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Biomedical subjects

E J Corey

Publications and source records attributed to E J Corey.

At least 181 records · Page 10Linked to original sources
PubMed1982

Radioimmunoassay for leukotriene B4.

A rabbit immunized with leukotriene B(4) [LTB(4); (5S,12R)-6, 14-cis-8, 10-trans-icosatetraenoic acid] coupled to bovine serum albumin via the 12-oxy function of the lipid produced antibodies having an average association constant (K(a)) for [14,15-(3)H]LTB(4) of 3.2 x 10(9) M(-1) at 37 degrees C and in a concentration of 0.37 mug/ml of the immune plasma. When 10 mul of anti-LTB(4) and 3.9 nCi of [14,15-(3)H]LTB(4) (28 Ci/mmol; 1 Ci = 3.7 x 10(10) becquerels) were incubated in a volume of 250 mul, 50% inhibition of radioligand binding was achieved with 0.31 ng of LTB(4) and with 1.95 ng of (5S,12S)-6-trans-8-cis-LTB(4). The sulfidopeptide leukotrienes, LTC(4) and LTD(4), displaced the radioligand from this antibody with less than 1/100th the activity of LTB(4), and the diastereoisomers of 6-trans-LTB(4), 5-L-hydroxy-6-trans-8,11,14-cis-icosatetraenoic acid (5-HETE), and three prostaglandins were minimally effective. The specificity of this radioimmunoassay was further shown by assessment of the immunoreactive products generated from calcium ionophore (A23187)-activated rat serosal mast cells and human neutrophils after reversed-phase HPLC. Resolution of the supernatants from each cell type yielded a single immunoreactive peak that coeluted with synthetic LTB(4) and quantitatively correlated with the physical measurement by integrated A(269) in that peak; UV-absorbing peaks eluting at other retention times were not immunoreactive. The immunoreactive LTB(4) generated averaged 4.6 ng per 10(6) rat mast cells and resolution of the supernatants by reversed-phase HPLC without a prior extraction step gave a recovery of 54%, validating the direct applicability of this sensitive and specific assay for LTB(4), a highly potent chemotactic factor, to unfractionated biologic fluids.

Animals↗
PubMed1982

Effects of leukotriene E on pulmonary mechanics in the guinea pig.

The effects of intravenously infused 5(S)hydroxy-6(R)-S-cysteinyl-7,9,-trans,11,14,-cis eicosatetraenoic acid (leukotriene E) (LTE), one of the leukotriene constituents of slow-reacting substance of anaphylaxis (SRS-A), on pulmonary resistance (RL) and dynamic compliance (Cdyn), breathing frequency, and mean systemic arterial pressure were determined in both anesthetized and unanesthetized guinea pigs. The LTE caused a dose-dependent increase of RL and decrease in Cdyn over the range of doses from 100 to 10,000 ng/kg with significance effects at the highest doses. The onset of effect after a significant dose occurred within 30 s and was maximal 1 to 3 min after infusion. The LTE elicits a significantly greater effect on RL for a given change in Cdyn than occurs with LTC or LTD indicating that LTE is a less selective peripheral airway agonist than LTC or LTD. The LTD infusion resembled LTC or LTD in evoking a systemic arterial hypotension that was preceded by a brief initial period of hypertension in unanesthetized animals.

Airway Resistance↗
PubMed1982

Leukotrienes C4, D4 and E4: effects on human and guinea-pig cardiac preparations in vitro.

The effects of leukotrienes C4, D4 and E4 (LT C4, D4 and E4) were studied in isolated preparations of guinea-pig and human myocardium in order to assess their contribution to cardiac dysfunction associated with systemic anaphylaxis. LT C4, D4 and E4 all caused long-lasting and dose-related decreases in the contractile force and coronary flow rate of the isolated guinea-pig heart. The rank order of potency was LT D4 greater than C4 greater than E4. The effects of LT C4 and D4 were antagonized by the anti-slow-reacting-substance compound FPL 55712. The negative inotropic effect of LT is unlikely to be secondary to the concomitant reduction in coronary flow because: 1) the same reduction in coronary flow by angiotensin II resulted in a negligible decrease in contractility and 2) the negative inotropic effect of LT also occurred in the electrically paced, noncoronary perfused left atrium and right ventricular papillary muscle of the guinea pig and in pectinate muscles obtained from surgical specimens of human right atrial appendage. LT D4 potentiated the positive chronotropic effect of histamine, supporting the concept that functional interactions occur between the various mediators of immediate hypersensitivity. The cardiac effects of pure synthetic LT are similar to those previously obtained with crude slow-reacting substance of anaphylaxis indicating that the prolonged contractile failure associated with systemic anaphylaxis largely could be due to the negative inotropic effect of LT. Because LT are released in a variety of immunological and inflammatory reactions, their potent myocardial depressant effects may play a role in cardiac dysfunction associated with these reactions.

Abdomen↗
PubMed1981

Functional characterization of synthetic leukotriene B and its stereochemical isomers.

Leukotriene B (LTB), a potent lipid chemotactic factor for neutrophils, is 5S,12R-dihydroxy-6,14-cis,8,10-trans-eicosatetraenoic acid (Fig 1), based upon direct comparison of natural LTB with synthetic 5S,12R-dihydroxy-6,8,10,14-eicosatetraenoic acid (5,12-di-HETE) stereoisomers in three biological assays. Of the six synthetic stereoisomers evaluated, only the 5S,12R,6,14-cis,8,10-trans compound had chemotactic potency for human neutrophils in vitro that was comparable to that of natural LTB, with a concentration of 3 X 10(9-9) M eliciting a one-half maximum response. In contrast, the racemic mixture of 5R,12R- and 5S,12S-6,10-trans,8,14-cis, the racemic mixture of 5S,12R- and 5R,12S-6,10-trans,8,14-cis, the 5S,12R-6,8-trans,10,14-cis, the 5S,12R-6,8,10-trans,14-cis, and the 5S,12S-6,8,10-trans,14-cis stereoisomers required concentrations of 3 X 10(-7) to 1 X 10(-6) M to elicit comparable responses. Only natural LTB and its synthetic counterpart elicited a local neutrophil infiltration when injected into the skin of the rhesus monkey at 10 ng and 100 ng per site. Natural and synthetic LTB at a concentration of 3 X 10(-8) M each provoked an EC25 contractile response of guinea pig pulmonary parenchymal strips in vitro, whereas the other four tested stereoisomers of 5,12-di-HETE were inactive at this concentration. Structure-function analyses suggest that the neutrophil chemotactic activity depends critically upon the C-1 to C-12 domain, including the stereochemistry of the 6-,8-,and 10-olefinic bonds and the presence of both hydroxyl groups.

Animals↗
PubMed1981

Pharmacological activity of leukotrienes A4, B4, C4 and D4 on selected guinea-pig, rat, rabbit and human smooth muscles.

The myotropic activity of leukotrienes A4, B4, C4, D4 and histamine has been evaluated on selected smooth muscle preparations. LTA4, B4, C4 and D4 were several times more potent than histamine on the guinea-pig lung parenchymal strip, while on the guinea-pig trachea, LTB4 was less active. The guinea-pig ileum either in segments or in strips of longitudinal muscles responses well to LTC4, LTD4 and histamine but not to LTA4 and LTB4. Rat and rabbit lung parenchymal strip showed very little sensitivity for leukotrienes whereas human parenchymal strips and bronchi were nearly as sensitive as the guinea-pig lung.

Animals↗
PubMed1981

Radioimmunoassay of the leukotrienes of slow reacting substance of anaphylaxis.

A rabbit immunized with a conjugate of leukotriene D4 (LTD4) and bovine albumin via the icosanoid carboxyl produced antibodies with comparable affinities for leukotrienes C4, D4, and E4 (LTC4, LTD4, and LTE4) and their 11-trans stereoisomers. The antibodies bound 3H-labeled 11-trans-LTC4 and 11-trans-LTC4 with the same average association constant (Ka) of 2.8 x 10(9) M-1 at 37 degrees C and were present at a concentration of 0.32 microgram/ml of the immune rabbit plasma. When 9.5 microliter of anti-LTD4 and 108 pmol of 11-trans-[3H]LTC4 (40 Ci/mmol) were incubated in a volume of 300 microliter with LTC4, LTD4, LTE4, or their 11-trans stereoisomers, 50% inhibition of 11-trans-[3H]LTC4 binding was achieved at levels varying between 0.3 and 0.7 ng. As assessed with synthetic analogs of the natural leukotrienes, the antibodies recognized neither those changes within the 6-sulfidopeptide unit of LTD4 produced by deamination or modest peptide lengthening nor the specific stereochemistry of the delta 14-cis double bond. However, the antibodies did recognize the triene lipid domain and the position and spatial orientation of the glutathione or cysteinylglycine function. Binding of 11-trans-[3H]LTC4 by anti-LTD4 was not inhibited by glutathione, cystinylbisglycine, arachidonic acid, or 5-hydroxy-6,8,11,14-icosatetraenoic acid, and leukotriene B4 (LTB4) was about 1/1000th as active as LTC4, LTD4, or LTE4. Mouse lymphoma (WEHI-5) and rat basophil leukemia (RBL-1) cells, when stimulated with calcium ionophore A23187, each produced immunoreactive leukotrienes; and LTC4, LTD4, and LTE4 from RBL-1 cells were individually quantitated by radioimmunoassay after resolution by high-performance liquid chromatography.

Animals↗
PubMed1981

Contractile activities of structural analogs of leukotrienes C and D: necessity of a hydrophobic region.

Sixteen structural analogs of leukotrienes C and D were tested for their contractile activities on guinea pig pulmonary parenchymal strip and ileum. The analogs differed from the native structures in the position of either the thioether-linked peptide side chain or the hydroxyl group (or both) or in the number and positions of ethylenic bonds. Analogs in which the thioether-linked peptide chain was attached other than at the C-6 position had substantial reductions in activity on both smooth muscle preparations, whereas analogs in which the various ethylenic bonds were saturated retained substantial contractile activity in both assays. These observations demonstrate that, although a hydrophobic region of the eicosinoid is necessary for contractile activity, the length of this segment is more critical than its precise stereochemistry. Analogs of leukotrienes based on the possibility of parallel biosynthetic routes deriving from 8-, 11-, and 15-hydroperoxyeicosatetraenoic acid as precursors were found to effect a comparatively weak contractile response so that their role as biological agents in this respect seems unlikely.

Animals↗
PubMed1981

Contractile activities of structural analogs of leukotrienes C and D: role of the polar substituents.

Twenty-three structural analogs of the leukotriene components of slow reacting substance of anaphylaxis (SRS-A), in which the polar regions of the leukotriene were systematically modified, were tested for their contractile activities on guinea pig pulmonary parenchymal strips and guinea pig ileum. The structural modifications allowed evaluation of the separate contributions of the four polar units in the C-1 to C-6 region of the SRS-A leukotrienes to smooth muscle spasmogenic activity. The free NH2-terminal amino group of the S-linked peptide was necessary for full activity, and its deletion or substitution reduced activity by more than one but less than two orders of magnitude. A similar level of importance was apparent for the free glycine carboxyl group. In contrast, a free eicosanoid carboxyl at C-1 is not required for full activity on the airway and for substantial activity on the ileum. A role for the C-5 hydroxyl is indicated by the inactivity of the one available 5-desoxy analog. Nucleophilic, divalent sulfur is not critical to leukotriene D (LTD) activity, in that one sulfoxide had substantial function. The conformational relationship between the eicosanoid and peptide moieties of LTD is of considerable importance in that epimers at the C-5 or C-6 position were less active than LTD by more than two orders of magnitude. Several lines of evidence suggest that the relative geometrical arrangement of the C20 chain and the peptide unit is important to activity, consistent with the existence of a true receptor for LTD.

Animals↗
PubMed1980

Leukotriene A. Isolation from human polymorphonuclear leukocytes.

Leukotriene A, an unstable intermediate in the conversion of arachidonic acid to stable leukotrienes, was isolated from human polymorphonuclear leukocytes. The allylic epoxide intermediate is rapidly hydrolyzed under acidic conditions. A method was therefore developed for esterification and extraction of the intermediate as the methyl ester from an alkaline aqueous phase, into an aprotic solvent. This was achieved by addition of methanol and an excess of diazomethane in ether to the incubatio mixture, followed by addition of water, and phase separation. The identity of the isolated compound with the previously synthesized methyl ester of 5 (S)-trans-5,6-oxido-7,9-trans-11,14-cis-eicostatetraenoic acid (leukotriene A), was established by comparing chromatographic and chemical properties of the isolated compound and synthetic leukotriene A.

Arachidonic Acids↗