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Biomedical subjects

B V Treadwell

Publications and source records attributed to B V Treadwell.

At least 37 records · Page 2Linked to original sources
PubMed1986

Degradative enzyme systems in cartilage.

There appears to be a final common pathway in the pathogenesis of osteoarthritis, regardless of the initiating cause. This involves an increase in degradative enzymes that arise from the cartilage. Both proteoglycan- and collagen-degrading enzymes, active at a neutral pH, increase in proportion to the severity of the arthritis until a final end-stage state is reached. This increase in enzyme activity may be triggered by release of a synovial messenger protein similar to interleukin-1. It is suggested by studies in an animal model that inhibition of these enzymes could lead to treatment of osteoarthritis.

Animals↗
PubMed1986

The synthetic processes of articular cartilage.

The cells of cartilage are constantly remodeling the matrix in which they are suspended. The stimulus to initiate remodeling is probably the chondrocyte's response to physical and or chemical changes in the environment. Heat, pressure, friction, load, pH, and growth are examples of such factors, which, if altered, would have a dramatic effect on the cell's state of health. The mode of response by the chondrocyte is specific for a given stimulus. Elevated temperature, for example, switches on a set of genes, the heat shock genes, in chondrocytes. This results in the synthesis of a series of cellular protein that presumably in turn protects the cell from the injurious effects of heat. Load and pressure affect both the synthetic rate of matrix protein and the degradation rates of preexisting matrix. A number of low-molecular-weight proteins appear to be involved in anabolic and catabolic processes of cartilage. A protein recently isolated from synovium stimulates the synthesis of degradative enzymes in cartilage. This factor is probably involved in the remodeling process under normal physiologic conditions. More recently, it has been found in elevated levels under pathologic conditions such as in the synovial fluid of patients with rheumatoid and osteoarthritis. The mechanism by which this factor turns on the degradative pathway appears complex and is under investigation.

Arthritis, Rheumatoid↗
PubMed1985

Stress-induced proteins in chondrocytes from patients with osteoarthritis.

Recent studies have shown that a specific set of proteins is produced by a variety of cells after the application of some forms of stress, including heat shock. Human chondrocytes isolated from cartilage with moderate to severe osteoarthritis synthesize at least 1 of these stress proteins (Mr 70,000) at physiologic temperature (37 degrees C), whereas chondrocytes isolated from non-pathologic cartilage synthesize this protein only in response to incubation at temperatures above 39 degrees C. The active synthesis of this protein (SP-70) at 37 degrees C is positively correlated with the severity of osteoarthritis and can be a characteristic indicator of this degenerative disease. We identified the active synthesis of stress proteins after incubating the cartilage tissue in medium containing 35S-methionine and separating the cell-associated proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The radioactive proteins were visualized by autoradiography. Analysis of the longevity of cell-associated proteins was determined by pulsing the tissue with 35S-methionine, and after different periods of chase in medium, the proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Specific proteins bands were then excised, and the radioactivity was determined by liquid scintillation counting.

Autoradiography↗
PubMed1985

Induction of heat-shock protein synthesis in chondrocytes at physiological temperatures.

Induction of heat-shock protein (HSP) synthesis is demonstrated in cultured calf-chondrocytes at temperatures shown to occur in normal human cartilage during experiments subjecting intact cadaverous hip joints to the parameters of level walking. A 70,000 MW heat-shock protein (HSP-70) is synthesized by chondrocytes at temperatures above 39 degrees C, while induction of synthesis of a 110,000 MW HSP only occurs at temperatures of 45 degrees C or greater. These differences in critical temperatures for induction, and data showing differences in kinetics of induction and repression of synthesis, suggest that there are differences in the mechanism of induction of the two HSPs. The duration of HSP synthesis and inhibition of synthesis of normal cellular proteins is directly proportional to the duration and magnitude of the temperature rise. Possible relationships between these new findings and the initiation and progression of degenerative joint disease are discussed.

Animals↗
PubMed1984

Insulin promoted decrease in the phosphorylation of protein synthesis initiation factor eIF-2.

Insulin stimulates cellular protein synthesis in calf chondrocytes in suspension culture. This enhanced synthetic activity is seen in association with a decrease in phosphorylation of the alpha subunit of protein synthesis initiation factor eIF-2. [32P] associated with the alpha subunit is reduced approximately 50% by insulin treatment of chondrocytes incubated in [32P] containing media. Identical or closely located amino acids in the eIF-2 alpha subunit are phosphorylated by the chondrocyte kinase(s) and the rabbit reticulocyte hemin regulated kinase as indicated by comparative peptide fragment analysis of [32P] labeled alpha subunits.

Animals↗
PubMed1984

Biochemical and metabolic abnormalities in normal and osteoarthritic human articular cartilage.

Incorporation of radioactive precursors into macromolecules was studied with human normal and osteoarthritic articular cartilage organ culture. Analysis of the salt extracted matrix components separated by cesium chloride buoyant density gradient centrifugation showed an increase in the specific activities of all gradient fractions prepared from the osteoarthritic cartilage. Further analysis of these fractions showed the osteoarthritic cartilage contained 5 times as much sulfate incorporated into proteoglycans, and an even greater amount of 3H-glucosamine incorporated into material sedimenting to the middle of the gradient. Greater than half of this radioactive middle fraction appears to be hyaluronate, as judged by the position it elutes from a DEAE column and its susceptibility to hyaluronidase digestion. This study supports earlier findings showing increased rates of macromolecular synthesis in osteoarthritis, and in addition, an even greater synthetic rate for hyaluronic acid is demonstrated.

Carbon Radioisotopes↗
PubMed1983

Comparative rates of proteoglycan synthesis and size of proteoglycans in normal and osteoarthritic chondrocytes.

Normal human and osteoarthritic cells were isolated from cartilage with clostridial collagenase. The cells were grown in media as a suspension culture in the presence of 35SO4. Osteoarthritic cartilage of moderate histologic grade (4-8) yielded chondrocytes which incorporated 35SO4 at a rate 3-4 times greater than did normal chondrocytes. The rate of incorporation, however, decreased to normal levels with chondrocytes isolated from mild (grade 0-3) or more advanced (grade 9-13) stages of the disease. These results corroborate those obtained in earlier studies using organ cultures and show that when osteoarthritic cells are isolated from their matrix environment, they continue to synthesize macromolecules at an increased rate. Analysis of the material synthesized by the isolated cells on sizing column demonstrated an inverse relationship between the size of the 35SO4 containing molecules and the severity of the disease.

Animals↗
PubMed1983

Irrigating solutions for arthroscopy. A metabolic study.

UNLABELLED: In an effort to determine the optimum solution for irrigation during arthroscopic procedures, an in vitro metabolic experiment was performed in which cartilage slices were incubated with 35SO4 in various commercially available solutions, harvested at regular intervals, and assayed for incorporated radioactivity. The solutions were compared with Ham F12 medium, a complex, ionically balanced salt and amino-acid solution that is used for tissue culture. The data show that neither normal saline or phosphate-buffered saline supports metabolic activity as well as Ringer lactate or acetate, both of which approximate the values for the control, Ham F12 solution. CLINICAL RELEVANCE: Arthroscopy and arthroscopic surgical procedures have become commonplace in orthopaedic practice. Normal saline solution, commonly used in large quantities as an irrigating solution, is in fact not physiological, and we showed that it inhibits normal synthesis of proteoglycan by the chondrocytes. Ringer lactate seemed to support cartilage metabolism as well as an "ideal" tissue-culture medium (Ham F12 solution). Since Ringer solution and normal saline cost the same in our hospital, we strongly recommend that this more physiological solution be used for arthroscopic procedures.

Animals↗
PubMed1982

Characterisation of human articular cartilage link proteins from normal and osteoarthritic cartilage.

Proteoglycan link proteins were isolated from human articular cartilage obtained from normal and osteoarthritic femoral heads and purified to homogeneity employing a method previously described by this laboratory. The link proteins were analysed for amino acid composition, molecular weight on sodium dodecyl sulphate polyacrylamide gels, and ability to stabilise proteoglycan aggregates. The results of these studies were compared with those obtained with bovine link proteins. Two link proteins were identified in the purified fraction from normal and osteoarthritic human cartilage with apparent molecular weights of 54 000 (link 1) and 48 000 (link 2). Functionally the link proteins, isolated from osteoarthritic and normal cartilage, were indistinguishable as measured by their ability to stabilise aggregate. The amino acid compositions of normal and osteoarthritic link proteins were also found to be similar to each other but significantly different from the amino acid composition reported for the bovine link proteins. The quantities of these proteins in extracts from normal and diseased tissue were similar, as was the ratio of link protein 1 to link protein 2.

Aged↗
PubMed1980

De novo protein synthesis by human chondrosarcoma in cell and organ culture: evidence of unusually high collagen production by a neoplastic tissue.

Protein synthesis by human chondrosarcoma tissue and normal articular cartilage was studied in organ and primary monolayer cell culture systems. Protein synthesis by cell cultures was evaluated at 2.7 and 21 days after plating. When compared to normal, incorporation of 3H-proline and 35S-methionine into proteins was elevated in chondrosarcoma samples under both culture conditions. Hydroxyproline analyses of tissue hydrolysates indicated that chondrosarcoma samples contained significantly less collagen than normal articular cartilage, yet were incorporating significantly greater amounts of 3H-proline into 3H-hydroxyproline. Collagen production by cell cultures was assessed by digestion of samples with purified clostridial collagenase. Chondrosarcoma cells produced more collagenase-sensitive protein than normal cells at all intervals. SDS polyacrylamide gel analyses of all preparations showed two collagenase-sensitive proteins with apparent molecular weights of 165,000 and 175,000. Decreased synthesis of another major protein, apparent molecular weight 210-220,000 was noted in chondrosarcoma preparations in both culture systems.

Bone Neoplasms↗
PubMed1977

DNA-directed in vitro synthesis of beta-galactosidase. Studies with purified factors.

The phage DNA-directed synthesis of beta-galactosidase has been examined in a system containing the following purified Escherichia coli factors: RNA polymerase; cyclic AMP receptor protein; N10-formyltetrahydrofolate Met-tRNAf transformylase; initiation factors 1, 2, and 3; elongation factors Tu, Ts, and G; release factors 1 and 2; 20 aminoacyl-tRNA synthetases; L factor (Kung, H. F., Spears, C., and Weissbach, H. (1974) J. Biol. Chem. 250, 1556-1562); and Lalpha (Kung, H.-F., Spears, C., and Weissbach, H. (1976) Fed. proc. 35, 1537). Under these conditions, beta-galactosidase synthesis occurs at less than 1% of the rate obtained with unfractionated extracts, which suggested that other required components were lacking. The difficulty in obtaining large amounts of the purified aminoacyl-tRNA synthetases for these studies made it necessary to modify the system. It was possible to conserve many of the purified aminoacyl-tRNA synthetases since at least 13 of them could be replaced by an Ehrlich ascites extract. The ascites extract plus other E. coli purified factors was used as a basic system to search for additional components required for beta-galactosidase synthesis. The present report describes the purification from E. coli extracts of three fractions, called Lbeta, Lgamma, and Ldelta, that are needed to restore enzyme synthesis.

Amino Acyl-tRNA Synthetases↗
PubMed1977

DNA-directed synthesis in vitro of beta-galactosidase: requirement for a ribosome release factor.

The DNA-directed synthesis of beta-galactosidase in Escherichia coli extracts has been investigated in a partially fractionated system. A dependency was obtained for 3',5'-cyclic AMP receptor protein and also for a factor, from the salt wash of ribosomes, that has been purified to near homogeneity. This factor has been identified with a ribosome release factor previously purified from the supernatant fraction by A. Hirashima and A. Kaji [(1972) Biochemistry 11,4037-4044]. In the coupled transcription-translation system this factor stimulates beta-galactosidase synthesis and total protein synthesis 2- to 4-fold. It is thus clear that the ribosome release factor has a physiological function in translation. It may also affect transcription, because it stimulated total RNA synthesis up to 50% in this in vitro system.

Cross Reactions↗