Urinary Cross-linked N-terminal Telopeptide of Type I Collagen Levels of Infants with Osteogenesis Imperfecta and Healthy Infants.

The urinary cross-linked N-terminal telopeptide of type I collagen (uNTx) levels in infantile osteogenesis imperfecta (OI) have not been well studied. Here we investigated the levels of uNTx in infants with OI and healthy infants. We collected spot urine samples from 30 infants with OI (male/female, 14/16; Sillence classification, I/II/III/IV: 15/3/6/6; age, 5.2±4.4 months) and 120 healthy infants (male/female, 75/45; age, 5.1±4.1 months) for the measurement of uNTx levels. The uNTx levels of the OI infants were significantly lower than those of the healthy infants (mean±SD, 1,363.7±530.1 vs. 2,622.2±1,202.6 nmol BCE/mmol Cr; p＜0.001). The uNTx levels of the infants with type I OI were significantly lower than those of the age-matched healthy infants, although an overlap was observed between the 2 groups. Among the 1-month-old infants, the uNTx levels of the infants with types I, III or IV OI were significantly lower than those of the healthy infants, without overlap (1,622.5±235.8 vs. 3,781.0±1,027.1 nmol BCE/mmol Cr; p＜0.001). These results indicate that uNTx levels are significantly lower in infants with OI than in healthy infants, and they suggest that uNTx might be useful as a reference for diagnosing OI.

[Brittle bone disease type III in neonates--own experience]. / Wrodzona lamliwosc kosci typu III u noworodków--obserwacje wlasne.

UNLABELLED: Fractures of long bone and ribs in the neonatal period may be expression of genetic disturbances of collagen type I production. The aim of the study was to present clinical symptoms, results of radiological, biochemical and densitometric examinations in 11 newborns with osteogenesis imperfecta type III. METHODS: In all children accurate medical history, clinical examination and radiograph were performed. We measured concentration of 25-hydroxyvitamin D (25OHD) and osteocalcin (bone formation marker) in serum. Urinary excretion of bone resorption marker type I collagen N-telopeptide related to creatinine were made. In 5/11 children densitometric examination in Infant programme by DXA method (dual-X-ray absorptiometry) were done. RESULTS: In all family osteogenesis imperfecta occurred by the first. In clinical examination deformities in body proportion, shortness of the extremities, sabre shanks, flabbily of skull bones and reduction of activity were diagnosed. 8/11 newborns had blue sclera. In all X-ray (baby-gram) bone fractures occurring in utero as well as after birth were founded. In biochemical indices a small numbers of abnormality were described. In 5/11 newborns with results of densitometric examination normal bone mineral density adequate to body mass were demonstrated, in 3/5 bone mineral content (BMC) were decreased. CONCLUSION: 1.Osteogens esis imperfecta is the one of reasons of bone fractures in neonates and its diagnosis is based on family history, clinical manifestation and X-ray examination. 2. In newborns with bone fractures dual X-ray absorptiometry are recomendated.

Pamidronate treatment of children with moderate-to-severe osteogenesis imperfecta: a note of caution.

BACKGROUND/AIMS: Bisphosphonates have been reported to decrease fractures related to osteogenesis imperfecta (OI). We assessed the efficacy and long-term safety of pamidronate therapy in patients with moderate-to-severe OI. METHODS: We conducted an open-label uncontrolled study in 14 boys and 13 girls whose mean age was 6.8 years at baseline. Intravenous pamidronate, 1 mg/kg/day, was given for 3 consecutive days every 4 months for 2-6 years, with physical therapy and orthopedic surgery as appropriate. Mobility score, fracture rate, height, bone mineral density (BMD) and bone healing were evaluated throughout follow-up. RESULTS: In 24 (89%) patients, the fracture rate decreased to 6 months) occurred in 8 (29.6%) patients; their BMD gains, baseline age and treatment duration were not significantly different from those in the other patients. Tolerance was good. CONCLUSION: Pamidronate with physiotherapy and orthopedic management improved outcomes without delaying fracture healing in 19 (70%) of 27 patients. Delayed fracture healing occurred in 8/27 patients. Pamidronate should be reserved for severe OI with multiple fractures and/or flattened vertebras.

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.

Pamidronate in children with osteogenesis imperfecta: histomorphometric effects of long-term therapy.

CONTEXT: Intravenous pamidronate treatment is beneficial to children and adolescents with osteogenesis imperfecta (OI), but the effects of prolonged therapy are not well characterized. OBJECTIVE: The objective of this study was to assess the effect of long-term pamidronate treatment on the bone tissue of children and adolescents with OI. DESIGN: This is an observational study on OI patients receiving iv pamidronate for more than 4 yr. SETTING: The study was carried out in a pediatric metabolic bone research unit. PATIENTS: Patients were 25 moderately to severely affected OI patients (seven girls) aged 1.4-15.3 yr at baseline. INTERVENTION: Intervention was cyclical iv pamidronate at a dose of 9 mg/kg.yr. MAIN OUTCOME MEASURES: Iliac bone biopsy and lumbar spine bone mineral density measures were obtained at treatment start, after 2.7 +/- 0.5 yr (mean +/- sd), and after 5.5 +/- 0.7 yr of therapy. RESULTS: Average areal bone mineral density increased by 72% in the first half of the observation period, but by only 24% in the second half. Mean cortical width and cancellous bone volume increased by 87 and 38%, respectively, between baseline and the first time point during treatment (P < 0.001 for all changes). Thereafter, cortical width did not change significantly, but there was a trend (P = 0.06) toward higher cancellous bone volume. Average bone formation rate on trabecular surfaces decreased by 70% after pamidronate treatment was initiated and showed a trend (P = 0.08) toward a further decline in the second part of the study interval. CONCLUSION: The gains that can be achieved with pamidronate treatment appear to be largely realized in the first 2-4 yr.

Increased bone resorption with decreased activity and increased recruitment of osteoblasts in osteogenesis imperfecta type I.

An iliac bone biopsy from an adult male, 58 years of age, with osteogenesis imperfecta type I was studied by bone histomorphometry after double-fluorescence labeling with tetracycline. Low bone mineral density (BMD) of the radius, measured by dual-energy X-ray absorptiometry (DXA) was associated with high levels of urinary deoxypyridinoline and serum bone-specific alkaline phosphatase and osteocalcin. At the tissue level, low cancellous bone volume (BV/TV) was associated with increased eroded surface (ES/BS) and a relatively increased osteoclast number (N.Oc/BS). Osteoid thickness (O.Th) was also decreased as a result of decreased bone matrix synthesis, in terms of decreased osteoblastic activity. However, osteoid surface (OS/BS) and osteoblast surface (ObS/BS), in terms of the number of osteoblasts, were increased. We conclude that the patient showed cancellous osteopenia, which was likely due to increased bone resorption with decreased activity and increased recruitment of osteoblasts.

Cyclic pamidronate infusion improves bone mineralisation and reduces fracture incidence in osteogenesis imperfecta.

UNLABELLED: A prospective open study was performed to determine the efficacy and safety of pamidronate in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta (OI). Intravenous pamidronate was administered at 1.5 mg/kg bi-monthly to six children with OI, over 12-23 months. The number of fractures decreased from median of 3 (range 1-12) to 0 fractures/year (range 0-4) (P<0.05). After 12 months of treatment, there was significant improvement in areal bone mineral density (BMD) z-scores of the lumbar spine from median of -2.40 (range -3.20 to -1.67) to -1.90 (range -2.38 to -0.91) (P<0.05) and in the volumetric BMD which increased from median of 0.095 to 0.146 g/cm3 (P<0.05). Urine N-telopeptide levels (bone resorption marker) decreased from a median of 461.5 bone collagen equivalent/creatinine (BCE/Cr) (range 129-721 BCE/Cr) to 223.5 BCE/Cr (range 107-312 BCE/Cr) (P<0.05) and serum alkaline phosphatase (ALP) (bone formation marker) from a median of 230.0 U/l (range 148-305 U/l) to 133.5 U/l (range 79-233 U/l) (P<0.05), reflecting reduced bone turnover. This may represent a net reduction in bone resorption and provides a biochemical explanation for the increase in bone mineralisation. Height standard deviation scores were not affected and there were no significant adverse effects. CONCLUSION: 1 year cyclical pamidronate is effective and safe in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta.

Variations in human urinary O-hydroxylysyl glycoside levels and their relationship to collagen metabolism.

Two O-hydroxylysyl glycosides, Hyl-Gal-Glc and Hyl-Gal, have been isolated from normal human urine and shown to be identical to two glycosides isolated from alkaline hydrolysates of collagen. A relatively sample and reproducible analytical procedure has been devised to measure the levels of these glycosides in human urine. By the use of this procedure it was shown that a normal diet has only a small effect on 24-hr urinary excretion levels of these glycosides indicating an endogenous origin. Urinary glycoside levels appear to be highest in children, roughly paralleling collagen turnover as indicated by urinary hydroxyproline levels. Collagen turnover equivalents calculated from urinary hydroxylysyl glycoside levels were found to be significantly larger than collagen turnover equivalents calculated from urinary hydroxyproline levels. This suggests that urinary glycosides are more quantitative indicators of collagen metabolism than urinary hydroxyproline. The ratio of Hyl-Gal-Glc to Hyl-Gal was measured in urines of diseased as well as normal individuals and a bimodal distribution was found. Alkaline hydrolysates of different human connective tissue collagens showed that only bone collagen, of the collagens examined, had a low ratio of Hyl-Gal-Glc to Hyl-Gal compared to human urine. Other collagens examined had higher ratios than found in human urine. On the basis of these results it is postulated that the bimodal distribution of glycoside ratios represents two populations of collagen turnover, the lower ratio population having a high bone collagen turnover, the lower ratio population having a high bone collagen turnover relative to the second population. Examination of the types of subjects making up the two populations supports this hypothesis. These data suggest that urinary O-hydroxylysyl glycoside excretion, in addition to providing a more quantitative estimate of collagen turnover than urinary hydroxyproline, may prove to be of value as a specific means of studying the metabolism of bone collagen.