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PubMed2004

Chondrocyte-specific knockout of the G protein G(s)alpha leads to epiphyseal and growth plate abnormalities and ectopic chondrocyte formation.

UNLABELLED: G(s)alpha is a ubiquitously expressed G protein alpha-subunit that couples receptors to adenylyl cyclase. Mice with chondrocyte-specific ablation of the G(s)alpha gene had severe epiphyseal and growth plate abnormalities and ectopic cartilage formation within the metaphyseal region of the tibia. These results show that G(s)alpha negatively regulates chondrocyte differentiation and is the critical signaling mediator of the PTH/PTH-rP receptor in growth plate chondrocytes. INTRODUCTION: G(s)alpha is a ubiquitously expressed G protein alpha-subunit that mediates signaling through G protein-coupled receptors to activate the cAMP/protein kinase A signaling pathway. Although studies suggest an important role for G(s)alpha in regulating growth plate development, direct in vivo results examining this role are lacking. MATERIALS AND METHODS: The G(s)alpha gene was ablated in murine cartilage by mating mice with loxP sites surrounding the G(s)alpha promoter and first exon with collagen 2a1 promoter-Cre recombinase transgenic mice. Skeletal tissues were studied by gross and microscopic pathology, and gene expression was determined by in situ hybridization. RESULTS AND CONCLUSIONS: Mice with complete chondrocyte-specific G(s)alpha deficiency (homozygotes) died within minutes after birth and had severe epiphyseal and growth plate defects with shortening of the proliferative zone and accelerated hypertrophic differentiation of growth plate chondrocytes, a phenotype similar to that of PTH/PTH-related peptide (PTHrP) receptor knockout mice. Indian hedgehog and PTH/PTHrP receptor expression in prehypertrophic chondrocytes was unaffected in mutant mice. PTHrP expression in periarticular cartilage was increased in the mutant mice, probably because of the closer proximity of Ihh-secreting chondrocytes to the periarticular zone. In addition, these mice developed ectopic cartilage at the anterior side of the metaphyseal region in the tibia. Mice with partial G(s)alpha deficiency (heterozygotes) exhibited no phenotype. These results show that G(s)alpha negatively regulates chondrocyte differentiation and is the critical signaling mediator of the PTH/PTHrP receptor in epiphyseal and growth plate chondrocytes.

Animals↗
PubMed1999

"Cell paralysis" as an intermediate stage in the programmed cell death of epiphyseal chondrocytes during development.

The efficient elimination of apoptotic cells depends on heterophagocytosis by other cells, which is difficult or impossible when the dying cells are embedded in an extracellular matrix. This situation is exemplified by the epiphyseal chondrocytes during the development of the chondroepiphyses of long bones. A detailed ultrastructural study identified an unusual type of epiphyseal chondrocyte which contained a very dark nucleus with irregular patches of condensed chromatin and a crenated nuclear membrane. The cytosol consisted of excessively expanded endoplasmic reticulum lumen, containing "islands" of cytoplasm and organelles. Since these cells appeared to be "in limbo," neither viable nor dead, they are referred to as "paralyzed" cells. By studying cells of intermediate morphologies, we were able to demonstrate the sequence of events leading to cell paralysis. It is proposed that the paralysis represents an intermediate state in the physiological cell death of epiphyseal chondrocytes in which destruction is orderly and avoids a inflammatory, potentially locally destructive, reaction. The cell is rendered paralyzed in terms of function but impotent in respect of damaging consequences. Paralysis is compared and contrasted with apoptosis, autophagocytosis, and necrosis and may represent another mode of programmed cell death in situations where cells are immature and/or where phagocytosis by neighboring cells is difficult.

Animals↗
PubMedDate not supplied

Human studies on the biological actions of IGF-1. Evidence suggesting that human fetal and postnatal epiphyseal cartilage is a target tissue for IGF-1 action.

Recent data show that in humans IGF-1 has insulin-like anabolic and growth promoting effects. However, the plasma levels at which IGF-1 exerts these effects differ. IGF-1 plasma levels similar to those in normal children and adults have a growth promoting effect, but higher levels are necessary for IGF-1 to exert insulin-like anabolic effects, and hypoglycemia is a potential risk. Longitudinal bone growth results from the proliferation and differentiation of chondrocytes in epiphyseal cartilage. We present our data from cultured human epiphyseal chondrocytes, which suggest that epiphyseal cartilage may be a target tissue for IGF-1 action during human fetal and postnatal development.

Adult↗
PubMed1989

Demonstration of growth hormone receptors in cultured rat epiphyseal chondrocytes by specific binding of growth hormone and immunohistochemistry.

Growth hormone has been reported to exert direct effects on rat and rabbit epiphyseal chondrocytes in vitro, indicating that GH interacts with specific receptors on these cells. To investigate this possibility, binding of GH to cultured rat epiphyseal chondrocytes was studied under various experimental conditions. Chondrocytes were isolated enzymatically from epiphyseal growth plates of the proximal tibia of 20-day-old male rats and were cultured in monolayer in Ham's F-12 medium supplemented with 10% calf serum and 1% of a serum substitute. The cells were seeded at various densities (25,000-200,000 cells/well) and cultured for 5-16 days. Twenty-four hours before binding experiments, the medium containing calf serum was changed for one containing serum obtained from hypophysectomized rats, in order to avoid binding of GH present in the calf serum. Binding was studied by incubating 125I-labelled human GH (hGH) with the cells in the presence or absence of various concentrations of unlabelled hGH, bovine GH (bGH), rat GH (rGH) and ovine prolactin (oPRL). Specific binding could be demonstrated in cells cultured for 5-16 days. Binding was dependent upon time and temperature, and maximal binding was obtained by incubating the labelled hormone for 4-6 h at 24 degrees C. An increase in binding was noted between 7 and 12 days in culture. In cells cultured for 12 days, addition of unlabelled hGH, bGH or rGH caused a dose-dependent displacement of 125I-labelled hGH, whereas oPRL was ineffective. Scatchard analysis resulted in a linear plot, and the number of binding sites/cell was approximately 5700, with a dissociation constant of 0.46 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Proteoglycans from bovine fetal epiphyseal cartilage. Sedimentation velocity and light scattering studies of the effect of link protein on proteoglycan aggregate size and stability.

Proteoglycan monomer and link proteins were isolated from bovine fetal epiphyseal cartilage and characterized. The physical characteristics of proteoglycan monomer were: s0(20) = 21.3 S, D0t,z = 4.25 x 10(-8)cm2/sec, Mw = 3 x 10(6) and Rg,z = 980A. Link protein preparations contained link proteins 1 and 2, but little or none of the fragment, link protein 3. Link protein-stabilized and link protein-free proteoglycan aggregates were reassembled from proteoglycan monomer, link protein and hyaluronate. The effect of epiphyseal cartilage link protein on aggregate size and stability was examined in sedimentation velocity studies. Compared with link protein from mature bovine nasal and articular cartilages, which contain appreciable amounts of link protein 3, epiphyseal cartilage link protein dramatically stabilized aggregates at pH 5. In the presence of link protein, 92% of the proteoglycan monomers were bound as aggregate at pH 7, and 81% were bound at pH 5. In the absence of link protein, 51% of monomers were bound at pH 7, and only 32% were bound at pH 5. The progressive dissociation of link protein-free aggregates as a function of decreasing pH, and of increasing temperature, was also examined in dynamic light scattering studies. The results of the light scattering studies were in perfect accord with the results of the sedimentation velocity studies. However, compared with the sedimentation velocity studies, the dynamic light scattering studies provided a more detailed and informative description of the dissociation of the link-free aggregate as a function of pH, as a function of temperature, and of the capacity of link protein to stabilize aggregate against dissociation at decreased pH or elevated temperature.

Animals↗
PubMed1990

Aggregation of proteoglycans in cephalic, epiphyseal and articular cartilages in growing sheep.

The purpose of this study was to determine whether there are age and site related differences in proteoglycan aggregation in craniofacial and epiphyseal cartilages from neonatal and two-month-old lambs. Proteoglycans were extracted using a dissociative extraction method, and aggregates and monomers separated with molecular sieving. Only a small proportion of the proteoglycans were isolated as aggregates in the articular and mandibular condylar cartilage of the neonatal animals, while in the nasal septal, epiphyseal and synchondrosal cartilages of the same animals the portion of proteoglycans isolated as aggregates, was 3 to 6 times as high. During the first 2 months of postnatal development the proportion of proteoglycans isolated as aggregates tripled in the articular and mandibular condylar cartilages, it decreased substantially in the anterior and posterior nasal septum, while it decreased slightly in the other cartilages. These observations indicate that there are age and site related differences in the extent of proteoglycans isolated as aggregates in cephalic, epiphyseal and articular cartilages.

Aging↗
PubMed1999

Recessively inherited multiple epiphyseal dysplasia with normal stature, club foot, and double layered patella caused by a DTDST mutation.

We have observed over 25 different mutations in the diastrophic dysplasia sulphate transporter gene (DTDST) in association with the recessive disorders achondrogenesis 1B, atelosteogenesis 2, and diastrophic dysplasia. The c862t (R279W) transition is the most common mutation in non-Finnish patients, but in these disorders it is usually combined with other DTDST mutations. We had not seen a case of homozygosity for c862t (R279W) until we analysed DNA from a 36 year old male with tall-normal stature (180 cm) who asked for genetic counselling for suspected multiple epiphyseal dysplasia. He was treated for club foot and hip dysplasia at birth. Skeletal changes consistent with multiple epiphyseal dysplasia, with the peculiar finding of a double layered patella, were recognised during childhood. Cleft palate, swelling of the ear pinna, and hitch hiker thumb were absent. He was found to be homozygous, and both healthy parents heterozygous, for the R279W mutation in DTDST, and his fibroblasts showed a sulphate incorporation defect typical of DTDST disorders. Counselling was given for a recessive disorder, thereby considerably reducing the probability of affected offspring. Multiple epiphyseal dysplasia is more frequently caused by dominant mutations in the COMP (EDM1, McKusick 132400) and COL9A2 genes (EDM2, McKusick 600204). A few other patients and families with features similar to our proband have been described previously and considered to have autosomal recessive MED (EDM4, McKusick 226900). This observation confirms the existence of this entity and assigns it to the phenotypic spectrum associated with mutations at the DTDST locus.

Adult↗
PubMed1999

Cellular localization and expression of insulin-like growth factors (IGFs) and IGF binding proteins within the epiphyseal growth plate of the ovine fetus: possible functional implications.

The insulin-like growth factors (IGFs) are important in the regulation of normal fetal musculoskeletal growth and development, and their actions have been shown to be modulated by IGF binding proteins (IGFBPs). Because the anatomical distribution of IGFBPs is likely to dictate IGF bioavailability, we determined the cellular distribution and expression of IGF-I, IGF-II, and IGFBP-1 to IGFBP-6 in epiphyseal growth plates of the fetal sheep, using immunocytochemistry and in situ hybridization. Little mRNA for IGF-I was detectable within the growth plates, but mRNA for IGF-II was abundant in germinal and proliferative chondrocytes, although absent from some differentiating chondrocytes and hypertrophic cells. Immunohistochemistry for IGF-I and IGF-II showed a presence of both peptides in all chondrocyte zones, including hypertrophic cells. Immunoreactive IGFBP-2 to -5 were localized within the germinal and proliferative zones of chondrocytes, but little immunoreactivity was present within the columns of differentiating cells. IGFBP immunoreactivity again appeared in hypertrophic chondrocytes. IGFBP mRNA in chondrocytes of the epiphyseal growth plate was below the detectable limit of in situ hybridization. However, low levels of mRNAs for IGFBP-2 to -6 were detected by the reverse transcriptase polymerase chain reaction. A co-localization of IGFBPs with IGF peptides in intact cartilage suggests that they may regulate IGF bioavailability and action locally. To test this hypothesis, monolayer cultures of chondrocytes were established from the proliferative zone of the growth plate, and were found to release immunoreactive IGF-II and to express mRNAs encoding IGFBP-2 to -6. Exogenous IGFBP-3, -4, and -5 had an inhibitory action on IGF-II-dependent DNA synthesis. IGFBP-2 had a biphasic effect, potentiating IGF-II action at low concentrations but inhibiting DNA synthesis at equimolar or greater concentrations relative to IGF-II. Long R3 IGF-I, which has a reduced binding affinity for many IGFBPs, was more potent than native IGF-I in promoting DNA synthesis by chondrocytes. Our findings suggest that locally produced IGF-II and IGF-I derived from the circulation can influence fetal epiphyseal chondrogenesis, and that this may be modulated locally by multiple IGFBP expression.

Animals↗
PubMedDate not supplied

Primary subacute epiphyseal osteomyelitis: role of conservative treatment.

Primary subacute epiphyseal osteomyelitis is a rare disease. Owing to its insidious onset, mild symptoms, and inconsistent supportive laboratory data, diagnosis and treatment are usually delayed. The authors report a retrospective review of 16 patients with hematogenous osteomyelitis primarily affecting the epiphysis. In all of these patients an osteolytic lesion developed. In eight patients it was confined to the epiphysis or apophysis alone; in the other patients there was contiguous involvement of the adjacent metaphysis. Complete clinical and radiologic healing was observed in all patients after antibiotic therapy alone. Based on this experience, in view of the controversy in the literature, the authors recommend a conservative treatment policy in the management of both epiphyseal and epiphyseal-metaphyseal subacute osteomyelitis as the treatment of choice. Surgery should be reserved for persistent infection that does not respond to appropriate antibiotic therapy or when bone lesions cannot be distinguished from bone tumors by use of all available imaging modalities.

Anti-Bacterial Agents↗
PubMed1999

[Effect of transforming growth factor-beta on proliferation cycle of epiphyseal chondrocyte].

In order to investigate the effect of transforming growth factor-beta (TGF-beta) on chondrocyte proliferation cycle, we used flow-cytometry to assess the epiphyseal chondrocyte of embryonic chick femora which was cultured in free-serum media and treated with TGF-beta. The results showed that after treated with TGF-beta for 24 h, the proliferation indexes(PIs) of experimental groups(0.11 ng, 0.33 ng, 1.00 ng/ml) were lower than the PIs of the control groups, but the PI of 3.00 ng/ml group was higher than that of the control group (P < 0.001). After treated for 48 h, except the 0.11 ng/ml group, the PIs of experimental groups were lower than those of the control (P < 0.001). And after treated for 96 h, the PIs of all groups were higher than those of the control; the PI of the 0.33 ng/ml group was the highest (P < 0.001). These suggest that after treated in varied time and dosage, the effect of TGF-beta on epiphyseal chondrocyte is obvious, and TGF-beta on epiphyseal chondrocyte is obvious, and TGF-beta can inhibit chondrocyte proliferation first, and then its effect on chondrocyte can transform from inhibition into proliferation.

Animals↗
PubMed1992

Sports-related epiphyseal injuries of the lower extremity. An epidemiologic study.

Sports-related epiphyseal injuries in children and adolescents have been becoming more prevalent during recent years. We report 85 patients with epiphyseal fractures of the lower extremity treated in our hospital during the last twenty years, of which 60 were males and 25 females with an average age of 12.6 years (range 4 to 17 years of age). The injuries were sustained during soccer in 28% and during alpine skiing in 26% of the cases, of which the former was responsible for most of the injuries reported in males and the latter for those in females. The most frequently seen localizations were in the distal tibial epiphysis (31 cases), followed by the distal fibula (17) and the proximal tibial epiphysis (15). Of the reported 85 epiphyseal fractures 30 were Salter-Harris type I injuries, 25 type II, 8 type III and 11 were type IV fractures, while 11 were avulsion fractures. Of these patients, 56% were treated surgically, while conservative treatment was chosen for 44% of the patients. Of the 49 patients available for follow-up, complications were documented in 9 instances, including 3 leg length discrepancies, 4 axis deviations, one avascular necrosis of the femoral head and one case of osteomyelitis, of which 6 required corrective surgery.

Adolescent↗
PubMed2003

[Expression of bax protein in the cartilage cells of epiphyseal plate].

OBJECTIVE: This experiment was designed to investigate the expression of Bax in the chondrocytes of the epiphyseal plate cartilage. METHODS: Immunocytochemistry ABC method was used to determine the distribution of Bax immunoreactivity in the epiphyseal plate cartilage of rats. RESULTS: Bax immunoreactivity was non-uniformly distributed throughout the epiphyseal cartilage. There was no Bax expression in chondrocytes under the perichondrium. Bax expression was observed in the resting chondrocytes of epiphysis; it increased in the proliferative chondrocytes of epiphysis, and immunoreactivity was mainly in the cytoplasm of chondrocytes; Bax expression was maximal in the hypertrophic chondrocytes of epiphysis, and immunoreactivity was mainly in the cytoplasm and nuclei of chondrocytes. CONCLUSION: These immunocytochemical data indicate that Bax may promote chondrocytes apoptosis of epiphysis through an accumulative increase in quantity.

Animals↗
PubMed2004

Influence of doxycycline on the epiphyseal plate cartilage of the rats in experimental osteoarthrosis, induced by iodoacetate.

In 36 Wistar rats with the iodoacetate-induced experimental osteoarthrosis (OA), effects of doxycycline, given orally, were determined on histochemical reactions of glycosaminoglycans (GAG) in the epiphyseal plate cartilage. The epiphyseal plate of rats with OA was reduced in height (especially the proliferative zone), cell columns were disorganized, many chondrocytes were irregular and polygonal, their nuclei were pycnotic, the intensity of GAG staining was irregular and predominantly reduced, which can be interpreted as signs of degeneration. A concomitant administration of doxycycline in the second group of rats prevented, to some extent, the negative effects of iodoacetate on chondrocytes and led to a more pronounced intensity of GAG reactions in the matrix of the epiphyseal plate.

Animals↗
PubMed2005

Multiple epiphyseal dysplasia in children: beware of overtreatment!

PURPOSE: To determine the various musculoskeletal manifestations of multiple epiphyseal dysplasia in children, and the course of this disease in childhood. METHODS: Ten children were diagnosed and treated at the Children's Hospital of Eastern Ontario (CHEO) for multiple epiphyseal dysplasia, 1976-2001. We reviewed the clinical, pathological and radiographic records for these cases to determine cause of presentation and progress of the musculoskeletal pathology during the course of this disease in this age group. RESULTS: Average age at time of first presentation was 6 years and 4 months (range 2 wk to 13 yr). Mean follow-up was 6 years and 2 months (range 1-144 mo). Only 2 children required surgery. Two children were diagnosed at birth; 2 were referred as cases of bilateral Legg-Calvé-Perthes disease. Two children presented with asymmetrical genu valgum; 1 with knee pain, genu valgum, loose bodies, and early degenerative joint disease of both knees; and 2 with limp. CONCLUSION: Although multiple epiphyseal dysplasia is a disease of childhood, it is seldom severe enough to require operative intervention in the initial 2 decades of life.

Diagnosis, Differential↗
PubMed1992

[Intramedullary nailing osteosynthesis with epiphyseal fixation of fractures of the proximal humerus in adults. 1 to 3-year follow-up].

The authors used a medullary pinning with epiphyseal fixation in the treatment of superior metaphyseal fractures of the humerus for 41 patients aged 22 to 82 years. There were 28 cases with epiphyseal fractures and 12 with metaphyseal fractures. The follow-up was 1 to 3 years. The pins were introduced through the triceps brachii after perforation of the diaphysis, 1 cm above the ulnar fossa. Results were very good. Strength returned within 8.5 weeks. There was only one case of nonunion of a proximal diaphyseal fracture due to a technical fault (diastasis between fragments). Rehabilitation began immediately, resulting in good elbow motion in 35 cases. The shoulder motion was the same as the healthy side in 36 cases, and inferior to 90 degrees of abduction in only two complex epiphyseal fracture. The proximal humerus was never perforated by the pins. The authors find this new instrumentation to be very effective.

Adult↗
PubMed1990

Morphology of normal and osteochondrotic porcine articular-epiphyseal cartilage. A study in the domestic pig and minipig of wild hog ancestry.

Osteochondrosis is a generalized skeletal disorder that affects the growth cartilage in the growing domestic pig but not in the minipig of wild hog ancestry. In the present study, we compare the ultrastructure of the articular and epiphyseal growth cartilage in the domestic pig with that in the minipig. The domestic pigs had areas of enlarged epiphyseal cartilage with chondronecrosis, which had caused focal impairment of the endochondral ossification, with retention of cartilage in the subchondral bone. Areas of chondronecrosis close to blood vessels were found in the resting zone, with no evidence of thickened cartilage or impaired ossification. The chondronecrosis was surrounded by chondrocytes, organized in small clusters, containing many lipid droplets. The vascular channels adjacent to the chondronecrosis contained degenerated blood vessels. The minipigs showed no areas of enlarged epiphyseal cartilage. A few dead chondrocytes could be seen close to vascular channels which contained morphologically normal blood vessels. We conclude that restricted perivascular chondrolysis may occur in the pig without the presence of vascular degeneration and without progressing to osteochondrosis.

Animals↗
PubMed1989

[Treatment of macrodactyly with epiphyseal plate excision in growth retardation].

Macrodactyly, the overgrowth of one or more fingers or toes, is a comparatively rare congenital deformity. The enlargement includes skin, subcutaneous tissue, nerve, joint and bone. The bony involvement is usually limited to phalanges and the metacarpus is rarely involved. Since 1979, 10 cases have been seen in our hospital. Among them, there were 6 cases whose giant fingers or toes were treated with epiphyseal plates removing. The postoperative results (the longest follow-up period was 9 years) were satisfying. The growth of fingers or toes was completely stopped but in one case whose toes became longer because his epiphyseal plates were not removed thoroughly. According to the experiences of two cases, when the gigantism occurred in the thumb, the first metacarpus was also involved. The excision of epiphyseal plates was an effective method to halt further growth of macrodactyly for children and teenagers. And this method is simply and easily to be performed.

Adolescent↗
PubMed1987

Epiphyseal injuries of the foot and ankle.

A thorough knowledge of functional growth plate anatomy and physiology is essential to proper management of epiphyseal foot and ankle injuries. The ability to classify foot and ankle fractures according to the Salter-Harris anatomic and radiographic classification provides useful prognostic information that may affect treatment. The Dias-Tachdjian mechanistic classification system for pediatric ankle fractures provides useful information about the extent of osseous and soft tissue injury and the best method of closed reduction and correlates well with the Lauge-Hansen system, which is widely used for adult ankle fractures. Most epiphyseal foot fractures involve the metatarsals or phalanges and can usually be managed with closed reduction. Considerable spontaneous correction of deformity can be expected in the younger child (under age 10 years), but one should be aware that sagittal plane and rotational malalignment of the metatarsal heads may cause significant problems. Salter-Harris type I and II fractures of the ankle can usually be managed with closed reduction. Salter-Harris type III and IV ankle fractures with greater than 2 mm of displacement require open reduction and internal fixation. One must also have a high index of suspicion for juvenile Tillaux and triplane transitional fractures that may not be obvious on plain radiographs. Although these fractures usually do not produce significant limb-length discrepancies, they are intra-articular fractures and ankle joint arthritis can result. Finally, younger children (under age 10 years) have a better prognosis for spontaneous correction of nongrowth arrest-induced deformities but a much poorer prognosis with growth arrest injuries than do older children, in whom growth arrest does not usually cause a significant problem. All children with growth plate injuries should be followed at regular intervals for at least 2 years or to skeletal maturity in the case of physeal disturbance. Treatment of epiphyseal fractures of the foot and ankle must be individualized but should always be based upon a thorough knowledge of anatomy, bone growth physiology, classification, potential pitfalls, and prognosis.

Adolescent↗