Immunologic evidence of a bone morphogenetic protein in the milieu intérieur.

Eighteen different groups of proteins have been identified in the organic matrix of bone. To date, seven have been identified in circulating blood. Several plasma proteins are found to accumulate in bone matrix. Two bone, carboxyglutamic acid rich proteins (BGP or osteocalcin) and bone morphogenetic protein (BMP) are measured by RIA in serum in the range of ng/ml. Of all matrix groups, the least abundant is BMP. Acting as a paracrine or local hormone, BMP induces perivascular connective tissue cells of bone marrow to differentiate into cartilage and bone. Neither the mechanism of action or target cells, nor the mode of transport of BMP in serum are known, but the immunologic activity demonstrates higher serum BMP RIA levels in growing children and patients with Paget's Disease than in normal adults. Serum BMP is remarkably low in postmenopausal women with severe osteoporosis; serum anti-BMP antibody is correspondingly high. Although these observations are preliminary and based on a relatively small number of patients, the data suggest a working hypothesis that BMP and anti-BMP are bone tissue-specific parameters of normal and pathological bone physiology. The possibility of diagnosis of osteoporosis in the prefracture stage, and the prospects of evidence of an autoimmune response to the products of bone resorption, derived from the serum BMP anti-BMP ratio, warrant special investigation.

Hypoallergenic breads. Wheat content of products available in the San Francisco Bay area.

Substantial amounts of soluble wheat antigens have been found in breads sold as "wheat-free" in the San Francisco Bay Area. Physicians with patients on a wheat-free diet are urged to exercise careful supervision over their patients' choice of such breads.

Solubilized and insolubilized bone morphogenetic protein.

A bone morphogenetic protein (BMP) obtained in solution by digestion of demineralized rabbit cortical bone matrix with bacterial collagenase retains its biologically active conformation in a neutral salt/ethylene glycol mixture. BMP may be insolubilized by coprecipitation with calcium phosphate and resolubilized by chemical extraction with a neutral salt in the same solvent mixture. Upon concanavalin A-Sepharose chromatography, BMP is bound by hydrophobic interaction and carbohydrate recognition and is recovered by elution with either alpha-methyl mannoside or ethylene glycol solvent mixture. Implants of both eluates and the extracts of the coprecipitate in double-walled diffusion chambers induce transmembrane bone morphogenesis. BMP is not species specific; rabbit BMP induces new bone formation in the rat. The present observations indicate that BMP is a glycoprotein.

Beta-tricalcium phosphate delivery system for bone morphogenetic protein.

An aggregate of biodegradable beta-tricalcium phosphate and bone morphogenetic protein (BMP/TCP) induces the differentiation of cartilage within eight days, cartilage and woven bone within 12 days, and lamellar bone, including bone marrow, within 21 days. The yield of new bone from a 1-mg dose was more than 12 times greater from the TCP/BMP than from the BMP alone. Whether TCP acts as a slow-release delivery system, potentiates the activity of BMP, or serves to distribute BMP in a favorable three-dimensional pattern requires further investigation.

A bovine low molecular weight bone morphogenetic protein (BMP) fraction.

A low MW bone morphogenetic protein fraction (BMP) is quantitatively extracted from bovine bone matrix by an inorganic-organic CaCl2-urea solvent mixture and fractionated by ion exchange and gel chromatography. The BMP fraction induces differentiation of perivascular mesenchymal type cells into cartilage and bone inside the mouse's thigh, outside of double walled diffusion chamber, in muscle pouches in the rabbit anterior abdominal wall, and in 0.8 cm trephine defects in the rat's skull. Bovine BMP may consist of electrophoretic components ranging from 12 K to 30 K in MW. The main components correspond to a MW of 23 K, 18 K and 12 K when they are compared with the mobilities of standard proteins. Because it was invariably present in all of the fractions with osteoinductive activity, circumstantial evidence leads to a 17 to 18 K component for a BMP. The possibility of a diameter monomer system for BMP activity also warrants consideration. The polypeptide portion constitutes only about 80% to 85% of the dry weight of the mixture of the three electrophoretic components, and suggests that the BMP fraction contains glycoproteins. Characteristically, glycoproteins migrate anomalously on SDS gels and create doubt about whether the major bands represent true MW. Nevertheless, the data clearly point to the low MW protein fractions for the direction of future work on BMP.

Purification of bovine bone morphogenetic protein by hydroxyapatite chromatography.

Bovine bone morphogenetic protein (bBMP) induces differentiation of mesenchymal-type cells into cartilage and bone. bBMP has an apparent Mr of 18,500 +/- 500 and represents less than 0.001% of the wet weight of bone tissue. A Mr 34,000 protein resembling osteonectin is separated by extraction with Triton X-100. A Mr 24,000 protein and about half of a Mr 22,000 protein are disassociated from bBMP by precipitation in 1.5 M guanidine hydrochloride. Aggregates of bBMP and a Mr 14,000 protein are insoluble in aqueous media; the bBMP becomes soluble when the Mr 14,000 protein is disassociated in 6 M urea and removed from the solution by ultrafiltration. Three separate molecular species with apparent Mrs 18,500, 17,500, and 17,000 are eluted at 0.10, 0.15, and 0.20 M phosphate ion concentrations, respectively, from a hydroxy-apatite column. The Mr 18,500 protein has the amino acid composition of acidic polylpeptide and includes four half-cystine residues; the pI is 4.9-5.1. The Mr 22,000 component is a chromoprotein resembling ferritin. The NH2-terminal amino acid sequence of the Mr 17,500 protein simulates histone H2B. The Mr 17,000 protein may possess calmodulin activity. Aggregates of the Mr 18,500 and other proteins induce formation of large deposits of bone; the Mr 18,500 protein alone is rapidly absorbed and induces formation of small deposits. None of the other proteins induces bone formation.

Human bone morphogenetic protein (hBMP).

Human bone morphogenetic protein (hBMP) was chemically extracted from demineralized gelatinized cortical bone matrix by means of a CaCl2 X urea inorganic-organic solvent mixture, differential precipitation in guanidine hydrochloride, and preparative gel electrophoresis. hBMP is isolated in quantities of 1 mg/kg of wet weight of fresh bone, and has the amino-acid composition of an acidic polypeptide. The mol wt is 17 to 18 k-Da (kilodaltons). Implants of the isolated 17-kDa protein are very rapidly adsorbed and produce a smaller volume of bone than protein fractions consisting of 24-, 17-, and 14-kDa proteins. Since the isolated 24- and 14-kDA components lack hBMP activity, the kinetics of the bone morphogenetic processes including the function of other proteins as carrier molecules, await investigation.