Ratio Of Pyridinoline Research Articles

Impact microindentation measurements correlate with cortical bone material properties measured by Fourier transform infrared imaging in humans.

Bone Material Strength index (BMSi) measured by Impact Microindentation is generally lower in subjects with fragility fractures independently of BMD values. We recently reported that in humans, BMSi values are strongly associated with material properties of subperiosteal mineralized bone surface (local mineral content, nanoporosity, pyridinoline content). In the present study we investigated the relationship of BMSi with material properties of the whole bone cortex, by analyzing thin sections of iliac crest biopsies (N=12) from patients with different skeletal disorders and a wide range of BMD with or without fractures, by Fourier transform infrared imaging (FTIRI). The calculated parameters were: i) mineral and organic matrix content and their ratio (MM), ii) mineral maturity/crystallinity (MMC) and iii) the ratio of pyridinoline (Pyd) and divalent collagen cross-links (XLR). Results were expressed as images, which were converted to histogram distributions. For each histogram the characteristics recorded were: mean value, mode (most often occurring value), skewness, and kurtosis and their association with BMSi values was examined by correlation analysis. BMSi values were significantly correlated only with MM mean and mode values (r=0.736, p=0.0063, and r=0.855, p=0.0004, respectively), and with XLR mode values (r=-0.632, p=0.0274). The results of the present study demonstrate that BMSi values are strongly associated with MM, a metric that corrects the mineral content for the organic matrix content, and may also depend on organic matrix quality. These and our previous observations strongly suggest that BMSi assesses material properties of cortical bone.

Accelerated bone ingrowth by local delivery of Zinc from bioactive glass: oxidative stress status, mechanical property, and microarchitectural characterization in an ovariectomized rat model

BackgroundSynthetic bone graft substitutes such as bioactive glass (BG) material are developed in order to achieve successful bone regeneration. Zn plays an important role in the proper bone growth, development, and maintenance of healthy bones.AimsThis study aims to evaluate in vivo the performance therapy of zinc-doped bioactive glass (BG-Zn) and its applications in biomedicine.MethodsFemale Wistar rats were ovariectomized. BG and BG-Zn were implanted in the femoral condyles of Wistar rats and compared to that of control group. Grafted bone tissues were carefully removed to evaluate the oxidative stress status, histomorphometric profile, mechanical property, and mineral bone distribution by using inductively coupled plasma optical emission spectrometry.ResultsA significant decrease of thiobarbituric acid–reactive substances was observed after BG-Zn implantation. Superoxide dismutase, catalase (CAT), and glutathione peroxidase (GPx) activities significantly increased in ovariectomized group implanted with Zinc-doped bioactive glass (OVX-BG-Zn) as compared to ovariectomized group implanted with bioactive glass (OVX-BG). An improved mechanical property was noticed in contact of OVX-BG-Zn (39±6 HV) when compared with that of OVX-BG group (26±9 HV). After 90 days of implantation, the histomorphometric analysis showed that trabecular thickness (Tb.Th) and trabecular number (Tb.N) were significantly increased with 28 and 24%, respectively, in treated rats of OVX-BG-Zn group as compared to those of OVX-BG groups. Trabecular separation (Tb.Sp) and trabecular bone pattern factor (TBPf) were significantly decreased in OVX-BG-Zn group with 29.5 and 54% when compared with those of OVX-BG rat groups. On the other hand, a rise in Ca and P ion concentrations in the implanted microenvironment was shown and lead to the formation/deposition of Ca-P phases. The ratio of pyridinoline [Pyr] to dihydroxylysinonorleucine [DHLNL] cross-links was normalized to the control level.ConclusionOur findings suggested that BG-Zn might have promising potential applications for osteoporosis therapy.

Effects of bone anabolic agents on bone ultrastructure

BackgroundCurrently, several effective anti-osteoporotic drugs areavailable, and their mechanisms of action are well known,albeit widely varying depending on the nature of the drugsinvolved. This paper addresses the following questions:Firstly, to what extent do these molecules and theirmechanisms of action accountfor their antifracture efficacy?Secondly, it is known that changes in the values ofintermediate parameters (BMD, bone remodelling markers)during treatment only partially account for the antifractureefficacy of these drugs.Various data suggest that the effect of anti-osteoporoticdrugs onbonemicroarchitecture is alsoan important factor totakeintoaccount.Recentfindingssuggestthattheeffectofthedrugs involved on bone ultrastructure plays a specific role.Thiseffectisoftenverydifferentdependingonthemechanismof action of the molecules in question (bone resorptioninhibitors, bone formation agents). The purpose of this paperis to evaluate the effect of bone anabolic agents on boneultrastructure. The effects of parathormone—both intactparathormone (PTH 1-84) and teriparatide (PTH 1-34)—andstrontium ranelateinparticularare considered.Asonlyalittledata is currently available in this field, we will be referring toanimalstudiesandtothefewstudiesundertakenusinghumanbone biopsies.IntroductionWith regards the ultrastructural characteristics of bonetissue, not only the mineral phase needs to be studied butalso the organic phase. Mineralisation process takes place attissue level whereas the study of bone mineral will help oneto assess the characteristics of the apatite crystal whichplays a strong role both in bone homeostasy and bonemetabolism.PTHThe increase in BMD observed in patients treated withteriparatide (TPT) accounts for no more than 40% of themolecule's antifracture efficacy [1]. It seems that TPT canalso modify some intrinsic properties of bone tissue, i.e.degree of bone mineralisation, mineral crystallinity and sizeand degree of maturation of collagen crystals. The latterproperty can be determined by measuring the ratio ofpyridinoline (pyr) to dehydro-dihydroxylysino-norleucine(deH-DHLNL).Paschalis et al. [2] analysed 61 pairs of bone biopsies(BB) taken from patients who had received either aplacebo or TPT. The interval between two biopsies was12 months in 21 cases and 18 months in the 40 remainingcases. The first group were as follows: placebo,n=8; TPT20μg, n=7; TPT 40μg, n=6. In the second group, 16patients received the placebo, 14 received a 20-μg/daydose of TPT and ten received a 40-μg/day dose of TPT.Biopsies from 15 patients from each group were selectedfor analysis using Fourier transformed infrared imaging(FTIRI). Seven biopsies were excluded due to insufficientquality. In all, 38 BB pairs were analysed using the FTIRImethod. The group of BB pairs were as follows: placebo,

Spectroscopically Determined Collagen Pyr/deH-DHLNL Cross-Link Ratio and Crystallinity Indices Differ Markedly in Recombinant Congenic Mice with Divergent Calculated Bone Tissue Strength

Whole bone strength can be partitioned into structural and material components. In three-point bending tests of 6-month-old female humeri from the HcB/Dem recombinant congenic series, strains HcB/8 and HcB/23 differed markedly in calculated failure stress but not ash percentage. Fourier transform infrared spectroscopic imaging was used to determine whether differences in the ratio of pyridinoline (pyr; nonreducible) to dehydrodihydroxynorleucine (de-DHLNL; reducible) collagen cross-links (XLR), mineral crystallinity, or spatial ordering could account for the strains' differing biomechanical performance. HcB/8 had significantly higher XLR and significantly higher crystallinity than HcB/23. XLR and crystallinity were highly and similarly correlated in both strains. There were no significant differences between the strains' one-dimensional spatial correlation functions, suggesting no difference in short-range order between them. The strong correlation between XLR and crystallinity reflects the interdependence of the protein and mineral elements of bone. The data illustrate the importance of material properties in addition to mineral quantity to bone tissue strength.

Changes in collagen cross-link ratios in bone and urine of guinea pigs fed graded dietary vitamin C: a functional index of vitamin C status

Vitamin C is essential for the hydroxylation of lysine in collagen. The resulting hydroxylysine residues, together with the precursor lysine residues, are then incorporated into the stable collagen cross-links: pyridinoline and deoxypyridinoline. A reduction in lysine hydroxylation, resulting from an inadequate supply of vitamin C, might decrease the ratio of the pyridinoline crosslinks to the deoxypyridinoline crosslinks. This hypothesis was tested in a guinea pig model, using a purified diet providing vitamin C in the following amounts: (a) 0.5 mg/day; (b) 1 mg/day; (c) 5 mg/day; (d) 0.25% w/v in the diet (providing 49 mg/day); (e) 1.0% w/v (providing 205 mg/day); or (f) 5.0% w/v (providing 1128 mg/day). Weanling male guinea pigs each received one of these diets for 46 days, after which their tissue vitamin C concentrations, and the concentrations of hydroxyproline, pyridinoline, and deoxypyridinoline in bone, and of creatinine, pyridinoline, and deoxypyridinoline in urine, were measured. The ratio of pyridinoline to deoxypyridinoline in bone collagen and in urinary collagen fragments decreased significantly as vitamin C depletion became more severe. Animals receiving the higher intakes of vitamin C grew more rapidly than did those receiving the lower intakes, but the relationship between vitamin C intake and the collagen crosslinks ratio remained highly significant, even after adjusting for intergroup differences in growth rates. Thus, the ratio between the two collagen crosslinks could provide a specific and sensitive functional index of vitamin C in animals and man. This is an important goal, in view of the need to be able to define optimum intakes of vitamin C.

Seasonal differences in biochemical parameters of bone remodelling.

To compare bone remodelling parameters in late autumn and early spring in 20 post-menopausal women. The parameters measured were serum osteocalcin and its apparent degree of carboxylation (measured by hydroxyapatite binding), total and bone specific alkaline phosphatase and urinary bone resorption markers, (pyridinoline and deoxypyridinoline). Serum osteocalcin concentrations were lower in autumn than in spring but the degree of carboxylation was similar. Total and bone specific alkaline phosphatase activities in serum were higher in autumn than in spring. These results support previous observations. However, notable and previously unreported changes in urinary bone resorption markers were observed. Pyridinoline concentrations were lower and deoxypyridinoline higher in autumn compared with spring. The ratio of pyridinoline:deoxypyridinoline was therefore very different between the seasons. The results clearly demonstrate that seasonal changes in these variables of bone remodelling must be taken into consideration when designing, reporting or analysing studies of bone metabolism in vivo.