Search PubMed⌕ Search

Biomedical subjects

H S Cheung

Publications and source records attributed to H S Cheung.

At least 109 records · Page 6Linked to original sources
PubMed1981

"Milwaukee shoulder"--association of microspheroids containing hydroxyapatite crystals, active collagenase, and neutral protease with rotator cuff defects. II. Synovial fluid studies.

Hydroxyapatite crystals in spheroid-shaped masses 1.9-15.6 micrometer in diameter were found in 12 of 13 synovial fluids obtained from the shoulder joints of 4 patients with rotator cuff tears and glenohumeral osteoarthritis. Two of 16 control joint fluids also showed these particles. Collagen types I, II and III were identified in the joint fluid pellets from 3 of the 4 patients, and fibers with typical collagen periodicity were also seen on transmission electronmicroscopy. Collagenase and neutral protease activities were found in fluids from 5 joints in 3 patients, whereas active collagenase was found in only 1 of 10 fluids from rheumatoid arthritis patients and in none of 3 fluids from patients with osteoarthritis. Neutral protease activities were present in several rheumatoid joint fluids. These findings are compatible with the hypothesis of an enzymatic release of hydroxyapatite crystals from the synovium and endocytosis by synovial macrophage-like cells with subsequent crystal-stimulated release of collagenase and neutral protease into the joint fluid, completing a pathogenetic cycle.

Aged↗
PubMed1981

"Milwaukee shoulder"--association of microspheroids containing hydroxyapatite crystals, active collagenase, ad neutral protease with rotator cuff defects. III. Morphologic and biochemical studies of an excised synovium showing chondromatosis.

Synovial tissue excised from the unstable right shoulder joint of a patient with an absent rotator cuff, severe glenohumeral joint degeneration, and hydroxyapatite-containing microspherules, collagen types I, II, and III, active collagenase, and neutral protease in the joint fluid showed extensive osteochondromatosis histologically. Electronmicroscopy revealed calcific foci in microvilli which could easily escape into the adjacent joint space through areas denuded of synovial cells. Fibrocytes demonstrated intensive pinocytotic activity of unknown significance. Energy dispersive analysis showed elemental ratios consistent with hydroxyapatite. A literature review suggested some relationships between the various pathologic lesions present in this joint. Whether similar synovial changes exist in the opposite shoulder joint of this patient and in 3 other subjects with nearly identical clinical, radiographic, and joint fluid findings is not known.

Aged↗
PubMed1981

Release of collagenase, neutral protease, and prostaglandins from cultured mammalian synovial cells by hydroxyapatite and calcium pyrophosphate dihydrate crystals.

Hydroxyapatite (HA) and calcium pyrophosphate dihydrate (CPPD) crystals were phagocytosed when added to cultured human rheumatoid or normal canine synovial cells. Collagenase and neutral protease secretion into the culture medium was increased 5- to 8-fold over control values in the presence of HA and increased 3-fold in the presence of CPPD crystals. HA but not CPPD crystals induced a 300-fold increase in human rheumatoid synovial cell culture fluid prostaglandin (PG) E2 levels and an 8-fold increase in PGF alpha levels. This mechanism may be important in the pathogenesis of the destructive arthropathies associated with HA and CPPD crystals.

Animals↗
PubMed1981

Release of pyrophosphate by normal mammalian articular hyaline and fibrocartilage in organ culture.

Calcium pyrophosphate dihydrate crystals are found most frequently in fibrocartilaginous tissue and to a lesser extent in hyaline articular cartilage. Previous investigators found that pyrophosphate (PPi) was released into the medium by immature rabbit hyaline cartilage and osteoarthritic human cartilage in organ culture but not by normal human or mature rabbit cartilage. By employing a sensitive fluorometric assay for PPi and correcting for hydrolysis of PPi during the incubations, we detected PPi release by all normal mammalian cartilage studied. PPi release per mg wet weight of lapine and canine cartilage was paralleled by uronic acid production. Meniscal fibrocartilage, the most common site of calcium pyrophosphate deposits, also elaborate PPi.

Animals↗
PubMed1980

Synovial origins of Rice bodies in joint fluid.

Rice bodies and synovia obtained from knee joints of rheumatoid arthritis patients were solubilized by limited pepsin treatment. The quantity of each type of collagen in both tissues was determined by differential salt precipitation, cyanogen bromide peptide analysis, and SDS polyacrylamide gel electrophoresis. Rice bodies and synovial membrane contained equal proportions of Type I and III collagens with trace amounts of Type "A-B" collagen.

Arthritis, Rheumatoid↗
PubMed1980

In vitro synthesis of tissue-specific type II collagen by healing cartilage. I. Short-term repair of cartilage by mature rabbits.

The healing of surgically induced defects in mature rabbits' hyaline cartilage was examined histologically and biochemically. The subchondral bone underneath the lesion was the source of repair. At the end of the first month, mushroom-shaped chondroid buds were seen sprouting from the subchondral bone. By the tenth week, these buds fused to a cartilagenous plug filling the lesion. The repaired cartilage synthesized Type II collagen.

Aging↗
PubMed1980

Identification of collagen subtypes in synovial fluid sediments from arthritic patients.

Collagen fibers in synovial fluid sediment were described a decade ago. Since then, tissue-specific collagen molecules (types) have been characterized. Techniques were devised to identify the collagen types in joint fluid sediment. Collagens were found in 12 of 17 pellets prepared from fluid aspirates from 17 knee joints of patients with various forms of arthritis. Collagen types I and III and polypeptide chains A and B (basement membrane collagen) were specifically identified in four of seven fluids from patients with active systemic lupus erythematosus (SLE) and in a single fluid from a patient with severe septic arthritis. This "collagen profile" was identical to that of rheumatoid synovium. Type II collagen, characteristic of hyaline articular cartilage, was found in two of six fluids from osteoarthritic joints. The presence of sufficient collagen (about 5 micrograms) to permit typing was correlated with roentgenographic evidence of joint space narrowing; the presence of the "synovial" collagen profile was correlated with decreased joint fluid pH.

Arthritis↗
PubMed1979

Design of potent and specific inhibitors of carboxypeptidases A and B.

The combination in one molecule of functional groups that can interact specifically with different substrate binding areas at the active site of carboxypeptidases A and B has led to the development of potent and specific inhibitors of these enzymes. 2-Benzyl-3-mercaptopropanoic acid (SQ 14,603) has a Ki of 1.1 x 10(-8) M vs. carboxypeptidase A and a Ki of 1.6 x 10(-4) M vs. the B enzyme. 2-Mercaptomethyl-5-guanidinopentanoic acid (SQ 24,798) has a Ki of 4 x 10(-10) M vs. carboxypeptidase B and a Ki of 1.2 x 10(-5) M vs. carboxypeptidase A. It is proposed that the sulfhydryl groups of these inhibitors bind to the catalytically important zinc ions of these enzymes, and that, in conjunction with the benzyl and guanidinopropyl side chains, they are responsible for their specificity.

3-Mercaptopropionic Acid↗
PubMed1978

Stimulation of fibroblast biosynthetic activity by serum of patients with pretibial myxedema.

Skin fibroblasts from the shoulder and lower extremities of normal individuals, as well as from patients with pretibial myxedema (PTM) were grown in culture. When cells reached the monolayer stage, they were labeled with 3H-glucosamine and tested for hyaluronic acid synthesis in the presence of either serum from PTM patients or normal human serum. All the fibroblasts from the pretibial area synthesized 2 to 3 times more hyaluronic acid when incubated with PTM sera than when incubated in normal human serum. Fibroblasts cultured from skin of the back or prepuce did not respond to PTM sera. This heat-stable, protease-sensitive, and dialyzable, fibroblast-stimulating factor is not a 7S gamma-globulin. The enhanced sensitivity to PTM sera exhibited by fibroblasts from the lower extremities may explain why the lesions in this disease are restricted primarily to that area.

Blood↗
PubMed1978

In vitro collagen biosynthesis in healing and normal rabbit articular cartilage.

To examine the repair collagens produced by cells in injured cartilage, the femoral articular surfaces of three groups of New Zealand white rabbits were injured by making both superficial and deep lacerations and drill holes. Eight weeks after surgery, the rabbits were killed and slices of injured articular cartilage were harvested. The types of collagen being synthesized at the site of these lesions were identified by labeling the recovered specimens in vitro with 3H-proline and by characterizing the collagen using sodium dodecyl sulphate electrophoresis, carboxymethyl cellulose chromatography, and cyanogen bromide peptide analysis. In all cases, tissue-specific type II ([alpha1 (II)]3) cartilage collagen was synthesized. Histological examination using toluidine blue showed that the chondrocytes bordering the cartilage defect produced by deep lacerations and drill holes responded by increased cellular activity, as shown by cell cloning and increased matrix staining. The drilled holes were completely filled by tissue with staining and morphological characteristics similar to those of hyaline cartilage.

Animals↗