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Biomedical subjects

M P Terrón

Publications and source records attributed to M P Terrón.

6 recordsLinked to original sources
PubMed2006

Hydrogen peroxide increases the phagocytic function of human neutrophils by calcium mobilisation.

We have studied the effect of exogenous administration of hydrogen peroxide (H(2)O(2)) on phagocytic activity of human neutrophils. The treatment of cells with increasing concentrations of H(2)O(2) evoke a significant elevation of phagocytic function assayed as phagocytic index, percentage and efficiency; and was similar to that induced by the calcium mobilising agonist formyl-methionyl-leucyl-phenylalanine (fMLP). This stimulatory effect was reduced by pre-treatment of neutrophils with catalase and abolished in neutrophils loaded with the intracellular calcium quelator dimethyl BAPTA. In the absence of extracellular calcium, treatment of cells with H(2)O(2) resulted in a increase in [Ca(2+)]( i ), indicating the release of calcium from intracellular stores. H(2)O(2) abolished the typical calcium release stimulated by the physiological agonist fMLP, while depletion of agonist-sensitive calcium pools by fMLP was able to prevent H(2)O(2)-induced calcium release. We conclude that H(2)O(2) induces calcium release from agonist-sensitive stores and consequently increase the phagocytosis process.

Adolescent↗
PubMed2005

Melatonin, lipid peroxidation, and age in heterophils from the ring dove (Streptopelia risoria).

Numerous recent studies have shown the ability of physiological as well as all pharmacological concentrations of melatonin to prevent oxidative stress. We have found that incubating avian heterophils from young birds with a pharmacological concentration of 100 microM (23x10(6) pg/ml) melatonin reduced superoxide anion levels by modulating the activity of superoxide dismutase while also enhancing phagocytosis. There was also a decline in lipid peroxidation levels with both physiological and pharmacological concentrations of this indolamine. In the present work, we evaluated malonaldehyde (MDA) levels as an indicator of lipid peroxidation (both basal and antigen-induced) in young and old animals (ring doves) at different times of day (16:00 and 00:00) and with two incubation times (15 and 60 min). The lipid peroxidation was also measured in heterophils from old animals, incubated with the physiological concentrations of melatonin measured in young animals (50 and 300 pg/ml, diurnal and nocturnal, respectively). The results, expressed as nmol MDA/mg protein, show that MDA levels were higher in heterophils of old animals than in the young birds in all the experimental groups studied at both 16:00 and 00:00 (00:00 is the time at which the lowest peroxidation levels were obtained). Incubation with melatonin was found to reduce MDA levels, with the maximum reduction being after the 60?min incubation time and the nocturnal melatonin concentration. At both concentrations (diurnal and nocturnal), melatonin also counteracted the enhancement of MDA levels caused by latex beads, with the effect being greater at the longer incubation time. In conclusion, the results are further evidence of the antioxidant effect of melatonin even at physiological concentrations, and suggest its utility as a therapeutic agent in some pathological processes associated with age.

Aging↗
PubMed2004

Comparative study of the heterophil phagocytic function in young and old ring doves (Streptopelia risoria) and its relationship with melatonin levels.

A functional connection between the pineal gland (via the hormone melatonin) and the immune system has been suggested. In our previous results in the ring dove, we observed diurnal oscillations in the levels of this neurohormone in young animals and a decline in its plasma levels with advancing age (which is accompanied by the absence of diurnal rhythm). We also noted enhanced phagocytic activity of heterophils from old animals after in vitro incubation with both physiological and pharmacological doses of melatonin. Here, we evaluate the functional capacity of ring dove (Streptopelia risoria) heterophils in young (2 years of age) and old (8 years and more) animals at different times of day (0:00, 10:00 and 16:00, the times when the maximum, minimum, and mean values, respectively, of melatonin levels are observed in young animals). The phagocytic capacities for the ingestion of latex beads and Candida albicans were evaluated, as well as the oxidative metabolism which accompanies phagocytosis. At all three times of day studied, the heterophil phagocytic function with both latex and C. albicans was significantly greater in the young than in the old animals, and in the young animal cells it was significantly higher at 0:00. In addition, in the presence of latex beads, there was a significant decline at 10:00 and 0:00 of superoxide anion levels in the young animals relative to the old. In the young animals, there was a decline at 0:00 in comparison with both 10:00 and 16:00, and in the old animals there was a decline at both 0:00 and 16:00 compared with 10:00. These results could be due, at least in part, to the absence of a diurnal rhythm of melatonin in old animals, and to an enhancing effect of that hormone on young animals' heterophil phagocytic function, which would also neutralize the oxidative stress deriving from this immune function.

Age Factors↗
PubMed2003

Phagocytosis of Candida albicans and superoxide anion Levels in ring dove (Streptopelia risoria) heterophils: effect of melatonin.

We observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased the phagocytosis of inert particles (latex beads), and also provoked a decline in superoxide anion levels of those phagocytes. In the present study, we wanted to corroborate whether melatonin acts on the oxidative metabolism that accompanies the respiratory burst during phagocytosis by inducing a more effective phagocytic activity at the same time as exerting an antioxidant effect to eliminate and/or scavenge the free radicals left over after the destruction of the foreign material. To this end, we evaluated the ingestion and destruction of Candida albicans (live particles) by ring dove (Streptopelia risoria) heterophils after different times of incubation (30 and 60 min) with physiological concentrations of melatonin (50 pg/ml diurnal and 300 pg/ml nocturnal), as well as with a pharmacological concentration 23 x 106 pg/ml (100 micro m) of the hormone. In parallel, using the same times of incubation, we evaluated the oxidative metabolism by determining the superoxide anion levels (O2-.). The results show that melatonin, at all the times and concentrations studied, increases both the phagocytosis index (number of C. albicans phagocytosed by 100 heterophils) and the candidicide power (percentage of C. albicans killed of those ingested by 100 heterophils). The effect was dose-dependent. With respect to the oxidative metabolism accompanying the digestion and destruction, there was a decline in superoxide anion levels after incubation with all of the concentrations of the hormone studied. The effect was dose-dependent and most pronounced at 60 min. These results thus corroborate the proposal that melatonin enhances the phagocytic function at the same time as neutralizing the oxidative stress derived from this immune function.

Animals↗
PubMed2001

Physiological concentrations of melatonin and corticosterone affect phagocytosis and oxidative metabolism of ring dove heterophils.

A functional connection between the neuroendocrine and the immune systems has been established. Of particular interest is the finding that hormones such as melatonin and corticosterone are able to exert modulating effects on the immune function. Therefore, after determining the circadian rhythms of melatonin and corticosterone, we evaluated the in vitro effect of physiological concentrations of melatonin and corticosterone, separately and together, on the phagocytic function and superoxide anion levels of heterophils in ring dove (Streptopelia risoria). Trials were performed with concentrations corresponding to the nocturnal and diurnal levels reached by each of the hormones (50:300 pg/mL and 100:10 ng/mL for melatonin and corticosterone, diurnal:nocturnal, respectively). The phagocytes were incubated with the hormones both alone and concurrently. At the highest (nocturnal) concentration, melatonin augmented phagocytic function and at the same time inducing a fall in superoxide anion levels. At the highest (diurnal) concentration, corticosterone also enhanced phagocytic function, but without modifying the phagocyte oxidative metabolism. In the presence of both hormones, however, whether with nocturnal or diurnal concentrations, there was a greater increase in phagocytic function and a decrease in superoxide anion levels than was produced by either of the hormones alone. In conclusion, our findings suggest that melatonin and corticosterone may have an additive effect in the modulation of phagocytic function.

Animals↗