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Biomedical subjects

F Brosstad

Publications and source records attributed to F Brosstad.

At least 127 records · Page 7Linked to original sources
PubMed1982

Further studies on the interaction between thrombin and GP Ib using crossed immunoelectrophoresis. Effect of thrombin inhibitors.

The platelet surface protein GP Ib (glycocalicin-related protein) has been shown to be retarded by thrombin-Sepharose 4B in a crossed immunoelectrophoresis system. The interaction between GP Ib and thrombin was abolished when thrombin was blocked either at the active serine site with tosyl-lysine-chloromethyl-ketone (TLCK) or phenylmethylsulfonylfluoride (PMSF) or at the fibrinogen binding site (macromolecular binding site) with N-bromosuccinimide (NBS) or heparin, indicating that both sites have to be freely accessible for the retention of the glycocalicin-related protein by thrombin.

Animals↗
PubMed1982

Effects of thrombin on the integrity of monolayers of cultured human endothelial cells.

51Cr-prelabelled endothelial cells (EC) in confluent monolayers were incubated in RPMI 1640 + foetal calf serum 20% (v/v) to which purified thrombin was added. Thrombin (greater than or equal to 0.1 NIH U/ml) significantly accelerated 51Cr-release and caused extensive but reversible cell "contraction". Thrombin-exposed EC reacted to a new dose of thrombin with no appreciable shape change, but 51Cr-efflux was again accelerated. EC exposed to thrombin pretreated with N-bromosuccinimide (modifying the macromolecular site) or phenylmethylsulfonyl fluoride (blocking the serine site) retained normal morphology and did not leak excess amounts of 51Cr. Antithrombin III also inhibited the effect of thrombin. Pretreatment of EC with either indomethacin, aspirin, sulfinpyrazone, pronase or neuraminidase did not influence the effect of subsequent thrombin exposure.

Animals↗
PubMed1982

Demonstration of variable forms of the platelet factor 4 immunoprecipitate using crossed immunoelectrophoresis.

Proteins with different electrophoretic properties were precipitated by a monospecific antiserum to platelet factor 4 either as a "line" or as a "peak" precipitate. The "line" form seen on crossed immunoelectrophoresis of whole platelets was retained when immobilized thrombin was included in the intermediate gel. The retention was partially abolished when thrombin had been blocked at the active serine site or at the fibrinogen binding site. The "peak" form seen on analysis of material secreted from platelets passed unaffected through thrombin-Sepharose. It is suggested that platelet factor 4 exists in the platelets in a state different from that observed extracellularly after platelet secretion.

Antigens↗
PubMed1981

Crossed immunoelectrophoresis using immobilized thrombin in intermediate gel. A method for demonstration of thrombin-binding platelet proteins.

A method is described in which the interaction between thrombin and platelet proteins can be studied directly. Solubilized platelet proteins were examined by crossed immunoelectrophoresis against polyspecific antiplatelet antibodies, and the interaction with thrombin observed by insertion of an intermediate gel containing thrombin coupled to Sepharose 4-B. Four immunoprecipitates were absent or showed an altered position compared to that of the control containing regular Sepharose 4-B in the intermediate gel. These were No. 1 (representing platelet factor 4), No. 13 (glycocalicin-related protein, probably GP lb), No. 19 (factor XIII), and No. 2a which has not yet been identified. Immunoprecipitates No. 16, representing a complex of GP IIb and GP IIIa, and No. 6 (albumin) as well as the other immunoprecipitates seen in the control pattern were unaffected by the presence of immobilized thrombin in the intermediate gel. The interaction of glycocalicin-related protein as well as purified glycocalicin with thrombin was confirmed by use of a monospecific antiserum. It is concluded that crossed immunoelectrophoresis using immobilized thrombin in an intermediate gel represents a new and useful approach to the investigation of the interaction between thrombin and platelet proteins. This procedure may also be extended to many other interactions between agents and cell proteins.

Blood Platelets↗
PubMed1980

The normal range of osmotic fragility of red blood cells.

With the technique of Parpart et al (1947), the normal range for osmotic fragility of red blood cells had been estimated to include 5%--45% haemolysis at a salt concentration corresponding to 4.5 g NaCl/l (Dacie 1954). This estimate may be questioned, however. Thus, nearly 20% of the data obtained from 50 presumably healthy subjects fell outside these limits. Furthermore, the distribution pattern was very asymmetric with erroneously small standard deviation. On the other had, if the technical conditions (salt concentration, buffer) were properly adjusted, nearly all the observations were located with the straight part of the s-shaped haemolysis curve and scattered symmetrically around the mean. Under these conditions, the normal range (mean +/- 2 SD) included 22%--88% haemolysis. Moreover, this wider range included about 95% of the observations, even adapted to the original experimental situation. The present estimates should therefore replace earlier statements in the literature.

Adult↗
PubMed1978

Three new cases of an inborn qualitative fibrinogen defect (fibrinogen Oslo II).

An autosomally inherited, qualitative fibrinogen defect is presented. It is associated with prolonged thrombin clotting time, low plasma fibrinogen when assayed by a fibrin polymerization test and large amounts of fibrinogen antigen determinants in the supernatant after clotting. The plasma fibrinogen level was normal when assayed by an immunological technique or by quantitation of insoluble fibrin under conditions in which fibrin polymerization in enhanced. As judged from N-terminal amino acid analyses, fibrinopeptides were split off at normal speed, and the subunit chains of the fibrinogen appeared normal when examined on polyacrylamide gels. The abnormality was not associated with bleeding tendency, and other routine coagulation tests gave normal results. The findings are in accordance with the concept of defective fibrin polymerization.

Adult↗
PubMed1978

Platelet and fibrin(ogen) deposition in the artificial kidney. The influence of haematocrit, fibrin monomer and platelet inhibitors. An in vitro study.

The effect of variations in haematocrit (hct) on the retention of 51Cr-labelled platelets and 125I-labelled fibrinogen from normal, heparinized, human blood, circulated in an experimental "mini-Kiil" dialyzing system, was studied. Platelet retention (PR) on dialysis membranes and blood lines was found to increase with increasing hct. When only platelet rich plasma was circulated, a significantly lower PR was noted on the blood lines. Fibrin(ogen) deposition on the same surfaces showed a similar tendency. When 125I-labelled fibrin monomer was added to normal blood, prior to dialysis, fibrin deposition on the membranes and blood lines was of a much higher degree than in the control. However, PR was not significantly influenced by the presence or deposition of the fibrin monomer. Reduced platelet function, caused by incubation with acetylsalicylic acid prior to dialysis, led to less PR on the blood lines, but not on the membranes. The observed difference was, however, not statistically significant (p = 0.06). Pretreatment of platelets with prostaglandin E1, however, was able to reduce PR significantly both on dialysis membranes and blood lines.

Aspirin↗