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R Alonso

Publications and source records attributed to R Alonso.

At least 163 records · Page 9Linked to original sources
PubMed1993

Interleukin-2 modulates evoked release of [3H]dopamine in rat cultured mesencephalic cells.

Mesencephalic cell cultures were used as a model to investigate the effects of interleukin-2 (IL-2) on evoked release of [3H]dopamine ([3H]DA) and gamma-[3H]-aminobutyric acid ([3H]GABA). At low concentrations (10(-13)-10(-12) M), IL-2 potentiated [3H]DA release evoked by the excitatory amino acids N-methyl-D-aspartate (NMDA) and kainate, whereas higher IL-2 concentrations (10(-9)-10(-8) M) had no effect. IL-2 (10(-14)-10(-8) M) modulated K(+)-evoked [3H]DA release in a biphasic manner, with low concentrations (10(-12)-10(-11) M) of IL-2 potentiating and higher concentrations (10(-9)-10(-8) M) inhibiting K(+)-induced [3H]DA release. IL-2 (10(-14)-10(-8) M) by itself failed to alter spontaneous [3H]DA release. The inhibition by IL-2 of K(+)-evoked [3H]DA release was reversible and not due to neurotoxicity, as preexposure to IL-2 (10(-8) M) had no significant effect on the subsequent ability of dopaminergic cells to take up and to release [3H]DA. Under our experimental conditions, IL-2 (10(-8) M) did not alter Ca(2+)-independent [3H]GABA release evoked by either K+ or NMDA. The results of this study indicate that IL-2 is able to potentiate [3H]DA release evoked by a number of different stimuli, including K+ depolarization and activation of both NMDA and non-NMDA receptor subtypes in mesencephalic cell cultures. IL-2 is active at very low concentrations, a finding that indicates a potent effect of IL-2 on dopaminergic neurons and implicates a physiological role for this cytokine in the modulation of DA release.

Animals↗
PubMed1993

Rapid extraction of high purity chromosomal DNA from Serratia marcescens.

Rapid non-specific degradation of Serratia marcescens DNA extracted with guanidium thiocyanate, occurred within 10 min of incubation with restriction endonuclease enzymes. The described modified method based on chemical and enzymatic deproteinization produced preparations of Ser. marcescens DNA of high yield and quality which did not autodegrade when incubated with restriction endonucleases.

Chromosomes, Bacterial↗
PubMed1993

Ni2+ impairs thrombin-induced signal transduction by acting on the agonist and/or receptor in human platelets.

We have investigated the effect of NiCl2 on platelet activation induced by thrombin, phorbol 12-myristate 13-acetate, and calcium ionophores. Besides blocking Ca2+ influx, NiCl2 inhibited platelet aggregation, intracellular Ca2+ mobilization, and phospholipase C activation induced by thrombin in a dose-dependent manner. In contrast to ionomycin, NiCl2 completely blocked the platelet aggregation and intracellular Ca2+ mobilization induced by A23187. A23187 was not able to translocate Ni2+ across the plasma membrane. Ni2+ also inhibited phorbol myristate acetate-induced platelet aggregation. The results with staurosporine and low NiCl2 concentrations are in agreement in that increases in intracellular Ca2+ concentration and protein kinase C activation are necessary for full platelet activation mediated by thrombin.

Alkaloids↗
PubMed1993

Direct effect of deferoxamine on hemoglobin synthesis in patients on hemodialysis treated with recombinant human erythropoietin.

We have studied the response of hemoglobin (Hb), hematocrit, reticulocytes, mean corpuscular volume, ferritin, serum iron, total iron-binding capacity (TIBC) and the transferrin saturation index in 9 patients on chronic hemodialysis (HD) with minimal aluminum overload who were treated with recombinant human erythropoietin (rHuEPO) when a single dose of deferoxamine (DFO; 40 mg/kg b.w.) was administered. Analytical determinations were performed basally and 48 h, 7 days and 14 days after a DFO test. Hb increased from a basal value of 10 +/- 0.28 to 10.7 +/- 0.33 (p < 0.05), 10.4 +/- 0.33 (p < 0.05) and 10.1 +/- 0.31 g/dl (NS), respectively, and similar increases were seen with the hematocrit. Serum iron increased from 52 +/- 7.62 to 89.2 +/- 14.48 (p < 0.01), 94 +/- 18.73 (p < 0.01) and 85 +/- 14.01 micrograms/dl (p < 0.01), respectively. TIBC and ferritin did not change but the transferrin saturation index increased significantly. DFO produces an immediate improvement of the anemia in HD patients treated with rHuEPO and who have minimal aluminium accumulation: it should be related to an increased iron availability to erythroid precursors either releasing stored iron or decreasing aluminum-bound transferrin.

Aged↗
PubMed1993

[Oligonucleotide probes for the characterization of TEM-1 and TEM-2 beta lactamases in Salmonella strains].

BACKGROUND: The aim of this study was to develop molecular biology techniques as hybridization with oligonucleotide probes to characterize TEM-1 and TEM-2 beta-lactamases in strains of Salmonella spp. METHODS: Twenty seven strains of Salmonella spp. were selected. Twenty six were resistant to ampicillin due to the production of beta-lactamases enzymes of pl of 5.4 and/or 5.6 corresponding to TEM-type. Initially, they were submitted to colony hybridization with a 420 bp. TEM probe obtained from plasmid pBR322. The strains with positive signal were selected to perform colony hybridization and Southern blot with oligonucleotide probes for TEM-1 (Gln 37) and TEM-2 (Lys 37). Finally, polymerase chain reaction technique (PCR) was developed to obtain DNA. RESULTS: Only 17 out of the 26 beta-lactamase producing strains gave positive signals with the TEM intragenic probe. Experiments with the oligonucleotide probes in colony hybridization did not allow us discriminate positive from negative signals. Southern blot of DNA obtained from alkaline lysates did not work as we could not obtain any signals in the filters. To resolve these problems and to obtain enough DNA to perform Southern blot we developed PCR. This way it was able discriminate the bla-TEM-1 from the bla-TEM-2 genes. CONCLUSIONS: PCR technique plus oligonucleotide probes are a good alternative for the specific characterization of TEM-1 and TEM-2 beta-lactamases in Salmonella spp.

Ampicillin Resistance↗
PubMed1993

Ribavirin aerosol: methods for reducing employee exposure.

1. Two new exhaust control methods for scavenging and removing excess ribavirin aerosol were evaluated. Air samples were collected from pediatric intensive care rooms to determine the concentration of ribavirin. 2. Both control methods produced a 99.9% reduction between patient breathing zone concentrations and general room air concentrations. The average room air concentrations of ribavirin were 64 and 37 micrograms/m3 with the control methods in place, compared to average patient breathing zone concentrations of 45,000 and 58,000 micrograms/m3. 3. Additional control methods are reviewed, and published ribavirin environmental monitoring data is summarized. 4. Though the effect on fetal development in humans is not known, it is recommended that occupational exposure to ribavirin aerosol be minimized. A safe level for occupational exposure was calculated to be 91 micrograms/m3 for an 8-hour time weighted average.

Aerosols↗
PubMed1993

[Application of PCR for the detection of mutations in the genes coding for beta-lactamases].

BACKGROUND: The purpose of this study was to develop a satisfactory technique to detect punctual mutations in blaTEM genes. METHODS: The strains [E. coli HB 101 pBR322 (TEM-1), E. coli J62 RP4 (TEM-2)] were submitted to PCR with primers PL1 and PL2 which amplify the genetic region susceptible of punctual mutations. Then, we developed Southern blot and hybridization with oligonucleotide probes (GIn 37, Lys 37 y Thr 261), corresponding to first and last mutations. RESULTS: A region of 841 bp was amplified using the primers previously described. Hybridization experiments with the Thr 261 probe gave positive signal with both strains (both carry the mutation); GIn 37 only hybridized with TEM-1 and Lys 37 only with TEM-2. CONCLUSIONS: The use of primers which amplify all the region susceptible of mutations in blaTEM and oligonucleotide probes allows the specific detection of point modifications in the original genes by the use of digoxigenin-labeled oligonucleotide probes.

Adamantane↗
PubMed1992

Effects of L- and N-type Ca2+ channel antagonists on excitatory amino acid-evoked dopamine release.

In the present study we tested the effect of dihydropyridine (DHP) Ca2+ channel antagonists and of omega-conotoxin GVIA on [3H]dopamine (DA) release evoked by the activation of excitatory amino acid (EAA) receptors in cultures of fetal rat ventral mesencephalon, in order to investigate the role of voltage-sensitive L- and N-type Ca2+ channels in these EAA-mediated processes. Micromolar concentrations (10-30 microM) of DHP L-type Ca2+ channel antagonists inhibited [3H]DA release evoked by N-methyl-D-aspartate (NMDA), kainate, quisqualate or veratridine. [3H]DA release evoked by the L-type Ca2+ channel agonist, Bay K 8644, was inhibited by lower concentrations (0.1-1 microM) of the DHP antagonist, nitrendipine, than was the release evoked by EAAs. The DHP antagonist, (+)-PN 200-110, was more potent than (-)-PN 200-110 in inhibiting [3H]DA release evoked by Bay K 8644, but the two stereoisomers were equipotent in inhibiting NMDA-evoked release. These results indicate that activation of L-type Ca2+ channels is able to evoke [3H]DA release. However activation of L-type channels is not involved in EAA-induced [3H]DA release and therefore inhibition of EAA-induced [3H]DA release by micromolar concentrations of DHPs must be mediated by actions other than inhibition of L-type Ca2+ channels. omega-Conotoxin GVIA (3 microM) had no effect on [3H]DA release evoked by Bay K 8644, indicating that the toxin may selectively inhibit N-type channels in this preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Effect of dietary monounsaturated fatty acids on plasma lipoproteins and apolipoproteins in women.

To determine the effects of dietary fat saturation on plasma lipoproteins, we studied 21 free-living normolipidemic women (13 pre- and 8 postmenopausal) on three consecutive diet periods. During the first 4 wk they consumed a saturated diet rich in palm oil and butter [19% saturated fatty acids (S), 14% monounsaturated fatty acids (M), and 3.5% polyunsaturated fatty acids (P)], followed by 6 wk of a monounsaturated diet rich in olive oil (11% S, 22% M, and 3.6% P), and 6 wk of a polyunsaturated diet rich in sunflower oil (10.7% S, 12.5% M, and 12.8% P). Compared with the diet rich in saturated fatty acids, both diets rich in unsaturated fatty acids had similar lowering effects on total and low-density-lipoprotein cholesterol. High-density lipoprotein cholesterol and apolipoprotein A-I were higher in the monounsaturated-rich period than in the polyunsaturated-rich (10.5% and 12.7% respectively, P less than 0.001) and the saturated-rich period (5.3%, and 7.9%, respectively, P less than 0.05). These effects were independent of menopause status. Our data show that at this level of fat intake (36% as calories), a monounsaturated-rich diet results in a less atherogenic lipid profile than either polyunsaturated- or saturated-rich diets.

Adult↗
PubMed1992

Control of neck nodes in squamous cell carcinoma of the head and neck by radiotherapy: prognostic factors.

313 patients with cervical metastases from a squamous carcinoma of the head and neck treated with radiotherapy, were studied by means of a multivariant analysis in order to determine the prognostic factors for cure. These were: lymph node response to irradiation (P = 0.0000), size of node (P = 0.0000), radiotherapy dose (P = 0.0037), condition of the primary (controlled vs non-controlled) (P = 0.0015), recurrent cervical metastases post-surgery (P = 0.0286).

Adolescent↗
PubMed1992

Determination of kinetic properties of serotonin-N-acetyltransferase in bovine pineal gland using HPLC with fluorimetric detection.

The determination of serotonin-N-acetyltransferase (NAT) activity in the bovine pineal gland and other rat tissues was based upon the separation and detection of N-acetyltryptamine formed from tryptamine and acetyl CoA by means of high performance liquid chromatography with fluorimetric detection. In the bovine pineal the enzyme exhibited a Km value of 31.45 +/- 4.98 microM and a Vmax value of 30.90 +/- 1.18 pmol N-acetyltryptamine/min/mg protein for tryptamine, and a Km value of 28.72 +/- 7.50 microM and a Vmax value of 25.90 +/- 1.50 pmol N-acetyltryptamine/min/mg protein for acetyl CoA. The present method is simple, allows the determination of NAT activity from a variety of enzyme sources, has application to pharmacological studies of NAT regulation in tissue cultures, and provides an alternative to current radioenzymatic assays.

Animals↗
PubMed1992

[Molecular study of ampicillin resistance in clinical isolates of Salmonella].

BACKGROUND: The purpose of this work was to study the molecular basis of beta-lactamase production in ampicillin-resistant strains of Salmonella spp. METHODS: It was performed analytical isoelectric focusing of beta-lactamases produced by a group of 33 strains selected in basis of their resistance phenotype. Plasmid profile analysis and assays of transferable drug resistance were developed. The study was completed by hybridization experiments with an intragenic TEM probe which allowed the location of the bla-TEM gene. RESULTS: By analytical isoelectrofocusing we found that 26 out of the 27 ampicillin-resistant strains produced beta-lactamases with pl 5.4 and/or 5.6 corresponding to TEM-1 and/or TEM-2 type. Analysis of plasmid DNA revealed in almost all strains plasmids ranging in size from 1.1 to 125 Mdal. This plasmids were responsible of the resistance and, moreover, were able to transfer the resistance by conjugation mechanisms. Southern blot analysis detected the gene that code the TEM beta-lactamase at the 125, 8 and 5.8 Mdal plasmids. CONCLUSIONS: Resistance to ampicillin in the strains of Salmonella studied was due to the presence of TEM type beta-lactamases coded by conjugative plasmids. These plasmids coded also resistance to other antimicrobial agents. Our results showed that the use of a DNA probe to the detect TEM-type beta-lactamases using a non radioactive probe, could be a suitable alternative to isoelectric focusing.

Ampicillin Resistance↗
PubMed1992

Cholinergic mechanisms involved in the effect of intraduodenal ethanol on exocrine pancreatic secretion.

The effect of intraduodenal ethanol on exocrine pancreas of the rat in basal conditions has been studied. The pancreatic flow rate significantly increased to a maximum of 148% of basal after intraduodenal ethanol whereas only slight increases of protein output were observed. Ethanol perfusion in previously atropinized animals also elicited a significant increase of the flow rate up to a maximum of 177% of basal values but this increase appeared later than that observed in non-atropinized animals. Our results show that the ethanol action is successively stimulant followed by a simultaneously dual and antagonic effect (stimulant and inhibitory). Furthermore, this ethanol effect is mediated by cholinergic mechanisms. Finally, no effect of ethanol on portal plasma secretin and VIP levels was observed in atropinized or non-atropinized animals.

Animals↗
PubMed1992

[Digoxigenin-labelled probes for detection of TEM-type beta-lactamases using the PCR technique].

BACKGROUND: Production of DNA probes is time-consuming and inefficient. We have developed a method for the obtention of digoxigenin-labeled probes to detect TEM-type betalactamases using the polymerase chain reaction. The amplification product was a 516 bp fragment internal to bla-TEM-1 from pBR 322. METHODS: The techniques developed included extraction of plasmid DNA by lisis by alkali, electroelution, electrophoresis in agarose gels, polymerase chain reaction and hydridization with a DNA probe digoxigenin labeled. RESULTS: We obtained by polymerase chain reaction 1500 ng of probe using 1 ng of target DNA. Developing classic methods the amount of probe was 75 ng from 1 microgram of target DNA. The time to obtain the probe was 3 hours, instead of a week with other methods. CONCLUSIONS: We conclude that polymerase chain reaction is a good alternative to classic methods to obtain digoxigenin-labeled DNA probes.

Base Sequence↗
PubMed1992

[Antimicrobial resistance in strains of Salmonella enterica isolated in the Hospital de Basurto (Bilbao) from 1987 to 1990].

BACKGROUND: Rate development of antimicrobial resistance of Salmonella strains in Hospital Basurto of Bilbao from 1987 to 1990 and to study their resistance mechanism. METHODS: The antimicrobial resistance for all strains isolated (1201 strains) was performed by means of a agar-diffusion test. We selected 32 multi-resistant strains for additional study (MIC, conjugation, IEF, and plasmid profile). RESULTS: The most frequent isolated serotypes were S. enteritidis (79.01%), S. typhimurium (8.5%) and Salmonella serogroup C1 (6.9%). The resistance to one or more of 17 antimicrobial rose significantly: 9.6% in 1987; 10.25% in 1988; 16.45% in 1989 and 13.73% in 1990. The percentage of resistant serotypes were: S. typhimurium (40.2%); Salmonella serogroup B (31.8%); Salmonella serogroup C1 (16.8%); Salmonella serogroup D1 (13.04%); Salmonella serogroup C2 (9.09%) and S. enteritidis (8.4%). In 27 multi-resistant strains and their transconjugants, beta-lactamase bands with a pl: 5.4 and/or 5.6 compatible with TEM-1 and/or TEM-2 were observed. Also, these strains carried a plasmid of high molecular weight (125 MD). CONCLUSIONS: Although, the resistance of Salmonella is not a serious problem in our environment this situation is raising progressively with a greater number of strains with plasmid mediated beta-lactamases. So, the antimicrobial policy will be more severe and righ in both hospital and extrahospital surrounding.

Bacterial Proteins↗
PubMed1991

Effects of serotonergic denervation on the density and plasticity of brain muscarinic receptors in the rat.

This study investigated whether serotonergic lesion may affect density, sensitivity, and plasticity of muscarinic receptors in hippocampus and cerebral cortex. Intracerebroventricular injection of 5,7-dihydroxytryptamine (5,7-DHT) in rats produced a 90% reduction in cortical and hippocampal 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents. In these brain areas, the 5,7-DHT lesion did not affect the overall density of muscarinic receptors or those of M1 and non-M1 muscarinic receptor subtypes as assayed using [3H]N-methylscopolamine ([3H]NMS), [3H]pirenzepine, and [3H]NMS in the presence of pirenzepine, respectively. In addition, the binding of the muscarinic agonist [3H]oxotremorine-M (OXO-M), taken as an indirect index of coupling efficiency of non-M1 receptors with G-proteins, did not change significantly in cortex and hippocampus of 5,7-DHT-lesioned rats. Similarly, carbachol-induced accumulation of [3H]inositol phosphates (InPs) in hippocampal miniprisms showed no significant differences between tissues from 5,7-DHT-lesioned and sham-operated rats. In sham-operated rats, an intraperitoneal (i.p.) injection of scopolamine (10 mg/kg once daily) during 21 days caused an increased density of [3H]NMS binding sites in cortex (+20%) and hippocampus (+26%). This up-regulation was restricted to non-M1 receptors subtypes. In 5,7-DHT-lesioned rats, chronic scopolamine failed to modify significantly the density of cortical or hippocampal M1 or non-M1 receptors. These results suggest 1) that 5-HT denervation did not affect the density and sensitivity of muscarinic receptors and 2) that the ability of cortical and hippocampal non-M1 receptors to up-regulate following repeated injection of scopolamine requires the integrity of 5-HT neurons terminating in these brain structures.

5,7-Dihydroxytryptamine↗