Deoxypyridinoline Crosslinks Research Articles

Evaluation of bone mineral density in children with type 1 diabetes: A cross-sectional case–control study

Objectives: To compare the bone mineral density (BMD) and vitamin D levels of children with type 1 diabetes (T1D) with normal children. Material and Methods: Children with T1D, aged 4–18 years, and age- and gender-matched healthy controls, were recruited. Children with chronic systemic disorders and those taking medications that impair BMD were excluded from the study. Dual-energy X-ray absorptiometry, vitamin D, intact parathyroid hormone, calcium, phosphorus, alkaline phosphatase, osteocalcin, and spot urine deoxypyridinoline crosslinks (Pyrilinks-D)/ creatinine ratio were estimated in both cases and controls. Results: Thirty-seven children with T1D with a mean age of 9.7 ± 2.1 years were enrolled and compared with controls. The bone mineral content (BMC) in cases was 24.5 g (20.3–30.6) and in controls 25.5 g (23.5–26.8) (P = 0.66) and BMD in cases was 0.68 ± 0.165 g/cm2 and in controls 0.69 ± 0.149 g/cm2 (P = 0.76). However, the prevalence of low BMD (BMD <-2 Z-score) was seen in only 3 (8%) cases (P – <0.001). Serum 25-hydroxyvitamin D [25(OH)D] levels were also lower in cases 14.1 ng/mL (12.05–14.75 ng/mL) as compared to controls 15.73 ng/mL (13.1–23.2 ng/mL) (P = 0.01). Thirty-three (89%) cases and 24 (64%) controls had low 25(OH)D levels (<20 ng/mL). There was no significant difference in the bone turnover markers between cases and controls. Conclusion: Children with T1D have similar BMD and lower vitamin D levels compared to healthy children.

Increased Collagen Crosslinking in Stiff Clubfoot Tissue: Implications for the Improvement of Therapeutic Strategies.

Congenital clubfoot is a complex musculoskeletal deformity, in which a stiff, contracted tissue forms in the medial part of the foot. Fibrotic changes are associated with increased collagen deposition and lysyl oxidase (LOX)-mediated crosslinking, which impair collagen degradation and increase the tissue stiffness. First, we studied collagen deposition, as well as the expression of collagen and the amount of pyridinoline and deoxypyridinoline crosslinks in the tissue of relapsed clubfoot by immunohistochemistry, real-time PCR, and enzyme-linked immunosorbent assay (ELISA). We then isolated fibroblast-like cells from the contracted tissue to study the potential inhibition of these processes in vitro. We assessed the effects of a LOX inhibitor, β-aminopropionitrile (BAPN), on the cells by a hydroxyproline assay, ELISA, and Second Harmonic Generation imaging. We also evaluated the cell-mediated contraction of extracellular matrix in 3D cell-populated collagen gels. For the first time, we have confirmed significantly increased crosslinking and excessive collagen type I deposition in the clubfoot-contracted tissue. We successfully reduced these processes in vitro in a dose-dependent manner with 10–40 µg/mL of BAPN, and we observed an increasing trend in the inhibition of the cell-mediated contraction of collagen gels. The in vitro inhibitory effects indicate that BAPN has good potential for the treatment of relapsed and resistant clubfeet.

Mice lacking substance P have normal bone modeling but diminished bone formation, increased resorption, and accelerated osteopenia with aging.

Substance P (SP) is a sensory neuropeptide that is expressed by the neurons innervating bone. There is considerable evidence that SP can regulate bone cell function in vitro, but it is unclear whether SP modulates bone modeling or remodeling in vivo. To answer this question we characterized the bone phenotype of mice with deletion of the Tac1 gene expressing SP. The phenotypes of 2-month-old and 5-month-old SP deficient mice and their wildtype controls were characterized by using μCT imaging, static and dynamic bone histomorphometry, and urinary deoxypyridinoline cross-links (DPD) measurement. No differences in bone phenotypes were observed between the 2 strains at 2months of age. By 5months both the wildtype and SP deficient mice had developed cancellous osteopenia, but relative to the wild-type mice the SP deficient mice had significantly greater cancellous bone loss. The SP deficient mice also exhibited decreased bone formation, increased osteoclast number, and increased urinary DPD levels. Cortical defect early repair was delayed in 5-month-old mice lacking SP. Collectively, these findings indicate that SP signaling is not required for bone modeling, but SP signaling reduces age-related osteopenia and accelerates cortical defect reparation, data supporting the hypothesis that SP is an anabolic physiologic regulator of bone metabolism.

N-Homocysteinylation impairs collagen cross-linking in cystathionine β-synthase-deficient mice: a novel mechanism of connective tissue abnormalities.

Cystathionine β-synthase (CBS) deficiency, a genetic disorder in homocysteine (Hcy) metabolism in humans, elevates plasma Hcy-thiolactone and leads to connective tissue abnormalities that affect the cardiovascular and skeletal systems. However, the underlying mechanism of these abnormalities is not understood. Hcy-thiolactone has the ability to form isopeptide bonds with protein lysine residues, which generates N-homocysteinylated protein. Because lysine residues are involved in collagen cross-linking, N-homocysteinylation of these lysines should impair cross-linking. Using a Tg-I278T Cbs-/- mouse model of hyperhomocysteinemia (HHcy) which replicates the connective tissue abnormalities observed in CBS-deficient patients, we found that N-Hcy-collagen was elevated in bone, tail, and heart of Cbs-/- mice, whereas pyridinoline cross-links were significantly reduced. Plasma deoxypyridinoline cross-link and cross-linked carboxyterminal telopeptide of type I collagen were also significantly reduced in the Cbs-/- mice. Lysine oxidase activity and mRNA level were not reduced by the Cbs-/- genotype. We also showed that collagen carries S-linked Hcy bound to the thiol of N-linked Hcy. In vitro experiments showed that Hcy-thiolactone modifies lysine residues in collagen type I α-1 chain. Residue K160, located in the nonhelical N-telopeptide region and involved in pyridinoline cross-link formation, was also N-homocysteinylated in vivo Taken together, our findings showed that N-homocysteinylation of collagen in Cbs-/- mice impairs its cross-linking. These findings explain, at least in part, connective tissue abnormalities observed in HHcy.-Perła-Kajan, J., Utyro, O., Rusek, M., Malinowska, A., Sitkiewicz, E., Jakubowski, H. N-Homocysteinylation impairs collagen cross-linking in cystathionine β-synthase-deficient mice: a novel mechanism of connective tissue abnormalities.

Bone Mineral Density and Bone Turnover Markers Under Bisphosphonate Therapy Used in the First Year After Liver Transplantation.

BACKGROUND Rapid bone loss occurs early after liver transplantation (Tx), concomitantly with intensified bone turnover. In the present study we investigated the effect of bisphosphonates (bisph) added to vitamin D (vitD) and calcium on bone mineral density (BMD) and bone biomarkers in liver graft recipients in the first posttransplant year. MATERIAL AND METHODS In 28 patients BMD was determined at the third month after Tx. In case of osteopenia (Tscore ≤-1.0) and no contraindications, oral bisph was started for 1 year (group BP, n=14); other patients served as controls (CON, n=14). The changes in BMD and biomarkers of bone formation were osteocalcin (OC), bone alkaline phosphatase (BAP), and resorption. Study endpoints were active isoform 5b of the tartrate-resistant acid phosphatase (TRACP5b), serum pyridinoline crosslinks (PYD), and urine excretion of deoxypyridinoline (Dpd) crosslinks. RESULTS In 19 (68%) patients, reduced BMD (T-score ≤1.0) was observed at baseline. The changes in lumbar BMD in BP and CON groups were 5.2% and 1.5%, respectively, not reaching statistical significance. Baseline PYD, Dpd/creat, and OC were elevated in all patients, indicating high bone turnover. We observed decrease in PYD and Dpd/creat in both groups; however, OC decreased only under bisph therapy. Increase in BAP was observed in the control group but not in the BP group. The changes in BAP and OC were significantly different (p<0.01). CONCLUSIONS Combining bisph with vitD and calcium is an effective bone- sparing strategy in liver transplant recipients in the first posttransplant year. Bisph more efficiently decreased the rate of bone turnover than vitD and calcium alone.

Coordinate regulatory osteogenesis effects of icariin, timosaponin B II and ferulic acid from traditional Chinese medicine formulas on UMR-106 osteoblastic cells and osteoblasts in neonatal rat calvaria cultures

Ethnopharmacological significanceIcariin (I), ferulic acid (F) and timosaponin B II (T) derived respectively from the leaf of Epimedium brevicornu Maxim (EBM, Berberidaceae), rhizome of Anemarrhena asphodeloides Bunge (AAB, Liliaceae) and root of Angelica sinensis (Oliv.) Diels (ASD, Umbelliferae) are included in several traditional Chinese medicine (TCM) formulas for the treatment of osteoporosis. In addition, the medicinal materials and chemical constituents in many traditional Chinese formulas have been shown to have potential synergistic, additive and antagonistic effects. Aim of studyTo explore the action mechanism and interactions between I, T and F as bone anabolic ingredients on osteoblasts, and fully understand their action mechanism and rationality of the formula design. Materials and methodsAn osteoporotic model was established in bilaterally ovariectomized mice. Bone mineral density (BMD), bone mineral content (BMC) and serum biochemical parameters including alkaline phosphatase (ALP), tartrate resistant acid phosphatase (TRAP), osteoprotegerin (OPG) and deoxypyridinoline cross-links (DPD) were measured to evaluate the effects of I, T or F alone and their combinations on osteoporotic mice. UMR-106 osteoblastic cells and primary osteoblasts in neonatal rat calvarias were used to evaluate the osteogenesis effect. The immunohistochemical method and Western-blot analysis were used to detect the expression of critical proteins in the process of proliferation and differentiation of osteoblasts. ResultsIFT combinations enhanced the therapeutic effect without increasing the adverse effects on osteoporotic mice, synergistically increased the osteoblast proliferation, ALP activity and mineralized nodule formation, and promoted the expression of bone matrix by regulating BMP and Wnt/β-catenin signaling pathways in osteoblasts. ConclusionIFT combinations reinforced the therapeutic effect on osteoporosis by modulating multi-signaling pathways and action targets.

Changes in Urinary Bone Resorption Marker after Taking a Combination Nutrient Formula in Adults with Scoliosis: A Retrospective, Open-Label, Case-Controlled Series

Background: Scoliosis is a common condition in adult patients, and often causes chronic back pain compared to non-scoliosis. It has also been identified that bone mineral density is very often compromised in patients with scoliosis, even occurring in adolescence. At this time, no study has looked at how bone mineral density and scoliosis incidence or severity may be connected with specific regard to treatment. This study presents data on the outcomes of a scoliosis-specific exercise therapy and its ability to correct scoliotic curvatures in adult patients alone and in combination with bone mineral density supplementation. Methods: The charts of 14 total patients were retrospectively selected based upon specific inclusion criteria. Outcome assessments included the radiographic Cobb angle of the primary curvature, as well as laboratory measures of urinary deoxypyridinoline cross links. These results were compared against 12 patients who did not take the bone density supplement during or after their exercise-based treatment. Results: Patients taking the bone density supplement achieved the same level of Cobb angle reduction as compared to the control group. However, they additionally achieved a significant reduction in urinary deoxypyridinoline cross links as compared to the control group at 6 months. Conclusion: Patients taking a multi-ingredient bone density supplement daily for 6 months after completing a scoliosis-specific exercise program reported statistically significant improvements in urinary deoxypyridinoline cross links as compared to controls. It is unknown if or how bone density loss may contribute to the onset or progression of scoliosis. Long-term follow-up of these patients will be ongoing to assess bone mineral density status and Cobb angle changes longitudinally.

Antiosteoporotic activity and constituents of Podocarpium podocarpum

Our study aimed to investigate the antiosteoporotic properties of the ethanol extract of Podocarpium podocarpum (DC.) Yang et Huang (PE) in ovariectomized (OVX) rats and to characterize the active constituents. As a result, PE significantly inhibited the increased urinary Ca excretion and activity of bone resorption markers including tartrate-resistant acid phosphatase (TRAP), deoxypyridinoline crosslinks and cathepsin K in OVX rats, whereas exhibited little effects on the body, uterus and vagina weight. Detailed micro-CT analysis showed that PE notably enhanced bone quality, with increased bone mineral content (BMC), bone volume fraction (BVF), connectivity density (CD), tissue mineral content (TMC), tissue mineral density (TMD) and trabecular number (Tb. N), and decreased trabecular separation (Tb. Sp), in OVX animal. Those findings implied that PE had notable antiosteoporotic effect, especially effective in preventing bone resorption, with little side-effects on reproductive tissue. Further chemical investigation led to the isolation of 17 flavonoids, most of which showed significantly stimulatory effect on osteoblastic proliferation, ALP activity and mineralized nodes formation as well as inhibitory effect on osteoclastic TRAP activity in osteoblastic and osteoclastic cells. Our results indicated that PE, with abundant flavonoids, had remarkable antiosteoporotic activity and therefore can be a promising candidate for the treatment of postmenopausal osteoporosis induced by estrogen deficiency through herbal remedy.

Collagen cross-links as a marker for subclinical atherosclerosis in postmenopausal women

This study aimed to examine the utility of pyridinoline (Pyd) and deoxypyridinoline (Dpd) cross-links in the detection of subclinical atherosclerosis in postmenopausal women with or without osteoporosis. We measured Pyd, Dpd, carotid intima-media thickness (CIMT), fasting total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and blood pressure in 59 healthy postmenopausal women: 30 had normal bone mineral density (group I) and the remaining 29 had osteoporosis or osteopenia (group II) according to World Health Organization criteria. There were no statistically significant differences in age, duration of menopause, age at menopause, lipid profile, body mass index, Pyd level, Dpd level, and Pyd-to-Dpd ratio between the groups (P > 0.05). No significant difference in CIMT was found when groups I and II were compared (P = 0.538). No statistically significant differences in Pyd level, Dpd level, and Pyd-to-Dpd ratio were found when women with CIMT higher than 5 mm and women with CIMT of 5 mm or less were compared in groups I and II (P > 0.05). However, significantly declined Dpd level and increased Pyd-to-Dpd ratio were found in women with CIMT higher than 5 mm when compared with women with CIMT of 5 mm or less. CIMT was found to be negatively correlated with Dpd level (r = -0.346, P = 0.007) and to be positively correlated with the Pyd-to-Dpd ratio (r = 0.702, P < 0.001). The increase in the Pyd-to-Dpd ratio, irrespective of the participants' bone mineral density, may have predictive value in the determination of subclinical atherosclerosis in postmenopausal women.

Appliance‐induced osteopenia of dentoalveolar bone in the rat: effect of reduced bone strains on serum bone markers and the multifunctional hormone leptin

To understand, in greater detail, the molecular mechanisms regulating the complex relationship between mechanical strain and alveolar bone metabolism during orthodontic treatment, passive cross-arch palatal springs were bonded to the maxillary molars of 6-wk-old rats, which were killed after 4 and 8 d. Outcome measures included serum assays for markers of bone formation and resorption and for the multifunctional hormone leptin, and histomorphometry of the inter-radicular bone. The concentration of the bone-formation marker alkaline phosphatase (ALP) was significantly reduced at both time points in the appliance group, accompanied by a 50% reduction in inter-radicular bone volume; however, osteocalcin (bone Gla protein) levels remained unaffected. Bone collagen deoxypyridinoline (DPD) crosslinks increased 2.3-fold at 4 d only, indicating a transient increase in bone resorption; in contrast, the level of the osteoclast-specific marker, tartrate-resistant acid phosphatase 5b (TRACP 5b), was unchanged. Leptin levels closely paralleled ALP reductions at both time points, suggesting an important role in the mechanostat negative-feedback loop required to normalize bone mass. These data suggest that an orthodontic appliance, in addition to remodeling the periodontal ligament (PDL)-bone interface, may exert unexpected side-effects on the tooth-supporting alveolar bone, and highlights the importance of recognizing that bone strains can have negative, as well as positive, effects on bone mass.

Periarticular Bone Gain at Proximal Interphalangeal Joints and Changes in Bone Turnover Markers in Response to Tumor Necrosis Factor Inhibitors in Rheumatoid and Psoriatic Arthritis

Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are characterized by periarticular bone erosion; periarticular bone formation is a feature in PsA. The effect of anti-tumor necrosis factor-α (TNF-α) on periarticular bone remodeling is unclear in both diseases. Our aim was to assess the response of bone turnover markers (BTM) and hand bone mineral density (BMD) to anti-TNF over 3 years in RA and PsA. We measured serum bone-specific alkaline phosphatase (bone ALP), procollagen type-I N-propeptide (PINP), intact osteocalcin, C-terminal cross-linking telopeptides (CTX-I), urinary N-terminal cross-linking telopeptide of type-I collagen (NTX-I), and free deoxypyridinoline crosslinks (fDPD) at baseline, 1, 12, and 36 months. BMD measurements (hands/spine/hip) were obtained at 3 timepoints. We recruited 62 patients (RA 35; PsA 27). BTM correlated significantly with hand BMD but not with central BMD. Low hand BMD was associated with RA and increased BTM. Following anti-TNF therapy, hip BMD declined while spine and hand BMD were unchanged. Periarticular BMD at proximal interphalangeal (PIP) joints increased while it decreased at metacarpophalangeal joints. Bone ALP increased steadily and was always higher in PsA. PINP and intact osteocalcin increased to a lesser extent, but resorption markers did not change. At baseline, hand BMD was inversely associated with BTM. Bone formation rather than resorption markers better showed the bone response to anti-TNF. Despite a lack of effect on central BMD, the modest effect of anti-TNF on PIP BMD may provide evidence that BTM reflect specifically bone remodeling activity at periarticular sites of inflammation in RA and PsA.

Alleviating effects of morin against experimentally-induced diabetic osteopenia

BackgroundPlant flavonoids are emerging as potent therapeutic drugs effective against a wide range of aging diseases particularly bone metabolic disorders. Morin (3,5,7,20,40-pentahydroxyflavone), a member of flavonols, is an important bioactive compound by interacting with nucleic acids, enzymes and protein. The present study was designed to investigate the putative beneficial effect of morin on diabetic osteopenia in rats.MethodsStreptozotocin (STZ)-induced diabetic model was used by considering 300 mg/dl fasting glucose level as diabetic. Morin (15 and 30 mg/kg) was treated for five consecutive weeks to diabetic rats. Serum levels of glucose, insulin, deoxypyridinoline cross links (DPD), osteocalcin (OC), bone specific alkaline phosphatase (BALP), telopeptides of collagen type I (CTX), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), thiobarbituric acid reactive substance (TBARS) and reduced glutathione (GSH) were estimated. Femoral bones were taken for micro CT scan to measure trabecular bone mineral density (BMD) and other morphometric parameters.ResultsSignificant bone loss was documented as the level of bone turnover parameters including DPD, OC, BALP and CTX were increased in serum of diabetic rats. Morin treatment significantly attenuated these elevated levels. Bone micro-CT scan of diabetic rats showed a significant impairment in trabecular bone microarchitecture, density and other morphometric parameters. These impairments were significantly ameliorated by morin administration. Serum levels of glucose, TBARS, IL-1β, IL-6 and TNF-α were significantly elevated, while the level of insulin and GSH was decreased in diabetic rats. These serum changes in diabetic rats were bring back to normal values after 5 weeks morin treatment.ConclusionThese findings revealed the protective effect of morin against diabetic induced osteopenia. We believed that this effect is through its both the anti-inflammatory and antioxidant properties.

Alteration of proteoglycan sulfation affects bone growth and remodeling

Diastrophic dysplasia (DTD) is a chondrodysplasia caused by mutations in the SLC26A2 gene, leading to reduced intracellular sulfate pool in chondrocytes, osteoblasts and fibroblasts. Hence, proteoglycans are undersulfated in the cartilage and bone of DTD patients. To characterize the bone phenotype of this skeletal dysplasia we used the Slc26a2 knock-in mouse (dtd mouse), that was previously validated as an animal model of DTD in humans.X-rays, bone densitometry, static and dynamic histomorphometry, and in vitro studies revealed a primary bone defect in the dtd mouse model.We showed in vivo that this primary bone defect in dtd mice is due to decreased bone accrual associated with a decreased trabecular and periosteal appositional rate at the cell level in one month-old mice. Although the osteoclast number evaluated by histomorphometry was not different in dtd compared to wild-type mice, urine analysis of deoxypyridinoline cross-links and serum levels of type I collagen C-terminal telopeptides showed a higher resorption rate in dtd mice compared to wild-type littermates. Electron microscopy studies showed that collagen fibrils in bone were thinner and less organized in dtd compared to wild-type mice. These data suggest that the low bone mass observed in mutant mice could possibly be linked to the different bone matrix compositions/organizations in dtd mice triggering changes in osteoblast and osteoclast activities.Overall, these results suggest that proteoglycan undersulfation not only affects the properties of hyaline cartilage, but can also lead to unbalanced bone modeling and remodeling activities, demonstrating the importance of proteoglycan sulfation in bone homeostasis.

Identification of deoxypyridinoline and pyrrole collagen cross-links by Fourier Transform Infrared Spectroscopy

Identification of deoxypyridinoline and pyrrole collagen cross-links by Fourier Transform Infrared Spectroscopy

Markers of Bone Turnover Are Elevated in Patients With Antiretroviral Treatment Independent of the Substance Used

Osteoporosis and bone fractures are correlated to antiretroviral treatment. It is not clear whether some substances comprise greater risks of bone loss than others. We measured pyridinoline, deoxypyridinoline crosslinks, and bone-specific alkaline phosphatase in 113 HIV-positive patients. We compared patients with and without antiretroviral treatment. We then compared patients with versus without tenofovir and patients with protease inhibitor versus nonnucleoside reverse transcriptase inhibitor use. Bone-specific alkaline phosphatase, pyridinoline, and deoxypyridinoline crosslinks were significantly higher in patients with antiretroviral treatment compared with patients without antiretroviral treatment: 24.5 versus 13.04 pg/L (P < 0.001), 82.73 versus 51.93 nmol/mmol (P < 0.001), and 16.56 versus 9.94 nmol/mmol (P < 0.001), respectively. In contrast, no difference was found between patients with and without tenofovir: 25.38 versus 20.02 pg/l (P = 0.1); 79.85 versus 83.95 nmol/mmol (P = 0.64), and 19.12 versus 14.00 nmol/mmol (P = 0.14), respectively. Comparison between patients with protease inhibitor versus nonnucleoside reverse transcriptase inhibitor yielded no difference either: 23.07 versus 27.18 pg/L (P = 0.24), 92.96 versus 80.73 nmol/mmol (P = 0.36), and 18.22 versus 16.39 nmol/mmol (P = 0.55). Markers for bone turnover are higher in treated compared with untreated patients. No difference concerning tenofovir use or protease inhibitor versus nonnucleoside reverse transcriptase inhibitor use could be found.

Prediction of response to growth hormone treatment in pre-pubertal children with growth hormone deficiency

GH therapy response varies substantially among patients. Several models were developed to predict the efficacy of GH therapy in children. To evaluate the accuracy of a growth prediction model using data from an Italian pediatric GH deficiency (GHD) cohort (GeNeSIS, Growth Prediction Sub-study). Open-label, multicenter study in 22 Italian pre-pubertal GH treatment- naïve patients with GHD (8 female, 14 male, 0.5 to 12.2 yr), 18 isolated GHD, 4 multiple pituitary hormone deficiency given recombinat human GH therapy (0.025-0.035 mg/kg/day) for 12 months. Growth prediction was performed, after 3 months of treatment, using baseline data [bone age (BA) and IGF-I], a urinary marker of bone turnover [deoxypyridinoline crosslinks (DPD)] at 4 weeks, and height velocity (HV) at 3 months. Results were expressed as 1st-yr HV using the following equation: 1-yr HV (cm) = 3.543 - (2.337 × BA) - (0.010 × IGF-I) + (0.100 × DPD) + (0.299 × 3-month HV). Predictions were compared to the 1st-yr HV and accuracy was calculated as percentage of the difference between mean calculated HV and the real 1st-yr HV. For females predicted HV was 12.98 ± 4.82 cm/yr and actually was 13.05 ± 3.91 cm/yr after the 1st year; for males predicted HV was 13.95 ± 5.39 cm/yr and actually was 12.93 ± 5.02 cm/yr. In this paediatric Italian cohort with GHD, a growth prediction model seems to be a valid tool to assess 1st-yr response to GH treatment in Italian children.

Association between collagen cross-links and trabecular microarchitecture properties of human vertebral bone

It has been suggested that age-related deterioration in trabecular microarchitecture and changes in collagen cross-link concentrations may contribute to skeletal fragility. To further explore this hypothesis, we determined the relationships among trabecular bone volume fraction (BV/TV), microarchitecture, collagen cross-link content, and bone turnover in human vertebral trabecular bone. Trabecular bone specimens from L2 vertebrae were collected from 51 recently deceased donors (54–95 years of age; 20 men and 30 women). Trabecular bone volume and microarchitecture was assessed by microCT and bone formation, reflected by osteoid surface (OS/BS, %), was measured by 2D histomorphometry. Pyridinoline (PYD), deoxypyridinoline (DPD), pentosidine (PEN) and collagen content in the cancellous bone were analysed by high-performance liquid chromatography. Associations between variables were investigated by Pearson correlations and multiple regression models, which were constructed with BV/TV and collagen cross-links as explanatory variables and microarchitecture parameters as the dependent variables. Results: Microarchitecture parameters were modestly to strongly correlated with BV/TV (r2=0.10–0.71). The amount of mature enzymatic PYD and DPD cross-links were not associated with the microarchitecture, either before or after adjustment for BV/TV. However, there was a positive correlation between PEN content and trabecular number (r=0.45, p=0.001) and connectivity density (r=0.40, p=0.004), and a negative correlation between PEN content and trabecular separation (r=−0.29, p=0.04). In the multiple regression models including BV/TV, age and PEN content was still significantly associated with several of the microarchitecture variables. In summary, this study suggests a link between trabecular microarchitecture and the collagen cross-link profile. As PEN reflects non-enzymatic glycation of collagen and generally increases with bone age, the association between PEN and trabecular architecture suggests that the preserved trabeculae may contain mainly old bone and have undergone little remodeling. Thus, vertebral fragility may not only be due to alterations in bone architecture but also to modification of collagen cross-link patterns thereby influencing bone's mechanical behavior.

Longitudinal study of urinary hydroxy-pyridinium cross-links and growth in healthy infants: higher values with breastfeeding and after daytime sleep.

Urinary pyridinoline and deoxypyridinoline crosslinks (crosslink) are excreted when bone is resorbed. The aims of this study in healthy infants were to determine whether crosslinks a) could predict growth velocity, b) are variable due to circadian rhythm, and c) differ in infants who were either breast-fed or formula-fed. In 78 healthy infants (48 male; 30 female) urine samples were collected and anthropometric measurements were taken at 2, 3, 4, 5, 6, 8, 10 and 12 months of age. In addition, a total of 25 samples were collected during the day (0700-2000) in 5 of the infants to determine circadian rhythm of crosslink excretion. Crosslink excretion decreased (p < 0.001) with age between 2 and 12 months. Pyridinoline excretion showed a significant, but weak correlation (r > or = 0.21; p < 0.05) with linear growth velocity and weight velocity in the subsequent month until 6 months of age, and no correlation thereafter. Infants studied for circadian rhythm showed a 63% greater (p < 0.05) rate of pyridinoline excretion after a nap as compared to the 13-hour mean value. In a subset of infants whose energy intake was exclusively from breast milk (BF, n = 23) or formula (FF, n = 10), crosslink excretion was greater in BF infants at 3 months of age (p < 0.05). The correlations between crosslink excretion and growth parameters indicate that crosslinks may be useful as a marker of growth in infant populations. However sources of variation in crosslink excretion, such as circadian rhythm and diet may limit their utility to predict growth in an individual infant. These factors should be considered in future studies examining markers of bone turnover in infants.

Milk ribonuclease-enriched lactoferrin induces positive effects on bone turnover markers in postmenopausal women

Current treatments for postmenopausal osteoporosis suffer from side effects. Safe and natural milk proteins, ribonuclease, and lactoferrin promote formation of new capillaries and bone formation. A ribonuclease-enriched lactoferrin supplement studied here, demonstrates significant reduction in resorption and increase in formation, towards restoring the balance of bone turnover within 6 months. Osteoporosis, a major health issue among postmenopausal women, causes increased bone resorption and reduced bone formation. A reduction in angiogenesis could also contribute to this imbalance. Current treatments such as hormone replacement therapy and bisphosphonates have drawbacks of severe side effects. Milk ribonuclease (RNase) is known to promote angiogenesis and lactoferrin (LF) to stimulate bone formation by osteoblasts. We examine the effect of ribonuclease-enriched lactoferrin supplement on the bone health of postmenopausal women. A total of 38 healthy, postmenopausal women, aged 45 to 60 years were randomized into placebo or RNAse-enriched-LF (R-ELF) supplement groups. The bone health status was monitored by assessing bone resorption markers, serum N-telopeptides (NTx), and urine deoxypyridinoline (Dpd) crosslinks and serum bone formation markers, bone-specific alkaline phosphatase (BAP), and osteocalcin (OC). R-ELF supplementation demonstrated a decrease in urine Dpd levels by 14% (19% increase for placebo) and serum NTx maintained at 24% of the baseline (41% for placebo), while serum BAP and OC levels showed a 45% and 16% elevation (25% and 5% for placebo). R-ELF supplementation demonstrated a statistically significant reduction in bone resorption and increase in osteoblastic bone formation, to restore the balance of bone turnover within a short period.

Peptide Bound Hypohydroxyprolinuria in Handigodu Disease: A Familial Syndrome of Spondylo Epi(meta)physeal Dysplasia

Handigodu Disease (HD) is disorder of the osteoarticular system prevalent in few villages of two districts of the state Karnataka in southern India. 24 hrs urinary excretions of proline (Pro) and 4-hydroxyproline (Hyp) were analyzed by HPLC. Decreased peptide bound Hyp excretions (μmole/24 hrs) were found in patient group when compared with controls (Nonaffected; 113.02 ± 67.96, Type-I; 36.22 ± 20.76, Type-II; 45.74 ± 14.95, Type-III; 40.46 ± 22.68) and without significant difference in Pro excretions. Significant increased peptide bound Pro to Hyp ratio were found in patient group compared to control (Nonaffectedn= 63: 2.02 ± 1.65, Type-In= 18: 3.144 ± 1.42, Type-IIn= 28: 4.21 ± 1.95, Type-IIIn= 8: 8.60 ± 6.55). 24 hrs urinary excretions of deoxypyridinoline (DPD) crosslinks were found without significant difference among affected and control, hence HD ruled out from general bone reduction. These results suggest hypohydroxyprolinuria may be because of reduced bone turnover or defective hydroxylation of prolyl residues during post translational modification of collagen biosynthesis.