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Biomedical subjects

E D Harris

Publications and source records attributed to E D Harris.

At least 181 records · Page 10Linked to original sources
PubMed1972

A collagenolytic system produced by primary cultures of rheumatoid nodule tissue.

A collagenase and a neutral protease have been insolated and characterized from primary cultures obtained from rheumatoid subcutaneous nodules. Release of both active enzymes was maximal between the 3rd and 7th days of culture and was stimulated by the presence of small amounts of colchicine (0.1 mug/ml) added to the culture medium. Both the protease and the collagenase from nodule tissue were active at physiologic pH and were inhibited by chelating agents, sulfhydryl compounds, and 1:40 dilutions of human serum. Both enzymes appeared to have a molcular size equivalent to similar enzymes found in cultures of rheumatoid synovium. The nodule collagenase was purified by chromatography on molecular sieve columns followed by affinity chromatography. The pure enzyme cleaved collagen in solution at 24 degrees C at the locus common for mammalian collagenases to act: three quarters of the distance from the amino-terminus. Under the same conditions the purified enzyme cleaved gelatin (denatured collagen) at the same locus. It is likely therefore that the collagenase in rheumatoid connective tissues functions to produce the initial cleavage of collagen and that after the initial reaction products are denatured, proteases digest them into smaller polypeptides more rapidly than does the collagenase itself. Since rheumatoid nodules grow centrifugally at the expense of the palisading fibroblast layer it seems possible that the central necrotic areas are caused by release of collagenase and protease from the highly cellular palisading zone resulting in the destruction of the extracellular collagen matrix.

Arthritis, Rheumatoid↗
PubMed1970

Urinary polypeptides related to collagen synthesis.

Of the total urinary hydroxyproline in normal subjects and those with skeletal disorders, between 4 and 20% was nondialyzable. In some patients with Paget's disease of bone, hyperparathyroidism with osteitis fibrosa, hyperphosphatasia, and extensive fibrous dysplasia the total urinary hydroxyproline was sufficiently high to permit purification of this polypeptide hydroxyproline by gel filtration and ion exchange chromatography. The partially purified polypeptides had molecular weights between 4500 and 10,000 and amino acid compositions and physical properties resembling those of gelatin. The polypeptide fractions also contained neutral sugar and glucosamine. These fragments had been shown to be susceptible to cleavage by purified bacterial collagenase suggesting the presence of the sequence-Pro-X-Gly-Pro-Y-. After administration of proline-(14)C to patients with Paget's disease hydroxyproline-(14)C was excreted in the urine. The hydroxyproline-(14)C specific activity reached a peak in 2-4 hr and declined rapidly. The specific activity of the polypeptide (retentate) portion was severalfold greater than that of the raw urine and diffusate. When the labeled urines were subjected to gel filtration the hydroxyproline-(14)C fractions of highest molecular weight which were eluted first from the columns had the highest specific activities. Exposure of the hydroxyproline-(14)C-containing polypeptides to bacterial collagenase rendered them dialyzable. Four patients with hyperparathyroidism and osteitis fibrosa were studied before and after removal of a parathyroid adenoma, a period of transition from a predominance of bone collagen resorption to one of relatively increased bone collagen synthesis. The total urinary hydroxyproline fell rapidly after operation whereas the ratio of the polypeptide fraction to the total rose three- to fourfold. The results of these studies suggest that the urinary polypeptides represent fragments of collagen related to collagen synthesis. Changes in the ratio of these peptides to total hydroxyproline in the urine may serve as an index of new bone formation in patients with skeletal disorders.

Adenoma↗
PubMed1969

Collagenases in human synovial fluid.

An enzyme which degrades native collagen at neutral pH has been isolated from cultures of rheumatoid synovium in vitro, but little or no collagenolytic activity has been found in homogenates of fresh rheumatoid synovium. Similar to most other mammalian collagenases this synovial enzyme is readily inhibited by serum proteins. Proteins of synovial fluid are derived largely from serum and synovial fluid from noninflamed joints was found to inhibit synovial collagenase; the inhibitor was destroyed by trypsin, but not by hyaluronidase. Inhibitory activity was reduced in approximately one-half of the fluids from patients with rheumatoid arthritis. In a total of nine synovial fluids, collagenolytic activity was detectable. This activity was not present in constant amounts in synovial fluids aspirated at different times from the same patient and tended to vary inversely with the titer of inhibitory proteins. The collagenolytic activity in the synovial fluids from different patients was variably inhibited by serum proteins. Two distinct collagenases were detected in some rheumatoid synovial fluids and separated by gel filtration. One, labeled "B" enzyme, with an estimated molecular weight 20,000-25,000 resembled the collagenase obtained from synovial cultures. The other, labeled "A" enzyme degraded collagen fibrils as well as collagen in solution. Disc electrophoresis on acrylamide gels and electron microscopy of segment long spacing (SLS) aggregates of reaction products of the enzymes at 27 degrees C demonstrated that both "A" and "B" enzymes cleaved collagen molecules at a point three-quarters from the amino terminal end of the molecule. Thus collagen degradation in rheumatoid arthritis could result from the operation of these two collagenases.

Arthritis, Rheumatoid↗
PubMed1967

Collagen-like fragments: excretion in urine of patients with Paget's disease of bone.

Patients with Paget's disease of bone excrete, in the urine, polypeptides that have amino acid composition and other properties resembling those of fragments of collagen. The pattern of isotope incorporation in vivo suggests that these fragments are derived from collagen that has been synthesized and rapidly degraded, or that they are rapidly synthesized but not incorporated into tropocollagen molecules.

Amino Acids↗