Biomedical subjects
Publications and source records attributed to C W Castor.
The responsiveness of human synovial cells and chondrocytes to L-ascorbate, CTAP Ib, III, IV and V was assessed by assays which measured DNA and glycosaminoglycan synthesis and plasminogen activator formation. Differences in behavior were noted between synovial and cartilage derived cells and between normal and OA chondrocytes.
Connective tissue activating peptide (CTAP-III) is one of the growth factors found in the alpha granules of human platelets. This small cationic platelet protein shows several apparent isoelectric point variants after the preparative isoelectric focusing step in large scale preparations from multiple donors. Analytical isoelectricfocusing techniques under denaturing conditions, coupled with Western blotting and immunodetection, now show that CTAP-III prepared rapidly from single donors also has multiple isoelectric point variants, suggesting that this finding is more likely related to post-translational modification than preparative artifact or genetic polymorphism.
Connective tissue activating peptide III (CTAP III), a human platelet derived growth factor, induced marked stimulation of 2-deoxy[14C]glucose (2dG) uptake in cultures of human synovial cells, chondrocytes, and dermal fibroblasts. Cytochalasin B (2 X 10(-5) M) blocked the mediator-induced increase in 2dG uptake; phlorhizin (8 X 10(-4) M) partially inhibited this process. When cells were exposed to CTAP III (4 X 10(-6) M) for 30 min prior to uptake assay, 2dG uptake was stimulated by 30-110%; greater stimulation (400-800%) occurred following 17-40-h preincubation with the mediator. A 17-h exposure to CTAP III similarly stimulated 3-O-methylglucose uptake by over 400%, suggesting that CTAP III stimulated 2dG uptake is mediated via changes in hexose transport. Cycloheximide clearly prevented the 17-h effects of CTAP III on 2dG uptake. Insulin (3 X 10(-6) M) stimulated 2dG uptake 40-70% after 30-min preincubation with hormone; little effect was seen after 17-h preincubation. These data suggest that CTAP III stimulates glucose transport shortly after addition to target cells; the major stimulation observed after a 17-h incubation is consistent with the synthesis of new glucose transport protein.
Relatively sparse literature developed during the past 30 years that sought to characterize the relationship of rheumatoid arthritis to neoplasms. The past decade has seen added concern over possible oncogenic effects of cytotoxic agents now used to manage some patients with rheumatoid arthritis. Acquisition of unambiguous data is complicated by the fact that the cumulative incidence of cancer in the general population exceeds 30 percent, and that most studies have insufficient patient numbers, duration follow-up, and attention to age, sex, race, or known etiologic agents. Thus, it is not surprising to find reports that cancer incidence is high, low, or unchanged in rheumatoid arthritis. Although equally ambiguous data were accumulated concerning potential neoplasm-inducing effects of cytotoxic drugs, concern is justified in relation to increased frequency of bladder cancer after cyclophosphamide and acute leukemia following alkylating agents.
Women with rheumatoid arthritis performed 1 of 3 low intensity aerobic exercise protocols (15, 25, and 35 minutes) 3 times per week for 12 weeks. A nontraining group served as controls. All exercise groups improved their aerobic capacity, exercise time, and joint counts. Subjects described improvement in activities of daily living and reduced joint pain and fatigue. Exercise duration up to 35 minutes can be therapeutic, and as little as 15 minutes of exercise 3 times/week is sufficient to improve aerobic capacity in rheumatoid arthritis patients with severe limitations.
Explore the source record for details and available documents.
Antisera selectively reactive with the N-terminal tetrapeptide sequence of the platelet-derived connective tissue activating peptide-III mitogen were prepared and characterized. Solid phase synthesized Z-Asn-Leu-Ala-Lys(Z)-OH tetrapeptide representing the N-terminus of the mitogen was used as an immunogen after carbodiimide mediated coupling to methylated bovine serum albumin carrier and subsequent removal of Z groups. Anti-tetrapeptide sera demonstrated cross-reactivity to the mitogen but not beta-thromboglobulin, fibroblast growth factor, or epidermal growth factor, and a limited cross-reactivity to parathyroid hormone. The studies indicate that the N-terminal sequence of the mitogen is accessible for binding with antibody and the antitetrapeptide sera provide a reagent for the selective measurement of biologically active mitogen in the presence of structurally similar beta-thrombo-globulin. In addition, computer analysis of amino acid sequences revealed that few proteins contain the Asn-Leu-Ala-Lys sequence and of those that do, many are retroviral proteins or transforming polyproteins.
We evaluated the effect of strenuous aerobic exercise on joint symptoms and compared the functional capacity and muscle strength among patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and very sedentary matched controls. Strenuous ergometer exercise did not exacerbate joint symptoms in these patients. Isotonic leg extension and flexion as well as grip strength were diminished in the RA and OA subjects compared to controls (p less than 0.05). All subjects displayed low maximum oxygen consumption indicating reduced functional capacity. Acute bouts of strenuous exercise performed on bicycle ergometer do not appear harmful to the nonacute arthritis patient.
Connective tissue activating peptide III (CTAP-III) is a platelet factor that induces, in cultured connective tissue cells, activities observed in chronic inflammation. In this study we measured plasminogen activator secretion by synovial fibroblasts after stimulation by CTAP-III. Increased plasminogen activator secretion was observed 24-48 hours after stimulation. Induction was prevented by dexamethasone (10(-9)-10(-7) M), cycloheximide (1 microgram/ml) and, variably, by actinomycin D (0.3 microgram/ml), but not by cytosine arabinoside (10(-4)M). This is the first evidence that CTAP-III induces degradative as well as proliferative activity by connective tissue cells.
A protein factor in human urine which has the ability to activate connective tissue cells has been identified and partially purified; it appears to be different from epidermal growth factor and IgG. This urinary connective tissue activating factor (CTAP-U) is nondialyzable, labile to protease, stable to thiols, heat, and acid, and has an acidic isoelectric point. Purified preparations of CTAP-U have biologic activities that cause human connective tissue cells to synthesize incremental amounts of 14C-hyaluronic acid, 35S-proteoglycans, and 3H-DNA in vitro. The cell spectrum responsive to this substance includes human synovial cells, human chondrocytes, and skin fibroblasts. CTAP-U does not react with antisera to connective tissue activating peptide-III or to antibodies against IgG or its Fc and Fab fragments. Furthermore, CTAP-U does not cross-react in a radioreceptor assay for insulin, basic somatomedin, or epidermal growth factor-urogastrone. Utilizing standardized isolation conditions, CTAP-U preparations with these properties have been isolated from the urine of 6 normal individuals.
In this study, virtually all sulfated glycosaminoglycan (GAG) synthesized and secreted by human synovial cells, both normal and rheumatoid, was detected in the form of proteoglycans of monomeric size. Enzyme hydrolysis studies that were performed demonstrated dermatan sulfate to be the dominant GAG in the proteoglycan, with lesser amounts of chondroitin 4/6 sulfate. Exposure to beta-xyloside, used as a false "core protein," resulted in marked enhancement of GAG chain formation, suggesting that the synthesis of the sulfated carbohydrate chain itself was not rate limiting. Proteoglycan synthesis and secretion were stimulated by several types of connective tissue activating peptides (CTAP); CTAP-III stimulation of incremental core protein and glycosaminoglycan was shown to be of a similar magnitude. Since chain synthesis was not rate limiting, it is suggested that stimulated proteoglycan formation caused by the CTAP peptides may be primarily modulated through increased formation of core protein.
Four normal (NF) and 4 scleroderma skin fibroblast (SF) strains were compared with respect to 1) basal 14C-glucosamine and 35SO4-labeled glycosaminoglycan (GAG) synthesis, 2) responsiveness to autacoid mediators, and 3) performance following maximal stimulation. Under basal conditions, SF synthesized and secreted 2-3 times more radioactive hyaluronic acid than the NF (P less than 0.001); molecular volume by gel chromatography was similar and suggested a high molecular weight product. SF were essentially as responsive to normal lymphoid and platelet factors as were NF. No consistent qualitative or quantitative differences in sulfated GAG synthesis were noted between the 2 groups of cells. Incubation of NF and SF with a false "core protein" such as p-nitrophenyl-beta-D-xyloside suggested that synthesis of the core protein was rate limiting; SF and NF were equally facile in SO4-GAG chain synthesis in the presence of a beta-xyloside. SF appear to retain in vitro a partially activated state for many generations, at least with respect to hyaluronic acid synthesis.
Most glycosaminoglycans (GAGs) formed by lung fibroblasts under both basal and stimulated conditions were secreted into the culture medium. High molecular weight (greater than 10(6) daltons) hyaluronic acid (HA) was the major GAG species formed. Most of the SO4-GAG synthesized by lung fibroblasts was of proteoglycan (PG) monomer size. Agents stimulating complex carbohydrate formation also exhibited some selectivity with respect to whether HA or PG was formed in incremental amounts. Hyaluronate synthesis was especially stimulated by endotoxins, SO4-GAG by beta-xylosides, and PG by CTAP-III.
Connective tissue activating peptides (CTAPs) extracted from leukocytes and platelets stimulate glycolysis and synthesis of glycosaminoglycan and DNA in cultured human connective tissue cells. CTAP-III, isolated from fresh or outdated human platelets, is a low molecular weight single-chain protein with an isoelectric point of 8.5 that markedly stimulates DNA synthesis and multiple aspects of glycosaminoglycan and proteoglycan metabolism. This report presents a definitive comparison of CTAP-III prepared by two methods [one designated (A), alternative] with similar platelet proteins described by others, beta-thromboglobulin (beta-TG) and low-affinity platelet factor 4 (LA-PF-4). CTAP-III, CTAP-III(A), LA-PF-4, and beta-TG have common antigenic determinants documented by immunoprecipitation and radioimmunoassay. CTAP-III, CTAP-III(A), and LA-PF-4 are biologically active in that they stimulate DNA and glycosaminoglycan synthesis by human synovial cells; beta-TG is inactive. Carboxyl-terminal digestion gave identical terminal sequences for CTAP-III, CTAP-III(A), and beta-TG. Amino-terminal sequence data indicate that CTAP-III and CTAP-III(A) (also LA-PF-4) are identical and differ from beta-TG only by an additional amino-terminal tetrapeptide (Asn-Leu-Ala-Lys-). The biologically active molecule, CTAP-III, may be proteolytically converted to its inactive degradation product (beta-TG) in the course of platelet aging, platelet storage, release from the platelets, or initiation of biological activity.
Current evidence from in vitro studies draws attention to families of molecules able to stimulate replication of different classes of connective tissue cells and to stimulate the formation of some or all of the components of the extracellular matrix for which such cells are responsible. Some mediators are known to stimulate synthesis and release of enzymes with potential for degradation of the connective tissue matrix. A few of these mediators have been purified sufficiently to permit chemical characterization and immunologic measurement in man.
Substances known to enhance synthesis of glycosaminoglycans (GAG) in human synovial fibroblast cultures include "Connective Tissue Activating Peptides" (CTAP) isolated from certain organs, leukocytes and platelets as well as cyclic AMP and specific prostaglandins. This report shows that immunoglobulin G (IgG) isolated from 7 mammalian sources, including human, stimulated GAG production by human synovial cultures 3 to 18 fold. IgG generally did not stimulate DNA synthesis by human synovial fibroblasts as determined by [3H]-thymidine uptake. On a molar basis, IgG had a specific activity similar to that of CTAP-Ib(spleen) and CTAP-III (platelets). Normal human plasma levels of IgG may be sufficient to provide additional stimulus for activation of synovial connective tissue during the inflammatory response.
Explore the source record for details and available documents.
Plasma levels of the CTAP-III antigen were measured by radioimmunoassay in 80 patients with rheumatic diseases. Patients with clear evidence of vasculitis usually exhibited increased plasma CTAP-III antigen. In both systemic lupus erythematosus and rheumatoid arthritis, there appeared to be a correlation between pCTAP-III values and other laboratory and clinical parameters of disease activity.