PubMed Health⌕ Search

Biomedical subjects

E Ballesteros

Publications and source records attributed to E Ballesteros.

At least 19 recordsLinked to original sources
PubMed2006

Simultaneous multidetermination of residues of pesticides and polycyclic aromatic hydrocarbons in olive and olive-pomace oils by gas chromatography/tandem mass spectrometry.

A multiresidue method for determining major pesticides and polycyclic aromatic hydrocarbons (PAHs) in olive oils in a single injection by use of gas chromatography/tandem mass spectrometry (GC-MS/MS) is proposed. Samples are previously extracted with an acetonitrile/n-hexane mixture and cleaned up by gel permeation chromatography. Electron ionization and chemical ionization allow pesticides and PAHs to be determined in a single analysis. The precision obtained was quite satisfactory (relative standard deviations ranged from 3 to 7.8%), and so were recoveries (84-110%). The linear relation was observed from 1 to 500 microg/kg for pesticides and 0.3 to 200 microg/kg for PAHs; also, the determination coefficient, R(2), was better than 0.995 in all instances. The proposed method was applied to the routine analysis of PAH and pesticide residues in virgin and refined olive oil and olive-pomace oil samples.

Chromatography, Gel↗
PubMed2004

Continuous solid-phase extraction and gas chromatographic determination of organophosphorus pesticides in natural and drinking waters.

A simple, rapid continuous-flow solid-phase extraction method with gas chromatographic detection for the determination of organophosphorus pesticides is proposed. The continuous system consists of an adsorbent column where pesticides are preconcentrated and subsequently eluted with ethyl acetate. Various sorbent materials were assayed of which RP-C18 was found to provide the best results, with a sorption efficiency close to 100%. A comparative study of the determination of pesticides in aqueous samples was conducted using gas chromatography with nitrogen-phosphorus (NPD) and flame ionization (FID) detection. The detection limits of the method for 10 ml of sample were between 50-130 ng/l and 4.5-1 1.7 microg/l with NPD and FID detection, respectively. The method was used to determine organophosphorus pesticides in river, pond, well and tap waters, all with good precision (2.9-4.3%) and recoveries ranging from 93.8 to 104.5%.

Chromatography, Gas↗
PubMed2003

Extreme lymphoplasmacytosis and hepatic failure associated with sulfasalazine hypersensitivity reaction and a concurrent EBV infection--case report and review of the literature.

We present an unusual case of a patient with extreme lymphoplasmacytosis and hepatic failure in association with a reaction to sulfasalazine and a concurrent Epstein-Barr virus (EBV) infection. Sulfa drugs can cause a wide range of allergic and hypersensitivity reactions and occasionally can lead to a fulminant illness. In the case under discussion the patient had hepatotoxicity, skin rash, fever, and peripheral blood atypical lymphocytosis. Initial impressions suggested the possibility of a malignant lymphoproliferative disorder. Flow cytometry of peripheral blood and a bone marrow biopsy provided clear evidence for a reactive, polyclonal process as opposed to a malignant disorder. Cessation of the offending drug and administration of steroids led to dramatic improvement. This case illustrates that drug hypersensitivity reactions can be manifested by an extreme lymphocytoid leukemoid reaction.

Adult↗
PubMed2003

Both duration and degree of hypercalcemia influence the reduced parathyroid hormone response to hypocalcemia after hypercalcemia.

The stimulation of parathyroid hormone (PTH) secretion by hypocalcemia is reduced when hypocalcemia is preceded by hypercalcemia. The present study investigates whether the duration and degree of hypercalcemia influence the reduced PTH response to hypocalcemia after hypercalcemia. In addition, the implication of the arachidonic acid (AA) signaling pathway in this effect is evaluated. The PTH response to hypocalcemia has been studied in a control group and in four groups of rabbits subjected to hypercalcemia for different periods of time (between 30 and 120 min) and at two levels of hypercalcemia (1 x 9 and 2 x 1 mM). AA levels have been measured in parathyroid glands from rabbits subjected to hyper- and hypocalcemia. When compared with controls, rabbits that had been hypercalcemic (2 x 1 mM) for 2 h showed a markedly attenuated PTH response to hypocalcemia (50% of normal PTHmax), rabbits that had been in hypercalcemia (2 x 1 mM) for 75 min had an intermediate PTH response to hypocalcemia (70% of normal PTHmax) and rabbits that had been subjected to either 30 min hypercalcemia of 2 x 1 mM or 120 min hypercalcemia of 1 x 9 mM had a normal PTH response to hypocalcemia. AA levels increased in hypercalcemia and decreased in hypocalcemia; however, no differences were observed at either calcium level in short-time (30 min) versus long-time (120 min) hypercalcemia. In conclusion, the attenuated PTH response to hypocalcemia after hypercalcemia is dependent on both the period of time that the parathyroid glands have been exposed to hypercalcemia and the degree of hypercalcemia. In addition, this reduced PTH response does not seem to be related to changes in the AA signaling pathway.

Animals↗
PubMed2001

The photosynthetic capacity of the seagrass Posidonia oceanica: influence of nitrogen and light.

Photosynthetic capacity of the seagrass Posidonia oceanica was determined in two contrasting nutrient zones along a bathymetric gradient. Photosynthetic capacity was two times higher in the relatively eutrophic zone compared to the highly oligotrophic zone. The same trend was observed in the chlorophyll a+b and tissue nitrogen content. Photosynthetic capacity and chlorophyll a+b decreased with irradiance in the oligotrophic zone while increased in the eutrophic zone. Tissue nitrogen content followed the same trend in the oligotrophic zone and did not present any trend in the eutrophic zone. Overall, this study has shown the importance of large scale sampling when assessing metabolic parameters such as photosynthetic capacity where large differences have been observed associated to the nutrient regime. According to our results, in oligotrophic zones nitrogen seems to govern photosynthetic capacity and there is a coherent pattern between nitrogen content, pigments and photosynthetic capacities. In eutrophic zones, light is the dominant regulator and there is a coherent pattern between light and photosynthetic capacities.

Journal Article↗
PubMed2001

Pharmacokinetic behaviour of phenylglyoxal bis(guanylhydrazone) (PGBG) after intravenous administration in rabbits.

Phenylglyoxal bis(guanylhydrazone) (PGBG) is a synthesized analogue of methylglyoxal bis(guanylhydrazone) (MGBG), which has demonstrated anti-parasitic activity in rabbits. The pharmacokinetic behaviour of PGBG after intravenous administration (10 mg/kg bodyweight) was studied in five rabbits. Plasma concentrations of PGBG were measured by high-performance liquid chromatography. Plasma PGBG concentrations decreased rapidly and were not detectable beyond 90 min after treatment. The mean [+/- standard deviation (SD)] volume of distribution at steady state (Vdss) was 2.19 +/- 0.47 l/kg and the mean plasma clearance value (Cl) was 29.99 +/- 3.98 ml/min kg. This drug is rapidly eliminated from the body in rabbits, having a short elimination half-life (0.93 h) and mean residence time (1.21 h).

Animals↗
PubMed2000

Analytical potential of fullerene as adsorbent for organic and organometallic compounds from aqueous solutions.

In this work, the analytical potential of C60 fullerene as a sorbent for organic and organometallic compounds from aqueous solutions was studied for the first time. Fullerene adsorbs many types of organic substances (e.g., N-methylcarbamates, phenols, polycyclic aromatic hydrocarbons, amines) with efficiencies that depend on the nature of the compound concerned and never exceed 60%. Conventional sorbents such as XAD-2 or polyurethane foam are more efficient than C60 for this purpose. Organometallic compounds (viz. metalocenes and organoleads) are quantitatively adsorbed on C60 via the formation of neutral complexes or chelates; the adsorption constant is dramatically increased by the use of classical reagents such as pyrrolidinedithiocarbamate or diethyldithiocarbamate. A complementary comparative study on the adsorption of organometallic complexes on RP-C18 and silica gel 100, among others, showed C60 to be superior as sorbent. All experiments in this work were carried out by using continuous flow configurations and gas chromatography-atomic absorption spectrometry techniques.

Adsorption↗
PubMed2000

Cleaning of liquid radioactive wastes using natural zeolites.

Natural zeolite, clinoptilolite, was used to eliminate liquid radioactive wastes (LRW) 137Cs and 90Sr. The influence of several factors (pH of solution, grain size of the zeolite, etc.) on the process effectivity was studied. It was shown that clinoptilolite is an effective filter of the nuclides above.

Journal Article↗
PubMed1998

Involvement of the L-arginine/nitric oxide neural pathway in non-adrenergic, non-cholinergic relaxation of the bovine oesophageal groove.

1. The distribution and localization of nitric oxide synthase (NOS) immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity in the bovine oesophageal groove were investigated by immnunohistochemical and histochemical staining techniques. Functional in vitro studies were performed to correlate the presence of NOS-immunoreactivity (IR) and NADPH-d staining with smooth muscle relaxations involving the L-arginine/nitric oxide neural pathway in the bovine oesophageal groove activity. 2. NOS-IR and NADPH-d were expressed in nerve cell bodies of the myenteric, submucosal and intramuscular ganglia, and in nerve fibres distributed around blood vessels and throughout the different muscular layers of the bovine oesophageal groove. 3. In oesophageal groove strips treated with guanethidine (10(-5) M) and atropine (10(-7) M) to block noradrenergic neurotransmission and muscarinic receptors, respectively, electrical field stimulation (EFS, 0.5-32 Hz, 1 ms duration, 20-s trains) induced relaxations which were practically abolished by tetrodotoxin (TTX, 10(-6) M). 4. Incubation with an inhibitor of nitric oxide synthesis, NG-nitro-L-arginine (L-NOARG, 3 x 10(-5) M), significantly inhibited relaxations induced by EFS. This inhibition was partially reversed by L-arginine (L-arg, 5 x 10(-3) M). D-NOARG (3 x 10(-5) M) had no effect on EFS-induced relaxations. 5. NO added as an acidified solution of NaNO2 (10(-6) - 10(-3) M) and S-nitroso-L-cysteine (10(-7) - 10(-4) M) caused concentration-dependent relaxations of the bovine oesophageal groove. These relaxations were unaffected by L-NOARG (3 x 10(-5) M). 6. The presence of NO-synthesizing enzyme in nerves and ganglia, and the pharmacological evidence for NO-mediated smooth muscle relaxation suggested that the L-arg/NO neuronal pathway is involved in the inhibitory neurotransmission of the bovine oesophageal groove.

Animals↗
PubMed1998

CD5+ low-grade marginal zone B-cell lymphomas with localized presentation.

Marginal zone B-cell lymphomas (MZBCLs) are low-grade lymphomas that characteristically lack CD5 expression. However, rare cases of MZBCL have been described in which the lymphomatous B cells coexpress CD5 (CD5+ MZBCL). In 7 of 9 reported CD5+ MZBCLs, there was evidence of widespread disease. We report four additional cases of CD5+ MZBCL. Three cases were low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) involving the lungs, the conjunctiva (bilateral), and the uterus. The remaining case represented a monocytoid B-cell lymphoma involving a posterior cervical lymph node. Southern blot hybridization did not show rearrangements of bc11 or bc12 in the three cases analyzed. All four patients had localized disease and normal peripheral blood counts. Staging of bone marrow biopsies from three patients did not show evidence of bone marrow involvement. The remaining patient had bilateral conjunctival lesions that were present for 15 years without progression. These four additional cases of CD5+ MZBCL show that this group of low-grade B-cell lymphomas occasionally may exhibit an atypical phenotype. Furthermore, in this study, the CD5+ MZBCLs were clinically localized at presentation, in contrast to most other reported cases, which have had dissemination to bone marrow or peripheral blood.

Aged↗
PubMed1998

Plasma cell granuloma of the oral cavity: a report of two cases and review of the literature.

We report two rare cases of plasma cell granuloma arising in the extragingival oral cavity. These are tumorous proliferations composed predominantly of reactive plasma cells. Both patients presented with solitary mass lesions that were clinically suspicious for malignancy. One patient presented with a mass that grew slowly for 2 years and involved the lip; in the second patient, a mass developed in the buccal mucosa Histologically, both lesions were characterized by lobules of plasma cells separated by thick collagenous bands. A variable number of admixed lymphocytes and histiocytes was noted in both cases. In situ hybridization and immunostaining for kappa and lambda light chains revealed a polyclonal plasma cell population. In situ hybridization for Epstein-Barr virus failed to demonstrate evidence of viral expression in either case. Both patients are free of disease after 8-month and 12-month follow-ups. Although plasma cell granuloma in the oral cavity is rare, it is important to recognize this entity as a benign inflammatory lesion.

Adolescent↗
PubMed1997

Fine-needle aspiration diagnosis of enterogenous cyst of the orbit: a case report.

Enterogenous cyst is a benign lesion derived from misplaced endodermal epithelium. We report the aspiration cytology findings of an orbital cyst from a 32-year-old woman. The smears contain benign-appearing cuboidal glandular cells with focal mucinous features. Carcinoembryonic antigen level in the cyst fluid was markedly elevated. These findings are consistent with recurrence of the enterogenous cyst initially diagnosed 7 years earlier.

Adult↗
PubMed1997

Acetylcholinesterase histochemistry and functional characterization of the muscarinic receptor mediating the contraction of the bovine oesophageal groove.

1. By using acetylcholinesterase (AChE) histochemistry and in vitro isometric techniques, we have studied the presence and distribution of AChE-positive nerves, as well as the effects of muscarinic cholinoceptor agonists and selective antagonists, in the bovine oesophageal groove. 2. AChE-positive nerves and cells were distributed widely on the oesophageal groove floor. These fibres originated from adventitial ganglia containing bodies with high AChE activity and were shown grouped as large adventitial nerve bundles. 3. Both in the presence and absence of physostigmine, acetylcholine (ACh) induced concentration dependent contractions of bovine oesophageal groove strips. The rank order of the pD2 values for muscarinic agonists was: oxotremorine-M (7.37) = carbachol (7.14) > acetylcholine plus physostigmine (6.46) > bethanechol (5.42) > McN-A-343 (4.45) > acetylcholine (4.06). 4. Hexamethonium (10(-6)-10(-4) M), a nicotine receptor blocker, did not affect the carbachol concentration-response curve, which was significantly inhibited by the muscarinic antagonist, atropine (10(-9)-10(-8) M). 5. The preferential muscarinic antagonists pirenzepine (M1), 11-(2(diethyl-amino)methyl)-1- piperidinylacetyl)-5,-11-dihydro-6H-pyrido(2,3-b)-(1,4)-benzodiaze pine-6-one (AF-DX 116) and methoctramine (M2), 4-diphenyl-acetoxy-N-methyl-piperidine methiodide (4-DAMP) and p-fluorohexahydrosiladiphenidol (p-F-HHSiD) (M3) evoked rightwards displacements in a parallel manner of the carbachol control curve, and there was no decrease of the maximum response with the highest concentration of antagonist utilized. The muscarinic antagonist affinities, expressed in terms of pA2, values, were: atropine (9.51) = 4-DAMP (9.32) > p-F-HHSiD (7.78) > tropicamide (7.40) > pirenzepine (6.91) = AF-DX 116 (6.88) = methoctramine (6.71). This muscarinic antagonist profile suggests that an M3 receptor is involved in the carbachol induced contraction. 6. The present results suggest that a rich network of AChE- positive fibres is present in the oesophageal groove floor, where they form a nerve trunk and thinner branches accompanying blood vessels and sometimes around ganglia. The muscarinic cholinergic contraction of the bovine oesophageal groove seems to be mediated via activation of an M3 postsynaptic muscarinic receptor.

Acetylcholine↗
PubMed1997

In vitro cytotoxicity of guanylhydrazones (MGBG and PGBG) on cultured Chinese hamster ovary cells.

Guanylhydrazones, methylglyoxal bis(guanylhydrazone) (MGBG) and a new compound, phenylglyoxal bis(guanylhydrazone) (PGBG), interfering with polyamine biosynthesis have considerable potential for the use as antiparasitic and antitumor agents. The effect of these drugs on the cellular viability of Chinese hamster ovary cells was examined by in vitro neutral red assay. The time exposure and metabolic influence was studied. These compounds have a dose- and time-dependent cytotoxicity. The IC50 values were of 597.22 micrograms/ml and 1.77 micrograms/ml for MGBG after 3 and 24 h of incubation, respectively, and 380.50 micrograms/ml for PGBG after 24 h of incubation. The PGBG treatment during 3 h had no cytotoxic effect when the concentrations were lower than 3000 micrograms/ml. With the cytotoxicity assay used, we observed that the presence of S9 in cultured medium did not influence the cytotoxicity of these compounds.

Adenosylmethionine Decarboxylase↗
PubMed1996

Gas chromatographic determination of cholesterol and tocopherols in edible oils and fats with automatic removal of interfering triglycerides.

An automated gas chromatographic method for the simultaneous determination of cholesterol, alpha-tocopherol and alpha-tocopheryl acetate in edible oils and fats without derivatization is reported. Interferences from lipid material are avoided by using a continuous system to transesterify triglycerides with potassium methylate in methanol. The precision of the method is 1.9, 2.2 and 3.1% for cholesterol, alpha-tocopherol and alpha-tocopheryl acetate, respectively. The proposed methods was validated by analysing a standard reference material of coconut oil (SRM 1563-2) with good results. The method features a high throughput, minimal sample handling and analyte specificity (lipid material does not interfere).

Cholesterol↗
PubMed1996

Direct effect of phosphorus on PTH secretion from whole rat parathyroid glands in vitro.

Phosphorus retention is an important factor in the development of hyperparathyroidism secondary to renal failure. In vivo manipulation of phosphorus is associated with changes in serum calcium and calcitriol levels which in turn can modify parathyroid hormone synthesis and secretion. The present in vitro study evaluates whether high extracellular phosphorus has a direct effect on parathyroid hormone secretion. Fresh rat parathyroid glands were incubated in a media with phosphorus concentrations of 1, 2, 3, and 4 mM and subsequently exposed to calcium levels ranging from 0.4 to 1.35 mM. In 1.25 mM calcium, the parathyroid hormone secretion rate was similar in 1 and 2 mM phosphorus; however, a phosphorus concentration of 3 and 4 mM produced a 3- and 4-fold increase in the parathyroid hormone secretion, respectively, as compared with 1 mM phosphorus. While in 1 or 2 mM phosphorus an increase in calcium from 0.6 to 1.35 mM reduced parathyroid hormone secretion to 37%, in 4 mM phosphorus the same increase in calcium only inhibited parathyroid hormone secretion to 75%. Furthermore, the addition of arachidonic acid 20 microM, a substrate for inhibitory intracellular signal pathway, to the 4 mM phosphorus-1.35 mM calcium incubation media reduced the parathyroid hormone secretion to 34.5% (p < 0.05). In conclusion, our results indicate that in vitro, high phosphorus directly increases parathyroid hormone secretion.

Analysis of Variance↗
PubMed1995

Automatic gas chromatographic determination of the high-density-lipoprotein cholesterol and total cholesterol in serum.

A new analytical method that combines on-line precipitation-filtration, enzymatic hydrolysis, extraction and gas chromatography was developed for the determination of total cholesterol and high-density-lipoprotein cholesterol in human serum. Very-low-density lipoprotein, intermediate-density lipoprotein and low-density lipoprotein are precipitated with sodium phosphotungstate and magnesium chloride; then, the serum is continuously filtered and unprecipitated high-density-lipoprotein cholesterol is enzymatically hydrolyzed and finally determined as cholesterol by gas chromatography. Total cholesterol is also determined by direct introduction of the serum into the proposed system. The proposed method was validated by analyzing a lipid control serum with certified contents of high-density-lipoprotein cholesterol and total cholesterol. The results obtained were consistent with the certified contents.

Cholesterol↗