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Biomedical subjects

C E McCall

Publications and source records attributed to C E McCall.

At least 73 records · Page 4Linked to original sources
PubMed1981

Role of Ca2+ and Mg2+ in neutrophil hexose transport.

The influence of extracellular Ca2+ and Mg2+ on the transport of 2-deoxy-[3H]glucose into human polymorphonuclear neutrophils was studied. Omission of these cations from the cell suspensions had little effect on resting hexose uptake. Furthermore, the addition of the bivalent cation chelator, EDTA, depressed uptake only slightly. Similarly, neither cation was essential for the enhanced 2-deoxy-D-[3H]glucose uptake stimulated by two chemotactic factors (C5a and N-formylmethionylleucylphenylalanine) and arachidonic acid: enhanced uptake was only partially depressed by the omission of Ca2+ and Mg2+ from the suspensions and was still prominent in the presence of EDTA. Two other neutrophil stimulants, the ionophores, A23187 and ionomycin, also enhanced hexose uptake but their actions were heavily dependent upon extracellular bivalent cations and were totally abrogated by EDTA. In all instances, extracellular Ca2+, but not Mg2+, supported optimal enhanced hexose transport induced by stimuli. Activation of 2-deoxy-D-[3H]glucose uptake by each of the five stimuli was totally blocked by cytochalasin B (a blocker of carrier-mediated hexose transport) and D-glucose but not by L-glucose. The data indicate, therefore, that a variety of neutrophil stimulants activate carrier-mediated hexose transport. Although this transport can be triggered by the movement of extracellular Ca2+ into the cell (as exemplified by the action of the two ionophores), such Ca2+ movement is not required for the actions of chemotactic factors or arachidonic acid. Other mechanisms, such as a rearrangement of intracellular Ca2+, may be involved in mediating the activation of hexose transport induced by the latter stimuli.

Biological Transport, Active↗
PubMed1981

Neutrophil responses to platelet-activating factor.

1-O-Alkyl-2-O-acetyl-sn-glycerol-3-phosphorylcholine (i.e., platelet-activating factor) was prepared and confirmed to possess potent platelet aggregating activity. It was also potent in aggregating and degranulating rabbit and human neutrophils. When injected into rabbits, the lipid induced profound neutropenia, thrombocytopenia, and anaphylactic symptoms. The lyso derivative of this lipid, 1-O-alkyl-sn-glycerol-3-phosphorylcholine, was inactive or several orders of magnitude weaker in inducing these responses. The acetylated lipid appears to be a potent stimulator of both platelets and neutrophils. Its anaphylactic-like toxicity may be related, at least in part, to its ability to aggregate or otherwise stimulate these cells.

Animals↗
PubMed1981

Stimulation of hexose uptake by human eosinophils with chemotactic factors.

The ability of several stimuli, all of which have been reported to stimulate eosinophil motility, to augment uptake or extracellular deoxyglucose (DOG), a glucose analogue, was studied. DOG uptake was stimulated in a concentration-dependent manner by the more potent chemotaxins--zymosan-activated serum, partially purified C5a. N-formyl-methionyl-leucyl-phenylalanine, and 5- and 11-hydroxyeicosatetraenoic acids. Less potent stimuli--the eosinophil chemotactic factor of anaphylaxis, histamine, and prostaglandin E2--did not stimulate DOG uptake. However, the correlation between the abilities of the agents to stimulate motility and DOG uptake was not completely uniform. Prostaglandin F2 alpha was a potent stimulant of DOG uptake yet is known to enhance only weakly chemokinesis and to be not chemotactic for eosinophils. The combined data from this and other studies indicate that these stimuli elicit specific and different sets of functional responses from eosinophils.

Arachidonic Acids↗
PubMed1981

Activation of lysosomal acid phosphatase of eosinophil leukocytes.

Acid phosphatase (AP) within the specific granules of eosinophils is held in a latent, inactive form prior to degranulation. Eosinophils responded to membrane stimuli with activation of AP throughout the granules of the cell, prior to degranulation. Activation occurred within the time required for fixation of the cells by glutaraldehyde. Whereas resting normal eosinophils demonstrated AP activity in 7.8 +/- 1.2 per cent of the granules, cells stimulated with opsonized staphylococci demonstrated activity in 78.9 +/- 5.0 per cent of the granules, and the amount of lead phosphate reactant deposited per active granule was considerably more intense in the stimulated than in the unstimulated cells. A similar stimulation of AP activity in eosinophils occurred with exposure to the surface-active agent phorbol myristate acetate or the calcium ionophore A23187. Activation was not altered by 5 microgram. per ml. of cytochalasin B or 4 x 10(-6) M colchicine. These aspects of the response closely parallel the stimulation of oxidative metabolism of eosinophils; however, the two were separable. Eosinophils obtained from a patient with chronic granulomatous disease, although unable to activate the normal oxidative metabolic burst, demonstrated a normal activation of AP.

Acid Phosphatase↗
PubMed1981

Role of extracellular calcium and neutrophil degranulation responses to 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine.

The rabbit polymorphonuclear neutrophil degranulation response to 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine depends on extracellular calcium. In the absence of this bivalent cation, neutrophil suspensions pretreated with cytochalasin B responded to the lipid by releasing minimal amounts of lysozyme and beta-glucuronidase. Incremental increases in extracellular calcium over a range of 20-200 microM led to increasing amounts of lipid-stimulated enzyme release. In contrast, extracellular magnesium neither supported nor enhanced the degranulation responses. Verapamil (25-200 microgram/ml), a calcium channel blocker, inhibited degranulation. Neutrophil suspensions exposed to the phosphocholine stimulus rapidly took up radiolabeled extracellular calcium. The kinetics of this calcium uptake were similar to the kinetics of enzyme release, and the amount of calcium taken up correlated closely with the amount of released lysozyme and beta-glucuronidase. Finally, in a dosage which blocked degranulation, verapamil inhibited calcium uptake. Thus, the rapid association of extracellular calcium with the neutrophil may mediate, at least in part, the degranulating actions of the phosphocholine stimulus.

Animals↗
PubMed1981

Neutrophil-degranulating action of 5,12-dihydroxy-6,8,10,14-eicosatetraenoic acid and 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine. Comparison with other degranulating agents.

5,12-Dihydroxy-6,8,10,14-eicosatetraenoic acid was prepared from rabbit neutrophils challenged with ionophore A23187 plus arachidonic acid. It was purified by reverse-phase high-performance liquid chromatography with the use of a two-step procedure that effectively resolved the lipid from closely eluting contaminants. The phospholipid 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine was prepared from beef heart plasmalogen. Confirming earlier reports, both lipids stimulated human polymorphonuclear neutrophils to release granule-bound enzymes. Their respective degranulating actions took less than 5 minutes to become maximal, were dependent upon the presence of cytochalasin B, and required intact pathways of arachidonic acid metabolism, as judged by the inhibitory actions of arachidonate antimetabolites. Neither lipid required more than trace concentrations of extracellular calcium to effect optimal amounts of enzyme release. In one or more of these regards the two lipids differed strikingly from other neutrophil-degranulating agents such as A23187, N-formyl-methionyl-leucyl-phenylalanine, and phorbol myristate acetate. The mechanism of action of the two lipid stimuli, therefore, appear to differ somewhat from the mechanisms of the other three stimuli.

Animals↗
PubMed1981

Effects of quercetin on magnesium-dependent adenosine triphosphatase and the metabolism of human polymorphonuclear leukocytes.

The bioflavinoid quercetin was found to exert at least three separate effects on human polymorphonuclear leukocytes. (1) Concentrations of approximately 100 microM inhibited the membrane-associated magnesium adenosine triphosphatase by 60%-80% in either broken cell preparations or intact cells. Lineweaver-Burk plots showed the inhibition to be uncompetitive in nature. (2) Similar concentrations of quercetin inhibited respiratory burst activity of the cells as measured by oxygen consumption, glucose oxidation, or iodination of protein. All inhibitions were dose-dependent and were observed with either opsonized zymosan or phorbol myristate acetate as stimulus. (3) Quercetin likewise inhibited the transport of the nonmetabolizable hexose, 3H-2-deoxyglucose. These observations are most consistent with the hypothesis that quercetin exerts a generalized effect at the level of the cell membrane of the neutrophil.

Adenosine Triphosphatases↗
PubMed1981

Anaphylactic actions of platelet-activating factor.

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine) is a potent inducer of systemic anaphylactoid reactions in animals. It was found to be similarly potent in contracting smooth muscle of guinea pig ileum and lung and in enhancing vascular permeability when injected subcutaneously into these animals. This factor, therefore, possesses in vitro and in vivo bioactions that resemble those of C3a and C5a anaphylatoxins. However, platelet-activating factor induces a slowly developing, sustained contractile wave in ileum that is not inhibited by an antihistaminic compound, pyrilamine, whereas C3a and C5a stimulate rapid transient contraction that is abrogated by the antihistamine. Furthermore, platelet-activating factor desensitized the ileum to restimulation by itself but not by C3a or C5a; conversely, C3a and C5a desensitized the ileum to themselves but not to platelet-activating factor. Thus, platelet-activating factor possesses a distinctive set of anaphylactic actions. It stimulates a slow wave of muscle contraction and can act independently of histamine release and receptors for the C3a and C5a anaphylatoxins.

Anaphylatoxins↗
PubMed1981

1-O-Alkyl-sn-glyceryl-3-phosphorylcholines: a novel class of neutrophil stimulants.

1-O-Alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine aggregates and degranulates platelets and polymorphonuclear neutrophils. Here, the bioactivities of this platelet-activating factor, its 2-O-ethyl, and its 2-lyso derivatives were examined further. Each phospholipid aggregated and degranulated rabbit platelets and neutrophils with relative potencies of about 10,000 1,000, and 1, respectively. For rabbit neutrophils, and 2-O-acetyl compound was active in nanomolar and lower concentrations; required extracellular calcium and magnesium in order to induce aggregation; and required extracellular calcium and cytochlasin B in order to induce optimal degranulation. Furthermore the 2-O-acetyl and 2-O-ethyl compounds, in concentrations about tenfold higher than those required for rabbit neutrophils, aggregated and degranulated human neutrophils. With reference to these human neutrophil responses, degranulation required, and aggregation was dramatically enhanced by, cytochalasin B. The lysoanalog was unable to induce these response in the human cells. Thus, these lipids represent a novel class of neutrophil stimulants that closely resemble certain chemotactic factors (eg, C5a and synthetic oligopeptides) in their ability to aggregate and degranulate neutrophils and in the influences which calcium, magnesium and cytochalasin B have on their bioactions. Because platelet-activating factor circulates in the blood of rabbits and, perhaps, humans during anaphylaxis and is suspected of being involved in other syndromes such as serum sickness, this lipid may have unique biologic significance: it may act to recruit platelets and neutrophils into the lesions of these and similar pathologic syndromes.

Animals↗
PubMed1981

Selective desensitization of neutrophils: further studies with 1-O-alkyl-sn-glycero-3-phosphocholine analogues.

Human polymorphonuclear neutrophils aggregate and degranulate in response to 2 recently described platelet-activating phospholipids: 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine and 1-O-alkyl-2-O-ethyl-sn-glycero-3-phosphocholine. Here, we find that the 2 phospholipids can also desensitize neutrophils. Thus, cells incubated with either phosphocholine for 1 to 5 min in the absence of calcium and magnesium (which are required for aggregation) did not aggregate when exposed to the bivalent cations and fresh lipid stimulus. Also, cells incubated with either lipid for 5 min in the absence of cytochalasin B (which is required for degranulation) did not degranulate when exposed to cytochalasin B and fresh lipid stimulus. However, these desensitized neutrophils aggregated and degranulated fully in response to the chemotactic oligopeptide N-formyl-methionyl-leucylphenylalanine and C5a. In relation to the aggregation response, this selective desensitization was not due to lipid inactivation; it persisted after thorough cell washing; and it was not induced by a nonaggregating analogue, 1-O-alkyl-sn-glycerol-3-phosphocholine. Furthermore, cells desensitized to the formylated oligopeptide or C5a (by preincubation with either stimulus in the absence of bivalent cations) did not aggregate when challenged with the oligopeptide or C5a, respectively, but exhibited a normal or enhanced aggregation response to the 2 active phospholipids. These data support the concept that C5a, formylated oligopeptides, and phosphocholines represent 3 distinct classes of stimulants that activate and densensitize neutrophils by at least partially independent pathways. This activation and desensitization may be mediated by 3 types of cellular receptors, each of which interacts with only 1 class of stimuli.

Animals↗
PubMed1981

Neutrophil-aggregating activity of monohydroxyeicosatetraenoic acids.

The following oxidative derivatives of arachidonic acid were prepared and assayed for their ability to aggregate cytochalasin-B-pretreated human neutrophils: 5-, 8-, 9-, 11-, 12-, and 15-hydroxyeicosatetraenoic acids. The compounds were prepared by oxidation of arachidonic acid and purified by direct and reverse phase high performance liquid chromatography. Each lipid was racemic at the hydroxy residue and had a cistrans conjugated double bond adjacent to the hydroxy residue. Except for racemization, therefore, they were identical to hydroxyeicosatetraenoic acids generated by neutrophils exposed to diverse aggregating stimuli. In addition, 15-L-hydroxyeicosatetraenoic acid was prepared from soybean lipoxygenase. Of these 7 fatty acid preparations, only 5- and 12-hydroxyeicosatetraenoic acid aggregated the cells. Thus, the bioactions of these lipids are crucially dependent upon the position of the hydroxy residue. The 5- and 12-hydroxy derivatives were potent aggregating agents, inducing half-maximal responses at 200 and 40 nM, respectively. Their bioactions required extracellular calcium and magnesium. And the response to both fatty acids was effectively blocked by three inhibitors of cellular arachidonic acid metabolism: nordihydroguaiaretic acid, 5,8,11,14-eicosatetraynoic acid, and indomethacin. The 5- and 12- hydroxyeicosatetraenoic acids, therefore, may induce neutrophils to metabolize their endogenous arachidonate. Alternatively, the two hydroxy acids themselves may be further metabolized through pathways inhibited by arachidonate antimetabolites into a final mediator(s) of aggregate formation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1980

Oxidation of 2-deoxyglucose by human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes (PMNL) can metabolize [1-14C]2-deoxyglucose to 14CO2 when stimulated by either phorbol myristate acetate (PMA) or opsonized zymosan. Oxidation of 2-deoxyglucose is about 10-120% as efficient as that of glucose in normal PMNL; it does not occur in defective cells obtained from patients with chronic granulomatous disease. The increased oxidation of [1-14C]2-deoxyglucose induced by PMA is not sufficient to explain the inhibition of transport induced by that compound; conversely increased transport of 2-deoxyglucose induced by zymosan-activated serum does not result in a significant increase in oxidation of the hexose. Oxidation of [1-14C]2-deoxyglucose appears to be mediated by the hexose monophosphate shunt as indicated by the following (1) oxidation of [1-14C]2-deoxyglucose in intermediate in activity between that of [1-14C]glucose and [6-14C]glucose; (2) the reaction is insensitive to cyanide or azide; and (3) shunt enzymes measured in a cell-free extract from human PMNL can react with 2-deoxyglucose compounds with approximately 10% the efficiency shown towards the corresponding glucose derivatives.

Deoxy Sugars↗
PubMed1980

Role of arachidonic acid in stimulation of hexose transport by human polymorphonuclear leukocytes.

Whereas insulin does not stimulate hexose transport in polymorphonuclear leukocytes, we recently reported that C5a causes the leukocytes to take up 2-[(3)H]deoxyglucose. We now find that fMet-Leu-Phe, in a concentration-related manner with an EC(50) (concentration producing 50% of stimulatory activity) of 1.2 nM, causes a 5.5-fold stimulation of deoxyglucose uptake. Moreover, arachidonic acid (5,8,11,14-eicosatetraenoic acid) similarly stimulated deoxyglucose uptake with an EC(50) of 0.6 muM. Stimulation by arachidonic acid exhibited structural specificity; five structural analogues of arachidonic acid, including arachidonyl alcohol, 8,11,14-eicosatrienoic acid, 11,14,17-eicosatrienoic acid, 5,8,11,14-eicosatetraynoic acid, and arachidic acid, did not stimulate deoxyglucose uptake. Release and metabolism of arachidonic acid may also be involved in the stimulation of deoxyglucose uptake by fMet-Leu-Phe. Inhibitors of arachidonic acid metabolism (5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, indomethacin, aspirin, and benzylimidazole) caused parallel changes in the responses to both arachidonic acid and fMet-Leu-Phe. Stimulation of deoxyglucose uptake of polymorphonuclear leukocytes by chemotactic factors or arachidonic acid had the characteristics of carrier-facilitated hexose transport. The response was saturable with increasing concentrations of stimulant or substrate (deoxyglucose). It was stereospecific (inhibited by D-glucose but not by L-glucose) and was inhibited in resting and stimulated cells by 5 mug of cytochalasin B per ml. It was separable from the stimulation of oxidative metabolism; it occurred normally in polymorphonuclear leukocytes from a patient with chronic granulomatous disease (these are incapable of an oxidative metabolic response to membrane stimuli). Thus, stimulation of polymorphonuclear leukocytes is associated with enhanced hexose transport. Moreover, carrier-facilitated hexose transport and arachidonic acid metabolism may be linked, at least in these leukocytes: arachidonic acid mimies the stimulatory effects of chemotactic factors, and blockade of arachidonic acid metabolism inhibits the stimulation of hexose transport by these agents.

Arachidonic Acids↗
PubMed1980

Simplified neutrophil hexose monophosphate shunt assay on whole blood.

Neutrophil function was determined in resting and phagocytic cells by an assay of hexose monophosphate shunt activity performed on small volumes of whole blood. This new micromethod clearly differentiated between zymosan-stimulated and unstimulated hexose monophosphate shunt activity. Furthermore, the whole blood microassay was able to measure the large quantities of 14CO2 that previously have been measured by hexose monophosphate shunt assays performed on erythrocyte-free leukocyte preparations. Thus, because of its simplicity and accuracy, the microassay described in this report can be used for routine evaluation of those metabolic activities of neutrophils associated with phagocytosis and bactericidal activity.

Adult↗