hydroxylysine and deoxypyridinoline

Analytical and biological variability of three bone markers, deoxypyridinoline (DPD), CrossLaps (CTx) and galactosylhydroxylysine (GHYL) were compared. From 14 healthy subjects (six women, eight men; age 29-44 years) recruited from our laboratory staff, two sets of samples of early morning urine were obtained - four samples taken weekly for 4 weeks (all subjects) and three samples taken monthly for 3 months from five subjects. Data were expressed as the ratio to creatinine concentration. All the methods met the analytical goals (CV(A)< or =1/2CV(I(within-subject))) DPD 0.06, CTx 0.05 and GHYL 0.07 with CV(I(within-subject)) being 0.22, 0.19 and 0.38, respectively. The reference values were of limited usefulness particularly for CTx and GHYL, the index of individuality (II) being 0.50 and 0.48 respectively. As the index of heterogeneity (IH) was not significant, being 0.23 for CTx, 0.28 for DPD and 0.46 for GHYL, which are all <1.71 (1+2S.D.), within-subject variances can be used to calculate the reference change value (RCV): 0.58 for DPD, 0.54 for CTx and 1. 08 for GHYL. Moreover, we found constant variations in DPD and CTx, week to week and month to month. Our findings suggest that DPD and CTx provide more reliable results than GHYL, showing a lower within-subject variation, a lower and time-constant RCV allowing reliable monitoring without regard for timing.

Topics: Adult; Algorithms; Amino Acids; Biomarkers; Bone and Bones; Collagen; Collagen Type I; Female; Humans; Hydroxylysine; Immunoassay; Male; Peptides

The study intends to investigate the relationship of body composition (%fat, percent body fat; FM, fat mass; FFM, fat free mass; FA and MA cross-sectional fat and muscle area) to the urinary excretion of deoxypyridinoline (DPD) and galactosyl-hydroxylysine (Gal-Hyl). 231 healthy children and adolescents (age 5-19 years; 112 males) of the DONALD study were analyzed for FM and FFM by measuring 4 skinfold thicknesses, for DPD and Gal-Hyl in urine samples and for bone parameters, FA and MA at the forearm by peripheral quantitative computed tomography. In contrast to adrenarchal females, adrenarchal males with low %fat had low levels of DPD and Gal-Hyl. %fat was correlated with DPD in pre-adrenarchal males (r = 0.290) and females (r = 0.298). Cortical bone mineral density (BMDcort) was correlated with DPD (r = -0.351) in adrenarchal males. Controlled for BMDcort, FM was correlated with DPD in pre-adrenarchal males (r = 0.348), and FA was correlated with DPD in pre-adrenarchal females (r = 0.294). FFM was negatively correlated with Gal-Hyl in adrenarchal males (r = -0.436) and females (r = -0.338). Less than 40% of variance of excreted DPD and Gal-Hyl was explained by regression models based on parameters of body composition. The effect of body composition explains the minor part of variance of the urinary excretion of DPD and Gal-Hyl. The association of body composition to excreted DPD and Gal-Hyl was not explained by the effect of adipose tissue on bone formation and bone resorption.

Topics: Adipose Tissue; Adolescent; Adult; Amino Acids; Anthropometry; Body Composition; Bone Density; Bone Resorption; Child; Female; Humans; Hydroxylysine; Male; Regression Analysis

The paper reports some successful results on the first fully stereoselective total synthesis of the collagen cross-link pyridinolines. All stereogenic centers are stereoselectively introduced using Williams glycine template methodology, and oxazinones are used as a source of chirality and as easily removable protecting groups of the amino acidic functionalities during the assembly of the pyridinoline nucleus.

Topics: Amino Acids; Biomarkers; Chemistry, Organic; Collagen; Humans; Hydroxylysine; Magnetic Resonance Spectroscopy; Molecular Structure

In children and adolescents, markers of bone and collagen metabolism reflect the dynamics of skeletal growth and development. The aim of this study was to assess the relationship of the urinary collagen markers deoxypyridinoline (DPD) and hydroxylysine (Hyl) and its glycosides [galactosyl-Hyl (Gal-Hyl) and glucosyl-Gal-Hyl] with growth.. Urine samples from 240 apparently healthy children and adolescents (6-19 years; 124 girls) and from 51 prepubertal children with growth hormone (GH) deficiency (3-14 years; 14 girls) were analyzed. Urinary Hyl and its glycosides were quantified by HPLC, and DPD was assessed by chemiluminescence assay. Urinary concentrations of all markers were related to urinary creatinine.. Multiple regression analysis revealed that only age and height velocity were independently associated with these markers in healthy children. In GH-deficient patients, the urinary excretion of both analytes after 4 weeks of GH therapy correlated significantly with the height increase during the first treatment year (r = 0.79 for Gal-Hyl; r = 0.70 for DPD; P <0.001 each). In a multivariate linear regression model using Gal-Hyl concentrations at 4 weeks, baseline concentrations of insulin-like growth factor 1 and height velocity after 3 months accounted for 80% of the variability in height gain during the first treatment year. A model using DPD concentrations at 4 weeks, in place of Gal-Hyl concentrations, as well as baseline concentrations of insulin-like growth factor 1 and height velocity after 3 months accounted for 83% of the variability.. These urinary bone and collagen markers give some early indication of growth response, but the prediction of an individual marker is too imprecise to serve as a basis for clinical decisions. Markers of bone and collagen metabolism might be more useful as components of multivariate growth prediction models.

Topics: Adolescent; Adult; Amino Acids; Biomarkers; Child; Child, Preschool; Chromatography, High Pressure Liquid; Collagen; Dwarfism, Pituitary; Glycosides; Growth; Humans; Hydroxylysine; Luminescent Measurements; Prospective Studies; Reference Values; Regression Analysis

The brittleness of bone in patients with osteogenesis imperfecta (OI) has been attributed to an aberrant collagen network. However, the role of collagen in the loss of tissue integrity has not been well established. To gain an insight into the biochemistry and structure of the collagen network, the cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) and the level of triple helical hydroxylysine (Hyl) were determined in bone of OI patients (types I, III, and IV) as well as controls. The amount of triple helical Hyl was increased in all patients. LP levels in OI were not significantly different; in contrast, the amount of HP (and as a consequence the HP/LP ratio and the total pyridinoline level) was significantly increased. There was no relationship between the sum of pyridinolines and the amount of triple helical Hyl, indicating that lysyl hydroxylation of the triple helix and the telopeptides are under separate control. Cross-linking is the result of a specific three-dimensional arrangement of collagens within the fibril; only molecules that are correctly aligned are able to form cross-links. Inasmuch as the total amount of pyridinoline cross-links in OI bone is similar to control bone, the packing geometry of intrafibrillar collagen molecules is not disturbed in OI. Consequently, the brittleness of bone is not caused by a disorganized intrafibrillar collagen packing and/or loss of cross-links. This is an unexpected finding, because mutant collagen molecules with a random distribution within the fibril are expected to result in disruptions of the alignment of neighboring collagen molecules. Pepsin digestion of OI bone revealed that collagen located at the surface of the fibril had lower cross-link levels compared with collagen located at the inside of the fibril, indicating that mutant molecules are not distributed randomly within the fibril but are located preferentially at the surface of the fibril.

Topics: Adolescent; Adult; Amino Acids; Arginine; Biomarkers; Biopsy; Bone and Bones; Child; Child, Preschool; Collagen; Humans; Hydroxylysine; Infant; Lysine; Osteogenesis Imperfecta; Pepsin A; Pyridinium Compounds; Reference Values

To investigate age related and site specific variations in turnover and chemistry of the collagen network in healthy tendons as well as the role of collagen remodelling in the degeneration of the supraspinatus tendon (ST-D) in rotator cuff tendinitis.. Collagen content and the amount of hydroxylysine (Hyl), hydroxy-lysylpyridinoline (HP), lysylpyridinoline (LP), and the degree of non-enzymatic glycation (pentosidine) were investigated in ST-D and in normal human supraspinatus (ST-N) and biceps brachii tendons (BT-N) by high-performance liquid chromatography.. In BT-N, tendons that served as control tissue as it shows rarely matrix abnormalities, pentosidine levels rise linearly with age (20-90 years), indicating little tissue remodelling (resulting in an undisturbed accumulation of pentosidine). A similar accumulation was observed in ST-N up to 50 years. At older ages, little pentosidine accumulation was observed and pentosidine levels showed large interindividual variability. This was interpreted as remodelling of collagen in normal ST after age 50 years because of microruptures (thus diluting old collagen with newly synthesised collagen). All degenerate ST samples showed decreased pentosidine levels compared with age matched controls, indicating extensive remodelling in an attempt to repair the tendon defect. Collagen content and the amount of Hyl, HP, and LP of ST-N and BT-N did not change with age. With the exception of collagen content, which did not differ, all parameters were significantly (p < 0.001) lower in BT-N. The ST-D samples had a reduced collagen content and had higher Hyl, HP, and LP levels than ST-N (p < 0.001).. Inasmuch as Hyl, HP, and LP levels in ST-N did not change with age, tissue remodelling as a consequence of microruptures does not seem to affect the quality of the tendon collagen. On the other hand, the clearly different profile of post-translational modifications in ST-D indicates that the newly deposited collagen network in degenerated tendons is qualitatively different. It is concluded that in ST-D the previously functional and carefully constructed matrix is replaced by aberrant collagen. This may result in a mechanically less stable tendon; as the supraspinatus is constantly subjected to considerable forces this could explain why tendinitis is mostly of a chronic nature.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aging; Amino Acids; Arginine; Child; Chronic Disease; Collagen; Cross-Linking Reagents; Humans; Hydroxylation; Hydroxylysine; Lysine; Middle Aged; Rotator Cuff; Tendinopathy

Diurnal variations in the excretion of bone resorption markers were assessed in order to identify the type of urine collection which provides the most information on bone resorption rate and its relation to measuring bone dynamics in a postmenopausal population. Sixty women, ages 43-67 and without disease or treatment known to affect bone mineral density, were divided into two groups on the basis of femoral mineral density T-score: <1.5 (Group I), >1.5 (Group II). Bone formation was assessed by measuring bone alkaline phosphatase activity and osteocalcin concentration, bone resorption by urinary hydroxyproline, pyridinoline and deoxypiridinoline, N-telopeptide, galactosyl hydroxylysine, and CrossLaps. To identify the more appropriate collection times, urine samples were collected from 7 am to 3 pm; from 3 pm to 11 pm; from 11 pm to 7 am. Twenty-four hour urine collection and first morning void urine samples were also measured. The findings suggest that nocturnal collection and first morning void samples provide the most reliable data on the rate of bone degradation, possibly showing bone loss not only in osteopenic patients but also in women with a low T-score. Nocturnal and first morning samples should therefore be recommended in order to standardize sample collection, as they enable an accurate assessment of bone resorption markers and improved comparability to results from different studies, as well as a less cumbersome collection modality.

Topics: Adult; Aged; Alkaline Phosphatase; Amino Acids; Biomarkers; Bone Density; Bone Resorption; Collagen; Collagen Type I; Female; Humans; Hydroxylysine; Hydroxyproline; Middle Aged; Osteocalcin; Peptide Fragments; Peptides

Keloid is a tissue with an excessive accumulation of collagen. In this study, we have partially characterized post-translational modifications of type I collagen in human keloid in order to pursue their potential involvement in this pathology. The levels of lysyl hydroxylation of the helical portions of alpha 1 and alpha 2 chains of type I collagen in keloid were significantly higher than those of normal, while the levels of prolyl hydroxylation were identical between these two groups. The contents of the major reducible cross-links in dermal collagen, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymero-desmosine, were both significantly higher in keloids (up to sixfold) than those of normal. In addition, significant amounts of hydroxylysine-aldehyde derived cross-links that are characteristic of skeletal tissue collagens, dehydro-dihydroxylysinonorleucine (about 0.3 mole/mole of collagen) and pyridinoline (about 0.1 mole/mole of collagen), were found in keloids. These results indicate that keloid-forming cells are phenotypically different from those in normal dermis and that the collagen produced is highly cross-linked. The increased cross-linking provides the fibrils with more stability that may result in an accumulation of collagen.

Topics: Adult; Amino Acids; Collagen; Cross-Linking Reagents; Desmosine; Dipeptides; Histidine; Humans; Hydroxylation; Hydroxylysine; Hydroxyproline; Keloid; Middle Aged; Protein Processing, Post-Translational; Protein Structure, Secondary; Skin

Galactosylhydroxylysine (GHL) is released during bone resorption and has been shown to be elevated in subjects with metabolic bone loss. GHL is relatively specific for bone, it is not recycled or significantly metabolized during collagen turnover, and the levels are not influenced by diet. Previous measurements of GHL levels in urine have been performed using reverse-phase high performance liquid chromatography following pre-column derivatization. We produced polyclonal antibodies to GHL using GHL purified from sea sponges and developed an immunoassay that can recognize GHL in urine. The antibodies have minimal cross-reactivity with a physiological mixture of amino acids (< 1%), galactose (< 0.2%), lactose (< 0.3%), and glucosylgalactosylhydroxylysine (< 1%). This competitive immunoassay requires no dilution or pretreatment of the samples and provides a rapid and easy method for the evaluation of GHL in urine. Analysis of clinical samples from normal individuals, post-menopausal women, osteoporotic patients and individuals with Paget's disease show that the assay can discriminate between groups with differing levels of bone resorption as well as deoxypyridinoline (Dpd).

Topics: Adult; Aged; Amino Acids; Animals; Biomarkers; Bone Resorption; Chromatography, High Pressure Liquid; Collagen; Female; Humans; Hydroxylysine; Immunoassay; Male; Middle Aged; Osteitis Deformans; Osteoporosis; Osteoporosis, Postmenopausal; Porifera; Postmenopause; Rabbits; Reference Values; Reproducibility of Results; Sensitivity and Specificity

Ehlers-Danlos syndrome type VI (EDS VI) is an autosomal recessive disorder of connective tissue characterized by hyperextensible, friable skin and joint hypermobility. Severe scoliosis and ocular fragility are present in some patients. This disease is caused by defective collagen lsyl hydroxylase, a vitamin C-dependent enzyme that converts lysyl residues to hydroxylysine on procollagen peptides. Hydroxylysine is essential for the formation of the covalent pyridinium cross-links pyridinoline (Pyr) and deoxypyridinoline (Dpyr), among mature collagen molecules. Pyr derives from three hydroxylysyl residues, whereas Dpyr derives from one lysyl and two hydroxylysyl residues. Patients with EDS VI have high urinary excretion of Dpyr, resulting in a high ratio of Dpyr-Pyr. In this study, we evaluate content and production of pyridinium cross-links in the skin and cultured fibroblasts from patients with EDS VI. The skin of normal controls contained both Pyr and Dpyr, with a marked predominance of Pyr as observed in normal urine. The skin of patients with EDS VI had reduced total content of pyridinium cross-links, with the presence of Dpyr but not Pyr. Long-term cultures of control fibroblasts produced both Pyr and Dpyr, with a pattern resembling that of normal skin. By contrast, cross-links were not detected in dermal fibroblasts cultured from patients with EDS VI. Vitamin C, which improves the clinical manifestations of some patients with EDS VI, decreased Dpyr accumulation though only minimally affecting Pyr content in control cells. By contrast, addition of vitamin C to fibroblasts from patients with EDS VI stimulated the formation of Dpyr more than that of Pyr and greatly increased total pyridinium cross-link formation. These results indicate that qualitative and quantitative alterations of pyridinium cross-links occur in skin and in cultured dermal fibroblasts of patients with EDS VI and may be responsible for their abnormal skin findings. The vitamin C-stimulated production of Dpyr and Pyr in fibroblasts from patients with EDS VI may explain at least in part the therapeutic effects of this vitamin in EDS VI.

Topics: Adolescent; Amino Acids; Ascorbic Acid; Cells, Cultured; Child; Collagen; Cross-Linking Reagents; Ehlers-Danlos Syndrome; Female; Fibroblasts; Humans; Hydroxylysine; Lysine; Pyridinium Compounds; Skin

The bone mineral density and the biochemical parameters exploring bone cell activities were analyzed in two cosmonauts who spent 1 and 6 months, respectively, in the Russian MIR station. Measurements were performed before the flight, after the flight, and after a recovery period. At the end of the first month, peripheral QCT measurements indicated a slight decrease of trabecular bone mass in the distal tibial metaphysis. However, after 6 months of spaceflight, a more marked loss of trabecular and cortical bones was observed in the tibia, and was still significant after 6 month recovery in the trabecular compartment, whereas a decrease was no longer observed in the cortical envelope. No change was observed in either compartment of the distal radius at any time. Ultrasound BUA of the calcaneus was greatly reduced by the first month, followed by a more dramatic decrease after month 6. Ultrasound SOS detected no change. Parameters reflecting bone formation activity appeared to be depressed after both missions. In contrast, no dramatic change in resorption parameters was observed, except for a trend toward an increase in pyridinoline. In conclusion, the lower weight-bearing bones appeared more sensitive than the upper ones in terms of spaceflight-induced bone loss. This probably explained the absence of marked systemic biochemical data changes. This study further suggests that recovery in the tibial trabecular compartment 6 months after landing was not completed after a 6 month mission.

Topics: Adult; Alkaline Phosphatase; Amino Acids; Astronauts; Biomarkers; Bone and Bones; Bone Density; Bone Development; Bone Resorption; Humans; Hydroxylysine; Male; Osteocalcin; Peptide Fragments; Procollagen; Space Flight; Tomography, X-Ray Computed; Ultrasonography; Weightlessness

The aim of this study was to compare urinary galactosylhydroxylysine (GHyl) and deoxypyridinoline (d-Pyr) as biochemical markers of bone resorption in post-menopausal women treated and untreated with estrogen and cyclic etidronate. Fasting urinary GHyl, D-Pyr, pyridinoline, serum osteocalcin and total alkaline phosphatase were measured in three subgroups, i.e. post-menopausal women undergoing hormone replacement therapy, untreated post-menopausal women and post-menopausal women with low BMD treated with disodium etidronate. The results indicated that GHyl did not significantly discriminate between untreated post-menopausal women and estrogen replated ones unless an osteoporotic untreated group was selected. d-Pyr and GHyl showed similar performances when their values after bisphosphonate treatment were compared to those found in untreated post-menopausal women, thus suggesting that both markers were equal in their ability to detect the bone response to cyclic etidronate administration. This observation further proves the statement that GHyl is prone to confounding factors under estrogen therapy but it is adequate as is d-Pyr in monitoring the bone response to bisphosphonate treatment.

Topics: Aged; Amino Acids; Biomarkers; Bone Resorption; Collagen; Estrogen Replacement Therapy; Etidronic Acid; Female; Humans; Hydroxylysine; Middle Aged; Postmenopause

Hypertrophic cartilage from the tibiotarsus of Day 20 chick embryonic tibiae was found to contain an unusually high concentration of lysylpyridinoline (LP), a nonreducible collagen cross-link normally found only in bone and dentin but not in cartilage. Since type X collagen is abundant in this cartilage, research was conducted to see if type X was the primary source of LP. The 45-kDa pepsin-resistant form of type X was purified by immunoaffinity chromatography. It contained a high concentration of the LP cross-link while type II contained primarily hydroxylysylpyridinoline (HP), the predominant cross-link in cartilage. This, to our knowledge is the first time that type X has been shown directly to form nonreducible cross-links and that a collagen other than type I has a high level of LP. Also, it is interesting that the HP and LP cross-links are found in a collagen that is degraded so rapidly. Possible explanations for these findings are discussed.

Topics: Amino Acids; Animals; Cartilage; Chick Embryo; Collagen; Cross-Linking Reagents; Electrophoresis, Polyacrylamide Gel; Hydroxylysine; Hypertrophy; Molecular Weight; Pepsin A; Tibia

We have previously shown that galactosyl hydroxylysine (GHYL), pyridinoline (PYD), and deoxypyridinoline (DPD) have a better accuracy and discriminate power than hydroxyproline in distinguishing postmenopausal osteoporotic women from premenopausal controls. In this study, we evaluated the clinical performances of GHYL, PYD, and DPD, alone or in combination, in distinguishing postmenopausal osteoporotic women (OPBD, n = 26) from age-matched controls (CBD, n = 19). The diagnosis of osteoporosis was based upon the bone density (BD) of the lumbar spine measured by quantitative computed tomography (CBD: BD > 108 mg/cm3; OPBD: BD < 70 mg/cm3). Urinary excretion of GHYL, PYD, and DPD were measured by HPLC, and all data were expressed as the molar ratio with the creatinine excretion (GHYL/CR, PYD/CR, and DPD/CR). The clinical performances were tested by: Z score analysis (Z), Receiver Operated Characteristic curve analysis (%Acc) and logistic-regression analysis of the posterior probabilities for prediction from a logistic model (LOGIST). GHYL/CR, PYD/CR, and DPD/CR were significantly increased in OPBD compared with CBD. The clinical performances were similar for the three assays, with slightly better performances for GHYL/CR (GHYL/CR: Z = 3.14, %Acc = 70 +/- 8, LOGIST P = 0.01; PYD/CR: Z = 2.19, %Acc = 67 +/- 8, LOGIST P = 0.051; DPD/CR: Z = 2.13, %Acc = 65 +/- 8, LOGIST P = 0.06). None of the possible combinations of the three assays yielded better clinical performances than GHYL/CR alone. In conclusion, this study further confirms the validity of GHYL, PYD, and DPD as markers of bone resorption.

Topics: Aged; Amino Acids; Bone Density; Creatinine; Female; Humans; Hydroxylysine; Middle Aged; Osteoporosis, Postmenopausal; Regression Analysis; Sensitivity and Specificity

Glucosylgalactosylhydroxylysine (GGHYL), galactosylhydroxylysine (GHYL), pyridinoline (PYD) and deoxypyridinoline (DPD) were measured in the urine (6 h serial specimens over 96 and 24 h urine specimens for 4 days) collected from four adult Sprague Dawley rats and in the femoral and tibia] bone as well as in the dorsal skin of the same rats. No significant daily variations were found in the urine excretion of GGHYL, GHYL, PYD and DPD but significant diurnal variations. The GGHYL/GHYL ratio in rat urine (0.46 +/- 0.1) reflected neither the bone collagen ratio (1.9 to 2.4) nor the skin collagen ratio (1.22 +/- 1.07), a finding that may reflect GGHYL conversion into GHYL. The content of both pyridinolines was very low in the skin and high in the bone collagen and the urinary PYD/DPD ratio (1.46 +/- 0.15) reflected essentially the bone collagen ratio (0.8-3.0). These results suggest the usefulness of measuring GGHYL, GHYL, PYD and DPD in 24 h urine specimen and, based on the inter-animal variations, the necessity to consider each animal as its own control when bone turnover needs to be monitored.

Topics: Amino Acids; Animals; Biomarkers; Bone and Bones; Collagen; Cross-Linking Reagents; Glycosides; Humans; Hydroxylysine; Male; Pyridinium Compounds; Rats; Rats, Sprague-Dawley; Skin; Time Factors

We studied the molecular packing of collagen fibrils by x-ray diffraction in skin specimens of patients with lipodermatosclerosis and in controls. A difference in the tilt angles of the collagen molecules relative to the fiber axis is suggested by a D-stagger that is 1 nm larger in sclerotic skin than in normal skin. In parallel, the collagen cross-links in the skin specimens were analyzed, and a marked increase of both hydroxylysylpyridinoline and lysylpyridinoline, the trivalent mature cross-links characteristic of skeletal tissues, was found. The content of hydroxylysylpyridinoline and lysylpyridinoline was higher in the deep layer of the affected dermis than in the superficial dermis. This increase was always accompanied by an increase in the hydroxylysylpyridinoline/lysylpyridinoline ratio, suggesting that hydroxylysylpyridinoline is a sclerosis-associated cross-link. In addition, lysyl hydroxylation was increased in affected skin, and this increase was apparently restricted to the collagen telopeptides, which are crucial anchoring structures for lysyl dependent cross-links.

Topics: Amino Acids; Biopsy; Collagen; Drug Residues; Humans; Hydroxylysine; Hydroxyproline; Leg; Reference Values; Scleroderma, Localized; Skin; X-Ray Diffraction

This study was undertaken to assess the sensitivity of hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) to monitor bone response to estrogen deficiency and replacement by comparing their excretory patterns in ovariectomized aged (11-14 months old) rats. The ovariectomized (OVX) rats were randomized into two groups: (1) OVX plus vehicle; (2) OVX plus 17 beta-estradiol (17-beta E, 10 micrograms/kg, s.c., 4 days/week). Treatment with 17-beta E started immediately after OVX and continued for 60 days. The collagen catabolites were measured in urine for 1 month before OVX and thereafter for 60 days. In temporal coincidence with urine collection, bone area and bone mineral density (BMD) of lumbar vertebrae, femoral diaphysis and distal metaphysis were measured by dual-energy X-ray absorptiometry. In the untreated rats, BMD of the femoral metaphysis and lumbar vertebrae decreased significantly and the urinary excretion of LP, HP, GHyl and GGHyl increased with different patterns. In the treated rats, 17-beta E replacement prevented the increment in LP excretion, partially prevented the increase in HP excretion, but had no effect on the excretion of GHyl and GGHyl. In conclusion pyridinolines and glycosides have different sensitivities to the bone response to OVX. Glycoside excretion after OVX also reflects metabolic processes not strictly related to bone loss and, in contrast with LP, is not sensitive to estrogen replacement.

Topics: Absorptiometry, Photon; Amino Acids; Animals; Biomarkers; Bone and Bones; Estradiol; Estrogen Replacement Therapy; Female; Hydroxylysine; Ovariectomy; Pyridinium Compounds; Random Allocation; Rats; Rats, Sprague-Dawley

Galactosyl-hydroxylysine (Gal-Hyl) is the predominant product of the posttranslational glycosylation of skeletal collagen. Urinary Gal-Hyl excretion is regarded as a marker of bone resorption in adults, but little information is available on the validity of this parameter in pediatric age groups. Using 24-h urine samples from 88 healthy children and adolescents ages 4-18 yr, reference ranges were established for this age group, and values were compared with measurements in children with overt GH deficiency (n = 14) or Ullrich-Turner syndrome (n = 21). When expressed relative to body weight (Gal-Hyl/wt), urinary Gal-Hyl excretion was 3.2 to 4.7 times higher in subjects 4-16 yr of age than in adults. Highest values were observed in very young children and during the pubertal growth spurt. In the total population, urinary Gal-Hyl/wt was closely related to growth velocity (r = 0.72) and significantly correlated with the urinary excretion of both hydroxyproline (r = 0.74) and deoxypyridinoline (r = 0.88; P < 0.001 each). Urinary Gal-Hyl/wt was significantly lower in children with GH deficiency or Ullrich-Turner syndrome than in healthy children (P < 0.001 each). The urinary excretion of Gal-Hyl was significantly correlated with growth velocity in GH-deficient children (r = 0.69; P = 0.004) but not in patients with Ullrich-Turner syndrome. In the latter, the increase in urinary Gal-Hyl excretion after 3 months of treatment with recombinant human GH correlated significantly with the increase in growth velocity after 12 months of treatment (r = 0.76; P = 0.002). We conclude that the urinary excretion of Gal-Hyl is a valid and potentially useful index of skeletal growth in children.

Topics: Adolescent; Adult; Aging; Amino Acids; Biomarkers; Bone Resorption; Child; Child Development; Child, Preschool; Female; Growth Disorders; Growth Hormone; Humans; Hydroxylysine; Hydroxyproline; Male; Recombinant Proteins; Reference Values

This study evaluated whether pyridinium cross-links, which are positively charged, besides renal clearance are also cleared by the liver into bile. In 13 human bile samples tested, we were able to detect both pyridinoline (PYD) and deoxypyridinoline (DPD) in small amounts which were estimated to be about 1-2% of the amount usually found in urine. To further evaluate the amount of pyridinium cross-links excreted through bile, we studied the stability of these compounds at the alkaline pH of bile. No effect on their stability was detected over a 6-hour incubation. The origin of these molecules in bile and the significance of this finding in the use of PYD and DPD as bone resorption markers are discussed.

Topics: Adult; Aged; Amino Acids; Bile; Cross-Linking Reagents; Female; Humans; Hydroxylysine; Male; Middle Aged; Pyridinium Compounds

Galactosyl hydroxylysine and deoxypyridinoline are at present the most promising markers of bone resorption. Various studies have indeed shown that these two markers discriminate with high accuracy subjects with different rates of bone turnover and that their accuracies and discriminate power are very similar. The aim of this paper is to compare the practicality and the reproducibility of the HPLC galactosyl hydroxylysine and deoxypyridinoline assays. In summary, this review shows that the galactosyl hydroxylysine and deoxypyridinoline HPLC assays differ mainly in the need, in using deoxypyridinoline, for an acid hydrolysis and a preextraction of the urine samples. This implies two major problems for deoxypyridinoline: 1) more time is required due to the cumbersome preanalytical procedures; and 2) a lower reproducibility. Our data, in fact, show that both the intra-assay and inter-assay coefficient of variation of the deoxypyridinoline assay are almost 100% higher than those of the galactosyl hydroxylysine assay.

Topics: Adult; Amino Acids; Biomarkers; Bone Resorption; Child; Chromatography, High Pressure Liquid; Female; Humans; Hydroxylysine; Molecular Weight; Reproducibility of Results

We compared the clinical performances of four bone-resorption (BR) assays (hydroxyproline, HYP; galactosyl hydroxylysine, GHYL; deoxypyridinoline, DPD; and pyridinoline, PYD) in subjects with different BR rates: normal (adult men and premenopausal women), mildly increased (postmenopausal osteoporotic women), high (Paget disease patients), and very high (children). The discrimination power (Z score) and the accuracy (estimated by receiver-operating characteristic analysis) for GHYL, DPD, and PYD were compared with those for HYP. Discrimination power and accuracy were similar for high- and very-high-BR groups for all four assays. However in the mildly increased-BR group, DPD, GHYL, and PYD showed a higher discrimination power and accuracy than did HYP. The clinical performances of HYP, DPD, GHYL, and PYD are comparable for large changes in BR. For modest changes, DPD, GHYL, and PYD are more accurate and have a higher discrimination power than does HYP.

Topics: Adult; Aged; Amino Acids; Biomarkers; Bone Resorption; Child; Chromatography, High Pressure Liquid; Female; Humans; Hydroxylysine; Hydroxyproline; Male; Middle Aged; Osteitis Deformans; Osteoporosis, Postmenopausal; Pyridinium Compounds

The pyridinium derivatives hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) are intermolecular crosslinking compounds of collagen which are only present in its mature form. Contrasting to the wide distribution of type I and II collagens, HP and LP are absent from skin, ligament and fascia, and their major sources are bone and cartilage. Using a specific HPLC assay, we have determined the 24-h excretion of HP and LP crosslinks in normal adults of both sexes, in patients with primary hyperparathyroidism and in patients with Paget's disease of bone before and after intravenous treatment with amino-propylidene bisphosphonate (APB). Mean adult normal values were 33 +/- 13 pmol/mumol creatinine for HP and 6.3 +/- 3.4 pmol/mumol creatinine for LP. In women, menopause induced a 2-3-fold increase of HP and LP reflecting the well documented postmenopausal increase of bone turnover. In the urine of patients with primary hyperparathyroidism and of patients with active Paget's disease of bone, urinary crosslinks were significantly higher than in age-matched controls, with a mean 3- and 12-fold increase, respectively. Urinary excretion of hydroxyproline is a well recognized but poorly sensitive marker of bone turnover, reflecting resorption. In the same patients, the effect of menopause and disease state on hydroxyproline excretion was much less dramatic than on HP and LP. During intravenous APB treatment of pagetic patients, there was an early decrease of HP and LP, which was significant after 24 h and reached 62% at 4 days, contrasting with a late and milder decrease of urinary hydroxyproline. Because APB is a potent inhibitor of resorption which does not have a direct short-term effect on bone formation, these data also indicate that urinary excretion of HP and LP reflect only collagen degradation occurring during osteoclastic resorption and not the degradation of newly synthesized collagen. We conclude that urinary HP and LP excretion represents the first sensitive and specific marker of bone resorption. Its use should be valuable in the clinical investigation of metabolic bone diseases, especially osteoporosis.

Topics: Adult; Aged; Alkaline Phosphatase; Amino Acids; Bone Diseases, Metabolic; Bone Resorption; Chromatography, High Pressure Liquid; Female; Humans; Hydroxylysine; Hyperparathyroidism; Lysine; Male; Menopause; Middle Aged; Osteitis Deformans; Pyridinium Compounds; Reference Standards

Two intermolecular cross-linking amino acids, hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP), are promising markers in urine of collagen resorption because their levels in urine should reflect only collagen resorption and, unlike hydroxyproline, should not be influenced by degradation of either newly synthesized collagen molecules or noncollagenous proteins. Changes with age in the urinary excretion of HP and LP were studied in 24 h collections of urine from a group of 22 male and 27 female healthy subjects aged from 2 to 70 years. The pyridinolines were quantitated, utilizing their natural fluorescence, after resolution by reversed-phase HPLC. Levels of both pyridinolines were higher in children than in adults, but in adults no evidence of age or sex variations were observed except in the 20-30 year age group. Mean values of HP/Cr and LP/Cr in 37 adults (21-70 years) were 27.2 +/- 1.9 and 8.8 +/- 0.8 mumols/mol, respectively; in the 12 children (2-15 years) the mean values were 14.4 and 12.4 times higher than the respective adult values. Making certain assumptions, the mean amount of bone resorbed in normal adults was tentatively estimated at 1.9 g per 24 h. The finding that differences between children and adults in these relatively specific markers were greater than with hydroxyproline suggests that hydroxyproline values may considerably underestimate the actual amount of bone turnover occurring in growing children or overestimate the adult turnover rate.

Topics: Adult; Aged; Aging; Amino Acids; Biomarkers; Bone and Bones; Bone Resorption; Chromatography, High Pressure Liquid; Collagen; Female; Humans; Hydrolysis; Hydroxylysine; Lysine; Male; Middle Aged; Pyridinium Compounds; Reference Standards; Reference Values

A recent report claimed that an amine in human skin (believed to be pyridinoline) was deficient in specimens from patients with abdominal aortic aneurysms (AAA). Further studies suggest that this work was erroneous in two respects. First, the amine has been isolated and partially characterized; the major component of the peak of interest is a deoxyanalogue of pyridinoline. It may be a collagen cross-link of some biologic importance, because it is not detectable in skin from a patient with Marfan's syndrome. Second, further studies in an additional 19 patients with AAA and an additional 13 controls suggest that this amine is abnormally abundant in skin from patients with AAA. This difference cannot be accounted for by any potential source of artifact that has been traceable. The effects of age, diabetes, sex, race, site of biopsy, and source of specimen (autopsy versus surgery) have been studied; none of these variables can account for the high ratio of pyridinolines to hydroxylysine found in skin from patients with AAA.

Topics: Adolescent; Adult; Aged; Amino Acids; Aorta, Abdominal; Aortic Aneurysm; Chromatography, High Pressure Liquid; Diabetes Mellitus; Female; Humans; Hydroxylysine; Male; Middle Aged; Skin