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Biomedical subjects

E L Becker

Publications and source records attributed to E L Becker.

At least 199 records · Page 11Linked to original sources
PubMed1967

Mechanisms of the inhibition of chemotaxis by phosphonate esters.

Studies in the time course of the response of rabbit polymorphonuclear leukocytes (PMN's) to the complement-associated chemotactic factor have revealed that the response is virtually complete by 60 min with less than 15% additionally responding cells thereafter. Phosphonate esters with a well defined capacity to inhibit serine esterases have been used to study the cell-associated enzymes of the rabbit PMN required for the chemotactic response. Two types of inhibition of the cell response to the chemotactic factor have been found: (a) cell-dependent inhibition occurring as a result of pretreatment of PMN's with phosphonate esters; and (b) chemotactic factor-dependent inhibition demonstrated only when the phosphonate ester is present during the chemotactic response. Differences were found in these two modes of inhibition caused by various phosphonates, in terms of their time course of inhibition, in the dose response curves, and in the structure-activity relationships. It has been conclusively demonstrated that the phosphonate esters have no direct inhibitory effect on the chemotactic factor. This has been shown by retention of activity of the chemotactic factor following incubation with phosphonate esters and subsequent removal by dialysis. In addition, the activity of the chemotactic factor and its physical-chemical characteristics in density gradient ultracentrifugation were unaltered in the continued presence of a potent phosphonate inhibitor of chemotaxis. The uptake of the dye trypan blue was studied in cells treated with phosphonate in such a manner to induce cell-dependent inhibition of chemotaxis. Even when 84% cell-dependent inhibition of chemotaxis occurred, no uptake of the dye by leukocytes was found. Thus, phosphonate-induced inhibition of cell responsiveness in chemotaxis was not associated with generalized cell damage as defined by exclusion of the dye. It is concluded that cell-dependent inhibition is due to the presence of a cell-bound esterase which is already activated and thus susceptible to inhibition by phosphonate esters before contact of the cell with the chemotactic factor. The second type of inhibition, chemotactic factor-dependent inhibition, is considered due to a cell-bound esterase which becomes susceptible to inhibition by phosphonate esters only after contact of the PMN with the chemotactic factor. It is postulated that the chemotactic factor activates this phosphonate-resistant precursor making it susceptible to the inhibitory action of the phosphonate ester.

Alcohols↗
PubMed1967

Partial biochemical characterization of the activated esterase required in the complement-dependent chemotaxis of rabbit polymorphonuclear leukocytes.

It was shown in the preceding paper that incubation of the rabbit polymorphonuclearleukocyteswith phosphonate esters leads to an irreversible inhibition of the ability of the leukocyte to respond to the chemotactic factor. This "cell-dependent inhibition" was attributed to the inactivation by the phosphonates of an esterase existing in or on the leukocyte in an already activated state. As shown in this paper, incubating the leukocyte with phosphonate in the presence of certain esters prevents this cell-dependent inhibition. The protection is specific; the ester must be an acetate. Ethyl formate, ethyl propionate, ethyl butyrate, glucose 6-phosphate, fructose 1,6-diphosphate, ATP, tosyl arginine methyl ester, or acetyl tyrosine ethyl ester do not protect. The protection is independent of the phosphonate used to inhibit, and the degree of protection depends on the relative concentrations of acetate and phosphonate. Those acetates which protect are also the esters which inhibit chemotaxis when added to the leukocyte in the upper part of the chemotaxis chamber. It is concluded that the activated esterase is an enzyme capable of specifically splitting, or binding acetates, or doing both. Presumably the esterase is some type of acetylesterase or acetylase. The known aliesterase present in the leukocyte is not the activated esterase. Inhibition of the activated esterase by phosphonates has no effect on endogenous or exogenous glycolysis.

Acetates↗
PubMed1966

Mechanisms of immunologic injury of rat peritoneal mast cells. I. The effect of phosphonate inhibitors on the homocytotropic antibody-mediated histamine release and the first component of rat complement.

The ability of a number of p-nitrophenylethyl, alkyl phenylalkyl, chloroalkyl, and aminoalkyl phosphonates to inhibit the homocytotropic antibody-mediated release of histamine from rat peritoneal mast cells has been tested. The effectiveness of these same phosphonates against the activated first component of rat complement (C'1a) has also been investigated. The rat mast cell esterase activated by the reaction of antigen and homocytotropic antibody resembles chymotrypsin in its reactivity with the phenylalkyl and chloroalkyl phosphonate, but is unlike this protease in its greater responsiveness to the 5-aminopentyl phosphonate relative to the pentyl phosphonate. The antigen-homocytotropic antibody-activated mast cell esterase and chymotrypsin, thus, appear to be similar, but different enzymes; i.e., they are parazymes (see reference 4, p. 501). There are distinct differences in the pattern of inhibition given by the phenylalkyl and aminoalkyl and alkyl phosphonates of the homocytotropic antibody-mediated histamine release from rat peritoneal mast cells and from guinea pig lung slices. On the basis of these differences it is concluded that the esterases activated by the combination of antigen and homocytotropic antibody on the mast cells of the two species are not the same. The arithmetic dose response curve found for the action of the phosphonates on the antigen-induced histamine release from rat peritoneal mast cells contrasted sharply with the logarithmic relationship found when these same inhibitors acted on the guinea pig lung system. This suggests that in addition to the antigen-antibody-activated esterases being unlike, the detailed mode of histamine release from the mast cells of the guinea pig lung differs from that of the mast cells of the rat peritoneum. Distinct and large differences were found in the pattern of inhibition of histamine release from rat peritoneal mast cells and of rat C'1a given by the phenylalkyl, and chloroalkyl and alkyl phosphonates implying that esterase activated by the combination of antigen with the sensitized rat peritoneal mast cells is not C'1a. Thus, the results with the peritoneal mast cells lead to the same conclusion as the previous work with guinea pig lung slices; i.e., the antigen-antibody-activated esterase involved in the homocytotropic antibody-mediated release of histamine is not part of the complement system.

Ancylostomatoidea↗
PubMed1966

Mechanisms of immunologic injury of rat peritoneal mast cells. II. Complement requirement and phosphonate ester inhibition of release of histamine by rabbit anti-rat gamma globulin.

There is an absolute requirement for C'1, C'2, C'4, C'3, and C'5 in releasing histamine from rat peritoneal mast cells sensitized with rabbit anti-rat gamma globulin. This conclusion is based upon the restoration of histamine-releasing capacity by adding highly purified complement components to sera deficient in one or more of these components. Of special advantage was the availability of sera from humans with inborn or acquired deficiencies in a single component. The p-nitrophenyl ethyl phosphonates block this reaction by inhibiting an antigen-antibody-activated esterase which exists in a phosphonate resistant precursor state until activated by the interaction of the sensitized mast cell and serum complement. There is almost complete disparity between the ability of the phosphonates to inhibit complement-dependent histamine release by rabbit anti-RGG and to inactivate C'1a. Even though C'1a is required for complement-dependent histamine release by rabbit anti-RGG, this is not the esterase being blocked by the phosphonates under the experimental conditions used. The pattern of inhibition by the phosphonates of the antigen-antibody-activated esterase required for complement-dependent, noncytotoxic histamine release is remarkably similar to that of the esterase required for homocytotropic antibody-mediated histamine release. One possible implication is that these two quite different modes of carrying out antigen-antibody-induced histamine release from rat peritoneal mast cells lead to activation of the same esterase and share a common pathway.

Animals↗
PubMed1966

Rabbit anaphylactic antibody.

Antibody capable of sensitizing rabbit skin for passive cutaneous anaphylaxis is produced in the rabbit as early as 6 to 7 days following antigenic stimulation. It reaches peak activity around the 9th day and is gone by the 3rd wk. The antibody is heat labile, sensitive to treatment with mercaptoethanol, non-precipitating and does not fix complement. In order to demonstrate PCA activity a latent period is required of from 48 to 72 hr after introduction of the antibody into the rabbit's skin; the activity can persist for at least 17 days. It has a faster electrophoretic mobility than rabbit gammaG-globulin, and is eluted somewhat earlier than gammaG-globulin from Sephadex G-200, although distinctly after gammaM-globulin. No relationship was demonstrated between the rabbit PCA activity and the hemagglutinating activity found in the same sera. The rabbit anaphylactic antibody differs in almost all properties studies from the rabbit 7S antibody capable of sensitizing guinea pigs for PCA which arises at the same time. This latter antibody found early in immunization had properties which were indistinguishable from those described for the rabbit 7S antibody giving PCA in the guinea pig found in late hyperimmune sera.

Anaphylaxis↗
PubMed1966

Release of kallikrein from guinea pig lung during anaphylaxis.

An antigen-antibody reaction occurring in the perfused sensitized guinea pig lung, has been demonstrated to release kallikrein, a proteolytic enzyme related to the formation of kinins. This lung kallikrein is similar to plasma kallikrein in all properties studied, including susceptibility to the same inhibitors, electrophoretic mobility, and heterogeneity in molecular size. The release of kallikrein during anaphylaxis in the guinea pig lung occurs in the presence of ethylenediaminetetraacetate. Perfusion of ellagic acid into nonsensitized lungs will also release kallikrein, presumably through activation of Hageman factor. On the basis of these findings the hypothesis is suggested that the kallikrein in perfused lung activated by the antigen-antibody reaction is, in fact, plasma kallikrein. It is further suggested that activation of such kallikrein by the antigen-antibody reaction proceeds through Hageman factor.

Anaphylaxis↗