Warning: Undefined variable $zfal in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Deprecated: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 530
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 531
Warning: file_get_contents(http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=15070910&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 445
 
English Wikipedia
Nephropedia Template TP (
Twit Text
DeepDyve
Pubget Overpricing |  
lüll
Decreased bone turnover and deterioration of bone structure in two cases of pycnodysostosis Fratzl-Zelman N; Valenta A; Roschger P; Nader A; Gelb BD; Fratzl P; Klaushofer KJ Clin Endocrinol Metab 2004[Apr]; 89 (4): 1538-47Pycnodysostosis is an uncommon human genetic disorder characterized by osteosclerosis of the skeleton, short stature, and bone fragility. The disease results from mutations in the cathepsin K gene, a lysosomal cysteine protease highly expressed in osteoclasts and crucial for the degradation of organic matrix from mineralized bone. Recently, interest has focused on a pharmaceutical inhibition of cathepsin K to prevent bone loss. However, little is known about the cellular activity or material quality of bone in pycnodysostosis. In the present study, transiliac bone biopsies from two affected individuals, aged 5 and 21 yr, were investigated using light microscopy, quantitative backscattered electron imaging, and small angle x-ray scattering. Results were compared with published age-matched reference data. The mutations in the cathepsin K gene of both patients were identified, including one novel defect. Both individuals had severe osteosclerosis, and their biopsies displayed multinucleated osteoclasts apposed to areas of demineralized matrix as well as bone-lining cells adjacent to this undigested collagen left over by osteoclasts. The homogeneity of the mineralized matrix was markedly disturbed due to large inclusions of mineralized cartilage residues. Histomorphometric evaluation showed a quantitative decrease in static parameters of bone formation. In contrast and despite deficient cathepsin K activity, osteoclastic parameters were close to normal range. At the nanostructural level, there was a marked increase in the mean thickness of the mineral particles, reflecting decreased bone remodeling. Examination of the trabecular structure revealed that the lamellae were highly disordered, which was also apparent from a poor alignment of mineral crystals oriented along the longitudinal axis of collagen fibrils. Taken together, these results strongly suggest that functional cathepsin K is important for balanced bone turnover, and enzyme deficiency results in a profound deterioration of bone quality with respect to trabecular architecture and lamellar arrangement, which is presumably the reason for bone fragility in pycnodysostosis.|*Bone Remodeling[MESH]|Adult[MESH]|Bone Density[MESH]|Bone Matrix/pathology[MESH]|Bone Resorption/pathology/physiopathology[MESH]|Cartilage/pathology[MESH]|Cathepsin K[MESH]|Cathepsins/genetics[MESH]|Child, Preschool[MESH]|Dysostoses/*diagnosis/genetics/*physiopathology[MESH]|Female[MESH]|Humans[MESH]|Ilium/*diagnostic imaging/*pathology[MESH]|Male[MESH]|Microscopy, Electron, Scanning[MESH]|Mutation[MESH]|Osteoclasts[MESH]|Osteosclerosis/diagnostic imaging/pathology[MESH]|Radiography[MESH]|X-Ray Diffraction[MESH] |
