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Biomedical subjects

S Hammarström

Publications and source records attributed to S Hammarström.

At least 181 records · Page 10Linked to original sources
PubMed1980

Enzymatic synthesis of 15-hydroperoxythromboxane A2 and 12-hydroperoxy-5,8,10-heptadecatrienoic acid.

Partially purified thromboxane synthase from human platelets converted prostaglandin G2 to two products. These were transformed to 12-hydroxy-5,8,10-heptadecatrienoic acid and thromboxane B2 by stannous chloride reduction and to 12-keto-5,8,10-heptadecatrienoic acid and 15-ketothromboxane B2 by lead tetraacetate dehydration. Trapping with methanol after short incubations of substrate with enzyme and reduction by stannous chloride yielded 11-O-methylthromboxane B2. Based on these results, the enzymatically formed products were identified as 12-hydroperoxy-5,8,10-heptadecatrienoic acid and 15-hydroperoxythromboxane A2.

Blood Platelets↗
PubMed1980

Nomenclature for leukotrienes.

A previously introduced nomenclature for leukotrienes is extended on the basis of the nature of the cysteine substituent and the total number of double bonds in new and earlier described compounds.

Animals↗
PubMed1980

Conversions of prostaglandin endoperoxides by prostacyclin synthase from pig aorta.

Partially purified prostacyclin synthase from pig aorta converted the prostaglandin (PG) endoperoxide PGH2 to prostacyclin (PGI2), and PGH1 to 12-hydroxy-8,10-heptadecadienoic acid (HHD). Both reactions were inhibited by 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HP) in a dose-dependent rashion. However, the reactions PGH2 leads to PGI2 and PGH1 leads to HHD appeared to differ: substrate availability was rate limiting in the latter reaction, while the enzyme became rapidly saturated witth PGH2 and a steady rate of prostacyclin formation was observed at higher substrate levels.

6-Ketoprostaglandin F1 alpha↗
PubMed1980

Endogenous synthesis of prostaglandins E1 and I2 in 3T3 fibroblasts transformed by polyoma virus. Effects on adenosine 3':5'-monophosphate production.

Prostaglandins (PG)E1, E2 and I2 were produced by polyoma virus transformed (py) 3T3 fibroblasts. The levels of PGE1, PGE2 and 6-keto-PGF1 alpha (degradation product of PGI2) were 22.7, 225 and 33.2 ng/ml medium, respectively, 72 h after medium change. The stimulatory potencies of exogenous PGE1, PGE2 and PGI2 on adenosine 3':5'-monophosphate (cyclic AMP) formation were similar. Therefore, the prostaglandin mediated increase in cyclic AMP levels observed during growth of these cells (Claesson, H.-E., Lindgren, J.A. and Hammarström, S. (1977) Eur. J. Biochem. 74, 13) is largely (greater than 80%) mediated by PGE2 and to lesser extents by PGE1 and PGI2.

8,11,14-Eicosatrienoic Acid↗
PubMed1980

Biological effects of 15-hydroperoxythromboxane A2 on platelets and aorta.

The conversion of PGG2 to 15-hydroperoxythromboxane A2 by purified thromboxane synthase from human platelets was recently reported (Hammarström, S. (1980) J. Biol. Chem.255, 518). The hydroperoxythromboxane is approximately 25 times more potent than PGG2 in causing aggregation of human platelet rich plasma and 30 times more potent than PGG2 as an inducer of contractions of rabbit aorta.

Animals↗
PubMed1980

Leukotriene D: a slow reacting substance from rat basophilic leukemia cells.

A slow reacting substance produced by rat basophilic leukemia cells, treated with ionophore A23187, was characterized by spectroscopic methods, enzymatic conversions, and chemical degradations as 5-hydroxy-6-S-cysteinylglycyl 7,9,11,14-eicosatetraenoic acid (leukotriene D). gamma-Glutamyltranspeptidase [gamma-glutamyltransferase; (5-glutamyl)-peptide: amino-acid 5-glutamyltransferase, EC 2.3.2.2] converted leukotriene C to a product identical to leukotriene D. This suggests that the stereochemistry of the arachidonyl moiety of leukotrienes C and D is the same [5(S)-6(R)-7,9-trans-11,14-cis]. Leukotriene D induces a faster contraction and, on a molar basis, is more potent than leukotriene C in the isolated guinea pig ileum bioassay.

Amino Acids↗
PubMed1980

Mitogenic responsiveness of human T-lymphocyte subpopulations: regulation by suppressive Fc-receptor-bearing T cells and influence of fractionation procedures.

The proliferative response induced by leucoagglutinin (La) in different subpopulations of human T lymphocytes was studied. Subpopulations enriched in cells with either high- or low-avidity receptors for sheep erythrocytes (SRBC) (EH +, EL +) were prepared by sequential E-rosetting. In addition, T lymphocytes prepared by E-rosetting under optimal conditions (E + TOT) were fractionated on wheat germ agglutin (WGA)-Sepharose columns, rendering fractions enriched in lymphocytes with either low- or high-avidity receptors for WGA. The T lymphocytes were found to comprise at least three functionally distinct subpopulations, differing with respect to mitogen responsiveness. Cells characterized by high-avidity receptors for WGA and SRBC were highly responsive to La stimulation, regardless of the method used for purification. In contrast, cells with low-avidity receptors for WGA and probably also for SRBC but lacking Fc receptors for IgG responded only marginally but were conditioned to respond when subjected to E-rosetting under optimal conditions. This response was suppressed by lymphocytes with Fc receptors for IgG, which probably also had low-avidity receptors for WGA and SRBC. The lymphocytes with high-avidity receptors for WGA ans SRBC did not appear to be susceptible to suppression by Fc gamma + cells.

Cell Separation↗
PubMed1980

Proliferative and cytolytic reactivities of human lymphocytes fractionated on wheat germ agglutinin-Sepharose columns before or after alloactivation in mixed lymphocyte culture.

Human T-lymphocyte preparations from peripheral blood with either high- or low-avidity receptors for wheat germ agglutinin (WGA) were obtained by fractioned on WGA--Sepharose columns. Both fractions contained progenitors of alloreactive T cells, proliferating in mixed lymphocyte culture (MLC) and acting as effector cells in cell-mediated lympholysis (CML). Proliferation and CML activity of the two fractions were equal and similar to those of the unfractionated cells. However, when the lymphocytes were fractionated after 5 days' MLC, most of the proliferating and cytolytic cells were found in the lymphocyte fraction enriched in cells with high-avidity receptors for WGA. The reactivity of the fractions was correlated to their content of blast-transformed cells. The binding of MLC-activated lymphocytes to WGA was specific, since it was inhibited by the competitive hapten D-GlcNAc and no cells were retained on control columns charged with human serum albumin-Sepharose. B cells and monocytic cells were enriched in the fraction with low-avidity receptors for WGA. As indicated by experiments in which cells were mixed in different proportions, the low MLC-CML activity of the lymphocytes in the fraction with low-avidity WGA receptors was not caused by suppressor cells present in that fraction.

Agglutinins↗
PubMed1980

On the mechanism of elevated prostaglandin E2 production in 3T3 fibroblasts transformed by polyoma virus.

Polyoma-virus-transformed 3T3 fibroblasts (py 3T3 cells) produce considerably more prostaglandin E2 than regular 3T3 cells during growth in cell culture. Incubations with exogenous arachidonic acid showed no increase in prostaglandin-producing capacity in the transformed cells. The rates of degradation of prostaglandin E2 were similar in the two lines. After labeling of cells with [1-14C]arachidonic acid, py 3T3 cultures continuously released radioactivity while the release by regular 3T3 cells was almost completed after 3 h. Prostaglandin E2 production during short incubations in buffer at various times after medium change was constantly higher in the transformed cells. Furthermore, hydrocortisone completely inhibited prostaglandin synthesis by the transformed cells. These results suggest that the increased formation of prostaglandin by py 3T3 cells is due to continuously elevated activity of phospholipase A2 or another acyl hydrolase.

Animals↗
PubMed1980

Molecular weight of detergent-solubilized prostaglandin-F2 alpha receptor from bovine corpora lutea.

A prostaglandin F2 alpha receptor localized in plasma membranes of bovine corpus luteum cells was solubilized by treatment with Triton X-100. Sepharose chromatographies of ([3H]prostaglandin F2 alpha)-receptor complex gave a Stokes' radius of 630 nm. In the absence of detergent, aggregated forms of the receptor appeared. Sedimentation experiments of solubilized receptor in sucrose/H2O and sucrose/2H2O density gradients gave the following values: sedimentation coefficient (S20, w) 4.6 S; partial specific volume (VB) 0.78 cm3/g and frictional ratio (f/fo) 1.6. Based on the sedimentation coefficient and the Stokes' radius and assuming that the receptor is a non-glycosylated protein the molar mass of the receptor-(Triton X-100) complex was 144000 g/mol. The VB value indicated that ca. 26% of the weight represented bound detergent and that the molecular weight of the prostaglandin F2 alpha receptor is approximately 107000.

Animals↗
PubMed1980

Identification of leukotriene C-1 as a major component of slow-reacting substance from rat mononuclear cells.

Slow-reacting substance (SRS) was produced by rat peritoneal mononuclear cells after stimulation with the ionophore A23187. The SRS consisted of two main components as judged by high-pressure liquid chromatography (HPLC) on Florisil. The larger and more polar component consisted mainly of leukotriene (LT) C-1 as judged by ultraviolet spectroscopy, mass spectrometry (after desulfurization), amino acid analysis, and conversion by soybean lipoxygenase. Comparisons with authentic LTC-1 showed identity on reverse phase HPLC and guinea pig ileum bioassay. The latter methods are known to distinguish between LTC-1 and stereoisomers of LTC-1.

Amino Acids↗