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Biomedical subjects

R E Duque

Publications and source records attributed to R E Duque.

28 records · Page 2Linked to original sources
PubMed1986

Inhibition of neutrophil activation by p-bromophenacyl bromide and its effects on phospholipase A2.

In an effort to elucidate the nature of the inhibitory effects of p-bromophenacyl bromide (pBPB) on neutrophil stimulation, we have examined its effects on several stages of stimulus-response coupling. Pretreatment of rat neutrophils with pBPB resulted in a dose- and time-dependent irreversible inhibition of both N-formylmethionyl-leucylphenylalanine (fMet-Leu-Phe)-induced lysosomal enzyme release and change in transmembrane potential. Inhibition of the biological responses to the chemotactic peptide fMet-Leu-Phe was not due to receptor inactivation since fMet-Leu-[3H]-Phe binding to the formyl peptide receptor was not significantly altered by pBPB pretreatment. Inhibition by pBPB of phorbol myristate acetate (PMA)-induced changes in transmembrane potential and the generation of superoxide (0-2) was also observed. pBPB treatment appeared to inhibit activation of the NADPH oxidase without a direct effect on the oxidase itself. This inhibitory effect was not accompanied by cell death or decrease in cellular titratable sulphydryl groups (at least at doses less than 20 microM). There was, however, significant inhibition of a membranous fraction of fMet-Leu-Phe-induced phospholipase A2 activity by pretreatment with 10 microM pBPB, although total cellular phospholipase A2 was only minimally (less than 20% inhibition) affected. These data would indicate that pBPB inhibits an early event associated with stimulus-response coupling in rat polymorphonuclear leukocytes (i.e. change in transmembrane potential). The inhibitory effects of pBPB may be secondary to the inhibition of a critical membranous fraction of cell bound phospholipase A2 activity or its activation, necessary for the initiation of cell activation.

Acetophenones↗
PubMed1985

Functional defects in phagocytic cells following thermal injury. Application of flow cytometric analysis.

Defective phagocytic cell function may partially account for the morbidity and mortality associated with thermal injury. In experimental thermal injury in the rat, small circulating blood volumes increase the difficulty in obtaining significant data. Furthermore, purification and or elicitation procedures have the potential for altering the cell surface characteristics and/or the functional response of the cell in question. We have examined the circulating neutrophils and pulmonary alveolar macrophages of anesthetized rats following a 16-20% body surface area scald injury to the shaved back. The circulating neutrophils of thermally injured rats were examined by flow cytometry following stimulation with phorbol myristate acetate (PMA) (100 ng/ml) in terms of the change in fluorescence intensity of the potentiometric cyanine dye, dipentyloxocarboxyanine and the formation of the oxidized product of 2',7'-dichlorofluorescin diacetate-loaded cells. The alveolar macrophages were examined after stimulation with PMA (100 ng/ml) in terms of the change in fluorescence intensity of the potentiometric dye, dipropylthiodicarbocyanine and the generation of superoxide production, as assessed by the superoxide dismutase inhibitable reduction of cytochrome c. Both cells exhibited a profound inhibition of cell function 4 hours after the insult, with partial return toward control values at later time points. Furthermore, the plasma of thermally injured rats, 4 hours after the burn was inhibitory to normal rat neutrophils. Fluorescent compounds suggestive of in vivo lipid peroxidation were maximally detectable at this time point. Further research is needed to establish the role of these products in the induction of phagocytic cell dysfunction.

Animals↗
PubMed1984

Prostaglandin modulation of N-formylmethionylleucylphenylalanine-induced transmembrane potential changes in rat neutrophils.

Prostaglandins of the E-series (PGEs) and PGI2 will inhibit formylmethionylleucylphenylalanine-(f-Met-Leu-Phe) induced lysosomal enzyme release and superoxide-anion (O2-) production by neutrophils. The inhibitory effects of PGEs and PGI2 on neutrophil functional responses have been correlated with their ability to increase intracellular cAMP. In this study we have examined the effects of PGEs and PGI2 on f-Met-Leu-Phe- and phorbol-myristate-acetate-induced rat neutrophil membrane potential changes using an optical probe of membrane potential 3,3-dipropylthiodicarbocyanine iodide. 15-(S)-15-methyl-PGE1 (15-methyl-PGE1), a stable analogue of PGE1 and PGI2 inhibited f-Met-Leu-Phe-induced transmembrane potential changes in a dose-dependent manner. This inhibition was correlated with the ability of these agents to increase intracellular cAMP levels and inhibit O2- production and degranulation. In contrast, 15-methyl-PGE1 and PGI2, did not inhibit phorbol-myristate-acetate-induced transmembrane potential changes and O2- production. These results suggest independent mechanisms of activation of neutrophils by phorbol myristate acetate and f-Met-Leu-Phe, and they also suggest that the inhibitory effects of prostaglandins and cAMP on f-Met-Leu-Phe-stimulated cells is at a step or steps prior to activation of those processes involved in effecting changes in transmembrane potential, which are common to both stimuli.

Alprostadil↗
PubMed1983

Inhibition by tosyl-L-phenylalanyl chloromethyl ketone of membrane potential changes in rat neutrophils. Correlation with the inhibition of biological activity.

A plasma membrane-associated serine esterase (protease) has previously been reported to be required during stimulation of a variety of cell types. In this study we have examined the role of such a protease on membrane potential changes using an optical probe of membrane potential 3,3'-dipropylthiodicarbocyanine iodide. The irreversible chymotrypsin-like protease inhibitor TPCK (tosyl-L-phenylalanyl chloromethyl ketone) inhibited membrane potential changes in rat neutrophils in response to phorbol myristate acetate, N-formylmethionylleucylphenylalanine and the calcium ionophore A23187 in a time- and dose-dependent manner. This inhibition was correlated with the known inhibitory effects on superoxide (O-2) generation and enzyme release (lysozyme and beta-glucuronidase). High external calcium concentrations overcame the inhibitory effects of TPCK on A23187-induced stimulation but had no effect on the inhibition of N-formylmethionylleucylphenylalanine stimulation. These results suggest that a TPCK-inhibitable activity is required for the development of the membrane potential changes that are coupled to subsequent secretory events and precede a calcium requiring activity.

Acetates↗
PubMed1983

The macrophage adherence phenomenon: its relationship to prostaglandin E2 and superoxide anion production and changes in transmembrane potential.

Mononuclear phagocytes are undoubtedly the sine qua non of chronic inflammatory reactions. This is demonstrated by their unique ability to function as phagocytic, secretory, or effector cells during the course of an immune event. Although macrophages can perform a variety of immune tasks, their ability to function appropriately is dependent upon the mode of elicitation, the stimulus under investigation, the source of the macrophages (peritoneal, alveolar, etc.), and whether the macrophages are monolayers or in suspension. We have examined the relationship between adherent and non-adherent elicited peritoneal macrophages in terms of prostaglandin E2 (PGE2) and superoxide anion (O2-) production; in addition, we have studied these elicited macrophages in suspension for their ability to undergo transmembrane potential changes in response to several stimuli. Non-adherent, elicited peritoneal macrophages demonstrated an increase in basal PGE2 production, and were refractory to particulate stimulus. After monolayer formation, basal PGE2 levels dropped and the cells could respond to both soluble and particulate stimuli. Only adherent macrophages could respond to a specific challenge and synthesize O2-. Both O2- production and depolarization of the transmembrane potential were suppressed in cells in suspension. Furthermore, both exogenous PGE2 and supernatant from macrophages in suspension could modulate O2- production by PMA challenged macrophages monolayers. These studies indicate that PGE2 may modulate macrophage function and dictate activity as macrophages go from the non-adherent to adherent state.

Animals↗
PubMed1983

Effect of the beige mutation on bleomycin-induced pulmonary fibrosis in mice.

A single endotracheal administration of bleomycin causes pulmonary fibrosis in several animal species. In view of the functional deficits in neutrophil function as a result of the beige mouse (bg/bg) mutation, its effect on bleomycin-induced pulmonary fibrosis was examined to evaluate the role of the neutrophil in such a response. Neutrophils from beige mice showed a selective defect in the ability to degranulate in response to cytochalasin B and formyl-methionyl-leucyl-phenylalanine, without impairing their ability to produce superoxide anion and H2O2 in response to the same stimuli as well as phorbol myristate acetate. Despite this functional deficit, beige mice responded more intensely to bleomycin than did their heterozygote controls at both 2 wk and 1 month after drug instillation, as assessed by both lung collagen and deposition. This suggests that the inability to mobilize hydrolytic enzymes has no effect on the ability to mount a fibrogenic response, and it would even be detrimental by enhancing such a response caused by decreased connective tissue catabolism as a consequence of the inability to release the granule enzymes to the extracellular space.

Animals↗
PubMed1983

In vitro and in vivo stimulation of rat neutrophils and alveolar macrophages by immune complexes. Production of O-2 and H2O2.

Rat neutrophils and alveolar macrophages were quantitatively studied for production of O-2 and H2O2 after incubation of cells with immune complexes, and the responses were compared with those produced after cell contact with phorbal myristate acetate or zymosan particles. The production of toxic oxygen products is a linear function of cell number, the duration of incubation, and the amount of immune complex employed. In the case of neutrophils, there is a direct relationship between the amounts of immune complex internalized, secretory release of lysosomal enzymes, and production of O-2 and H2O2. With both neutrophils as well as alveolar macrophages, maximal production of O-2 occurs with the largest complexes (formed under conditions of antigen equivalence). When limiting cell concentrations are used, alveolar macrophages produce considerably more oxygen products than an equivalent number of peritoneal neutrophils obtained from the same animals. Thus, alveolar macrophages as well as neutrophils represent important potential sources for the generation of toxic oxygen products in lung inflammatory reactions. Experiments have also been designed to estimate the relative contributions of neutrophils and alveolar macrophages in vivo during acute immune complex deposition in lung. The data indicate that both neutrophils and alveolar macrophages are activated by in vivo exposure to immune complexes, each cell type producing a 2-4-fold increase (over baseline levels) in the amounts of O-2. Thus, alveolar macrophages as well as neutrophils may play an important role in the generation of toxic oxygen products that have been incriminated in the pathogenesis of acute lung injury following deposition of immune complexes.

Acetylglucosaminidase↗
PubMedDate not supplied

Oxidative product formation in irradiated neutrophils. A flow cytometric analysis.

The effect of irradiation on neutrophil oxidative function was evaluated using a flow cytometric assay of intracellular hydrogen peroxide (H2O2) production. This assay quantitates the H2O2-dependent conversion of the nonfluorescent compound, 2'-7'-dichlorofluorescein (DCFH), into fluorescent 2'-7'-dichlorofluorescein (DCF) on a single-cell basis. Intracellular H2O2 production in response to stimulation with phorbol myristate acetate was not affected by neutrophil irradiation at doses up to 2500 rad. In addition, irradiation of intracellular DCFH and aqueous 2'-7'-dichlorofluorescein diacetate (DCFH-DA) resulted in DCF production, which suggested that oxidative molecules produced by aqueous radiolysis were detected by this assay. This study indicates that radiation doses of 1500 to 2500 rad, which are sufficient to prevent induction of graft-versus-host disease by transfused blood components, are not deleterious to neutrophil oxidative metabolism.

Flow Cytometry↗
PubMedDate not supplied

[1st Latin American consensus conference on immunologic typing of leukemias].

On October 16, 1996, the first Latinamerican Consensus Conference for the Immunophenotyping of Leukemia took place in the City of Puebla, Mexico, with representatives from ten countries of the region, and two external consultants. This document summarizes the major conclusions where scientific consensus was achieved.

Antigens, CD↗