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Biomedical subjects

T Holm

Publications and source records attributed to T Holm.

At least 109 records · Page 6Linked to original sources
PubMed1976

The influence of ethanol feeding on the activities of factors II, VII, VIII, IX and X in rats.

The effect of chronic administration of ethanol to rats in a controlled regimen upon the activities of the coagulation factors II, VII, VIII, IX and X has been studied. No significant differences were found for factor II, IX and X between the ethanol-treated rats and the control group given an isocaloric diet with carbohydrate replacing ethanol. Factor VII activity was somewhat higher and factor VIII activity decreased significantly in the experimental group when ethanol treatment was combined with an approximately two-fold increase in dietary polyunsaturated fatty acid.

Animals↗
PubMed1976

The effect of phospholipase C on human blood platelets.

The effect of phospholipase C (EC 3.1.4.3) on human blood platelets has been studied. Phospholipase C from Bacillus cereus was purified to homogeneity as judged by analytical and sodium dodecyl sulphate disc gel electrophoresis and by immunoelectrophoresis. Human platelets isolated from platelet-rich plasma by gel filtration or by centrifugation and washing were incubated with phospholipase C. A loss of 20-45% of the total platelet phospholipid was observed, whereas 88% was hydrolyzed when platelet homogenates were submitted to identical enzyme treatment. Intact platelets lost 50-75% phosphatidylethanolamine, 20-50% phosphatidylcholine, and 20-25% phosphatidylserine. Sphingomyelin was not a substrate for the enzyme under the conditions used. The platelets contained no detectable endogenous phospholipase C activity. The loss of phospholipid was not accompanied by aggregation of the platelets, nor did the platelets lose their ability to aggregate with ADP or thrombin. Total platelet factor 3 releasable by freezing and thawing was reduced. Measurements of releasable platelet factor 4 and the efflux of serotonin showed that no release reaction was triggered even when up to 45% of the total phospholipid in the platelets was hydrolyzed. When sphingomyelinase was added together with, before, or after phospholipase C, aggregation occurred. Sphingomyelinase alone gave no aggregation. The gel-filtered platelets also aggregated upon addition of purified phospholipase C from Clostridium perfringens. The distribution of phospholipids in the platelet membrane is discussed.

Bacillus cereus↗
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↗