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Biomedical subjects

H Sievertsson

Publications and source records attributed to H Sievertsson.

At least 37 records · Page 2Linked to original sources
PubMed1975

The binding of insulin and somatomedin A to human placental membrane.

A particulate membrane fraction from human placental membrane was shown to be rich in binding sites not only for insulin but also for somatomedin A. The binding of the 125I-labelled peptide was time and temperature dependent. Degrading activity present in the membrane fraction was negligible at +4 degrees C. The Scatchard plot for insulin binding revealed two types of binding sites with an apparent high affinity constant of 3.8 times 108 M(-1) and with 5.4 times 10(-9) moles of binding sites per mg of membrane protein. The Scatchard analysis of somatomedin A revealed two classes of binding sites with an apparent high affinity constant of 2.7 times 107 M(-1) and with 1.9 times 10(-8) moles of binding sites per mg of membrane protein. In high concentrations insulin interfered with the specific binding sites for somatomedin A and vice versa. In comparison with insulin the somatomedin A preparation was one million times more potent in displacing labelled somatomedin A than in displacing labelled insulin from their respective binding sites. A radioreceptor assay utilizing particulate placental membrane and labelled somatomedin A purified on the membrane enabled the determination of somatomedin in unextracted serum. The mean values of somatomedin A in sera from patients with pituitary dwarfism and acromegaly were 0.57 and 3.2 U/ml, respectively by radioreceptor assay and 0.41 and 1.61 U/ml, respectively by bioassay. Various causes of this discrepancy between the methods are discussed.

Acromegaly↗
PubMed1974

Effect of certain polypeptides on the biological activities of Measles virus.

The effect of a selected tripeptide, Z-d-Phe-Phe-Arg(NO(2)) (SV-4814) on the kinetics of lysis of green monkey erythrocytes by measles virus hemolysin suggested conditions of competitive inhibition. SV-4814 prevented not only hemoglobin release, but also the preceding leakage of K(+) through the cell membrane. The capacity of 12 different dipeptides, 6 tripeptides, including SV-4814, and 4 tetrapeptides to inhibit measles virus-specific hemolysis and infectivity was analyzed. Tri- and tetrapeptides were more active than dipeptides. The presence of aromatic amino acids and a free carboxyl terminal appeared to be a prerequisite for inhibitory activity. Two compounds, one tripeptide (Z-Phe-d-Phe-d-Tyr) and one tetrapeptide [Z-d-Phe-Arg(NO(2))-d-Met], carried an inhibitory activity, which was about two times higher than that of SV-4814.

Animals↗