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Biomedical subjects

R J Flower

Publications and source records attributed to R J Flower.

At least 181 records · Page 10Linked to original sources
PubMed1983

Further characterization of the glucocorticoid-induced antiphospholipase protein "renocortin".

The steroid-induced anti-phospholipase protein "Renocortin" has been further characterized by column chromatography and a monoclonal antibody. In medium devoid of foetal calf serum, renomedullary insterstitial cells in culture exposed to the anti-inflammatory steroid dexamethasone released 3 peptides of apparent MW: 15k, 30k, and 45k possessing similar biological properties to "renocortin", "lipomodulin" and "macrocortin". A monoclonal antibody directed against macrocortin also bound the 45k peptide released from the renomedullary cells. The 15k species was, like macrocortin, inactive in an "in vitro" enzymatic assay but recovered its full inhibitory activity after dephosphorylation by alkaline phosphatase treatment. We conclude that "macrocortin", "lipomodulin" and "renocortin" are similar if not identical proteins. We propose a scheme to account for "in vivo" secretion and regulation of these proteins.

Animals↗
PubMed1982

Glucocorticoids induce the formation and release of anti-inflammatory and anti-phospholipase proteins into the peritoneal cavity of the rat.

1 Dexamethasone and hydrocortisone induced the release of anti-phospholipase proteins into the peritoneal cavities of rats. 2 Adrenocorticotrophic hormone (ACTH) also releases these proteins in normal but not in adrenalectomized rats. 3 Peritoneal lavage proteins were separated by ion-exchange and size exclusion chromatography. The anti-phospholipase activity occurred in four separate fractions with the major component having an apparent mol. wt. of 40 k. 4 Column fractions containing these anti-phospholipase proteins had anti-inflammatory effects in the rat carrageenin pleurisy model whereas other fractions were inactive. 5 The proteins appear to be identical to macrocortin and lipomodulin, the 'second messengers' of glucocorticoid hormone action on the arachidonate system.

Adrenocorticotropic Hormone↗
PubMed1981

Arachidonic acid 15-lipoxygenase from rabbit peritoneal polymorphonuclear leukocytes. Partial purification and properties.

Arachidonic acid 15-lipoxygenase was purified from rabbit peritoneal polymorphonuclear leukocytes. The enzyme was recovered in the cytosol fraction after sonication and purified about 250-fold by acetone precipitation, column chromatography on CM52, Sephadex G-150, and hydroxyapatite. The enzyme catalyzed the conversion of arachidonic acid to 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE), which then decomposed to a mixture of 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE), 15-keto-5,8,11,13-eicosatetraenoic acid, 13-hydroxy-14,15-epoxy-5,8,11-eicosatrienoic acid, and 11,14,15-trihydroxy-5,8,12-eicosatrienoic acid. The enzyme was specific for oxygenation at carbon 15 of arachidonic acid. The apparent molecular weight of the enzyme was about 61,000 as measured by Sephadex G-150 gel filtration chromatography. The enzyme was sensitive to sulfhydryl-blocking reagents such as p-chloromercuribenzoic acid. The enzyme activity was inhibited by eicosatetraynoic acid (ETYA) or 3-amino-1-(m-(trifluoromethyl)-phenyl)2-pyrazoline (BW755C), but not by indomethacin up to 200 micrograms/ml.

Animals↗
PubMed1981

Measuring platelet and leucocyte aggregation/adhesion responses in very small volumes of whole blood.

A technique is described by which leucocyte and platelet aggregation may be measured in 100 microliter (or less) of citrated whole blood. The blood is first diluted in a balanced salt solution and aggregation responses measured with an electronic aggregometer. Leucocytes may be aggregated with substances such as the chemotactic peptide f-met-leu-phe, and platelets with the conventional agents such as ADP or collagen. The response of the leucocytes to f-met-leu-phe is very sensitive to the inhibitory activity of mepacrine. The aggregation of platelets, but not leucocytes, is blocked by low concentrations of indomethacin. The technique is useful for drug screening, diagnostic purposes, ad investigating platelet and leucocyte pharmacology and physiology.

Animals↗
PubMed1981

The inhibition by hydrocortisone of prostaglandin biosynthesis in rat peritoneal leucocytes is correlated with intracellular macrocortin levels.

Hydrocortisone inhibits prostaglandin generation by rat peritoneal leucocytes by releasing the polypeptide phospholipase inhibitor, macrocortin. The susceptibility of these cells to hydrocortisone is directly correlated with their intracellular macrocortin content. Cells depleted of the peptide by prior incubation with steroid cannot respond to the steroid, until a fresh intracellular store has been synthesized. In vitro, this process requires 4-5 h. Cells remain sensitive to the inhibitory action of the peptide at all times.

Animals↗
PubMed1980

Macrocortin: a polypeptide causing the anti-phospholipase effect of glucocorticoids.

Anti-inflammatory glucocorticoids inhibit prostaglandin (PG) biosynthesis by preventing arachidonic acid release from phospholipids rather than inhibiting the cyclooxygenase. As in other cells, this steroid action depends on receptor occupation and de novo protein/RNA biosynthesis. We have previously shown in guinea pig perfused lungs and rat peritoneal leukocytes that the effect of steroids in PG generation is mediated by an uncharacterized 'second messenger'. Now, we report that this factor (which we have named 'macrocortin') is an intracellular polypeptide whose release and synthesis are stimulated by steroids. Macrocortin derived from rat peritoneal leukocytes is very similar to that released from guinea pig lungs.

Animals↗
PubMed1980

Regulation of pulmonary arachidonic acid metabolism by anti-inflammatory steroids.

Enzymes in cells from many tissues including the lung metabolize arachidonic acid to a variety of highly active local hormones such as prostaglandins and 'slow-reacting substances'. Many of these play a part in the inflammatory response which follows injury or trauma or, in the case of slow-reacting substance, asthmatic bronchoconstriction. Both non-steroidal and steroidal anti-inflammatory drugs inhibit the formation of some or all of these products. The non-steroidal drugs block prostaglandin formation but not the formation of products such as slow-reacting substances. The steroids block the formation of all products. Their mechanism of action, investigated in the guinea-pig perfused lung, involved inhibition of arachidonic acid liberation, probably by suppression of phospholipase activity. To achieve this steroids must first bind to receptors in lung tissue and initiate de novo RNA and protein synthesis. This culminates in the synthesis or secretion by some cells in the lung of a polypeptide of mol.wt. 10 000-15 000 with potent anti-phospholipase properties. The generation of this factor could partly explain why steroids are so effective in the treatment of many types of inflammatory disease, and in particular why they are so efficacious against asthma.

Animals↗
PubMed1980

The electronic aggregometer: a novel device for assessing platelet behavior in blood.

A novel device for measuring platelet aggregation has been devised. The technique, which depends upon changes in electrical impedance caused by platelet accretion onto electrodes, is suitable for measurements of aggregation in either platelet-rich plasma (PRP) or blood. In PRP both turbidometric and electronic techniques give very similar responses to collagen, thrombin, prostaglandin endoperoxides, ADP, and arachidonic acid, although the electronic aggregometer gives no "shape-change" information and was somewhat more sensitive. In whole blood all these stimuli gave similar dose-related responses to those seen in PRP. The new technique is very suitable for investigating platelet pharmacology, since the inhibitors of aggregation, such as indomethacin and prostacyclin, can be conveniently quantitated in blood by using this technique.

Adenosine Diphosphate↗
PubMed1980

On the preparation of highly purified slow reacting substance of anaphylaxis (SRS-A) from biological extracts.

1 Very highly purified (greater than 100,000 u/mg) slow reacting substance of anaphylaxis (SRS-A) has been prepared by reversed phase high pressure liquid chromatographic (HPLC) techniques. 2 High resolution liquid chromatography suggests that SRS-A may exist in at least three distinct forms which are possible tautomeric. 3 SRS-A collected by antigen challenge in vivo and by calcium ionophore-induced release in vitro are chromatographically indistinguishable. 4 Treatment of SRS-A with diazomethane but not sodium borohydride results in a loss of biological activity but treatment of the methyl ester with base results in a partial recovery of activity. 5 Highly purified SRS-A was examined by infrared and ultra-violet spectroscopy, and found to have a benzene-aromatic and probably an amino acid.

Animals↗