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At least 505 records · Page 28Linked to original sources
PubMed1998

Role of the subchondral vascular system in endochondral ossification: endothelial cells specifically derepress late differentiation in resting chondrocytes in vitro.

Endochondral ossification in growth plates proceeds through several consecutive steps of late cartilage differentiation leading to chondrocyte hypertrophy, vascular invasion, and, eventually, to replacement of the tissue by bone. It is well established that the subchondral vascular system is pivotal in the regulation of this process. Cells of subchondral blood vessels act as a source of vascular invasion and, in addition, release factors influencing growth and differentiation of chondrocytes in the avascular growth plate. To elucidate the paracrine contribution of endothelial cells we studied the hypertrophic development of resting chondrocytes from the caudal third of chick embryo sterna in co-culture with endothelial cells. The design of the experiments prevented cell-to-cell contact but allowed paracrine communication between endothelial cells and chondrocytes. Under these conditions, chondrocytes rapidly became hypertrophied in vitro and expressed the stage-specific markers collagen X and alkaline phosphatase. This development also required signaling by thyroid hormone in synergy. Conditioned media could replace the endothelial cells, indicating that diffusible factors mediated this process. By contrast, smooth muscle cells, fibroblasts, or hypertrophic chondrocytes did not secrete this activity, suggesting that the factors were specific for endothelial cells. We conclude that endochondral ossification is under the control of a mutual communication between chondrocytes and endothelial cells. A finely tuned balance between chondrocyte-derived signals repressing cartilage maturation and endothelial signals promoting late differentiation of chondrocytes is essential for normal endochondral ossification during development, growth, and repair of bone. A dysregulation of this balance in permanent joint cartilage also may be responsible for the initiation of pathological cartilage degeneration in joint diseases.

Alkaline Phosphatase↗
PubMed2004

Healing of maxillary alveolus in transport distraction osteogenesis for partial maxillectomy.

PURPOSE: This study aims to evaluate histologic healing of the new bone and soft tissue in the distraction gap of maxillary alveolus after transport distraction at different consolidation intervals. MATERIALS AND METHODS: In a monkey model, dentoalveolar segment was distracted backward to a surgical defect in the posterior maxilla with an internal distractor at a rate of 1 mm/day for 2 weeks. The distracted dentoalveolar processes were harvested at 1, 2, and 3 months of consolidation after the completion of distraction. Histologic examination included the new bone, gingiva of the distraction gap, and teeth carrying the transport segments. Tartrate-resistant acid phosphatase was used to assess the presence of osteoclasts in the new bone. The collagen type and expression of bone morphogenetic proteins (BMPs) in the new bone were assessed by immunohistochemistry. RESULTS: The histology confirmed new bone bridging the distraction gap at 1 month of consolidation. Woven bone was progressively replaced by mature lamellar bone at the second and third months. The gingiva covering the distraction gap was of normal appearance. There were no pathologic pulpal changes noted in the transport segment. Tartrate-resistant acid phosphatase-positive osteoclasts were minimal in the new bone. The mode of ossification was confirmed as intramembranous, and the fibrous stroma consisted mainly of collagen type I. At 1 month of consolidation, the BMPs were expressed profusely in the fibrous matrix and also inside the fibroblasts and osteoblasts. At 2 and 3 months of consolidation, the BMP expression intensity was reduced significantly in the fibrous stroma. CONCLUSIONS: The study confirmed that the bone regenerate in maxillary transport distraction was formed by intramembranous ossification and teeth in the transport segment remain viable after maxillary transport distraction osteogenesis.

Alveolar Process↗
PubMed2001

Role of the subchondral vascular system in endochondral ossification: endothelial cell-derived proteinases derepress late cartilage differentiation in vitro.

Endochondral ossification in growth plates proceeds through several consecutive steps of late cartilage differentiation leading to chondrocyte hypertrophy, vascular invasion, and, eventually, to replacement of the tissue by bone. The subchondral vascular system is essential for this process and late chondrocyte differentiation is subject to negative control at several checkpoints. Endothelial cells of subchondral blood vessels not only are the source of vascular invasion accompanying the transition of hypertrophic cartilage to bone but also produce factors overruling autocrine barriers against late chondrocyte differentiation. Here, we have determined that the action of proteases secreted by endothelial cells were sufficient to derepress the production of the hypertrophy-markers collagen X and alkaline phosphatase in arrested populations of chicken chondrocytes. Signalling by thyroid hormones was also necessary but endothelial factors other than proteinases were not. Negative signalling by PTH/PTHrP- or TGF-beta-receptors remained unaffected by the endothelial proteases whereas signalling by FGF-2 did not suppress, but rather activated late chondrocyte differentiation under these conditions. A finely tuned balance between chondrocyte-derived signals repressing cartilage maturation and endothelial signals promoting late differentiation of chondrocytes is essential for normal endochondral ossification during development, growth, and repair of bone. A dysregulation of this balance in permanent joint cartilage also may be responsible for the initiation of pathological cartilage degeneration in joint diseases.

Alkaline Phosphatase↗
PubMed1975

Observations on the pathology of bent leg of lambs in South-Western Queensland.

This paper presents the first radiological and pathological description of bent leg, a disease of lambs occurring in the mulga country of south-western Queensland and thought to be caused by plants of the genus Trachymene. In the 5 field cases studied, the deformed limbs were characterised by abnormal diaphyseal curvatures and altered angulation of articular surfaces. There was both radiological and pathological evidence of irregular retardation of growth of epiphyseal plates. It was suggested that ingestion of toxic plant by the ewe interferes with normal endochondral ossification in the foetus. It was further suggested that more severely affected lambs probably occur but do not survive until marking.

Animals↗
PubMed1977

Pilomatrixoma (calcifying epithelioma of Malherbe): radiographic features.

Pilomatrixomas (calcifying epitheliomas of Malherbe) are benign soft-tissue tumors that occur in the dermis or subcutaneous tissues; about 40% are found in children under 10 years of age. More than 80% have microscopic calcification and/or ossification. Although the incidence of radiographically visible calcification is not known, heavily calcified tumors have a distinctive radiographic appearance. The authors describe the radiographic and pathologic findings in 2 children with pilomatrixomas.

Calcinosis↗
PubMed2005

Spondylitic changes in long-finned pilot whales (Globicephala melas) stranded on Cape Cod, Massachusetts, USA, between 1982 and 2000.

The primary bone pathology diagnoses recognized in cetacea are osteomyelitis and spondylosis deformans. In this study, we determined the prevalence, type, and severity of vertebral pathology in 52 pilot whales, a mass stranding species that stranded on Cape Cod, Massachusetts, between 1982 and 2000. Eleven whales (21%) had hyperostosis and ossification of tendon insertion points on and between vertebrae, chevron bones, and costovertebral joints, with multiple fused blocks of vertebrae. These lesions are typical of a group of interrelated diseases described in humans as spondyloarthropathies, specifically ankylosing spondylitis, which has not been fully described in cetacea. In severe cases, ankylosing spondylitis in humans can inhibit mobility. If the lesions described here negatively affect the overall health of the whale, these lesions may be a contributing factor in stranding of this highly sociable species.

Animals↗
PubMed1999

Unilateral sensorineural hearing loss and its aetiology in childhood: the contribution of computerised tomography in aetiological diagnosis and management.

OBJECTIVES: The objective of this study was to identify factors correlated with the CT outcome and to examine the contribution of the CT scan in the aetiological diagnosis and management of unilateral sensorineural hearing loss in childhood. METHODS: The records of 35 consecutively investigated patients by the Audiology Department of Great Ormond Street Hospital between January 1996 and June 1998 were reviewed. The CT results, population sample characteristics, initiation of further investigations after the CT results and management decisions based on the CT results were tabulated and analysed. RESULTS: In a series of 35 consecutively investigated children with unilateral sensorineural hearing loss, 11 CT scans were identified as abnormal. The CT findings were: labyrinthitis ossificans (3), unilaterally dilated vestibular aqueduct (2), bilaterally dilated vestibular aqueduct (2), unilateral deformity of the cochlea ('Mondini') (1), unilateral severe labyrinthine dysplasia (1), unilateral markedly narrow internal acoustic meatus (1), bilaterally dilated lateral semicircular canals (1). The presence of progressive hearing loss was a significant predictor of abnormal CT outcome, while the severity of hearing loss was not. The CT scans offered valuable information regarding the aetiological diagnosis in all cases and, in addition, prompted the appropriate vestibular rehabilitation in three cases, further investigations in four (with dilated vestibular aqueduct) and hearing preservation counselling in two (bilateral DVA) (seven out of 35 = 20%). CONCLUSION: All children with unilateral sensorineural hearing loss should have a CT scan of the petrous pyramids/IAMs performed at some stage, as not only aetiology but also prognosis and management of these cases may be significantly influenced by the CT outcome.

Adolescent↗
PubMed1991

Fibrocartilaginous mesenchymoma of bone.

Two bone tumors in children were characterized by prevalent low-cellular fibrous stroma of mature appearance and lobules of hyaline cartilage or chondroid tissue. Endochondral ossification was an additional finding. Clinically the two cases presented with osteolytic lesions of considerable size and relapsing course thus enhancing the suspicion of malignancy. The pathological diagnosis was controversial but both patients are disease-free several years after diagnosis. Histopathologically, the process duplicated the consecutive steps of embryonal endochondral bone formation. In a review of the pertinent literature it was found that these two cases reflect to a large extent the bone lesion reported in 1984 by Dahlin et al. and designated fibrocartilaginous mesenchymoma of the bone.

Bone Neoplasms↗
PubMed1978

Meningioma in a dog.

The history, clinical signs and pathological findings in a 9-year-old Labrador dog with an intracranial tumour, are described. The tumour conformed to the rare meningiothelial meningioma with focal ossification.

Animals↗
PubMed1994

[Clinicopathologic analysis of ossification in spinal meningioma].

Calcification such as psammoma body is sometimes found especially in spinal cord meningioma but ossification of the meningeal tumor was rarely observed. Two cases of ossificated spinal cord meningiomas, located extramedullary intradurally apart from spinal bone, were clinicopathologically analyzed. The patients were 75-year-old female with meningioma at T9-10 level and 60-year-old female with one at T6-8 level. With pathological examination, concentration of psammoma bodies is not related to the formation of bone tissue. Metaplasia of arachnoid cell is seemed to be the origin of the bone structure.

Aged↗
PubMed1975

Osteopetrosis fetalis. Report on a case, with special reference to ultrastructure.

The clinical and pathological findings concerning the skeletal abnormalities in a case of osteopetrosis fetalis have been reported. The principal data can be summarized as follows. The areas of endochondral ossification have a rickety appearance because of excessive number of hypertrophic and degenerate chondrocytes. These cells are highly vacuolated and the vacuoles, which are of mitochondrial origin, contain beaded filaments which are exocytosed and become part of the matrix. The calcification process is delayed, probably in consequence of a reduced number of matrix vesicles. Abnormal collagen fibrils are sometimes present in the cartilage. The osteoclasts have a very low reabsorbing activity and appear structurally abnormal. The combined effect of all these abnormalities leads to excessive development of osteocartilaginous trabeculae in marrow spaces. These trabeculae have a Ca/P ratio of 1.79 and their mineral substance appears qualitatively normal under the electron microscope.

Bone and Bones↗
PubMed2001

Intracapsular and para-articular chondroma adjacent to large joints: report of three cases and review of the literature.

Para-articular chondroma is a rare tumor that has been reported in only 30 cases adjacent to large joints in the Anglo-Saxon literature. We report three new cases of this entity, describe its clinical, radiological and pathological features, and review the previous literature. Para-articular chondromas have an insidious clinical presentation and on radiographs show a large soft tissue mass with variable ossification. They appear as a lobulated mass of hyaline cartilage with variable endochondral ossification in the central area. These rare benign tumors arise from the capsule or the para-articular connective tissue of a large joint (mainly the knee), which suffers cartilaginous metaplasia and subsequent ossification. Cases 1 and 2 of this presentation fit all the features described previously. Case 3 has identical clinical features but differs from the former two cases in its microscopic appearance, being composed almost entirely of fibrocartilage and myxoid areas within the fibroadipose tissue of the joint instead of mature trabecular bone surrounded by hyaline cartilage. To the best of our knowledge this is the first description of this histological variant of para-articular chondroma.

Adult↗
PubMed1996

[A case of diffuse idiopathic skeletal hyperostosis (DISH) with various neurological complications].

A 71-year-old female presented with a 10-year history of slowly progressive gait disturbance and dorsolumbar pain. Motion of he neck and trunk was severely restricted. She showed decreased sensation of vibration and position in the upper and lower limbs and had Romberg's sign. Hyperesthesia of touch sensation was distributed in a stocking pattern. She showed hyporeflexia and pathological reflexes in lower limbs. Her gait was ataxic and spastic. Laboratory examination of blood and urine revealed no remarkable findings. Radiographic examination revealed ligamentous calcification and ossification along the anterolateral aspect of the vertebral column at several levels, and there was ossification of hte ligament and tendon attachment to the bone at extraspinal sites. The radiographic features were characteristic of diffuse idiopathic skeletal hyperostosis (DISH). Computed tomography at lower thoracic and lumbar vertebral portions showed compression of the spinal cord by ossification of the flavatum ligament. The conduction velocity of tibial nerves and sural nerves were delayed, and the mechanism of the occurrence of peripheral nerve lesions in this patient could be explained by extrinsic compression by heterotopic calcification or some metabolic factor due to DISH.

Aged↗
PubMed1999

Shoulder arthroplasty. Indications, contraindications and complications.

Prosthetic substitution of the glenohumeral joint, begun at the end of the last century, has developed greatly in recent years. Today the most widely used shoulder prostheses are defined as "modular" because of their extensive adaptability. The capacity to adapt to anatomic variations must be incorporated within their structure, and normal articular biomechanics must be respected. The choice of prosthesis must be based on the condition of the joint surfaces, on the anatomic and functional condition of the rotator cuff. So endoprosthesis of the shoulder is indicated for avascular necrosis of the head of the humerus, fractures and pseudoarthrosis of the extreme proximal end of the humerus, arthropathy following rotator cuff rupture. Total shoulder prosthetization is indicated for glenohumeral osteoarthritis, rheumatoid arthritis and outcomes of endoprosthesis. The principal contraindications for shoulder replacement include an infection in progress, Charcot's arthropathy and severe neurological pathologies. The complications of shoulder prostheses include infection, dislocation, loosening of a component, periprosthetic humeral and glenoid fractures, nerve injuries, fractures of a prosthetic component and ectopic ossification. At present prosthetic substitution of the glenohumeral joint offers good results. Indispensable conditions for these results include anatomic and functional integrity of the musculature, good bone quality, correct positioning of the prosthetic components and a proper rehabilitation program.

Arthroplasty, Replacement↗
PubMedDate not supplied

The benign fibroosseous lesion: its association with paranasal sinus mucoceles and its MR appearance.

Although fibrous dysplasia and ossifying fibroma of the facial bones may, with some difficulty, be distinguishable pathologically, they are inseparable radiographically. Based on a study of 30 patients, there was no good or reliable imaging correlation with the histology and the degree of ossification or the bone(s) involved. Therefore, "benign fibroosseous lesion" has been proposed by several noted bone authorities as the term for these entities. Eleven patients had MRI and the overall signal intensities were low on both T1-weighted and T2-weighted sequences. Areas of high signal intensity on T2-weighted imaging correlated with either cysts within the lesion or the presence of mucocele, especially in the frontoethmoid region. Four such mucoceles are presented. The coexistence of mucoceles and benign fibroosseous lesions may be more common than previously reported. It is both realistic and appropriate for the radiologist to diagnose these entities as benign fibroosseous lesions and leave the final histologic diagnosis to the pathologist who can diagnose most such cases, albeit with some difficulty. Sites of high signal intensity on T2-weighted imaging in the frontoethmoid area should raise the possibility of a coexistent mucocele.

Adolescent↗
PubMed1977

[On the differential diagnosis of shadows due to calcigerous soft tissue in the extremities (author's transl)].

We report a case of an unusual compact limy shading of the soft part in the lower leg, obviously caused by unphysique material the origin of which even retrospectively could not be clarified. Pathological compact limy shadings of the soft parts of the extremities are possible because of numerous reasons. Hereby the tissue calcination will be defined from the real ossifications and the direct exogene shades. Deficient knowledge of the pathophysiology often makes a preoperative difference very difficult with equivalent reoentgenological statements. The own difficulties in diagnosis of the case in question will be shown.

Adult↗
PubMed1995

Radiologic manifestations of osteopetrosis.

The clinical radiologic manifestations of 8 patients with osteopetrosis (4 males and 4 females) are analyzed. Six of the cases are benign. The pathologic basis for the radiologic manifestations is discussed, and a classification is suggested. "Broom-like" metaphyses, metaphyses containing three or four dense layers of bone, and ossification of soft tissues around joints were found and differential diagnosis was made.

Adolescent↗