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Biomedical subjects

M Rubio

Publications and source records attributed to M Rubio.

At least 145 records · Page 8Linked to original sources
PubMed1994

Ependyma: phylogenetic evolution of glial fibrillary acidic protein (GFAP) and vimentin expression in vertebrate spinal cord.

The phylogenetic evolution was studied of both glial fibrillary acidic protein (GFAP) and vimentin expression in the ependyma of the adult vertebrate spinal cord. Eleven species from different vertebrate groups were examined using different fixatives and fixation procedures to demonstrate any differences in immunoreactivity. GFAP expression in the ependymal cells showed a clear inverse relation with phylogenetic evolution because it was more elevated in lower than in higher vertebrates. GFAP positive cells can be ependymocytes and tanycytes, although depending on their structural characteristics and distribution, the scarce GFAP positive ependymal cells in higher vertebrates may be tanycytes. Ependymal vimentin expression showed a species-dependent pattern instead of a phylogenetic pattern of expression. Vimentin positive ependymal cells were only found in fish and rats; in fish, they were tanycytes and were quite scarce, with only one or two cells per section being immunostained. However, in the rat spinal cord, all the ependymocytes showed positive immunostaining for vimentin. The importance of the immunohistochemical procedure, the cellular nature of GFAP positive ependymal cells and the relationship between tanycytes and ependymocytes are discussed, as well as GFAP and vimentin expression.

Animals↗
PubMed1994

In vitro and in vivo evidence for direct dopaminergic inhibition of VIP-immunoreactive pituitary cells.

In order to establish whether dopamine is involved in the regulation of immunocytochemical expression of VIP in pituitary cells, in vivo and in vitro studies were carried out on male rats after treatment with haloperidol and dopamine, respectively. In the in vivo studies, following intraventricular (third ventricle) administration of haloperidol, an increase in the total number of VIP-immunoreactive cells (p < 0.05) was observed; additionally, the cellular, cytoplasmic and nuclear areas were increased (p < 0.01). The in vitro studies demonstrated that dopamine induces a significant decrease (p < 0.05) in the total number of VIP-immunoreactive cells, which were smaller than the cells from the control dishes, because dopamine induces a significant decrease in their cellular, cytoplasmic and nuclear areas (p < 0.01). These results support the hypothesis that dopamine is a physiological inhibitor of pituitary VIP expression and suggest that dopamine modulates the auto- or paracrine effects of VIP in the rat pituitary.

Animals↗
PubMed1994

Predominance of gram-positive microorganisms as a cause of septicemia in patients with hematological malignancies.

OBJECTIVE: To ascertain the etiology and outcome of episodes of bacteremia and fungemia over a three-year period (1990-1992) in patients with hematological malignancies. DESIGN: Retrospective study. SETTING: Hematology service of a 1,500-bed Spanish university hospital. RESULTS: Of a total of 178 episodes of significant bacteremia or fungemia in 101 patients, 53% affected patients with acute leukemia. Gram-positive microorganisms were found to be the cause in 70% of the monomicrobial episodes. The most frequently isolated microorganism was coagulase-negative Staphylococcus (35%), followed by Staphylococcus aureus (11%). Most blood-stream infections occurred during an episode of neutropenia (59%). A total of 34 patients died during hospitalization; in 14, infection was the cause of death. CONCLUSIONS: A marked increase in the incidence of bacteremias caused by gram-positive microorganisms has been observed in our hospital over the last 10 years, especially in patients with hematological malignancies. The mortality due to bacteremia is similar to that found by other authors in series of bacteremia in hematological patients, and we have not found significant differences in the mortality due to bacteremia between neutropenic and non-neutropenic patients (Infect Control Hosp Epidemiol 1994;15:101-104).

Adolescent↗
PubMed1994

Liver oxygen uptake dependence and mitochondrial function in septic rats.

Defective oxygen consumption and a pathological dependence of oxygen uptake on O2 supply have been considered important events in sepsis. To relate these features with tissue and mitochondrial metabolism, we studied oxygen uptake in whole isolated and perfused rat liver at two O2 supply levels, in the same liver slices, and in isolated liver mitochondria. Experimental sepsis in rats was induced by cecal ligation and double-gauge puncture. The results showed that liver and tissue slices from septic animals had a 60% greater O2 uptake than that of controls and that, during sepsis, liver O2 uptake was markedly dependent on O2 supply. Concomitantly, mitochondrial O2 uptake was nearly 30% greater with malate-glutamate as substrate, but not with succinate; lowering O2 concentration in the medium did not alter the enhanced function. In submitochondrial, only NADH-dehydrogenase activity was 100% higher in septic samples. At least, in some tissues, O2 dependence is a function of O2 availability, sensitized by increased mitochondrial O2 uptake related to changes in respiratory enzymes.

Adenosine Diphosphate↗
PubMed1994

Changes in the neurosecretory axons of the neural lobe of the hypophysis of rats treated with met-enkephalin. An ultrastructural study.

Following administration of met-enkephalin into the third ventricle of rats of both sexes, an ultrastructural-morphometric study was carried out of the neural lobe of the hypophysis, comparing the results with those obtained in untreated animals, controls (injected intraventricularly with distilled water) and animals previously receiving naloxone intraperitoneally. In the untreated and control animals, both males and females, there was a high percentage (about 70%) of neurosecretory axons considered to have a normal morphology; after met-enkephalin administration, this percentage decreased and was accompanied by a rise (slightly more pronounced in the females) in the percentage of degranulated axons and a slight rise in axons with a morphology indicative of regenerative and degenerative phases. Previous administration of the opiate antagonist naloxone led to a rise in the number of axons in the degenerative phase with respect to the other groups of animals; this occurred in both sexes.

Animals↗
PubMed1994

Immunohistochemical-morphometric study of the LH-adenohypophyseal cells following chronic treatment with met-enkephalin.

In order to test the possible effect of chronic treatment with met-enkephalin upon the LH-adenohypophyseal cells, an immunohistochemical-morphometric study was carried out in rats of both sexes receiving a daily dose of 40 micrograms of met-enkephalin intramuscularly over 15 days. Following the administration of the opioid, a drastic decrease in the cellular, cytoplasmic and nuclear areas when compared to the normal and control animals was detected. Morphologically, the main finding in males was the appearance of irregularly-shaped pseudovacuolated cells. On the other hand, in females a decrease in the intensity of reaction was found. These results strongly suggest a decrease in the activity of the LH-adenohypophyseal cells following chronic administration of met-enkephalin.

Animals↗
PubMed1993

Astroglial pattern in the spinal cord of the adult barbel (Barbus comiza).

The distribution and the structural, ultrastructural and immunohistochemical characteristics of the astroglial cells in the spinal cord of the adult barbel (Barbus comiza) have been studied by means of metallic impregnations (Golgi and gold-sublimate), immunohistochemical (GFAP and vimentin) and electron microscopic techniques. GFAP-positive cells were mainly distributed in the ependyma and in the periependymal region, but they have also been observed at subpial level in the anterior column. The ependymocytes were heterogeneous cells because they showed different immunohistochemical characteristics: GFAP-positive, vimentin-positive or non-immunoreactive cells. The radial astrocytes showed only GFAP immunoreactivity, and their processes ended at the subpial zone forming a continuous subpial glia limitans. Desmosomes and gap junctions between somata and processes of radial astrocytes were numerous, and a relationship between radial astroglial processes and the nodes of Ranvier was also described. The perivascular glia limitans was poorly developed and it was not complete in the blood vessels of the periependymal zone; in this case, the basal lamina was highly developed. An important characteristic in the barbel spinal cord was the existence of a zone with an abundant extracellular space near the ependyma. The presence of radial astroglial somata at subpial level, the existence of vimentin-positive ependymocytes and the abundant extracellular space in the periependymal zone is discussed in relation to the regeneration capacity and the continuous growth showed by fish. Moreover, the abundance of gliofilaments and desmosomes leads us to suggest that mechanical support might be an important function for the astroglial cells in the barbel spinal cord.

Animals↗
PubMed1993

High ammonia diet: its effect on the glial fibrillary acidic protein (GFAP).

The effect of a recent hyperammonemic model, consisting of a high ammonia diet for 3, 7, 15, 45, and 90 days, on glial fibrillary acidic protein (GFAP) in the rat spinal cord and on blood ammonia levels has been studied. The high ammonia diet was prepared by mixing a standard diet with ammonium acetate (20% wt/wt); in addition, 5 mM of ammonium acetate was added to the water supply. GFAP contents were determined by means of immunoblotting analysis. The results demonstrated that this high ammonia diet model neither induces significant changes in GFAP immunoreactivity, nor modifies total protein concentration, and only induces significant blood hyperammonemic levels in the first days of treatment. An adaptive response to the diet is suggested and discussed to explain these results. A relation between ammonia and GFAP expression is suggested because transient hyperammonemia induces transient, although no significant, changes on GFAP expression.

Ammonia↗
PubMed1993

Effects of experimentally induced hyperammonemia on glial fibrillary acidic protein (GFAP) in the rhombencephalon of goldfish (Carassius auratus L.).

This experimental study was made to know the effect of hyperammonemia on glial fibrillary acidic protein (GFAP) in the glial cells of posterior rhombencephalon in the goldfish (Carassius auratus L.). Hyperammonemia was induced by elevating the ammonia concentration in the tank water to 0.88 mM with ammonium chloride; the ammonia level in the control tank water was < 0.1 mM. The GFAP levels were measured at 8, 16, 30, 60, 90 and 120 days. GFAP was quantified with a digital analysis system and a transient heterogeneous decrease of GFAP was observed. Hyperammonemia mostly affected GFAP in the astrocyte processes associated with cholinergic pathways. An explanation for the adaptive response to hyperammonemia by fish astrocytes is suggested.

Ammonia↗
PubMed1993

Calretinin immunoreactivity in the magnocellular neurosecretory nuclei of the rat hypothalamus.

The distribution of calretinin-immunoreactivity in the magnocellular neurosecretory nuclei of the rat hypothalamus was studied using a polyclonal antibody and the avidin-biotin immunoperoxidase technique. Calretinin-immunoreactive neurons were observed in the supraoptic and paraventricular nuclei. Additionally, we detected for the first time, immunoreactive neurons located in the circularis and fornicals nuclei, and isolated positive neurons situated in the hypothalamic area located between the supraoptic and paracentricular nuclei. When these results were compared to those obtained in previous studies for another two calcium-binding proteins: calbindin D-28k and parvalbumin, two major differences may be concluded: a) a different distribution of calretinin, especially in the paraventricular nucleus, and b) an expression of calretinin lower than calbindin D-28k and higher than parvalbumin in the magnocellular hypothalamic nuclei. Of special interest is the fact that calretinin is one of the few markers which demonstrates predominantly parvicellular neurons in the paraventricular nucleus. Although the exact biochemical function of these three calcium-binding proteins remains unknown, their uneven and characteristic distributions strongly suggest that specific neuronal populations in the hypothalamus may use alternatively different calcium-sequestering molecules.

Animals↗
PubMed1993

Morphometric analysis of the hypoactivity of FSH-immunoreactive cells in estrogen-primed male rats.

In order to evaluate the repercussions of estradiol treatment on the morphology and activity of FSH-producing cells, an immunocytochemical and morphometric study was carried out in male rats treated chronically with estradiol, relating those findings to serum FSH levels at the time of sacrifice. Chronic administration of estradiol led to a decrease (p < 0.01) in serum hormone levels that was accompanied by a marked decrease in cellular size (p < 0.01) due to a decrease in nuclear and cytoplasmic area. Our findings suggest for the adult male rat an inhibitory effect on the synthesis and release of FSH following testicular atrophy induced by treatment with estradiol.

Analysis of Variance↗
PubMed1993

[Pharmacokinetics of ceftazidime in newborn infants].

A pharmacokinetic study of ceftazidime was performed in newborn children. Six premature infants with a body weight up to 2000 g and with symptoms of pneumonia (Table 1) were treated with ceftazidime (50 mg/kg body weight) by endovenous route. Plasma concentrations of the antibiotic (Fig. 1) were determined by HPLC. A kinetic behavior was described through a compartment model independent analysis. The calculated parameters were as follows: half-life (T1/2z = 4.05 +/- 0.81 h) apparent volume of distribution (Vz = 686.0 +/- 258.6 ml/kg), elimination rate constant (lambda z = 0.18 +/- 0.04h-1), area under curve (AUC = 464.4 +/- 139.1 mu gh/ml, mean residence time (MRT = 5.2 +/- 1.3 h), and total clearance (CI = 114.9 +/- 30.0 ml/h. kg) (Table 2). Good correlation was observed (r = 0.83, p < 0.05 between lambda z = and Vz). The loading and maintenance doses calculated for enterobacteria and P. aeruginosa were 15 and 13 mg/kg i.v. respectively each 12 h.

Ceftazidime↗
PubMed1993

[Epidemiologic and clinical characteristics and clinical course of the HIV positive patient infected by heterosexual transmission].

We reviewed the features of patients with human immunodeficiency virus (HIV) infection, whose only way of acquisition was heterosexual contacts, analyzing differences with others risk groups. Epidemiological features (age, gender, family situation, socioeconomic status and sexual behavior), clinical manifestations immunological status, and evolution of 40 patients with HIV infection through heterosexual contact are studied, and compared with others risk groups. All were attended in our center from 1985 to October 1991; 15 were in stage IV. Along the study period, the proportion of heterosexual patients has steadily increased to represent 40% on total number of acquired immunodeficiency syndrome (AIDS) cases diagnosed in 1991. This study allow to establish two groups of patients depending on the gender. All men had had occasional sexual contacts with prostitutes, most had no stable partner, they mainly were between their fourth and sixth decade of life, and they were stable partners of seropositive patients or prostitutes, they had an averaged age significantly lower than men, and they were diagnosed in earlier stages. Two groups with different features can be established among the patients infected through heterosexual contacts. Men are adults, and acquired HIV infection through contacts with prostitute; they are diagnosed in late phases of the disease. On the contrary, women are younger, with no homogeneous patterns of behavior and they are diagnosed in earlier stages. Complications throughout the evaluation were similar in the heterosexual and in the other groups.

Adult↗
PubMed1993

Creation of a Spanish nephrological nursing accrediting course.

In 1989, the Spanish Association of Nephrological Nursing (Sociedad Espanola de Enfermeria Nefrologica--SEDEN) created a course directed to all graduates in nephrological nursing in Spain to answer a need for further training. This article details the objectives, methodology, and results of the Course for Accrediting Specialized Knowledge in Nephrological Nursing since it was created.

Education, Nursing, Continuing↗
PubMed1993

Ultrastructural and morphometric changes in somatotropic cells following intraventricular administration of Met-enkephalin to rats.

An ultrastructural and morphometric study of Kurosumi et al. (1986) on type 1 GH cells in adult Sprague-Dawley rats, after the intraventricular administration of Met-enkephalin, with or without prior intraperitoneal administration of naloxone, was carried out and then compared to the same cellular type of untreated animals and of animals intraventricularly treated with distilled water, used as controls. The study demonstrated an increase of cellular (p < 0.05) and nuclear (p < 0.05) areas, an enlargement and dilation of the cisternae of the Golgi complex, with an increase in the Golgi area (p < 0.01) and the immature granules (p < 0.01); a greater development of the rough endoplasmic reticulum and an increase in the number of exocytosis (p < 0.01) and, only in male rats, an increase in the mature secretory granules (p < 0.01). The prior administration of naloxone prevented the appearance of these changes and also produced an increase (p < 0.01) of the organelles involved in the crinophagic phenomenon. These results suggest that the opioids play a modulating role, stimulating the synthesis and secretion of GH, which affects the ultrastructural features of the hypophyseal GH cells.

Animals↗