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Biomedical subjects

J F Escanero

Publications and source records attributed to J F Escanero.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effects of physical training during the growth on the granulation of myo-epithelioid cells of the rat kidney.

The behaviour of the granulation of the myo-epithelioid cells of the juxtaglomerular apparatus of the kidney and its relationship with the plasma concentrations of renin, sodium and potassium, and plasma osmolality have been studied in male and female Wistar rats that have been subjected to a programme of moderate physical exercise throughout their period of growth. In the trained rats a significant increase in the juxtaglomerular granulation index and a significant decrease in plasma renin concentration has been observed, the changes being more prominent in the female animals. Moreover in the trained rats significant increases in plasma sodium, potassium and osmolality have been observed.

Aging↗
PubMed1991

Effects of glucagon on serum calcium, magnesium and strontium levels in rats.

The pharmacological effects of glucagon (0.05 mg/kg b.wt. day) on serum calcium, magnesium and strontium levels were analyzed in order to clarify the response of divalent cations to glucagon administration and its possible relation with calcitonin release stimulation. The results show significant decreases in serum calcium and strontium levels 2 h after glucagon administration, and in daily administration the effect peaks on the 3rd day and returns to baseline values by the 9th day. In contrast, the serum magnesium increases significantly by the 3rd day of daily glucagon administration and continues to increase until the 9th day. Calcitonin administration (90 mU Medical Research Council unit)/100 g b.wt.) significantly reduces the serum calcium, strontium and magnesium levels up to the 3rd day of treatment, just when the glucagon effect is highest. Other additional mechanisms may be involved besides the calcitonin release stimulation, in the response induced in divalent cations--particularly magnesium--by the exogenous administration of glucagon.

Animals↗
PubMed1991

Influence of lithium and exercise on serum levels of copper and zinc in rats.

The variations in serum levels of Cu and Zn induced by exercise in rats undergoing Li therapy are determined. The results show that exercise until exhaustion leads to a reduction in the Li concentration, which is more pronounced in rats subjected to training (to 50% maximum capacity) in the week before the test. The serum levels of Zn and Cu increased significantly with exhaustion in untrained rats, while there were no significant alterations in trained rats, except for serum Zn in those not treated with Li. The modifications in serum induced by exhaustion are lower in rats treated with Li. It is likely that Li and exercise have opposite effects on the tissue distribution of the two ions studied.

Animals↗
PubMed1990

Effect of swimming to exhaustion, at low temperatures, on serum Zn, Cu, Mg and Ca in rats.

In order to study the response of plasma trace minerals during exercise in cold water at varying temperatures, three groups of ten male Wistar rats each were forced to swim until exhaustion in water at different constant temperatures (10, 20 and 32 degrees C), while another 3 groups were kept at rest in water at the same temperatures and another group at rest out of the water, at room temperature (21 degrees C). Rectal temperature (RT) was measured before and after the exercise. Samples of arterial blood were obtained under anaesthesia (pentobarbital) from the abdominal aorta after the exercise, and serum concentrations of Cu, Zn, Mg and Ca were determined by flame atomic absorption spectrophotometry (FAAS). The swimming time (ST) decreased in cold water, the values obtained at 10 and 20 degrees C being 3.3% and 8.5%, respectively, of those observed at 32 degrees C. The RT of the animals swimming at 32 degrees C was 32.5 +/- 1.8 degrees C (mean +/- SD) and fell to 25.0 +/- 2.0 and to 19.1 +/- 1.5 degrees C in those swimming, respectively, at 20 and 10 degrees C. The concentrations of Mg, Cu and Ca were significantly higher (+50%, +36% and +7%, respectively) in animals subjected to exercise with respect to the control groups in water, although there were no differences among the three groups. On the contrary, Zn rose progressively with the increase of WT (+32% at 10 degrees C, +60% at 20 degrees C and +76% at 32 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Changes of plasma zinc and copper at various times of swimming until exhaustion, in the rat.

To characterise the response in the plasma concentration of Zn a total of 60 male Wistar rats (250 g) were divided into six groups of ten rats each. One group did not exercise; the five other groups swam at constant temperature (32/34 degrees C) and were respectively studied after 30, 60, 90, 120 min and at exhaustion. After anesthesia, rectal temperature (RT) was measured and arterial blood was obtained from the abdominal aorta. Acidbase balance, arterial blood gases and plasma concentration of Zn, Cu, Mg, Ca and Hb were measured. The swimming time at exhaustion was (mean +/- SD) 284 +/- 66 min. RT only changed after exhaustion. (H+) increased significantly at 30 min then did not change until exhaustion. (Hb) increased slightly at 90 and 120 min of swimming and after exhaustion. No changes of Mg and Ca except at exhaustion were observed (+7 and +50% respectively). On the other hand, Cu (30 min = +16%; 60 min = +29% exhaustion = +36%) and Zn (30 min = +26%; 60 min = +39%; 120 min = +66% and exhaustion = +76%) increased significantly through the two first hours of exercise. Haemoconcentration, acidosis and RT did not explain the progressive increase of Zn, which seems to be time-dependent and probably related to some degree of stress.

Acid-Base Equilibrium↗
PubMed1990

[The effect of thyroparathyroidectomy, parathyroid hormone and calcitonin on plasma strontium in rats].

The effect of thyroparathyroidectomy (TPTX) on the plasmatic Sr concentrations in rats previously supplemented with this element, has been studied, as well as its effect on the treatment of TPTX rats with hormonal combinations and, finally, the one presenting hormonal excess or defect of the phosphocalcium metabolism regulating hormones: parathormone (PTH) and calcitonin (CT). Twenty four hours after TPTX, the plasmatic Sr concentrations show a pattern similar to those of Ca and Mg and contrary to Pi. The subsequent evolution is different, as the plasmatic concentrations increase, probably due to the maintenance of Sr supplementation. The administration of this element to TPTX rats and the treatment with a hormonal combination with two of the following hormones: PTH, CT and T4 antagonize the hormonal effect on the restoration of the plasmatic concentrations of the elements analyzed. The PTH excess and defect (TPTX treated with CT + T4) show plasmatic increases in Sr; the CT excess provokes decreases while the defect (administration of PTH + T4) causes increases. The T4 administration reproduces the CT effects, but inconsistently. These results suggest that CT may be the hormone that plays a regulating role in the plasmatic Sr concentrations.

Animals↗
PubMed1990

[Evolution of the number of authors in clinical and basic science journals in the Spanish language].

The number of signing authors in Revista Clínica Española. Revista Española de Fisiología and Revista Española de Oncología have been analyzed from their first to the last received issue. The results obtained show an increasing number of authors in all journals specially during the 70s. The results also point out a relative decrease in the number of authors in basic sciences in relation to clinical publications. The increase in the number of authors in The Revista Española de Oncología has started somewhat later than the others. The environmental and professional stress as well as the interrelations between different hospital members have been suggested, amongst others, as the possible cause of these events.

Authorship↗
PubMed1988

Urinary triiodothyronine excretion.

The purpose of this work was to estimate the 24 h urinary excretion of free and conjugated triiodotironine (T3) using a direct radioimmunoassay and enzyme hydrolysis. Mean urinary values of free and total T3 (mean +/- 1 SD) in euthyroid controls were 2074 +/- 673 and 2819 +/- 809 pmol/24 h respectively. In patients with hyperthyroidism, values of free hormone were about 4.2 times higher than the mean value of the euthyroid controls, and about one-third in patients with hypothyroidism. These results show this measurement to be useful as an indicator of thyroid function. Mean renal clearance of free T3 was 211.6 +/- 62.8 ml/min (mean +/- 1 SD) in euthyroid controls, 260.8 +/- 87.5 ml/ml in hyperthyroid patients and 229 +/- 98.7 ml/min in hypothyroid patients. The data show that T3 renal clearance is, in all cases, greater than glomerular filtration rate, suggesting tubular secretion of T3.

Adult↗
PubMed1988

Defective function of the mononuclear phagocytic system in rats with chronic nephritis. Evidence of a decreased degradation of IgG aggregates by Kupffer cells.

In a model of chronic nephritis induced by daily injections of ovalbumin (OVA), the fate of stable, well-defined heat-aggregated rat IgG (A-IgG) was examined by comparing it to that observed in normal rats of the same age. Following i.v. injection of traced amounts of 125I-A-IgG 0.5 hr after the administration of OVA (Group I), rats with nephritis showed delayed blood clearance (t1/2 = 4.6 +/- 2.3 min) compared to the control group (t1/2 = 2.4 +/- 0.8 min). At this time, the following data were also obtained from rats with nephritis: (i) sections of liver, examined by immunofluorescence, showed rat IgG in Kupffer cells reflecting the presence of immune complexes (IC), as was demonstrated in blood by the Raji cell assay; and (ii) rosette formation of IgG-sensitized Affigel 701 beads with Kupffer cells demonstrated decreased Fc receptor-ligand binding in comparison to those of control rats (percentage rosettes: 18.3 +/- 7.2 versus 40.9 +/- 7.9; P less than 0.01). To assess the dynamics of the mononuclear phagocytic system (MPS) in the uptake of immune complexes, in another set of experiments the A-IgG was administered 18 hr after the injection of OVA (Group II). Although a delayed blood clearance of A-IgG was also observed (t1/2 = 4.1 +/- 1.2 min) there were neither circulating IgG-immune complexes nor IgG deposits in the liver, and the percentage of rosette-forming Kupffer cells was increased (75.6 +/- 7.4%). To explain the apparently discordant results between the t1/2 and percentages of rosette-forming Kupffer cells in Group II, binding assays (at 4 degrees and 37 degrees), endocytosis, and catabolism of labelled A-IgG for Kupffer cells were studied. The binding studies at 4 degrees showed that the number of receptor sites per cell was similar in rats with nephritis (6.5 +/- 3.3 X 10(4] and control rats (7.0 +/- 3.1 X 10(4]. However, in rats with nephritis, the affinity constant Ka was significantly lower (0.86 +/- 0.4/M X 10(8] than in control rats (37.4 +/- 13.9/M X 10(8); P less than 0.01). The endocytosis rates of rats with nephritis were significantly decreased throughout the whole period of study compared to control rats, while the catabolism was only different during the final period of the study. On the whole, these data suggest that rats with induced chronic nephritis present an impairment in the immune clearance of IgG aggregates, probably due to decreased processing by Kupffer cells.

Animals↗
PubMed1985

Transport of calcium, magnesium and strontium by human serum proteins.

The association constant and the maximal binding capacity for calcium, magnesium and strontium to human serum proteins were determined using a wide concentration range by a dialysis technique. The association curves are similar for these elements. Each curve may be subdivided in three parts: the first would correspond to the subfraction tightly bound to protein, the second one shows a linear design implying the association of the element to different binding points which have the same association constant, and the third part shows the saturation of proteins, which is achieved by alkaline-earth concentration about 9 times higher than the physiological ones.

Adolescent↗
PubMed1984

Binding kinetics of monomeric and aggregated IgG to Kupffer cells and hepatocytes of mice.

The binding kinetics of human monomeric IgG and stable heat-aggregated IgG (A-IgG) to Fc receptors of hepatocytes and Kupffer cells isolated from mice was studied. After injection of radiolabelled proteins the 60-70% of hepatic uptake was recovered in parenchymal cells (hepatocytes). In experiments in vitro the A-IgG bound in larger amounts to hepatocytes and Kupffer cells than monomeric IgG. The association rate constants of aggregates were somewhat higher for Kupffer cells than for hepatocytes whereas the percentage uptake of aggregates by Kupffer cells was only 5-15% of that of hepatocytes. The equilibrium constants of aggregates binding to both cells amounted to 0.4-1 X 10(8) M-1 for A-IgG compared with an equilibrium constant for monomeric IgG of 1-2 X 10(7)M-1. The maximum number of IgG and A-IgG molecules bound per cell was higher on hepatocytes (mean 14 X 10(6)) than on Kupffer cells (mean 2 X 10(5)) which is in agreement with the higher binding capacity of hepatocytes for these proteins observed in vivo and in vitro experiments. The ability to compete for receptor binding seemed to reside exclusively in the Fc portion of IgG since F(ab')2 fragments of IgG failed to inhibit labelled monomeric IgG or A-IgG. The receptor seems to be specific for IgG since unlabelled monomeric IgA demonstrated no binding inhibition of labelled IgG or A-IgG on hepatocytes and Kupffer cells. The overall results further suggest that hepatocytes might through Fc receptors play a collaborative role with the mononuclear phagocytic system in the clearance of circulating immune complexes.

Animals↗
PubMed1984

Hepatic and kidney uptake of soluble monomeric and polymeric IgA aggregates.

To investigate the handling of IgA by the mononuclear phagocytic system and by hepatocytes of mice, soluble, similar sized, heat-aggregated monomeric (A-mIgA) and polymeric IgA (ApIgA) were used as akin to IgA immune complexes. The half-life of the clearance from circulation decreased from 2.5 hr to 4.2 min and from 22 min to 1.8 min after aggregation of mIgA and pIgA, respectively. Tissue localization experiments indicated that the liver was the organ predominantly involved in the uptake and catabolism of the proteins injected. The rate of the liver catabolism and/or elimination of aggregated polymeric IgA was the slowest up to 24 hr of injection. Aggregated pIgA was deposited in the kidney in larger amounts than aggregated mIgA. The participation of hepatocytes and nonparenchymal liver cells was determined after isolation and purification of these cells. The four substances injected, pIgA, A-pIgA, mIgA and A-mIgA, were predominantly localized in nonparenchymal cells when the uptake was expressed per volume of cells, due to their lower protein content. However, when the results were expressed cell to cell there was a high ratio of IgA aggregates associated with hepatocytes to nonparenchymal cells. It seems probable, therefore, that hepatocytes are almost exclusively responsible for clearance of IgA aggregates from blood.

Animals↗