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1,25-Dihydroxyvitamin D3 and 22-oxa-1,25-dihydroxyvitamin D3 in vivo nuclear receptor binding in developing bone during endochondral and intramembranous ossification.

Target cells for 3H-labeled 1 alpha, 25(OH)2 vitamin D3 [1,25(OH)2D3, vitamin D] and its analog 3H-labeled 22-oxa-1 alpha, 25(OH)2 vitamin D3 (OCT) have been identified during endochondral and intramembranous ossification in developing, undecalcified, unembedded bone, using thaw-mount autoradiography. Two-day-old neonatal rats were injected with [3H]1,25(OH)2D3 or [3H]OCT; after 2 h leg, spine, and head were frozen and sectioned. In the epiphyseal-metaphyseal region specific nuclear concentrations of [3H]1,25(OH)2D3 and [3H]OCT were observed in identical cell populations, being low in cells of the articular and resting zone, intermediate in the proliferating zone, and highest in hypertrophic chondrocytes and in osteoblasts and precursor cells. In the primary spongiosa intertrabecular spaces there were a large number of cells with nuclear labeling--probably osteoblasts and precursor cells. In contrast, in the secondary spongiosa intertrabecular spaces, apparent blood-forming cells were mostly unlabeled. Osteoblasts along bone spicules and compact bone in long bones, vertebrae, and head also showed strong nuclear labeling, as did cells of the periosteum. These data suggest that 1,25(OH)2D3 and OCT regulate development, differentiation, and activities of chondrocytes and osteoblasts, including differentiation of resting chondrocytes into proliferating and hypertrophic chondrocytes that involve "chondroclastic" enlargement of lacunae and "trans-differentiation" of surviving hypertrophic chondrocytes; differentiation of stroma cells into osteoblasts; and in periosteum and other regions of intramembranous ossification differentiation of precursor cells and osteoblasts. Nuclear receptor binding and their selective and hierarchical distribution during cell differentiation appear to correspond to multiple genomic effects toward growth, regeneration and repair. The findings indicate a physiological significance and therapeutic potential of 1,25(OH)2D3 and in particular of its less hypercalcemic analog OCT.

Animals↗

Biochemical and histological sequences of membranous ossification in ectopic site.

Porous hydroxyapatite ceramics alone (control) and ceramics combined with rat marrow cells were implanted subcutaneously in the back of syngeneic rats and harvested 1-8 weeks after implantation. The ceramics were examined biochemically and histologically. Alkaline phosphatase activity in the marrow cell/ceramic composites began to increase at 2 weeks and achieved a peak at 4 weeks, followed by a gradual decrease. Bone gla protein contents in the composites began to increase at 3 weeks and steadily increased as time passed. Histologically, osteoblastic cells were detected at 2 weeks and obvious de novo bone together with active osteoblasts began to appear at 3 weeks in the composites. The process was membranous ossification without cartilage formation and was observed in the pores of the composites. The pore areas occupied by bone increased as time passed. In contrast, ceramics alone did not show any bone formation and contained traces of these biochemical parameters. These results indicated that the biochemical sequences correlate with the histological sequences in the heterotopic membranous ossification.

Alkaline Phosphatase↗

A radiological population study on the ossification of the posterior longitudinal ligament in the spine.

This paper reports the results of a radiological population study on the ossification of the posterior longitudinal ligament (OPLL) in both the cervical and the thoracic spine among Japanese. The study was carried out in the Yachiho-mura district in the central part of Japan, where 5074 people were living. X-ray examinations were made of 1058 of the people; there were 440 men and 618 women, 50 or more years of age. The roentgenograms showed 34 cases of OPLL in the cervical spine (3.2%): 19 men (4.3%) and 15 women (2.4%). The condition was most frequently observed at the level of C-4. Radiological classification showed 18 cases of the segmental type, 11 of the continuous type, and five of a mixed type. There were eight cases of OPLL in the thoracic spine (0.8%), four in men (0.9%) and four in women (0.6%). OPLL in the thoracic spine was most frequently observed at the midthoracic levels. All eight cases showed a continuous type of ossification. There were three subjects with OPLL in both the cervical and the thoracic spine. Therefore, the number of subjects with OPLL in either the cervical or the thoracic spine was 39 (3.7%) total.

Aged↗

Para-articular ossification in total hip replacement: an indication for irradiation therapy.

The results of postoperative irradiation therapy after total hip replacement or resection of para-articular ossification in 25 patients are reported. The patients were kept under radiological observation for an average period of 26 months and clinical observation for an average period of 31 months after surgery. There were only two clinically relevant recurrences of para-articular ossification. The earlier radiotherapy with a total dose of 2000 rads (2000 cGy) was begun, the better was the effect. In this small population sample statistical significance could not be calculated. No side effects were detected.

Adult↗

Radiotherapy in the prevention of recurrence of paraarticular ossification in total hip prostheses.

Ectopic bone formation or paraarticular ossification after total hip arthroplasty can be a very disabling factor. In patients with this problem, range of motion and walking ability may be reduced and pain can occur. In severe cases it seems logical to remove this paraarticular ossified tissue, but without measures to prevent its recurrence this will be of no real value. This study shows the effectiveness of irradiation soon after excision of the ectopic bone mass, with a total dosage of 20 Gy (2000 rad) given in ten fractions, in preventing, or at least inhibiting, the recurrence of paraarticular ossification in 16 patients. A dramatic improvement in hip function, walking ability, and relief of pain is demonstrated.

Aged↗

A new familial skeletal dysplasia with severely retarded ossification and abnormal modeling of bones especially of the epiphyses, the hands, and feet.

Three brothers with a constitutional skeletal dysplasia characterized by an excessively retarded ossification, principally of the epiphyses, the pelvis, the hands and the feet, are reported. In the hands and feet the retarded ossification is combined with an abnormal modeling of the bones. All the children appeared normal at birth. At the time of examination a moderate degree of dwarfism could be predicted. There was no mental retardation. All laboratory investigations including chromosomal analyses and examination for acid mucopolysaccharides in the urine were normal. Parental consanguinity suggest an autosomal recessive inheritance. There is no resemblance of this disorder to any of the hitherto described groups of constitutional diseases of bones.

Bone Diseases, Developmental↗

Humeral head and coracoid ossification in Nigerian newborn infants.

The presence of the coracoid and proximal humeral head epiphysis in 201 Nigerian newborn infants was related to gestational age. The appearance of the humeral head of ossification centre was delayed, while the coracoid epiphysis appeared earlier than those of Caucasian newborn infants. There was no difference in the pattern of epiphyseal ossification between the sexes.

Epiphyses↗

Localization of collagens and alkaline phosphatase activity during mineralization and ossification of human first rib cartilage.

The localization of type X collagen and alkaline phosphatase activity was examined in order to gain a better understanding of tissue remodelling during development of human first rib cartilage. First rib cartilages from children and adolescents showed no staining for type X collagen and alkaline phosphatase activity. After onset of mineralization in the late second decade, a peripheral ossification process preceded by mineralized fibrocartilage could be distinguished from a more central one preceded by mineralized hyaline cartilage. No immunostaining for type X collagen was found in either type of cartilage. However, strong staining for alkaline phosphatase activity was detected around chondrocyte-like cells within fibrocartilage adjacent to the peripheral mineralization front, while a weaker staining pattern was observed around chondrocytes of hyaline cartilage near the central mineralization front. In addition, the territorial matrix of some chondrocytes within the hyaline cartilage revealed staining for type I collagen, suggesting that these cells undergo a dedifferentiation process, which leads to a switch from type II to type I collagen synthesis. The study provides evidence that mineralization of the hyaline cartilage areas in human first rib cartilage occurs in the absence of type X collagen synthesis but in the presence of alkaline phosphatase. Thus, mineralization of first rib cartilage seems to follow a different pattern from endochondral ossification in epiphyseal discs.

Adolescent↗

Animal model of experimentally induced ectopic enchondral ossification in nude mice with xenograft of porcine epiphyseal cartilage.

In a specific animal model the induction of heterologous enchondral ossification was examined in long term follow-up. Physiologically normal and devitalized frozen porcine epiphyseal cartilage as a control group were transplanted as s.c. xenograft into athymic nude mice (nu/nu). 15 weeks after transplantation the porcine growth plate cartilage showed the development of viable cartilage tissue in the recipients, further differentiating to juvenile long bone with epiphysis, diaphysis and growth plate. Porcine growth plate cartilage increased s.c. in the recipient nude mice, showing enchondral ossification without any physiological load, and finally an unexpected development towards complete juvenile long bone.

Animals↗

Effect of ethane-1-hydroxy-1,1-bisphosphonate (EHBP) on endochondral ossification lesions induced by a lethal oral dose of uranyl nitrate.

A 350 mg/kg body weight (b.w.) oral dose of uranyl nitrate (UN) caused 100% mortality in mice three days after administration, due to resulting kidney lesions. Mortality decreased 50% after an oral (o) or subcutaneous (sc) dose of bisodic etidronate (EHBP). Given that bone is also a target organ for uranium (U) in acute intoxication, the aim of this work was to study the effect of exposure to a lethal oral dose of UN on endochondral ossification, and the latter's response to EHBP treatment. One hundred male Balb/c mice weighing 25 g were assigned to one of ten groups. Group I served as control. Group II received a lethal 350 mg/kg b.w. oral dose of UN by gavage. Groups III, IV, VII, and VIII received an equal dose of UN immediately followed by a single 500 mg/kg oral dose of EHBP in groups III and VII and a single 50 mg/kg subcutaneous dose of EHBP in groups IV and VIII. Groups V and IX only received a single 500 mg/kg oral dose of EHBP, and groups VI and X received a single 50 mg/kg subcutaneous dose of EHBP. The animals in groups II, III, IV, V, and VI were sacrificed 48 h after the onset of the experiment, whereas those in groups VII, VIII, IX, and X were killed at 14 days. Histologic and histomorphometric studies were performed on the femurs to determine growth cartilage width, bone volume, and metaphyseal bone activity. Our results showed that all growth cartilage and metaphyseal bone histomorphometric parameters were significantly lower in animals exposed to UN at 48 h than in controls. EHPB administration was found to prevent this condition at 48 h reaching similar values to those of controls. Although histomorphometric values did not reach control values at 14 days, they were higher than those of animals exposed to UN at 48 h not treated with EHBP. It is noteworthy that these values also decreased in animals only receiving EHBP at 14 days. Our results show that EHBP effectively ameliorates the adverse effects of a lethal dose of UN on endochondral ossification.

Administration, Oral↗

The role of chondrocytes in intramembranous and endochondral ossification during distraction osteogenesis in the rabbit.

We have used a rabbit leg-lengthening model for detailed studies of the histology of distraction osteogenesis. Some unusual features of the endochondral ossification that occurs during the rapid transition of cartilage to bone in the regenerate were observed. Histological staining techniques together with immunohistochemistry and nonradioactive in situ mRNA hybridization for cartilage and bone-related molecules have been used to document the presence of an overlapping cartilage-bone phenotype in cells of the cartilage-bone transitional region. In those particular areas, some chondrocytes appeared to be directly transformed into newly formed bone trabeculae which are surrounded by bone matrix. Acid phosphatases were found within the cartilage matrix in some of the cartilage/bone transitional regions and type I collagen mRNA and type II collagen protein were found together in some of the marginal hypertrophic chondrocytes. This study indicates an unusual role of chondrocytes in the process of ossification at a distraction rate of 1.3 mm/day in the rabbit. Further direct evidence is required to prove the hypothesis that the hypertrophic chondrocytes may transdifferentiate into bone cells in this model.

Acid Phosphatase↗

Ellis-van Creveld syndrome: a generalized dysplasia of enchondral ossification.

We report a 25-week fetus with lethal Ellis-van Creveld syndrome who was diagnosed prenatally from the US detection of a narrow chest, postaxial polydactyly of the hands, short acro-/mesomelic limbs and a ventricular septal defect. The postnatal radiographic features of the skeleton confirmed the diagnosis. Literature review of the histopathology of the physeal growth plate is contradictory, varying between retardation of the hypertrophic chondrocytes without disorganization and marked disorganization of the proliferating chondrocytes. We investigated numerous sites of the enchondral ossification and observed retardation of the physeal growth plate in all sites and retardation with pronounced disorganization of the physeal growth plate in the upper mesomelic bone segments only. These data support the concept that Ellis-van Creveld syndrome is mainly a generalized disorder of the maturation of enchondral ossification.

Adult↗

Studies on the time frame for ossification of the medial epiphysis of the clavicle as revealed by CT scans.

The authors retrospectively analyzed 629 CT images of patients aged between 15 and 30 years produced during multiple trauma diagnostics at the Unfallkrankenhaus Berlin. For the purposes of this study, the authors reliably determined the ossification status of the medial epiphysis of the clavicle in 556 cases, using the classification of stages by Schmeling et al. In both sexes, stage 2 was first noted at age 15. In male patients, the earliest occurrence of stage 3 was noted at age 17, in female patients at age 16. Stage 4 was first achieved by both sexes at age 21. Stage 5 was first noted in female patients at age 21 and in male patients at age 22, which is 4 or 5 years earlier than was observed by a comparable study using conventional radiographs. The partial-volume effect in computed tomography using the thick slice scanning mode was discussed as a possible explanation for this early visualization. The question of how slice thickness affects the age intervals between ossification stages identified by CT examinations should be examined in additional studies.

Adolescent↗

Immunohistochemical detection of cathepsin D, K, and L in the process of endochondral ossification in the human.

Cathepsins D, K, and L were immunolocalized in tissue undergoing endochondral ossification in the human. Cathepsins D, K, and L were localized in osteoclasts and chondroclasts attached to bone matrix and cartilage matrix, respectively. Cathepsins D and L were immunostained in chondrocytes. Immunolocalization of cathepsin D was limited to hypertrophic chondrocytes adjacent to the osteochondral junction. In contrast, cathepsin L was immunolocalized in both proliferating and hypertrophic chondrocytes. In the bone marrow space, cathepsins D, K, and L were localized in multinucleated cells. Cathepsin D was diffusely detected in mononuclear bone marrow cells which were negative for cathepsins K and L. The present findings indicated that cathepsins K, D, and L were associated with the process of endochondral ossification in the human, and suggested that these cathepsins share roles in bone and cartilage turnover in the human.

Bone Marrow↗

Immunohistochemical detection of parathyroid hormone-related peptide, Indian hedgehog, and patched in the process of endochondral ossification in the human.

Parathyroid hormone-related peptide (PTHrP), Indian hedgehog (Ihh), and patched (Ptc; a receptor for Ihh) were immunolocalized in tissue undergoing endochondral ossification in the human. PTHrP, Ihh, and Ptc were immunolocalized in prehypertrophic and hypertrophic chondrocytes in mature cartilage matrix. PTHrP and Ptc were immunostained in proliferating chondrocytes and perichondrial cells, whereas Ihh was not. PTHrP, Ihh, and Ptc showed positive immunostaining in osteoblasts in the bone-forming area. In the bone resorption site, PTHrP was immunolocalized in osteoclasts, whereas Ihh and Ptc were not. The present findings indicated that PTHrP, Ihh, and Ptc were associated with the process of endochondral ossification, and suggested the possible involvement of Ihh and PTHrP signaling in the regulation of proliferation and hypertrophy of chondrocytes in human chondrogenesis.

Bone Neoplasms↗

Complement Cls, a classical enzyme with novel functions at the endochondral ossification center: immunohistochemical staining of activated Cls with a neoantigen-specific antibody.

The secondary ossification center of 14- to 16-day-old hamster tibiae was examined immunohistochemically with active and inactive Cls-specific antibodies, RK5 and RK4, respectively. At the ossification center, chondrocytes differentiate from proliferating and hypertrophic to degenerating stages, and their site is occupied by the bone marrow. Cls was strongly immunostained in hypertrophic chondrocytes. In order to discover whether Cls is activated at a particular site, the cartilage was immunostained with RK5 and RK4. RK5 mainly reacted with degrading matrix around invading vessels. In contrast, RK4 strongly stained hypertrophic chondrocytes. Immunoelectron microscopy revealed Cls on degrading fragments of chondrocytes and fibers of cartilage matrix. Decorin, one of the major matrix proteoglycans, was dose and time dependently degraded by Cls. Type II collagen and type I gelatin were also degraded. Articular cartilage from patients with rheumatoid arthritis was positively immunostained (11/12 cases) with an anti-Cls monoclonal antibody (mAb) PG11, whereas normal articular cartilage (5/5 cases) was negative, suggesting Cls participation in the etiology of rheumatoid arthritis.

Amino Acid Sequence↗

Growth cartilage calcification and formation of bone trabeculae are late and dissociated events in the endochondral ossification of Rana catesbeiana.

Endochondral ossification in the growth cartilage of long bones from the bullfrog Rana catesbeiana was examined. In stage-46 tadpoles and 1-year-old animals, the hypertrophic cartilage had a smooth contact with the bone marrow and the matrix showed no calcification or endochondral bone formation. In spite of showing no aspects of calcification, the chondrocytes exhibited alkaline phosphatase activity and some of them died by apoptosis. However, matrix calcification and endochondral ossification were observed in 2-year-old bullfrogs. Calcium deposits appeared as isolated or coalesced spherical structures in the extracellular matrix of hypertrophic cartilage. Bone trabeculae were restricted to the central area at the sites where the hypertrophic cartilage surface was exposed to the bone marrow. Cartilage matrix calcification and the formation of bone trabeculae were not dependent on each other. Osteoclasts were involved in calcified matrix resorption. These results demonstrate that the calcification of hypertrophic cartilage and the deposition of bone trabeculae are late events in R. catesbeiana and do not contribute to the development and growth of long bones in adults. These processes may play a role in reinforcing bony structures as the bullfrog gains weight in adulthood. In addition, the deposition of bone trabeculae is not dependent on cartilage matrix calcification.

Alkaline Phosphatase↗

On the morphology of the terminal microvasculature during endochondral ossification in rats.

The investigation was carried out on the proximal tibia metaphysis by means of India ink-injection, reconstruction, corrosion casting combined with scanning electron microscopy, and transmission electron microscopy of thin sections. The terminal vasculature during endochondral ossification proved to be a labyrinth of interconnected sinusoidal complexes with bulbous buds invading the chondrocyte cavities of the growth plate. This system of vessels was canalized throughout. A special feature was the existence of endothelial pockets. The formation of the terminal microvasculature as a labyrinthine cavity during endochondral ossification, together with the still incompletely developed bone could be a weak point for compression injuries.

Animals↗