The role of heparin in angiogenesis

A series of experiments is described in which: (i) mast cells were found to accumulate at a tumour site before the ingrowth of new capillaries; (ii) heparin released by mast cells increased the migration of capillary endothelial cells in vitro; and (iii) heparin enhanced tumour angiogenesis in vivo. These experiments led to the discovery that protamine and platelet factor 4 are angiogenesis inhibitors. This finding suggests a central role for heparin or related glycosaminoglycans in the growth regulation of capillary blood vessels.

Common structures of the core proteins of interstitial proteoglycans

Connective tissues, with few exceptions, contain easily distinguishable large and small proteoglycans with chondroitin sulphate or dermatan sulphate side-chains. One group consists of the large aggregating proteoglycans that have the capacity to interact specifically with hyaluronate, thereby forming very large aggregates. These proteoglycans can be divided into two families which can be separated by electrophoresis. Preliminary results indicate that one of these may be derived from the other by processing in the extracellular matrix. Although most prominent in cartilage, similar proteoglycans are present in many types of tissue, such as aorta, sclera and tendon. Another population are the large non-aggregating proteoglycans, identified in cartilage. These proteoglycans show structural features partially different from any of the others. They may represent a distinct population of molecules present in many connective tissues. Many tissues contain major populations of small, non-aggregating proteoglycans. These can be divided into two major groups, differing in the composition of their core proteins, while having similar types of side-chain constituents. One group is represented by proteoglycans from nasal cartilage and aorta, while the other is represented by proteoglycans from tendon, bone, sclera and cornea.

Fluorometric determination of DNA in cartilage of various species

A sensitive, modified 3,5-diaminobenzoic acid (DABA), fluorometric DNA assay was developed and compared to mithramycin and ethidium bromide assays in determining the DNA content of dense connective tissues including: Swarm rat chondrosarcoma, rabbit, dog, monkey, and most importantly, adult human articular cartilage. In the more cellular cartilages, the three methods gave equivalent results. However, in the relatively acellular human cartilage, the DABA method was shown to be superior. Both the mithramycin and ethidium bromide gave falsely high values compared to the DABA method, which by subtraction after DNase digestion approached the DABA value. The latter was completely DNase sensitive. With the DABA method, the DNA content of human cartilage can be obtained on less than 5 mg wet weight of fresh, alcohol-fixed, or lyophilized material. While the DNA can also be released by digestion with papain or protease from Streptomyces griseus, proteinase K was preferable. The comparison of literature values for other fluorometric and spectrophotometric assays of human cartilage suggest these methods overestimate human articular cartilage DNA concentrations, whereas the DABA values were in line with those predicted from previous morphometric analysis. Thus, the modified method represents an improvement in DNA analysis of dense connective tissues.

Cartilage proteoglycan-induced arthritis in BALB/c mice. Antibodies that recognize human and mouse cartilage proteoglycan and can cause depletion of cartilage proteoglycan with little or no synovitis

Human fetal cartilage proteoglycan (PG) induces the development of an erosive polyarthritis and spondylitis in BALB/c mice. We have examined the properties of 3 monoclonal antibodies (MAb) to human fetal cartilage PG isolated from immunized mice that cross-react with mouse cartilage PG. Compared with sera from arthritic mice, which contain antibodies reactive with keratan sulfate, MAb 202 (IgG1) reacted only with a protein-related epitope that is distributed on both hyaluronic acid-binding and chondroitin sulfate-attachment regions. MAb 813 (IgG1) reacted with the same fragments and recognized an epitope with the immunologic characteristics of keratan sulfate. MAb 945 (IgM) remains to be further characterized. Introduction of hybridomas secreting MAb 202 and MAb 945 into irradiated mice resulted in the loss of PG from articular cartilage and from growth plate cartilage (with MAb 202 only), as revealed by a loss of staining with toluidine blue. There was no synovial hyperplasia with MAb 202, but some hyperplasia and mononuclear cell infiltration was seen with MAb 945. This was accompanied by the binding of immunoglobulins to articular cartilage, as demonstrated by immunofluorescence. The hybridoma secreting MAb 813 produced no cartilage changes or synovitis, and there was no immunoglobulin binding to cartilage. Polymorphonuclear leukocyte infiltration was never observed with these antibodies. These studies indicate that MAb reactive with mouse cartilage PG can cause the depletion of PG from hyaline cartilage by mechanisms that may be both complement dependent and complement independent. Antibodies may serve to release and expose PG antigen to immune cells, as well as causing a loss of the mechanical properties of cartilage that are PG dependent.

Two linkage-region fragments isolated from skeletal keratan sulphate contain a sulphated N-acetylglucosamine residue

Peptido-keratan sulphate fragments were isolated from the nucleus pulposus of bovine intervertebral discs (6-year-old animals) after chondroitin ABC lyase digestion followed by digestion of A1D1 proteoglycans by diphenylcarbamoyl chloride-treated trypsin and gel-permeation chromatography on Sepharose CL-6B. Treatment of these peptido-keratan sulphate fragments with alkaline NaB3H4 yielded keratan sulphate chains with [3H]galactosaminitol end-labels, and these chains were further purified by gel-permeation chromatography on Sephadex G-50 and ion-exchange chromatography on a Pharmacia Mono-Q column in order to exclude any contamination with O-linked oligosaccharides. The chains were then treated with keratanase, and the digest was chromatographed on a Bio-Gel P-4 column followed by anion-exchange chromatography on a Nucleosil 5 SB column. Two oligosaccharides, each representing 18% of the recovered radiolabel, were examined by 500 MHz 1H-n.m.r. spectroscopy, and shown to have the following structures: [formula: see text] The structure of oligosaccharide (I) confirms the N-acetylneuraminylgalactose substitution at position 3 of N-acetylgalactosamine in the keratan sulphate-protein linkage region found by Hopwood & Robinson [(1974) Biochem. J. 141, 57-69] but additionally shows the presence of a 6-sulphated N-acetylglucosamine. Electron micro-probe analysis specifically confirmed the presence of sulphur in this sample. This sulphate ester group differentiates the keratan sulphate linkage region from similar structures derived from O-linked oligosaccharides [Lohmander, De Luca, Nilsson, Hascall, Caputo, Kimura & Heinegård (1980) J. Biol. Chem. 255, 6084-6091].

An 18-kDa glycoprotein from bovine nasal cartilage. Isolation and primary structure of small, cartilage-derived glycoprotein

A glycosylated protein (small, cartilage-derived glycoprotein, SCGP) of approximately 18 kDa with unknown function has been isolated from dissociative extracts of bovine nasal cartilage and its primary structure determined. The protein has 121 amino acids, giving a calculated protein molecular weight of 13,878, four disulfide bonds, two N-linked oligosaccharides and one O-linked oligosaccharide. In nasal cartilage, this glycoprotein is in molar concentrations equivalent to 1/5-1/2 that of the link protein of cartilage proteoglycan aggregates, and it has also been isolated from bovine articular cartilage and from bovine fetal epiphysis. The N-terminal, glycosylated region of the molecule is relatively rich in arginine, proline, glycine, and threonine. The C-terminal 82 amino acids (which contains all four of the disulfide bonds and none of the carbohydrate) can be found as a discrete entity in cartilage extracts, indicating that the N-terminal domain is readily removed by extracellular proteolytic attack.

Identification of an inhibitor of neovascularization from cartilage

Certain tissues such as cartilage are resistant to vascular invasion, yet no single tissue-derived molecule that can inhibit angiogenesis has been reported. A protein derived from cartilage was purified that inhibits angiogenesis in vivo and capillary endothelial cell proliferation and migration in vitro in three separate bioassays. This protein is also an inhibitor of mammalian collagenase. These findings may help elucidate the mechanisms by which neovascularization is controlled in both normal and pathological states.

Micromechanical spectroscopy of cartilage proteoglycans: hydration

Proteoglycan subunits extracted from calf cartilage have been studied with a high resolving power mechanical spectroscopy: the Thermostimulated Creep (TSC). The influence of hydration on TSC spectra shows the existence of two types of bound water: the weakly bound water increases the inertia of proteoglycan and stiffens their structure; the strongly bound water is responsible to a compensation law indicating the existence of a resonance phenomenon at the physiological temperature. Because of the looseness of bonds in weakly bound water, an increase of the local pressure may induce, in vivo, a release of water in tissues. This hypothesis explains perfectly the role of a water pump of proteoglycans in cartilage.

The amino terminal sequence of the developmentally regulated Ch21 protein shows homology with amino terminal sequences of low molecular weight proteins binding hydrophobic molecules

Ch21 protein, a developmentally regulated chick embryo protein of 21,000 apparent molecular weight, was purified from culture medium of hypertrophic chondrocytes. The purification method included a DEAE cellulose chromatography column, a CM cellulose chromatography column and a HPLC molecular sieve column. The amino acid sequence of the amino terminal end of the protein was determined. Computer assisted analysis showed significant homology between this sequence and the amino terminal sequences of proteins that belong to the superfamily of the low molecular weight binding proteins sharing a basic framework for the binding and transport of small hydrophobic molecules. Determination of the amino terminal sequence of the chicken retinol binding protein excluded identity between this protein and the Ch21.

Concentration of ciprofloxacin in bone tissue after single parenteral administration to patients older than 70 years

The concentrations of ciprofloxacin produced in bone, cartilage and menisci after a single administration of 200 mg were determined at different intervals in a group of patients with an average age of 80 years. Concentrations of 0.11 to 0.94 mg/kg bone tissue were measured after 0.5 to 5 hours. In the cartilage a concentration of active substance was measureable only once (4.18 mg/kg). In the presence of marked circulatory disorders the active substance concentrations reached in the bone were above those found in the seriously damaged muscle. Although the concentrations reached in the bone are effective, no risk should be taken in osteomyelitis. Ciprofloxacin should therefore be used at high dosage and possibly be combined with another substance. Given for therapeutic purposes, a single dose of ciprofloxacin is naturally not effective enough, and given for prophylactic purposes, not safe enough to prevent a post-traumatic osteitis.

Glial fibrillary acidic protein immunoreactivity of chondrocytes in immature and mature teratomas

The immunoreactivity of chondrocytes for glial fibrillary acidic protein (GFAP), other intermediate filament proteins and S-100 protein was studied in formalin-fixed paraffin-embedded sections. A total of 95 cartilage specimens were examined from five immature teratomas, 12 mature teratomas, and a teratocarcinoma. GFAP-immunoreactive chondrocytes were abundant in immature cartilages, and as the cartilages maturated, these chondrocytes decreased and became distributed peripherally. Elastic cartilage had more GFAP-immunoreactive chondrocytes than non-elastic cartilage. GFAP-immunoreactive cartilage was often located close to central nervous tissue. Immunostaining for vimentin and S-100 protein revealed extensive distribution of immunoreactive chondrocytes in immature and mature cartilages, but in mature cartilage, chondrocytes at the center had less vimentin immunoreactivity. GFAP-immunoreactive chondrocytes also showed apparent immunostaining for vimentin. There was no difference in immunohistochemical staining for the alpha and beta subunits of S-100 protein. The immunoreactivities of teratoma cartilage specimens were quite similar to those of respiratory tract cartilage.

Occurrence in chick embryo vitreous humor of a type IX collagen proteoglycan with an extraordinarily large chondroitin sulfate chain and short alpha 1 polypeptide

We have prepared a high buoyant density proteoglycan fraction from the vitreous humor of 13-day-old chick embryos. Using immunoblot analysis coupled with chondroitinase digestion, we demonstrate that the purified preparation is composed predominantly of type IX collagen-like chondroitin sulfate proteoglycan with an alpha 1(IX) chain Mr approximately 23,000 shorter than the known alpha 1 in cartilage type IX. Also different from cartilage type IX is the size of the chondroitin sulfate chain attached to the alpha 2(IX) polypeptide; its Mr is approximately 350,000 indicating that it is approximately 10 times larger in vitreous humor than in cartilage. Examination of vitreous bodies at different developmental stages indicates that a transition occurs in the size of alpha 1(IX) in a well defined temporal pattern; at about stage 31, a cartilage-type alpha 1(IX) of Mr 84,000 is the predominant species, whereas at stage 36 and thereafter, a Mr 61,000 species appears with a concomitant disappearance of the Mr 84,000 species. Immunostaining for type IX collagen followed by electron microscopic observation of 13-day-old chick embryo vitreous humor reveals a regular D-periodic arrangement of vitreous type IX collagen proteoglycan along thin fibrils. It seems possible that the chondroitin sulfate chains of extraordinarily high viscosity and high molecular weight may extend away from the fibrils, thus contributing to structural as well as functional properties of this unique matrix.

An immunohistochemical study of localization of type I and type II collagens in mandibular condylar cartilage compared with tibial growth plate

Immunohistochemical localization of type I and type II collagens was examined in the rat mandibular condylar cartilage (as the secondary cartilage) and compared with that in the tibial growth plate (as the primary cartilage) using plastic embedded tissues. In the condylar cartilage, type I collagen was present not only in the extracellular matrix (ECM) of the fibrous, proliferative, and transitional cell layers, but also in the ECM of the maturative and hypertrophic cell layers. Type II collagen was present in the ECM of the maturative and hypertrophic cell layers. In the growth plate, type II collagen was present in the ECM of whole cartilaginous layers; type I collagen was not present in the cartilage but in the perichondrium and the bone matrices. These results indicate that differences exist in the components of the ECM between the primary and secondary cartilages. It is suggested that these two tissues differ in the developmental processes and/or in the reactions to their own local functional needs.

In situ cross-linking of cartilage proteoglycans

Although the in vitro interactions between purified cartilage matrix components have been studied extensively, little is known about these interactions in situ. In this study, cartilage was treated with a cross-linking reagent with a span of 1.2 nm between its reactive terminal groups in order to preserve the native relationships between closely associated matrix components throughout extraction, purification, and preparation for electron microscopy. After in situ cross-linking, electron microscopy and gel chromatography revealed that about one-half of the guanidine hydrochloride extractable proteoglycans were polymeric, usually with two to five proteoglycan subunits in each polymer. Cross-linking consistently involved the thin segments of the proteoglycan subunits. Some of the proteoglycan polymers were capable of binding hyaluronic acid and were parts of aggregates under associative conditions. SDS-polyacrylamide gel electrophoresis revealed that link proteins were present within the polymers, and studies in which purified proteoglycans were cross-linked in vitro confirmed that the link proteins increased the proportion of polymeric proteoglycans. These findings suggest that individual proteoglycans within cartilage have intimate associations with other proteoglycans that are mediated by link proteins.

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.

Identification of monoclonal antibodies that recognize novel epitopes in native chondroitin/dermatan sulfate glycosaminoglycan chains: their use in mapping functionally distinct domains of human skin

Five monoclonal antibodies (MAb), 7D4, 4C3, 6C3, 4D3, and 3C5, were produced in mice immunized with high buoyant density embryonic chick bone marrow proteoglycans (PGs) as antigen. All of these MAb recognized epitopes in native chick bone marrow and cartilage PGs which could be selectively removed by chondroitinase ABC and chondroitinase AC II, indicating that their epitopes were present in chondroitin sulfate glycosaminoglycans (GAGs). These MAb recognized epitopes present in purified cartilage PGs obtained from a wide variety of different vertebrate species. However, none of the new MAb detected epitopes in Swarm rat chondrosarcoma PG. On the basis of these results, we propose that these MAb recognize novel epitopes located in chondroitin sulfate/dermatan sulfate glycosaminoglycan (CS/DS GAG) chains, representing at least four and possibly five different structures. Immunocytochemical studies have shown that the epitopes identified by these new MAb are differentially distributed in tissues. All of these MAb immunocytochemically detected epitopes in embryonic chick cartilage and bone marrow. Three of them (4C3, 7D4, and 6C3) recognized epitopes in adult human skin. All three detected epitopes in the epidermis, one (6C3) strongly detected epitopes in the papillary dermis, and two (4C3, 7D4) detected epitopes in the reticular dermis. Immunostaining patterns in skin using the new MAb directed against native CS/DS structures were distinctly different from those obtained using MAb against the common CS isomers. The distribution of these CS epitopes in functionally distinct domains of different tissues implies that these structures have functional and biological significance.

[Structural characteristics of collagens from the skin and rib cartilage of patients with Ehlers-Danlos syndrome type II]

Collagens were analyzed in skin and rib cartilage of 9 patients with Ehlers-Danlos syndrome of the II type. Electrophoresis and CNBr-peptide mapping showed that extended inserts and deletions as well as rough impairments of post-translation processing were not detected in collagens of the I, II and III types from these patients. In the patients with Ehlers-Danlos syndrome of the II type distinct increase was observed both in the total ratio of collagens III/I (P = 0.95) and in the ratio of intact collagens III/I free of cross-links. A decrease in content of dimers beta 11 and beta 12 was found in two patients. The data obtained suggest that the Ehlers-Danlos syndrome of the II type involved deteriorations in the structure of collagens I responsible for decrease in stability and sometimes for impairments in cross-link formation. Increase in content of collagen II fraction, predisposed to proteolytic hydrolysis of terminal sites, as well as elevated sensitivity of collagen II to pepsin hydrolysis were found in collagens of rib cartilage from patients with the syndrome and with funnel chest deformation. This suggests the lowered stability of collagen II from rib cartilage in funnel chest deformation.

Inhibition of sulphate incorporation by chondrocytes in intact cartilage by hyaluronate from foetal cartilage

A number of regulators are available in cartilage to effect the local control of matrix production by chondrocytes. A cartilage slice assay has been used in this study to investigate the influence of such regulators (extracted from foetal cartilage) on intact cartilage. A net inhibition of sulphation was found, rather than stimulation as reported for extracts rich in the somatomedin-like, cartilage derived factor (CDF). Inhibition was due, to a high molecular weight component identified as hyaluronic acid (based on enzyme sensitivity, chromatographic behaviour and temperature stability). Its inhibition of sulphation in intact cartilage was more profound than that produced by commercially available umbilical cord hyaluronate. We conclude that foetal cartilage hyaluronate is a far more potent inhibitor of sulphation than hyaluronate from other sources, suppressing sulphation even in the presence of a somatomedin-like activator and in intact cartilage, which responds poorly to commercial hyaluronate.

Isolation and analysis of ribonucleic acids from skeletal tissues

We report a method for the isolation of total cellular RNA from mineralized or cartilaginous tissues. The procedure accommodates the large amount of hydroxyapatite and high buoyant density proteoglycans present in skeletal tissue samples, as well as the low cell density characteristic of these tissues. The procedure can be reliably used for processing a large number of small (100-800 mg) tissue samples. Tissues are homogenized in guanidine hydrochloride solution, then centrifuged at low speed, and filtered to remove the nonsolubilized extracellular matrix proteins. Subsequent high speed density gradient centrifugation produces a high yield of RNA (0.2-0.6 micrograms RNA/mg tissue) which is precipitated in a low pH sodium acetate solution. RNA extracted by this method has been analyzed for the expression of various genes by Northern blotting. In addition to mRNAs of bone- and cartilage-specific proteins, messenger RNA for growth factors, proto-oncogenes, and heat shock proteins can be detected.

[Changes in the structure of type I collagen and cross-links between type I and type III collagen chains in a patient with funnel chest]

Skin and rib cartilage collagens were studied in patient 1.I.K. with isolated form of pigeon chest as well as in a group of children without any impairments of connective tissue. Distinct decrease in stability of collagen I, an increase in the ration of alpha 1 (I)/alpha 2(I) chains and impairment in formation of beta 12 dimers were detected in the patient with pigeon chest. In the patient skin total ratio between collagens I and III, calculated from a content of BrCN-peptides, was similar to normal level, whereas the proportion was markedly increased between intact molecules of collagens III and I free of cross-links, which was calculated from the ratio of alpha 1(III)/alpha 2(I) chains. Presence of cross-links between alpha 1 (III) and alpha 2 (I) chains as well as between alpha 1 (III) and alpha 2 (I) chains was detected after peptide mapping of polypeptides arranged in the region of beta 11 and beta 12 dimers. All the collagen I preparation, extracted from skin of the patient 1.I.K., contained molecules with unstabilized N-terminal sites. These results suggest that mutation occurred in the N-terminal region of alpha 1(I) chain. Analysis of collagen from the patient 1.I.K. rib cartilage demonstrated a slight decrease in total stability of collagen II as well as elevated concentration of collagen II molecules containing unstabilized N-terminals. Mechanisms responsible for formation of cross-links between polypeptide chains of collagens I and III detected in human skin are discussed.

Induction of cells with a chondrocyte-like phenotype by treatment with 1 alpha,25-dihydroxyvitamin D3 in a human salivary acinar cell line

A clonal cell with an acinar cell phenotype, which was induced by 5-azacytidine treatment of a neoplastic human salivary intercalated duct cell line, was cultivated in the presence of 1 alpha,25-dihydroxyvitamin D3. Morphological changes occurred; large cells that were polygonal or round in shape and had numerous vacuoles in their cytoplasm appeared in the treated cells, whereas the same concentration of 1 alpha,25-dihydroxyvitamin D3 did not affect the morphology of the parental cells. Major alterations, such as expression of type II collagen, alpha and beta chains of S-100 protein, and sulfated proteoglycans, were observed in these cells with a phenotype similar to chondrocytes. After the removal of 1 alpha,25-dihydroxyvitamin D3 from the culture, the treated cells returned rapidly to the phenotype of the untreated cells. These findings indicate that the reversible differentiation into chondrocyte-like cells of a human salivary acinar cell line occurs in growth medium containing 1 alpha,25-dihydroxyvitamin D3.

Synthesis and secretion of Ch 21 protein in embryonic chick skeletal tissues

We reported the identification, purification and characterization of a low molecular weight protein (Ch 21) expressed in vitro by differentiating chondrocytes at a late stage of development and observed in vivo in the growth plate region of the long bones at the border between hypertrophic cartilage and newly formed bone (Descalzi Cancedda, F., P. Manduca, C. Tacchetti, P. Fossa, R. Quarto, R. Cancedda, J. Cell Biol. 107, 2455-2463 (1988]. In this article, the synthesis and location of Ch 21 protein in the chick embryo tibia at late stage of development were further investigated. Ch 21 was observed in the cartilage matrix surrounding marrow cavities and in the prearticular outer layer by immunolocalization. In addition, the timing of Ch 21 appearance during the tibia development and its distribution in the growth plate region was better defined. We first observed presence of Ch 21 in the perichondral mid-diaphyseal sleeve of 7-day-old tibia. Ch 21 antibodies stained also the newly formed bone. Synthesis and secretion in the culture medium of Ch 21 protein was observed when bone fragments or cultured osteoblasts isolated from 19-day-old embryo tibiae were labeled in vitro. A search for the presence of Ch 21 in the chick embryo sternum was performed. The synthesis of Ch 21, both in the presumptive calcification cranial portion and in the permanent cartilaginous caudal portion of the sternum, was shown by metabolic labeling of tissue slices.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of nonarticular cartilage, as demonstrated by release of a cartilage-specific protein, in rheumatoid arthritis

Analysis of human cartilage extracts by radioimmunoassay showed that the noncollagenous 148-kd cartilage matrix protein was present in extracts of tracheal cartilage but was undetectable in normal or arthritic joint cartilage, corroborating previous results with bovine cartilage samples. Concentrations of the protein in the circulation, as studied by radioimmunoassay, were greatly elevated in patients with rheumatoid arthritis and polyarticular juvenile rheumatoid arthritis. In contrast, patients with reactive arthritis and oligoarticular juvenile rheumatoid arthritis, as well as rheumatoid arthritis patients treated with low-dose glucocorticoids, had levels similar to those in healthy controls. The serum concentrations were not related to age. A patient with polychondritis and tracheal involvement had a high serum concentration of the protein, which decreased during plasma exchange and cyclophosphamide treatment. Studies of the release of this cartilage matrix protein, which is present in nonarticular cartilage but not in articular cartilage, should aid in the understanding of the mechanisms of cartilage involvement in disease, and the protein may become a clinically useful marker.

Quantitative criteria for evaluating the early development of osteoarthritis and the effect of diclofenac sodium

In assessing the possible efficacy of drugs for the treatment of osteoarthritis (OA), it may be helpful to have a model, in animals, of the early development of the disease prior to the expression of secondary phenomena. It is also necessary that such effects are quantifiable. To this end, the natural development of OA in the STR/ORT mouse has been investigated. It has been shown that very early events in the development of the disease are disturbances in the activity of chondrocytic glucose 6-phosphate dehydrogenase, the initial step in the pentose-phosphate pathway, and in the orientation of the proteoglycans of the matrix of the articular cartilage. The study has been done by reference to the effect of diclofenac sodium, which previously has been reported to retard the destruction of articular cartilage. The results appear to indicate that these markers may provide quantitative measures for assessing potential therapeutic agents.

Bartter's syndrome and chondrocalcinosis: a possible role for hypomagnesemia in the deposition of calcium pyrophosphate dihydrate (CPPD) crystals

A new case of association between Bartter's syndrome and chondrocalcinosis is reported. The patient was shown to have marked hypomagnesemia. Indomethacin and magnesium therapy was started and resulted in increased magnesemia, even if it did not reach normal levels. There was complete remission of articular symptoms and no progression on the radiological picture after 2 years of continuous magnesium and indomethacin therapy. The 7 available family members were studied to assess the possible presence of a familial form of chondrocalcinosis and/or hypomagnesemia. The literature is reviewed and reports of previously described associations between Bartter's syndrome and chondrocalcinosis are summarized. The possible role of hypomagnesemia in predisposing to deposition of calcium pyrophosphate dihydrate crystal in cartilagine is also discussed.

Macro and micro rate zonal analytical centrifugation of polydisperse and slowly diffusing sedimenting systems in isovolumetric density gradients. Application to cartilage proteoglycans

A method to study the polydispersity of zonally sedimenting and slowly diffusing macromolecules or particles in isokinetic or isovolumetric density gradients is presented. First, a brief theory is given for predicting the zonal profile after a "triangular" (or "inverse") zone is centrifuged. This type of zone is essential to preserve hydrodynamic stability of the very slowly diffusing polydisperse solutes. It is proven, both by semitheoretical considerations and by computer calculations, that the resulting concentration profile of macrosolute is almost identical with that obtainable with a rectangular zone coextensive with the triangular one and carrying the same total mass. Next, practical procedures are described for the convectionless layering of very small triangular zones (50 microL or less). The linearity and stability of the zones are experimentally tested and verified. Finally, the method is applied to cartilage proteoglycan preparations that included either the monomeric molecules only or both the monomeric and the aggregated ones. The zonal results are compared with those obtained by using conventional boundary sedimentation. The two sets of results are seen to coincide fairly well, thus proving that the present technique can add to preparative zonal centrifugation the analytical precision of boundary sedimentation. A multimodal polydisperse system is suggested to describe the aggregated proteoglycan macromolecules.

Keratan sulphate: a functional substitute for chondroitin sulphate in O2 deficient tissues?

Keratan sulphate and chondroitin sulphate can each fill space and exert swelling pressure in collagenous fibrillar matrices, but whereas the former is synthesised from glucose precursor without consuming NAD, the latter converts 2 mols of NAD for each uronate residue in the polymer chain. We suggest that the observed distribution of keratan sulphate and chondroitin sulphate in cartilage, cornea and intervertebral disc are determined by the ambient oxygen tension, and that keratan sulphate is preferentially synthesised in conditions of oxygen lack. The implications of this hypothesis in the physiology of contact lenses, cartilage degeneration, corneal scar repair and ageing are discussed.

Prophylactic treatment of canine osteoarthritis with glycosaminoglycan polysulfuric acid ester

The prophylactic effect of glycosaminoglycan polysulfuric acid ester (GAGPS) on cartilage lesions was studied using the Pond-Nuki model of canine osteoarthritis. Starting 2 days after anterior cruciate transection, GAGPS or saline was administered intraarticularly twice weekly for 4 weeks. After 4 weeks, gross and histologic medial femoral condylar lesions had developed to a lesser degree in GAGPS-treated dogs than in saline-treated dogs. The uronic acid and hydroxyproline levels in cartilage were significantly higher in the GAGPS-treated dogs than in the saline-treated dogs. Levels of active and latent collagenase in the cartilage of GAGPS-treated dogs were lower than in the cartilage of saline-treated dogs. With GAGPS treatment, swelling of the cartilage, an indicator of collagen network integrity, remained near control levels. Although increased synthesis of proteoglycan and collagen may account for some of these results, we propose that one mechanism of action of GAGPS is its ability to decrease collagen degradation, either by decreasing the synthesis of collagenase or by directly inhibiting the production of collagenase in cartilage.

Cartilage-specific 5' end of chick alpha 2(I) collagen mRNAs

Chondrocytes grown in suspension contain both type I and type II collagen mRNAs, yet synthesize only type II collagen. The inability of chondrocytes to synthesize the alpha 2 subunit of type I collagen, alpha 2(I), results from a severely reduced translation elongation rate (Bennett, V.D., and Adams, S.L. (1987) J. Biol. Chem. 262, 14806-14814). Furthermore, the alpha 2(I) collagen mRNAs from chondrocytes are translated inefficiently in vitro and appear slightly smaller than those from other cells (Focht, R.J., and Adams, S.L. (1984) Mol. Cell. Biol. 4, 1843-1852). These observations suggest that the reduced translation elongation rate may be due to an intrinsic property of the mRNAs. In this report we demonstrate that the alpha 2(I) collagen mRNAs from suspended chondrocytes are 120 bases shorter than those from other cells, and that the first 94 bases of the chondrocyte mRNAs differ from the corresponding region of the calvaria mRNAs. The unique 5' end of the chondrocyte alpha 2(I) collagen mRNAs accounts for their smaller size and may be responsible for the translation elongation defect. Interestingly, the alpha 2(I) collagen mRNAs from chondrocytes grown in monolayer, rather than in suspension, no longer display the cartilage-specific 5' end, suggesting that cell shape and/or adhesion may modulate the structure of the 5' end of the chondrocyte alpha 2(I) collagen mRNAs.

Application of the ferrocyanide-reduced osmium method for mineralizing cartilage: further evidence for the enhancement of intracellular glycogen and visualization of matrix components

The ferrocyanide-reduced osmium (FRO) fixation method was applied to neonatal mouse mandibular condylar cartilage for its processing for electron microscopy. The results were compared to those obtained by the conventional glutaraldehyde-osmium tetroxide fixation method. Three different stages in the life cycle of condylar cartilage cells were examined. FRO enabled the visualization of delicate fibrillar mesh in the matrix of all three zones of the cartilage, resulting in a dense appearance of the intercellular matrix. The classical stellate shape of matric granules seen in cartilage fixed with glutaraldehyde-osmium tetroxide was not observed in FRO-processed tissues. Chondrocytes that were FRO-processed almost entirely filled their lacunar space. In their pericellular area, fibrillar material and electron-dense aggregates could be demonstrated by the FRO method. As a conclusion of this study, it is recommended to supplement a conventional protocol with the FRO fixation method for routine and research purposes.

[Determination of the amino acid composition of cartilage and creatine phosphokinase isoenzymes with the use of phenylthiocarbamyl amino acid derivatives]

A method for estimation of amino acid composition and collagen-specific amino acids was developed. The assay was based on the precolumn reaction of amino acids with phenylisothiocyanate. The phenylthiocarbamyl derivatives were analyzed by means of reverse-phase chromatography on octadecyl sorbents, which involved gradient elution with ethanol and sodium or ammonium acetate. The method was used for effective separation of collagen-specific and main amino acids in cartilage hydrolysate from healthy persons and of patients with funnel chest and Ehlers-Danlos syndrome and also for determination of amino acid composition in creatine phosphokinase B- and M-subunits.

Positivity to glial fibrillary acidic protein in bone, cartilage, and chordoma

Twenty vertebral bones, 11 costal, 11 epiglottic, six tracheal, and five bronchial cartilages and seven chordomas were evaluated by the application of peroxidase-antiperoxidase (PAP) indirect immunohistochemical method for localization of glial fibrillary acidic protein (GFAP). Positive immunostaining for GFAP was observed in osteocytes of normal bone (13/20), chondrocytes of normal epiglottis (5/11), costal cartilage (3/11), trachea (2/6), and bronchus (4/5). Four of seven chordomas had neoplastic cells that exhibited cytoplasmic positivity to GFAP. These findings suggested that osteocytes, chondrocytes, and chordoma cells have cytoskeletal intermediate filaments that are antigenically identical to or similar to or associated with GFAP.

Quantitative analysis of collagen expression in embryonic chick chondrocytes having different developmental fates

A quantitative determination of collagen expression was carried out in cultured chondrocytes obtained from a tissue that undergoes endochondral bone replacement (ventral vertebra) and one that does not (caudal sterna). The "short chain" collagen, type X is only expressed in the former while the other "short chain" collagen type IX, was primarily expressed in the latter. These two tissues also differ in that vertebral chondrocytes express moderate levels of both type I procollagen mRNAs which were translated into full length procollagen chains both in vivo and in vitro, while caudal sternal chondrocytes did not. The percent of collagen synthesis was about 50% in both cell types, but sternal cells expressed twice as much collagen as vertebral cells even though type II procollagen was more efficiently processed to alpha-chains in vertebral chondrocytes than in sternal chondrocytes. The number of type II procollagen mRNA molecules/cell was found to be about 2300 in vertebral chondrocytes and about 8000 in sternal cells, in good agreement with the results reported by Kravis and Upholt (Kravis, D., and Upholt, W. B. (1985) Dev. Biol. 108, 164-172). There were about 630 copies of type I procollagen mRNAs with an alpha 1/alpha 2 ratio of 1.6 in vertebral chondrocytes compared with 5100 copies and an alpha 1/alpha 2 ratio of 2.2 in osteoblasts, and less than 40 copies in sternal cells. Since the rate of type I collagen chain synthesis was 50 times greater in osteoblasts than in vertebral cells, type I procollagen mRNAs were about six times less efficiently translated in vertebral cells than in osteoblasts. The type I mRNAs in vertebral chondrocytes were polyadenylated and had 5' ends that were identical in osteoblasts, fibroblasts, and myoblasts. Moreover, type I mRNAs isolated from vertebral chondrocytes were translated into full length preprocollagen chains in vitro in rabbit reticulocyte lysates. Thus, chondrocytes isolated from cartilage tissues with different developmental fates differed quantitatively and qualitatively in total collagen synthesis, procollagen processing, and distribution of collagen types.

[Molecular heterogeneity of proteoglycan aggregates of human hyalin cartilage in normal conditions and in systemic bone dysplasia]

Components of proteoglycan aggregates of human hyalin cartilage were studied under conditions of normal state and in some forms of osteochondrodysplasia. Extraction of uronic acids and protein from the tissue, amount of fractions and electrophoretic mobility of proteoglycan monomers, rations protein/glycosaminoglycans, keratan sulfate/chondroitin sulfate, a level and type of sulfatation as well as molecular mass of chondroitin sulfate, amino acid composition of rod protein, heterogeneity of binding proteins (concerning their isoelectric points and molecular masses) and immunoreactivity of protein moiety in proteoglycan aggregates were studied in rib cartilage, knee joint and ala ossis ilii. Structural parameters of proteoglycan aggregates proved to be dissimilar and depended on cartilage localization and age of the donors. Impairments in the rate of chondroitin sulfate sulfatation were detected in achondrogenesis of the II type and in diastrophic dysplasia; an extraction ability and amount of proteoglycan fractions, relative content of glycosaminoglycans and binding proteins were altered in some other forms of osteochondrodysplasias. Numerous biochemical markers of extracellular matrix deterioration were detected, which are typical for various morphofunctional alterations in hyalin cartilage--hyperproliferative reactions, tissue prematuration, persistence of the embryonal type of metabolism.

Gliosarcoma with cartilage formation

A case of gliosarcoma with cartilaginous component is described. Immunohistochemical and electron microscopic studies confirmed the presence of glial and fibroblastic elements. A major part of the sarcomatous tissue was undifferentiated and not labeled by any of the markers used including those for endothelial cells. The cartilage cells also were not labeled either by antiglial fibrillary acidic protein or any other marker. The occurrence and histogenesis of cartilage in gliomas and gliosarcomas have been reviewed.

Presence of osteonectin/SPARC in mandibular condylar cartilage of the rat

Osteonectin/SPARC was most abundantly present in adherent osseous tissue of the cartilage explants. In cartilage explants with ossification fronts, it appears to be present in hypertrophic chondroblasts and in the mineralised extracellular cartilage matrix. In a number of cartilage explants it could be demonstrated in the fibroblastic cells of the perichondrium and, intra- and extracellularly, in cartilage located adjacent to the perichondrium. In young mandibular condylar cartilage (20 days post-conception up to 7 days of age) osteonectin/SPARC was characteristically present in the transitional zone, a small area of differentiating skeletoblasts. In cartilage, osteonectin/SPARC might play a role in the process of mineralisation and subsequent replacement by bone. It seems to be an important marker of skeletal differentiation processes.

Identification of the cartilage alpha 1(XI) chain in type V collagen from bovine bone

Type V collagen prepared from bovine bone was resolved into three distinct alpha-chains by high performance liquid chromatography and gel electrophoresis. Peptide mapping established two chains as alpha 1(V) and alpha 2(V) as expected and the third as the cartilage alpha 1(XI) chain (previously thought to be unique to cartilage). In adult bone, the type V collagen fraction was richer in alpha 1(XI) chains than in fetal bone (about 1/3 of the chains in the adult). How these polypeptides are organized into native molecules is not yet clear, though the stoichiometry suggests cross-type heterotrimers between the type V and XI chains.

Chains of matrix-derived type X collagen: size and aggregation properties

Type X collagen was isolated from extracts of embryonic chick cartilages by immunoprecipitation and subsequently analyzed by SDS-PAGE. Most of the chains migrated with a molecular weight of 59 kDa, suggesting that the matrix form of type X collagen has not undergone post-secretory proteolytic processing. Minor amounts of material were also observed at 120 kDa, 70 kDa and 50 kDa. These were dimers or limited proteolytic products of type X chains.

Cartilage contains mixed fibrils of collagen types II, IX, and XI

The distribution of collagen XI in fibril fragments from 17-d chick embryo sternal cartilage was determined by immunoelectron microscopy using specific polyclonal antibodies. The protein was distributed throughout the fibril fragments but was antigenically masked due to the tight packing of collagen molecules and could be identified only at sites where the fibril structure was partially disrupted. Collagens II and IX were also distributed uniformly along fibrils but, in contrast to collagen XI, were accessible to the antibodies in intact fibrils. Therefore, cartilage fibrils are heterotypically assembled from collagens II, IX, and XI. This implies that collagen XI is an integral component of the cartilage fibrillar network and homogeneously distributed throughout the tissue. This was confirmed by immunofluorescence.

Differential stimulation of collagenase and chemotactic activity in fibroblasts derived from rat wound repair tissue and human skin by growth factors

Epidermal growth factor and cartilage-derived basic fibroblast growth factor (EGF and CD-bFGF) are mitogens shown to increase the rate of wound repair in animal models. In addition to being a mitogen for granulation tissue, CD-bFGF stimulates the recruitment of cells to the wound site. CD-bFGF and a closely-related chondrosarcoma-derived fibroblast growth factor stimulated chemotaxis of granulation tissue cells in vitro, each factor having a maximum activity at a concentration of 55 pM. Epidermal growth factor was also a potent chemoattractant for rat granulation tissue fibroblasts; however, maximum activity was obtained at 1.7 nM. Cells from all stages of wound repair were chemotactically responsive to these factors, but there was some attenuation of the response to bFGF in cells derived from fully-organized day 28 granulation tissue. Collagenase-catalyzed restructuring of collagen, an additional significant feature of wound repair, is probably critical to cell movement in an extracellular matrix. Cells derived from organizing (6-day old) sponge granulation tissue secreted latent collagenase constitutively in vitro. In the presence of serum, the production of collagenase was stimulated three-four fold by 1.8 nM bFGF derived either from cartilage or chondrosarcoma. When serum was present, as at a wound site, collagenase production was not enhanced by the addition of EGF. Cells from fully organized, day 21 sponge granulation tissue did not secrete latent collagenase constitutively and could not be stimulated to do so by the addition of EGF, bFGF, or phorbol ester. Human skin fibroblast collagenase production was also stimulated by bFGF and was refractory to EGF. While both classes of growth factor have the ability to promote wound healing, the varying responses they elicit in cell populations from the wound site emphasize the different pathways of cellular activation.

Association of the C-propeptide of type II collagen with mineralization of embryonic chick long bone and sternal development

Several proteins may play a role in bone formation. The C-propeptide of type II collagen is intimately associated with endochondral bone formation in bovine growth plate. We have used an antibody against this peptide to determine its immunofluorescent distribution in early stages of embryonic chick limb development with emphasis on first bone formation which occurs in the mid-diaphyseal region. The C-propeptide II is first evident by immunofluorescent localization at stage 27 (day 5-6) of embryonic tibia development with chondrocytes in the central mid-diaphysis. In subsequent stages, there is an increase in the number of chondrocytes in which it is localized in discrete vacuoles. Up to stage 30, immunofluorescence is observed intracellularly, after which it appears in the matrix. The released C-propeptide II appears to remain only transiently associated with the cartilage matrix and becomes concentrated in the calcifying periosteum, the region outside of the cartilage core where bone formation first occurs in a sequence of events comparable to intramembranous bone formation. These observations can be reproduced in cultures of stage 35 hypertrophic chondrocytes (core cells) and periosteum cells (collar cells). Core cells contain intensely stained intracellular vacuoles while collar cells are negative, although the collar cell osteogenic matrix concentrates exogenously added C-propeptide II. Double label immuno-staining shows that the C-propeptide II, unlike type II collagen and proteoglycan, which are secreted and incorporated into extracellular sites, is initially stored in intracellular vacuoles. The matrix localization of the C-propeptide II during the transition from cartilage to bone indicates a close association with the initiation of mineralization events of cartilage and bone and its specific origin in chondrocytes and not osteoblasts. These observations suggest that the C-propeptide II made by chondrocytes is associated with the formation of bone.

Cartilage content of an immature dog

The near total mineral-free and elastin-free cartilage content of a three-month-old mongrel dog was 0.73% of the dry body weight. Extraarticular (costal, tracheobronchial, thyroid, cricoid, nasal septum) cartilage constituted 0.44%; articular, 0.06; intervertebral disc, 0.10; elastic, 0.12 and meniscal fibrocartilage, 0.01%. Articular tissue accounted for only 7.25% of the total cartilage uronic acid. This is the first estimate of the amount and distribution of cartilage in a vertebrate species.

Structural similarity of hyaluronate binding proteins in brain and cartilage

A glial hyaluronate-binding protein (GHAP) was isolated from human brain white matter by affinity chromatography on immobilized hyaluronate. The 60 kDa protein appeared remarkably homogeneous by reversed-phase high pressure liquid chromatography analysis. Four cyanogen bromide peptides and 10 tryptic peptides were characterized by amino acid sequence, a total of 12 sequences since overlaps were found between 2 cyanogen bromide and 2 tryptic peptide sequences. Two sequences of brain GHAP had similarity with rat link protein, a hyaluronate binding protein in cartilage. The region of similarity was contained in the evolutionary conserved COOH-terminal half of link protein which is involved in the binding of hyaluronate. The remaining 10 amino acid sequences of brain GHAP had no similarity with link protein, nor with previously reported protein sequences. The findings suggest that the hyaluronate binding domains of such diverse proteins as brain GHAP and cartilage link protein are similar, probably due to the fact that hyaluronic acid is highly conserved in evolution.

Quantitation of component proteoglycans during long-term organ explant culture of human osteoarthritic hip cartilage

Cartilage from 14 human osteoarthritic femoral heads was studied in vitro 1, 20, and 30 days after explantation to assess component proteoglycans. Newly synthesized proteoglycans labeled with tritiated-leucine or Na(2)35SO4 and existing, hexuronate-containing proteoglycans were eluted on Sepharose CL-2B (0.5 mol/L sodium acetate, pH 5.8) as four subpopulations with average partition coefficients ranging from 0.05 to 0.9. These subpopulations were comprised of proteoglycans aggregated to hyaluronic acid and principally nonaggregated proteoglycans. Although this distribution was stable to day 20, by day 30, 35SO4-labeled proteoglycan aggregate decreased and smaller proteoglycans increased in amount. With longer culture periods, the proteoglycan subpopulations contained fewer high-density proteoglycans, which were also decreased in size.

Improved chondrocyte morphology and glycogen retention in the secondary center of ossification following osmium-potassium ferrocyanide fixation

The use of osmium-potassium ferrocyanide as the secondary fixative greatly improved chondrocyte preservation and stabilized the cartilage matrix proteoglycan. The proteoglycan was similar in appearance to that seen following fixation in the presence of cationic dyes. Extensive glycogen preservation was noted in these cells, occupying the area prior to and during the formation of the secondary center of ossification. The volume and organization of the glycogen within the cell cytoplasm were greater than that following buffered osmium fixation, and the cellular vacuoles within were greatly reduced. The cells forming the secondary center prior to the onset of mineralization were of greatest interest, because other studies compared them with the primary growth plate and described them as showing signs of hypertrophy as early as 5 days postnatally, as is found in the primary growth plate. Our observations indicate that glycogen is present in these cells, and cellular enlargement was not present. The cells do not resemble the hypertrophic chondrocytes of the primary growth plate, as far as cytoplasmic content is concerned, and we suggest that they may contribute to the development of the secondary center in a different fashion.