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Biomedical subjects

D S Pepper

Publications and source records attributed to D S Pepper.

At least 91 records · Page 5Linked to original sources
PubMed1976

Chemotaxis for human monocytes by fibrinogen-derived peptides.

Chemotactic activity for human peripheral blood monocytes was generated by the action of thrombin on human fibrinogen, a reaction known to release low molecular fibrinopeptides. Supernatants prepared by incubating Contortrix venom with fibrinogen, which cleaves the B peptide, were also chemotactic, whereas no activity was present in supernatants from Arvin venom, which cleaves peptides A, AP and AY. Thus fibrinopeptide B was chemotactic for the monocyte in addition to the neutrophil, as previously reported. Monocyte chemotactic activity was also generated by the action of plasmin on human fibrinogen and shown to be associated with the D and E fragments but not with a mixture of fragments X and Y. When plasmin digestion was stopped at time intervals up to 24 h, monocyte chemotactic activity corresponded with the appearance of the D and E fragments. The monocyte chemotactic activity, contained in a 24 h digest, eluted from Sephadex G-75 at VO, corresponding to the expected position of the D and E fragments whereas neutrophil chemotactic activity eluted with molecules of molecular size of approximately 30 000 daltons. Thus fragments D and E derived from plasmin digestion of fibrinogen attract the monocyte whereas only the small uncharacterized peptides were chemotactic for the neutrophil. These different profiles of chemotactic activity for the neutrophil and the monocyte in terms of plasmin digestion products of fibrinogen may be of significance in the events leading to the accumulation of these cells in vivo during fibrin deposition.

Chemotaxis↗
PubMed1976

Three approaches to the radioimmunoassay of human beta-thromboglobulin.

Three radioimmunoassays for the measurement of beta-thromboglobulin are described. The standard method, using antiserum in solution, could be used to measure plasma concentrations of beta-thromboglobulin with the results available after 2-3 d. The use of a greater dilution of antiserum and tracer, with delayed addition of tracer, resulted in a more sensitive assay suitable for measuring b-thromboglobulin in urine. The use of a solid-couples antiserum under non-equilibrium conditions allowed the measurement of plasma levels of beta-thromboglobulin after an assay incubation time of 1 h. These three radioimmunoassay systems for beta-thromboglobulin cover the likely clinical requirements for the measurement of this platelet specific protein.

Beta-Globulins↗
PubMed1975

Further investigations on antithrombin III in the plasmas of patients with the abnormality of antithrombin III Budapest.

Antithrombin III (AT-III) was studied in a thrombophilic family with an abnormal AT-III molecule (antithrombin III Budapest) using a modified crossed immunoelectrophoresis technique, gel filtration, 'rocket' immunoelectrophoresis and a heparin cofactor assay. When agarose was applied in the first phase of the crossed immunoelectrophoresis, the normal and the pathological AT-III revealed identical electrophoretic mobility. However, when heparin was mixed with agarose in the first phase of electrophoresis, the propositus' plasma displayed a different AT-III pattern from normal plasma. His plasma contained the first component of the normal plasma (Immune Antithrombin III1, IAT-III) in a concentration of only 5% of normal, and a protein in high concentration which although immunoreactive to AT-III antisera, had an electrophoretic mobility similar (but not identical to that of IAT-III2. This abnormal protein had no heparin cofactor activity and a molecular size greater than normal plasma AT-III. Unlike AT-III, the addition of heparin did not change the molecular size of the pathogic AT-III molecule significantly. The abnormal protein was present in lower concentrations in the patient's children and at the time of study they had no clinical or laboratory evidence of intravascular coagulation.

Adult↗
PubMed1975

The isolation and characterisation of a platelet-specific beta-globulin (beta-thromboglobulin) and the detection of antiurokinase and antiplasmin released from thrombin-aggregated washed human platelets.

A protein fraction was isolated from the supernatant of thrombin-aggregated washed human platelets and was shown, by immunodiffusion techniques, to contain a platelet-specific beta-globulin (beta-thromboglobulin) as the major component. A molecular weight of 35 800 was determined for beta-thromboglobin from the measured sedimentation coefficient of3.0 S and Stokes radius of 2.85 nm. Beta-Thromboglobin was detected in the serum from whole blood and the supernatant of 48-h-old platelet-rich plasma and 28-day-old citrated whole blood, but not in platelet-poor plasma. The fraction containing beta-thromboglobulin was shown to possess an antiurokinase activity but was devoid of antiplasmin activity. A further fraction of approximate molecular weight 70 000 was also isolated which contained an antiplasmin but was devoid of antiurokinase activity.

Animals↗
PubMed1975

Platelet antiheparin activity. The isolation and characterisation of platelet factor 4 released from thrombin-aggregated washed human platelets and its dissociation into subunits and the isolation of membrane-bound antiheparin activity.

Platelet factor 4 was isolated by gel filtration from the soluble release products of thrombin-aggregated washed human platelets as a proteoglycan-platelet factor 4 complex of molecular weight 358 000, Stokes radius (r-s) of 14.0 nm, sedimentation coefficient (s) of 7.1 S and frictional ratio (f/f-o) of 3.04. The complex was dissociated at high ionic strength (I equals 0.75) and the proteoglycan separated from platelet factor 4 by gel filtration. Platelet factor 4 had a molecular weight of 27 100, r-s of 2.52 nm, s of 2.4 S and f/f-o of 1.26, was insoluble under physiological conditions but readily soluble at pH 3. Under these conditions platelet factor 4 dissociated into four subunits with a molecular weight of 6900, r-s of 1.92 nm, s of 0.8 S, and f/f-o of 1.52. Qualitative N-terminal amino acid analysis showed the presence of glutamic acid or glutamine as the major end group. Platelet factor 4 was compared with protamine sulphate, which has similar biological properties, by electrophoresis at pH 2.2, in which both migrated as single bands but with differing mobility, and by amino acid analysis which showed a more normal distribution of residues than occurred in protamine sulphate. Of the basic amino acids platelet factor 4 (molecular weight 27 100) contained 5.97% arginine, 3.18% histidine, and 12.31% lysine compared to protamine sulphate with 64.2% arginine, 0.6% lysine and no histidine. A partial specific volume (v) of 0.747 was calculated for platelet factor 4 from its amino acid analysis. A membrane fraction with antiheparin activity, an isopycnic density of 1.090-1.110 and r-s of 15-35 nm, was also isolated by sucrose density gradient centrifugation from the ultrasonicated insoluble platelet residue remaining after thrombin-induced aggregation of washed human platelets. Trypsin treatment of the membrane fraction neither solubilised nor destroyed the activity.

Amino Acid Sequence↗
PubMed1975

Investigations on antithrombin III in normal plasma and serum.

Studies on antithrombin III (AT-III) were made by a modification of the two dimensional crossed immunoelectrophoresis technique and gel filtration. Mixing various quantities of heparin with agarose in the first phase of electrophoresis, AT-III from normal human plasma and serum revealed a heterogeneity which depended on the heparin concentration in the agarose gel. At heparin concentrations higher than 16 u/ml, AT-III displayed three components with different electrophoretic mobilities. The component with the highest mobility (designated immunoantithrombin III1 : IAT-III1) dominated in plasma. In normal serum, however, the quantity of this component was decreased and the two other peaks with a slower electrophoretic mobility (IAT-III2 and IAT-III3) became more evident. Normal human plasma and serum were filtered on Sephadex G-200 and the AT-III concentration measured in the fractions by rocket immunoelectrophoresis. The peaks of AT-111 were found in the same fractions for both plasma and serum and were coincident with the albumin peak of the plasma proteins. However, in the case of serum the AT-III concentration decreased less sharply in those fractions with higher molecular weight than in the corresponding plasma fractions. Analysis of these fractions by crossed immunoelectrophoresis revealed that the two components with slower electrophoretic mobility (IAT-III2 and IAT-III3) had higher molecular size than IAT-III1, that the concentration of IAT-III2 and IAT-III3 was significantly higher in serum, and that the high molecular weight components in plasma and serum were qualitatively identical. It is concluded that high molecular weight complexes between AT-III and activated coagulation factors may be present in normally circulating blood and that their detection and possibly quantitation can be achieved using the heparin/agarose crossed immunoelectrophoresis system.

Antithrombin III↗