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Biomedical subjects

A Lorenzo

Publications and source records attributed to A Lorenzo.

At least 19 recordsLinked to original sources
PubMed1992

Time lapse study of neurite growth in hypothalamic dissociated neurons in culture: sex differences and estrogen effects.

Cultures of dissociated hypothalamic cells taken from rat fetuses of 19 days of gestation were studied using time-lapse recording and sequential microphotography from 1 to 5 days in vitro (DIV) and at 7 and 21 DIV. Cultures were seeded with cells taken from fetuses grouped by sex or sexually mixed; experimental cultures were raised in medium containing 17-beta-estradiol 100 nM (E2). Cells were plated on poly-D-lysine-coated coverslips at a culture density of approximately 4,000 cells/cm2. Immunocytochemistry of cell cultures was performed using a Tau monoclonal antibody (clone Tau-1 PC1C6) and a monoclonal antibody against MAP-2 (clone AP-20). Cells started to produce lamellipodia and neuritic processes approximately 4 hr after plating. Forty-eight hours later a few neurons had defined their morphological polarity by the differentiation of an axon-like process that grows faster than the others; at 5 DIV almost all neurons had defined their axons. At this time, monoclonal antibody against MAP-2 clearly stained soma and dendrites, but not axons. Tau immunoreactivity (lots CCA101 and CCA101N from Boeringher Mannheim) was differentially distributed, with a clear predominance in axon and soma. Results on the morphometric analysis of control and E2 treated neurons provide direct evidence for the existence of sex related differences in the neurite outgrowth response of hypothalamic neurons, since cultured neurons taken from female fetuses differentiated axons later and had fewer primary neurites and shorter dendrites than neurons taken from male fetuses or sexually mixed cultures. Also, it was demonstrated in living neurons that E2 effectively enhances outgrowth and elongation in axons. The frequency distribution curves of axonal length for control and E2 treated cultures was unimodal, suggesting that the effect of E2 was a uniform increase in the axonal length of all neurons. The structural differences between neurons from both sexes and the changes induced by E2 may contribute to explain the differences in brain function found between the sexes.

Animals↗
PubMed1992

Amygdala neurons in vitro: neurite growth and effects of estradiol.

Dissociated cell cultures from embryonic rat medial amygdala were studied using sequential photography and immunocytochemical staining for cytoskeletal proteins and substance P (sP). Cultures were seeded with cells taken from fetuses grouped by sex; experimental cultures were raised in medium containing 17-beta-estradiol (E2). Forty-eight hours after plating a few neurons begin to define their morphological polarity by the differentiation of an axon-like process; at 5 days in vitro (DIV) almost all neurons had developed an axon. Tapering, daughter branch ratio and branch power coefficient coincided with identification of dendrites which could be confirmed by retrospective analysis of immunocytochemically stained cultures: at 5 DIV MAP-2 was restricted to dendrites whereas Tau immunoreactivity was differentially localized with a clear predominance in the axon. At 21 DIV neuronal shape parameters were strikingly like those of amygdaloid neurons in vivo. It was demonstrated in living neurons that E2 increased total dendritic length and that this is due to increased ramification of third or higher order dendritic segments whose individual lengths are not different from controls. Densitometric measurement of MAP-2 stained neurons showed a highly significant increase of immunoreactive material in cells grown in the presence of E2; readings for alpha-tubulin were not different between controls and E2 treated cultures. The effect of E2 on dendritic length was just as manifest in sP-positive as in sP-negative neurons. No sexual differences in morphological parameters, growth characteristics or effects of E2 were found in neurons taken from female fetuses versus neurons from male fetuses. The significance of these results for the generation of sexual differences in the amygdala in vivo is discussed and contrasted with reported results on the effects of E2 in cultures of different neural regions.

Amygdala↗
PubMed1992

[Beta-thromboglobulin levels and atherosclerosis. Its relationship with the presence of risk factors].

In order to evaluate whether plasma beta-thromboglobulin (as a marker of the degree of platelet function) in patients presenting clinically evident atherosclerosis is related to the presence or absence of different risk factors (smoking habit, arterial hypertension, hypercholesterolemia, diabetes, hypertriglyceridemia, obesity, hyperuricemia, alcoholism), 40 patients have been studied in whom mean beta-thromboglobulin levels was 54 +/- 25.56 ng/ml, which is very superior to levels considered normal. However, the presence of one or more risk factors did not lead to significant variations in b-thromboglobulin concentrations, and no differences were found either when each risk factor was considered separately. The positive correlation (r = 0.98; p less than 0.01) between beta-thromboglobulin and apo B levels is highlighted. The results suggest that platelet hyperfunction seems to be due to a greater extent to the atherosclerotic process rather than to the existence of a particular risk factor.

Aged↗
PubMed1991

[Ceruloplasmin levels in patients with chronic obstructive bronchopneumopathy].

The seric levels of ceruloplasmin in a group of 20 patients suffering of chronic obstructive lung disease were studied. Levels in this group of patients (51.42 +/- 11.15 mg/dl) (p less than 0.005) were significantly higher than those of the control group (36.59 +/- 13.37 mg/dl). There was no correlation between ceruloplasmin levels and PaO2, PaCO2, SaO2, HCO3- measurements. Results show a possible oxidation reaction; owing to the fact that ceruloplasmin is a general oxidase which, combined with an antioxidant stimulus of patients with chronic respiratory insufficiency, can produce this reaction.

Aged↗
PubMed1990

[Escape rhythms after ablation of the atrioventricular junction and implantation of a pacemaker].

Escape rhythms characteristics after successful catheter ablation of the atrioventricular junction and intentional complete heart block were compared with those due to others etiologies as well as the advantage of the posterior implantation of a rate responsive pacemaker (VVIR). In 22 patients, 9 men and 13 women, with permanent AV block after fulguration and follow-up periods from 4 to 58 months, escape rhythms data studied during the procedure and at short and long-term periods, showed the following characteristics: 1) Classical parameters of valuation are not as a whole useful to evaluate subsidiary escape rhythms after electrical fulguration of the atrioventricular junction system. 2) The QRS morphology of the escape rhythm exhibited frequently right or left bundle branch block and specially the former. 3) Spontaneous variability of the escape rhythm recovery time makes this parameter unreliable. 4) Electrophysiological parameters previous to the shock and energy delivery do not predict the origin and characteristics of the subsidiary escape rhythms. 5) Active ventricular arrhythmias appearing immediately postshock are unrelated with any subsequent complication. 6) Permanent pacing increases pacemaker dependency at least temporarily. In 15 of 22 patients, a rate responsive multiprogrammable pacemaker controlled by QT interval was implanted. Cardiac performance and life-quality was improved in these patients due to the addition of several factors: 1) Control of the tachyarrhythmias. 2) Elimination of antiarrhythmic drugs and their side-effects on ventricular function. 3) Self-regulation of cardiac rate through permanent stimulation with a QT sensitive rate responsive pacemaker.

Adult↗
PubMed1990

[Results of the functional tests using calcitonin in patients with chronic diffuse hepatopathy].

A group of ten patients suffering cirrhosis who were treated with 100 U/l of calcitonin was studied with the aim of knowing whether in patients with cirrhosis the calcitonin is able to provoke the usual characteristic biologic modifications on the basis of the knowledge of their hormonal high levels accompanied of oesteopenia. Regarding their baseline determinations, no statistically significant modifications have been observed in calcium, phosphorous, alkaline phosphatase or its thermostable and thermolabile fractions, magnesium, uric acid and creatinine plasma concentrations respectively. This absence of a biological response to calcitonin could be due either to a numeric or functional damage of the hormone receptors or a diminished biodisponibility, although there are facts suggesting a lesser hormone biopotenciality in these patients.

Calcitonin↗
PubMed1989

Rat blood and brain amino acid pattern in short term experimental diabetes.

Some serum and brain amino acid variations occurring in animals with short term streptozotocin-diabetes (24 h) are studied in this work. Diabetic animals showed an increase in serum of the three branched-chain amino acids as well as an increase in free tryptophan, besides a decrease in total serum tryptophan and in the tryptophan/competitor amino acids ratio. In brain, the three branched-chain amino acids increased, but there were no variation in whole brain tryptophan. Nevertheless, by studying levels of tryptophan in different brain regions, an increase in medulla-pons was recorded. This circumstance could be explained by the increase in free serum tryptophan levels, in agreement with several authors who assign this reason for brain tryptophan.

Amino Acids↗
PubMed1988

Verapamil injections in the peripeduncular nucleus suppress multiunit evoked activity and sexual receptivity in female rats.

Using a combination of injection cannula and recording electrode, the effect of 1 microliter of 3 mM verapamil upon the multiunit responses evoked in the peripeduncular nucleus (PPN) by electric stimuli applied to the pudendal nerves in urethane anesthetized proestrous female rats was studied in 9 experiments. It was observed that in 6 cases responses were suppressed after the injection and in 2 other cases there was a marked decrease, whereas no change was observed in 1 case. Similar injections of vehicle (saline) produced no change (7 rats) or small and short lasting depression of evoked activity (4 rats). Similar injections of verapamil applied to a region of the mesencephalic reticular formation caudal to the PPN, presumably containing fibers that carry evoked activity towards the PPN, had no effect on evoked multiunit activity in the PPN. Injection of 2% Xylocaine in the same site in the same animal eliminated the evoked responses. These experiments support our hypothesis that verapamil suppressed evoked responses in the PPN blocking Ca++-dependent release of neurotransmitter at local synapsis, without interfering with fiber conduction of neural activity. Based on this assumption we used identical injections to test the hypothesis that activation of neurons in the PPN is necessary for the performance of lordotic behavior in ovariectomized rats primed with estradiol benzoate. Guide cannulae aimed at the PPN were implanted in castrated females which were then primed with enough estradiol benzoate to induce sexual receptivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The role of aldosterone in water and electrolyte transport across the colonic epithelium of the lizard, Gallotia galloti.

1. The effects of D-aldosterone on the electrical properties and ionic transport have been analysed (in vitro) in the colonic epithelium of the lizard, Gallotia galloti. 2. The injection of 30 g of D-aldosterone induced a significant rise of plasma aldosterone concentration, sustained for 4 hr after administration. 3. Intraperitoneal injections of D-aldosterone caused a slight reduction of transmural potential difference (PD) and short-circuit current (Isc). 4. Net absorption of Na+ across the colon from aldosterone-treated lizards did not increase when compared to colon from normal lizards. Cl- absorption was increased in treated lizards. 5. Addition of mucosal barium to treated tissues brought about a sustained increase of PD and Isc. 6. The absorption of fluid in normal lizards was reversed to fluid secretion in treated lizards. 7. The effects of D-aldosterone on lizard colon are compared with those reported for the colon of mammals and birds.

Aldosterone↗