High-pressure X-ray diffraction, Mössbauer, and Raman studies in the antiferromagnetic insulators RFeO3 orthorhombic perovskites (R = Pr, Eu, Lu) disclose an unusual phenomena of a reversible first-order isostructural phase transition around 50 GPa concurring with an abrupt ∼ 5% volume decrease. It is shown experimentally that this transformation concurs with, and is driven by, a high-to-low-spin

Short term cultures were carried out with chondrocytes and tissue fragments from fetal guinea pig epiphyseal cartilage. Proteoglycans were isolated from these cultures and their properties were compared with those of pro-teoglycans from adult hyaline cartilage. It was concluded that the proteoglycans synthesized in culture were essentially similar to those present in cartilage matrix in vivo. The

Chondrocytes obtained from epiphyseal cartilage of fetal guinea pigs or ear cartilage of young rabbits were cultured in monolayer. The influence of colchicine, cytochalasin B, and p-nitrophenyl-β-d-xylopyranoside on secretion of proteoglycans was investigated. Radioactive sulfate was used as a precursor. As observed previously in other systems, β-d-xylosides initiated the synthesis of free chondro

Chondrocytes from rabbit ear cartilage were isolated and cultured as monolayers in Ham's F-12 medium. The proteoglycans synthesized by short-term cultures formed a high proportion of aggregates and contained chrondroitin-4- and -6-sulfate in a 2:1 proportion. Dermatan sulfate was not present. The average molecular weight of the chondroitin sulfate was about 20,000. Keratan sulfate with an average

The precursors, [ 35S]sulfate and [2- 3H]mannose, were used to study the biosynthesis of keratan sulfate and other oligosaccharides on proteoglycans isolated from Day 8 cultures of chick limb bud chondrocytes. After alkaline borohydride treatment, three fractions with sialic acid were separated by molecular sieve chromatography. The first contained keratan sulfate which was purified by digestion w

Proteoglycan monomer and link protein isolated from the Swarm rat chondrosarcoma both contain glycosylamine-linked oligosaccharides. In monomer, these N-linked oligosaccharides are concentrated in a region of the protein core which interacts specifically with both hyaluronate and link protein to form proteoglycan aggregates present in the cartilage matrix. Chondrocyte cultures were treated with tu

The core protein of proteoglycans from cartilage is substituted with glycosaminoglycans as well as N- and O-glycosidically linked oligosaccharides. We have taken advantage of the long intracellular half-life of the core protein precursor to the rat chondrosarcma proteoglycan to study the temporal relationship between the addition of the chondroitin sulfate chains and the O-linked oligosaccharides

macular corneal dystrophy is a human genetic disorder characterized by corneal opacities that arise, in part, from a failure to synthesize mature keratan sulfate proteoglycans. The macromolecules in macular corneas and in keratoconus corneas, an abnormality not involving proteoglycans, were biosynthetically labeled with [3H]mannose and [14C]glucosamine in organ culture, and the keratan sulfate pro

Chondrocytes isolated from the Swarm rat chondrosarcoma were incubated in culture with [1-3H]glucose for 30 min to 8 h. Labeled proteoglycans were isolated, treated with borohydride under alkaline conditions, and the three complex sugar structures purified: N- and O-linked oligosaccharides and chondroitin sulfate chains. The amount of incorporated radioactivity into each component sugar was analyz

Methods were developed for the separation of radioactively labeled carbohydrate components of proteoglycans by isocratic ion-moderated partition HPLC. Neutral sugars were separated after hydrolysis in trifluoroacetic acid with baseline separation between glucose, xylose, galactose, fucose, and mannose. N-Acetylneuraminic acid, N-acetylated hexosamines, glucose, galactose, and xylitol were likewise

Rabbit α1-microglobulin was purified from the urine of sodium-chromate-treated animals by the use of gel chromatography on Sephadex G-100 affinity chromatography on concanavalin-A - Sepharose and ion-exchange chromatography on DEAE-Sephadex. Rabbit α1-microglobulin had a molecular mass of 25.6 kDa on SDS/polyacrylamide gel electrophoresis. α1-microglobulin has previously been purified from the uri

Rabbit and rat bone matrix were implanted in athymic rat muscle, and the bone yield was measured as total calcium content after 4, 6, and 8 weeks. Matrix from both species induced equal amounts of new bone in the athymic rat. In rabbit and normal rat, the xenogenic matrix induced little or no bone formation. Thus, in the case of rabbit and rat, bone induction is species specific due to immunogenic

Extraskeletal bone formation can be induced in rodents by implantation of demineralised bone matrix and such implantation has been used to treat bone defects in man, but it is uncertain if induction or merely conduction occurs. We studied bone induction in primates by excising segments of the fibulae of adult squirrel monkeys, defatting and demineralising them before reimplanting them into the qua