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Biomedical subjects

B Osterud

Publications and source records attributed to B Osterud.

143 records · Page 8Linked to original sources
PubMed1975

The activation of human factor IX.

The activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IXa had an apparent molecular wight of about 42-45000 in sodium dodecyl sulphate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions, wherease Ca2+-in and factor VII or Russell's-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

Calcium↗
PubMed1975

Purification and some characteristics of the coagulation factor IX from human plasma.

Non-activated coagulation factor IX was purified approx. 10,000-fold from human plasma. The final product was electrophoretically homogeneous and comprised a tingle polypeptide chain with a molecular weight of about 70,000 and a pI of 4.3-4.45. The N-terminal amino acid was glycine. The amino acid and the carbohydrate contents were analysed and a monospecific antiserum to the factor was raised in rabbits.

Amino Acids↗
PubMed1975

The interaction of the protein and phospholipid components of tissue thromboplastin (factor III) with the factors VII and X.

The protein and phospholipid components of tissue thromboplastin have been isolated and their interactions with factor VII and factor Xa have been studied by gel filtration, centrifugation and heat inactivation. As expected, the phospholipid fraction bound both factors in the presence of Ca2+. No evidence for an interaction of apoprotein III with factor VII or Xa was obtained.

Apoproteins↗
PubMed1974

The localization of a vitamin K-induced modification in an N-terminal fragment of human prothrombin.

1. The N-terminal fragment (PF-I) split off from prothrombin during coagulation was purified to homogeneity from human serum. 2. The apparent molecular weight is 27000+/-2000 in sodium dodecyl sulphate-polyacrylamide-gel electrophoresis, whereas a value of about 19600 is obtained by calculation based on amino acid and carbohydrate analyses. The N-terminal sequence is an Ala-Asx bond. The fragment contains about 16% carbohydrate, binds phospholipids in the presence of Ca(2+) and is adsorbed to BaSO(4). The pK(a) of its BaSO(4)-binding group(s) is 3.1-3.5. 3. By CNBr cleavage of fragment PF-I two peptides (C-1 and C-2) were obtained with molecular weights of about 5900 (C-2) and 12400 (C-1) on the basis of amino acid and carbohydrate analyses. Only the smaller (N-terminal) peptide is adsorbed to BaSO(4) and, since the ability of the whole protein to bind to BaSO(4) is known to be absent in samples obtained from patients treated with vitamin K antagonists, this peptide probably contains the site of a modification to the structure of the protein which occurs during biosynthesis and depends on vitamin K. This peptide does not contain hexosamine or sialic acid.

Amino Acids↗
PubMed1973

Some characteristics of the Coagulation Factor Xa purified from human serum.

1. Coagulation Factor X was purified from human serum to apparent homogeneity in disc gel electrophoresis, sodium dodecyl sulphate-polacrylamide-gel electrophoresis, immunoelectrophoresis and analytical ultracentrifugation. The method used was a modification of that described by Gladhaug & Prydz (1970). 2. The method permits the isolation of an activated form of Factor X (Xa) which has a molecular weight of about 25000. 3. Factor Xa is a glycoprotein containing about 14% carbohydrate. A preliminary report of the amino acid composition is given.

Amino Acids↗
PubMed1972

Inhibition of the thrombin-fibrinogen reaction by a macromolecular factor from rat liver.

1. The supernatant obtained by centrifugation of a rat liver homogenate at 100000g for 1h contained a heat-labile macromolecular inhibitor of the thrombin-fibrinogen reaction. 2. The inhibitor was purified to electrophoretic homogeneity by repeated preparative polyacrylamide disc electrophoresis. Inhibition was observed with purified inhibitor equivalent to about 1mug of protein/ml. 3. The inhibitor had a pI of 3.50-3.75, a molecular weight (from sodium dodecyl sulphate-polyacrylamide-gel electrophoresis) of 72000+/-3000 and was inactivated by p-hydroxymercuribenzoate or 5,5'-dithiobis-(2-nitrobenzoic acid). 4. Kinetic studies revealed a non-competitive inhibition, with the inhibitor probably acting on the thrombin-fibrinogen complex.

Animals↗
PubMedDate not supplied

Quantitation of endotoxin in blood from patients with meningococcal disease using a limulus lysate test in combination with chromogenic substrate.

The levels of endotoxin in blood were determined using the Limulus lysate test in combination with a chromogenic substrate. Plasma was analyzed from four patients with fatal meningococcal septicaemia and from one patient who survived meningococcal meningitis. All septicaemia patients showed high levels of endotoxin in their blood during the early stage of their disease. In two of these patients, blood samples collected at intervals of two days revealed a gradual disappearance of measurable endotoxin from the circulation. The patient with meningitis had no clinical signs of circulatory deficiency or coagulopathy and was consistently negative for endotoxin using this test procedure. Pretreating the plasma with heat and alkali and combining the Limulus lysate test with a chromogenic substrate seem to provide a sensible method for the detection and quantitation of endotoxin in blood.

Adolescent↗
PubMedDate not supplied

The role of arachidonic acid release and lipoxygenase pathway in lipopolysaccharide-induced thromboplastin activity in monocytes.

Lipopolysaccharide (LPS) stimulation of human monocytes in heparinized whole blood in vitro as expressed by induced activity of thromboplastin, has been studied. An essential role of arachidonic acid (20:4) release was found. 2,4'-Dibromoacetophenone, a phospholipase A2 inhibitor, totally blocked the induced synthesis of thromboplastin activity. Furthermore, nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, had an effect on the LPS-induced thromboplastin synthesis which varied from no inhibition in individuals insensitive to LPS ('low responders'), up to 80% inhibition in the person with the highest response ('high responder') to LPS. Platelets were found to be partially responsible for this difference. Thus, monocytes from high responders cross-combined with platelets from low responders were much less prone to LPS stimulation than they were in the presence of high responder platelets. Intake of acetylsalicylic acid caused a 50% increment of LPS-induced thromboplastin synthesis, and this effect was mediated by platelets.

Acetophenones↗