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Biomedical subjects

E Ortega

Publications and source records attributed to E Ortega.

At least 109 records · Page 6Linked to original sources
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

A pilot study on the efficacy of escalating dosage of alpha-interferon for chronic hepatitis C in HIV-infected patients. The Hepatitis/HIV Spanish Study Group.

Chronic liver disease caused by hepatitis C virus (HCV) seems to present a more accelerated course in HIV-infected patients, leading to cirrhosis and liver failure in a shorter period of time than in HIV-negative individuals. As efforts to increase life expectancy in HIV-infected people progress, substantial morbidity and mortality from HCV infection is likely to arise amongst subjects infected parenterally, such as injecting drug users, haemophiliacs and transfusion recipients. Preliminary results have suggested that alpha-interferon (IFN) treatment allows higher rates of response in HIV-infected patients with higher CD4+ lymphocyte counts, suggesting a primary dependence of IFN on a preserved immune system in order to act appropriately. In an open, multicentre, prospective trial we analysed whether the use of larger doses of IFN, through an escalating schedule, might overcome the limits imposed by immune dysfunction. An interim analysis performed in 29 patients concluded that escalating the dosage did not improve the rate of response to IFN. In fact, only one (8.3%) out of 12 patients without response after 3 months of being on IFN therapy achieved response after the dosage was increased from 5 MU to 8 MU s.c. three times a week. Moreover, he relapsed 3 months after completion of treatment for 1 year.

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↗
PubMed1997

Effect of corticotropin releasing factor (CRF) injected into the median eminence on LH secretion in male rats.

We determined the dose-response relationship and examined the time-related effect of CRF (corticotropin releasing factor) injected directly into the Median Eminence (ME) on LH secretion in conscious intact and castrated male rats. Doses of 0.25, 0.75, 1, and 1.5 nmol CRF dissolved in 1 microl of saline (or saline only in the controls) were injected into the ME and blood samples collected 30, 60, 90, and 120 min postinjection to determine by RIA serum LH. CRF at doses of 0.75, 1 and 1.5 nmol significantly decreased serum LH in castrated and intact animals. The lower dose of CRF did not decrease LH in the two groups studied. The results suggest that in males as in females, CRF inhibits by itself LH secretion, at least in part, by a central action in the ME; the inhibitory effect of CRF on LH is similar in castrated and intact males; the dose of 0.25 nmoles of CRF was ineffective in decreasing LH and finally that CRF at ME levels may participate in a variety of stress-related responses, including reproduction inhibition, through LH suppression.

Animals↗
PubMed1997

Modification of natural immunity in mice by imipenem/cilastatin.

The imipenem/cilastatin constitutes a broad spectrum beta-lactam antibiotic formulation, especially used in pre and post-operatory treatments for transplanted or drug-immunosuppresed patients. The effect of the dose and the duration of the treatment with imipenem/cilastatin on some parameters of natural immunity in BALB/c mice were examined. The treatment by intraperitoneal route with 1 or 2 g/70 kg/day during 7 days did not alter significantly the parameters tested, whereas the greater dose used (4 g/70 kg/day) had an inhibitory effect on peritoneal cell counts and phagocytic activity, as well as it caused an increase on IL-1 production and natural killer activity. The greater stimulating effect of innate immunity was obtained with the lowest imipenem/cilastatin dose used (0.5 g/70 kg/day). Since this antibiotic apparently does not impair the studied innate immune responses at 1 or 2 g/70 kg/day, it seems to be especially suited for the therapy of systemic bacterial infections in immunocompromised patients.

Animals↗
PubMed1996

Role of GABAA receptors in the organization of brain and behavioural sex differences.

Sex differences in GABA neurotransmitter have been described. We have studied the involvement of the GABAA receptor in sex differences in the brain and reproductive behaviour. Neonatal administration of the GABAA agonist diazepam to male rats facilitated the induction of maternal behaviour in adults, while the antagonist picrotoxin disrupted it in females. Sex differences in the accessory olfactory bulb were also reversed, but gonadal function remained unaltered in both sexes. This suggests that neonatal changes in neuronal membrane permeability to Cl- ions may play a role in the organization of sex differences. Our study constitutes a new model for understanding the early neurobiological organization of sex differences.

Animals↗
PubMed1996

Stereoselective metabolic pathways of ketoprofen in the rat: incorporation into triacylglycerols and enantiomeric inversion.

The enantiomeric bioinversion of ketoprofen (KP) enantiomers and their incorporation into triacylglycerols were investigated in the rat (1) in vitro, using liver homogenates, subcellular fractions, and hepatocytes, and (2) in vivo, in different tissue samples after oral administration of the radiolabelled compounds. In liver homogenates or subcellular fractions, the enantiomer (S)-ketoprofen (S-KP) was recovered unchanged, whereas (R)-ketoprofen (R-KP) was partially converted into its Coenzyme A (CoA) thioester and inverted to S-KP. Both processes occurred mainly in the mitochondrial fraction. This supports the mechanism of inversion via stereoselective formation of CoA thioester of R-KP, already described for other non-steroidal anti-inflammatory drugs. Incorporation into triacylglycerols was detected after incubation with intact hepatocytes in the presence of added glycerol. The process was stereoselective for R-KP vs. S-KP (covalently bound radioactivity 26,742 +/- 4,665 dpm/10(6) cells vs. 6,644 +/- 3,179 dpm/10(6) cells, respectively). However, no incorporation was found in liver samples after oral administration of either R-KP or S-KP. On the contrary, in adipose tissue samples a significant and stereoselective formation of hybrid triacylglycerols was observed: 11,076 +/- 2,790 dpm.g-1 for R-KP vs. 660 +/- 268 dpm.g-1 for S-KP. The incorporated R/S ratio, higher in adipose tissue (R/S = 17) than in hepatocytes (R/S = 4), indicates that fat may be the main tissue store for the xenobiotic R-KP in rats.

Adipose Tissue↗
PubMed1996

Protein tyrosine phosphorylation in leukocyte activation through receptors for IgG.

Membrane receptors for the Fc portion of immunoglobulin G (IgG) antibodies (Fc(gamma)Rs) are expressed on almost every type of hematopoietic cells, where they mediate a wide variety of effector functions. A high degree of structural heterogeneity exists among Fc(gamma)Rs. The biological significance of such heterogeneity is unknown, since the structural diversity does not appear to be reflected in the binding specificity nor in the effector functions that each distinct receptor is able to mediate. Recent work has emphasized the essential role of protein tyrosine phosphorylation in the initiation of transmembrane signaling by these receptors. In this article we review the role of protein tyrosine phosphorylation in signal transduction by the different types of Fc(gamma)Rs in order to assess to what extent the structural heterogeneity of this receptor family is related to different activation pathways utilized by each of its members.

Amino Acid Sequence↗
PubMed1996

Effect of CRF injected into the median eminence on GH secretion in female rats under different steroid status.

To evaluate whether the median eminence (ME) is a site of action of CRF (corticotropin releasing factor) on GH secretion and to determine the possible role of estradiol and progesterone in modifying theses secretion, we injected CRF (0.25, 0.75, 1, and 1.5 nmol of peptide dissolved in 1 microliter of water) directly into the ME in three experimental groups of rats: Long-term ovariectomized (OVX); OVX primed by estradiol (OVX +/- E) and OVX primed by estradiol plus progesterone (OVX +/- EP). Blood was collected to determine GH (30, 60, 90, and 120 min postinjection). Serum T3, T4, and glucose levels were measured in OVX +/- E rats 30 min postinjection. CRF at all doses studied significantly decreased serum GH levels in the three experimental groups. Serum T3, T4, and glucose levels were unchanged after CRF administration. The results suggest that: CRF inhibits "per se" GH secretion, at least in part, by a central action in the ME. The inhibitory effect of CRF on GH is independent of the estrogen/progesterone status of the animal. CRF at ME levels may participate in a variety of stress-related responses, including growth inhibition, through GH suppression.

Animals↗
PubMed1996

Effect of prolactin on the in vitro phagocytic capacity of macrophages.

Prolactin (PRL) plays a modulatory role in immune function. Previous studies have demonstrated that physical activity (swimming until exhaustion) provokes a stimulation in the phagocytic function of peritoneal macrophages. In this study, we have investigated the possible role of PRL as a mediator of physical activity-induced stimulation of macrophage phagocytosis. Peritoneal macrophages from BALB/c mice were incubated for 30 min with 1.1 (basal concentration in these animals), 2.2 (the concentration observed in plasma after swimming until exhaustion) and 8, 16 and 22,000 ng/ml of PRL. The results indicated that incubation of peritoneal macrophages with a concentration of PRL similar to that observed in plasma immediately after physical activity stress stimulates phagocytic capacity. This stimulation was also observed after incubation of macrophages with the higher concentrations of PRL. We conclude that PRL may be considered as a mediator of physical activity-induced stimulation of macrophage phagocytosis, confirming the immunoregulatory role of this hormone.

Animals↗
PubMed1996

Effect of beta-endorphin on adherence, chemotaxis and phagocytosis of Candida Albicans by peritoneal macrophages.

There is growing evidence about the role of neuroendocrine hormones in the regulation of the immune system. In the present study we have examined effects on different stages of phagocytic function of peritoneal macrophages from BALB/c mice induced by beta-endorphin. Peritoneal macrophages were incubated (30 min at 37 degrees C) in vitro with 0.22, 0.5 or 2200 ng/ml of this hormone. Adherence capacity was evaluated by means of a substrate adherence technique, chemotaxis in Boyden chambers, and ingestion of Candida albicans on migration inhibitory factor (MIF) dishes. No changes in adherence capacity were found. Chemotaxis, however, increased, and concentration of beta-endorphin correlated directly with stimulation. Incubation of macrophages with 0.5 ng/ml of beta-endorphin also stimulated phagocytosis of Candida albicans. These results indicate that beta-endorphin acts on peritoneal marine macrophages, stimulating some stages of their phagocytic function.

Animals↗
PubMed1996

Corticosterone, prolactin and thyroid hormones as hormonal mediators of the stimulated phagocytic capacity of peritoneal macrophages after high-intensity exercise.

The aim of this study was to evaluate the effect of high-intensity physical activity (swimming until exhaustion) with or without previous training on the phagocytosis and destruction of inert particle capacities of macrophages, and the role of corticosterone, prolactin and thyroid hormones as possible hormonal mediators. The results indicated that high-intensity exercise provokes a stimulation of both phagocytosis and destruction of inert particles when performed in absence of previous training. However, swimming until exhaustion after a one month training program (25 min/day) induced an increase in phagocytosis but not in the destruction of latex beads. Corticosterone, prolactin and thyroid hormones can be considered as hormonal mediators of the exercise-induced stimulation of phagocytosis, since these hormones increased plasma concentration, and the in vitro incubation of macrophages with the same higher physiological plasma concentrations of each hormone, as after exercise, also induced phagocytic stimulation of these cells.

Animals↗
PubMed1996

Inhibition of 5'DI and 5'DII L-tiroxine (T4) monodeiodinases. Effect on the hypothalamo-pituitary ovarian axis in adult hypothyroid rats treated with T4.

Hypothyroid female rats were treated with T4 and their 5'DI and 5'DII deiodinases were inhibited by PTU and IOP administration to determine whether the effect of T3 on reproductive function is a primary event at hypothalamo-pituitary levels or ovarian levels. Hypothyroid adult female rats were divided into four groups: Hypothyroid without treatment (H); hypothyroid treated with T4 (H-T4); hypothyroid treated with T4 plus propylthiouracil (H-T4-PTU), and hypothyroid treated with T4 plus iopanoic acid (H-T4-IOP). A group of euthyroid rats (E) was included as control. Estrous cycle, ovarian histological changes and serum estradiol and gonadotropin levels (basal and after GnRH) were searched in all groups. In view of our results and since sexual cycles and puberal pattern in gonadotropin secretion were restored after all treatments we can suggest: That T4 could have an intrinsic effect on reproductive function in adult hypothyroid female rats or that another compensatory T3 mechanism unaffected by IOP could exist. The present report points out that the effect of T3 on reproductive function could be a primary event at hypothalamopituitary levels although an effect at ovarian levels could not be excluded.

Animals↗
PubMed1996

Exercise-induced stimulation of murine macrophage phagocytosis may be mediated by thyroxine.

The present study was designed to test the hypothesis that changes in plasma concentrations of hormones may be responsible for the exercise-induced macrophage phagocytic stimulation. The effect of 30-min incubation of macrophages with plasma from mice previously exposed to swimming until exhaustion (with or without previous training) was studied, and the results showed a similar stimulation of the phagocytic capacity (attachment and ingestion) of these cells to that found in previous studies after exercise. Also, changes in plasma concentration of both thyroxine (T4) and 3,3',5-triiodo-L-thyronine (T3) after exercise were measured, and their effect on phagocytic capacity after in vitro incubation with peritoneal macrophages was investigated. Results indicated that, after exercise, plasma concentrations of T3 and T4 increased. Incubation of peritoneal macrophages for 30 min with a concentration of T3 similar to that observed in the plasma immediately after exercise (1.5 ng/ml) induced no modifications in the phagocytic capacity. However, a physiological concentration of T4 after exercise (75 ng/ml) stimulated the phagocytic capacity of peritoneal macrophages. In addition, a 10,000-fold greater concentration of these thyroid hormones did not modify the macrophage function. It is concluded that physiological concentration of T4 may be a mediator of the stimulation of the phagocytic function in macrophages induced by exercise.

Animals↗
PubMed1996

[Kaposi's sarcoma of the bile ducts with cutaneous involvement in a patient with AIDS].

A 30 year-old man with acquired immunodeficiency syndrome was admitted because of abdominal pain, jaundice and fever. A severe pancreatitis without gallstones was detected. Later, dilation of biliary tract and clinical worsening appeared. Cholangiography revealed sclerosing cholangitis and papillary stenosis. Kaposi's sarcoma of the gallbladder invading the biliary tract was found. Only two reports of Kaposi's sarcoma of the biliary tract without cutaneous lesions have been published in a living patient. Pancreatitis has not been previously described as a clinical presentation of this malignancy.

Acquired Immunodeficiency Syndrome↗
PubMed1995

A study of the role of corticosterone as a mediator in exercise-induced stimulation of murine macrophage phagocytosis.

1. It is generally accepted that physical activity provokes changes in the immune system. Previous studies have demonstrated that the stress of physical activity (swimming until exhaustion) increases the phagocytic activity of peritoneal macrophages. However, the precise mechanisms remain unknown. 2. Two experiments were performed in the present study. (A) Peritoneal macrophages from control mice were incubated with plasma from three different groups of mice: (1) mice subjected to swimming until exhaustion with no previous training, (2) mice subjected to the same activity but with 1 month of training (30 min day-1), and (3) a control (non-exercised) group. The differences in the resulting phagocytic (attachment and ingestion) capacity were measured. (B) Changes in the concentration of plasma corticosterone after exercise were also measured, and the effect of incubation with the postexercise plasma corticosterone level on the phagocytic activity of peritoneal macrophages was then studied in vitro. 3. The results were: (A) incubation with plasma from both groups of exercised mice (with and without previous training) led to increased levels of phagocytic capacity (number of C. albicans cells ingested per 100 macrophages). (B) Incubation with a corticosterone concentration of 0.72 mumol l-1 (similar to that observed in plasma immediately after exercise) raised the phagocytic capacity (144 +/- 12 after incubation with 0.72 mumol l-1 vs. 93 +/- 19 after incubation with 0.24 mumol l-1). This increase was also significantly greater than that observed with 7.2 mumol l-1 corticosterone. 4. It is concluded that corticosterone may mediate the increased phagocytic function of peritoneal macrophages induced by exercise.

Animals↗