Pharmacokinetic and biological activities of dermatan sulfate (Mediolanum MF701) in healthy human volunteers.
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Adult↗
Biomedical subjects
D S Pepper
Publications and source records attributed to D S Pepper.
Quantitation of expression of idiotopes recognized by a panel of monoclonal antibodies in normal serum immunoglobulin: use of a novel 4-stage ELISA assay.
This paper describes the application of a sensitive ELISA assay detecting as little as 10 ng/ml of a specific idiotope. Using this assay we were able to divide monoclonal anti-idiotypic antibodies generated using a single IgG1 lambda paraprotein as the immunogen into three distinct groups. Seven antibodies detected determinants which were expressed only by the immunogen. The remaining seven antibodies all reacted with normal serum immunoglobulin. Four antibodies reacted with "public" idiotopes which were strongly expressed by serum immunoglobulin, and three antibodies reacted with "restricted public" idiotopes which were only weakly expressed by serum immunoglobulin. This last group may be of significant interest as agents for the immunotherapy of B-cell malignancies. The conservation of expression of these idiotopes in many individual sera suggests that they have a physiological role in immune regulation and would therefore be excellent targets for immunotherapy of B-cell tumours while their quantitatively low expression by circulating immunoglobulin is unlikely to interfere with tumour cell specific binding in vivo.
Animals↗
Rubber glove hygiene.
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Gloves, Surgical↗
Immunoaffinity purification of factor VIII complex.
Murine monoclonal antibodies to human von Willebrand factor (vWf) were immobilised on Sephacryl S-1000. Various solutes were screened for their ability to elute 125I-vWf from the immobilised antibodies. The most effective solutions were then tested to determine which allowed retention of factor VIII procoagulant activity (VIII:C) and activity of vWf measured by platelet aggregation in the presence of ristocetin (Ristocetin cofactor activity R. cof.). Finally, F VIII complex was purified from both plasma and cryoprecipitate by immunoaffinity chromatography under the selected conditions. The product had a specific activity of 45 units of VIII:C per mg of protein and 60 units of R. cof. per mg representing a 4000-fold purification from plasma. The fibrinogen and fibronectin content were each less than 4% of the total protein with vWf accounting for 60% of the total protein in the final product. Multimer analysis of the product showed a similar pattern to normal plasma and contamination by murine monoclonal antibody was less than 300 ng per mg of protein. A novel product is thus obtained containing both clinically relevant VIII:C and R. cof. in a single vial whilst using only one specific monoclonal antibody.
Antibodies, Monoclonal↗
Absorption of heparin, LMW heparin and SP54 after subcutaneous injection, assessed by competitive binding assay.
Unfractionated heparin, pentosan polysulphate (SP54) and the low molecular weight heparins CY216 and CY222 were injected subcutaneously at a minimum of weekly intervals into 5 healthy volunteers. The dose was 75 mg in all cases. Concentrations of administered glycosaminoglycan in serial plasma samples and voidings of urine were measured using a competitive binding assay, and biological activity was assessed in plasma using APTT and anti-Xa clotting assays. There was wide individual variation in the absorption of unfractionated heparin as indicated both by the maximal plasma concentrations reached 2-3 h after injection and by the area under the concentration vs. time curve. The efficiency of absorption increased and the individual variation decreased with decreasing molecular weight of the administered glycosaminoglycan. Urinary excretion correlated with plasma concentration, and recovery in the urine also increased with decreasing molecular weight. Similar patterns of uptake and clearance were indicated by the APTT and competitive binding assays, but anti-Xa clotting activity could be detected in the plasma after clearance of the administered glycosaminoglycan.
Absorption↗
Reductive amination for solid-phase coupling of protein. A practical alternative to cyanogen bromide.
For coupling proteins to Sephacryl gels periodate oxidation of these gels was investigated as an alternative method to cyanogen bromide activation. Optimum conditions were studied with respect to periodate concentration, time of oxidation, pH and type of coupling buffer, concentration of protein, temperature and time of protein uptake, and protein leakage after coupling. The effects of sodium cyanoborohydride and ascorbic acid as reducing agents, and of manganese ions as a potential catalyst were investigated. Using the derived optimum conditions, stable solid-phased antibodies were produced in high yield and used to adsorb factor VIII from plasma. These gels were stable for many weeks, as was the intermediate oxidised gel. Reductive amination for coupling proteins to oxidised Sephacryl gels results in increased binding and lower leakage than is obtained with cyanogen bromide activated agarose.
Acrylic Resins↗
Structural and immunological comparison of human thrombospondins isolated from platelets and from culture supernatants of endothelial cells and fibroblasts. Evidence for a thrombospondin polymorphism.
Thrombospondin is a 450-kDa glycoprotein secreted by a variety of cells including endothelial cells, fibroblasts and platelets. The aim of this study was to compare the structural and immunological properties of human endothelial, fibroblast and platelet thrombospondins. All three thrombospondins were purified, digested with thermolysin, and the subsequent thermolysin-generated fragments isolated on a Superose 12 gel-permeation column using non-denaturating conditions. Each isolated proteolytic fragment of thrombospondins was then detected using either a radioimmunoassay with a polyclonal antibody or an enzyme-linked immunosorbent assay with three monoclonal antibodies (P10, MA-I, MA-II) directed against different epitopes of whole platelet thrombospondin. The fragmentation pattern of human endothelial thrombospondin consists of six major thermolysin-generated fragments (135-110, 98-82, 54-47, 25-20, 18-15 and 10 kDa) having molecular masses very similar to those observed with human fibroblast thrombospondin (115-100, 92-80, 54-49, 27-21, 17-13 and 12-10 kDa). Treatment of platelet thrombospondin with thermolysin only generated four proteolytic fragments having molecular masses of 110, 50, 25 and 12/10 kDa respectively. All these proteolytic fragments of endothelial, fibroblast and platelet thrombospondins were recognized by a polyclonal antibody. Monoclonal antibodies MA-I and P10 essentially recognized two proteolytic fragments (135-110, 98-82 kDa) of endothelial and fibroblast (115-100, 92-80 kDa) thrombospondins, and the 110-kDa fragment of platelet thrombospondin. Monoclonal antibody MA-II recognized three proteolytic fragments (54-47, 25-20, 18-15 kDa) of endothelial and fibroblast (54-49, 27-21, 17-13 kDa) thrombospondins, and two fragments (50, 25 kDa) of platelet thrombospondin, different from those detected by P10 an MA-I. The results clearly demonstrate that, under non-denaturating conditions, endothelial and fibroblast thrombospondins are structurally different from platelet thrombospondin since two fragments of endothelial thrombospondin (98-82, 18-15 kDa), equivalent to those of fibroblast thrombospondin (92-80, 17-13 kDa), are not released from platelet thrombospondin after thermolysin treatment. These three forms of thrombospondin are, however, immunologically indistinguishable. To investigate further the structural differences observed between platelet and the two other forms of thrombospondin, their degree of polymerization was compared. Prior to thermolysin treatment, the three forms of thrombospondin were separated into several oligomers ranging from 450 kDa to 3300 kDa when injected onto a Superose 6 gel-permeation column.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Tandem purification of mouse IgM monoclonal antibodies produced in vitro using anion-exchange and gel fast protein liquid chromatography.
A tandem chromatographic procedure was used to isolate rapidly mouse IgM monoclonal antibodies produced by cultivation of hybridomas in vitro. Hybridoma culture supernatants containing mouse IgM monoclonal antibodies were first chromatographed on an anion-exchange Mono Q column connected to a fast protein liquid chromatography system. This anion-exchange step offers the advantage of obtaining IgM antibodies in a concentrated form. The IgM-rich fractions from the Mono Q column were then injected on a gel filtration Superose 6 column equilibrated with a low-ionic strength buffer and eluted with a high-ionic strength buffer. Assessment of the purity of isolated IgM monoclonal antibodies was performed by sodium dodecyl sulphate polyacrylamide gel electrophoresis together with a Coomassie Brillant Blue R 250 staining technique. Assessment of the immunoreactivity of isolated IgM monoclonal antibodies was performed by an enzyme linked immunosorbent assay using a solid phase adsorbed antigen against which IgM monoclonal antibodies were directed. The chromatographic procedures described allows the rapid isolation of mouse IgM monoclonal antibodies produced in vitro at a high degree of purity and in an immunoreactive state.
Animals↗
Low-resolution structure of the complex of human blood platelet factor 4 with heparin determined by small-angle neutron scattering.
Small-angle neutron scattering was used to confirm that human platelet factor 4 was a compact tetrameric globular protein of radius of gyration 1.74 nm and indistinguishable from a sphere. The same technique, when applied to the 1:1 mol/mol complex of platelet factor and heparin of Mr 14000, revealed that the radius of gyration of the particle varied, depending on the relative proportion of 2H2O to H2O in the solvent. Analysis of this variation by the method of Ibel and Stuhrmann (Ibel, K. and Stuhrmann, H.B. (1975) J. Mol. Biol. 93, 255-266) revealed that in the complex the material of greatest neutron-scattering length (the highly sulphated polysaccharide heparin) was furthest from the centre of the particle. This confirms the postulate of Luscombe and Holbrook (Luscombe, M. and Holbrook, J.J. (1983) in Glycoconjugates (Chester, A.M., Heinegård, D., Lundblad, A. and Svensson, S., eds.), pp. 818-819, Secretariat, Lund) that the exact 1:1 mole ratio of heparin (Mr greater than 10 000) to platelet factor in this stable complex arises from the heparin winding around the outside of a globular protein core.
Heparin↗
The production and characterisation of a panel of ten murine monoclonal antibodies to human procoagulant factor VIII.
A panel of 10 murine monoclonal antibodies to procoagulant FVIII has been developed from the fusion of a single spleen. Balb/c mice were injected with a purified preparation of FVIII: Ag, and antibody production in sera and hybrid culture supernatants was monitored using a specific radiometric screening assay. The antibodies all inhibit FVIII clotting activity in normal plasma, and when immobilised on agarose retain their ability to recognise and bind the FVIII procoagulant protein. Studies on protein A-purified immunoglobulins demonstrate a range of properties within the panel of antibodies with regard to species cross-reactivity, clotting inhibition and immunoadsorption. The panel of antibodies has been used to screen heat-treated FVIII concentrates for the occurrence of heat-induced neoantigens.
Animals↗
The use of human endothelial cells cultured in flat wells and on microcarrier beads to assess tissue plasminogen activator and factor VIII related antigen release.
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Antigens↗
Structural and immunological differences between human platelet and endothelial thrombospondins.
The structural and immunological properties of human thrombospondins isolated from platelets and from endothelial cells were compared. Both thrombospondins were digested with either trypsin or thermolysin, in the presence or absence of calcium, then injected onto a Superose 12 gel filtration column. The isolated thermolysin-generated fragments of thrombospondins were identified by radioimmunoassays using either different monoclonal antibodies or a polyclonal antibody directed against platelet thrombospondin. The results show that platelet and endothelial thrombospondins are both partially protected from trypsin digestion in the presence of calcium but have different trypsin and thermolysin fragmentation patterns. The thermolysin-generated fragments from platelet and endothelial thrombospondins are recognized differently by a monoclonal antibody whereas all of them are identified by a polyclonal antibody.
Antibodies, Monoclonal↗
The measurement of heparin and other therapeutic sulphated polysaccharides in plasma, serum and urine.
The competitive binding assay described will specifically and accurately measure concentrations of administered heparin in biological fluids with a sensitivity of 60 ng ml-1. Neither endogenous glycosaminoglycans, nor plasma proteins such as ATIII and PF4 interfere in the assay. Semi-synthetic highly sulphated heparinoids and LMW heparin can also be measured. Using this assay heparin clearance followed simple first-order kinetics over the dose range 100-5,000 units, but the half-life was strongly dose-dependent. There was good correlation with heparin activity measurements by APTT and anti-Xa clotting assays. Plasma concentrations were measurable for at least 5 h following subcutaneous injection of 10,000 units of heparin. Excretion in the urine could be followed after all but the lowest intravenous dose. This assay, used in conjunction with measurements of heparin anticoagulant activity, will be valuable in the elucidation of mechanisms of action of heparin and the heparinoids, and in the assessment and management of problems related to heparin therapy.
Antithrombin III↗
Metabolism of sodium pentosan polysulphate in man measured by a new competitive binding assay for sulphated polysaccharides--comparison with effects upon anticoagulant activity, lipolysis and platelet alpha-granule proteins.
Three human volunteers were injected with a range of doses of pentosan polysulphate, SP54, i.v. or s.c. A competitive binding assay (CBA) for sulphated polysaccharides was used to detect circulating SP54 after doses as low as 1 mg i.v. and a linear relationship was observed between the peak plasma concentration of SP54 measured by CBA and the administered dose. A comparison was made between the clearance of SP54 measured by CBA and its anticoagulant and lipolytic activities. SP54 was detectable by CBA after doses which caused no alteration in activated partial thromboplastin time (APTT) or anti-factor Xa activity but after which a small increase of lipase activity was measurable. After SP54 at 10 mg i.v. or 100 mg s.c. anti-factor Xa activity was 4-6 times greater than would be expected from the in vitro activity of the concentrations of SP54 measured by CBA. Like heparin and other heparin analogues, SP54 caused an increase in plasma concentrations of platelet factor 4 (PF4) without a concomitant rise in beta-thromboglobulin (beta-TG). It is concluded that the newly developed CBA will provide a more sensitive means than conventional bioassays for the determination of plasma concentrations of SP54.
Adult↗
Characterisation of epitopes on human tissue plasminogen activator recognised by a group of monoclonal antibodies.
Seven mouse monoclonal antibodies have been produced against human melanoma tissue plasminogen activator (t-PA). They were specifically bound to 125I t-PA but not 125I urokinase (u-PA) and inhibited t-PA, but not u-PA, activity in plasminogen-rich 125I fibrin wells. Three of the antibodies directly inhibited the amidolytic activity of t-PA and the two most effective also bound near the active site histidine residue as determined by competition experiments using active site blocking agents. Several antibodies interfered with the fibrin binding properties of t-PA. One antibody neither interacted with the active site nor inhibited fibrin binding but still effectively quenched t-PA activity in fibrin wells suggesting that it masks another region of the molecule necessary for effective biological activity.
Animals↗
Quantitation by radioimmunoassay of thrombospondin synthesised and secreted by human endothelial cells.
Synthesis and secretion of thrombospondin by cultured human endothelial cells was quantified using a sensitive radioimmunoassay. Two endothelial lines were examined; those from umbilical veins and those from saphenous veins. The foetal line secreted approximately 17 micrograms/10(6) cells of the antigen at 24 hr, whereas the saphenous line secreted five times less in the same period. Intracellular values were similar in both lines. Thrombin and calcium ionophore A23187 were added to umbilical vein endothelial cultures. In contrast to platelets where both agents cause a rapid release reaction, no such thrombospondin release was observed in endothelial cells.
Calcimycin↗
Monoclonal antibodies directed against human alpha-thrombin and the thrombin-antithrombin III complex.
Human alpha-thrombin was poorly immunogenic in Balb/c mice. Nevertheless, following fusion of spleen cells from a responding mouse with NS-1 cells, 8 mouse monoclonal antibodies against alpha-thrombin were isolated, and 6 were characterised. Five of these were isotype IgG2a, and one was IgG1. One, EST 1, bound thrombin only minimally, and was directed against a neoantigen on the thrombin-ATIII (T-AT) complex. This antibody also recognised a site on prothrombin, though with much lower affinity. Its binding was markedly temperature-dependent, indicating a requirement for molecular mobility. A second antibody, EST 4, would not bind the T-AT complex. It inhibited both the clotting and amidase activities of thrombin, and modification of the active site histidine, but not the active site serine, reduced the affinity constant of binding to EST 4. This antibody appears to be directed against an epitope in the vicinity of the enzyme active site. The epitopes for EST 1 and EST 4 were both remote from those of the other monoclonal antibodies, EST 2, 6, 7 and 8. These four competed with each other for binding to thrombin, and all inhibited clotting but not amidase activity. Thrombin binding was not affected by modification of the active site, though formation of the T-AT complex reduced the affinity of binding to EST 6 and EST 8. These monoclonals recognise epitopes in the region of the fibrinogen binding site.
Animals↗
Metabolism of sodium pentosan polysulphate in man--catabolism of iodinated derivatives.
An iodinated derivative of the heparin analogue SP54 has been prepared and used in conjunction with unlabelled SP54 to study the catabolism and organ distribution of this potential antithrombotic agent in healthy human volunteers. As observed previously with 125I-heparin, we found that the 125I-SP54 was rapidly cleared from the circulation, returning later in a desulphated form. Organ distribution studies with 123I-SP54 suggested that the liver and spleen were major sites of desulphation. Gel filtration and Polybrene binding showed the presence of sulphated macromolecular SP54 and desulphated macromolecular and depolymerised SP54 in post-injection urines. No depolymerised material was present in plasma suggesting depolymerisation occurs in the kidney.
Adult↗