Effect of vitamin D supplementation or fortification on bone turnover markers in women: a systematic review and meta-analysis

Vitamin D is a vital indicator of musculoskeletal health, as it plays an important role through the regulation of bone and mineral metabolism. This meta-analysis was performed to investigate the effects of vitamin D supplementation/fortification on bone turnover markers in women. All human randomised clinical trials reported changes in bone resorption markers (serum C-terminal telopeptide of type-I collagen (sCTX) and urinary type I collagen cross-linked N-telopeptide (uNTX)) or bone formation factors (osteocalcin (OC), bone alkaline phosphatase (BALP) and procollagen type-1 intact N-terminal propeptide (P1NP)) following vitamin D administration in women (aged ≥ 18 years) were considered. Mean differences (MD) and their respective 95 % CI were calculated based on fixed or random effects models according to the heterogeneity status. Subgroup analyses, meta-regression models, sensitivity analysis, risk of bias, publication bias and the quality of the included studies were also evaluated. We found that vitamin D supplementation had considerable effect on sCTX (MD: -0·038, n 22) and OC (MD: -0·610, n 24) with high heterogeneity and uNTX (MD: -8·188, n 6) without heterogeneity. Our results showed that age, sample size, dose, duration, baseline vitamin D level, study region and quality of studies might be sources of heterogeneity in this meta-analysis. Subgroup analysis also revealed significant reductions in P1NP level in dose less than 600 μg/d and larger study sample size (>100 participants). Moreover, no significant change was found in BALP level. Vitamin D supplementation/fortification significantly reduced bone resorption markers in women. However, results were inconsistent for bone formation markers.

Icariin attenuates thioacetamide‑induced bone loss via the RANKL‑p38/ERK‑NFAT signaling pathway

There is an increasing incidence of destructive bone disease caused by osteoclast proliferation. This is characterized by reduced bone mass and imbalance of bone homeostasis. Icariin (ICA), a flavonoid compound isolated from Epimedium, has anti‑osteoporosis activity and inhibits the formation of osteoclasts and bone resorption. The purpose of the present study was to investigate the protective effect of ICA on osteoclastic differentiation induced by thioacetamide (TAA) and its possible mechanism in Sprague Dawley (SD) rats. In the present study, SD rats were intraperitoneally injected with TAA (300 mg/kg) for the bone loss model, treated with ICA (600 mg/kg, intragastric gavage) in the ICA group and TAA+ICA group for treatment of bone loss for 6 weeks. Indexes associated with bone metabolism, such as alkaline phosphatase, N‑terminal telopeptide of type‑I collagen (NTX‑I), calcium (Ca), phosphorus (P) and magnesium (Mg) in the serum, were detected. Osteoclast differentiation of femoral tissues was detected by hematoxylin and eosin and tartrate‑resistant acid phosphatase staining. The femoral bone mass was evaluated using a three‑point bending test and micro computed tomography. Western blotting was used to detect the expression levels of osteoclast‑related proteins in each group. In the rats treated with TAA, the serum concentrations of Ca, P and Mg were decreased, the serum concentration of NTX‑I was increased, osteoclast differentiation of the femur was increased, femur bone stress and bone mass were decreased and the bone loss and osteoclast formation were reduced after ICA treatment. In addition, ICA inhibited the protein expression of receptor activator of nuclear factor κ‑Β ligand (RANKL), receptor activator of nuclear factor κ‑B (RANK), p38, ERK, c‑Fos and nuclear factor of activated T cells 1 (NFATc1) in the femur of rats treated with TAA. The results suggested that ICA may inhibit osteoclast differentiation by downregulating the RANKL‑p38/ERK‑NFAT signaling pathway and prevent TAA‑induced bone loss. The results are helpful to understand the mechanism of osteoclast differentiation induced by TAA, as well as the antiresorptive activity and molecular mechanism of ICA, and to provide new ideas for the treatment of osteolytic diseases.

Sclerostin and bone turnover markers response to cycling and running at the same moderate-to-vigorous exercise intensity in healthy men

BACKGROUND

Recreational cycling is a popular activity which stimulates and improves cardiovascular fitness. The corresponding benefits for bone are unclear.

PURPOSE

This study examined the effect of running (high-impact) vs. cycling (low-impact), at the same moderate-to-vigorous exercise intensity, on markers of bone formation (N-terminal propeptide of type I collagen, PINP) and bone resorption (C-telopeptide of type I collagen, CTX-1), a non-collagenous bone remodeling marker (osteocalcin), as well as bone-modulating factors, including parathyroid hormone (PTH), irisin (myokine) and sclerostin (osteokine).

METHODS

Thirteen healthy men (23.7 ± 1.0 y) performed two progressive exercise tests to exhaustion (peak VO₂) on a cycle ergometer (CE) and on a treadmill (TM). On subsequent separate days, in randomized order, participants performed 30-min continuous running or cycling at 70% heart rate reserve (HRR). Blood was drawn before, immediately post- and 1 h into recovery.

RESULTS

PTH transiently increased (CE, 51.7%; TM, 50.6%) immediately after exercise in both exercise modes. Sclerostin levels increased following running only (27.7%). Irisin increased following both running and cycling. In both exercise modes, CTX-1 decreased immediately after exercise, with no significant change in PINP and osteocalcin.

CONCLUSION

At the same moderate-to-vigorous exercise intensity, running appears to result in a greater transient sclerostin response compared with cycling, while the responses of bone markers, PTH and irisin are similar. The longer-term implications of this differential bone response need to be further examined.

Peptide Biomarkers for the Diagnosis of Dengue Infection

In a world with an increasing population at risk of exposure to arthropod-borne flaviviruses, access to timely and accurate diagnostic tests would impact profoundly on the management of cases. Twenty peptides previously identified using a flavivirus proteome-wide microarray were evaluated to determine their discriminatory potential to detect dengue virus (DENV) infection. This included nine peptides recognized by IgM antibodies (PM peptides) and 11 peptides recognized by IgG antibodies (PG peptides). A bead-based multiplex peptide immunoassay (MPIA) using the Luminex technology was set-up to determine Ab binding levels to each of these peptides in a panel of 323 carefully selected human serum samples. Sera are derived from individuals either infected with different viruses, namely, the four DENV serotypes, Zika virus (ZIKV), yellow fever virus (YFV), chikungunya virus (CHIKV), West Nile virus (WNV) and Human immunodeficiency virus (HIV), or receiving vaccination against YFV, tick-borne encephalitis (TBEV), and Japanese encephalitis virus (JEV). Additionally, a set of healthy controls were included. We targeted a minimum specificity of 80% for all the analysis. The PG-9 peptide had the best sensitivity (73%) when testing DENV sera from acute patients (A-DENV; <8 days since symptom onset). With sera from convalescent DENV patients (C-DENV; >10 days since symptom onset) the FPG-1 peptide was the best seromarker with a sensitivity of 86%. When combining all A-DENV and C-DENV samples, peptides PM-22 and FPG-1 had the best-diagnostic performance with a sensitivity of 60 and 61.1%, and areas under the curve (AUC) of 0.7865 and 0.8131, respectively. A Random forest (RF) algorithm was used to select the best combination of peptides to classify DENV infection at a targeted specificity >80%. The best RF model for PM peptides that included A-DENV and C-DENV samples, reached a sensitivity of 72.3%, while for PG peptides, the best RF models for A-DENV only, C-DENV only and A-DENV + C-DENV reached a sensitivity of 88.9%, 89.1%, and 88.3%, respectively. In conclusion, the combination of multiple peptides constitutes a founding set of seromarkers for the discrimination of DENV infected individuals from other flavivirus infections.

Acute Response of Sclerostin to Whole-body Vibration with Blood Flow Restriction

Blood flow restriction may augment the skeletal response to whole-body vibration. This study used a randomised, crossover design to investigate the acute response of serum sclerostin and bone turnover biomarkers to whole-body vibration with blood flow restriction. Ten healthy males (mean±standard deviation; age: 27±8 years) completed two experimental conditions separated by 7 days: (i) whole-body vibration (10 1-minute bouts of whole-body vibration with 30 s recovery) or (ii) whole-body vibration with lower-body blood flow restriction (10 cycles of 110 mmHg inflation with 30 s deflation during recovery). Fasting blood samples were obtained immediately before and immediately after exercise, then 1 hour, and 24 hours after exercise. Serum samples were analysed for sclerostin, cross-linked C-terminal telopeptide of type I collagen, and bone-specific alkaline phosphatase. There was a significant time × condition interaction for bone-specific alkaline phosphatase (p=0.003); bone-specific alkaline phosphatase values at 24 hours post-exercise were significantly higher following whole-body vibration compared to combined whole-body vibration and blood flow restriction (p=0.028). No significant time × condition interaction occurred for any other outcome measure (p>0.05). These findings suggest that a single session of whole-body vibration combined with blood flow restriction does not significantly affect serum sclerostin or bone turnover biomarkers.

Effect of Vitamin E Supplement on Bone Turnover Markers in Postmenopausal Osteopenic Women: A Double-Blind, Randomized, Placebo-Controlled Trial

Vitamin E is a strong anti-oxidative stress agent that affects the bone remodeling process. This study evaluates the effect of mixed-tocopherol supplements on bone remodeling in postmenopausal osteopenic women. A double-blinded, randomized, placebo-controlled trial study was designed to measure the effect of mixed-tocopherol on the bone turnover marker after 12 weeks of supplementation. All 52 osteopenic postmenopausal women were enrolled and allocated into two groups. The intervention group received mixed-tocopherol 400 IU/day, while the control group received placebo tablets. Fifty-two participants completed 12 weeks of follow-up. Under an intention-to-treat analysis, vitamin E produced a significant difference in the mean bone resorption marker (serum C-terminal telopeptide of type I collagen (CTX)) compared with the placebo group (-0.003 ± 0.09 and 0.121 ± 0.15, respectively (p < 0.001)). In the placebo group, the CTX had increased by 35.3% at 12 weeks of supplementation versus baseline (p < 0.001), while, in the vitamin E group, there was no significant change of bone resorption marker (p < 0.898). In conclusion, vitamin E (mixed-tocopherol) supplementation in postmenopausal osteopenic women may have a preventive effect on bone loss through anti-resorptive activity.

4210 Da and 1866 Da polypeptides as potential biomarkers of liver disease progression in hepatitis B virus patients

HBV infection is recognized as a serious global health problem, and hepatitis B virus infection is a complicated chronic disease leading to liver cirrhosis (LC) and hepatocellular carcinoma (HCC). New biochemical serum markers could be used to advance the diagnosis and prognosis of HBV-associated liver diseases during the progression of chronic hepatitis B into cirrhosis and HCC. We determined whether the 4210 Da and 1866 Da polypeptides are serum metabolite biomarkers of hepatopathy with hepatitis B virus. A total of 570 subjects were divided into five groups: healthy controls, those with natural clearance, and patients with CHB, LC, and HCC. The 1866 Da and 4210 Da polypeptides were measured by Clin-ToF II MALDI-TOF-MS. There were significant differences in 4210 Da and 1866 Da levels among the five groups (P < 0.001). For the differential diagnosis of CHB from normal liver, the areas under the receiver operating characteristic (ROC) curve of 4210 Da and 1866 Da and their combination via logistic regression were 0.961, 0.849 and 0.967. For the differential diagnosis of LC from CHB, the areas under the ROC curve were 0.695, 0.841 and 0.826. For the differential diagnosis of HCC from CHB, the areas under the ROC curve were 0.744, 0.710 and 0.761, respectively. For the differential diagnosis of HCC from LC, the areas under the ROC curve of 4210 Da and 1866 Da were 0.580 and 0.654. The positive rate of 1866 Da was 45.5% and 69.0% in AFP-negative HCC patients and that of 4210 Da was 60.6% 58.6% in AFP-negative HCC patients of the study HCC vs. CHB and HCC vs. LC. The 4210 Da and 1866 Da polypeptide levels were positively correlated with HBV DNA levels (P < 0.001, r = 0.269; P < 0.001, r = 0.285). The 4210 Da and 1866 Da polypeptides had good diagnostic value for the occurrence and progression of HBV-related chronic hepatitis, liver cirrhosis and hepatocellular carcinoma and could serve to accurately guide treatment management and predict clinical outcomes.

Sclerostin and bone remodeling biomarkers responses to whole-body cryotherapy (- 110 °C) in healthy young men with different physical fitness levels

We investigated the effects of single and repeated exposures to whole-body cryotherapy on biomarkers of bone remodeling and osteo-immune crosstalk: sclerostin, osteocalcin (OC), C-terminal cross-linked telopeptide of type I collagen (CTx-I), osteoprotegerin (OPG) and free soluble receptor activator for nuclear factor κ B ligand (sRANKL). The study included 22 healthy males, grouped in high physical fitness level (HPhL) and low physical fitness level (LPhL), all undergone 10 consecutive sessions in a cryogenic chamber (- 110 °C). We observed a significant time-effect on sclerostin (p < 0.05), OC (p < 0.01), CTx-I (p < 0.001), OC/CTx-I (p < 0.05), and significant differences in sRANKL between the groups (p < 0.05) after the 1st cryostimulation; a significant time-effect on OC (p < 0.001) and OC/CTx-I (p < 0.001) after the 10th cryostimulation, and a significant time-effect on CTx-I (p < 0.001) and OC/CTx-I (p < 0.01) after 10 sessions of WBC. In conclusion, in young men, the first exposure to extreme cold induced significant changes in serum sclerostin. The changes in sRANKL, between groups, suggest that fitness level may modify the body's response to cold. The effects of the first stimulus and the whole session are not identical, probably due to the physiological development of habituation to cold.

Ibuprofen taken before exercise blunts the IL-6 response in older adults but does not alter bone alkaline phosphatase or c-telopeptide

INTRODUCTION

Non-steroidal anti-inflammatory drugs (NSAIDs) taken before exercise have been shown to impair bone formation. NSAIDs also suppress inflammatory cytokines, such as interleukin-6 (IL-6), that can have pro-resorptive effects. It is unclear how taking NSAIDs timed around exercise influences inflammatory and bone biomarkers following an acute exercise bout in older adults.

PURPOSE

To determine if timing of ibuprofen use relative to a single exercise bout has acute effects on serum IL-6, bone-specific alkaline phosphatase (BAP, marker of bone formation), and c-telopeptide of type I collagen (CTX, marker of bone resorption).

METHODS

As part of a 36-week exercise intervention, participants aged 60 to 75 years were randomized to 3 groups: placebo before and after exercise (PP), ibuprofen before and placebo after exercise (IP), or placebo before and ibuprofen after exercise (PI). Acute responses were studied in a subset of participants (12 PP, 17 IP, 13 PI). Blood was sampled before and immediately, 30 min, and 60 min after exercise for IL-6, BAP, and CTX.

RESULTS

The exercise-induced increase in IL-6 was blunted in response to IP when compared to PI 60-min after exercise (p < 0.001). There were no significant differences in the change in BAP or CTX between groups at any time points CONCLUSION: Ibuprofen taken before exercise dampened the inflammatory response to exercise but had no effects on bone biomarkers in older adults. It may be necessary to monitor changes for a longer time interval after an acute exercise bout to determine whether bone turnover is altered by ibuprofen or other NSAIDs.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00462722; Posted 04/19/2007.

GIP_HUMAN[22-51] is a new proatherogenic peptide identified by native plasma peptidomics

We recently established a new plasma peptidomic technique and comprehensively identified a large number of low-molecular weight and low-abundance native peptides using a single drop of human plasma. To discover a novel polypeptide that potently modulates the cardiovascular system, we performed a bioinformatics analysis of the large-scale identification results, sequentially synthesized the selected peptide sequences, tested their biological activities, and identified a 30-amino-acid proatherogenic peptide, GIP_HUMAN[22-51], as a potent proatherosclerotic peptide hormone. GIP_HUMAN[22-51] has a common precursor with the glucose-dependent insulinotropic polypeptide (GIP) and is located immediately N-terminal to GIP. Chronic infusion of GIP_HUMAN[22-51] into ApoE-/- mice accelerated the development of aortic atherosclerotic lesions, which were inhibited by co-infusions with an anti-GIP_HUMAN[22-51] antibody. GIP_HUMAN[22-51] increased the serum concentrations of many inflammatory and proatherogenic proteins, whereas neutralising antibodies reduced their levels. GIP_HUMAN[22-51] induced IκB-α degradation and nuclear translocation of NF-κB in human vascular endothelial cells and macrophages. Immunoreactive GIP_HUMAN[22-51] was detected in human tissues but there was no colocalization with the GIP. The plasma GIP_HUMAN[22-51] concentration in healthy humans determined using a stable-isotope tagged peptide was approximately 0.6 nM. This study discovered a novel endogenous proatherogenic peptide by using a human plasma native peptidomic resource.

Bisphosphonate use in children with cerebral palsy

BACKGROUND

Cerebral palsy (CP) is a heterogeneous group of non-progressive disorders of posture or movement, caused by a lesion of the developing brain. Osteoporosis is common in children with cerebral palsy, particularly in children with reduced gross motor function, and leads to an increased risk of fractures. Gross motor function in children with CP can be categorised using a tool called the Gross Motor Function Classification System (GMFCS). Bisphosphonate increases bone mineral density (BMD) and reduces fracture rates. Bisphosphonate is used widely in the treatment of adult osteoporosis. However, the use of bisphosphonate in children with CP remains controversial, due to a paucity of evidence and a lack of recent trials examining the efficacy and safety of bisphosphonate use in this population.

OBJECTIVES

To examine the efficacy and safety of bisphosphonate therapy in the treatment of low BMD or secondary osteoporosis (or both) in children with cerebral palsy (GMFCS Levels III to V) who are under 18 years of age.

SEARCH METHODS

In September 2020, we searched CENTRAL, MEDLINE, Embase, six other databases, and two trial registers for relevant studies. We also searched the reference lists of relevant systematic reviews, trials, and case studies identified by the search, and contacted the authors of relevant studies in an attempt to identify unpublished literature.

SELECTION CRITERIA

All relevant randomised controlled trials (RCTs), and quasi-RCTs, comparing at least one bisphosphonate (given at any dose, orally or intravenously) with placebo or no drug, for the treatment of low BMD or osteoporosis in children up to 18 years old, with cerebral palsy (GMFCS Levels III to V).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We were unable to conduct any meta-analyses due to insufficient data, and therefore provide a narrative assessment of the results.

MAIN RESULTS

We found two relevant RCTs (34 participants). Both studies included participants with non-ambulatory CP or CP and osteoporosis. Participants in both studies were similar in severity of CP, age distribution, and sex distribution. The two trials used different bisphosphonate medications and different intervention durations, but further comparison of the interventions was not possible due to a lack of published data from one trial. One trial received funding and support from research, academic, and hospital foundations, with pharmaceutical companies providing components of the calcium and vitamin supplement; the other trial did not report sources of funding. We judged one study at an overall high risk of bias; the other as overall unclear risk of bias.

PRIMARY OUTCOME

Compared to placebo or no treatment, both studies provided very low certainty evidence of improved BMD at least four months post-intervention in children treated with bisphosphonate. Only one study (12 participants) provided sufficient detail to assess a measure of the effect, and reported an improvement at six months post-intervention in lumbar spine z-score (mean difference (MD) 18%, 95% confidence interval (CI) 6.57 to 29.43; very low certainty evidence).

SECONDARY OUTCOMES

Very low certainty evidence from one study found that bisphosphonate reduced serum N-telopeptides (NTX) more than placebo; the other study reported that both bisphosphonate plus alfacalcidol and alfacalcidol alone reduced NTX, but did not compare groups. One study reported inconclusive results between groups for serum bone-specific alkaline phosphatase (BAP). The other study reported that both bisphosphonate plus alfacalcidol and alfacalcidol alone reduced BAP, but did not compare groups. Neither study reported data for the effect of bisphosphonate treatment on changes in volumetric BMD in the distal radius or tibia, changes in fracture frequency, bone pain, or quality of life. One study reported that two participants had febrile events noted during their first dosing schedule, but no further adverse events were reported in either relevant study.

AUTHORS' CONCLUSIONS

Based on the available evidence, there is very low certainty evidence that bisphosphonate treatment may improve bone health in children with cerebral palsy. We could only include one study with 14 participants in the assessment of the effect size; therefore, the precision of the effect estimate is low. We could only evaluate one planned primary outcome, as there was insufficient detail reported in the relevant studies. Further research from RCTs on the effect and safety of bisphosphonate to improve bone health in children with cerebral palsy is required. These studies should clarify the optimal standard treatment regarding weight-bearing exercises, vitamin D and calcium supplementation, and should include fracture frequency as a primary outcome.

Impact of metabolic syndrome and its components on bone remodeling in adolescents

INTRODUCTION

Osteoporosis and metabolic syndrome (MetS) are diseases that have serious public health consequences, reducing the quality of life of patients and increasing morbidity and mortality, with substantial healthcare expenditures.

OBJECTIVE

To evaluate the impact of MetS on bone mineral density (BMD) and biochemical markers of bone formation and resorption in adolescents with excess weight.

METHOD

A descriptive and analytical cross-sectional study was performed that evaluated 271 adolescents of both sexes (10 to 16 years). From the total sample, 42 adolescents with excess weight and the presence of MetS (14%) were selected. A further 42 adolescents with excess weight and without MetS were chosen, matched for chronological age, bone age, and pubertal developmental criteria to those with MetS, for each sex. Anthropometric measurements, blood pressure collection, and biochemical tests were performed in all adolescents, as well as evaluation of BMD and the bone biomarkers osteocalcin (OC), bone alkaline phosphatase (BAP), and carboxy-terminal telopeptide (S-CTx).

RESULTS

The adolescents with excess weight and MetS exhibited significantly lower transformed BMD and concentrations of BAP, OC, and S-CTx compared to the matched group, except for OC in boys. A negative and significant correlation was observed between total body BMD and BAP (r = -0.55568; p = 0.005), OC (r = -0.81760; p = < .000), and S-CTx (r = -0.53838; p = 0.011) in girls.

CONCLUSION

Metabolic syndrome may be associated with reduced bone mineral density and biochemical markers of bone formation and resorption in adolescents with excess weight.

One year of Football Fitness improves L1-L4 BMD, postural balance, and muscle strength in women treated for breast cancer

PURPOSE

To examine efficacy of 12 months Football Fitness offered twice per week on bone mineral density (BMD), bone turnover markers (BTM), postural balance, muscle strength, and body composition in women treated for early-stage breast cancer (BC).

METHODS

Women treated for early-stage BC were randomized to Football Fitness (FFG, n = 46) or control (CON, n = 22) in a 2:1 ratio for 12 months, with assessments performed at baseline, 6 months and 12 months. Outcomes were total body-, lumbar spine- and proximal femur BMD, total body lean and fat mass, leg muscle strength, postural balance, and plasma amino-terminal propeptide of type 1 procollagen (P1NP), osteocalcin, and C-terminal telopeptide of type 1 collagen (CTX). Intention-to-treat (ITT) analyses and per-protocol analyses (≥50% attendance in FFG) were performed using linear mixed models.

RESULTS

Participants in FFG completing the 12-month intervention (n = 33) attended 0.8 (SD = 0.4) sessions per week. Intention to treat analysis of mean changes over 12 months showed significant differences (p<.05) in L1-L4 BMD (0.029 g/cm2 , 95%CI: 0.001 to 0.057), leg press strength (7.2 kg, 95%CI: 0.1 to 14.3), and postural balance (-4.3 n need of support, 95%CI: -8.0 to -0.7) favoring FFG compared to CON. In the per-protocol analyses, L1-L4 and trochanter major BMD were improved (p = .012 and .030, respectively) in FFG compared with CON. No differences were observed between groups in BTMs in the ITT or per protocol analyses.

CONCLUSION

One year of Football Fitness training may improve L1-L4 BMD, leg muscle strength, and postural balance in women treated for early-stage breast cancer.

Prolyl Carboxypeptidase Mediates the C-Terminal Cleavage of (Pyr)-Apelin-13 in Human Umbilical Vein and Aortic Endothelial Cells

The aim of this study was to investigate the C-terminal cleavage of (pyr)-apelin-13 in human endothelial cells with respect to the role and subcellular location of prolyl carboxypeptidase (PRCP). Human umbilical vein and aortic endothelial cells, pre-treated with prolyl carboxypeptidase-inhibitor compound 8o and/or angiotensin converting enzyme 2 (ACE2)-inhibitor DX600, were incubated with (pyr)-apelin-13 for different time periods. Cleavage products of (pyr)-apelin-13 in the supernatant were identified by mass spectrometry. The subcellular location of PRCP was examined via immunocytochemistry. In addition, PRCP activity was measured in supernatants and cell lysates of LPS-, TNFα-, and IL-1β-stimulated cells. PRCP cleaved (pyr)-apelin-13 in human umbilical vein and aortic endothelial cells, while ACE2 only contributed to this cleavage in aortic endothelial cells. PRCP was found in endothelial cell lysosomes. Pro-inflammatory stimulation induced the secretion of PRCP in the extracellular environment of endothelial cells, while its intracellular level remained intact. In conclusion, PRCP, observed in endothelial lysosomes, is responsible for the C-terminal cleavage of (pyr)-apelin-13 in human umbilical vein endothelial cells, while in aortic endothelial cells ACE2 also contributes to this cleavage. These results pave the way to further elucidate the relevance of the C-terminal Phe of (pyr)-apelin-13.

Direct Measurement of ATP7B Peptides Is Highly Effective in the Diagnosis of Wilson Disease

BACKGROUND & AIMS

Both existing clinical criteria and genetic testing have significant limitations for the diagnosis of Wilson disease (WD), often creating ambiguities in patient identification and leading to delayed diagnosis and ineffective management. ATP7B protein concentration, indicated by direct measurement of surrogate peptides from patient dried blood spot samples, could provide primary evidence of WD. ATP7B concentrations were measured in patient samples from diverse backgrounds, diagnostic potential is determined, and results are compared with biochemical and genetic results from individual patients.

METHODS

Two hundred and sixty-four samples from biorepositories at 3 international and 2 domestic academic centers and 150 normal controls were obtained after Institutional Review Board approval. Genetically or clinically confirmed WD patients with a Leipzig score >3 and obligate heterozygote (carriers) from affected family members were included. ATP7B peptide measurements were made by immunoaffinity enrichment mass spectrometry.

RESULTS

Two ATP7B peptides were used to measure ATP7B protein concentration. Receiver operating characteristics curve analysis generates an area under the curve of 0.98. ATP7B peptide analysis of the sequence ATP7B 887 was found to have a sensitivity of 91.2%, specificity of 98.1%, positive predictive value of 98.0%, and a negative predictive value of 91.5%. In patients with normal ceruloplasmin concentrations (>20 mg/dL), 14 of 16 (87.5%) were ATP7B-deficient. In patients without clear genetic results, 94% were ATP7B-deficient.

CONCLUSIONS

Quantification of ATP7B peptide effectively identified WD patients in 92.1% of presented cases and reduced ambiguities resulting from ceruloplasmin and genetic analysis. Clarity is brought to patients with ambiguous genetic results, significantly aiding in noninvasive diagnosis. A proposed diagnostic score and algorithm incorporating ATP7B peptide concentrations can be rapidly diagnostic and supplemental to current Leipzig scoring systems.

Twice-weekly teriparatide improves lumbar spine BMD independent of pre-treatment BMD and bone turnover marker levels

INTRODUCTION

There have been no reports of the effects of baseline lumbar spine bone mineral density (LS-BMD) and bone turnover marker levels on the therapeutic effect of a 28.2-μg teriparatide formulation for twice-weekly use (2/W-TPTD).

MATERIALS AND METHODS

An analysis was performed using data from a double-blind, randomized, non-inferiority trial (TWICE study) conducted with patients who received 2/W-TPTD or a 56.5-μg teriparatide formulation for once-weekly use (1/W-TPTD) for 48 weeks. The patients were divided into tertile groups based on baseline LS-BMD, urinary type I collagen cross-linked N-telopeptide (u-NTX), and serum type I procollagen-N-propeptide (P1NP) levels, respectively. Time profiles of these measurements were analyzed. Furthermore, whether a change in P1NP is a predictor for percentage change in BMD was assessed.

RESULTS

Across all tertile groups divided based on baseline LS-BMD and levels of bone turnover markers, the LS-BMD increased significantly. The u-NTX level decreased throughout the study period in the high- and middle-u-NTX-level groups. The P1NP level increased after 4 weeks, but subsequently decreased after 12 weeks and thereafter in the high-P1NP-level group; it increased after 4 weeks and subsequently fluctuated near the baseline level in the middle-P1NP-level group. A cut-off value of 12.0 µg/L for change in P1NP after 4 weeks of 2/W-TPTD as a predictor for percentage change in LS-BMD of 3% or more after 48 weeks gave a positive predictive value of 89.6%.

CONCLUSION

2/W-TPTD, just like 1/W-TPTD, improved LS-BMD significantly, regardless of baseline LS-BMD and bone turnover marker levels.

Serum N-terminal telopeptide of type I collagen as a biomarker for predicting bone density loss in patients with Crohn disease

Background

The serum N-terminal telopeptide of type I collagen (NTx) is significantly higher in patients with Crohn disease (CD) than in healthy individuals and patients with ulcerative colitis. This study aimed to investigate whether an elevated serum NTx level is a risk predictor of osteoporosis in patients with CD.

Methods

Based on whether the femoral Z-score decreased over a 2-year period, 41 CD patients were divided into the ΔZ-score <0 group (Z-score decreased) and the ΔZ-score ≥0 group (Z-score did not decrease). The risk predictors of a femoral Z-score decrease were examined. Furthermore, we investigated the correlations between the ΔZ-score (which represents the change in the Z-score over a 2-year period) and the mean levels of biomarkers, including the Crohn Disease Activity Index (CDAI), serum albumin, C-reactive protein, and bone metabolism markers (including NTx) measured initially (i.e., in our previous study) and 2 years later (present study). The relationships between anti-tumor necrosis factor α (anti-TNF-α) therapy and serum NTx levels were also examined.

Results

Although there was no correlation between the mean CDAI and the ΔZ-score, the mean serum NTx and albumin levels were significantly correlated with the ΔZ-score (P<0.01 and P = 0.02, respectively). Furthermore, the femoral Z-score tended to be lower in the anti-TNF-α administration group than in the non-administration group.

Conclusions

These observations indicated that an elevated serum NTx could be a useful marker for predicting a decrease in the femoral bone mineral density in CD patients. Anti-TNF-α therapy maintained an elevated serum NTx level, suggesting that treatment with anti-TNF-α may help control increased bone resorption in CD patients.

Rapid Detection of COVID-19 Using MALDI-TOF-Based Serum Peptidome Profiling

The outbreak of coronavirus disease 2019 (COVID-19) caused by SARS CoV-2 is ongoing and a serious threat to global public health. It is essential to detect the disease quickly and immediately to isolate the infected individuals. Nevertheless, the current widely used PCR and immunoassay-based methods suffer from false negative results and delays in diagnosis. Herein, a high-throughput serum peptidome profiling method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is developed for efficient detection of COVID-19. We analyzed the serum samples from 146 COVID-19 patients and 152 control cases (including 73 non-COVID-19 patients with similar clinical symptoms, 33 tuberculosis patients, and 46 healthy individuals). After MS data processing and feature selection, eight machine learning methods were used to build classification models. A logistic regression machine learning model with 25 feature peaks achieved the highest accuracy (99%), with sensitivity of 98% and specificity of 100%, for the detection of COVID-19. This result demonstrated a great potential of the method for screening, routine surveillance, and diagnosis of COVID-19 in large populations, which is an important part of the pandemic control.

The use of bone turnover markers for monitoring the treatment of osteoporosis in postmenopausal females undergoing total knee arthroplasty: a prospective randomized study

BACKGROUND

Osteoporosis (OP) and osteoarthritis (OA) commonly coexist in postmenopausal females. The decrease in bone density and increase in bone resorption in postmenopausal females with OP may consequently affect the surgical outcome of total knee arthroplasty (TKA). However, clinicians often ignore monitoring the treatment of OP in the perioperative management of TKA. Bone turnover marker (BTM) can timely and accurately reflect bone metabolism to monitor the treatment of OP. The purpose of this study was to investigate the effect of BTM monitoring to guide the treatment of OP in postmenopausal females undergoing TKA.

METHODS

Postmenopausal females with OP who underwent primary unilateral TKA were randomly divided into two groups (monitoring group and control group), given oral medication (alendronate, calcitriol, and calcium), and followed for 1 year. In the monitoring group, serum BTMs (C-telopeptide of type I collagen (CTX-I), N-terminal propeptide of type I procollagen (PINP), and 25(OH)D) were assessed preoperatively and repeated postoperatively; alendronate was withdrawn when CTX-I and PINP reached the reference interval; and calcitriol and calcium were withdrawn when 25(OH)D reached the reference interval. In the control group, oral medication was implemented for a uniform duration of 3 months. During the 1-year follow-up, the mean maximum total point motion (MTPM) of the tibial component, bone mineral density (BMD), visual analog scale (VAS) score, range of motion, and Oxford Knee Score (OKS) score were obtained.

RESULTS

In the monitoring group, BTM monitoring prolonged the medication duration, but did not cause more adverse reactions than in the control group. The mean MTPM values at 6 m and 12 m in the monitoring group were lower than those in the control group, and the BMD at 12 m in the monitoring group was significantly higher than that in the control group. Patients in the monitoring group had lower VAS scores at 6 m and higher OKS scores at 6 m and 12 m than those in the control group.

CONCLUSION

In postmenopausal females with osteoporosis undergoing primary TKA, the application of BTM monitoring to guide the treatment of osteoporosis can enhance bone density, maintain prosthesis stability, and improve surgical outcome.

TRIAL REGISTRATION

ChiCTR ChiCTR-INR-17010495 . Registered on 22 January 2017.

Comprehensive Quantification of Carboxymethyllysine-Modified Peptides in Human Plasma

A prolonged hyperglycemic condition in diabetes mellitus results in glycation of plasma proteins. N(ε)-Carboxymethyllysine (CML) is a well-known protein advanced glycation end product, and one of its mechanisms of formation is through further oxidation of Amadori compound modified lysine (AML). Unlike enrichment of AML peptides using boronate affinity, biochemical enrichment methods are scarce for comprehensive profiling of CML-modified peptides. To address this problem, we used AML peptide sequence and site of modification as template library to identify and quantify CML peptides. In this study, a parallel reaction monitoring workflow was developed to comprehensively quantify CML modified peptides in Type 1 diabetic subjects' plasma with good and poor glycemic control (n = 20 each). A total of 58 CML modified peptides were quantified, which represented 57 CML modification sites in 19 different proteins. Out of the 58 peptides, five were significantly higher in poor glycemic control samples with the area under the receiver operating characteristic curve ≥0.83. These peptides could serve as promising indicators of glycemic control in Type 1 diabetes management.

Changes of bone turnover markers after elderly hip fracture surgery

INTRODUCTION

Bone turnover markers (BTMs) can be used to monitor bone metabolism, while the actual clinical changing in hip fracture had not been certified to evaluate the changes of BTMs during the healing process after surgery of elderly hip fractures; and to get the effects of operation type, gender, serum 25(OH)D level, and age on bone turnover markers.

MATERIALS AND METHODS

A total of 100 elderly cases with hip fracture were selected, including 74 females and 26 males, and the patients were followed to 180-230 days after surgery. Serum levels of N-propeptide of type 1 collagen (P1NP), C-terminal crosslinking telopeptides of type 1 collagen (CTX), Osteocalcin (OC), and 25 hydroxy vitamin D (25OHD) were investigated. Bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry (DXA).

RESULTS

(1) P1NP and CTX showed peak time at 30-60 days after operation, while OC keep going even at 180-230 days; P1NP showed less than 4 times elevation during healing, CTX and OC only had less than 2 times rise. (2) Female had higher serum CTX and OC than male, intramedullary nailing for intertrochanteric fracture patients had higher P1NP than hip replacement for femoral neck fracture patients, and both the degrees of increase were less than 50%. (3) Serum average 25(OH)D level had no effect on BTMs during the fracture healing; different from the young old (65-84 years), serum OC level of eldest older patients(≥ 85 years) decreased early in the process of fracture healing.

CONCLUSIONS

BTMs reached the peak level in 30-60 days after surgery, P1NP showed less than 4 times elevation, and CTX and OC had less than 2 times rise. It was not necessary to take gender into account when observing P1NP, and it was not necessary to take fracture and operation type into account when observing CTX and OC.

Sclerostin, preadipocyte factor-1 and bone mineral values in eumenorrheic adolescent athletes with different training patterns

INTRODUCTION

The specific aims of the study were to compare possible differences in sclerostin and preadipocyte factor-1 (Pref-1) between rhythmic gymnasts (RG), swimmers (SW) and untrained controls (UC), and to investigate the relationships of sclerostin and Pref-1 with bone mineral characteristics in studied groups.

MATERIALS AND METHODS

This study included 62 eumenorrheic adolescents (RG = 22; SW = 20; UC = 20). Bone mineral and body composition characteristics were measured by dual-energy X-ray absorptiometry, and sclerostin, Pref-1, osteocalcin and C-terminal telopeptide of type I collagen (CTx) were measured.

RESULTS

Sclerostin was higher (P = 0.001) in RG (129.35 ± 51.01 pg/ml; by 74%) and SW (118.05 ± 40.05 pg/ml; by 59%) in comparison with UC (74.32 ± 45.41 pg/ml), while no differences (P = 0.896) were seen in Pref-1 (RG: 1.42 ± 0.16 ng/ml; SW: 1.41 ± 0.20 ng/ml; UC: 1.39 ± 0.26 ng/ml) between groups. Osteocalcin (RG: 7.74 ± 4.09 ng/ml; SW: 8.05 ± 4.18 ng/ml; UC: 7.04 ± 3.92 ng/ml; P = 0.843) and CTx (RG: 0.73 ± 0.22 ng/ml; SW: 0.64 ± 0.16 ng/ml; UC: 0.62 ± 0.20 ng/ml; P = 0.173) were not different between groups. Sclerostin correlated (P < 0.05) with whole-body bone mineral content (r = 0.61) and lumbar spine (LS) areal bone mineral density (aBMD) (r = 0.43) in RG, and femoral neck aBMD (r = 0.45) in UC. No correlation was found between sclerostin and bone mineral values in SW, and Pref-1 was not correlated with any bone mineral characteristics in studied groups. Sclerostin was the independent variable that explained 14% of the total variance (R² × 100) in LS aBMD value only in RG.

CONCLUSIONS

Adolescent athletes have higher sclerostin compared to UC. Sclerostin was correlated with bone mineral values and predicted areal bone mineral density in RG.

Umbilical cord N-terminal procollagen of type l collagen (P1NP) and beta C-terminal telopeptide (βCTX) levels in term pregnancies with vitamin D deficiency

AIMS

The aim of the present study was to evaluate umbilical cord N-terminal procollagen of type l collagen (P1NP) and beta C-terminal telopeptide (βCTX) levels in term pregnancies with vitamin D deficiency.

MATERIALS AND METHODS

Ninety-two pregnant women between 19 and 35-years-old who delivered at term gestational age were included in the study and divided into deficient (n = 32), insufficient (n = 30), and normal (control) vitamin D levels (n = 30).

RESULTS

Maternal demographic characteristics and biochemical parameters were similar among groups. The mean umbilical cord P1NP level was 221.4 (211.7-231.0, 95%CI) pg/mL in the vitamin D deficiency group, 282.5 (271.2-293.8, 95%CI) pg/mL in the vitamin D insufficiency group, and 280.9 (270.9-290.8, 95%CI) pg/mL in the control group and significantly lower in vitamin D deficiency group than others (p < .001). Umbilical cord P1NP level was similar in the vitamin D insufficiency group and control group (p = .971). The mean umbilical cord βCTX level was 5530, 9 (5511.5-5550.3, 95%CI) pg/mL in the vitamin D deficiency group, 5516.3 (5498.4-5534.2, 95%CI) pg/mL in the vitamin D insufficiency group, and 5510 (5491.4-5528.5, 95%CI) pg/mL in the control group, which was statistically similar among the groups (p = .251).

CONCLUSION

Our results indicated that vitamin D deficiency during pregnancy affects fetal bone osteoblast activity.

Elevated Urate Levels Do Not Alter Bone Turnover Markers: Randomized Controlled Trial of Inosine Supplementation in Postmenopausal Women

OBJECTIVE

Observational studies have consistently demonstrated that serum urate level positively correlates with bone mineral density (BMD). We undertook this study to determine whether moderate hyperuricemia induced by inosine supplements influences bone turnover markers in postmenopausal women over a 6-month period.

METHODS

One hundred twenty postmenopausal women were recruited for a 6-month randomized, double-blind, placebo-controlled trial. Key exclusion criteria were osteoporosis, previous fragility fracture, bisphosphonate therapy, gout, kidney stones, and a urine pH level of ≤5.0. Participants were randomized in a 1:1 ratio to receive placebo or inosine. The coprimary end points were change in levels of N-propeptide of type I procollagen (PINP) and change in levels of β-C-telopeptide of type I collagen (β-CTX). Change in BMD, as measured by dual x-ray absorptiometry, was an exploratory end point.

RESULTS

Administration of inosine led to a significant increase in serum urate concentration over the study period (P < 0.0001 for all follow-up time points). At week 26, the mean change in serum urate concentration was +0.13 mmoles/liter (+2.2 mg/dl) in the inosine group and 0.00 mmoles/liter (0 mg/dl) in the placebo group. There was no difference in PINP or β-CTX levels between groups over the 6 months. There were no significant changes in bone density between groups over the 6 months. Adverse events and serious adverse events were similar between the 2 groups.

CONCLUSION

This clinical trial shows that although inosine supplementation leads to sustained increases in serum urate levels over a 6-month period, it does not alter markers of bone turnover in postmenopausal women. These findings do not support the concept that urate has direct biologic effects on bone turnover.

Low serum levels of bone turnover markers are associated with the presence and severity of diabetic retinopathy in patients with type 2 diabetes mellitus

BACKGROUND

Accumulating evidence demonstrates an association of type 2 diabetes mellitus (T2DM) and its microvascular complications with increased fracture risk. In this study, we aimed to evaluate the relationships between serum concentrations of bone turnover markers and the presence and/or severity of diabetic retinopathy (DR) among patients with T2DM.

METHODS

A total of 285 patients with T2DM comprising 168 patients without DR and 117 patients with DR were enrolled in the cross-sectional study. In the latter group, patients were further divided into patients of mild and severe DR stages. The biochemical parameters and bone turnover markers were determined in all participants.

RESULTS

This study found that serum levels of procollagen type 1 N-terminal propeptide (P1NP), a bone formation marker, and the bone resorption marker serum β-cross-linked C-telopeptide of type I collagen (β-CTX) were more decreased in diabetic patients with DR than in those without DR, with differences remaining significant (P < .05) in multivariate linear regression models after adjustments for multiple confounding factors. Osteocalcin and β-CTX levels were further reduced along with the severity of DR among participants with DR. Moreover, multivariate logistic regression analysis revealed that lower serum levels of P1NP and β-CTX were associated with higher odds for the presence of DR, while β-CTX was associated with the severity of DR.

CONCLUSION

Our results suggest that the development of DR might be involved in the progression of T2DM-induced deficits in bone formation and resorption or vice versa. Follow-up studies and further research are necessary to validate the associations and elucidate the underlying mechanisms.

Effectiveness of electroacupuncture as a treatment for osteoporosis: A systematic review and meta-analysis

BACKGROUND

Osteoporosis (OP) results in an increased risk of fragility fractures, representing a major public health problem. In preventing OP, complementary and alternative medicine, such as acupuncture, was recommended because of the low efficiency and side effects of medications. Recently, there is insufficient evidence on electroacupuncture as an effective therapy for OP management. Hence, we evaluated the effectiveness of electroacupuncture for OP treatment.

METHODS

We conducted a systematic review and meta-analysis of clinical studies on patients with OP. Five databases (PubMed, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang) were searched from the earliest publication date to March 12, 2020. Randomized controlled trials (RCTs) were included if electroacupuncture was applied as the sole treatment or as an adjunct to other treatments compared with medications in patients with OP. The measurement outcomes included serum aminoterminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX) levels, bone mineral density (BMD) of lumbar, and visual analog scale scores for OP-related pain. Acupoints were extracted when available.

RESULTS

In total, 11 RCTs involving 731 participants were included for further meta-analysis. The meta-analysis showed that the use of electroacupuncture as a sole treatment or as an adjunct to other treatments could relieve OP-related pain compared with medications [mean difference (MD) =  -0.58, 95% confidence interval (CI); MD =  -0.97 to -0.19, P = .003, I2 = 88%; MD =  -1.47, 95% CI = -2.14 to -0.79, P < .001, I2 = 96%). Meanwhile, the results showed a favorable effect of electroacupuncture on decreasing serum beta-CTX levels. However, there were no significant differences in serum PINP levels and BMD of lumbar. Shenshu (BL23) was the most frequent acupoint stimulation among these studies.

CONCLUSIONS

The application of electroacupuncture as an independent therapy or as an adjunct to other treatments might attenuate OP-related pain and serum beta-CTX levels. However, to overcome the methodological shortcomings of the existing evidence, due to a small size of samples and high risk of bias in these included RCTs, further rigorous studies are required.

Dimethandrolone Undecanoate, a Novel, Nonaromatizable Androgen, Increases P1NP in Healthy Men Over 28 Days

CONTEXT

Dimethandrolone undecanoate (DMAU) is being developed as a male contraceptive. Daily oral administration of DMAU, a potent androgen that is not aromatized, markedly suppresses serum testosterone (T) and estradiol (E2) in healthy men. E2 deficiency can increase bone resorption in men.

OBJECTIVE

This work aimed to assess changes in bone turnover markers with DMAU administration in a 28-day study.

DESIGN

A randomized, double-blind, placebo-controlled study was conducted.

SETTING

This study took place at 2 academic medical centers.

PARTICIPANTS

Healthy men, age 18 to50 years (n = 81), participated.

INTERVENTION

Men received 0, 100, 200, or 400 mg of oral DMAU for 28 days. Serum C-terminal telopeptide of type I collagen (CTX; bone resorption marker) and procollagen type I amino-terminal propeptide (P1NP; bone formation marker) were measured on days 1 and 28.

MAIN OUTCOME MEASURES

Changes in bone turnover markers and serum hormones over the treatment period were measured.

RESULTS

On day 28, median serum T and E2 were markedly suppressed in all treatment groups vs placebo (P < .001 for both). Percentage change (%) in serum P1NP significantly differed across treatment groups (P = .007): Serum P1NP significantly increased in the 200 mg (5%, interquartile range [IQR] -7% to 27%) and 400 mg (22%, IQR -1% to 40%) groups relative to placebo (-8%, IQR -20% to 0%). Change (%) in serum CTX did not differ between groups (P = .09).

CONCLUSIONS

DMAU administration for 28 days to healthy men leads to marked suppression of serum T and E2, yet increases P1NP, a serum marker of bone formation. Longer-term studies of the potent androgen DMAU are warranted to determine its impact on bone health in men.

Exploratory Analysis in the Differences in Blood Serum and Seminal Plasma of Adipose-Tissue Related Peptides in Obese and Non-Obese Men and Their Correlations With Semen Parameters

OBJECTIVES

Evaluating the relationship between circulating metabolic biomarkers and semen parameters in obese, overweight and normal-weight patients.

METHODS

Patients were recruited at the "Andrology and Pathophysiology of Reproduction Unit", in Santa Maria Goretti Hospital. Divided into three groups were 98 participants (obese, overweight and normal-weight patients) according to BMI and were analyzed for three adipokines and six hormone peptides in blood serum and seminal plasma using Luminex assay. Standard semen analysis was performed for ejaculate volume, sperm concentration, total sperm count, motility, morphology and leukocytes.

RESULTS

In all groups of subjects, we observed a higher concentration of blood serum c-peptide, GIP, PAI-1, leptin, ghrelin and GLP-1 in comparison to seminal plasma; differently, higher levels in seminal plasma were observed for insulin and visfatin. In comparison to the non-obese subjects, obese subjects showed a higher blood serum concentration of c-peptide, GLP-1, GIP and leptin and a higher concentration of seminal plasma of GIP and insulin. Total sperm count, progressive motility, motility, and atypical forms directly correlated with PAI-1 and visfatin, whereas GLP-1 directly correlated only with total progressive motility.

CONCLUSION

Obese men showed a different pattern of blood serum and seminal plasma adipokines and hormone peptides concentrations in comparison to normal-weight men. Furthermore, these molecules correlated with functional seminal parameters. Our findings support the option to consider these molecules as new biomarkers and pharmacological targets for a new therapeutic approach in male infertility. However, further studies identifying other potential biomarkers of male infertility with important clinical implication and characterizing their mechanisms of action are mandatory.

Association of Bone Metabolism Indices and Bone Mineral Density with Diabetic Retinopathy in Elderly Patients with Type 2 Diabetes Mellitus: A Cross-Sectional Inpatient Study in China

OBJECTIVE

This study is aimed at analyzing the association between bone metabolism indices and diabetic retinopathy (DR) in elderly patients with type 2 diabetes mellitus.

METHODS

Data of 352 men and 284 postmenopausal women, aged more than 50 years, with type 2 diabetes mellitus were retrospectively analyzed. Patients were divided into three groups based on the degree of DR: nondiabetic retinopathy (NDR) group, background diabetic retinopathy (BDR) group, and proliferative diabetic retinopathy (PDR) group.

RESULTS

(1) The diabetic duration and urinary albumin to creatinine ratio (UACR) were significantly higher in the PDR and BDR groups than in the NDR group (P < 0.05). The level of beta-C-terminal telopeptide (β-CTX) in male patients was lower in the PDR and BDR groups than in the NDR group (P < 0.05). In addition, the level of procollagen 1 intact N-terminal (P1NP) in female patients was higher in the PDR and BDR groups than in the NDR group (P < 0.05). (2) For men and postmenopausal women, the proportion of vitamin deficiency was higher in the PDR and BDR groups than in the NDR group (P < 0.05). (3) The logistic regression analysis in men and postmenopausal women showed that the diabetic duration and lower levels of UACR and 25(OH)D were independent risk factors for DR (P < 0.05). (4) The diabetic duration was also an independent risk factor for PDR (P < 0.05); however, no independent correlation was found between the level of 25(OH)D and PDR (P > 0.05).

CONCLUSIONS

A close association was observed between 25(OH)D level and DR in the elderly male patients and postmenopausal women with type 2 diabetes mellitus. P1NP and β-CTX levels might be closely related to DR in elderly male patients and postmenopausal women with type 2 diabetes mellitus.

Matrix-assisted ionization mass spectrometry in targeted protein analysis - An initial evaluation

RATIONALE

Matrix-assisted ionization (MAI) is a relatively new ionization technique for analysis by mass spectrometry (MS). The technique is simple and has been shown to be less influenced by matrix effects than e.g. electrospray ionization (ESI). These features are of interest in the targeted analysis of proteins from biological samples.

METHODS

Targeted protein determination by MAI-MS was evaluated using a triple quadrupole mass analyzer equipped with a stripped nanoESI source in selected reaction monitoring (SRM) mode. The proteins were analyzed using the bottom-up approach with stable isotopic labeled peptides as internal standards (IS). The MAI matrix was 3-nitrobenzonitrile dissolved in acetonitrile. Aqueous sample and matrix solution were mixed in a 1:3 volume ratio. One microlitre of the dried matrix/analyte sample was introduced into the inlet of the mass spectrometer where ionization commences.

RESULTS

SRM settings established for ESI-SRM-MS of the peptides here investigated were applicable in MAI-SRM-MS for all evaluated peptides except one that is poorly soluble in water. Addition of IS provided efficient correction at most levels (relative standard deviation (RSD) ≤28% (except lowest digest level), r²  ≥ 0.995). This was also true for the more complex biological matrices, diluted urine (1:1; RSD = 20% a synthetic peptide, NLLGLIEAK) and diluted digested serum (1:100; RSD = 7% digested cytochrome C). Biological matrix influenced the signal intensity unless sufficiently diluted.

CONCLUSIONS

The results demonstrate that MAI-SRM-MS has promising potential in targeted protein determination by the bottom-up approach because of its simplicity, ease of use, and speed. However, more data is needed to confirm the results prior to application in a clinical setting.

Association of Insulin Resistance and β-cell Function With Bone Turnover Biomarkers in Dysglycemia Patients

BACKGROUND

The interrelation between glucose and bone metabolism is complex and has not been fully revealed. This study aimed to investigate the association between insulin resistance, β-cell function and bone turnover biomarker levels among participants with abnormal glycometabolism.

METHODS

A total of 5277 subjects were involved through a cross-sectional study (METAL study, http://www.chictr.org.cn, ChiCTR1800017573) in Shanghai, China. Homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell dysfunction (HOMA-%β) were applied to elucidate the nexus between β-C-terminal telopeptide (β-CTX), intact N-terminal propeptide of type I collagen (P1NP) and osteocalcin (OC). β-CTX, OC and P1NP were detected by chemiluminescence.

RESULTS

HOMA-IR was negatively associated with β-CTX, P1NP and OC (regression coefficient (β) -0.044 (-0.053, -0.035), Q4vsQ1; β -7.340 (-9.130, -5.550), Q4vsQ1 and β -2.885 (-3.357, -2.412), Q4vsQ1, respectively, all P for trend <0.001). HOMA-%β was positively associated with β-CTX, P1NP and OC (β 0.022 (0.014, 0.031), Q4vsQ1; β 6.951 (5.300, 8.602), Q4vsQ1 and β 1.361 (0.921, 1.800), Q4vsQ1, respectively, all P for trend <0.001).

CONCLUSIONS

Our results support that lower bone turnover biomarker (β-CTX, P1NP and OC) levels were associated with a combination of higher prevalence of insulin resistance and worse β-cell function among dysglycemia patients. It is feasible to detect bone turnover in diabetes or hyperglycemia patients to predict the risk of osteoporosis and fracture, relieve patients' pain and reduce the expenses of long-term cure.

New Markers of Bone Fragility in Hemodialysis Patients: A Monocentric Study

INTRODUCTION

Mechanisms underlying bone fragility in patients under dialysis are various. The assessment of bone disorder is not yet codified in these patients. Our study aimed to determine the relationship between the serum fibroblast growth factor 23 (FGF23) level and bone fragility. We also aimed to assess the bone alkaline phosphatase (bAP) to the C-terminal telopeptide of type I (CTX) ratio and the FGF23*bAP product to CTX ratio in patients under hemodialysis.

METHODOLOGY

We conducted a cross-sectional study, including 76 patients under hemodialysis. To assess bone fragility, we measured bAP, CTX, and FGF 23. We calculated the bAP to the CTX ratio (bAP/CTX) and the FGF23*bAP product to the CTX ratio (FGF23*bAP/CTX). We defined bone fragility as the existence of osteoporosis or fragility fractures. Receiver operating characteristic (ROC) curves were evaluated for each biological using the existence of osteoporosis or fragility fracture as the gold standard for bone fragility.

RESULTS

There were 51 men. The mean age was 53.36 ± 14.27 years. Bone fragility was noted in 25 cases. Patients with osteoporosis had higher FGF*bAP/CTX and bAP/CTX ratios. The ability of the ratio (bAP/CTX) to distinguish patients with osteoporosis from those without osteoporosis was good, with a ROC AUC of 0.707. The optimal ratio cut-off value with the highest accuracy was 9.72. The ability of the ratio (FGF23*bAP/CTX) to distinguish patients with bone fragility was good, with a ROC AUC of 0.701. The optimal ratio cut-off value with the highest accuracy was 1621.89 (sensitivity 60%, specificity 78.4%).

CONCLUSION

Our study showed FGF23, FGF23*bAP product to CTX ratio, and the bAP to CTX ratio can be used as markers of bone fragility in hemodialysis patients. Therefore, these noninvasive and relatively inexpensive methods may serve to diagnose bone fragility in patients under hemodialysis.

Reliable and generic liquid chromatography/mass spectrometry quantification of short peptides using a stable-isotope-labeled labeling agent

RATIONALE

It is important to investigate the behavior of protein hydrolysate components in both in vitro and in vivo studies, to support the elucidation of their biological functions. As protein hydrolysates and biological matrices are highly complex mixtures, it is essential to apply fully reliable and flexible analytical approaches.

METHODS

A novel and generic Liquid Chromatography/Mass Spectrometry methodology was developed to analyze short peptides. A stable-isotope-labeled labeling agent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (¹³ C₃ ) was synthesized and used to prepare internal standards from non-labeled analyte peptides. The amino acid and peptides p, pG, Pp, GPp and PpG (where p stands for hydroxyproline) were used for proof of principle.

RESULTS

The method showed acceptable performance in solvent, in simulated gastrointestinal fluid and in serum. The (linear) dynamic range expanded to over four orders of magnitude, which is very useful when multiple analytes are analyzed in a biological matrix, due to the large differences in concentrations observed for endogenous and protein hydrolysate components. The method provides absolute-quantitative results and is fully accountable on the single-sample and single-component level.

CONCLUSIONS

The methodology can be applied to reliably quantify protein hydrolysate nutraceutical components at various stages during their in vivo processing. Internal standards can also be synthesized for other short peptides whenever they are expected to have biological relevance and require quantification. Overall this provides an excellent analytical tool to support the elucidation of the biological functions of protein hydrolysate components.

Association between osteoporosis and hepatitis B cirrhosis: a case-control study

Background and aims

Hepatitis B virus (HBV)-related cirrhosis is associated with decreased bone mineral density (BMD); however, the mechanism is yet unknown. To assess the incidence of osteoporosis in patients with HBV-associated cirrhosis and relevant mechanisms.

Methods

A total of 80 hospitalized patients with HBV-associated cirrhosis and 80 healthy controls were enrolled. The levels of serum osteocalcin, total procollagen type 1 amino-terminal propeptide, β-C-terminal telopeptide of type I collagen (β-CTX), and 25-hydroxy vitamin D3 (25(OH)D3) was evaluated in the cirrhosis group.

Results

The BMDs of the lumbar spine (P<0.001) and hip joints (P=0.015) in the cirrhosis group were significantly lower than those in the controls. The incidence of osteoporosis in the cirrhosis group was significantly higher than that in the control group (P<0.001). Compared to the patients of the Child-Pugh grade A and B, the BMD of lumbar spine and 25(OH)D3 was significantly decreased in patients of grade C, while β-CTX was elevated. Patients in the cirrhosis group faced a higher risk of osteoporosis as compared to the controls(P<0.001).

Conclusions

Enhanced bone resorption accounted for increased risk of osteoporosis in severe cirrhosis. Thus, HBV-associated cirrhosis was a risk factor for osteoporosis.

Metabolomic Associations with Serum Bone Turnover Markers

Bone is a dynamic tissue that is in a constant state of remodeling. Bone turnover markers (BTMs), procollagen type I N-terminal propeptide (P1NP) and C-terminal telopeptides of type I collagen (CTX), provide sensitive measures of bone formation and resorption, respectively. This study used ultra-high-resolution metabolomics (HRM) to determine plasma metabolic pathways and targeted metabolites related to the markers of bone resorption and formation in adults. This cross-sectional clinical study included 34 adults (19 females, mean 27.8 years), without reported illnesses, recruited from a US metropolitan area. Serum BTM levels were quantified by an ELISA. Plasma HRM utilized dual-column liquid chromatography and mass spectrometry to identify metabolites and metabolic pathways associated with BTMs. Metabolites significantly associated with P1NP (p < 0.05) were significantly enriched in pathways linked to the TCA cycle, pyruvate metabolism, and metabolism of B vitamins important for energy production (e.g., niacin, thiamin). Other nutrition-related metabolic pathways associated with P1NP were amino acid (proline, arginine, glutamate) and vitamin C metabolism, which are important for collagen formation. Metabolites associated with CTX levels (p < 0.05) were enriched within lipid and fatty acid beta-oxidation metabolic pathways, as well as fat-soluble micronutrient pathways including, vitamin D metabolism, vitamin E metabolism, and bile acid biosynthesis. P1NP and CTX were significantly related to microbiome-related metabolites (p < 0.05). Macronutrient-related pathways including lipid, carbohydrate, and amino acid metabolism, as well as several gut microbiome-derived metabolites were significantly related to BTMs. Future research should compare metabolism BTMs relationships reported here to aging and clinical populations to inform targeted therapeutic interventions.

Mass spectrometric characterisation of the circulating peptidome following oral glucose ingestion in control and gastrectomised patients

RATIONALE

Meal ingestion triggers secretion of a variety of gut and endocrine peptides important in diabetes research which are routinely measured by immunoassays. However, similarities between some peptides (glucagon, oxyntomodulin and glicentin) can cause specificity issues with immunoassays. We used a liquid chromatography/tandem mass spectrometry (LC/MS/MS) methodology to unambiguously monitor multiple gut peptides in human plasma.

METHODS

A simple acetonitrile-based protein precipitation step, followed by evaporation and solid-phase extraction, removed high-abundance proteins from samples prior to nano-LC/MS/MS analysis on an Orbitrap Q-Exactive Plus mass spectrometer using a data-dependent methodology. Database searching using PEAKS identified multiple gut-derived peptides, including peptides in the mid-pg/mL range. The relative levels of these and previously characterised peptides were assessed in plasma samples from gastrectomised and control subjects during an oral glucose tolerance test.

RESULTS

Analysis of plasma extracts revealed significantly elevated levels of a number of peptides following glucose ingestion in subjects who had undergone gastrectomy compared with controls. These included GLP-1(7-36), GLP-1(9-36), glicentin, oxyntomodulin, GIP(1-42), GIP(3-42), PYY(1-36), PYY(3-36), neurotensin, insulin and C-peptide. Motilin levels decreased following glucose ingestion. Results showed good correlation with immunoassay-derived concentrations of some peptides in the same samples. The gastrectomy group also had higher, but non-glucose-dependent, circulating levels of peptides from PIGR and DMBT1.

CONCLUSIONS

Overall, the approach showed that a fast, generic and reproducible LC/MS/MS methodology requiring only a small volume of plasma was capable of the multiplexed detection of a variety of diabetes-related peptides.

Pharmacokinetics and Transport of an Osteogenic Dodecapeptide

A dodecapeptide with the amino acid sequence of IEELEEELEAER (PIE), identified from Mytilus edulis proteolysis hydrolysates, has shown good bone-forming activity in previous studies. The pharmacokinetics and transport of the PIE peptide in vivo or in vitro were investigated in this study. The results showed that the PIE peptide can be transported into monolayer Caco-2 cells, and the PIE peptide was identified in the serum after the mice reached the highest value of 173.60 ± 60.30 ng/mL, in which it was quantified by an optimized mass spectrometry method. In addition, the PIE peptide has a promoting effect on the bone morphogenetic protein pathway at the gene and protein levels. According to the distribution of PIE-FITC in ovariectomized mice after orally administrated PIE-FITC, it was confirmed that it can enter the gastrointestinal tract and serum, and reach the bones. Taken together, the PIE peptide can be absorbed well both in vitro and in vivo, and it could promote pre-osteoblast differentiation factors.

Paget Disease of Bone for Primary Care

Paget disease of bone is a benign disorder characterized by focal areas of increased bone turnover in one or more skeletal sites. It usually affects older adults, and men are at a higher risk than women. Any bone may be affected, but the disease has a high preference for the pelvis, spine, skull, and long bones. Pain is the most common symptom, and presentation of the disease may depend on which bones are affected, the extent of involvement, and the presence of complications. Paget disease of bone may be asymptomatic, and suspicion arises from incidental findings of elevated serum alkaline phosphatase levels on routine blood work or abnormalities on imaging tests performed for an unrelated cause. Evidence-based guidelines recommend the use of plain radiography and serum alkaline phosphatase testing for initial diagnosis and radionuclide scans for delineation of the extent of disease. Treatment with nitrogen-containing bisphosphonates is recommended in active disease or when risk of complications is possible. Complications of the disease include arthritis, gait changes, hearing loss, nerve compression syndromes, and osteosarcoma. Total serum alkaline phosphatase is the suggested marker for assessing treatment response when high bone turnover occurs, and it should be measured at three to six months to evaluate initial response. Early diagnosis of Paget disease of bone remains key to its management because patients generally have a good prognosis if treatment is initiated before major complications arise. The primary care physician may need to consult with a specialist for confirmation of diagnosis and initiation of treatment.

A Dairy Product to Reconstitute Enriched with Bioactive Nutrients Stops Bone Loss in High-Risk Menopausal Women without Pharmacological Treatment

Osteoporosis is a multifactorial disease characterized by the loss of bone mass and deterioration of the internal structure of the bone, increasing the risk of fractures, and is becoming an economic and social problem. The main treatment is pharmacological, however, the population demands other therapies, such as foods with nutrients beneficial to bone health. Seventy-eight healthy menopausal women at risk of osteoporosis or untreated osteopenia were recruited for a randomized, parallel, double-blind clinical trial with two intervention groups: one group consumed a serving a day of the experimental enriched product (experimental group (EG)) and the other group (control group (CG)) consumed the same product without enrichment. The main objective was to compare the effect of consuming a dairy preparation to reconstitute, similar to yogurt when prepared, enriched in calcium, vitamin D, vitamin K, vitamin C, zinc, magnesium, L-leucine and probiotic (Lactobacillus plantarum 3547) on bone metabolism markers for 24 weeks. The EG showed a significantly increased bone mass compared to the CG (0.01 ± 0.03 vs. −0.01 ± 0.03 kg; p < 0.05). In addition, the EG maintained their bone mineral density (BMD) compared to the CG, whose BMD significantly decreased at the end of the study. For biochemical markers, the EG significantly increased the serum levels of the N-terminal propeptide of type I collagen (P1NP) bone formation marker (13.19 ± 25.17 vs. −4.21 ± 15.62 ng/mL; p < 0.05), and decreased the carbo-terminal telopeptide of type I collagen (CTx) bone resorption marker compared to the CG (−0.05 ± 0.19 vs. 0.04 ± 0.14 ng/mL; p < 0.05). On the other hand, the EG exhibited a significantly decreased systolic and diastolic blood pressure compared to the start of the study. Finally, the EG significantly increased their dietary calcium and vitamin D intake compared to the CG. In conclusion, the regular consumption of a dairy product to reconstitute enriched with bioactive nutrients improves bone health markers in menopausal women at risk of osteoporosis without pharmacological treatment.

Sleep Restriction With Circadian Disruption Negatively Alter Bone Turnover Markers in Women

PURPOSE

The purpose of this work is to determine whether an uncoupling of bone turnover markers (BTMs) occurs in women exposed to the combination of sleep restriction with circadian disruption (SRCD), as previously reported in men.

METHODS

Four bone biomarkers (N-terminal propeptide of type I procollagen [P1NP] and osteocalcin = bone formation; C-telopeptide [CTX] = bone resorption; sclerostin = bone formation inhibitor) were measured in bihourly samples over 24 hours at baseline and after approximately 3 weeks of sleep restriction (~5.6 hours of sleep/24 hours) with concurrent circadian disruption (SRCD, recurring 28-hour "day" in dim light). Maximum likelihood estimation in a repeated-measures model was used to assess the effects of SRCD and age on bone biomarkers.

RESULTS

Five women were young (22 ± 2.8 years) and four were older (58 ± 1.8 years). Baseline bone biomarker levels did not differ by age (all P ≥ .07). Bone formation markers were lower after SRCD (estimate ± SEE, ΔP1NP = -9.5 ± 2.8 μg/L, P = .01; Δosteocalcin = -2.3 ± 0.9 ng/mL, P = .04). The P1NP decline was greater in young women (ΔP1NP = -12.9 ± 3.7 μg/L, P = .01). After SRCD, CTX was significantly higher in young women (0.182 ± 0.069 ng/mL, P = .04) but did not change in older women.

CONCLUSIONS

These pilot data are similar to previous findings in men and suggest that SRCD negatively altered bone metabolism in women by decreasing markers of bone formation and, in young women, increasing a marker of bone resorption. If sustained, this pattern of BTM uncoupling may lead to bone loss and lower bone mineral density.

Trunk and Lower Extremity Movement Patterns, Stress Fracture Risk Factors, and Biomarkers of Bone Turnover in Military Trainees

CONTEXT

Military service members commonly sustain lower extremity stress fractures (SFx). How SFx risk factors influence bone metabolism is unknown. Understanding how SFx risk factors influence bone metabolism may help to optimize risk-mitigation strategies.

OBJECTIVE

To determine how SFx risk factors influence bone metabolism.

DESIGN

Cross-sectional study.

SETTING

Military service academy.

PATIENTS OR OTHER PARTICIPANTS

Forty-five men (agepre = 18.56 ± 1.39 years, heightpre = 176.95 ± 7.29 cm, masspre = 77.20 ± 9.40 kg; body mass indexpre = 24.68 ± 2.87) who completed Cadet Basic Training (CBT). Individuals with neurologic or metabolic disorders were excluded.

INTERVENTION(S)

We assessed SFx risk factors (independent variables) with (1) the Landing Error Scoring System (LESS), (2) self-reported injury and physical activity questionnaires, and (3) physical fitness tests. We assessed bone biomarkers (dependent variables; procollagen type I amino-terminal propeptide [PINP] and cross-linked collagen telopeptide [CTx-1]) via serum.

MAIN OUTCOME MEASURE(S)

A markerless motion-capture system was used to analyze trunk and lower extremity biomechanics via the LESS. Serum samples were collected post-CBT; enzyme-linked immunosorbent assays determined PINP and CTx-1 concentrations, and PINP : CTx-1 ratios were calculated. Linear regression models demonstrated associations between SFx risk factors and PINP and CTx-1 concentrations and PINP : CTx-1 ratio. Biomarker concentration mean differences with 95% confidence intervals were calculated. Significance was set a priori using α ≤ .10 for simple and α ≤ .05 for multiple regression analyses.

RESULTS

The multiple regression models incorporating LESS and SFx risk factor data predicted the PINP concentration (R2 = 0.47, P = .02) and PINP : CTx-1 ratio (R2 = 0.66, P = .01). The PINP concentration was increased by foot internal rotation, trunk flexion, CBT injury, sit-up score, and pre- to post-CBT mass changes. The CTx-1 concentration was increased by heel-to-toe landing and post-CBT mass. The PINP : CTx-1 ratio was increased by foot internal rotation, lower extremity sagittal-plane displacement (inversely), CBT injury, sit-up score, and pre- to post-CBT mass changes.

CONCLUSIONS

Stress fracture risk factors accounted for 66% of the PINP : CTx-1 ratio variability, a potential surrogate for bone health. Our findings provide insight into how SFx risk factors influence bone health. This information can help guide SFx risk-mitigation strategies.

Cytokines in the grass, a lesson learnt: Measuring cytokines in plasma using multiple reaction monitoring mass spectrometry

RATIONALE

Cytokines are cell regulatory molecules of high importance as indicators for homeostasis and pathology in many species. The current method to measure cytokines in body fluids is reagent dependent, requiring highly specific paired antibodies.

METHODS

A liquid chromatography/multiple reaction monitoring mass spectrometry (LC/MRM-MS)-based approach was developed to simultaneously establish the limits of detection (LODs) and quantification (LOQs) for recombinant cytokines IL-1β, IL-6, IFNγ and TNFα as pure standards and in bovine sera. All experimental LC/MRM-MS data are available at CSIRO Data Access Portal repository under identifier doi.org/10.25919/5de8a0232a862.

RESULTS

The present method enabled LODs and LOQs as low as 1.05 and 1.12 fmol/μL in the experiment comprised of pure standards. Comparable results were obtained in the experiment where digested cytokines were mixed with pre-digested sera proteins. The intrinsic matrix effects were evident when intact cytokines were co-digested within undiluted and undigested sera decreasing the ability to detect and quantify cytokines by 10,000-fold compared with pure standards and pre-digested sera.

CONCLUSIONS

The developed LC/MRM-MS method provided insights into the difficulties in detecting the target peptides when embedded in complex matrices. Nonetheless, the method may potentially be readily applied in biomarker-focused research interrogating fluids of lesser complexity such as synovial fluid, cerebrospinal fluid and tissue culture media.

The Impact of Mild Autonomous Cortisol Secretion on Bone Turnover Markers

CONTEXT

Several studies have reported increased risk of fragility fractures in patients with mild autonomous cortisol secretion (MACS), discordant to the degree of bone density deterioration.

OBJECTIVE

To evaluate the effect of MACS on bone metabolism in patients with adrenal adenomas.

DESIGN

Cross-sectional study with prospective enrollment, 2014-2019.

SETTING

Referral center.

PATIENTS

213 patients with adrenal adenomas: 22 Cushing syndrome (CS), 92 MACS and 99 nonfunctioning adrenal tumors (NFAT).

MAIN OUTCOME MEASURES

Osteocalcin, procollagen I intact N-terminal (PINP), C-terminal telopeptide (CTX), sclerostin.

RESULTS

Patients with CS demonstrated lower markers of bone formation compared with patients with MACS and NFAT (CS vs MACS vs NFAT: mean osteocalcin 14.8 vs 20.1 vs 21.3 ng/mL [P < 0.0001]; mean PINP 34.8 vs 48.7 vs 48.5 µg/L [P = 0.003]). Severity of cortisol excess was inversely associated with sclerostin (CS vs MACS vs NFAT: mean sclerostin 419 vs 538 vs 624 ng/L, [P < 0.0001]). In a multivariable model of age, sex, body mass index, cortisol, and bone turnover markers, sclerostin was a significant predictor of low bone mass in patients with MACS (OR 0.63 [CI 95%, 0.40-0.98] for each 100 ng/L of sclerostin increase).After adrenalectomy, osteocalcin, CTX, and sclerostin increased by a mean difference of 6.3 ng/mL, 0.12 ng/mL, and 171 pg/mL (P = 0.02 for all), respectively.

CONCLUSIONS

Lower sclerostin level in patients with MACS reflects a reduction in osteocyte function or number associated with exposure to chronic cortisol excess. Increase in bone turnover markers after adrenalectomy suggests restoration of favorable bone metabolism.

Fully automated dried blood spot sample preparation enables the detection of lower molecular mass peptide and non-peptide doping agents by means of LC-HRMS

The added value of dried blood spot (DBS) samples complementing the information obtained from commonly routine doping control matrices is continuously increasing in sports drug testing. In this project, a robotic-assisted non-destructive hematocrit measurement from dried blood spots by near-infrared spectroscopy followed by a fully automated sample preparation including strong cation exchange solid-phase extraction and evaporation enabled the detection of 46 lower molecular mass (< 2 kDa) peptide and non-peptide drugs and drug candidates by means of LC-HRMS. The target analytes included, amongst others, agonists of the gonadotropin-releasing hormone receptor, the ghrelin receptor, the human growth hormone receptor, and the antidiuretic hormone receptor. Furthermore, several glycine derivatives of growth hormone–releasing peptides (GHRPs), arguably designed to undermine current anti-doping testing approaches, were implemented to the presented detection method. The initial testing assay was validated according to the World Anti-Doping Agency guidelines with estimated LODs between 0.5 and 20 ng/mL. As a proof of concept, authentic post-administration specimens containing GHRP-2 and GHRP-6 were successfully analyzed. Furthermore, DBS obtained from a sampling device operating with microneedles for blood collection from the upper arm were analyzed and the matrix was cross-validated for selected parameters. The introduction of the hematocrit measurement method can be of great value for doping analysis as it allows for quantitative DBS applications by managing the well-recognized “hematocrit effect.”

Soluble Biomarkers of Osteoporosis and Osteoarthritis, from Pathway Mapping to Clinical Trials: An Update

Serum biomarkers of osteoarticular diseases have been in the limelight of current clinical research trends. Laboratory validation of defined and candidate biomarkers for both osteoarthritis and osteoporosis is of key importance for future decisional algorithms in the diagnosis, monitoring, and prognosis of these diseases. The current guidelines recommend the use of collagen degradation remnants, eg, CTX-I and CTX-II, in the complementary diagnosis of both osteoporosis and osteoarthritis. Besides the collagen degradation markers, enzymes that regulate bone and articular metabolism are useful in the clinical evaluation of osteoarticular pathologies. Along these, several other recommended and new nominee molecules have been recently studied. Wnts and Wnt-related molecules have a cardinal role in the bone-joint homeostasis, making them a promising target not only for pharmaceutical modulation, but also to be considered as soluble biomarkers. Sclerostin and dickkopf, two inhibitor molecules of the Wnt/β-catenin signaling, might have a dual role in the assessment of the clinical manifestations of the osteoarticular unit. In osteoarthritis, besides fragments of collagen type II many pathway-related molecules have been studied and proposed for biomarker validation. The most serious limitation is that a significant proportion of studies lack statistical power due to the reduced number of cases enrolled. Serum biomarkers of bone and joint turnover markers represent an encouraging possibility for the diagnosis and prognosis of osteoarticular diseases, although further studies and laboratory validations should be carried out as to solely rely on them.

Differential processing of high-molecular-weight kininogen during normal pregnancy

RATIONALE

Studies identified kininogen as a potential biomarker of preeclampsia, a major cause of adverse maternal outcomes. High-molecular-weight kininogen (HK) and its activated form participate in numerous pathways associated with establishing and maintaining pregnancy. However, dynamic changes in HK and naturally occurring HK-derived peptides during the natural course of pregnancy are largely unknown.

METHODS

Longitudinal serum samples during the course of normal pregnancy (trimesters T1, T2, T3) from 60 pregnant women were analyzed by western blot with an anti-HK antibody. Circulating peptides in longitudinal serum specimens derived from 50 participants were enriched using nanoporous silica thin films. Peptides were identified by liquid chromatography/tandem mass spectrometry (LC/MS/MS) and database searching. Relative quantification was performed using MaxQuant and in-house scripts. Normality was evaluated by either ANOVA or Friedman tests with p < 0.05 for statistical significance.

RESULTS

Western blotting revealed that HK significantly decreased during normal pregnancy (T1 vs T2, p < 0.05; T1 vs T3, p < 0.0001). A 100 kDa intermediate increased during pregnancy (T1 vs T2, p < 0.005; T1 vs T3, p < 0.01). Moreover, the heavy chain (T1 vs T2, p < 0.0001; T1 vs T3, p < 0.0001; T2 vs T3, p < 0.01) and light chain (T1 vs T2, p < 0.0001; T1 vs T3, p < 0.0001; T2 vs T3, p < 0.05) significantly increased during pregnancy. LC/MS/MS analysis identified 180 kininogen-1 peptides, of which 167 mapped to domain 5 (D5). Seventy-three peptides with ten or more complete data sets were included for further analysis. Seventy peptides mapped to D5, and 3, 24, and 43 peptides showed significant decrease, no trend, and significant increase, respectively, during pregnancy.

CONCLUSIONS

This study demonstrates dynamic changes in HK and naturally occurring HK-derived peptides during pregnancy. Our study sheds light on the gestational changes of HK and its peptides for further validation of them as potential biomarkers for pregnancy-related complications.

Alcohol and Bone Turnover Markers among People Living with HIV and Substance Use Disorder

BACKGROUND

Although unhealthy alcohol use and low bone density are prevalent among people living with HIV (PLWH), it is not clear whether alcohol use is associated with bone turnover markers (BTMs), and if so, at what quantity and frequency. The study objective was to examine the association between alcohol and BTMs in PLWH with substance use disorder.

METHODS

We studied a prospective cohort recruited from 2 HIV clinics who met criteria for DSM-IV substance dependence or reported ever injection drug use. Outcomes were BTM of (i) bone formation (serum procollagen type 1 N-terminal propeptide [P1NP]) and (ii) bone resorption (serum C-telopeptide type 1 collagen [CTx]). Alcohol consumption measures included (i) mean number of drinks/d (Timeline Follow-Back [TLFB]) (primary predictor), (ii) any alcohol use on ≥20 of the past 30 days, and phosphatidylethanol (PEth), a biomarker of recent alcohol consumption. Linear regression analysis examined associations between (i) each alcohol measure and each BTM and (ii) change in alcohol and change in BTM over 12 months.

RESULTS

Among 198 participants, baseline characteristics were as follows: The median age was 50 years; 38% were female; 93% were prescribed antiretroviral medications; 13% had ≥20 drinking days/month; mean drinks/day was 1.93 (SD 3.89); change in mean drinks/day was -0.42 (SD 4.18); mean P1NP was 73.1 ng/ml (SD 34.5); and mean CTx was 0.36 ng/ml (SD 0.34). Higher drinks/day was significantly associated with lower P1NP (slope -1.09 ng/ml; 95% confidence interval [CI] -1.94, -0.23, per each additional drink). On average, those who drank on ≥ 20 days/month had lower P1NP (-15.45 ng/ml; 95% CI: -26.23, -4.67) than those who did not. Similarly, PEth level ≥ 8ng/ml was associated with lower P1NP. An increase in drinks/d was associated with a decrease in P1NP nonsignificantly (-1.14; 95% CI: -2.40, +0.12; p = 0.08, per each additional drink). No significant associations were detected between either alcohol measure and CTx.

CONCLUSIONS

In this sample of PLWH with substance use disorder, greater alcohol consumption was associated with lower serum levels of bone formation markers.

Effect of continuous long-term treatment for 10 years with bisphosphonate on Japanese osteoporosis patients

INTRODUCTION

In terms of the balance between benefits and risks of long-term treatment with bisphosphonate, uncertainties remain regarding the optimal treatment duration. We investigated effects of continuous long-term treatment for 10 years with bisphosphonate in postmenopausal osteoporosis patients.

MATERIALS AND METHODS

Fifty five patients in the outpatient clinic of our hospital have been continuously treated with alendronate or risedronate for 10 years. All data were retrospectively collected. The age, height, weight, total muscle volume, total fat volume, and BMD at the lumbar spine, total hip and distal 1/3 radius, alkaline phosphatase (ALP), urinary type I collagen cross-linked N-telopeptide (uNTX) and tartrate-resistant acid phosphatase-5b (TRAP5b), calcium (Ca) and phosphate (P) levels were measured pre- and after the start of 10-year continuous treatment.

RESULTS

BMD at the lumbar spine increased continuously over the 10-year period, while BMD at the total hip slightly but significantly decreased, and that at the 1/3 radius did not show any significant change over the 10 years. Serum Ca value was significantly decreased after the start of treatment, and became stable within the reference range from the second year. Bone resorption markers such as uNTX and TRAP5b significantly decreased from the second year after the start of treatment and no significant changes were observed thereafter. There were no serious medical adverse events including atypical femoral fractures and osteonecrosis of the jaw.

CONCLUSION

We believe that the continuous use of alendronate and risedronate for 10 years could be an option for the treatment of postmenopausal osteoporosis patients.

Concentration Determination of >200 Proteins in Dried Blood Spots for Biomarker Discovery and Validation

The use of protein biomarkers as surrogates for clinical endpoints requires extensive multilevel validation including development of robust and sensitive assays for precise measurement of protein concentration. Multiple reaction monitoring (MRM) is a well-established mass-spectrometric method that can be used for reproducible protein-concentration measurements in biological specimens collected via microsampling. The dried blood spot (DBS) microsampling technique can be performed non-invasively without the expertise of a phlebotomist, and can enhance analyte stability which facilitate the application of this technique in retrospective studies while providing lower storage and shipping costs, because cold-chain logistics can be eliminated. Thus, precise, sensitive, and multiplexed methods for measuring protein concentrations in DBSs can be used for de novo biomarker discovery and for biomarker quantification or verification experiments. To achieve this goal, MRM assays were developed for multiplexed concentration measurement of proteins in DBSs.The lower limit of quantification (LLOQ) was found to have a median total coefficient of variation (CV) of 18% for 245 proteins, whereas the median LLOQ was 5 fmol of peptide injected on column, and the median inter-day CV over 4 days for measuring endogenous protein concentration was 8%. The majority (88%) of the assays displayed parallelism, whereas the peptide standards remained stable throughout the assay workflow and after exposure to multiple freeze-thaw cycles. For 190 proteins, the measured protein concentrations remained stable in DBS stored at ambient laboratory temperature for up to 2 months. Finally, the developed assays were used to measure the concentration ranges for 200 proteins in twenty same sex, same race and age matched individuals.

Plasma Peptide Concentrations and Peptide-Reactive Immunoglobulins in Patients with Eating Disorders at Inclusion in the French EDILS Cohort (Eating Disorders Inventory and Longitudinal Survey)

Eating disorders (EDs) are increasingly frequent. Their pathophysiology involves disturbance of peptide signaling and the microbiota–gut–brain axis. This study analyzed peptides and corresponding immunoglobulin (Ig) concentrations in groups of ED. In 120 patients with restrictive (R), bulimic (B), and compulsive (C) ED, the plasma concentrations of leptin, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and insulin were analyzed by Milliplex and those of acyl ghrelin (AG), des-acyl ghrelin (DAG), and α-melanocyte-stimulating hormone (α-MSH) by ELISA kits. Immunoglobulin G (in response to an antigen) concentrations were analyzed by ELISA, and their affinity for the respective peptide was measured by surface plasmon resonance. The concentrations of leptin, insulin, GLP-1, and PYY were higher in C patients than in R patients. On the contrary, α-MSH, DAG, and AG concentrations were higher in R than in C patients. After adjustment for body mass index (BMI), differences among peptide concentrations were no longer different. No difference in the concentrations of the IgG was found, but the IgG concentrations were correlated with each other. Although differences of peptide concentrations exist among ED subtypes, they may be due to differences in BMI. Changes in the concentration and/or affinity of several anti-peptide IgG may contribute to the physiopathology of ED or may be related to fat mass.