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Biomedical subjects

E L Becker

Publications and source records attributed to E L Becker.

At least 163 records · Page 9Linked to original sources
PubMed1975

Lysosomal enzyme secretion and volume contraction induced in neutrophils by cytochalasin B, chemotactic factor and A23187.

The secretion of lysosomal enzymes from rabbit peritoneal polymorphonuclear leukocytes caused by either cytochalasin B, or cytochalasin B plus chemotactic factors, or by the divalent ionophore, A23187, is associated with a decrease in the volume of these same cells. No quantitative correlation could be found between the extent of lysosomal enzyme secretion and volume decrease for any of the three stimuli. This suggests that the volume decrease is neither the direct cause nor the result of the secretion.

Animals↗
PubMed1975

Volume changes induced in rabbit polymorphonuclear leukocytes by chemotactic factor and cytochalasin B.

Incubation of rabbit neutrophils with various chemotactic factors causes an expansion of their volume. The expansion shows a high correlation with the chemotactic responsiveness of these cells, requires metabolic energy, and is independent of the presence of divalent cations. Cytochalasin B causes a decrease in the volume of the neutrophil. This decrease also requires metabolic energy and is independent of divalent cations. In the presence of cytochalasin B, the chemotactic factor, instead of acting to expand cell volume, induces a further contraction of the cell; this decrease requires Ca2+ in the external medium.

Animals↗
PubMed1975

The isolation and partial characterization of neutrophil chemotactic factors from Escherichia coli.

Heat-stable, chemotactically active peptides have been obtained from Escherichia coli culture filtrates. They range in size between 150 and 1500 daltons and are anionic at neutral pH. Free carboxyl groups but not free amino groups appear to be required for activity. The N-terminal group may be blocked. There do not appear to be internal aromatic or basic residues in the chemotactically active fractions. A highly purified, not completely characterized, fraction was found to contain aspartic acid, serine, glutamic acid, alanine, and glycine.

Acetylation↗
PubMed1975

The role of cyclic AMP in the chemotactic responsiveness and spontaneous motility of rabbit peritoneal neutrophils. The inhibition of neutrophil movement and the elevation of cyclic AMP levels by catecholamines, prostaglandins, theophylline and cholera toxin.

Agents known to affect intracellular levels of cyclic AMP in many diverse systems have been tested for their effect on the chemotaxis induced by Escherichia coli culture filtrates, spontaneous motility and cyclic AMP levels of rabbit peritoneal neutrophils. Prostaglandin E1 and A1 but not prostaglandin F2alpha increased neutrophil cyclic AMP levels and, correspondingly, only the former two prostaglandins inhibited chemotaxis. Nevertheless, a quantitative relationship between prostaglandin stimulation of cyclic AMP and inhibition of chemotaxis could not be found. Epinephrine, isoproterenol, and, to a much lesser extent, norepinephrine increased neutrophil cyclic AMP through beta adrenergic stimulation. Only epinephrine and isoproterenol inhibited chemotaxis, but the inhibition was variable and not related to the ability of these catecholamines to increase intracellular cyclic AMP. Cholera toxin increased neutrophil cyclic AMP after a 30-min lag period which paralled its inhibitory effect on chemotaxis and spontaneous motility. However, the effect on chemotaxis require 50 ng/ml of toxin whereas the effect on cyclic AMP was manifested at 2 ng/ml of toxin. Prior to 30-min preincubation there was no effect of even 1250 ng/ml of toxin on either cyclic AMP or chemotaxis. Choleragenoid prevented the effects of toxin on both cyclic AMP and chemotaxis. The bacterial chemotactic factor obtained from E. coli culture filtrates did not effect a measurable change in levels of neutrophil cyclic AMP. The data indicate that even though cyclic AMP is not, in the main sequence of events, triggering the chemotactic response, increases in neutrophil cyclic AMP may modulate the movement and thus the chemotactic responsiveness of the neutrophil.

Animals↗
PubMed1972

The relationship of the chemotactic behavior of the complement-derived factors, C3a, C5a, and C567, and a bacterial chemotactic factor to their ability to activate the proesterase 1 of rabbit polymorphonuclear leukocytes.

The inhibition profiles obtained when a series of p-nitrophenyl ethyl alkylphosphonates and of p-nitrophenyl ethyl chloroalkylphosphonates were used to interfere with the chemotactic activity of polymorphonuclear leukocytes stimulated by C3a, C5a, and bacterial factor were the same as found previously when C567 was the chemotactic agent. This indicates that as in the chemotactic activity induced by C567, an obligatory step in the chemotaxis caused by C3a, C5a, and bacterial factor is the activation of proesterase 1 of the rabbit polymorphonuclear leukocyte. C5a and C3a activate proesterase 1 of peripheral blood polymophonuclear leukocytes as measured by the increase of acetyl DL-phenylalanine beta-naphthyl esterase activity. Attempts to detect in a like manner the proesterase 1 of the same leukocytes using bacterial factor under varying circumstances have consistently failed. It is concluded that bacterial factor, for unknown reasons, is unable to activate proesterase 1 to the same extent as the complement-derived chemotactic factors. The hypothesis of there being a quantitative difference in the ability of bacterial factor to activate proesterase 1 compared with the complement-derived factors explains the previous observations that bacterial factor can not deactivate to itself or to the complement-derived factors, although these latter factors can deactivate to themselves, to each other, and to the bacterial factor. The quantitative difference in the ability of bacterial factor to activate proesterase 1 compared to the complement-derived factors is also associated with and explains the finding that the maximal chemotactic activity attainable when bacterial factor is the chemotactic agent is distinctly less than that obtained using either C3a, C5a, or C567. These results indicate that the activation of proesterase 1 is a general requirement for the chemotactic activity of rabbit polymorphonuclear leukocytes with known macromolecular chemotactic agents and suggest that under several different circumstances the level of chemotactic activity attained is related to the degree of such activation.

Animals↗