spectroscopy as a function of tissue age and microanatomical location (cement lines) in bone tissue from iliac crest biopsies from postmenopausal women diagnosed with long-term T1D (N = 8), and appropriate sex-, age-, BMD- and clinically-matched controls (postmenopausal women; N = 5). The results suggest elevation of advanced glycation endproducts (AGE) content in the T1D and show significant differences in mineral maturity / crystallinity (MMC) and glycosaminoglycan (GAG) content between the T1D and control groups. Furthermore, both hardness and modulus by nanoindentation are greater in T1D. These data suggest a significant deterioration of material strength properties (toughness) and compositional properties in T1D compared with controls.

Changes in Dietary Inflammatory Index Score over Time and Cancer Development in Rural Post-Menopausal Women.

Inflammation plays a key role in cancer development. As an important modulator of inflammation, the role of diet should be explored. The purpose of this study was to determine the association between diets with a higher inflammatory potential, as measured by the Dietary Inflammatory Index (DII®), and cancer development in a cohort of rural post-menopausal women. Dietary intake from a randomized controlled trial cohort of rural, post-menopausal women in Nebraska was used to compute energy-adjusted DII (E-DIITM) scores at baseline and four years later (visit 9). A linear mixed model analysis and multivariate logistic regression evaluated the association between E-DII scores (baseline, visit 9, change score) and cancer status. Of 1977 eligible participants, those who developed cancer (n = 91, 4.6%) had a significantly larger, pro-inflammatory change in E-DII scores (Non-cancer: Δ 0.19 ± 1.43 vs. Cancer: Δ 0.55 ± 1.43, p = 0.02). After adjustment, odds of cancer development were over 20% higher in those with a larger change (more pro-inflammatory) in E-DII scores than those with smaller E-DII changes (OR = 1.21, 95% CI [1.02, 1.42], p = 0.02). Shifting to a more pro-inflammatory diet pattern over four years was associated with increased odds of cancer development, but not with E-DII at baseline or visit 9 alone.

Future studies using histomorphometry in type 1 diabetes mellitus.

PURPOSE OF REVIEW: This article reviews the current state of research in type 1 diabetes and bone, focusing on human bone turnover markers and histomorphometry. RECENT FINDINGS: Bone turnover markers have been used for decades to document static bone turnover status in a variety of diseases but especially in diabetes. Two new studies focus on dynamic testing conditions to examine the acute effects of insulin and exercise on bone turnover. Publications of human bone histomorphometry in type 1 diabetes are few but there are several new studies currently underway. SUMMARY: Here, we review the most recent literature on human bone turnover markers and histomorphometry. Low bone turnover is thought to be a major underlying factor in bone fragility in T1DM. Further studies in human transilial bone biopsies will be helpful in determining the mechanisms.

Trabecular bone score and transilial bone trabecular histomorphometry in type 1 diabetes and healthy controls.

Patients with type 1 Diabetes Mellitus (T1DM) have an increased risk of fracture. Little is known about the microarchitecture of trabecular bone in T1DM, which may account for some of the increased risk. We report here a secondary analysis comparing Trabecular Bone Score (TBS) derived from DXA to 2-D histomorphometric and 3-D micro-computerized tomography (CT) variables obtained from iliac biopsies in 83 subjects (29 T1DM and 54 controls). The transilial bone biopsy specimens were fixed, embedded and scanned using a desktop micro-CT at 16 µm resolution. They were then sectioned and quantitative histomorphometry was performed. TBS of the anterior/posterior (AP) spine was obtained by re-analysis of AP lumbar spine DXA images. Overall, there were no differences in TBS, histomorphometry or micro-CT measurements between T1DM and controls. There was a significant association between TBS and 2-D BV/TV using multivariable linear regression after adjusting for group, age and gender. For every 1 unit increase in 2-D BV/TV, TBS increases by 0.0036 units after adjusting for group, gender and age. In conclusion, T1DM does not result in abnormal TBS, histomorphometric or micro-CT variables in young T1DM patients in the absence of diabetic complications. TBS is a good surrogate measure for trabecular microarchitecture.

Supplemental 25-Hydroxycholecalciferol Is More Effective than Cholecalciferol in Raising Serum 25-Hydroxyvitamin D Concentrations in Older Adults.

BACKGROUND: There are few studies directly comparing the pharmacokinetics of 25-hydroxycholecalciferol [25(OH)D3] to cholecalciferol (D3). OBJECTIVES: The primary objectives were to compare the effectiveness of D3 and 25(OH)D3 in raising 25-hydroxyvitamin D [25(OH)D] serum concentrations and achieving steady state. METHODS: This was a randomized, double-blind, active comparator trial of 91 participants (53 females, 38 males), aged 63.3 ± 7.9 y. 25(OH)D3 (10, 15, and 20 µg) and D3 (20 µg) were dosed daily for 6 mo followed by 6 mo of washout. Frequent measurements of serum 25(OH)D were performed. Pharmacokinetic parameters were fitted for each individual and the treatment average was modeled with linear regression using the individual baseline level, sex, and gender as covariates. RESULTS: Mean baseline 25(OH)D was similar in all groups (47.1-49.5 nmol/L). Increases in 25(OH)D to steady state were higher in the 25(OH)D3 groups than in the D3 group [least squares (LS) means (95% CI): 50.1 (43.3-58.0), 72.5 (64.3-81.7), 97.4 (86.6-109.6) nmol/L in 10, 15, and 20 µg/d and 38.7 (33.1-45.2) nmol/L in the D3 group; P = 0.0173, P < 0.0001, P < 0.0001]. The rate to reach steady state was similar in all groups, but the time to reach 25(OH)D concentrations of 75 nmol/L was faster in the higher-dosed 25(OH)D3 groups than in the D3 group (7 and 10 d compared with 40 d, P < 0.0001 and P < 0.0001 for 15 and 20 µg/d). The rate of elimination was 59-109% higher in the 25(OH)D3 groups than in the D3 group. The area under the curve (AUC)/µg dose demonstrated that 25(OH)D3 was 3 times as effective as D3 at raising 25(OH)D concentrations. CONCLUSIONS: 25(OH)D3 is ∼3 times as effective as D3 at raising 25(OH)D concentrations. Once supplementation is discontinued, the elimination rate of 25(OH)D3 is faster than D3. This trial was registered at clinicaltrials.gov as NCT02333682.

The Likelihood of Self-reporting Balance Problems in Those With Advanced Chronic Kidney Disease, Slow Gait Speed, or Low Vitamin D.

OBJECTIVE: The purpose of this study was to determine the prevalence of vitamin D (25(OH)D) and balance deficits in persons with chronic kidney disease (CKD) and the likelihood of self-reporting balance and falling problems, measured gait speed in persons with kidney disease, and low levels of vitamin D and albumin. DESIGN: Analysis of the National Health and Nutrition Examination Survey 1999-2004 data set. SUBJECTS: The study included 8,554 subjects aged >40 years who were categorized into CKD stages based on the glomerular filtration rate (normal kidney function and stages 1 and 2 served as the control group, and stages 3 and 4/5 served as the CKD groups). MAIN OUTCOME MEASURES: Measured 25(OH)D levels, timed 20-feet walk, Romberg standing balance task, and self-reported balance and falling issues. RESULTS: The prevalence of balance deficits was found to be high in this CKD sample, with fail rates increasing with kidney disease severity. Similarly, when examining the relationship between CKD stage and the measurement of balance, fail rates (impaired balance) increased and gait speed decreased with kidney disease severity. In addition, the likelihood of self-reporting a balance and falling problem in the past year was higher in persons who had advanced CKD, were of older age, were of female sex, were with former or current smoking status, had lower 25(OH)D levels, and had lower albumin levels. Similarly, the likelihood of having a 20-feet walk time of more than 8 seconds was associated with those who were older, had higher body mass index, and had lower levels of 25(OH)D and albumin. CONCLUSION: The unique finding of this study is that increased reporting of balance and falling issues (both perceived and measured) and slower gait were found in persons with increased CKD severity and lower 25(OH)D status.

Serum 24,25-dihydroxyvitamin D3 response to native vitamin D2 and D3 Supplementation in patients with chronic kidney disease on hemodialysis.

BACKGROUND & AIMS: While vitamin D deficiency is common in patients with end stage renal disease on dialysis and treatment with Vitamin D2 and Vitamin D3 is becoming increasingly common in these patients, little is known about 24,25(OH)2D3 metabolite production. Some authors report that the CYP24A1 enzyme is upregulated in CKD, but reports of low serum levels of 24,25(OH)2D3 in these patients bring this into question. Lack of substrate or increased clearance of the metabolite have been proposed as possible causes. We report serum 24,25(OH)2D3 levels from three controlled trials of Vitamin D2 and Vitamin D3 supplementation which reached adequate levels of 25(OH)D in patients with end stage renal disease on dialysis. METHODS: 680 samples from three controlled trials of Vitamin D2 or Vitamin D3 supplementation in CKD Stage 5D were available for analysis. The trials used single doses of 50,000 IU Vitamin D3, or 50,000 IU Vitamin D2, or weekly doses of 10,000 IU or 20,000 IU Vitamin D3. Blood samples were drawn at baseline and frequently over the ensuing 3-4 months. Serum 25(OH)D and 24,25(OH)2D3 levels were measured using a novel, very sensitive LC-MS/MS-based method involving derivatization with DMEQ-TAD. Linear mixed effect regression models were used to compare the 3 studies and the interventions within studies over time. RESULTS: The subjects given Vitamin D3 had significant increases in 25(OH)D levels. Serum 24,25(OH)2D3 levels were low at baseline in the renal patients and rose slightly with native vitamin D supplementation, but these levels were lower than reports of 24,25(OH)2D3 in healthy populations. CONCLUSIONS: We conclude that the enzymatic activity of CYP24A1 is abnormal in end stage renal patients on dialysis. These trials were registered on clinicaltrials.govNCT00511225 on 8/1/2007; NCT01325610 on 1/17/2011; and NCT01675557 on 8/28/2012.