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Biomedical subjects

G Alonso

Publications and source records attributed to G Alonso.

177 records · Page 10Linked to original sources
PubMed1968

ATP splitting and calcium binding by brain microsomes measured with a rapid perfusion method.

Rat brain microsomes, immobilized on a filter, were perfused with ATP-containing solutions in a device which made possible rapid change of perfusion media and frequent sampling of effluent. Inorganic phosphate production could be measured 10 times per sec. When ATP, sodium, or potassium was absent from the first perfusion medium and present in a second, and introduced without interrupting flow, phosphate output rose within a few tenths of a second. Inhibition by ouabain began within 0.3 sec but did not become maximal for at least 10 sec. Rapid binding of ouabain was minimal or absent, as was rapid release of ouabain on introducing potassium abruptly. Although the preparation bound some calcium reversibly, no measurable uptake of calcium occurred coincident with activation by ATP or by potassium, and no measurable release of calcium occurred coincident with the onset of ouabain inhibition. However, activation by sodium was consistently associated with simultaneous release (within < 1 sec) of calcium, averaging 46 pmole per mg of protein. Calcium release in response to sodium also occurred in the absence of ATP or in the presence of ouabain. At 0 degrees C sodium produced neither activation nor calcium release. The results are consistent with the possibility that sodium and calcium are competitively bound, even in the absence of ATP, to an active site on the enzyme distinct from the sites of potassium activation or glycoside inhibition.

Adenosine Triphosphate↗
PubMedDate not supplied

Differential organization of synapses immunoreactive to phenylethanolamine-N-methyltransferase or neuropeptide Y in the parvicellular compartments of the hypothalamic paraventricular nucleus of the rat.

The parvicellular compartments of the paraventricular nucleus of the hypothalamus (pPVN) contains particularly high concentrations of neuropeptide (NPY)-containing fibres of two main cellular origins including (i) neurons of the medulla oblongata, most of which co-store phenylethanolamine-N-methyltransferase (PNMT), the enzyme characterizing adrenergic neurons, and (ii) non-catecholaminergic neurons of the mediobasal hypothalamus. The aim of the present study is to compare the fine organization of the two types of axons terminating in the pPVN. Immunocytochemistry at light and electron microscope levels was used to study both the density and the ultrastructural organization of NPY- and PNMT-immunoreactive fibres in the pPVN of animals bearing surgical lesions disrupting axonal pathways from the hindbrain or from the sublying mediobasal hypothalamus. The brainstem knife-cut induced a strong decrease (65%) in the numerical density of PNMT fibres innervating the pPVN, but was without significant effects on the density of NPY fibres. On the other hand, the hypothalamic knife-cut induced an 80% decrease in the density of NPY fibres within the PVN without affecting the number of PNMT fibres. The electron microscope study showed that in the control pPVN contralateral to the lesions, the majority (64%) of PNMT synapses were asymmetric axo-dendritic synapses, whereas the majority (67%) of NPY synapses form symmetric contacts with both dendrites and perikarya of the hypothalamic nucleus. By contrast, after a hypothalamic knife-cut, the majority (66%) of NPY synapses identified in the pPVN exhibited features of asymmetric synapses. These data indicate that the large majority of NPY-immunoreactive fibres detected within the pPVN arise from non-catecholaminergic neurons located in the mediobasal hypothalamus and mainly form symmetric synapses on neurons of the pPVN, whereas only a minority of them arise from hindbrain regions, and like PNMT fibres innervating this nucleus preferentially form asymmetric axo-dendritic synapses.

Animals↗
PubMedDate not supplied

Control of Trypanosoma cruzi epimastigote motility through the nitric oxide pathway.

Trypanosoma cruzi epimastigote motility can be enhanced by addition of L-arginine, to the culture. This effect is blocked by N-methyl-L-arginine, a competitive inhibitor of the nitric oxide synthase. N-methyl-D-aspartate and L-glutamate, two agonists of the NMDA/L-glutamate receptor, also enhanced motility. This stimulation is blocked by MK-801 a noncompetitive antagonist of the NMDA receptor. In addition, sodium nitroprusside, a guanylyl cyclase stimulator and 8-Br-cyclic GMP, and analog of cyclic GMP, also stimulated epimastigote motility. It is suggested that an increase of intracellular cyclic GMP levels mediated by nitric oxide may be responsible for the increase in epimastigote motility.

Amino Acids↗
PubMedDate not supplied

Growth in four patients on combined treatment with LHRH analogue and growth hormone after renal transplantation.

Four short pubertal boys were treated with LHRHa (leuprolide) and GH after renal transplantation, and followed until adult height. This combined therapy was not successful in increasing growth. Although this study must be considered preliminary because of the small number of patients and the lack of a matched control group, it shows for the first time that this combined therapy (GH + LHRHa) administered to short, pubertal boys after renal transplantation was not successful in increasing growth. Further studies are required to reach definitive conclusions.

Body Height↗
PubMedDate not supplied

Thyroid dysfunction and high thyroid stimulating hormone levels in children with Down's syndrome.

UNLABELLED: In order to delineate the spectrum of thyroid abnormalities in children with Down's syndrome (DS), first visit height data (SDS) and serum TSH, T4 and antiperoxidase antibodies concentrations were retrospectively evaluated in 137 children (71 girls) with DS (0.04-16 years). RESULTS: Congenital hypothyroidism was detected in 2.9% of patients. Thyroid disease occurred in 9%: four hyperthyroidism and eight hypothyroidism. Overt thyroid disease was always related to thyroid autoimmunity. The remaining 121 patients had normal T4 levels but increased mean TSH compared with controls (4.7 +/- 2.8 vs 2.3 +/- 1.3 mU/l). According to TSH levels, they were divided into two groups: G1 (n = 68) with normal TSH (<5 mU/l), and G2 (n = 53) with high TSH (> 5 mU/l). T4 levels were significantly lower in G2 (p < 0.01 vs G1 and controls). Height SDS was not different. CONCLUSIONS: Thyroid disorders are frequent in children with DS. Subtle thyroid abnormalities found in patients with DS with no evidence of clinical dysfunction need further investigation to demonstrate whether there is a need for therapeutic intervention.

Adolescent↗
PubMedDate not supplied

Trypanosomatidae codon usage and GC distribution.

A study of Trypanosomatidae GC distribution and codon usage is presented. The codon usage patterns in coincidence with the phylogenetical data are similar in Crithidia and Leishmania, whereas they are more divergent in Trypanosoma brucei and T. cruzi. The analysis of the GC mutational pressure in these organisms reveals that T. brucei, and to a lesser extent T. cruzi, have evolved towards a more balanced use of all bases, whereas Leishmania and Crithidia retain features of a primeval genetic apparatus. Tables with the approximated GC mutational pressure in homologous genes, and codon usage in Trypanosomatidae are presented.

Animals↗
PubMedDate not supplied

Comparison of relative renal function measured with either 99mTc-DTPA or 99mTc-EC dynamic scintigraphies with that measured with 99mTc-DMSA static scintigraphy.

OBJECTIVE: The aim of this study was to compare the renal function measured with either 99mTc-DTPA or 99mTc-EC dynamic scintigraphies with that measured using 99mTc-DMSA static scintigraphy. METHODS: the values of relative renal function measured in 111 renal dynamic scintigraphies performed either with 99mTc-DTPA (55 studies) or with 99mTc-EC (56 studies) were compared with the relative function measured using 99mTc-DMSA static scintigraphy performed within a 1-month period. The comparisons were performed using Wilcoxon signed rank test. The number of 99mTc-DTPA and 99mTc-EC studies that presented relative renal function different by more than 5% from that measured with 99mTc-DMSA, using chi square test were also compared. RESULTS: the relative renal function measured with 99mTc-EC is not statistically different from that measured with 99mTc-DMSA (p = 0.97). The relative renal function measured with 99mTc-DTPA was statistically different from that measured using 99mTc-DMSA, but with a borderline statistical significance (p = 0.05). The number of studies with relative renal function different by more than 5% from that measured with 99mTc-DMSA is higher for the 99mTc-DTPA scintigraphy (p = 0.04) than for 99mTc-EC. CONCLUSION: the relative renal function measured with 99mTc-EC dynamic scintigraphy is comparable with that measured with 99mTc-DMSA static scintigraphy, while the relative renal function measured with 99mTc-DTPA dynamic scintigraphy presents a significant statistical difference from that measured with 99mTc-DMSA static scintigraphy.

Adolescent↗
PubMedDate not supplied

[Restandardization of thyroid uptake indices in patients with euthyroidism using 131I].

The authors studied 454 patients in order to review the thyroid uptake pattern in São Paulo. They were submitted to clinical examination and hormone dosages (T3, T4 and TSH). Two hundred and fifty-four patients (55.9%) were excluded because they had hormonal dosages out of the normal range of substernal, diffuse and multinodular goiter, or were younger than 12. The 200 remaining patients (44.1%) were included in the euthyroidism group and the results were as follows: 2 hours thyroid uptake = 3 to 12%; 24 hour thyroid uptake = 8 to 32%.

Adolescent↗
PubMedDate not supplied

[A comparative study of the osmoregulating system in the hamsters Phodopus roborovskii and Phodopus sungorus].

The hamster Phodopus roborovskii is adapted to live in desert, Phodopus sungorus in less arid regions. Hamsters of both species have rather close values of blood serum osmolality and ion concentration, after dehydration the value of urine osmolality is found to be equally high. The microdissection of the kidney did not reveal any difference in the structure and arrangement of nephrons in cortex and medulla. According to the results of immunocytochemical analysis of the hypothalamo-hypophyseal neurosecretory system of hamster Phodopus roborovskii, compared to Phodopus sungorus, has a smaller quantity of vasopressin-positive neurons, which is likely to be a result of a release of larger quantities of vasopressin in long-term dehydration. It is suggested that of importance in the animal adaptation to life in arid condition may be not only morphofunctional reorganization of kidney but also of the hypothalamo-hypophyseal system which is involved in permanent secretion of vasopressin.

Animals↗
PubMedDate not supplied

Results of two sequential phase II studies of interleukin-2 (IL2) in metastatic renal cell carcinoma and melanoma: high-dose continuous intravenous IL2 infusion and subcutaneous IL2 administration in combination with alpha interferon.

The results of two sequential trials, the first one with high dose interleukin 2 (IL2) by continuous intravenous infusion and the second one with subcutaneous IL2 and alpha-interferon (alpha IFN), performed in consecutive patients with metastatic melanoma and renal carcinoma at the Clinica Universitaria de Navarra are presented. In the high-dose continuous IL2 trial, recombinant IL2, 18 x 10(6) IU/m2, was administered daily by continuous infusion five days a week for two weeks, and the treatment cycle was repeated after a rest of 2 weeks. Twenty two patients were treated and objective responses were observed in 3 (13.3%). Toxicity was frequent and severe, and all but one required dose reduction. The mortality rate was 9% (2/22). In the subcutaneous IL2 and alpha IFN trial, subcutaneous IL2, 4.8 x 10(6) IU/m2, was administered daily, five days a week, for 3 consecutive weeks. IL2 dose was given every 8 hours on the first day and every 12 hours on the second day, as a loading induction dose. Concomitant alpha-IFN, 3 x 10(6) IU/m2 was given subcutaneously once a day on days 1, 3 and 5 weekly each week for the duration of IL2 therapy. Of the 24 patients treated with this combination, 3 partial responses were noticed (12.5%) and the toxicity was mild to moderate. These results suggest that both, IL2 alone or IL2 in combination with alpha-IFN are minimally active and that any improvement in tolerance might impair its antitumor activity.

Adolescent↗