scholarly journals Ethylene formation by polymorphonuclear leukocytes. Role of myeloperoxidase.

1978 ◽  
Vol 148 (2) ◽  
pp. 490-506 ◽  
Author(s):  
S J Klebanoff ◽  
H Rosen
Keyword(s):  
Singlet Oxygen ◽  
Hydroxyl Radicals ◽  
Superoxide Anion ◽  
Polymorphonuclear Leukocytes ◽  
Model System ◽  
Ethylene Formation ◽  
Dye Sensitized ◽  
Stimulation Of

Ethylene formation from the thioethers, beta-methylthiopropionaldehyde (methional) and 2-keto-4-thiomethylbutyric acid by phagocytosing polymorphonuclear leukocytes (PMNs) was found to be largely dependent on myeloperoxidase (MPO). Conversion was less than 10% of normal when MPO-deficient PMNs were employed; formation by normal PMNs was inhibited by the peroxidase inhibitors, azide, and cyanide, and a model system consisting of MPO, H2O2, chloride (or bromide) and EDTA was found which shared many of the properties of the predominant PMN system. MPO-independent mechanisms of ethylene formation were also identified. Ethylene formation from methional by phagocytosing eosinophils and by H2O2 in the presence or absence of catalase was stimulated by azide. The presence of MPO-independent, azide-stimulable systems in the PMN preparations was suggested by the azide stimulation of ethylene formation from methional when MPO-deficient leukocytes were employed. Ethylene formation by dye-sensitized photooxidation was also demonstrated and evidence obtained for the involvement of singlet oxygen (1O2). These findings are discussed in relation to the participation of H2O2, hydroxyl radicals, the superoxide anion and 1O2 in the formation of ethylene by PMNs and by the MPO model system.

The role of transmembrane cationic gradients in immune complex stimulation of human polymorphonuclear leukocytes

1988 ◽  
Vol 134 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Francis W. Luscinskas ◽  
Deiren E. Mark ◽  
Beatrice Brunkhorst ◽  
Fabian J. Lionetti ◽  
Edward J. Cragoe ◽  
...  
Keyword(s):  
Immune Complex ◽  
Polymorphonuclear Leukocytes ◽  
Human Polymorphonuclear Leukocytes ◽  
Stimulation Of

Use of an Improved Chemiluminescence Assay for Non-Intrusive Measurement of Hydroxyl Radicals in a Biomimetic Pulp Bleaching Model System

Holzforschung ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 181-187 ◽  
Author(s):  
C. C. Walker ◽  
R. J. Dinus ◽  
T. J. McDonough ◽  
K.-E. L. Eriksson
Keyword(s):  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Hydroxyl Radicals ◽  
Model System ◽  
Pulp Bleaching ◽  
Assay Sensitivity ◽  
Chemiluminescence Assay ◽  
Naturally Occurring ◽  
Excellent Tool

Summary A chemiluminescence assay was used to measure the production of hydroxyl radicals (·OH) in aqueous solutions of hydrogen peroxide and iron-containing catalysts. Preliminary experiments evaluating assay sensitivity revealed that one of the required reagents, phthalhydrazide (PtH), interfered with the studied reactions. In addition, undesirable degradation of the chemiluminescent form of PtH was observed. By removing PtH from reaction solutions and modifying the published procedures, a successful non-intrusive method for measurement of ·OH was obtained. The modified assay was used to compare the rate of ·OH generation in solutions of H2O2, either FeSO4 or Fe-EDTA and a substrate, lignosulfonate. This “biomimetic” pulp bleaching system is meant to simulate naturally occurring biological reactions utilized for degradation of lignins by wood-degrading fungi. Results from these experiments show that FeSO4 produced more ·OH than Fe-EDTA. The improved non-intrusive chemiluminescence assay has proven to be an excellent tool for investigating the role of the ·OH in biomimetic pulp bleaching and potentially other systems.

Endothelial dysfunction in mesenteric resistance arteries of diabetic rats: role of free radicals

1994 ◽  
Vol 266 (3) ◽  
pp. H1153-H1161 ◽  
Author(s):  
D. Diederich ◽  
J. Skopec ◽  
A. Diederich ◽  
F. X. Dai
Keyword(s):  
Nitric Oxide ◽  
Superoxide Dismutase ◽  
Free Radicals ◽  
Endothelial Dysfunction ◽  
Hydroxyl Radicals ◽  
Superoxide Anion ◽  
Diabetic Rats ◽  
Resistance Arteries ◽  
Luminal Diameter

Diabetes was induced in rats by an injection of streptozotocin (55 mg/kg). Endothelium-dependent relaxations in mesenteric resistance arteries (luminal diameter 210 +/- 20 microns) of control and diabetic rats were compared in myographs. Acetylcholine induced endothelium-dependent relaxations that were mediated by nitric oxide (EDNO). EDNO-mediated relaxations were impaired in diabetic arteries; concentrations of acetylcholine required to produce 50% relaxation (ED50) of activated arteries were 5 nM in control and 13.5 nM in arteries from diabetic rats studied after 6 wk (P < 0.05). The impairment in relaxation worsened with duration of the diabetes; ED50 for acetylcholine increased to 63 and 100 nM in diabetic arteries studied after 16 and 24 wk of diabetes, respectively. NG-nitro-L-arginine produced 5.5- and 16-fold decreases in sensitivity of control and diabetic arteries to acetylcholine. NG-nitro-L-arginine produced at least as much inhibition of acetylcholine relaxations in diabetic arteries, indicating that the impaired relaxation noted in diabetic arteries does not result from decreased production of EDNO. EDNO-mediated relaxations in diabetic arteries were impaired by increased production of endothelium-derived free radicals. Superoxide dismutase, a scavenger of superoxide anion, and dimethylthiourea, a scavenger of hydroxyl radicals, normalized EDNO-mediated relaxations in diabetic arteries. The ED50 values for acetylcholine were 13.5, 5.5, and 4 nM for untreated and SOD- and DMTU-treated diabetic arteries, respectively (P < 0.05 for treated vs. untreated arteries). Superoxide anion and hydroxyl radicals appear to block EDNO-mediated relaxation by inactivating EDNO.(ABSTRACT TRUNCATED AT 250 WORDS)

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