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PubMed2006

Lower degree of mineralization found in cortical bone of adolescent idiopathic scoliosis (AIS).

UNLABELLED: A lowered bone mineral density (BMD) was observed in trabecular bone in a significant number of AIS patients. The present study aims at investigating whether lower BMD is a systemic phenomenon, which would also be present in the cortical component of long bone. SUBJECTS AND METHODS: 78 AIS girls (age:15-18y.o) with either moderate (Cobb: 20-40) or severe (Cobb: >40) curve and 44 age-matched controls were recruited. The BMD of the distal region and the mid-shaft of radius were measured with a multi-layer peripheral quantitative computed tomography (pQCT). The trabecular bone and cortical bone BMD and the morphology of mid-shaft were compared. RESULTS: Both trabecular and cortical BMD in severe AIS group was significantly lower than the control by 8.7% and 1.7% (p<0.05 for both), respectively. However, the cortical bone area of the mid-shaft did not show any differences from the normal control subjects. DISCUSSION: This study demonstrates a systemic low BMD including the cortical bone. It is suggested that AIS girls may have disturbance in mineralization and ossification during peripubertal growth.

Adolescent↗
PubMed1982

Proteoglycans and calcification of cartilage in the femoral head epiphysis of the immature rat.

The femoral heads of young rats have been used to monitor changes in proteoglycan structure during growth and endochondral ossification. Proteoglycans were extracted in good yield. The tissue content of proteoglycans increased until the time of calcification and then decreased. In contrast, the collagen content increased over the period studied. On Day 20, just preceding the onset of calcification, the proteoglycans had a lower glycosaminoglycan content, were somewhat smaller, and contained a larger proportion of molecules that were not capable of interacting with hyaluronic acid. On Day 25, during ongoing calcification, the proportion of proteoglycans that were not capable of interacting with hyaluronic acid was low, while it again was high on Day 40, just preceding ossification. The relative glycosaminoglycan content of the proteoglycans was somewhat lower on Day 20 and Day 40. The results indicate that both at the time of calcification and at the time of ossification the proteoglycan structure changes, perhaps indicating a functional role for the proteoglycans in the calcification process.

Animals↗
PubMed2005

Cartilage formation in growth plate and arteries: from physiology to pathology.

Vascular calcifications are the consequence of several pathological conditions such as atherosclerosis, diabetes, hypercholesterolemia and chronic renal insufficiency. They are associated with risks of amputation, ischemic heart disease, stroke and increased mortality. A growing body of evidence indicates that vascular smooth muscle cells (VSMCs) undergo chondrogenic commitment eventually leading to vascular calcification, by mechanisms similar to those governing ossification in the cartilage growth plate. Our knowledge of the formation of cartilage growth plate can therefore help us to understand why and how arteries calcify and, consequently, develop new therapeutic strategies. Reciprocally, thorough consideration of the events leading to ectopic chondrocyte differentiation appears crucial to further increase our understanding of growth plate formation. In this context, we will review the effects of known or suspected factors that promote chondrogenic differentiation in growth plate and arteries.

Animals↗
PubMed1986

Teratologic evaluation of dermally applied diethylene glycol monomethyl ether in rabbits.

Diethylene glycol monomethyl ether (DEGME) was applied to the skin of pregnant rabbits on Days 6 through 18 of gestation in order to assess the fetotoxic and teratogenic potential by the dermal route. Rabbits were treated with 0, 50, 250, or 750 mg/kg/day of DEGME, and fetuses were examined for external, visceral, and skeletal alterations. Topical application of the highest dose, 750 mg/kg/day, produced slight embryotoxicity, fetotoxicity, and toxicity in the maternal animal. Maternal effects were characterized by decreased weight gain and a concurrent physiologic decrease in red blood cells and packed cell volume values. In addition, a slight increase in embryonic resorptions was observed. The fetal alterations observed, mild forelimb flexure, slight-to-moderate dilation of the renal pelvis, retrocaval ureter, cervical spurs, and delayed ossification of the skull and sternebral bones, are considered to be indicative of fetotoxicity but not teratogenicity. Slight fetotoxicity in the form of delayed ossification of the skull and cervical spurs was seen in the 250 mg/kg/day dose group. No adverse maternal, embryonic, or fetal effects were observed at 50 mg/kg/day.

Administration, Topical↗
PubMed1996

Failure of ventral body wall closure in mouse embryos lacking a procollagen C-proteinase encoded by Bmp1, a mammalian gene related to Drosophila tolloid.

The mouse bone morphogenetic protein1 (Bmp1) gene encodes a secreted astacin metalloprotease that cleaves the COOH-propeptide of procollagen I, II and III. BMP-1 is also related to the product of the Drosophila patterning gene, tolloid (tld), which enhances the activity of the TGFbeta-related growth factor Decapentaplegic and promotes development of the dorsalmost amnioserosa. We have disrupted the mouse Bmp1 gene by deleting DNA sequences encoding the active site of the astacin-like protease domain common to all splice variants. Homozygous mutant embryos appear to have a normal skeleton, apart from reduced ossification of certain skull bones. However, they have a persistent herniation of the gut in the umbilical region and do not survive beyond birth. Analysis of the amnion of homozygous mutant embryos reveals the absence of the fold that normally tightly encloses the physiological hernia of the gut. At the electron microscopic level, the extracellular matrix of the amnion contains collagen fibrils with an abnormal morphology, consistent with the incorporation of partially processed procollagen molecules. Metabolical labelling and immunofluorescence studies also reveal abnormal processing and deposition of procollagen by homozygous mutant fibroblasts in culture.

Amnion↗
PubMed2006

Morphology of the lateral pterygoid muscle associated to the mandibular condyle in the human prenatal stage.

The lateral pterygoid muscle (LPM) inserts at the condyle and the articular disc and plays a central role in mandibular movement via the Temporomandibular Articular Complex. The aim of this study was to examine the association between the morphology of LPM muscular fascicles and the degree of mineralization of the mandibular condyle in the prenatal stage employing structural, ultrastructural and microanalytical evaluation. Sixteen human fetuses at 11-37 weeks of gestation, with no apparent pathology and resulting from spontaneous abortions, were included in the study. Samples from lateral pterygoid muscle and the mandibular condyle were processed for light microscopy and electron microscopy and microanalysis. Desmin immunolabeling (dilution 1: 25 Dako) and alpha sarcomeric actin immunolabeling (dilution 1:50 Dako) employing the avidin-biotin system were used in paraffin embedded samples. Contralateral samples were examine by transmission electron microscopy. Four condyles (at 17-21 weeks of gestation) were used to measure the relative content of calcium and phosphorous employing the X-ray diffraction microanalytical technique. At 11-16 weeks of gestation, the LPM was composed of secondary myotubes associated to satellite cells and nerve fibers. At 18 weeks, the muscle exhibited multiple compact fascicles and the condyle showed a thin, external, subperiostal mineralized layer with few central bone spicules. At 20 weeks, at the site of insertion of the LPM, the bone trabeculae of the condyle contained an electrondense matrix with abundant mineralization nuclei. At 17-21 weeks of gestation no significant variations in the contents of phosphorous and calcium were observed. At 24 weeks, transmission electron calcium and microscopy studies revealed a marked increase in the functional units of the muscle fascicles. Also, at this age muscle fibers exhibited differences in the expression of desmin and alpha sarcomeric actin. At 37 weeks the muscle became multipennate in appearance, exhibiting a more complex organization than younger fetuses. Alpha sarcomeric actin labeling became light with age. This results suggest that between 16 and 22 weeks of gestation the differentiation and maturation process of the muscle fibers precedes and prevails over the development and mineralization process from mandibular condyle. The rudimentary performance of the prenatal LPM would be one of the factors that regulate the process of ossification at the level of the mandibular condyle. The rate of ossification would increase starting from 22 of gestation week.

Actins↗
PubMed1985

Occurrence and formation of vertebral anomalies in hatchery reared ayu, Plecoglossu altivelis.

The influence of low food supply on the time and order of formation of vertebral column and the occurrences of vertebral anomalies in hatchery-reared ayu, Plecoglossus altivelis, were described and reported. The larvae reared with low food supply, "lack of living micro-crustaceans," grew considerably more slowly than the well fed larvae. The order of cartilaginification and ossification of the vertebral column seemed unaffected by growth rate, but time of formation varied according to the growth rate. The frequencies of abnormal cartilaginous arch and spine, abnormal arch and spine, compressed (shortened) vertebrae and fused vertebrae in fish reared with low food supply were clearly higher than those for fish with high food supply. The slow space of cartilaginification and ossification of vertebral column and the high incidence of vertebral anomalies may be associated with lack of living micro-crustaceans during the larval stage.

Animal Nutritional Physiological Phenomena↗
PubMed1989

Answer please. Blount's disease: tibia vara.

Infantile tibia vara, although uncommon compared to normal physiologic bowing, is significant due to the resultant progressive deformities if not diagnosed early. The key radiographic finding is medial tibial metaphyseal beaking and fragmentation. Although the etiology is unclear, it appears to be an acquired growth disturbance of the proximal medial tibial epiphysis, ossification center, and metaphysis rather than any type of avascular necrosis. The Langenskiöld six-stage classification is useful for the diagnostic, prognostic, and treatment staging of the disease. The adolescent form is less common and less severe with only slight irregular thickening of the physis present on radiograph. The MDA appears to be the most reproducible method for measuring angular deformities in both variants of the disease. Treatment of the infantile stages I or II consists of observation and bracing. Stage III or IV disease in children over age 3 years with more than 5 degrees of varus angulation should be treated with corrective valgus osteotomy. Stages V or VI may require repeated surgical treatment with multiple osteotomies and possible contralateral epiphysiodesis. The adolescent form frequently requires surgery when there is significant physical impairment related to the severe genu varum.

Child↗
PubMed2006

[CCN family genes in the development and differentiation of cartilage tissues].

CCN family is a novel family of proteins consisting of several modulator molecules. The members display a variety of physiological and pathological functions ; hence they are currently attracting the interest of a number of biologists. In terms of the development and regeneration of cartilage tissues, CCN2/connective tissue growth factor (CTGF) is best known among the CCN family members, since it efficiently promotes endochondral ossification and articular cartilage regeneration. Recently, it has been uncovered how CCN2 gene expression is duly regulated along with the differentiation of chondrocytes, which is uncovering the genetic program leading to cartilage tissue development. Moerover, production of other members, such as CCN1 and CCN4, are occasionally observed in chondrocytes, suggesting the contribution of the entire CCN family members to the developmental process of cartilage in vivo.

Animals↗
PubMed1998

Hydroxyapatite orbital implant. A light- and electron-microscopic and immunohistochemical study.

OBJECTIVE: This study aimed to characterize the constituents of the ingrown host tissue in explanted orbital coral spheres by means of light electron microscopy and immunohistochemistry and to compare findings at different intervals after implantation. DESIGN AND METHODS: A microscopic retrospective laboratory study of three explanted coral spheres from three different patients was undertaken. The first specimen was an infected hydroxyapatite orbital implant, which was removed after 18.5 months and processed for standard light microscopy and transmission electron microscopy. Immunohistochemistry was performed using vimentin, actin, CD-68, and CD-34 marker. Two other explanted spheres (after 3 weeks and 2.5 months) were examined by light microscopy only, because no fibrovascular ingrowth could be detected. RESULTS: On light microscopy, the pores of the first coral were filled entirely with the fibrovascular tissue. A basophilic line reminiscent of calcium deposition was seen along hydroxyapatite spicules, where it often was associated with newly formed bony lamellae. Similar lines were seen partially in the 2.5-month specimen but not in the 3-week specimen. Immunohistochemistry of the first specimen enhanced visualization of the capillary network when the CD-34 marker was used. The fibrovascular tissue was uniformly vimentin-positive and partially actin-positive. On transmission electron microscopy, typical fibroblasts and myofibroblasts were observed. The latter were separated by thin sheets of banded collagen and formed pseudoepithelial structures. Proliferating vessels often showed high endothelial cells. CONCLUSIONS: The fibrovascular ingrowth contains not only vimentin-positive regular fibroblasts but also actin-positive myofibroblasts. Interaction between the invading tissue and hydroxyapatite structures leads to long-term ossification.

Actins↗
PubMed1995

Marrow development and its relationship to bone formation in vivo: a histological study using an implantable titanium device in rabbits.

During embryogenesis, the creation of marrow sinusoids is intimately related to the coupled processes of osteogenesis and osteoclastic resorption. We set out to further define the relationship between bone formation and marrow development by implanting an intraosseous titanium device into the tibiae of rabbits which permits the examination of bone formation under standardized and reproducible conditions as well as allowing repeated sampling of new bone. A hollow channel is incorporated into the device into which tissue can grow. The device was left in place for 6 weeks to allow osseous integration to occur, after which the initial rod of new tissue growth was removed and subsequent histological and immunohistological sequence of events observed over the next 7 weeks. Interpretation of its morphological changes was further aided by concurrent histomorphometric studies. Because the channel was in direct continuity with the marrow cavity and isolated from the endosteum, immediate marrow regeneration was expected, following dissolution of the blood clot. Instead, our studies indicated that hemopoietic marrow cells, including the erythroid and myeloid series as well as megakaryocytes, did not appear until 3 weeks after implantation of the chamber when the newly formed bone had been remodeled to form an expanded marrow cavity. This intraosseous device is a useful in vivo model for studying the development of bone marrow hemopoietic and nonhemopoietic stromal cells and our results confirm the previous observation that influx of marrow cellular elements follow the formation of bone during endochondral as well as intramembranous ossification.

Animals↗
PubMed2002

Bone spurs: mechanism of production of different shapes based on observations in Dupuytren's diathesis.

Bone spur formation on the shaft of the middle phalanx of the little finger was an incidental finding during surgical treatment of five cases of Dupuytren's contracture. The presence of such spurs in Dupuytren's contracture is not adequately explained in the literature. In areas of high tensile stress, such as the attachments of fascia and fibrous cords, bone remodels to reduce stress concentration and to make the stress transfer from one tissue to the other as smooth as possible. It cannot be regarded as the same process that is seen in heterotopic calcification in other sites in the body, and should be regarded instead as a physiological bone response to tensile stresses rather than a change intimately coupled with Dupuytren's disease.

Adult↗
PubMed1999

Matrix GLA protein is a developmental regulator of chondrocyte mineralization and, when constitutively expressed, blocks endochondral and intramembranous ossification in the limb.

Matrix GLA protein (MGP), a gamma-carboxyglutamic acid (GLA)-rich, vitamin K-dependent and apatite-binding protein, is a regulator of hypertrophic cartilage mineralization during development. However, MGP is produced by both hypertrophic and immature chondrocytes, suggesting that MGP's role in mineralization is cell stage-dependent, and that MGP may have other roles in immature cells. It is also unclear whether MGP regulates the quantity of mineral or mineral nature and quality as well. To address these issues, we determined the effects of manipulations of MGP synthesis and expression in (a) immature and hypertrophic chondrocyte cultures and (b) the chick limb bud in vivo. The two chondrocyte cultures displayed comparable levels of MGP gene expression. Yet, treatment with warfarin, a gamma-carboxylase inhibitor and vitamin K antagonist, triggered mineralization in hypertrophic but not immature cultures. Warfarin effects on mineralization were highly selective, were accompanied by no appreciable changes in MGP expression, alkaline phosphatase activity, or cell number, and were counteracted by vitamin K cotreatment. Scanning electron microscopy, x-ray microanalysis, and Fourier-transform infrared spectroscopy revealed that mineral forming in control and warfarin-treated hypertrophic cell cultures was similar and represented stoichiometric apatite. Virally driven MGP overexpression in cultured chondrocytes greatly decreased mineralization. Surprisingly, MGP overexpression in the developing limb not only inhibited cartilage mineralization, but also delayed chondrocyte maturation and blocked endochondral ossification and formation of a diaphyseal intramembranous bone collar. The results show that MGP is a powerful but developmentally regulated inhibitor of cartilage mineralization, controls mineral quantity but not type, and appears to have a previously unsuspected role in regulating chondrocyte maturation and ossification processes.

1-Carboxyglutamic Acid↗
PubMed1989

Regulation of matrix vesicle metabolism by vitamin D metabolites.

Matrix vesicles are membrane organelles found in the extracellular matrix of calcifying cells. Vitamin D-responsive alkaline phosphatase specific activity has been localized to matrix vesicles in chondrocyte and osteoblast cultures. The effect of hormone is both metabolite and cell specific. Alkaline phosphatase in matrix vesicles produced by resting zone chondrocytes is stimulated by 24,25(OH)2D3 whereas alkaline phosphatase in matrix vesicles produced by growth zone chondrocytes is responsive to 1,25(OH)2D3. However, mesenchymal cell cultures, which exhibit a chondrogenic phenotype when exposed to bone inductive proteins in vitro, produce vesicles with alkaline phosphatase activity that is unaffected by either 1,25(OH)2D3 or 24,25(OH)2D3. Incorporation and release of arachidonic acid into phosphatidylethanolamine is also differentially regulated by 1,25(OH)2D3 and 24,25(OH)2D3 in chondrocytes. These data suggest that vitamin D metabolites may regulate endochondral ossification by altering matrix vesicle enzyme activities, perhaps through changes in membrane phospholipid metabolism.

Alkaline Phosphatase↗
PubMed2005

GPI-specific phospholipase D (GPI-PLD) is expressed during mouse development and is localized to the extracellular matrix of the developing mouse skeleton.

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is abundant in serum and has a well-characterized biochemistry; however, its physiological role is completely unknown. Previous investigations into GPI-PLD have focused on the adult animal or on in vitro systems and a putative role in development has been neither proposed nor investigated. We describe the first evidence of GPI-PLD expression during mouse embryonic ossification. GPI-PLD expression was detected predominantly at sites of skeletal development, increasing during the course of gestation. GPI-PLD was observed during both intramembraneous and endochondral ossification and localized predominantly to the extracellular matrix of chondrocytes and to primary trabeculae of the skeleton. In addition, the mouse chondrocyte cell line ATDC5 expressed GPI-PLD after experimental induction of differentiation. These results implicate GPI-PLD in the process of bone formation during mouse embryogenesis.

Animals↗
PubMed2002

The PTH/PTHrP receptor can delay chondrocyte hypertrophy in vivo without activating phospholipase C.

One G protein-coupled receptor (GPCR) can activate more than one G protein, but the physiologic importance of such activation has not been demonstrated in vivo. We have generated mice expressing exclusively a mutant form of the PTH/PTHrP receptor (DSEL) that activates adenylyl cyclase normally but not phospholipase C (PLC). DSEL mutant mice exhibit abnormalities in embryonic endochondral bone development, including delayed ossification and increased chondrocyte proliferation. Analysis of the differentiation of embryonic metatarsals in vitro shows that PTH(1-34) and forskolin inhibit, whereas active phorbol ester stimulates, hypertrophic differentiation. Thus, PLC signaling via the PTH/PTHrP receptor normally slows the proliferation and hastens the differentiation of chondrocytes, actions that oppose the dominant effects of PTH/PTHrP receptors and that involve cAMP-dependent signaling pathways.

Animals↗