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C N Berry

Publications and source records attributed to C N Berry.

29 records · Page 2Linked to original sources
PubMed1986

Identification of 6-oxo-prostaglandin E1 as a naturally occurring prostanoid generated by rat lung.

The spontaneous release of prostanoids from rat isolated perfused lungs was studied after acid/organic extraction of perfusates by bioassay, radioimmunoassay, thin layer and high performance liquid chromatographic methods and by gas chromatography-negative ion mass spectroscopy (g.c.n.i.m.s.). An acid/organic extractable anti-aggregatory vasodilator prostaglandin which inhibited the twitch response of the field-stimulated guinea-pig vas deferens was released from the Krebs-perfused rat lung in nanogram amounts similar to those of other detected prostanoids. Parallel biological assay suggested that this prostaglandin had very closely similar pharmacological activity to authentic 6-oxo-prostaglandin E1 (6-oxo-PGE1), a metabolite of prostacyclin (PGI2) generated by the action of the enzyme 9-hydroxyprostaglandin dehydrogenase (9-PGDH). 6-oxo-PGE1 was identified conclusively in extracts of rat lung perfusate by thin layer chromatography, high performance liquid chromatography and g.c./m.s. combined with bioassay (inhibition of platelet aggregation), and its covalent structure was defined by g.c. negative ion chemical ionization mass spectroscopy. The rank order of spontaneous release of prostanoids (measured by radioimmunoassay) from the perfused rat lung was 6-oxo-PGF1 alpha greater than thromboxane B2 (TXB2) greater than PGE2 greater than 6-oxo-PGE1 (measured biologically) greater than PGF2 alpha. Release of all five prostanoids was inhibited by indomethacin, but only that of 6-oxo-PGE1 was inhibited by naringenin. Rat lung 100,000 g cytosolic supernatants contained 9-PGDH activity capable of removing 9 beta-tritium from labelled prostacyclin and forming an acid/organic extractable 6-oxo-PGE1-like anti-aggregatory substance. This 9-PGDH activity was inhibited by naringenin (IC50 10.3 microM). 6 The relevance of these findings to the possible physiological role of 6-oxo-PGE1 in the lung is discussed, and we propose that 6-oxo-PGE, should be accorded the status ofa physiologically relevant, naturally occurring metabolite of arachidonic acid.

Alprostadil↗
PubMed1985

Age-dependent changes in the synthesis and catabolism of 6 oxo PGE1 and other prostanoids by the rat kidney in vitro.

Synthesis and catabolism of 6 oxo PGE1 was assessed in 100,000 g cell-free supernatant fractions of kidneys obtained from rats aged 20, 34 and 70 days. In addition the release of PGI2, TxA2 (measured as 6 oxo PGF1 alpha and TxB2, respectively), PGE2 and PGF2 alpha from kidney slices prepared from these three groups of rats was determined using specific radioimmunoassays. The conversion of PGI2 to 6 oxo PGE1 (but not 13,14 dihydro 15 oxo PGF2 alpha to 13,14 dihydro 15 oxo PGE2) was detected in supernatant fractions of kidneys from 20 day rats. Slices prepared from the kidneys of these animals spontaneously released significant amounts of three prostanoids (6 oxo PGF1 alpha greater than PGE2 greater than PGF2 alpha greater than TxB2 = 0). No formation of 6 oxo PGE1 from exogenous PGI2 was demonstrated in renal 100,000 g supernates from 34 and 70 day rats even though these supernates avidly oxidised 13,14 dihydro 15 oxo PGF2 alpha to 13,14 dihydro 15 oxo PGE2. In these animals the rank order of prostanoid release from kidney slices was PGE2 greater than 6 oxo PGF1 alpha greater than PGF2 alpha greater than TxB2 = 0. The catabolism of 6 oxo PGE1 is also age-dependent. In 20 and 34 day old rats 6 oxo PGE1 and PGE1 incubated with renal 100,000 g supernates undergo loss of biological activity as determined by the ability to inhibit ADP induced human platelet aggregation. In contrast, kidney 100,000 g supernates prepared from 70 day rats convert 6 oxo PGE1 to an unidentified metabolite with more potent anti-aggregatory activity. The possibility that 6 oxo PGE1 has a biological role in the developing rat kidney is discussed.

Age Factors↗
PubMed1985

Highly potent inhibition of prostaglandin 15-hydroxydehydrogenase in-vitro and of prostaglandin inactivation in perfused lung by the new azobenzene analogue, Ph CL 28A.

The new azobenzene analogue Ph CL 28A (2-hydroxy-5-(3,5-dimethoxycarbonyl-benzoyl)-benzene acetic acid) potently inhibited prostaglandin 15-hydroxydehydrogenase (PGDH) in the nanomolar range in-vitro and inhibited prostaglandin inactivation in rat perfused lung at similar concentrations, and is the most potent PGDH inhibitor yet available. It was synthesized because electronegative substituents in the B ring of homosalazine enhance PGDH inhibitory potency. Ph CL 28A inhibited human placental PGDH non-competitively with regard both to substrate PGF2 alpha (Ki = 18.7 +/- 0.9 nM) and the NAD+ cofactor (Ki = 57.6 +/- 2.9 nM); inhibition was greatly reduced at pH greater than or equal to 8.0. Ph CL 28A hydrolyses spontaneously in alkali (t1/2 at pH 9.0 = 45 h) to the less active dicarboxylic acid (IC50 human placental PGDH 1.6 microM versus 0.028 microM for Ph CL 28A). The new analogue is 1000 X more active than the parent compound sulphasalazine from which it derives. The IC50 values for five azobenzene analogues in rat perfused lung (Ph CL 28A = 72 nM) correlated strongly with those obtained using purified PGDH (r = 0.99), suggesting that they inhibit pulmonary prostaglandin degradation at the enzyme step rather than at the hypothetical carrier. The new compound will be a useful probe for PGDH structure and function.

Animals↗
PubMed1984

Enzymatic inactivation of 6-keto-prostaglandin E1 in vitro: comparison with prostaglandin E1.

The inactivation of 6-keto PGE1, a biologically active and stable metabolite of prostacyclin, was studied in 100,000 g cytosolic supernatants by bioassay on rat stomach strip (contraction) and human platelets (inhibition of ADP-induced aggregation). PGE1 was used as a reference compound. Both PGs were inactivated in supernatants from colon, kidney and liver of rat, rabbit and guinea-pig. Inactivation was time- and NAD+ -dependent and was generally greater for PGE1 than 6-keto-PGE1. The enzyme responsible for 6-keto-PGE1 inactivation in cytosolic supernatants is distinct from prostaglandin 15-hydroxydehydrogenase and 9-keto reductase, is not inhibitable by sulphasalazine-like drugs and its activity is recoverable after precipitation by ammonium sulphate. We conclude that 6-keto-PGE1 can be inactivated by enzymes with wide tissue distribution, but further studies are needed for identification of these novel enzymes and the products formed as well as to assess their significance in the intact animal.

Alprostadil↗
PubMed1983

Inhibition of prostaglandin 15-hydroxydehydrogenase by sulphasalazine and a novel series of potent analogues.

The ability of sulphasalazine, its colonic metabolites and various analogues to inhibit prostaglandin inactivation by two purified preparations of type INAD+-dependent prostaglandin 15-hydroxydehydrogenase or in various 100,000 g cytosolic supernatants was investigated using PGF2 alpha as substrate and radio-TLC. Bovine lung and human placental PGDH were inhibited in a dose-dependent and apparently non-competitive manner by sulphasalazine and most of the 26 salazine/sulphasalazine analogues tested, but the potencies of the analogues varied considerably. In a survey of structure-activity effects testing 30 drugs at a fixed dose (50 microM) in six test systems, it was established that only two aromatic rings are needed and that optimal PGDH inhibition requires -CH2COOH and -OH at positions 1 and 2 in the salicyl C ring system. Homosalazine was thus established as the type compound of a novel series of powerful PGDH inhibitors. Electronegative substituents meta or para in ring B produce compounds with greater than 150 X inhibitory potency of sulphasalazine, and a significant linear correlation (r = 0.82, P less than 0.002) was found between the inhibitory activity and the Hammett sigma substituent constant in this series of ten homosalazine analogues.

Animals↗
PubMed1983

6-Keto-prostaglandin E1: its formation by platelets from prostacyclin and resistance to pulmonary degradation.

6-Keto-prostaglandin E1 is a novel biologically active product of the metabolism of prostacyclin in liver and platelets. Further evidence for this bioconversion was obtained in stirred suspensions of platelet rich plasma (PRP) and resuspended platelets (RSP) by sampling and simultaneous assay on a superfusion cascade (rabbit coeliac artery, rat stomach fundus strip) and on human platelet aggregation. Incubation of prostacyclin in saline led to rapid loss of bioactivity (t1/2 3.2 min); its stability was prolonged in platelet poor plasma (t1/2 25.1 min). However, in PRP and RSP a more spasmogenic product was generated transiently. 6-Keto-PGE1, was 3.0 and 2.5 times more potent on the two bioassay tissues, respectively, but approximately 3 times less so as inhibitor of platelet aggregation. 6-Keto-PGE1 is not extensively metabolised in the isolated perfused rat lung (20.4 or 4.2%, depending on protocol), compared with PGE1 (84.3 or 78.5%), and is a much poorer substrate for the principal prostaglandin metabolising enzyme, prostaglandin 15-hydroxydehydrogenase. These data show that 6-keto-PGE1 is a biologically active but pulmonary-resistant product of prostacyclin metabolism but does not resolve the claim that it might have physiological relevance.

Alprostadil↗