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Biomedical subjects

Pier Carlo Braga

Publications and source records attributed to Pier Carlo Braga.

15 recordsLinked to original sources
PubMed2006

Effect of metabolite I of erdosteine on the release of human neutrophil elastase.

Erdosteine is a mucolytic drug whose metabolization gives rise to an active metabolite with an SH group (Met I), which reduces neutrophil release of reactive oxygen species and the peroxynitrite generated by the reaction of superoxide anion with nitric oxide, thus disrupting the phlogogenic loop sustained by activated neutrophils. Elastase, a serine proteinase released by activated human neutrophils, can degrade a wide variety of biomacromolecules including elastin and is considered to be pivotal in the pathogenesis of respiratory tract inflammation. The aim of this study was to examine whether, in addition to reducing the generation of free radicals, Met I can also interfere with the human neutrophil release of elastase. After the neutrophils were incubated with increasing amounts of Met I (1.25, 2.5, 5, 10, 20 microg/ml), elastase exocytosis was initiated by fMLP and measured using MeO-Suc-Ala-Ala-Pro-Val-MCA. The results showed that Met I significantly inhibits fMLP-induced elastase release by neutrophils in a concentration-dependent manner from 2.5 to 20 microg/ml. Our findings may be clinically relevant because the inhibitory effects were obtained at Met I concentrations that are achievable in the clinical setting. By reducing elastase and oxidant radical release (two major components of the inflammatory process), Met I have clinically useful anti-inflammatory effects.

Adult↗
PubMed2006

Anti-inflammatory activity of thymol: inhibitory effect on the release of human neutrophil elastase.

Elastase, a serine proteinase released by activated human neutrophils, can degrade a wide variety of biomacromolecules including elastin, and is considered a marker of inflammatory diseases. As the logical strategy to protect tissue is to inhibit excessive elastase activity, experimental and clinical researches have concentrated on trying to find efficient elastase inhibitors. As thymol, one of the major components of thyme oil with a phenolic structure, has been credited with a series of pharmacological properties, that include antimicrobial and antioxidant effects, the aim of this study was to explore whether it can also interfere with the release of elastase by human neutrophils stimulated with the synthetic chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP). After the neutrophils were incubated with increasing amounts of thymol (2.5, 5, 10, 20 microg/ml), elastase release was initiated by fMLP and measured using MeO-Suc-Ala-Ala-Pro-Val-MCA. The results showed that thymol inhibited fMLP-induced elastase release in a concentration-dependent manner, with the effects of 10 and 20 microg/ml being statistically significant. The behavior of cytosolic calcium mobilization revealed by fura-2 closely resembled that of elastase, thus suggesting that they may be related. The hydrophobic nature of thymol means that it can approach ion channel proteins through the lipid phase of the membrane, alter the local environment of calcium channels and thus inhibit capacitative calcium entry. In brief, thymol inactivates calcium channels machinery, thus triggering a corresponding reduction in elastase. The antibacterial and antimycotic activity of thymol is already well known, but our findings that it inhibits elastase extend our knowledge of the anti-inflammatory activity of this interesting molecule that is already credited with antioxidant activity. These two latter characteristics make thymol a molecule that can have helpful effects in controlling the inflammatory processes present in many infections.

Adult↗
PubMed2005

Antioxidant potential of thymol determined by chemiluminescence inhibition in human neutrophils and cell-free systems.

Thyme essential oil and thymol have antimicrobial, antifungal and antioxidant activities. Their antioxidant activity has been studied almost exclusively by means of chemical testing in order to be able to use it for food preservation purposes. The aim of this luminol amplified chemiluminescence (LACL) study was to investigate whether thymol can interfere with the production of reactive oxygen species, nitric oxide and the nitric oxide-derived peroxynitrite released by human neutrophils after activation by fMLP and PMA with and without the addition of the L-arginine (L-Arg) nitric oxide donor to the medium. The lowest thymol concentration that was still active in reducing LACL was 2.73 microg/ml, and there was a progressive linear inhibition of LACL from this concentration to 21.87 microg/ml, the highest thymol concentration investigated. This was also observed in the case of both fMLP and PMA stimulation with or without L-Arg. In cell-free systems using H(2)O(2)/HOCl(-) and SIN-1 as radical producers, a significant scavenging activity of thymol was present already at 0.08 and 0.68 microg/ml respectively, and these are very low concentrations. These findings can be related to the phenolic structure of thymol, because phenolic compounds have redox properties and play an important role in adsorbing and neutralizing free radicals and peroxynitrite, and in decomposing peroxides. Our findings in human neutrophils are pharmacologically relevant as they imply that thymol is a potential antioxidant and anti-inflammatory agent in human cells.

Antioxidants↗
PubMed2005

Budesonide reduces superoxide and peroxynitrite anion chemiluminescence during human neutrophil bursts.

Many lung disorders are characterized by airway inflammation involving the recruitment of inflammatory cells, and leading to the release of oxidant and inflammatory mediators. The overproduction of superoxide anion (O(2)(*-)) and nitric oxide (NO) during the respiratory bursts of neutrophils leads to production of peroxynitrite, a highly damaging oxidant with an important role in the inflammatory loop causing airway hyper-reactivity in respiratory diseases like asthma. The aim of this study was to investigate in vitro the effects of a 1-hour incubation with budesonide at 2.5 x 10(-7), 5 x 10(-7), 1 x 10(-6), 2 x 10(-6) and 4 x 10(-6) mol/l on O(2)(*-), NO, and peroxynitrite production during the respiratory burst of human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (fMLP, 5 x 10(-7) mol/l) or phorbol 12-myristate 13-acetate (PMA, 2 x 10(-6) mol/l), as documented by luminol-amplified chemiluminescence (LACL). In absence of L-arginine, budesonide (5 x 10(-7) to 4 x 10(-6) mol/l) dose-dependently reduced both fMLP- and PMA-induced LACL (18.3-50.6%). In the presence of L-arginine (100 microg/ml), a NO donor increasing peroxynitrite production, LACL increased 3-5 times compared with baseline, but budesonide dose-dependently reduced LACL (25.5-59.6%). Mifepristone (4 x 10(-6) mol/l), a glucocorticoid receptor antagonist, inhibited the effect of budesonide on LACL, thus confirming that budesonide reacts with glucocorticoid receptors to exert an antioxidant activity. These results suggest that budesonide target rapidly human neutrophils leading to a fast reduction in both NO and peroxynitrite production, and are consistent with decrease in exhaled NO levels after treatment with budesonide in patients with asthma.

Anti-Inflammatory Agents↗
PubMed2005

A combination of budesonide and the SH-metabolite I of erdosteine acts synergistically in reducing chemiluminescence during human neutrophil respiratory burst.

Activated neutrophils can release superoxide anion and nitric oxide (NO), which subsequently combine with each other to yield peroxynitrite anions, powerful and harmful oxidants that preferentially mediate the oxidation of the thiol groups in proteins and non-protein molecules. These oxidants play a direct role in the inflammatory process in chronic obstructive pulmonary disease and asthma by increasing the number of neutrophils and macrophages that induce a self-sustaining phlogogenic loop. Budesonide (BUD) and erdosteine (a muco-active drug which, after metabolization, produces an active metabolite (Met I) with a sulfhydryl group) are both active in reducing the release of superoxide anion, NO and peroxynitrite, and can be administered to patients with respiratory diseases. The aim of this study was to investigate the possible synergistic in vitro effect of BUD and Met I on chemiluminescence generation during fMLP-stimulated respiratory bursts of human neutrophils with the NO donor L-arginine, added to the incubating medium. The investigated BUD concentrations ranged from 6 x 10(-8) to 1 x 10(-6) mol/l in logarithmic scale and a significant and progressive reduction in luminol-amplified chemiluminescence (LACL) was observed at concentrations ranging from 2.5 x 10(-7) to 1 x 10(-6) mol/l. The investigated concentrations of Met I varied from 0.62 to 10 microg/ml. No significant changes were observed at 0.62, 1.25, and 2.5 microg/ml, but a significant decrease in LACL was observed at 5 and 10 microg/ml. When the two drugs were combined, there was a greater significant decrease in LACL versus the single drugs with the combinations of BUD 1 x 10(-6) mol/l plus Met I 10 microg/ml, BUD 5 x 10(-7) mol/l plus Met I 5 microg/ml, BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml, and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml. A further interesting finding was that the combination of BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml significantly decreased LACL, whereas the single concentrations had no significant effect, thus indicating the possibility of extending the duration of the effect. Our findings indicate a synergistic antioxidant effect when BUD and Met I are given together, which is of interest for counteracting the airway phlogosis involved in many respiratory diseases.

Anti-Inflammatory Agents↗
PubMed2004

Inhibitory effects of metabolite I of erdosteine on the generation of nitric oxide and peroxynitrite chemiluminescence by human neutrophils.

Polymorphonuclear neutrophils (PMNs) can generate superoxide anions and nitric oxide (NO), which is not only an important mediator of various cellular activities, but can also react with superoxide anions to produce peroxynitrite anions (ONOO-). Peroxynitrite is a potent and potentially toxic oxidant that damages various types of biomolecules. It preferentially mediates the oxidation of thiolic groups in protein and non-protein molecules, thus altering their functions. The aim of this study was to examine whether, in addition to its ability to reduce the respiratory bursts of human PMNs, the SH metabolite I (Met I) of erdosteine, can interfere with NO and NO-derived peroxynitrite production, thus extending its antioxidant activity. This was done by means of the luminol amplified chemiluminescence (LACL), which has been widely used to detect the production of reactive oxidant species (ROS) by PMNs under various conditions. At 5 and 10 microg/ml, Met I significantly reduced LACL after fMLP and PMA stimulation. When L-Arg was added to the reaction medium, as a NO donor, the chemiluminescence of fMLP increased by up to 67% and that of PMA by up to 132%, but was once again significantly reduced by 5 and 10 microg/ml of Met I. In a cell-free system, the use of linsidomine (SIN-1) makes it possible to investigate the behavior of LACL induced by peroxynitrite release, which was significantly reduced by Met I concentrations ranging from 1.25 to 10 microg/ml. Our findings indicate that Met I, a molecule with a SH group, reacts with ROS, NO and NO-derived peroxynitrite, and has both antioxidant and scavenging activity. This is of interest for the strategy of protecting against damage induced by radical species in the pulmonary cell environment, in which they can induce a phlogogenic loop, and suggests that adding exogenous thiols may be useful in antagonizing the toxic effects of reactive molecules on endogenous thiols.

Adult↗
PubMed2003

Flow cytometric assessment of susceptibilities of Streptococcus pyogenes to erythromycin and rokitamycin.

The effects of erythromycin (a 14-membered ring macrolide) and rokitamycin (a 16-membered ring macrolide) on the viability of the Streptococcus pyogenes M phenotype were studied by means of flow cytometry and fluorescence microscopy by using a combination of two fluorochromes (syto 9 and propidium iodide) that stains live bacteria green and dead bacteria red. In order to apply the flow cytometry, a bacterial sonication procedure was expressly set up to separate single cells from the long, intralaced S. pyogenes chains of up to 30 to 40 cells that have previously prevented the application of flow cytometry to this type of bacteria. The association of flow cytometry using an appropriate sonication procedure, together with a combination of fluorescent probes, offered the possibility of very quickly investigating the different microbiological effects of rokitamycin at 2 microg/ml, which was active on the S. pyogenes M phenotype, and of erythromycin at doses of up to 32 microg/ml, which was not.

Erythromycin↗
PubMed2003

Effect of butylated hydroxyanisole and some of its derivatives on human neutrophil oxidative burst: chemiluminescence evaluation.

An acute inflammatory response begins during the reperfusion phase following an ischemic insult in which polymorphonuclear neutrophils (PMNs) play an important role and the release of reactive oxygen species (ROS) causes further damage and a reduction in endogenous antioxidant storage. The ability of butylated hydroxyanisole (BHA) and some phenolic, aliphatic and aromatic BHA derivatives to reduce the human PMN oxidative burst evoked by particulate (Candida albicans and zymosan) or soluble stimulants [N-formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA)] was investigated using luminol-amplified chemiluminescence. BHA and the derivative dt-BHA [3,5-di-t-butyl-4-hydroxyanisole] significantly reduced the PMN oxidative burst at concentrations ranging from 5 x 10(-6) to 5 x 10(-5) mol/l for C. albicans stimulation, while for zymosan stimulation, reduction was seen at concentrations ranging from 5 x 10(-6) to 5 x 10(-5) mol/l for BHA, and at concentrations ranging from 5 x 10(-7) to 5 x 10(-5) mol/l for dt-BHA, with dt-BHA being the most active. Another BHA derivative, Bu GAM 1, was active at 5 x 10(-5) mol/l for C. albicans and at 5 x 10(-6) to 5 x 10(-5) mol/l for zymosan. The findings obtained with fMLP and PMA were very similar to those previously reported. ROS release is related to PMN killing activity, but the inhibition of the PMN oxidative burst induced by BHA and BHA derivatives did not significantly modify PMN phagocytosis or killing. It has recently been observed that dt-BHA has a spasmolytic action by inhibiting the influx of Ca(2+) into cells through L-type Ca(2+) channels, which means that a single molecule is capable of counteracting two major steps in the sequence of events triggered by ischemia-reperfusion injury, i.e. free radical release and Ca(2+) overload.

Adult↗
PubMed2002

Effects of sub-minimum inhibitory concentrations of gatifloxacin on the inhibition of Staphylococcus aureus and Escherichia coli adherence.

The aim of this study was to investigate the capacity of subinhibitory concentrations of the newly developed fluoroquinolone antibiotic gatifloxacin (CAS 160738-57-8) to interfere with the mechanism of bacterial adhesion. Human buccal epithelial cells were incubated with different strains of both Staphylococcus aureus and Escherichia coli, grown in the presence of subinhibitory gatifloxacin concentrations varying from 1/2 MIC (minimum inhibitory concentration) to 1/128 MIC. A significant decrease was observed in the adherence of S. aureus and E. coli to buccal cells at drug MICs of 1/2 to 1/32 and 1/2 to 1/64, respectively. A large number of filamentous forms of different lengths and shapes were observed in the case of E. coli, whereas there was an abnormal increase in the diameter of the cells in the case of S. aureus. The interpolation of these pharmacodynamic findings with the pharmacokinetic curve indicate that the effect of subinhibitory concentrations of gatifloxacin can prolong its antimicrobial effects against S. aureus and E. coli for as long as 30 h and 37 h, respectively, after the MIC values have been reached.

Anti-Infective Agents↗
PubMed2002

Human neutrophil oxidative bursts and their in vitro modulation by different N-acetylcysteine concentrations.

Reactive oxygen species released by activated polymorphonuclear leukocytes as an expression of their defensive function are considered to be a major source of the cytotoxic oxidant stress, that triggers a self-sustaining phlogogenic loop in the respiratory system. N-Acetylcysteine (CAS 616-91-1, NAC), a known mucolytic drug, possesses also antioxidant properties, but it undergoes a rapid and extensive first-pass metabolism resulting in low tissue availability. Thus to further improve the NAC bioavailability a single oral administration of 1200 mg NAC has been recently proposed. This study has been performed to investigate in vitro by means of luminol amplified chemiluminescence the ability of the concentration of 35 mumol/l NAC available after single oral administration of 1200 NAC to interfere with human neutrophil oxidative burst evoked by both corpuscolate and soluble stimulants, in comparison with 16 mumol/l NAC, the serum concentration obtainable after single oral administration of 600 mg NAC. At concentrations of 16 and 35 mumol/l, NAC significantly reduced in a concentration-dependent manner the activation of polymorphonuclear neutrophils (PMNs) oxidative bursts induced by all of the stimulants (C. albicans, formyl-methionyl-leucyl-phenylalanine (fMLP), phorbol myristate acetate (PMA)). This effect was also present in cell-free systems, thus confirming the scavenger activity of these two concentrations of NAC. The fact that no effects were seen on PMN phagocytosis and bacterial killing indicates that NAC has no negative influence on other PMN functions such as antimicrobial activity.

Acetylcysteine↗
PubMed2002

Differences in the susceptibility of Streptococcus pyogenes to rokitamycin and erythromycin A revealed by morphostructural atomic force microscopy.

The aim of this study was to use atomic force microscopy (AFM), an innovative type of microscopy, to investigate the different behaviours of erythromycin A (a 14-membered ring) and rokitamycin (a 16-membered ring) in disrupting the morphology of Streptococcus pyogenes with the M phenotype. AFM scanning and sensing of the topography of a sample makes it possible to obtain simultaneous high-resolution digital measurements of the x, y and z coordinates at any point on the bacteria surface. The images obtained before and 2, 4 and 6 h after incubation with erythromycin A (32 mg/L) and rokitamycin (2 mg/L) clearly show that not even high concentrations of erythromycin A interfere with the M phenotype of S. pyogenes, whereas rokitamycin has a progressive action that leads to the formation of abnormally large cells, the loosening of chain structure and the formation of clusters.

Drug Resistance, Bacterial↗