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Biomedical subjects

R Alonso

Publications and source records attributed to R Alonso.

At least 127 records · Page 7Linked to original sources
PubMed1997

Thymostimulin increases natural cytotoxic activity in patients with breast cancer.

The effect of thymostimulin on the Natural Killer (NK) cytotoxic activity of peripheral blood mononuclear cells (PBMC) was investigated in 15 patients with breast cancer after finishing or during chemotherapy (CAF) and in 10 healthy controls. PBMC from these subjects were incubated in the presence of thymostimulin for varying periods of time (18 h or 5 days), and then used as effector cells against 51Cr-radiolabeled NK-sensitive (K-562) and NK-resistant (JY) target cells in cytotoxicity assays. No significant differences were observed between the NK-activity from breast cancer patients and healthy controls. Thymostimulin induced a dose- and time-dependent cytotoxic enhancing effect on the cytotoxic activity of PBMC from these patients against NK-sensitive K562 target cells. The thymostimulin (1000 ng/ml) significantly enhanced cytotoxic activity in PBMC from breast cancer patients who had previously received chemotherapy (p = 0.0277) against NK-sensitive cells. This increase was not statistically significant neither in PBMC from patients receiving chemotherapy nor in healthy controls (p > 0.05 in both cases). The incubation of PBMC from patients with breast cancer was not associated to a significant enhancement of the cytotoxic activity against NK-resistant target cells (p > 0.05). We also found that thymostimulin could synergize with interleukin-2 in inducing NK cytotoxic activity in PBMC after 18 h of culture (p = 0.0277). In conclusion, we have demonstrated that thymostimulin enhances the natural killer cytotoxic activity of PBMC from patients with breast cancer who have previously received chemotherapy.

Adjuvants, Immunologic↗
PubMed1997

Effects of dietary fat saturation on eicosanoid production, platelet aggregation and blood pressure.

The effects of dietary fat saturation on eicosanoid urinary excretion, platelet aggregation (PA) and blood pressure (BP) were studied in 42 healthy subjects. They consumed four consecutive diets differing in their fat saturation [saturated (SFA); monounsaturated (MUFA); polyunsaturated n-6 (PUFA n-6); and polyunsaturated n-6/n-3, (PUFA n-3)]. Each diet period lasted 5 weeks. There were no differences in 24-h 2,3-dinor-6- keto-prostaglandin F1 alpha excretion among dietary periods. A significant effect was noted regarding the excretion of 11-dehydro-thromboxane B2 (P < 0.0001). During the PUFA n-6 phase the excretion was significantly higher than during SFA and MUFA periods. Dietary fatty acid composition had a significant effect on ADP (1 mumolL-1) and collagen (2 mgL-1) induced PA. Dietary fat also had a significant effect on systolic and diastolic blood pressure (P < 0.0001). Both were significantly higher during the SFA period than during the other three periods. Our findings suggest that changes in dietary fatty acids may have mild, but significant, effects on eicosanoid production, platelet aggregation and blood pressure.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Outbreak among HIV-infected patients of Staphylococcus aureus resistant to cotrimoxazole and methicillin.

OBJECTIVE: To describe an outbreak of trimethoprim-sulfamethoxazole (cotrimoxazole)-resistant and methicillin-resistant Staphylococcus aureus (CMRSA) in a unit housing patients infected with the human immunodeficiency virus (HIV). DESIGN: Prospective study involving patients colonized or infected with CMRSA. PATIENTS: 15 hospitalized patients with cultures positive for CMRSA. METHODS: Isolates of CMRSA were collected and characterized. Molecular typing of the epidemic strains was carried out after total DNA extraction by restriction endonuclease analysis and random amplification of polymorphic DNA. RESULTS: The epidemic was brought under control with the reinforcement of nosocomial transmission measures and with systematic nasal decontamination with mupirocin of all patients admitted to the HIV unit. Molecular typing techniques showed the existence of two epidemic strains: strain A was present in the 12 patients admitted to the HIV unit and strain B in the remaining 3 patients hospitalized elsewhere. CONCLUSIONS: Cotrimoxazole may no longer be a reliable and effective alternative for glycopeptides in patients with infection caused by MRSA strains, and HIV units should be particularly alert for CMRSA strains.

Adult↗
PubMed1997

Monounsaturated and polyunsaturated n-6 fatty acid-enriched diets modify LDL oxidation and decrease human coronary smooth muscle cell DNA synthesis.

Proliferation of smooth muscle cells (SMCs) plays an important role in atherosclerotic lesion progression. The purpose of this investigation was to examine the effect of diets differing in fatty acid composition on human coronary SMC entry in the cell proliferation cycle. Twenty-four healthy men and women were placed on four consecutive diets lasting 5 weeks each: (1) saturated fatty acid (SFA)-rich diet with palm oil; (2) monounsaturated fatty acid (MUFA)-rich diet with olive oil; (3) polyunsaturated fatty acid (PUFA) n-6-rich diet with sunflower oil; and (4) PUFA n-3-rich diet (3.8 g/d). All diets supplied 35% of calories as fat. Compared with the SFA diet, all unsaturated diets reduced LDL cholesterol. Resistance of LDL to oxidative modification was significantly increased during the MUFA period (P < .05). Human coronary SMCs were cultured and induced by sera derived from the different groups. 3H-Thymidine incorporation into doubling DNA was significantly (P < .01) reduced during the MUFA and PUFA n-6 periods but not during the PUFA n-3 diet with respect to the SFA diet. This effect was more pronounced in women than in men. In conclusion, the MUFA-enriched diet reduced SMC DNA synthesis and LDL levels and protected LDL from oxidation. Therefore, these combined effects suggest that an oleic acid-rich Mediterranean diet could be better than PUFA (n-6)- or PUFA (n-3)-rich diets in the prevention of atherosclerosis.

Cell Division↗
PubMed1996

Recurrent pneumococcal bacteremia. A warning of immunodeficiency.

BACKGROUND: Recurrent pneumococcal infections are known to occur occasionally in patients with profound immune defects. We performed a case-control analysis of recurrent pneumococcal bacteremias). PATIENTS AND METHODS: The 547 episodes of Streptococcus pneumoniae bacteremia detected from January 1, 1985, to December 31, 1994, were reviewed. We selected all cases with more than 1 episode separated by 30 days or more ("cases") and compared each of them with 2 controls (patients with single episodes of pneumococcal bacteremia). RESULTS: Fifteen patients (2.8%) had 31 episodes of pneumococcal bacteremia. Except for multiple myeloma (P < .02), the underlying disease was remarkably similar among patients with single and recurrent episodes of pneumococcal bacteremia. However, among patients positive for human immunodeficiency virus infection, those who had recurrences were at a more advanced stage of their disease than those who did not. The presence of an ultimately fatal underlying condition was more frequent in case patients (P < .001). Overall, 47% of the patients with recurrences died during their second episode of pneumococcal bacteremia. CONCLUSIONS: Our data suggest that recurrence is more than anecdotal in patients with bacteremic infections caused by S pneumoniae (2.8%). We believe that recurrence is a warning sign of immunodeficiency. Patients with multiple myeloma, human immunodeficiency virus infection, solid organ tumors, and chronic liver disease with bacteremic pneumococcal infections should be offered antipneumococcal vaccine and other potentially preventive measures, despite doubts about their efficacy. This is justified by the high mortality rate associated with recurrent episodes (47%).

AIDS-Related Opportunistic Infections↗
PubMed1996

Regulation of glucocorticosteroid receptor expression in rat hippocampal cell cultures by nerve growth factor.

Dispersed hippocampal cells cultured in serum-free conditions were used to study the effects of nerve growth factor (NGF) on the expression of type I (mineralocorticosteroid or MR) and type II (glucocorticosteroid or GR) corticosteroid receptors. Cells, plated at a density of 1.2 x 10(6) cells/ml in 60 mm Petri dishes, were mainly identified as neurons (90-95%) and maintained for at least 2 weeks. A 7-day treatment with 10-50 ng NGF/ml induced a concentration-dependent decrease of GR binding (40% decrease) compared to untreated cells. In contrast, MR density was unaffected by a 7-day treatment with 50 ng NGF/ml. Data are discussed as possible direct and/or indirect effects of NGF at the level of both neuronal and glial cells.

Animals↗
PubMed1996

A new method of antibiotyping yeasts for subspecies discrimination and distribution in human clinical specimens.

A study of the antibiotypes of 764 isolates of the genera Candida and Torulopsis from different clinical specimens is reported. The typing method was based on the susceptibility results obtained by the standardized and partially automated kit ATB-Fungus (API-bioMérieux), giving to each strain a code of six figures, according to these criteria: susceptibility to 5-fluorocytosine, amphotericin B, nystatin, miconazole, econazole, and ketoconazole. Candida albicans serotypes were determined by the Candida Check test (Iatron, Japan). Twenty-six antibiotypes were found in C. albicans (482 isolates), 21 types in serotype A, and 15 in serotype B strains. Candida parapsilosis (115 isolates) was divided into 11 antibiotypes, Torulopsis glabrata (53 isolates) into five, Candida guilliermondii (36 isolates) into 10 and Candida tropicalis (31 isolates) into eight. Depending on the sample origin, 000000 (susceptibility to all the antifungals tested) was the predominant C. albicans antibiotype (92.9% of blood isolates, 41.2% of vaginal isolates, 33.3% of respiratory isolates, isolates, 31.01% or oral and digestive tract isolates, and 25.0% of nail and skin isolates). No predominant antibiotypes were found in strains from respiratory tract, skin ad nails. A reproducibility close to 99% was found with the test. Simplicity and standardization could make this method useful for typing Candida and Torulopsis isolates.

Antibodies, Fungal↗
PubMed1996

Emergence of resistance to beta-lactam agents in enterobacteriaceae species with group I beta-lactamases in Spain.

The contribution of induction and stable derepression of chromosomal group I beta-lactamases to beta-lactam antibiotics resistance was studied in clinical isolates of Enterobacteriaceae, collected from patients treated with these antibiotics. Multiple isolates of the same species from the same patient were characterized by different typing methods. Sonicated extracts of cells were assayed for chromosomal and plasmid-mediated beta-lactamases by isoelectric focusing and cloxacillin inhibition studies. The specific beta-lactamase activity, basal and induced with cefoxitin, was determined to differentiate strains with inducible or derepressed production of the enzyme. Induction of beta-lactamases was performed in each strain against the beta-lactams used in the therapy of each patient. Older penicillins resulted in a moderate to strong increase in beta-lactamase activity, whereas the results obtained with first-generation cephalosporins were species dependent. Expanded-spectrum cephalosporins were weak inducers of beta-lactamases. Indeed, the use of cefotaxime for treatment preceded the appearance of strains that produced chromosomal group I beta-lactamases constitutively. These strains showed a remarkable reduction in sensitivity to ureidopenicillins, carboxipenicillins, expanded-spectrum cephalosporins, and monobactams, but not to carbapenems.

Anti-Bacterial Agents↗
PubMed1996

Evidence for modulation of dopamine-neuronal function by tachykinin NK3 receptor stimulation in gerbil mesencephalic cell cultures.

Primary cultures of gerbil mesencephalon were used for studying the modulation exerted by tachykinin NK(3) receptor activation on the activity of dopamine (DA) neurons. Dopamine neurons were identified by their ability to take up [(3)H]DA in a nomifensine-dependent manner. Moreover, tyrosine hydroxylase immunohistochemistry revealed that these neurons accounted for 5-7% of the total cell population. The NK(3) receptor agonists, senktide (EC(50) = 0.58 nM) and [MePhe(7)]neurokinin B (EC(50) = 3 nM), increased spontaneous [(3)H]DA release in a concentration-dependent manner. In contrast, tested at a supramaximal concentration (IC(50) = 0.89 nM), neither septide nor substance P were found to affect [(3)H]DA release. The senktide-evoked [(3)H]DA release was not observed when extracellular Ca(2+) was chelated, but was unaffected by nomifensine. This indicates that this increase in [(3)H]DA outflow resulted more from an exocytotic process than from reversal of carrier-mediated DA uptake. Moreover, the senktide effect was unaffected by the Na+ channel blocker tetrodotoxin, a result suggesting a direct action of senktide on DA neurons. The non-peptide NK(3) receptor antagonist, SR 142801, shifted or blocked (IC(50) = 0.89 nM) the senktide-evoked [(3)H]DA release, while its (-)-antipode, SR 142806, was 80-fold less potent, in agreement with binding data. Selective antagonists for Nk1 (SR 140333) or Nk2 (SR 48968) receptors failed to reduce the senktide effect. Light scanning microscopic analysis of mesencephalic cells loaded with the Ca(2+) sensitive dye, fluo-3, showed that senktide induced a rise in cytosolic Ca(2+) in 8-10% of the cell population. The senktide-induced elevation in intracellular Ca(2+) was rapid in onset and transient (at 10-8 M) or more sustained with no further increase in fluorescence intensity (at 10(-7) M). The proportion of senktide-responsive cells was not significantly modified when extracellular Ca(2+) was chelated, but was reduced by 87% in the presence of SR 142801 and by 75% in cultures that were pre-treated with the DA neurotoxin 1-methyl-4-phenylpyridinium. The present study shows that enhancement of spontaneous [(3)H]DA release and intracellular Ca(2+) mobilization may be observed after NK(3) receptor stimulation and that both biochemical events are likely to occur in DA neurons.

Animals↗
PubMed1996

Effect of dietary fat saturation on LDL oxidation and monocyte adhesion to human endothelial cells in vitro.

Forty-two healthy men and women were subjected to four consecutive dietary periods differing in the fat content of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (n-6) [PUFA(n-6)] and (n-3) [PUFA(n-3)]. Plasma lipids, vitamin E, and in vitro LDL oxidation were examined during each period. Adhesion of human monocytes to cultured human endothelial cells was used as a functional test to identify differences in the biological properties of LDL from each dietary period. Consumption of an SFA-rich diet resulted in higher LDL cholesterol (4.06 +/- 0.85 mmol/L, P < .05) than did consumption of MUFA- (3.59 +/- 0.75 mmol/L), PUFA(n-6)- (3.44 +/- 0.77 mmol/L), or PUFA(n-3)- (3.31 +/- 0.8 mmol/L) rich diets. HDL cholesterol was lower during both PUFA-rich diets (1.24 +/- 0.28 and 1.27 +/- 0.28 mmol/L for n-6 and n-3, respectively) than during the SFA-(1.32 +/- 0.36 mmol/L) and MUFA- (1.32 +/- 0.34 mmol/L) rich diets. LDL resistance to copper-induced oxidation, expressed as lag time, was highest during the MUFA-rich diet (55.1 +/- 7.3 minutes) and lowest during the PUFA(n-3)- (45.3 +/- 7 minutes) and SFA- (45.3 +/- 6.4 minutes) rich diets. LDL induction of monocyte adhesion to endothelial cells was lower during the MUFA-rich diet than the other periods. The highest monocyte adhesion was obtained during the PUFA(n-3) and SFA dietary periods. In conclusion, an MUFA-rich diet benefits plasma lipid levels compared with an SFA-rich diet. Furthermore, this diet results in an increased resistance of LDL to oxidation and a lower rate of monocyte adhesion to endothelial cells than the other dietary fats examined.

Adult↗
PubMed1996

Effect of conditions in obtaining blood samples for ECP testing in children.

Eosinophil Cationic Protein (ECP) is a basic protein found in eosinophil granules. This cell and its mediators are currently considered to be potential indicators of the severity of inflammation in the organism. ECP concentration can be reliably tested using several RIA or ELISA methods. It is well known that the conditions of sample obtention can affect the ECP values in blood. The aim of this study is to establish which parameters affect ECP testing during regular blood sample collection and how they affect it. Blood samples taken for the routine study of five children attended in our department were analysed: four were asthmatic and one child had atopic dermatitis. In the results we observed that ECP was not detected in the blood samples taken with EDTA tripotassium. In both the plasma samples taken with heparin as well as with serum, more ECP was released at a higher temperature. In the release of ECP obtained by coagulation, samples at 37 degrees showed values of between 4 and 20 higher than those obtained for an hour at 0 degrees. There is a considerable variability in the testing of ECP depending on the blood test extraction conditions, the range is bigger in the samples with eosinophils. These results imply the need to define a stricter protocol for obtaining samples than that suggested at present.

Adolescent↗
PubMed1995

Increased levels of statin, a marker of cell cycle arrest, in response to hippocampal neuronal injury.

Injured neurons in the CNS are known to synthesize high levels of proliferation related oncogene products and heat shock proteins without dividing. Statin is a cell cycle regulated nuclear phosphoprotein, selectively associated with the non-proliferative state in a wide variety of cell types. In the present study, neuronal statin was examined following lethal or sublethal neuronal injuries in the hippocampus of Alzheimer's disease patients, in rats receiving kainate lesions to the dorsal hippocampus and in entorhinal cortex lesioned rats. Immunolabelling of nuclear statin showed that statin immunoreactivity increased preferentially in CA1 pyramidal neurons of the hippocampus in Alzheimer's disease. In kainate lesioned rats, statin immunoreactivity was markedly induced in the CA3 hippocampal region in association with neuronal loss. Entorhinal cortex lesioned rats showed a transient induction of statin between 2 and 6 days post lesion in CA1 neurons. However, cell counts in entorhinal cortex lesioned rats remained unaltered in the CA1 and granule cell layers during the entire 30 day time course, indicating that increased statin levels are not secondary to neuronal degeneration and are not necessarily accompanied by irreversible neuronal death. It is concluded that, in addition to proliferation related gene products, neuronal injury induces an increase in levels of statin, a nuclear marker of cell cycle arrest. Furthermore, statin may be a potentially useful marker of injurious neuronal stress, even under conditions that do not necessarily lead to irreversible cell death.

Alzheimer Disease↗
PubMed1995

Single-word auditory stimulation and regional cerebral blood flow as studied by SPECT.

Single photon emission computed tomography (SPECT) examined changes in regional cerebral blood flow (rCBF) induced by passive auditory single-word stimulation. A split-dose SPECT technique was used between resting and activated states, in which a smaller amount of ligand (99m technetium hexamethyl propyleneamine oxide, HMPAO) was given with the first scan, accompanied by a prolonged scan time. A larger amount of ligand was given with the second scan, accompanied by a shorter scan time. This split-dose SPECT technique has met with previous success for other activation tasks. The brain regions of interest (ROIs) in this study were selected from ROIs previously found to be activated by passive auditory single-word stimulation and not by non-word stimuli in positron emission tomography (PET) rCBF studies. This study thus tested the sensitivity of SPECT with HMPAO to detect brain activation with a stimulus previously demonstrated to elicit changes in rCBF with PET. However, no significant difference was detected between resting and activated states in this study. Thus, SPECT was not as sensitive as PET in this activation task. Since SPECT is a less costly and more widely available modality to study brain activation than PET, it is important to delineate its potential capacities to maximize the efficiency of future research in this field.

Adult↗
PubMed1995

A modified method for the indirect quantitative analysis of phytate in foodstuffs.

A simple, precise, and reproducible method to quantitatively assess total phytate content in foodstuffs has been developed. After HCl extraction, samples were run through an anion-exchange column and total phytate content of the eluates was spectrophotometrically measured with the modified Wade reagent. The main changes introduced in our procedure refer to pH adjustment in the extraction, dilution, and quantitation steps (pH 0.60, 6.00, and 3.00, respectively). Furthermore, the minimal extraction time for legumes (2 h) was determined. In addition, the effect of protein content on phytate determination was tested. Phytate content directly measured in crude extracts omitting anion-exchange chromatographic purification was significantly lower (P < 0.01) than values obtained using column separation, thus demonstrating that reliable phytate assessment in foodstuffs demands the utilization of anion-exchange chromatography.

Anions↗
PubMed1995

Ovarian hormones regulate alpha 1- and beta-adrenoceptor interactions in female rat pinealocytes.

We have examined the effects of alpha 1- and beta-receptor activation on cyclic AMP (cAMP) accumulation in cultured pinealocytes from female ovariectomized rats, and from intact rats at proestrus treated with the antiestrogen Tamoxifen, the antiprogestagen RU486, or with both. Isoproterenol (a beta-agonist) significantly increased cAMP levels in pinealocytes from intact and ovariectomized rats. This response was considerably enhanced in pinealocytes from rats treated with RU486 or Tamoxifen alone, but not with both. Moreover, incubation of pinealocytes with isoproterenol together with phenylephrine (an alpha 1-agonist) produced a synergistic effect in animals that had been ovariectomized, or that had received RU486, either alone or in combination with Tamoxifen. These results suggest that, in female rats, ovarian steroids may regulate the interactions between alpha 1- and beta-adrenergic receptors, and thus modulate pineal melatonin synthesis during the oestrous cycle through these mechanisms.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1995

Biochemical and pharmacological characterisation of SR141716A, the first potent and selective brain cannabinoid receptor antagonist.

SR141716A is a selective, potent and orally active antagonist of the brain cannabinoid receptor with a long duration of action. This compound shows high affinity for the central cannabinoid receptor (Ki = 2 nM), displays low affinity for the peripheral cannabinoid receptor (Ki > 1000 nM). In vitro, SR141716A antagonizes the inhibitory effects of cannabinoid receptor agonists on both mouse vas deferens contractions and dopamine-stimulated adenylyl cyclase activities in rat brain membranes. After oral administration SR141716A totally inhibited the ex vivo [3H]-CP55,940 binding to cerebral membranes with a ED50 value of 3.5 mg/kg. Furthermore SR141716A antagonizes the classical pharmacological responses elicited by cannabinoid receptor agonists. In addition, SR141716A reverses the inhibitory effect of WIN55212-2 on isoniazid-induced elevation of cGMP in rat cerebellum. This compound will provide a powerful tool for studying the in vivo functions of the anandamide/cannabinoid system.

Animals↗
PubMed1995

Five-year survey of cefotaxime resistance in Spain.

During 1991-1995 a Spain collaborative study group surveyed the resistance to cefotaxime both in community as well as in hospital isolates of bacteria. The isolates tested during the study period of 5 years were 813, 875, 3631, 3184, and 3050 strains, respectively. Antimicrobial activity of cefotaxime was assayed by broth or agar microdilution, in accordance with criteria of the National Committee of Clinical Laboratory Standards (NCCLS). Cefotaxime resistance included 2.5% of all isolates: 2.6% Enterobacteriaceae, 1.7% Streptococcus pneumoniae, 0.5% Haemophilus influenzae, 0.0% Haemophilus spp., and 0.0% Moraxella catarrhalis. The overall incidence of resistance to cefotaxime decreased fro member of Enterobacteriaceae from 3.6% in 1991 to 2.5% in 1995. The incidence of resistance varied with the species and was highest in Enterobacter and in Citrobacter freundii.

Bacterial Infections↗