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Biomedical subjects

H Prydz

Publications and source records attributed to H Prydz.

At least 181 records · Page 10Linked to original sources
PubMed1976

Parenteral administration of phospholipase C in the rat. Distribution, elimination, and lethal doses.

Infusions of tissue thromboplastin induce intravascular coagulation in animals. Phospholipase C (PLC) (EC 3.1.4.3) from Bacillus cereus has a marked protective effect against such infusions and might be of value in the therapy of certain types of intravascular coagulation. We have therefore studied the toxicity, half-life, and effect on lipolysis of purified PLC in rats, using parenteral administration of 14C-labelled enzyme. Following intravenous injection, the plasma half-life was 5.2-5.4 min, and LD50 was approximately 1.6-1.7 mg/kg. The effect of PLC on lipolysis was moderate. The enzyme does not appear to be bound to any plasma macromolecules, and there was no accumulation of labelled enzyme in tissues other than kidney.

Animals↗
PubMed1975

Studies on PIVKA-X.

The incorporation of 14C-glucosamine and 3H-leucine into PIVKA-X and factor X has been studied in Macaca mulatta by means of a monospecific precipitating antiserum. No difference in the incorporation into PIVKA-X and factor X was found. The half-lives of PIVKA-X and factor X were similar (about 30-35 h and 27-31 h respectively) indicating that the vitamin K-induced modifications did not alter the survival of protein. A Russell's-viper venom/cephalin test system for factor X was more sensitive to inhibition by PIVKA-X than was a tissue thromboplastin-based system.

Adsorption↗
PubMed1975

DNA synthesis in isolated HeLa cell nuclei. Optimalization of the system and characterization of the product.

DNA replication in isolated nuclei from synchronized HeLa cells has been studied in an effort to optimalize the system and characterize the product. The synthesis was highly dependent on the four deoxyribonucleoside triphosphates, ATP, and Mg2+. Optimum pH was about 7.8. The system was further stimulated by monovalent ions with NH4Cl and Tris-HCl (each 65 mM) being the most effective. The four ribonucleoside triphosphates and glycerol gave a slight but very reproducible and additive stimulation. Low concentrations of spermine and spermidine (0.2-1.5 X 10(-4) M) were also slightly stimulatory (10-15%) whereas higher concentrations were inhibitory. The reaction product was DNase sensitive, and banded at 1.699 g/ml in neutral CsCl together with bulk HeLa nuclear DNA. When studied by neutral CsCl and alkaline Cs2SO4 gradients, the incorporation of [3H]TTP was mainly (more than 85%) due to further elongation of strands initiated in vivo as evidenced by BrdUrd labeling.

Adenosine Triphosphate↗
PubMed1975

DNA synthesis in isolated HeLa cell nuclei. Evidence for in vitro initiation of synthesis of small pieces of DNA and their subsequent ligation.

Optimum conditions for a DNA synthesizing system based on isolated nuclei have been described (Krokan, H., Bjorklid, E., and Prydz, H. (1975), Biochemistry, preceding paper in this issue) [3H]TTP-labeled nascent DNA produced during very short pulses was analyzed by centrifugation in alkaline sucrose gradients. More than 80% of the radioactivity appeared in 2-4S pieces (primary DNA pieces). It would therefore seem that the synthesis of DNA is discontinuous both in the 5' leads to 3' and in the 3' leads to 5' directions. The size of the primary DNA pieces increases from 2-4 S up to 14 S with increasing pulse length. Evidence is presented that this increase is not caused by ligation between 2-4S primary pieces. Pulse-chase experiments showed that in this nuclear system primary pieces were ligated to a product generally larger than 30 S. Evidence is also given for the initiation of primary DNA pieces in vitro.

Cell Fractionation↗
PubMed1975

DNA synthesis in HeLa cell nuclei isolated in a non-aqueous medium.

Nuclei were isolated from synchronized HeLa cells in the S-phase by a modification of the non-aqueous method described by Kirsch et al. (Science (1970) 168, 1592-1595). The method involved lyophilization of the cells, homogenization in non-aqueous glycerol and centrifugation in a gradient of 0-35% (w/w) 3-chloro-1,2-propanediol in glycerol. Such nucleic incorporated deoxyribonucleotides into DNA when incubated in an aqueous buffer containing Mg2+, ATP, dATP, dGTP, dCTP and dTTP. The product was sensitive to DNAase and banded with bulk DNA in isopycnic centrifugation. Sedimentation of the product in alkaline sucrose gradients after labelling of the nuclei for 2 min revealed labelled material in the 5 S peak and in the 18 S area. The material in the 5 S peak moved into the 12 S area after a 13 min chase.

Cell Fractionation↗
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

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↗
PubMed1974

HeLa cell plasma membranes. I. 5'-Nucleotidase and ouabain-sensitive ATPase as markers for plasma membranes.

A method for the preparation of HeLa cell plasma membrane ghosts is described. The purity of the plasma membrane fraction was examined by phase contrast and electron microscopy, by chemical analysis, and by assay of marker enzymes. Data on the composition of the plasma membrane fraction are given. It was observed that the distribution pattern of 5'-nucleotidase activity among the subcellular fractions differed from that of ouabain-sensitive ATPase. In addition, the specific activity of 5'-nucleotidase did not follow the distribution of the membrane ghosts. Thus, this enzyme would seem unsuitable as a plasma membrane marker. A complete balance sheet for marker enzyme activities during the fractionation is necessary for the calculation of increase in specific activity because the activities of both 5'-nucleotidase and ouabain-sensitive ATPase might change during the fractionation procedures.

Adenosine Triphosphatases↗