Pyridinoline Cross-links Research Articles

Plasma Levels of C-Telopeptide Pyridinoline Cross-Links of Type I Collagen and Osteocalcin in Chronic Periodontitis

This study was planned to investigate whether chronic periodontitis patients exhibit different plasma concentrations of C-telopeptide pyridinoline cross-links of type I collagen (ICTP) and osteocalcin (OC) compared to the clinically healthy controls. Before initiation of any periodontal intervention, plasma samples and full-mouth clinical periodontal recordings were obtained from 58 otherwise healthy patients with chronic periodontitis and also from 47 systemically and periodontally healthy control subjects. Plasma ICTP levels were determined by radioimmunoassay and OC levels by enzyme-linked immunosorbent assay. Data were tested statistically using t test and ANOVA. The healthy control group exhibited significantly lower values in all clinical periodontal measurements (P < 0.001). There were no significant differences between the study groups in plasma ICTP and OC levels (P > 0.05). Within the limits of this study, it may be suggested that plasma levels of ICTP and OC may not provide distinguishing data between chronic periodontitis patients and clinically healthy subjects.

Differential regulation of immature articular cartilage compressive moduli and Poisson’s ratios by in vitro stimulation with IGF-1 and TGF-β1

Mechanisms of articular cartilage growth and maturation have been elucidated by studying composition-function dynamics during in vivo development and in vitro culture with stimuli such as insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta 1 (TGF-β1). This study tested the hypothesis that IGF-1 and TGF-β1 regulate immature cartilage compressive moduli and Poisson’s ratios in a manner consistent with known effects on tensile properties. Bovine calf articular cartilage from superficial-articular (S) and middle-growth (M) regions were analyzed fresh or following culture in medium with IGF-1 or TGF-β1. Mechanical properties in confined (CC) and unconfined (UCC) compression, cartilage matrix composition, and explant size were assessed. Culture with IGF-1 resulted in softening in CC and UCC, increased Poisson’s ratios, substantially increased tissue volume, and accumulation of glycosaminoglycan (GAG) and collagen (COL). Culture with TGF-β1 promoted maturational changes in the S layer, including stiffening in CC and UCC and increased concentrations of GAG, COL, and pyridinoline crosslinks (PYR), but little growth. Culture of M layer explants with TGF-β1 was nearly homeostatic. Across treatment groups, compressive moduli in CC and UCC were positively related to GAG, COL, and PYR concentrations, while Poisson’s ratios were negatively related to concentrations of these matrix components . Thus, IGF-1 and TGF-β1 differentially regulate the compressive mechanical properties and size of immature articular cartilage in vitro. Prescribing tissue growth, maturation, or homeostasis by controlling the in vitro biochemical environment with such growth factors may have applications in cartilage repair and tissue engineering.

The application of bone collagen metabolism markers in bone metastases of breast carcinoma

Objective To evaluate the values of using specific osteolytic bone metabolic markers such as serum type Ⅰ collagen carboxyterminal telopeptide(sICTP),urinary nitrogen-terminal cross-linked telopeptides of type Ⅰ collagen(uNTx),urinary pyridinoline crosslinks(uPYD)in bone metastasis of breast cancer.Methods The levels of slCTP,uNTx and uPYD in 72 patients with breast cancer were measured using ELISA.The sensitivity and specificity of diagnostic value in bone metastasis of breast cancer were cal-culated.Seventy-two patients with breast carcinoma were divided into two groups depending on the presence of bone metastasis according to bone scan findings and confirmed by X-ray and/or CT.The level of bone markers was compared between the two groups.Further relation between bone metabolic marker and tumor behavior in the patients with bone metastases was studied detailedly.Results The levels of all bone mark-ers in patients with bone metastasis were significantly higher than those of in ones without bone metastasis(P＜0.05).A significant correlation was seen between each two markers(r＞0.5,P＜0.01).The sensitivity and specificity was 72.00% and 83.33% in uNTx; 80.56% and 80.56% in uPYD; 80.56% and 97.22% in sICTP,respectively.Evident differences were seen between the extent of skeletal infiltration and the levels of the three biomarkers(P＜0.05).The correlations were seen between the levels of the three biomarkers and the risk of occurrence of bone metastasis(P＜0.05).Conclusion The measurement of sICTP,uNTx and uPYD are of significant utility as biochemical markers of bone metastasis in patients with breast cancer and can be used to achieve a timely diagnosis for bone metastasis of breast cancer. Key words: Breast neoplasms; Bone neoplasms; Neoplasm metastasis; Biological markers; Collagen type Ⅰ

Quantitative measurement of mature collagen cross-links in human carotid artery plaques

While there is an appreciable understanding of the importance of collagen breakdown in contributing to atherosclerotic plaque vulnerability and rupture, little is known about changes in collagen maturation in the atherosclerotic plaque. This is achieved through the formation of the covalent intermolecular cross-links pyridinoline (Pyd) and deoxypyridinoline (Dpd). In this study we collected carotid endarterectomy specimens from patients and undertook (i) histological assessment of collagen and inflammatory cell distribution and (ii) biochemical analysis of total collagen and cross-link content. Greater collagen deposition, increased presence of CD68 positive cells and an increased Pyd:Dpd ratio (an indicator of lysyl hydroxylase (LH-1) activity) were found in plaque versus normal vascular tissue. These findings are the first measurements of Pyd and Dpd cross-links in normal and atherosclerotic vascular tissue. The observed differences in cross-links in the plaque may adversely affect tensile strength and may have relevance to the mechanisms underlying rupture of vulnerable plaques.

Effects of smoking on salivary C-telopeptide pyridinoline cross-links of type I collagen and osteocalcin levels

Aim This study was planned to investigate whether smoker patients with inflammatory periodontal disease exhibit different salivary concentrations of C-telopeptide pyridinoline cross-links of type I collagen (ICTP) and osteocalcin (OC) compared to the non-smoker and/or ex-smoker counterparts. Methods Whole saliva samples, full-mouth clinical periodontal recordings were obtained from 67 otherwise healthy patients with inflammatory periodontal disease. According to self-reports there were 34 smokers, 22 non-smokers and 11 ex-smokers. Salivary cotinine, ICTP and OC levels were determined by enzyme-linked immunoassays. Results Salivary cotinine measurements confirmed self-reports about smoking. Smoker patients revealed significantly higher plaque index values than non-smokers ( p < 0.05). Bleeding on probing values were significantly lower in smoker group than ex-smoker group ( p < 0.05). There was no significant difference between the study groups in salivary ICTP levels ( p > 0.05). OC levels in smoker group was significantly lower than the other groups ( p < 0.001). Salivary ICTP levels correlated negatively with number of teeth present ( p < 0.05), positively with bleeding on probing ( p < 0.01). Salivary OC levels correlated negatively with years smoked ( p < 0.01). Conclusions Within the limits of this study, smoking seems to suppress salivary osteocalcin level but ICTP levels seem not to be affected by smoking status. This suppression in OC levels may be one mechanism of deteriorating effects of smoking on periodontal health.

Collagen cross-links as a determinant of bone quality: a possible explanation for bone fragility in aging, osteoporosis, and diabetes mellitus

Collagen cross-linking, a major post-translational modification of collagen, plays important roles in the biological and biomechanical features of bone. Collagen cross-links can be divided into lysyl hydroxylase and lysyloxidase-mediated enzymatic immature divalent cross-links,mature trivalent pyridinoline and pyrrole cross-links, and glycation- or oxidation-induced non-enzymatic cross-links(advanced glycation end products) such as glucosepane and pentosidine. These types of cross-links differ in the mechanism of formation and in function. Material properties of newly synthesized collagen matrix may differ in tissue maturity and senescence from older matrix in terms of crosslink formation. Additionally, newly synthesized matrix in osteoporotic patients or diabetic patients may not necessarily be as well-made as age-matched healthy subjects. Data have accumulated that collagen cross-link formation affects not only the mineralization process but also microdamage formation. Consequently, collagen cross-linking is thought to affect the mechanical properties of bone. Furthermore,recent basic and clinical investigations of collagen cross-links seem to face a new era. For instance, serum or urine pentosidine levels are now being used to estimate future fracture risk in osteoporosis and diabetes. In this review, we describe age-related changes in collagen cross-links in bone and abnormalities of cross-links in osteoporosis and diabetes that have been reported in the literature.

9040 Short term (2-month) survival prognostication in newly-diagnosed patients with Non-Small Cell Lung Cancer

This study was planned to investigate whether smoker patients with inflammatory periodontal disease exhibit different salivary concentrations of C-telopeptide pyridinoline cross-links of type I collagen (ICTP) and osteocalcin (OC) compared to the non-smoker and/or ex-smoker counterparts.Whole saliva samples, full-mouth clinical periodontal recordings were obtained from 67 otherwise healthy patients with inflammatory periodontal disease. According to self-reports there were 34 smokers, 22 non-smokers and 11 ex-smokers. Salivary cotinine, ICTP and OC levels were determined by enzyme-linked immunoassays.Salivary cotinine measurements confirmed self-reports about smoking. Smoker patients revealed significantly higher plaque index values than non-smokers (p < 0.05). Bleeding on probing values were significantly lower in smoker group than ex-smoker group (p < 0.05). There was no significant difference between the study groups in salivary ICTP levels (p > 0.05). OC levels in smoker group was significantly lower than the other groups (p < 0.001). Salivary ICTP levels correlated negatively with number of teeth present (p < 0.05), positively with bleeding on probing (p < 0.01). Salivary OC levels correlated negatively with years smoked (p < 0.01).Within the limits of this study, smoking seems to suppress salivary osteocalcin level but ICTP levels seem not to be affected by smoking status. This suppression in OC levels may be one mechanism of deteriorating effects of smoking on periodontal health.

Metabolic bone disease in HIV infection

HIV mainly replicates in CD4þ T lymphocytes andmonocyte/macrophages causing severe immunologicalimpairment. In addition to the immune system, HIVinfection affects tissues and organs such as kidney, liver,the central nervous system, heart and bone showing acomplex pathogenesis [1].The advent and widespread use of highly activeantiretroviral therapy (HAART) in the last two decadeshasled toa markedimprovementinthe treatmentofHIVdisease even though viral infection cannot be eradicatedbecause HAART does not completely eliminate the viralreservoirs [2]. HAART has dramatically changed thecourseofHIVinfection froma fatalinfectiontoachronicand relatively manageable disease. The increased lifeexpectancyofHIVpatientsandtheeffectsofHAARThavechanged the management of HIV infection. Nowadaysmedical treatment is no longer focused solely on HIVinfection, opportunistic diseases and monitoring immunederangement, but also includes the control of metabolic,cardiovascular, liver, bone and kidney complications. Inparticular, bone alterations have been observed in thecourse of HIV disease representing a pivotal clinicalprobleminthemanagementofHIVpatientsespeciallyforapossible development of bone fractures [3]. The majorbonelesionsdetectableinHIVpatientsarerelatedtobonedemineralization (osteopenia/osteoporosis and osteoma-lacia) and osteonecrosis ([4] for a review).This report will discuss the pathogenesis, diagnosis andtreatment of major bone complications represented bybone demineralization diseases during HIV infection andHAART treatment.

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.

The molecular mechanism of photodynamic therapy to fibrosis: Regulation on the pyridinoline cross-link formation in collagen

Fibrotic processes in tissues are characterised by an excessive accumulation of collagen containing increased levels of pyridinoline cross-links, which has been taken as an important criterion to diagnose the fibrosis. Hypocrellin B (HB) is a natural photosensitizer with excellent photodynamic activity but very low dark-toxicity. In the current work, main purpose was to clarify if photodynamic action of HB could be applied to regulating the level of pyridinoline cross-link in collagen. To use gelatin as a model collagen, it was observed that the pyridinoline cross-link formation was effectively degraded by HB photodynamic action in the gelatin, suggesting the level of pyridinoline cross-link formation in collagen may be photodynamically regulated to a normal level. Furthermore, mechanism of the photodynamic action of HB was studied.

TIA Nuclear Proteins Regulate the Alternate Splicing of Lysyl Hydroxylase 2

Synthesis of collagen, a major component of the extracellular matrix, is increased dramatically in fibrotic conditions such as scleroderma. This overaccumulation of collagen is associated with increased pyridinoline cross-links. These cross-links are derived by the action of the alternatively spliced long form of lysyl hydroxylase 2 (LH2), a collagen telopeptide LH. As LH2 (long) is reported to be overexpressed in scleroderma fibroblasts, the regulation of LH2 splicing suggests an important step in controlling fibrosis. Using an LH2 minigene, we have compared the regulation of the alternative splicing pattern of LH2, both endogenously and in the minigene, by the RNA-binding splicing proteins TIA-1 and TIAL1 (T-cell-restricted intracellular antigens). A decrease in the ratio of LH2 (long) to LH2 (short) was observed in fibroblasts from TIAL1 knockout mice, and in HEK293 cells knocked down for TIA-1 and TIAL1. As a corollary, overexpression of TIA-1/TIAL1 in HEK293 cells resulted in an increase in LH2 (long) minigene transcripts, accompanied by a decrease in LH2 (short). In scleroderma fibroblasts, a double TIA-1/TIAL1 knockdown reduced the ratio of LH2 (long) to LH2 (short) by over fivefold compared to controls. Identification of these TIA regulatory factors therefore suggests a tool to manipulate cellular LH2 levels in scleroderma so that potential intervention therapies may be identified.

Bone Resorption in Kidney Transplant Recipients

Early diagnosis of persistent hyperparathyroidism (HP) following kidney transplantation may prevent worsening of osteodystrophy and potential damage to the graft. We evaluated the utility of collagen pyridinoline (PYD) and deoxypyridinoline (DPD) urinary cross-links beyond the common HP markers to evaluate 70 selected stable recipients between 1997 and 2006 who were divided into 2 group depending on the immunosuppressive protocol. All patients showed elevated levels of urinary cross-links even though calcemia and phosphoremia values were normal. Their mean creatinine level was slightly increased. Data were assessed as mean values ± SD. All variables underwent a correlation matrix analysis and a stepwise regression, with posttransplant intact parathyroid hormone (iPTH) as the dependent variable and other variables as regressors. A statistically significant correlation was observed between PYD and alkaline phosphatase (ALP; P = .0026, r = .41); PYD and DPD ( P = .015, r = .34); pre- and posttransplant iPTH ( P = .024, r = .31); and creatinine and ALP ( P = .024, r = .31). Taking the groups separately, there were significant correlations between PYD and ALP ( P = .0076, r = .42); PYD and DPD ( P = .017, r = .38); ALP and posttransplant iPTH ( P = .038, r = .33); osteocalcin (OC) and posttransplant iPTH ( P = .048, r = .32); and pre- and posttransplant iPTH ( P = .019, r = .37) among subjects in the first group, whereas subjects in the second group showed a correlation between posttransplant iPTH and age at transplantation ( P = .032, r = .61). In conclusion, we showed that urinary cross-links may be helpful to reveal bone resorption in kidney recipients when usual bone metabolism parameters do not demonstrate hyperparathyroidism.

Possible impact of inflammatory status on C‐telopeptide pyridinoline cross‐links of Type I collagen and osteocalcin levels around oral implants with peri‐implantitis: a controlled clinical trial

Detection of progression level of peri-implantitis may help in the prevention of oral implant failure. C-telopeptide pyridinoline crosslinks of Type I collagen (ICTP) and osteocalcin (OC) are specific markers of bone turnover and bone degradation. Determination of the ICTP and OC levels in the peri-implant sulcus fluid (PISF) may predict the metabolic and/or inflammatory changes in the peri-implant bone. The aim of this clinical study was to evaluate ICTP and OC levels in the PISF for oral implants with and without peri-implant bone destruction and correlate these levels with the traditional clinical peri-implant parameters (probing depth, plaque index, gingival index and gingival bleeding time index) and radiographic bone level measurements. Fifteen patients with 30 peri-implant sites with bone destruction (radiographic bone loss) and health were included. Clinical parameters were measured and PISF was collected from the sites. Peri-implant sulcus fluid ICTP and OC levels were detected by radioimmunoassay technique from PISF samples. All clinical parameters demonstrated a significant increase in peri-implantitis sites compared with healthy sites. The PISF volume of the peri-implantitis sites was also significantly higher than of the healthy peri-implant sites. Although not statistically significant, a trend of increase was demonstrated in ICTP PISF samples sampled from peri-implantitis sites compared with healthy sites. A significant increase was noticed for OC PISF level in peri-implantitis sites compared with healthy ones. As well as peri-implant clinical measurements, volumetric changes at PISF may be counted as an important clinical parameter to distinguish the bone destruction sites from healthy sites around oral implants.

Comparison of the bone protective effects of an isoflavone-rich diet with dietary and subcutaneous administrations of genistein in ovariectomized rats

Administration of the isoflavone genistein (GEN) has been described to result in bone protection but also to induce uterotrophic responses. To compare bone protective effects of GEN with an isoflavone-rich diet (IRD) and to further elucidate molecular mechanisms involved in bone-protection, ovariectomized rats (OVX) received either a diet low in isoflavone content (IDD) enriched with GEN (42 mg kg −1 b.wt d −1) (GEN d), an IRD (14 mg kg −1 b.wt d −1 GEN, 14 mg kg −1 b.wt d −1 daidzein) or were treated subcutaneously (s.c.) with GEN (10 mg kg −1 b.wt d −1) (GEN sc) for 12 weeks. Intact (SHAM), vehicle treated OVX animals and those substituted with 17β-estradiol (2 μg kg −1 b.wt d −1) (E 2), served as controls. OVX-induced bone loss could be antagonized in E 2, GEN sc, GEN d and IRD groups. Uterine wet weight (UWW) was only stimulated in E 2 and GEN sc animals. Serum biomarkers of bone-formation (osteocalcin, osteopontin) and bone-resorption (telopeptides of collagen type I, pyridinoline cross-links) were elevated in OVX compared to SHAM and E 2 animals. Feeding IRD stimulated bone-formation and inhibited bone-resorption, whereas s.c. or dietary administration of GEN only resulted in a stimulation of bone-formation. The results of the present study indicate that in contrast to s.c. administration, dietary intake of GEN resulted in bone protection without stimulation of UWW. Dietary intake of isoflavones by an IRD also did not result in a stimulation of UWW, yet IRD appeared to be more effective in bone protection than administration of pure GEN.

Bone Remodeling Biomarkers of Periodontal Disease in Saliva

Tumor necrosis factor-alpha (TNF-alpha), C-telopeptide pyridinoline cross-links of type I collagen (ICTP), and receptor activator of nuclear factor-kappa B ligand (RANKL) have been associated with bone remodeling and periodontal tissue destruction. This study evaluated the level of these biomarkers in saliva with respect to periodontal disease status. Levels of TNF-alpha in unstimulated whole saliva of 74 adults (35 subjects with moderate to severe periodontal disease and 39 healthy controls) and salivary levels of RANKL and ICTP of a subset of 21 subjects and 21 matched controls were examined using enzyme immunosorbent assays in a case-control clinical study. Salivary levels of TNF-alpha were detected in all subjects, whereas levels of ICTP and RANKL were detected in only a minority of subjects. Mean salivary levels of TNF-alpha were significantly higher in individuals with periodontal disease (mean: 4.33 pg/ml) than in controls (mean: 2.03 pg/ml; P = 0.02), with a maximum level (27.96 pg/ml) observed in periodontitis. Subjects with salivary TNF-alpha levels above a threshold of 5.75 pg/ml (i.e., two standard deviations above the mean of the controls) had significantly more sites with bleeding on probing, probing depths >/=4 mm, and attachment loss > or =2 mm (P < or =0.01). Salivary levels of TNF-alpha were elevated in patients who had clinical indicators of periodontitis, suggesting that this biomarker may serve in a panel of salivary biomarkers that could facilitate the screening, diagnosis, and management of periodontal disease.

Characterization of bone mineral density in male-to-female transsexuals receiving treatment for reassignment surgery: 15 years of follow-up

Background Cross-sex hormone treatment in male-to-female (M2F) transsexuals appears reasonably safe. Little is known about its long-term use. The aim of our study was to evaluate the effect of long-term high dose estrogens, plus the antiandrogen cyproterone acetate, on bone composition and on biochemical/hormonal parameters in M2F transsexuals. Methods A retrospective analysis was performed on 45 young M2Fs (mean age 39.5 years; body mass index (BMI) = 22) receiving estrogens (previously 100 μg ethinyl estradiol, now 2–4 mg oral estradiol valerate/day or 100 μg transdermal estradiol/day) plus the antiandrogen cyproterone acetate 100 mg/day. Data were retrieved from 20 subjects after reassignment surgery (mean hormonal treatment duration 15.6 years). A complete hormonal and biochemical assessment, as well as bone biochemical markers (parathyroid hormone (PTH), calcium, phosphorus, alkaline phosphatase and plasma pyridinoline crosslinks), were evaluated. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA). Results All subjects had suppressed serum testosterone levels (mean = 0.57 nmol/l), whereas serum estradiol levels were within the supraphysiological range (mean = 880 pmol/l). A mild osteopenia at both lumbar spine and femoral neck was observed in 15 out of the 20 (75%) M2Fs (BMD = 0.89 ± 0.14 (mean ± standard deviation (SD)) g/cm 2 versus 1.1 ± 0.09, p < 0.001; lumbar T-score = −1.39 ± 0.84 versus 0.5 ± 1.10, p < 0.0005; femoral T-score = −1.12 ± 0.76 versus 0.08 ± 1.00, p < 0.05, respectively). No differences in plasma crosslink levels or in hormonal and biochemical parameters were found between subjects. Conclusions Our results indicate that cross-sex hormone treatment of M2Fs, independently of serum testosterone levels, seems acceptably safe over a median treatment period of 15 years in a consistent population of subjects. A protective role for estrogens on bone seems to be present in a minority of subjects.

Impaired pyridinoline cross-link formation in patients with osteogenesis imperfecta

Patients with osteogenesis imperfecta (OI) show various degrees of bone fragility. Nevertheless, details of the mechanisms causing bone fragility remain unclear. We hypothesized that differences in pyridinoline cross-link formation at the N-and C-termini in type I collagen molecules partly contribute to bone fragility of OI. To verify this hypothesis, urinary N and C terminal telopeptides of type I collagen (uNTx and ubetaCTx, respectively) and urinary hydroxyproline (uHyp) were measured using second morning void urine samples obtained from OI patients and healthy control children. Ratios of uNTx and ubetaTx to uHyp (uNTx/uHyp and ubetaCTx/uHyp, respectively) of OI patients and healthy normal control children were analyzed. Ratios of uNTx to ubetaCTx (uNTx/ubetaCTx) were also analyzed. In OI patients, uNTx and ubetaCTx were lower than in healthy control children. Also, uNTx/uHyp and ubetaCTx/uHyp were significantly lower than in healthy children. Among OI patients, uNTx/uHyp and uNTx/ubetaCTx of type III OI were significantly lower than of either type I or type IV OI. These results show that pyridinoline cross-link formation is lower than in healthy control children and that pyridinoline cross-link formation at the N-and C-termini in type I collagen molecules might be differently disrupted in OI patients according to the severity of OI.

Bone density and bone metabolism regulated by vitamin D receptor allele polymorphism in a German study sample

It has been reported that the spinal bone density is associated with vitamin-D-receptor (VDR) gene polymorphisms. The results of recent studies have been contradictory concerning the predictive power for low bone mineral density (BMD). Regional population-specific influences have been found to affect the vitamin-D-endocrinologic-system, diminishing the influence of VDR polymorphism on BMD and on bone turnover. We have examined the association of bone density, fracture predictivity and biochemical markers of bone turnover with VDR polymorphism in a German population. Blood and urine were collected from a heterogeneous subset of 164 caucasian subjects with ethnic German background. Polymerase chain reaction and subsequent digestion with Bsm I were used to examine variations of VDR genotypes. The morning following initial specimen collections, both urinary excretion rate of pyridinoline crosslinks (Pyr) and serum levels of bone alkaline phosphatase (BAP) were determined. For determination of the bone mineral density, the well-established method of dual X-ray absorptiometry was used. The VDR BB-genotype was associated with low bone mineral density for age-matched subjects (90.1 +/- 15.5%) versus the bb-genotype (100.8 +/- 10.8%) at the lumbar spine and at the Ward's triangle (91.8 +/- 17.9% versus 101.9 +/- 12.1%). 34.2% of BB-genotype subjects, 14.2% of bB-genotype subjects and 12.6% of bb-genotype subjects had Z-score related bone mineral density < 85%. The fracture rate at typical osteoporotic fracture sites was 23.6% for the BB-, 10.8% for the bB- and 0.0% for the bb-genotype. The urinary excretion rate of free pyridinoline crosslinks was higher for the BB-genotype than for the bB- or the bb-, however the difference was not significant. No genotype specific variations were seen for bone alkaline phosphatase. The authors conclude from this study that bone mineral density at the axial skeleton is associated with the vitamin-D-receptor allele polymorphism and that there is an influence on bone turnover and fracture rate in a German subset. The analysis of the VDR-genotype can be considered as a new piece in the puzzle of the diagnostic of osteoporosis for we get prognostic hints concerning the rate of fracture.

Vitamin K1 intake is associated with higher bone mineral density and reduced bone resorption in early postmenopausal Scottish women: no evidence of gene-nutrient interaction with apolipoprotein E polymorphisms

BackgroundPolymorphisms in the apolipoprotein E (APOE) gene are associated with fracture risk, and a potential mechanism is through vitamin K transport. ObjectiveWe investigated the relation between dietary vitamin K1 intake, APOE polymorphisms, and markers of bone health. DesignWe measured bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) in a cohort of Scottish women aged 49–54 y in 1990–1994 (baseline) and in 1997–2000 (visit 2). At visit 2, bone markers (urinary pyridinoline crosslinks and serum N-terminal propeptide of type 1 collagen) were measured, 3199 women completed a food-frequency questionnaire, and 2721 women were genotyped for APOE. ResultsCompared with quartile 3 (Q3) of energy-adjusted vitamin K1 intake (x̄: 116 μg/d), women in the lowest quartile (x̄: 59 μg/d) had lower BMD (analysis of variance; FN, Q1: 0.831 ± 0.122 g/cm2; Q3: 0.850 ± 0.126 g/cm2; P < 0.001; LS, Q1: 1.000 ± 0.170 g/cm2; Q3: 1.020 ± 0.172 g/cm2; P = 0.009), remaining significant at the FN after adjustment for age, weight, height, menopausal status or use of hormone replacement therapy, socioeconomic status, and physical activity (P = 0.04). Vitamin K1 intake was associated with reduced concentrations of pyridinoline crosslinks (Q1: 5.4 ± 2.0 nmol/mmol; Q4: 5.1 ± 1.9 nmol/mmol; P = 0.003). Carriers of the E2 allele had greater LS BMD at visit 2 and lost less BMD than did carriers of the E4 allele (E2: −0.50 ± 1.22%/y; E4: −0.71 ± 1.17%/y; P = 0.05). After adjustment for confounders, the P value for BMD loss (0.03 for LS and 0.04 for FN) did not reach the level of significance required for multiple testing (P = 0.012). No interaction was observed between dietary vitamin K and APOE on BMD. ConclusionsVitamin K1 intake was associated with markers of bone health, but no interaction was observed with APOE alleles on BMD or markers of bone turnover.

Estrogen receptor subtype-specific effects on markers of bone homeostasis

To further elucidate the processes involved in the physiology of bone-protection by estrogens, ovariectomized (OVX) rats were treated subcutaneously with 17beta-estradiol (E(2)), the ERalpha-specific agonist (16alpha-LE2) and the ERbeta-specific agonist (8beta-VE2). OVX and intact animals served as controls. Biomarkers of bone-formation (osteocalcin (OC), osteopontin (OPN)) and bone-resorption (telopeptides of collagen type I (CTx), pyridinoline cross-links (Pyd)) were quantified. Bone mineral density was measured by computed tomography. OVX-induced bone loss could be antagonized by subcutaneous administration of 17beta-estradiol and 16alpha-LE2. Serum levels of CTx, OC and OPN were significantly elevated in OVX compared to intact animals and reduced by 17beta-estradiol and 16alpha-LE2. Treatment of OVX rats with 8beta-VE2 did not affect bone mineral density (BMD) or bone-marker serum levels. Taken together, the complex expression pattern of bone-markers in OVX rats following subcutaneous administration of ER subtype-specific agonists indicates that 17beta-estradiol exerts its bone-protective effects by modulating the activity of osteoclasts and osteoblasts via ERalpha.