Search PubMed⌕ Search

Biomedical subjects

A B Rodríguez

Publications and source records attributed to A B Rodríguez.

At least 19 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↗
PubMed2006

L-tryptophan administered orally at night modifies the melatonin plasma levels, phagocytosis and oxidative metabolism of ringdove (Streptopelia roseogrisea) heterophils.

The essential amino acid tryptophan is the precursor in the anabolic pathway of melatonin, a hormone with immunomodulatory properties. The present study shows the in vivo effect of tryptophan on the phagocytic function and oxidative metabolism of heterophils from Streptopelia roseogrisea of < 1 year of age, with a parallel evaluation of the plasma levels of melatonin. The L-tryptophan was administered orally (125 and 300 mg/kg b.w.) at 19:00, before the beginning of the period of darkness, for 7 days. At the end of the tryptophan treatment, determinations were made at 21:00 and 02:00 of the Phagocytosis Index, the Phagocytosis Percentage, the Phagocytic Efficiency and the superoxide anion levels in heterophils isolated from blood and of the plasma levels of melatonin. The results showed, for the determinations at 21:00 in the animals that had received 125 mg L-tryptophan/kg b.w., enhanced heterophil phagocytic function and raised levels of plasma melatonin, with no affect on the oxidative metabolism of the phagocytes. For the administration of the greater concentration of tryptophan (300 mg/kg b.w.), there were raised plasma melatonin levels together with increases in heterophil phagocytic capacity and phagocyte oxidative metabolism at 02:00. The results indicate that tryptophan administered orally at night to diurnal animals of less than 1 year in age affects the circulating levels of melatonin at the same time as inducing stimulation of the innate immune function.

Administration, Oral↗
PubMed2006

Synthesis, structural characterization and influence on the phagocytic activity of human neutrophils of thiazoline and thiazine derivative ligands and their zinc(II) complexes.

The zinc(II) complexes dichloro[2-(3,4-dichlorophenyl)imino-kappaN-(2-thiazolin-kappaN-2-yl)thiazolidine]zinc(II) (1) and dichloro[2-(3,4-dichlorophenyl)imino-kappaN-(4H-5,6-dihydro-1,3-thiazin-kappaN-2-yl)tetrahydrothiazine]zinc(II) (2) have been isolated and characterized in the solid state by X-ray diffraction, elemental analysis and IR spectra. In both complexes, the environment around the zinc(II) ion may be described as a distorted tetrahedral geometry, with the metallic atom coordinated to two chlorine atoms [Zn-Cl(1)=2.218(1)A; Zn-Cl(2)=2.221(1)A], one imino nitrogen [Zn-N(3)=2.042(2)A] and one thiazoline nitrogen [Zn-N(1)=2.022(2)A] in complex 1 and to two chlorine atoms [Zn-Cl(1)=2.216(1)A; Zn-Cl(2)=2.192(1)A], one imino nitrogen [Zn-N(3)=2.045(2)A] and one thiazine nitrogen [Zn-N(1)=2.039(2)A] in complex 2. In addition, we also report in this study the crystal structure of the 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn) ligand as well as the synthesis and characterization by X-ray diffraction, (1)H and (13)C NMR spectra, elemental analysis, IR and electronic spectra of the 2-(3,4-dichlorophenyl)imino-N-(4H-5,6-dihydro-1,3-thiazin-2-yl)tetrahydrothiazine (TzTz) ligand. Besides, we study the phagocytic function in humans neutrophils treated with each complex and ligand aforementioned.

Crystallography, X-Ray↗
PubMed2006

Improved circadian sleep-wake cycle in infants fed a day/night dissociated formula milk.

On the basis of the circadian nutritional variations present in breast milk, and of the implications for the sleep/wake cycle of the nutrients present in infant formula milks, we designed a formula milk nutritionally dissociated into a Day/Night composition. The goal was to improve the bottle-fed infant's sleep/wake circadian rhythm. A total of 21 infants aged 4-20 weeks with sleeping difficulties were enrolled in the three-week duration study. The sleep analysis was performed using an actimeter (Actiwatch) placed on an ankle of each infant to uninterruptedly record movements during the three weeks. The dissociated Day milk, designed to be administered from 06:00 to 18:00, contained low levels of tryptophan (1.5g/100g protein) and carbohydrates, high levels of proteins, and the nucleotides Cytidine 5 monophosphate, Guanosine 5 monophosphate and Inosine 5 monophosphate. The dissociated Night milk, designed to be administered from 18.00 to 06.00, contained high levels of tryptophan (3.4g/100g protein) and carbohydrates, low levels of protein, and the nucleotides Adenosine 5 monophosphate and Uridine 5 monophosphate. Three different milk-feeding experiments were performed in a double-blind procedure covering three weeks. In week 1 (control), the infants received both by day and by night a standard formula milk; in week 2 (inverse control), they received the dissociated milk inversely (Night/Day instead of Day/Night); and in week 3, they received the Day/Night dissociated formula concordant with the formula design. When the infants were receiving the Day/Night dissociated milk in concordance with their environment, they showed improvement in all the nocturnal sleep parameters analyzed: total hours of sleep, sleep efficiency, minutes of nocturnal immobility, nocturnal awakenings, and sleep latency. In conclusion, the use of a chronobiologically adjusted infant formula milk seems to be effective in improving the consolidation of the circadian sleep/wake cycle in bottle-fed infants.

Bottle Feeding↗
PubMed2005

Effect of the preventive-therapeutic administration of melatonin on mammary tumour-bearing animals.

Melatonin has been reported to be involved in the feedback between neuroendocrine and immune functions and to exert oncostatic actions. Likewise, this hormone seems to lengthen life span in healthy animals. As of present, most studies have analysed the therapeutic effect of melatonin on cancer growth, but few have tested the preventive effect of melatonin in reducing the risk of cancer. Thus, the aim of this study was to evaluate the preventive-therapeutic effects of melatonin on rats with DMBA-induced mammary tumours, and to examine the effect of melatonin on the first line of cell defence against cancer (macrophages and NK cells) and on some of the neuroendocrine factors that are involved in the development of tumours (prolactin and catecholamines). Melatonin treatment (5 mg/day/animal) began one month prior to DMBA (9,10-dimethyl-1,2-benzanthracene) administration to females Sprague Dawley rats. It was found that the treatment led to an increase in survival and in latency time in the tumour-bearing rats. Although the melatonin treatment did not influence either the phagocytic capacity of macrophages or the number of peripheral blood NK cells, it did stabilise the levels of prolactin by returning the concentrations of this hormone to those of the healthy animals. We conclude that melatonin can exert an oncostatic action, lengthening the survival time of mammary tumour-bearing animals, and suggest that this effect is due, at least in part, to regulating the neuroendocrine parameters of tumour-bearing animals, bringing them closer to their optimal physiological status.

Adjuvants, Immunologic↗
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↗
PubMed2005

The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn.

INTRODUCTION: The hormone melatonin regulates the sleep and this pineal hormone is synthesized in the organism from the amino acid tryptophan. It is known that breast-fed babies have better sleep patterns and a better entrained sleep/wake cycle than bottle-fed babies (adapted formula). OBJECTIVE: To compare the circadian rhythm of 6-sulfatoxymelatonin (aMT6s)--the metabolite of melatonin excreted in the urine--in urine of bottle-fed and breast-fed children, and relate it to the circadian rhythm of tryptophan in breast milk, also evaluating the possible effects on the baby's night-time rest. METHODS: 16 infants of 12 weeks of age were studied, divided into two groups depending on their exclusively natural or artificial feeding. The circadian rhythm of 6-sulfatoxymelatonin in urine was measured for the two groups of infants and for the breast-feeding mothers. In the breast milk, the circadian rhythm of the amino acid tryptophan was measured. The rest of the infants was tested by wrist actimeters for a week and the sleep parameters of the infants were measured and evaluated. RESULTS: The tryptophan in the breast milk presented a circadian rhythm with acrophase at around 03:00. This affected the 6-sulfatoxymelatonin circadian rhythm with acrophase at 06:00 in the breast-fed infants, and also promoted nocturnal sleep. Assumed sleep, actual sleep, and sleep efficiency were significantly increased in the breast fed infants with respect the formula fed infants. CONCLUSION: A temporal relationship was observed between the circadian rhythm of 6-sulfatoxymelatonin of the exclusively breast-fed babies and that of tryptophan in the mother's milk. Acting this amino acid as a zeitgeber entrainment of the biological rhythms in the breast-fed infant.

Bottle Feeding↗
PubMed2004

Norepinephrine as mediator in the stimulation of phagocytosis induced by moderate exercise.

During intensive exercise the stimulation of phagocytosis is mediated by "stress hormones". During moderate exercise, however, such mediation is less clear. The influence of moderate exercise (45 min at 55% maximal oxygen uptake) on the phagocytic capacity of neutrophils was evaluated in sedentary men. The exercise stimulated phagocytosis of Candida albicans, and the stimulation was maintained for at least 24 h. The possible neuroendocrine mediators were then investigated. Stimulation of phagocytosis was found after incubating neutrophils from sedentary individuals, who were in a basal state, with plasma from exercised individuals. Immediately after exercise, there was a significant increase in the concentration of norepinephrine, but not of epinephrine or cortisol. Incubation of neutrophils with this post-exercise physiological concentration of norepinephrine also stimulated phagocytosis, and the effect was blocked by both propranolol and phentolamine. The norepinephrine-augmented phagocytosis was accompanied by an increase in intracellular levels of cAMP, but not of cGMP or calcium. In conclusion, moderate exercise performed by sedentary people stimulates the phagocytic capacity of neutrophils, and the stimulation lasts for at least 24 h. Norepinephrine mediates the stimulation, although other mechanisms could be involved during the recovery period.

Adult↗
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↗
PubMed2002

In-vitro study of the effect of adrenaline on the functional capacity of human neutrophils: role during exercise.

We studied the effect of adrenaline on the capacity of human neutrophils to attach, ingest and destroy Candida albicans. The neutrophils were incubated in vitro in the presence of an adrenaline concentration taken as basal (10-10 m), and another that is referred to as being reached following physical exercise (10-9 m). Two higher concentrations (10-7 m and 10-5 m), which are seldom attained in blood but which can occur at specific locations in the organism, were tested as having a possible pharmacological application. At the two high concentrations (10-7 m and 10-5 m), the capacity to attach, ingest and destroy C. albicans was greater than at the physiological concentrations (10-10 m and 10-9 m). Indeed, the capacity to attach and ingest C. albicans was significantly less after incubation with these physiological concentrations than the control values (incubation in the absence of adrenaline). Hence, high concentrations of adrenaline seem to enhance neutrophils' phagocytic capacity compared to physiological plasma concentrations, whereas small variations such as those caused by physical exercise have no effect on this functional capacity.

Adolescent↗
PubMed2001

Circadian rhythm of melatonin, corticosterone and phagocytosis: effect of stress.

Melatonin has a functional connection with the immune system. Phagocyte function is altered by extirpation of the pineal gland, one source of melatonin, or by in vitro incubation of phagocytes with pharmacological concentrations of melatonin. Given that its synthesis by pinealocytes is under the control of the noradrenaline released by the sympathetic postganglionaric nerve endings, the present work was aimed at evaluating the circadian rhythm of melatonin, corticosterone, and phagocytosis in BALB/c mice in basal and stress situations. Peritoneal macrophages were used as phagocytes, latex beads as the particles to be ingested, and forced swimming to exhaustion as the stress situation. Radioimmunoassay was used to determine the animals' serum hormone levels. Samples were taken every 3 hr in the period from 04:00 to 22:00 hr, and every 30 min during the remaining period from 22:00 to 04:00 hr. Control mice presented a short-term melatonin peak at 23:30 hr, while the maximum inert-particle ingestion capacity of the peritoneal macrophages also occurred during the night but at 03:30 hr. The corticosterone levels in control mice presented a circadian rhythm with a day-time maximum peak (16:00 hr). Compared with the controls, the animals subjected to stress maintained, although at lower values, the melatonin peak at 23:30 hr, but they presented a loss of the rhythm of serum corticosterone levels, and the corticosterone levels and the macrophage phagocytic capacity were greater at all hours of the day.

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↗
PubMed2001

Phagocytic function in cyclists: correlation with catecholamines and cortisol.

Flow cytometer measurements were made of the basal variations in peripheral blood functional monocytes and granulocytes over the course of a training season (January to November) of a cycling team. Parallel determinations were made of plasma concentration of catecholamines (chromatography) and cortisol (RIA) in a search for neuroendocrine markers. The results showed the greatest phagocytic capacity to occur in the central months (March, May, and July), coinciding with the greatest number and highest level of competitive events with good correlation with a peak in epinephrine during these months (r(2) = 0.998 for monocytes and r(2) = 0.674 for granulocytes). No good correlations were found between phagocytosis and norepinephrine or cortisol. The highest values for phagocytosis and epinephrine concentration were found in May. These results suggest that blood epinephrine concentration could be a good neuroendocrine marker of sportspeople's phagocytic response.

Adult↗
PubMed1999

Parenteral infusions bacterial contamination in a multi-institutional survey in Mexico: considerations for nosocomial mortality.

BACKGROUND: Parenteral infusions can be contaminated during administration (extrinsic contamination). A previous survey found that extrinsic contamination was not uncommon in a hospital in Mexico with lapses in aseptic techniques. To determine whether this problem exists in other similar institutions, we undertook a multi-institutional study. METHODS: We surveyed 6 hospitals (A to F) lacking an infection control committee to determine the level of extrinsic contamination. We visited each hospital and obtained samples of all the parenteral infusions in use, drawing 0.5-1 mL from the tubing injection port. Quantitative and qualitative bacterial cultures were performed. Chlorine levels of the tap water were measured. Visits were repeated until the survey was completed. RESULTS: A total of 751 infusions were cultured, of which 16 (2.13%) were contaminated. Hospital contamination rates varied from zero to 5.56%. Klebsiella pneumoniae was the most common isolate (10 cases). During the first sampling day in hospital C, the 7 infusions from the pediatric ward were found to be contaminated with a similar K pneumoniae strain. In-service education was started in this hospital. Infusion contamination was eliminated followed by a reduction in mortality rate. Overall, a higher risk for infusion contamination was noted for pediatric patients (P =.01, odds ratio = 3.28, 95% CI, 1.10-9.91) and in wards with inadequate water chlorine levels (P =. 02, odds ratio = 3.64, 95% CI, 1.08-13.51). CONCLUSIONS: If the hospitals surveyed are representative of others in developing countries, an endemic level of parenteral infusion contamination could exist in many hospitals throughout the world.

Adult↗
PubMed1999

Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils.

A functional role for melatonin is its relationship to circadian timing mechanisms. In addition, there has recently been assumed to be a functional connection between the pineal gland and the immune system in mammals and birds, with some findings showing melatonin to be a free radical scavenger and general antioxidant. The present study investigates the possible relationship between the circadian rhythm of melatonin and the ingestion capacity as well as superoxide anion levels of ring dove (Streptopelia risoria) heterophils. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defence mechanism. All determinations were made during 24 hr periods at 2 hr intervals. Radioimmunoassay showed an increase of melatonin serum levels during the dark period (from 20:00 to 07:00 hr) with a maximum at 04:00 hr, and a significant decline during the hours of light with a minimum at 16:00 hr. Similarly, the phagocytic index was enhanced during the night, with the maximum at approximately 04:00 hr and the minimum at approximately 18:00 hr. The same was the case in relation to phagocytic percentage. However, the superoxide anion levels were lower during darkness (minimum at 04:00 hr) and higher during the light period (maximum at 14:00 hr). In conclusion, our findings show that one pineal-mediated effect on the immune system may be a direct action of melatonin on phagocytosis and the phagocytic biochemical process, and that this neurohormone might act as an antioxidant.

Animals↗
PubMed1998

Effect of polar glycopeptidolipids from Mycobacterium chelonae (GPLp-Mc) on phagocytosis and superoxide anion production of macrophages from mice. Influence of physical activity.

It is not clear how macrophages respond to exercise when the immune system is previously activated. The aim of the present work was to determine the response of macrophages to exercise in already immunostimulated animals with polar glycopeptidolipids extracted from Mycobacterium chelonae (GPLp-Mc). Results showed an increased phagocytosis and O2- production in murine macrophages induced by the intraperitoneal administration of 25 mg/kg body weight of GPLp-Mc. In addition exercise stimulated phagocytic activity and decreased the O2- production of these cells. Unexpectedly, exercise did not potentiate the immunostimulatory effect of GPLp-Mc. However, we can conclude that the effect of exercise is not detrimental to immunostimulated animals.

Adjuvants, Immunologic↗
PubMed1998

Melatonin controls superoxide anion level: modulation of superoxide dismutase activity in ring dove heterophils.

The pineal gland and the immune system in mammals and birds are functionally connected, with some recent findings showing that melatonin, the major secretory product of the pineal gland in vertebrates, is a free-radical scavenger and general antioxidant. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defense mechanism. This in vitro study investigated the possible antioxidant action of melatonin in heterophils isolated from adult male and female ring dove (Streptopelia risoria). The superoxide anion levels (O2-.) and the superoxide dismutase (SOD) activity were evaluated as indicators of the metabolic burst of heterophils after ingestion of inert particles (latex beads) at the basal time (0 min) and 15, 30, 45, and 60 min of incubation with 100 microM melatonin. The heterophil O2-. levels, measured by the nitroblue tetrazolium reduction test, were lower after incubation in the presence of melatonin at all the times studied, a time-dependent effect. Latex beads produced a significant increase in SOD activity, whereas there was a significant decrease in the presence of melatonin. In addition, when heterophils were incubated in the presence of both latex beads and melatonin, the indole appeared to annul the enhancement of SOD activity (U-525nm) produced by latex beads. In conclusion, our findings show that the neurohormone melatonin could be a useful antioxidant.

Animals↗