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D English

Publications and source records attributed to D English.

At least 145 records · Page 8Linked to original sources
PubMed1986

Differentiation of cellular processes involved in the induction and maintenance of stimulated neutrophil adherence.

Neutrophil adherence stimulated by phorbol myristate acetate (PMA) was investigated by quantitating the attachment of 51Cr-labeled neutrophils to plastic surfaces and to the endothelium of umbilical veins mounted in compartmentalized Lucite chambers. PMA-induced adherence could be functionally separated into an induction phase requiring cellular metabolism and a Mg++ dependent maintenance phase that was independent of cellular metabolism. Thus, metabolic inhibitors (N-ethylmaleimide, 2-deoxyglucose) blocked adherence when added to neutrophils prior to PMA, but did not cause detachment of cells adhering as a consequence of prior exposure to PMA. PMA failed to induce adherence of neutrophils incubated at low (0.4 degree C) temperature, but temperature reduction, even for prolonged periods, did not cause detachment of adherent cells. Thus, the attractive forces that mediate stimulated adherence persist independently of any sustained metabolic response to the inducing stimulus. However, removal of Mg++ from the media above adherent cells resulted in immediate detachment, indicating that the cation was required for the persistent expression or maintenance of the attractive forces involved. The extent of stimulated adherence correlated well with the extent of degranulation when rates were varied by limiting the incubation time or stimulus concentration. This correlation was not absolute; in the absence of Mg++, PMA induced degranulation normally but failed to enhance adherence. To explain these findings, we investigated the possibility that PMA-stimulated adherence was maintained by Mg++-dependent cellular adherence molecules released during exocytosis. Supernatants of stimulated neutrophils were devoid of adherence-promoting activity, and only weak activity was recovered in supernatants of mechanically disrupted neutrophils. PMA effectively stimulated the tight adherence of degranulated neutrophil cytoplasts to plastic surfaces and did so in the absence of stimulated granule enzyme release. Thus, conditions have been identified under which degranulation occurs in the absence of adherence (removal of Mg++) and adherence occurs without concurrent degranulation. Since neutrophil cytoplasts do contain some granule products and granule material can be identified on cytoplast membranes, it is possible that degranulation or granule products may be involved in the adherent response. However, hyperadherence was shown to develop in the absence of de novo degranulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Adhesion↗
PubMed1985

Stimulation of neutrophil oxidative metabolism by indomethacin.

Human neutrophils exposed to indomethacin demonstrate an enhanced capacity for superoxide ion (O2-) generation when stimulated with opsonized zymosan. Enhancement is not seen with indomethacin-treated cells exposed to soluble oxidative stimuli. To further investigate this phenomenon, O2- generation, chemiluminescence, and phagocytosis were assessed in human neutrophils preincubated with indomethacin. Zymosan-stimulated O2- release was increased from 150 to 300% of controls in neutrophils exposed to 400 micrograms/ml indomethacin. Enhancement was not reversed by removal of indomethacin from the medium prior to addition of the stimulus and was dose-dependent at drug concentrations of 5 to 400 micrograms/ml. Neutrophils exposed to methacin alone also generated more O2- than control cells, although this increment was not sufficient to account for the degree of enhancement seen when indomethacin-treated cells were exposed to zymosan. Neutrophil chemiluminescence induced by zymosan was also increased by exposure to indomethacin, and at a drug concentration of 400 micrograms/ml (1.1 mM) enhancement ranged from 253 to 333% of controls. As was observed with O2- generation, chemiluminescence of neutrophils was increased in the presence of indomethacin alone, although, to a degree far less than was seen when drug-treated cells were stimulated with zymosan. Phagocytosis of radiolabeled S. aureus by neutrophils incubated with indomethacin was increased 13 +/- 5% over controls (P less than 0.01, n = 5), but was unaltered by incubation of cells with the buffer used to solubilize the drug. The modest degree of enhancement of phagocytosis suggests that increased particle uptake is not the sole mechanism of oxidative enhancement.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Synergism↗
PubMed1985

A case-control study of maternal age in Alzheimer's disease.

A case-control study of maternal age as a risk factor for Alzheimer's disease was conducted in Washington state. Clinically diagnosed cases of Alzheimer's disease (n = 64) were identified from two sources, an outpatient clinic at the University of Washington and an organization of relatives of patients with Alzheimer's disease. Controls were spouses of the Alzheimer's disease cases and spouses of 87 patients with Parkinson's disease, also identified at the University of Washington. Mail questionnaires were sent to all subjects; responses were received for 90 cases and 96 controls, although nine of those cases, whose medical records of diagnostic evaluations were incomplete, were excluded. Among the 69 cases and 94 controls whose mothers' ages were known, there was no evidence that the mothers of cases were significantly older than the mothers of controls (chi-square test for trend, P = 0.82). These findings do not support the theory that persons born to older mothers are at increased risk of developing Alzheimer's disease.

Adult↗
PubMed1985

Ascorbate in aqueous humor protects against myeloperoxidase-induced oxidation.

Chemotactic factors can cause polymorphonuclear leukocytes to release the contents of azurophilic granules, including the enzymes beta-glucuronidase and myeloperoxidase. In the presence of aqueous humor from the anterior chamber of the rabbit eye, the supernatant from stimulated leukocytes contains beta-glucuronidase, but myeloperoxidase is not detectable. Studies with aqueous humor and partially purified human myeloperoxidase suggest that this phenomenon is not due to a failure of enzyme release. The factor responsible for the inability to detect MPO in the assay system is heat-labile, dialyzable, and reversed by ascorbate oxidase. Comparable assay inhibition is produced by ascorbic acid at a concentration present in either human or rabbit aqueous humor. The ability of aqueous humor to protect against myeloperoxidase-induced oxidation may contribute to several diverse phenomena, including the susceptibility of the eye to Candida infection and a prolonged half-life for several inflammatory mediators in the anterior chamber.

Animals↗
PubMed1984

Alloxan-induced free radical production in isolated cells. Selective effect on islet cells.

Chemiluminescence, as a direct measure of oxygen free radical production, induced in isolated cells, hepatocytes, and red cells by the action of alloxan has been measured. The assay system used luminol, 3 microM, for signal amplification. The buffer used was Krebs-Ringer bicarbonate with 16 mM Hepes, pH 7.4. This buffer did not react with alloxan in the absence of cells. Some chemiluminescence was noted from all cells in the absence of alloxan. In the presence of alloxan, reactions occurred within seconds and islet cells were significantly more reactive to alloxan than either red cells or hepatocytes as defined by alloxan dose-response curves with fixed cell numbers or fixed surface areas. These data indicate a cell specificity for an early action of alloxan perhaps mediated at the cell membrane.

Alloxan↗
PubMed1984

Chemiluminescence as an index of drug-induced free radical production in pancreatic islets.

Chemiluminescence induced in isolated islets from rat pancreas by the diabetogenic drugs, alloxan and streptozotocin, has been measured. The assay system consisted of 3 microM of luminol, 10 islets, and 100 microM of alloxan or 500 microM of streptozotocin in 5 ml Krebs-Ringer bicarbonate buffer containing 16 mM of Hepes (pH 7.4). Alloxan-induced chemiluminescence appeared very rapidly and lasted more than 5 min. On the other hand, streptozotocin failed to produce chemiluminescence over a period of 60 min after addition. The presence of superoxide dismutase (1000 U/ml) and/or catalase (100 U/ml) markedly suppressed alloxan-induced chemiluminescence. These results suggest that alloxan acts as an exogenous free radical generator in pancreatic islets, but that streptozotocin does not. The involvement of superoxide anion and hydrogen peroxide in production of chemiluminescence by alloxan suggests that the hydroxyl radical may mediate this chemiluminescence.

Alloxan↗
PubMed1984

Evaluation of neutrophil labeling techniques using the chemotaxis radioassay.

Neutrophils isolated from human blood were labeled by various methods and exposed to a chemotactic gradient. The chemotactically functional cells that migrated into the gradient were isolated. The portion of radioactivity of the original cell suspension carried with the chemotactically responsive cells was related to the relative number of migrating cells as determined microscopically. Of the radionuclides used, P-32 diisopropylfluorophosphate (DFP), In-111 oxine, and Tc-99m sulfur colloid provided cell preparations with the highest relative portion of radioactivity confined to functionally intact (chemotactic) neutrophils. Results with Na2(51)CrO4 and with SnCl2-reduced 99mTcO4- were less than optimal. Neutrophils exposed to Ga-67 citrate apparently took up the label and retained chemotactic responsiveness. However, little or no radioactivity was detected in the neutrophils that migrated from the suspensions of Ga-67-labeled cells. The results indicate that the chemotaxis radioassay can yield unique information pertaining to the extent to which a radiotracer is specifically associated with viable neutrophils in a suspension of labeled cells.

Chemotaxis, Leukocyte↗
PubMed1983

Neutrophil labeling with indium-111: tropolone vs. oxine.

This study was undertaken to compare tropolone with oxine (8-hydroxy-quinoline) for labeling human neutrophils with In-111. Exposure of neutrophils to tropolone at concentrations required for efficient labeling resulted in a marked impairment of chemotaxis. In contrast, no impairment of neutrophil chemotaxis was observed using In-111 oxine. Labeling efficiencies obtained with In-111 tropolone under optimal conditions were consistently less than those obtained with In-111 oxine. We evaluated cells labeled by the two methods using chemotaxis radioassay to assess the chemotatic potential of labeled cells. The results led to the conclusion that the oxine technique is preferable to tropolone for labeling human neutrophils with In-111.

Chemotaxis, Leukocyte↗
PubMed1983

Regulation of neutrophil inflammatory mediator release: chemotactic peptide activation of stimulus-dependent cytotoxicity.

Human neutrophils stimulated with phorbol myristate acetate (PMA) were able to damage human erythroleukemic K-562 target cells as assessed by a 3-hr 51Cr-release assay. Neutrophils from a patient with chronic granulomatous disease of childhood were ineffective in mediating PMA-stimulated cytolysis. Cytotoxicity was inhibited under anaerobic conditions as well as by catalase and several free radical scavengers. Superoxide dismutase, azide, and cyanide failed to inhibit PMA-dependent cytotoxicity. The influence of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) on stimulus-dependent cytotoxicity was examined. Neutrophils preincubated with 1.0 X 10(-7) M FMLP did not display an increased cytotoxic response, but were markedly amplified in their ability to effect cytotoxicity with the addition of PMA. Enhancement of PMA-stimulated cytotoxicity resulted from a reversible cellular response to FMLP. The kinetics of the cytotoxic responses reflected the possibility that chemotactic peptide-treated neutrophils released cytotoxic mediators to a greater extent and at a faster rate than did untreated neutrophils. Although azide and superoxide dismutase did not inhibit cytotoxic responses of chemotactic peptide-activated neutrophils, the response was prevented by catalase and was markedly inhibited by several free radical scavengers. The ability of FMLP to enhance cytotoxic responses correlated well with its enhancement of PMA-stimulated chemiluminescence under a variety of conditions. In addition, the ability of PMA-stimulated neutrophils to mediate methane generation from dimethyl sulfoxide and ethylene generation from alpha keto-gamma-methiol-butyric acid (KMB)--assays that quantitate the generation of oxidizing radicals--was increased if the neutrophils were preincubated with FMLP. These results demonstrate that a chemotactic factor greatly potentiates the release of cytotoxic mediators from neutrophils upon stimulation with a nonchemotactic agent. The cytotoxic mediators appear to be products of oxidative metabolism. The cytotoxic potential of neutrophils that have responded to chemotactic stimuli to reach sites of inflammation may be activated in a similar manner.

Chemotactic Factors↗
PubMed1983

Regulation of monocyte oxidative metabolism: chemotactic factor enhancement of superoxide release, hydroxyl radical generation, and chemiluminescence.

Human peripheral blood mononuclear cells exposed to the synthetic chemotactic factor n-formyl-methionyl-leucyl-phenylalanine (FMLP) were enhanced in their ability to generate superoxide anion (O-2), hydroxyl radical (OH.), and chemiluminescence when later exposed to phorbol myristate acetate (PMA). When compared to oxidative responses of cells treated with PMA alone, the degree of enhancement by pretreatment with FMLP was 1.85-fold for O-2 generation, 1.73-fold for OH. production, and 1.34-fold for chemiluminescence. Similarly, pretreatment of mononuclear leukocytes with 5% zymosan-activated serum also enhanced subsequent oxidative responses of cells exposed to PMA. FMLP did not enhance subsequent O-2 release or chemiluminescence by mononuclear leukocytes stimulated by opsonized zymosan or 20 mM sodium fluoride (F-), demonstrating that the O-2 generating system of monocytes stimulated by phagocytosis or F- is not susceptible to chemotactic factor regulation in a manner similar to the system stimulated by PMA. The latter system, like that of neutrophils, is susceptible to regulation by cellular processes activated during an initial encounter with chemoattractants. These processes may provide a mechanism to amplify oxidative responses at sites of infection or inflammation, leading to enhanced efficiency of microbicidal activity or increased tissue damage in vivo.

Adult↗
PubMed1983

Murine eosinophils labeled with indium-111 oxine: localization to delayed hypersensitivity reactions against a schistosomal antigen and to lymphokine in vivo.

We have evaluated a method for quantitation of eosinophil migration to stimuli in vivo. Upon transfusion into normal syngeneic mice, 111In-labeled eosinophils had an intravascular half-life of 9.5 hr and distributed predominantly into spleen, bone marrow, and liver. In either Schistosoma mansoni-infected mice or recipients of lymphoid cells from infected mice, intradermal (ear pinna) injection of the schistosomal egg antigenic preparation (SEA) elicited time-dependent accumulation of 111In-labeled eosinophils detectable by either gamma scintillation counting of tissue samples or by nuclear medicine external imaging. Intradermal administration of a lymphokine fraction (containing eosinophil stimulation promoter activity) similarly caused accumulation of 111In-labeled eosinophils. Both reactions depended on the concentration of stimulus (SEA or lymphokine). 111In-labeled neutrophils or macrophages or 125I-albumin did not preferentially accumulate at the reactions examined to the extent found with 111In-labeled eosinophils, indicating that localization of label depends on an active process and is due to eosinophils rather than a contaminating cell type. The method was used to estimate how long eosinotactic lymphokine remained at dermal sites: 60% of initial activity was present 12 hr after injection. The model is discussed with regard to the role of lymphokines in hypersensitivity reactions with eosinophil involvement, such as the granulomatous response to S. mansoni eggs.

Animals↗
PubMed1982

Comparison of the effects of antioxidant non-steroidal anti-inflammatory drugs against myeloperoxidase and hypochlorous acid luminol-enhanced chemiluminescence.

The interaction of myeloperoxidase (MPO) with H2O2 and Cl- provides a potent antimicrobial/cytotoxic system for polymorphonuclear leukocytes (PMNs). MPO-related cytotoxicity may be associated with the formation of toxic oxidant MPO intermediates, HOCl, or both. MPO itself is able to oxidize drugs and cellular components. Non-steroidal anti-inflammatory drugs (NSAIDs) able to act as antioxidant free radical scavengers have recently been shown to inhibit luminol-enhanced chemiluminescence (CL) which results from the MPO-H2O2-Cl- reaction. CL is a measure of the activity of this reaction. At that time it was not clear whether the source of CL which these NSAIDs affected was HOCl or components of the initial MPO-H2O2-Cl- reaction. A NSAID antioxidant mechanism could affect MPO oxidant intermediates and HOCl. This study compares the effects of antioxidant NSAIDs, methylprednisone and free radical scavengers against MPO-based and NaOCl-based luminol-enhanced CL. Most NSAIDs which affected both MPO and NaOCl-CL appeared to share similar mechanisms, suggesting that MPO oxidant intermediates and HOCl are susceptible to NSAID effects. However, most NSAIDs were more effective against MPO-CL. The effect of these NSAIDs against MPO-CL followed the profile of NSAIDs effective in previous studies against PMN-CL. One exception to this was methylprednisone, which has no effect on PMN or MPO-CL, yet inhibited NaOCl-CL. This and other data suggest that MPO and not HOCl-related reactions are a major source of PMN-CL. Less effective NSAIDs affected NaOCl-CL better than MPO-CL. While both HOCl and MPO oxidant intermediates may be affected by NSAIDs, it appears that MPO oxidant intermediates or MPO itself are the primary target for NSAID antioxidant free radical scavenging mechanisms. These antioxidant effects impair the major killing system of the PMN and may be NSAIDs' primary anti-inflammatory mechanism. Although our data suggests the production of superoxide anion and hydroxyl radical from the MPO-H2O2-Cl- reaction, the actual presence or involvement of these free radical species is not confirmed herein.

Animals↗
PubMed1982

Antioxidation theory of non-steroidal anti-inflammatory drugs based upon the inhibition of luminol-enhanced chemiluminescence from the myeloperoxidase reaction.

The action of non-steroidal anti-inflammatory drugs (NSAIDS) has been ascribed to their ability to block the reaction of arachidonate with cyclooxygenase/peroxidase, thus inhibiting the cellular production of inflammation mediators such as prostaglandins and leukotrienes. However, this and other polymorphonuclear leukocyte (PMN) peroxidases such as myeloperoxidase (MPO) would still be capable of producing destructive oxidants which contribute to inflammation. Sulindac sulfide (Clinoril sulfide) has recently been shown to scavenge oxidant products of prostaglandin cyclooxygenase/peroxidase and MPO. The MPO-H2O2-Cl- reaction is a potent antimicrobial/cytotoxic system which produces HOCl, a strong oxidant. MPO itself has the ability to oxidize drugs and cellular components, and may be the main oxidant in PMN defenses. An antioxidant/free radical scavenger action of NSAIDs against the MPO system could be a primary mechanism of their anti-inflammatory effects. Other antioxidant/free radical scavengers have anti-inflammatory effects. MPO activity has previously been quantified using chemiluminescence (CL). In this study, NSAIDs from various classes were tested for their ability to inhibit luminol-enhanced CL from MPO. The most potent NSAIDs against MPO-CL were BW755C, phenylbutazone, indomethacin and sulindac sulfide. Salicylates and arylacetic acid derivatives, such as naproxen, also decreased MPO-CL. These drugs are also effective against CL from PMNs, of which MPO may be a main source. This effect of NSAIDs on MPO suggests that NSAIDs may impair the killing mechanism of the PMN, preventing cell destruction and release of inflammation mediators. PMN MPO appears to be a target for the antioxidant/free radical scavenging effects of NSAIDs.

Anti-Inflammatory Agents↗