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Biomedical subjects

A B Rodríguez

Publications and source records attributed to A B Rodríguez.

At least 19 recordsLinked to original sources
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↗
PubMed1997

Effect of serum from breast- or formula-fed infants on polymorphonuclear leukocyte function.

The aim of the present study was to determine the influence of serum from formula and breast-fed infants on neutrophil function (as measured by the attachment and phagocytosis of Candida albicans) as well as the chemoattractant activity of the serum. The results indicate that: (a) serum from breast-fed infants induces a greater chemoattractant activity in neutrophils than serum from 3-month-old formula-fed infants; (b) the highest values of the attachment capacity were obtained after incubation of neutrophils with serum from 1-month-old breast-fed infants; and (c) serum from breast-fed infants induces a greater phagocytic capacity against C. albicans in neutrophils than serum from formula-fed infants.

Adult↗
PubMed1997

Melatonin and the phagocytic process of heterophils from the ring dove (Streptopelia risoria).

A functional connection between the pineal gland and the immune system in mammals and birds has been established. This study investigates the effect of melatonin upon the non-specific immunity of heterophils isolated from the ring dove. The different stages of the phagocytic process: adherence to nylon fiber, spontaneous and induced mobility, ingestion of latex beads and digestion were evaluated for heterophils incubated in the presence of 5, 25, 50, 75, or 100 microM of melatonin. In addition, the chemoattractant power of the hormone for heterophils was studied. The 100 microM melatonin dose possessed a significant chemoattractant ability for heterophils whilst ingestion of latex particles was enhanced at all doses studied. The superoxide anion level, as measured by the free radicals produced during the metabolic burst, is decreased after incubation with 100 microM of melatonin.

Animals↗
PubMed1996

In vivo effect of teicoplanin and vancomycin upon haemolytic and bactericidal activity of serum against Staphylococcus aureus.

The present study was undertaken to determine whether teicoplanin and vancomycin influence the hemolytic and bactericidal activity of serum obtained from mice (Swiss, aged 15 +/- 2 weeks). Haemolytic activity was measured in CH-50 units (which represents the capacity of serum complement to lyse 50% of sheep red blood cells in the presence of specific antibody) and the bactericidal activity was estimated from the number of colony-forming units (CFU/ml) of Staphylococcus aureus that survived after 24 h of incubation in the presence of serum. The results indicate that (1) teicoplanin and vancomycin increase the haemolytic activity of serum; (2) in the serum from animals treated with both teicoplanin or vancomycin, the number of CFU/ml of Staphylococcus aureus declines; and (3) these antibiotics appear to have a similar effect upon the complement system.

Animals↗
PubMed1996

Comparative study of the effect of teicoplanin and vancomycin upon the phagocytic process of peritoneal macrophages.

The effect of Teicoplanin and Vancomycin upon the phagocytic process was compared by evaluating the different activities of the peritoneal macrophage phagocytic function from mice treated with these antibiotics. The results indicated that teicoplanin and vancomycin increased both the substrate adherence and chemotaxis of peritoneal macrophages and that neither antibiotic, at the concentrations of 10, 25, 50, 75 and 100 mg/l, had any chemoattractant capacity for peritoneal macrophages. There was an increase in the attachment of Candida albicans only in the macrophages from mice treated with vancomycin. The phagocytosis of C. albicans, Staphylococcus aureus, Escherichia coli and inert particles as well, as the nitroblue tetrazolium reduction capacity (microbicide capacity) increased in the presence of both antibiotics. The C. albicans digestion capacity increased only in the peritoneal macrophages from mice treated with teicoplanin.

Animals↗
PubMed1994

Decline in the phagocytic function of alveolar macrophages from mice exposed to cigarette smoke.

An investigation was made of the effects of a short and acute exposure to cigarette smoke on the capacity of alveolar macrophages from mice to carry out all stages of the phagocytic process. Cigarettes were commercial 80 mm filter cigarettes that contained 17 mg of tar and 1.1 mg of nicotine per cigarette. The acute exposure of each animal was with one cigarette for 15 min (until the complete consumption of the cigarette) in a box-shaped plastic chamber, 7732 cm3 vol and 450 cm2 floor surface, with a 3 cm dia airhole. Animals were sacrificed immediately after the exposure to the smoke. The results showed no differences either in the adherence or in the chemotaxis capacities between alveolar macrophages from control mice and from mice exposed to cigarette smoke. However, there was a significant decline both in attachment capacity and in ingestion capacity for Candida albicans. The reason for this was a decline in the number of macrophages with phagocytic capacity (percent of phagocytosis) and in the number of C. albicans phagocytized per cell (phagocytic efficiency). The conclusion is that a short, acute exposure to a smoke-filled atmosphere induced a decrease in the phagocytic function of alveolar macrophages.

Animals↗
PubMed1994

Effect of pinealectomy upon the nonspecific immune response of the ring-dove (Streptopelia risoria).

The different stages of the phagocytic process by granulocytes of pinealectomized or sham-pinealectomized ring doves (Streptopelia risoria) as well as hematological parameters (total white blood cells, smear, and total protein) and serum hormone levels (triiodothyronine (T3), thyroxine (T4), and corticosterone) were studied. A number of immunological parameters of the phagocytosis process, including adherence capacity, mobility rate, the phagocytosis capacity for inert particles and the digestion capacity of ingested material, were studied. Adult male ring doves were injected intravenously with either 0.1 ml of normal sheep serum (NSS) or saline (SS). Blood samples were collected before injection, and 1 hr, 3 hr, 24 hr, and 4 days afterwards. The results indicate that pinealectomy produces a significant increase in the number of total white blood cells and total protein concentration in plasma in addition to altering different stages of the phagocytic process. During the immunization study, a decrease in the percentage of leukocytes and lymphocytes and an increase in the percentage of heterophils accompanied by an increase in the concentration of serum corticosterone were observed 3 hr following treatment. For the immunological parameters, adherence capacity and latex bead ingestion were increased 3 hr after NSS injection and the NBT reduction test 3 and 24 hr after NSS treatment. In addition, the administration of NSS produced a significant increase in serum T3 and T4 concentrations 4 days following injection. These results show that pinealectomy has a marked effect on both the number and function of immune cells.

Animals↗
PubMed1994

Effect of cefepime (BMY-28142) on the hemolytic and bactericidal activity of serum in vivo and in vitro.

The present study was undertaken to determine whether cefepime (BMY-28142) could influence the hemolytic and bactericidal activity of serum both in vivo and in vitro. For the in vivo studies, mice (Swiss aged 15 +/- 2 weeks) were studied before and 1, 2, 4, 8, and 12 h after an intramuscular injection of 200 mg/kg of cefepime. Likewise, another group of mice were injected for 7 days with a daily injection of the same dose as before, and sacrificed one hour after the last injection. For the in vitro studies, samples were incubated in the presence and absence of cefepime (1/2, 1/4 and 1/8 MIC against Staphylococcus aureus) (2.5, 1.25 and 0.625 mg/l respectively). The results indicate that cefepime at sublethal concentrations increases the bactericidal activity of serum both in vivo and in vitro against S. aureus, but does not significantly modify the hemolytic activity of the complement.

Animals↗
PubMed1993

Stimulation of phagocytosis against Staphylococcus aureus by teicoplanin and vancomycin.

The constructive interference of teicoplanin with phagocytosis of Staphylococcus aureus by murine macrophages and human neutrophils, studied in vivo and in vitro respectively, was compared with that of vancomycin. Both teicoplanin and vancomycin increased the phagocytosis by macrophages. All the concentrations of teicoplanin increased the phagocytosis by neutrophils, but only the highest concentrations of vancomycin (50 mg/l and 100 mg/l) had this effect, greater values being found with teicoplanin in all cases.

Animals↗
PubMed1993

[Uptake and intraphagocytic activity of teicoplanin in human neutrophils].

The incorporation of antibiotics in phagocytes is necessary for their activity against intracellular microorganisms. The ability of Teicoplanin to enter in human polymorphonuclear leukocytes (PMNs) after infection with Candida albicans was investigated using an in vitro model previously described. Human PMNs were preincubated with Candida albicans for 30 min, after which antibiotic (100 mg/l) was added to cell suspension during 1, 5, 15, 30 and 60 min. The results were expressed as the ratio of the cellular concentration of antibiotic to the extracellular concentration (C/E). Teicoplanin bound rapidly to phagocytes (with a C/E = 2.12 after 1 min of incubation), being the cell-associated drug approximately similar during the entire incubation period. At the same time, Teicoplanin increases the percentage of mortality of Candida albicans previously ingested, which was dependent of the incubation period in its presence.

Adult↗