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Biomedical subjects

E L Becker

Publications and source records attributed to E L Becker.

At least 145 records · Page 8Linked to original sources
PubMed1977

Stimulated neutrophil locomotion: chemokinesis and chemotaxis.

All leukocytes are capable of responding chemotactically (oriented locomotion) and chemokinetically (stimulated nondirected or random locomotion) to a variety of chemical agents. A brief review of the in vitro and in vivo methods of studying neutrophil movement and our present knowledge of chemotactic factors is presented as well as a discussion on the mechanisms of stimulated movement. Two clinically important instances of defects in neutrophil movement, ie, the Chédiak-Higashi syndrome and a case of actin dysfunction, are herein described.

Ascorbic Acid↗
PubMed1977

The role of an activatable esterase in immune-dependent phagocytosis by human neutrophils.

Diisopropylphosphofluridate, cyclohexyl alkylphosphonofluoridates, and cyclohexyl phenylalkylphosphonofluoridates, which are potent, irreversible inactivators of serine esterases, inhibit the phagocytosis of opsonized sheep erythrocytes by human neutrophils. Two types of inhibition were observed: a) 'cell-dependent' inhibition, which is determined by measuring the ingestion of neutrophils pre treated with the esterase inhibitors and washed; and b) 'phagocytosis-dependent' inhibition, which is due to the presence of the inhibitors during phagocytosis. With the cyclohexyl alkylphosphonofluoridates, phagocytosis-dependent inhibition was always greater than cell-dependent inhibition. Cell-dependent inhibition was irreversible and dependent on the duration of the incubation of neutrophils with inhibitor. Both types of inhibition were dependent on the concentration of the inhibitor. Poorly or non-phosphorylating analogues of the cyclohexyl alkylphosphonofluoridates of DFP were not inhibitory; nor did fluoride, the hydrolysis product of these inhibitors, inhibit ingestion under either condition. In addition, neither method of treating the neutrophils resulted in a decrease in neutrophil viability. Furthermore, pretreating the EAC1423 with the inhibitors did not decrease ingestion. We conclude that cell-dependent inhibition is due to the inactivation of an esterase required for phagocytosis which is in or on the neutrophil in an active form, and thus is susceptible to inhibition by the esterase inactivators before contact of the neutrophil with the phagocytic stimulus. Phagocytosis-dependent inhibition is interpreted as being due to inactivation of an esterase required for phagocytosis which is normally in an inactive precursor proesterase form that is activated by the interaction of the neutrophil with the phagocytic stimulus. The distinctly different inhibition profiles of the active and activatable esterases indicate that they are two different activities.

Cell Adhesion↗
PubMed1976

Activation of stimulus-specific serine esterases (proteases) in the initiation of platelet secretion. I. Demonstration with organophosphorus inhibitors.

The effect of organophosphorus inhibitors of serine esterases (proteases) on secretion from washed rabbit platelets was examined. Five noncytotoxic stimuli were employed: collagen, thrombin, heterologous anti-platelet antibody (in the absence of complement), rabbit C3 bound to zymosan, and platelet activating factor derived from antigen-stimulated, IgE-sensitized rabbit basophils. Diisoprophyl phosphofluoridate, three series of p-nitrophenyl ethyl phosphonates, and a series of cyclohexyl phenylalkylphosphonofluridates were all found to be inhibitory to the platelet secretion. These are irreversible inhibitors of serine proteases but in this system were only inhibitory if added to the platelets concurrently with the stimuli. Pretreatment of either the platelets or the stimuli with the inhibitors followed by washing, was without effect on the subsequent reaction. This suggested the involvement of stimulus-activatable serine proteases in the secretory process. The concept was supported by finding that nonphosphorylating phosphonates or hydrolyzed phosphonates or phosphonofluoridates were without inhibitory action. The effect of a series of phosphonates or phosphonoflouridates in inhibiting each stimulus exhibited a unique activity-structure profile. The demonstration of such unique profiles with four series of inhibitors for each of the five stimuli was interpreted as demonstrating that a specific activatable serine protease was involved in the platelet secretory response to each stimulus.

Animals↗
PubMed1976

Chemotactic activity from rabbit peritoneal neutrophils. Lack of identity with N-acetyl-DL-phenylalanine beta-napthyl esterase.

The chemotactic and N-acetyl-DL-phenylalanine beta-naphthyl esterase activities of rabbit peritoneal neutrophils are separable from each other by both DEAE cellulose and Sephadex G-100 column chromatography. Partially purified esterase obtained from DEAE-cellulose chromatography had molecular weight of 70 000. However, the partially purified fraction contained chemotactic activities with major activity in molecular weight of 28000 and minor activities in the molecular weights of 45000, 21900, 14500 and 10500. Esterase activity is inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate but chemotactic activity is not.

Aminopeptidases↗
PubMed1976

The structure-activity relations of synthetic peptides as chemotactic factors and inducers of lysosomal secretion for neutrophils.

24 di-, tri-, and tetrapeptides have been synthesized as a start of a systematic study of the structural requirements for chemotactic activity and lysosomal enzyme-releasing ability in rabbit neutrophils. All but two of them are N-formyl methionyl peptides. Using the method of Zigmond and Hirsch (10), two representative peptides, F-Met-Leu-Phe and F-Met-Met-Met, were shown to stimulate directed, as well as, random locomotion; thus, they were truly chemotactic. The various peptides showed a wide spread in activity. F-Met-Leu-Phe, the most active peptide studied, had an ED50 for induced migration of 7 X 10(-11) M and for lysozyme and beta-glucuronidase release of 2.4 X 10(-10) M and 2.6 X 10(-10) M, respectively; the least active, Met-Leu-Glu was 26 million times less active in these respects. The relation of activity to structure is exceedingly specific, very small changes in structure making large changes in activity. Moreover, this specificity exhibits a definite regularity and pattern; the activity of a given peptide depends not only on its constituent amino acids but on the position of the amino acid in the peptide chain. Most striking in this last regards is the high activity conferred by phenylalanine when it is in the carboxyl terminal position of a tripeptide, whereas, as the second amino acid from the NH2 terminal end whether in a tripeptide or a dipeptide, it contributes no more to the activity than other amino acids with hydrophobic side chains such as leucine or methionine. The high activity and the specificity and nature of the structural requirements strongly suggest that the primary interaction of peptide and neutrophil leading to either chemotaxis or lysosomal enzyme release is a binding of the peptide with a stereospecific receptor on the neutrophil surface. Whether all chemotactic factors act through the same receptor is not known. An essentially exact correlation exists between the concentrations of the various synthetic peptides required to induce migration and their ability to induce release of lysozyme or beta-glucuronidase. This implies that these two neutrophil functions are triggered by teh same primary interaction; possibly, the binding of the peptides to the same putative receptor. A higher concentration of a given peptide is required to stimulate lysosomal enzyme release than a corresponding migratory response. A slightly but significantly higher concentration of peptide is required to induce beta-glucuronidase secretion than lysozyme release.

Animals↗
PubMed1976

Measurement of chemotaxis of human polymorphonuclear leukocytes in filters by counting the number of cells in a single plane and comparison with leading front method.

A method is described for measuring the chemotactic response in filters of human neutrophils by counting the number of cells in a single plane at a constant distance below the top of the filters. This method gives results that are similar to those obtained by counting the total number of cells that have migrated into the filters. The results obtained by this method are compared with the leading front method. Under most conditions the results are similar whether obtained by the leading front or cell number methods except that counting the number of cells is often more sensitive. In the presence of p-nitrophenyl 4-chlorobutylphosphonate, however, the chemotactic response appeared to be inhibited as determined by counting the number of cells stimulated to migrate but enhanced as measured by the leading front method.

Blood Cell Count↗
PubMed1976

Effect of exogenous cyclic AMP and other adenine nucleotides on neutrophil chemotaxis and motility.

Cyclic AMP placed in the bottom of the modified Boyden chemotaxis chamber is weakly chemotactic for rabbit peritoneal neutrophils. Dibutyryl-cyclic AMP under similar conditions gives a biphasic response, being weakly chemotactic at low concentrations and inhibiting cell movement at higher concentrations. When mixed with the cells in the upper compartment of the chemotaxis chamber, cyclic AMP and dibutyryl-cyclic AMP enhance neutrophil spontaneous motility; on the other hand, dibutyryl-cyclic AMP mixed with the cells in the upper compartment consistently inhibits neutrophil chemotactic responsiveness, while cyclic AMP has a variable effect on chemotaxis. The effect of ADP and ATP was to inhibit chemotaxis and spontaneous motility. AMP is totally without effect.

Adenine Nucleotides↗
PubMed1976

The requirement for esterase activation in the anti-immunoglobulin-triggered movement of B lymphocytes.

In this paper we bring evidence suggesting that there is activation of an esterase upon reaction of anti-immunoglobulin antibodies (anti-Ig) with murine B lymphocytes. B lymphocytes upon exposure to anti-Ig cap the ligand-receptor complexes and immediately afterward become briefly motile. It is this latter step which is inhibitable by exposure to di-isopropyl phosphofluoridate (DFP). Various experimental manipulations indicated that treatment with anti-Ig activates the cell for motility which, however, is not manifested until the temperature is raised to 37 degrees C. The cell incubated with anti-Ig at cold temperatures becomes susceptible to the effect of DFP, suggesting that the antibody-treated cells are activated up to but not beyond the DFP inhibitable step. Exposure of cells to DFP and removal of it before their treatment with anti-Ig does not affect the anti-Ig-induced response. Four lines of evidence indicate that the reduction of lymphocyte movement of DFP is due to the inhibition of an esterase activated by the combination of antibody and cell: 1) The inhibition by DFP is irreversible; once DFP has reacted it can be washed away and the antibody-treated cell is still inhibited. 2) The inhibition increases with time of contact of lymphocytes and DFP and with the concentration of DFP. 3) A very poorly phosphorylating phosphonate, phenyl ethyl pentylphosphonate is completely inactive under conditions where an excellent phosphorylating phosphonate, p nitrophenyl ethyl pentylphosphonate maximally inactivated the cells' movement. 4) The amino acid esters, tosyl L arginine methyl ester and benzoyl arginine methyl ester specifically prevent the inactivation by DFP. The last finding suggests that tosyl L arginine methyl ester and benzoyl L arginine methyl ester might be substrates for the putative antibody-induced lymphocyte esterase. Lymphocytes incubated with antibody in the cold for more than 30 min lose their ability to move when the temperature is raised, suggesting that there is a time-dependent deactivation of the cell.

Amino Acids↗
PubMed1976

The effects of external K+ and Na+ on the chemotaxis of rabbit peritoneal neutrophils.

Extracellular K+ enhances the chemotactic responsiveness and spontaneous movememt of rabbit peritoneal neutrophils but is not required for these functions. Other monovalent cations act the same; the rank order of their effectiveness is K+ = NH4 greater than Rb+ Cs+ greater than Li = Na. The K+ specific ionophore, valinomycin (10-7 M) inhances chemotaxis in the presence of K+ but not in its absence; another K+ specific ionophore, nigericin (10-7 M) inhibits chemotaxis in the absence of K+ but not in its presence. Ouabain (5 x 10-6 M) prevents the enhancing effects of K+ on chemotaxis. Removing the Na+ of the buffer and substituting it with K+, choline or glucose greatly enhances spontaneous motility but depresses chemotactic activity. One hypothesis suggested by the above results is that as a part of their action, chemotactic factors stimulate a net influx of K+ into the neutrophil; an alternative or additional hypothesis is that chemotactic factors stimulate a net efflux of Na+ from the neutrophil.

Animals↗
PubMed1976

The inhibitory effect of chemotactic factors on erythrophagocytosis by human neutrophils.

The effect of various chemotactic factors on phagocytosis of sheep erythrocytes sensitized with IgG and complement (EAC1423) by human neutrophils (PMN) was studied. The bacterial chemotactic factor, a butanol extract of an Escherichia coli culture filtrate, the pronase sensitive and insensitive chemotactic substances isolated from this extract, C5a, a chemotactic fragment of the fifth component of complement, and a chemotactic synthetic peptide, formlymethionyl-leucine all significantly reduced the initial rate of ingestion at concentrations that are chemotactic for PMN. The bacterial chemotactic factor produced a 45 to 75% decrease in the initial rate of ingestion, but did not affect adherence of the EAC1423 and PMN. This same substance had no consistent effect on the total number of EAC1423 ingested at 90 min or longer or on the time interval from the addition of the EAC1423 to the start of ingestion. The inhibitory effect of the bacterial factor increased as the amount of bacterial factor was increased and the inhibitory effect was reversible. Inhibition by bacterial factor could be decreased by increasing the concentration of EAC1423; and if the concentration was increased 3-fold, the inhibition was abolished. These results suggest that inhibition by bacterial factor is competitive in nature.

Cell Adhesion↗
PubMed1976

Some interrelations of neutrophil chemotaxis, lysosomal enzyme secretion, and phagocytosis as revealed by synthetic peptides.

Synthetic oligopeptides of appropriate structure stimulate neutrophil random locomotion, chemotaxis, lysosomal enzyme secretion, and phagocytosis. The structure-activity relationships found for enhanced migration and lysosomal enzyme secretion strongly suggest that the peptides bind to a structurally specific receptor on the neutrophil surface. It is further suggested that the binding of a peptide to the same receptor initiates all of these neutrophil functions. It is postulated that this is accomplished by the receptor-peptide combination initiating a series of parallel but coordinated and interdependent biochemical sequences leading to either microfilament or microtubule activation in addition to other processes. The various functions of the neutrophil differentially utilize the microfilament and microtubule systems.

Animals↗
PubMed1975

Isolation of an N-acetyl-DL-phenylalanine beta-naphthyl esterase from rabbit peritoneal polymorphonuclear leukocytes.

An N-acetyl-DL-phenylalanine beta-naphthyl esterase has been purified 26-fold from rabbit peritoneal polymorphonuclear leukocytes. The purified enzyme was inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate. The apparent Km for hydrolysis of N-acetyl-DL-phenylalanine beta-naphthyl ester is 71 muM. Optimal reaction rates were observed at pH 6-8. No divalent cation requirement for the activation of the enzyme activity was observed. The esterase activity was neither inhibited nor stimulated by bacterial factor, complement component C5a, guanosine 3',5'-monophosphate (cyclic GMP) and adenosine 3',5'-monophosphate (cyclic AMP) which are attractants or repellents for polymorphonuclear leukocytes. High chemotactic activity was observed in the partially purified fraction of the enzyme. The chemotactic activity, like the enzyme activity, was completely inhibited by 10(-7) M phosphonate.

Aminopeptidases↗