Search results for "N-Formylmethionine leucyl-phenylalanine"
showing 10 items of 19 documents
Hawthorn extract inhibits human isolated neutrophil functions.
2008
Hawthorn extract is a popular herbal medicine given as adjunctive treatment for chronic heart failure. In contrast to the cardiac properties of hawthorn extract, its anti-inflammatory effect has been scarcely investigated. This study examines the effects of a dry extract of leaves and flowers of Crataegus laevigata on various functional outputs of human neutrophils in vitro. Incubation of human neutrophils obtained from peripheral blood of healthy donors with C. laevigata extract (0.75-250 microg/ml) inhibited N-formyl-Met-Leu-Phe (FMLP)-induced superoxide anion generation, elastase release and chemotactic migration with potency values of 43.6, 21.9, and 31.6 microg/ml, respectively. By con…
Polymorphonuclear leukocyte membrane fluidity before and after activation in subjects with insulin resistance.
2000
The aim of this research was the evaluation of polymorphonuclear leukocyte (PMN) membrane fluidity in subjects with insulin resistance. Insulin sensitivity, in fact, may be influenced by plasma membrane fluidity. We enrolled 19 subjects with insulin resistance previously demonstrated during an euglycemic hyperinsulinemic clamp. PMN membrane fluidity was studied by labeling intact cells with the fluorescent probe 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene and calculating the fluorescence polarization degree. The measurement was made before and after incubation of PMNs with two activating agents: 4-phorbol 12-myristate 13-acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (…
Anti-Inflammatory Effects of Onions: Inhibition of Chemotaxis of Human Polymorphonuclear Leukocytes by Thiosulfinates and Cepaenes
1990
Seven different synthetic thiosulfinates, and cepaene- and/or thiosulfinate-rich onion extracts were found to inhibit in vitro the chemotaxis of human granulocytes induced by formyl-methionine-leucinephenylalanine in a dose-dependent manner and at a concentration range of 0.1–100 μ<i>M</i>. Diphenylthiosulfinate showed the highest activity and was found to be more active than prednisolone. The anti-inflammatory properties of onion extracts are related, at least in part, to the inhibition of inflammatory cell influx by thiosulfinates and cepaenes.
Diabetes mellitus: Polymorphonuclear leukocyte (PMN) filtration parameters and PMN membrane fluidity after chemotactic activation
1999
Abstract The goal of this research was to determine leukocyte rheology at baseline and after chemotactic activation in type I and type II diabetics. In 19 normal subjects, 21 type I diabetics, and 16 type II diabetics at baseline and after in vitro chemotactic activation (prolonged for 5 and 15 minutes) with two stimulating agents (4-phorbol 12-myristate 13-acetate [PMA] and N -formyl-methionyl-leucyl-phenylalanine [fMLP]), we evaluated polymorphonuclear (PMN) filtration parameters (using a St. George filtrometer [Carri-Med, Dorking, UK] and considering the initial relative flow rate [IRFR] and the concentration of clogging particles [CP]) and PMN membrane fluidity (obtained by marking PMNs…
Inhibitory effects of N-acetylcysteine on superoxide anion generation in human polymorphonuclear leukocytes.
1997
Abstract It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3–300 nm) and phorbol myristate acetate (160 pm–160 nm) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcystein…
Streptolysin O-permeabilized granulocytes shed L-selectin concomitantly with ceramide generation via neutral sphingomyelinase
2000
Abstract Cleavage of membrane-associated L-selectin regulates leukocyte rolling on vascular endothelium at sites of inflammation. We report that rapid and massive shedding of L-selectin occurs from granulocytes attacked by the pore-forming bacterial toxin streptolysin O (SLO). Shedding was not induced by an SLO mutant that retained binding capacity but lacked pore-forming activity. Cells permeabilized with SLO exhibited a 1.5-fold increase in the activity of neutral sphingomyelinase, which was accompanied by increased ceramide formation. L-selectin cleavage was inducible by treatment of cells with bacterial sphingomyelinase, and also through exogenous application of a cell-permeable ceramid…
Inhibitory effects of N-acetylcysteine on the functional responses of human eosinophils in vitro
2007
Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N-acetyl-L-cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow c…
Effects of SCA40 on human isolated bronchus and human polymorphonuclear leukocytes: comparison with rolipram, SKF94120 and levcromakalim
1996
1. SCA40 (0.1 nM-0.1 mM) produced concentration-dependent suppression of the spontaneous tone of human isolated bronchus (-log EC50 = 6.85 +/- 0.09; n = 10) and reached a maximal relaxation similar to that of theophylline (3 mM). The potency (-log EC50 values) of SCA40 compared to other relaxants was rolipram (7.44 +/- 0.12; n = 9) > SCA40 > or = levcromakalim (6.49 +/- 0.04; n = 6) > SKF94120 (5.87 +/- 0.10; n = 9). 2. When tested against the activity of the isoenzymes of cyclic nucleotide phosphodiesterase (PDE) isolated from human bronchus, SCA40 proved highly potent against PDE III (-log IC50 = 6.47 +/- 0.16; n = 4). It was markedly less potent against PDE IV (4.82 +/- 0.18; n = 4) and …
Staphylococcal alpha-toxin provokes neutrophil-dependent cardiac dysfunction: role of ICAM-1 and cys-leukotrienes.
2002
The role of polymorphonuclear neutrophils (PMN) in septic myocardial dysfunction is presently unknown. Staphylococcus aureus infections are frequently associated with septic sequelae. Therefore, we perfused isolated rat hearts with low doses of α-toxin, the major staphylococcal exotoxin, followed by application of human PMN, N-formyl-methionyl-leucyl-phenylalanine, and arachidonic acid. In contrast to sham-perfused hearts (no α-toxin), a rise in coronary perfusion pressure (CPP) and a reduction of contractile function were noted, and cardiac expression of intercellular adhesion molecule (ICAM)-1 was detected by immunohistochemical methods and real-time PCR. Histological analysis and myelope…
TNFα Primes Polymorphonuclear Leukocytes for an Enhanced Respiratory Burst to a Similar Extent As Bacterial Lipopolysaccharide
1990
We examined whether preincubating polymorphonuclear leukocytes (PMN) with TNF alpha would result in an enhanced respiratory burst upon subsequent stimulation by various agents. Bacterial lipopolysaccharide (LPS), a known primer of PMN, was used as control. We found that both LPS (0.01 to 10.0 microgram/ml) and recombinant TNF alpha (0.001 to 1.0 microgram/ml) act as direct stimulants of PMN as measured by chemiluminescence. Sixty minutes of preincubation of PMN with 1 microgram/ml TNF alpha or 10 micrograms/ml LPS resulted in similar priming for the respiratory burst elicited by opsonized zymosan, phorbol myristate acetate, zymosan, zymosan-activated serum, aggregated immunoglobulin, and f-…