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PubMed2001

Computer automated approach to the extraction of epiphyseal regions in hand radiographs.

Epiphyseal region is the most sensitive region to developmental changes of the skeletal system. Extraction of this area is the very first step in any computerized image analysis. In this report a fully automated analysis of a hand radiograph resulting in extraction of distal and middle regions of the II, III, and IV phalanx is presented. The processing is performed in 3 stages. First, the trend of background is removed from radiograph to obtain a binary hand mask. At this stage a labeling procedure is necessary to eliminate artifacts (markers). Then, II, III, and IV phalanges are identified in the binary image, and the phalangeal axes are drawn. Finally, the intensity profile along each phalangeal axis is analyzed, and, on its basis, distal and middle regions are located. The presented procedure is designed as a part of currently developed system for automatic bone age assessment; however, it also can be as a preprocessing step in other diseases the diagnoses of which may require a computer assistance.

Adolescent↗
PubMed1975

Studies on matrix vesicles isolated from chick epiphyseal cartilage. Association of pyrophosphatase and ATPase activities with alkaline phosphatase.

Fractions composed primarily of cells (Fraction I), membrane fragments (Fraction II) and matrix vesicles (Fraction III) were isolated from chick epiphyseal cartilage. The characteristics of the alkaline phosphatase (EC 3.1.3.1), pyrophosphatase (EC 3.6.1.1) and ATPase (EC 3.6.1.3) activities in the matrix vesicle fraction were studied in detail. Mg-2-+ was not absolutely essential to any of the activities, but at low levels was stimulatory in all cases. Higher concentrations inhibited both pyrophosphatase and ATPase activities. Both the stimulatory and inhibitory effects were pH-dependent. Ca-2-+ stimulated all activities weakly in the absence of Mg-2-+. However, when Mg-2-+ was present, Ca-2-+ was slightly inhibitory. Thus, none of the activities appear to have a requirement for Ca-2-+, and hence would not seem to be involved with active Ca-2-+ transport in the typical manner. The distribution of alkaline phosphatase, pyrophosphatase, and Mg-2-+ ATPase activities among the various cartilage fractions was identical, and concentrated primarily in the matrix vesicles. Conversely, the highest level of (Na-+ + K-+)-ATPase activity was found in the cell fraction. All activites showed nearly identical sensitivities to levamisole (4 - 10-3 M) which caused nearly complete inhibition of alkaline phosphatase and pyrophosphatase. About 10-15% of the ATPase activity was levamisole-insensitive. The data are consistent with the concept that the Mg-2-+-ATPase and pyrophosphatase activities of matrix vesicles stem from one enzyme, namely, alkaline phosphatase.

Adenosine Triphosphatases↗
PubMed1979

Enzymatic characterization of the chondrocytic alkaline phosphatase isolated from bovine fetal epiphyseal cartilage.

Purified chondrocytic alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) from bovine fetal epiphyseal cartilage hydrolyzes a variety of phosphate esters as well as ATP and inorganic pyrophosphate. Optimal activities for p-nitrophenyl phosphate, ATP and inorganic pyrophosphate are found at pH 10.5, 10.0 and 8.5, respectively. The latter two substrates exhibit substrate inhibition at high concentrations. p-Nitrophenyl phosphate demonstrates decreasing pH optima with decreasng substrate concentration. Heat inactivation studies indicate that both phosphorolytic and pyrophosphorolytic cleavage occur at the same site on the enzyme. Mg2+ (0.1-10.0 mM) and Mn2+ (0.01-0.1 mM) show a small stimulation of p-nitrophenyl phosphate-splitting activity at pH 10.5. Levamisole, Pi, CN-, Zn2+ and L-phenylalanine are all reversible inhibitors of the phosphomonoesterase activity. Pi is a competitive inhibitor with a Ki of 10.0 mM. Levamisole and Zn2+ are potent non-competitive inhibitors with inhibition constants of 0.05 and 0.04 mM, respectively. The chondrocytic alkaline phosphatase is inhibited irreversibly by Be2+, EDTA, EGTA, ethane-1-hydroxydiphosphonate, dichloromethane diphosphonate, L-cysteine, phenyl-methylsulfonyl fluoride, N-ethylmaleimide and iodoacetamide. NaCL, KCL and Na2SO4 at 0.5-1.0 M inhibit the enzyme. At pH 8.5, the cleavage of inorganic pyrophosphate (pyrophosphate phosphohydrolase, EC 3.6.1.1) by the chondrocytic enzyme is slightly enhanced by low levels of Mg2+ and depressed by concentrations higher than 1mM. Ca2+ show only inhibition. Similar effects of Mg2+ and Ca2+ on the associated ATPase (ATP phosphohydrolase, EC 3.1.6.3) activity were observed. Arrhenius studies using p-nitrophenyl phosphate and AMP as substrates have accounted for the ten-fold difference in V in terms of small differences in both the enthalpies and entropies of activation which are 700 cal/mol and 2.3 cal/degree per mol, respectively.

Adenosine Triphosphatases↗
PubMed1975

Lipid composition of isolated epiphyseal cartilage cells, membranes and matrix vesicles.

1. Intact cells, cell fragments (membranes) and matrix vesicles were isolated from the proliferating and calcifying layers of epiphyseal cartilage by sequential hyaluronidase and collagenase digestion and differential centrifugation. Lipids were extracted and analyzed for various lipid classes and their fatty acid composition by column, thin-layer, paper and gas-liquid chromatography. 2. On a protein basis the isolated matrix vesicles had more total lipid than either the membrane or cell fractions, the vesicles and membranes being richer in non-polar lipids and containing smaller quantities of phospholipids than whole cells. Expressed as a percentage of the total lipid, the cells were richer in triacylglycerols and lower in free fatty acids than in the membrane or vesicle fractions. The proportion of free cholesterol and the cholesterol/phospholipid ratio were nearly twice as high in the matrix vesicles as in the other tissue fractions. Choline and ethanolamine phosphoglycerides progressively declined in the membrane and matrix vesicle fractions, whereas serine phosphoglycerides and sphinogomyelin increased. Non-phosphorus-containing polar lipids were present in all fractions, the vesicles being richer in polyhexosyl ceramides, cerebrosides, glycosyldiacylglycerols and certain uncharacterized acidic polar lipids. 3. Fatty acid patterns of the matrix vesicles were distinctive from those of isolated cells, being generally richer in 18 : 0 and 18 : 2, and lower in 16 : 1 and 18 : 1 fatty acids. Monoacyl forms were similarly increased in 16 : 0 and/or 18 : 0, and reduced in 16 : 1, 18 : 1 or 20 : 2 fatty acids, depending on the lipid class. The fatty acid composition of diphosphatidylglycerol from cells and matrix vesicles was markedly different, providing evidence that the cardiolipin in the vesicles was not from mitochondrial components. 4. Based on the fact that the matrix vesicles were significantly enriched in free cholesterol, sphingomyelin, glycolipids and serine-phosphoglycerides, it is concluded that they are derived from the plasma membrane of the cell, supporting earlier conclusions based upon morphological and enzymological evidence.

Alkaline Phosphatase↗
PubMed1986

Epiphyseal-based designs for tibial plateau components--I. Stress analysis in the frontal plane.

Two-dimensional, finite element studies were conducted of the proximal tibia before and after joint arthroplasty. Equivalent-thickness models projected onto the mid-frontal plane were created for the natural, proximal tibia and for the proximal tibia with four different types of tibial plateau components. All components simulated bony ingrowth fixation, i.e. no cement layer existed between component and bone. In addition, the interface between component and bone was assumed to be intimately connected, representing complete bony ingrowth and a rigid state of fixation. Loads consisted of bi-condylar and uni-condylar forces. Results indicated that conventional plateau designs with central posts or multiple pegs led to higher stress magnitudes in the trabecular bone near the distal ends of the post/pegs and stress shielding at more proximal locations. A design without posts or pegs whose interface geometry mimics the epiphyseal plate minimizes bone stress shielding. An implant consisting of separate components covering each condyle was found effective in limiting component tilting and the consequent tensile stresses caused by non-symmetrical, uni-condylar loading.

Epiphyses↗
PubMed1990

Characterization of cytosolic glucocorticoid receptor of fetal rat epiphyseal chondrocytes.

The cytosolic glucocorticoid receptor of 21st gestational day rat epiphyseal chondrocytes has been evaluated. The receptor, a single class of glucocorticoid binding component approached saturation, utilizing [3H]triamcinolone acetonide ([3H]TA) as the radiolabeled ligand, at approximately 1.8-2.0 x 10(-8) M. The dissociation constant (Kd) reflected high-affinity binding, equaling 4.0 +/- 1.43 x 10(-9) M (n = 7) for [3H]TA. The concentration of receptor estimated from Scatchard analysis was approximately 250 fmol/mg cytosolic protein and when calculated on a sites/cell basis equalled 5800 sites/cell. The relative binding affinities of steroid for receptor were found to be triamcinolone acetonide greater than corticosterone greater than hydrocortisone greater than progesterone greater than medroxyprogesterone acetate much greater than 17 alpha-hydroxyprogesterone much greater than testosterone greater than 17 beta-estradiol. Cytosolic preparations activated in vitro by warming (25 degrees C for 20 min) were shown to exhibit an increased affinity for DNA-cellulose. 46% of the total specifically bound activated ligand-receptor complex was bound to DNA-cellulose. Cytosol maintained at 0-4 degrees C in the presence of 10 mM molybdate or activated in vitro in the presence of molybdate, bound to DNA-cellulose at 8 and 10% respectively. DEAE-Sephadex elution profiles of the nonactivated receptor were indicative of a single binding moiety which eluted from the columns at 0.4 M KCl. Elution profiles of activated receptor were suggestive of an activation induced receptor lability. The 0.4 M KCl peak was diminished, while a concomitant increase in the 0.2 M KCl peak was only modestly discernible. Evaluation of endogenous proteolytic activity in chondrocyte cytosol using [methyl-14C]casein as substrate show a temperature-dependent proteolytic activity with a pH optimum of 5.9-6.65. The proteolytic activity was susceptible to heat inactivation and was inhibitable, by 20 mM EDTA. The sedimentation coefficient of the nonactivated receptor was 9.3s (n = 6) on sucrose density gradients and exhibited steroid specificity and a resistance to activation induced molecular alterations when incubated in the presence of 10 mM molybdate. Receptor activation in vitro, in the absence of molybdate induced an increased receptor susceptibility to proteolytic attack and/or enhanced ligand receptor dissociation as evidenced by a diminution of the 9.3s binding form without a concomitant increase in 5s or 3s receptor fragments.

Animals↗
PubMed1988

Free vascularised epiphyseal transplantation in upper extremity reconstruction.

We describe preliminary observations on the use of free vascularised transfer of proximal fibular epiphysis in replacement of proximal humeral epiphysis or distal radial epiphysis in three patients. An analysis of the early results shows evidence of longitudinal growth, graft hypertrophy and epiphyseal adaptation in transplanted epiphysis. A review of the problems in this type of surgery is included.

Arm↗
PubMed1975

Proteoglycans of mineralizing rib and epiphyseal cartilage.

Rib cartilage from growing guinea pigs and epiphyseal cartilage from Beagle puppies were separated into three fractions, representing non-mineralized, low mineralized, and high mineralized, tissue, by centrifuging finely ground material in acetone/bromoform density gradients. Following extraction under dissociative conditions, the proteoglycans were fractionated by density gradient ultracentrifugation under associative and dissociative conditions. With the onset of mineralization, the cartilage lost approximately half its content of proteoglycans. The proteoglycans remaining in the calcified cartilage differed in composition and in size from those of nonmineralized tissue. With the increased mineral content of the tissues the ratios of protein to polysaccharide, of chondroitin sulfate to keratan sulfate, and of 4-sulfate to 6-sulfated chondroitin sulfate increased in the proteoglycan fraction. Furthermore, gel chromatograms indicated decreased proportions of very high molecular weight proteoglycans, in mineralized tissue.

Animals↗
PubMed1986

Isolation and characterization of a metalloprotease associated with chicken epiphyseal cartilage matrix vesicles.

A metalloprotease has been isolated from matrix vesicles of chicken epiphyseal cartilage and subsequently characterized. Matrix vesicles obtained by collagenase digestion and differential centrifugation were further purified by Sepharose CL2B gel filtration. The protease was solubilized from the vesicles by treatment with deoxycholate and freeze-thawing, and then isolated by Sephadex G150 gel filtration. Disc electrophoresis of the enzyme, which displayed protease activity toward azocasein substrate, gave a single protein band. Based on molecular weight (MW) determination, lack of immunocross reactivity, and differences in electrophoretic migration, there is little possibility of any contamination with external protease from the commercial collagenase used for vesicle preparation. The matrix vesicle protease had a MW of 33,000 and a pH optimum of 7.2 and was completely inhibited by 0.1 mM EDTA and 0.2 mM o-phenanthroline. alpha 2-Macroglobulin, ovalbumin, cysteine, penicillamine, ethane-1-hydroxy-1, 1-diphosphonate (EHDP) and pyrophosphate at higher concentrations were also inhibitory. The inhibition by omicron-phenanthroline was reversed by Co2+, Zn2+, Fe2+, and Cu2+. Protease activity was most abundant in the heavy fraction of matrix vesicles fractionated by discontinuous sucrose density gradient centrifugation. Release of this protease at the calcifying front could degrade noncollagenous protein moieties that inhibit precipitation of minerals in the extravesicular matrix and thus facilitate mineralization.

Animals↗
PubMed2003

Epiphyseal osteoblastoma of tibia with xanthomatous stromal reaction.

Osteoblastoma occurring in long bones has a distinctive predilection for the metaphysis and the diaphysis. Epiphyseal location is rare. Although variation in histologic patterns is a well-known feature of this tumor, xanthomatous stromal reaction has not yet been described. We report a case of a 34-year-old man who developed an osteoblastoma primarily located in the epiphysis of his left tibia with extension into the metaphysis. The striking histologic features included a prominent xanthoma-like stroma consisting of foamy histiocytes in addition to focal areas with classical configuration of an osteoblastoma. The significance of this finding is discussed.

Adult↗
PubMed2005

Expression and intracellular localization of Pyk2 in normal and v-src transformed chicken epiphyseal chondrocytes.

The expression and localization of prolin-rich tyrosine kinase 2 (Pyk2) were studied in chick embryo epiphyseal chondrocytes. Two immunoreactive bands were detected in chondrocytes, a major band with an apparent Mr of 123 kDa and a minor band with an apparent Mr of 68 kDa. The major band appears to migrate as a doublet with apparent Mr of 116/123 kDa. Increased levels of the three forms of Pyk2 were observed in v-src transformed chondrocytes as compared to control uninfected chondrocytes. Immunofluorescent staining shows that Pyk2 is clearly visible in the cytosol and in the perinuclear region of control and v-src-chondrocytes and displays a pattern very similar to the distribution of the mitochondrial marker Mito Tracker. More, immunofluorescent staining shows that Pyk2 is nuclear in most chondrocytes. By subcellular fractionation, the p116/123 Pyk2 doublet, was found to be accumulated mainly in the cytoplasm while the p68 Pyk2 form, was found to be accumulated exclusively in the nucleus. The differential nuclear/cytoplasmic distribution of the Pyk2 forms remains unchanged after v-Src-induced transformation. The p68 Pyk2 form could no longer be detected by using a N-terminus domain-specific anti-Pyk2 antibody. Consistently, Pyk2 immunoreactivity was restricted to the cytoplasm of control and v-src transformed chondrocytes. Thus it appears that the p68 Pyk2 form that accumulates in the nucleus has a deletion in the N-terminus region.

Animals↗
PubMed2004

Fundamental limits on longitudinal bone growth: growth plate senescence and epiphyseal fusion.

Longitudinal bone growth occurs rapidly in early life but then slows and, eventually, ceases. The decline in growth rate is caused primarily by a decrease in the rate of chondrocyte proliferation and is accompanied by structural changes in growth plate cartilage. This programmed senescence does not appear to be caused by hormonal or other systemic mechanisms but is intrinsic to the growth plate itself. In particular, recent evidence indicates that senescence might occur because stem-like cells in the resting zone have a finite proliferative capacity, which is exhausted gradually. In some mammals, including humans, proliferative exhaustion is followed by epiphyseal fusion, an abrupt event in which the growth plate cartilage is replaced completely by bone.

Aging↗
PubMed1979

A critical re-evaluation of the anisotropic index used in polarization microscopy: a study on epiphyseal cartilage.

Topo-optical reactions specific for collagen and glycosaminoglycans were performed on epiphyseal cartilage plates which differed in age, in chemical composition, and in structure. Retardation values were measured with the polarization microscope and anisotropic index values were calculated after each reaction. It was found that the anisotropic index proposed earlier for quantitative evaluation of topo-optical reactions did not refer either to the submicroscopic orientation pattern or to the quantity of cartilage matrix components. It is suggested that retardation values of induced birefringence may be only used to characterize the spatial orientation of these components in the cartilage matrix.

Aging↗
PubMed2001

Native and DPPA cross-linked collagen sponges seeded with fetal bovine epiphyseal chondrocytes used for cartilage tissue engineering.

Collagen-based biomaterials in the form of sponges (bovine type I collagen, both native and cross-linked by treatment with diphenylphosphorylazide, noted control and DPPA sponges respectively) were tested as three-dimensional scaffolds to support chondrocyte proliferation with maintenance of the phenotype in order to form neocartilage. Control and DPPA sponges were initially seeded with 10(6) or 10(7) foetal bovine epiphyseal chondrocytes and maintained for 4 weeks in culture under static conditions in RPMI/NCTC medium with 10% FCS and without addition of fresh ascorbic acid. Both supports were always present during the study and a partial decrease in size and weight was detected only with control sponges, both seeded and unseeded. Cell proliferation was only noted in the 10(6) cells-seeded sponges (4-fold increase after 4 weeks of culture). Specific cartilage collagens (types II and XI) were deposited in the matrix throughout the culture and traces of type I collagen were noticed only in the culture medium after 2-3 weeks and 4 weeks in the case of 10(6) and 10(7) cells-seeded sponges, respectively. Glycosaminoglycans accumulated in the matrix, up to 1.8 and 9.8% of total dry weight after one month with both seeding conditions, which was much lower than in the natural tissue. In the 10(7) cells-seeded sponges, mineral deposition, observed with unseeded sponges, was significantly decreased (2- to 3-fold). These in vitro results indicate that both collagen matrices can support the development of tissue engineered cartilage.

Amino Acids↗
PubMed2003

Altered expression of integrins in RSV-transformed chick epiphyseal chondrocytes.

Chondrocytes have been shown to express both in vivo and in vitro a number of integrins of the beta1-, beta3- and beta5-subfamilies (Biorheology 37 (2000) 109). Normal and v-Src-transformed chick epiphyseal chondrocytes (CEC) display different adhesion properties. While normal CEC with time in culture tends to increase their adhesion to the substrate by organizing focal adhesions and actin stress fibers, v-Src-transformed chondrocytes display a refractile morphology and disorganization of actin cytoskeleton. We wondered whether the reduced adhesion and spreading of v-Src-transformed chondrocytes could be ascribed to changes in integrin expression and/or function. Integrin expression by normal CEC is studied and compared to v-Src-transformed chick chondrocytes, using monoclonal and polyclonal antibodies to integrins alpha- and beta-chains. We show the presence of alpha1-, alpha3-, alphav-, alpha6-, beta1- and beta3-chains on CEC, with very low levels of alpha2- and alpha5-chains. Alphav chain associates with multiple beta subunits in normal and transformed chondrocytes. With the exception of alpha1- and alpha2-chains, the levels of the integrin chains analyzed are higher in transformed chondrocytes as compared with normal chondrocytes. In spite of the increased levels of integrin expression, transformed chondrocytes exhibit loss of focal adhesion and actin stress fibers and low adhesion activity on several extracellular matrix constituents. These observations raise the possibility that, in addition to its effects on global pattern of integrin expression, v-Src can influence integrin function in chondrocytes.

Actin Cytoskeleton↗
PubMed1988

[Infection of the tendon sheath following an open epiphyseal fracture. Apropos of a case].

Injuries of the distal phalanx of the digits in children may lead to various lesions. The association of avulsion of the nail with an epiphyseal separation is not uncommon. This is in fact an open fracture, with the risk of infection of the flexor digitorum tendon sheath. The authors report such an observation and discuss the mechanism and treatment.

Bacterial Infections↗