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Biomedical subjects

M Gallego

Publications and source records attributed to M Gallego.

At least 55 records · Page 3Linked to original sources
PubMed2000

Immunohistochemical study of the cyst of Besnoitia besnoiti.

The present study has been undertaken in order to provide information on the molecular structure of the cysts of Besnoitia besnoiti. To that end, immunohistochemical techniques have been used to investigate the expression of several enzymes and proteins implicated in the cellular membrane permeability of bradyzoites. Paraffin and frozen sections, which were obtained from subcutaneous tissue samples taken from naturally infected cattle (coming from northeast Spain), were treated with a panel of antibodies. These were specific for Na(+), K(+)-ATPase, alkaline phosphatase, calmodulin, S100 protein, heat shock proteins, hsp60, and hsp70. Positive-cysts for the said antibodies were found in 23.3% of the cows studied. Bradyzoites showed a positive immunoreaction in every positive cyst with respect to all these antibodies. In addition to the low percentage of positive animals, it is worth noting that positive and unstained cysts were observed in the same tissue section. These results suggest that bradyzoites may pass through both active and dormant metabolic phases.

Adenosine Triphosphatases↗
PubMed2000

Simplified method for the determination of chlorinated fungicides and insecticides in fruits by gas chromatography.

A fast, reliable method for the determination of more than twenty chlorinated fungicides and insecticides in a variety of fruit samples is presented. The pesticides are extracted from chopped samples with magnetic stirring, after adding 13 ml of acetone-phosphate buffer-brine solution (12:1, v/v) with 5 ml of n-hexane. The continuous module employed allows sequential decolourization of the organic phase, solvent changeover and solid-phase extraction for clean-up and preconcentration purposes. A 1-microl aliquot of the pesticides in ethyl acetate (eluent) is finally injected into the gas chromatograph for separation and identification. The method provides excellent clean-up despite the complexity of the matrices involved. Fruit samples (5-20 g) containing 0.1-1250 ng/g pesticides were analysed with a high precision (4-6%). After contamination of the fruit samples for 12 h, average recoveries >90% at fortification levels of 5-25 ng/g were obtained for most of the pesticides. Positive findings of these pesticides in fruits purchased at local markets were confirmed by GC-MS.

Chromatography, Gas↗
PubMed2000

Speciation of inorganic lead and ionic alkyllead compounds by GC/MS in prescreened rainwaters

A simple and novel screening method for lead compounds in environmental waters is proposed. The analytes, in an acetic medium, are sorbed on a C60 fullerene column as diethyldithiocarbamate complexes and subsequently eluted with isobutyl methyl ketone (IBMK), the lead being determined by flame atomic absorption spectrometry. The screening method acts as filter and indicates whether the target analytes are present above or below the detection limit of the method (0.5 ng/mL), giving no false positives. Positive samples were speciated by GC/MS, using a flow system similar to that of the screening method. Lead(II) and ionic di- and trialkyllead are derivatized with a Grignard reagent. Both methods use similar chemical and flow variables except for the eluent, IBMK in the screening method and n-hexane in the speciation method. The GC/MS speciation method is very sensitive; it exhibits a linear range of 0.02-5 ng/mL, and detection limits of 1-4 ng/L are achieved. Also, its repeatibility, as RSD, is less than 6%. The method was applied to the speciation of Pb2+ and di- and trialkyllead in positive prescreened rainwater samples from three different urban areas.

Journal Article↗
PubMed2000

Immunohistochemical study of S100-like protein in Eimeria brunetti and Eimeria acervulina.

We have investigated the expression of a calcium-binding protein, the S100 protein, in Eimeria brunetti and Eimeria acervulina stages. For this purpose, paraffin sections of distal ileum and bursa of Fabricius or duodenum from experimentally infected chickens were treated with anti-alpha-S100 (anti-alpha subunit of S100 protein) and anti-beta-S100 (anti-beta subunit of S100 protein) monoclonal antibodies and anti-S100 whole molecule polyclonal antibody. The avidin-biotin peroxidase method was used to demonstrate immunoreactivity. In the ileum, our results reveal a positive immunoreaction for the beta subunit and S100 whole molecule within the macrogametes of E. brunetti, whereas they were devoid of immunostaining after treatment of the paraffin sections with the anti-alpha-S100 antiserum. Schizonts and oocysts of E. brunetti and all the E. acervulina stages gave a negative reaction after treatment with any of the three antiserum used in the study. This result indicated that the S100 protein molecules within these stages were not recognized by the antibodies, suggesting that these molecules are different from those identified in macrogametes of E. brunetti. By contrast, in the epithelial cells, lining the lumen of the bursa of Fabricius, macrogametes of E. brunetti were stained by the three antibodies used. These results may indicate the existence of metabolic adaptations that enable the parasite to invade tissue sites different from those where the parasite usually develops.

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

Effects of diabetic cardiomyopathy on regional electrophysiologic characteristics of rat ventricle.

AIMS/HYPOTHESIS: To identify the possible causes of the lengthening of the action potential duration described in patients affected by diabetes mellitus. METHODS: We studied the effects of streptozotocin-induced diabetes on the current density of the repolarising potassium currents It(o), IK, Iss and IK1 in enzymatically isolated myocytes from three different regions of rat heart: total right ventricle, subepicardium at the apex of the left ventricle and subendocardium at the base of the left ventricle. RESULTS: No changes in IK1 were found due to diabetes, but there was a uniform decrease in It(o) (50%) and Iss (40%) current densities in the three regions. In contrast, IK diminished unevenly, with the greatest decrease in the subendocardium at the base of the left ventricle (48%), followed by the subepicardium at the apex of the left ventricle (32%) and right ventricle (10%). CONCLUSION/INTERPRETATION: These findings suggest the existence of regional differences in ion channel expression associated with diabetes. The decrease of these repolarising currents could account for the lengthening of action potential and the consequent change in the Q-T interval of the ECG observed in diabetic rats.

4-Aminopyridine↗
PubMed2000

Restoration of cardiac transient outward potassium current by norepinephrine in diabetic rats.

In cardiac ventricle, the density of the transient outward potassium current, Ito, is clearly related to sympathetic nervous system integrity. This sympathetic regulation of Ito expression may be greatly significant to the genesis of cardiac complications of several diseases such us diabetes mellitus. Autonomic neuropathy, including cardiac neuropathy, is a complication of chronic diabetes. The objective of the present study was to identify the possible role of cardiac sympathetic neuropathy in the reduction of Ito current density in diabetic ventricular myocardium. Thus, we employed the patch-clamp technique to test whether Ito can be restored in diabetic myocytes incubated with norepinephrine. We also measured, using HPLC, the catecholamine content of the stellate ganglion, which is responsible for cardiac sympathetic innervation, in normal and diabetic animals. The main result of the present study was to show that a 24-h incubation of diabetic cells with norepinephrine restores Ito density to control values. The restoration of Ito current density by norepinephrine suggests that the diabetes-induced reduction of Ito is at least partially attributable to a reduced trophic effect of norepinephrine on the expression of Ito.

Adrenergic alpha-Antagonists↗
PubMed2000

Continuous sorbent preconcentration for the electrothermal atomic absorption spectrometric determination of ultratrace amounts of cobalt in milled wheat fractions.

A method for the rapid determination of cobalt at ultratrace levels was applied in flour and flour byproducts (shorts and bran) obtained from various types of wheat that includes on-line preconcentration and electrothermal atomic absorption spectrometry is proposed. Solutions in 0.1 mol/L HNO(3) of milled wheat fractions subjected to wet ashing are preconcentrated in a straightforward flow-injection system by sorption on a RP-C(18) column following chelation. The eluent, ethanol, is carried by an air stream, and the chelate is eluted and collected in a 500 microL PTFE autosampler cup. The determination of cobalt features a precision (RSD) of 6% for a concentration of 0.2 ng/mL and a sensitivity (slope of the calibration graph) of 0.38 +/- 0.03 A s x ng/mL. The cobalt content in each type of wheat was found to be influenced by its geographical origin and texture. Also, it was found to depend on the amount of bran present in the milled wheat fraction. On the other hand, it is not significantly affected by the technological processes involved in wheat milling at a flour-producing factory.

Cobalt↗
PubMed2000

Fast urinary screening for paracetamol using on-line microwave assisted hydrolysis and spectrophotometric detection.

A fully automated urinary screening system for paracetamol and its metabolites is proposed. The method comprises on-line acid microwave assisted hydrolysis of the drug to p-aminophenol followed by reaction with o-cresol in alkaline medium. The indophenol blue dye formed can be continuously monitored at 620 nm. The detection limit achieved, 0.1 microgram ml-1, allows a high dilution of the samples, thus reducing potential interferences from the sample matrix (mainly protein degradation during urine hydrolysis). The proposed screening system also possesses an adequate selectivity, as the major interferent, epinephrine, is tolerated at concentrations higher than those that could be found in the positive urine samples. The reproducibility, expressed as relative standard deviation, was 3.0% and the sample frequency 20 h-1. The reliability of the method was established at five concentrations (between 0.5 and 4 times the detection limit). Finally, it was applied to the screening of several human urine samples. The results obtained were compared with those provided by batch acid hydrolysis, and were similar in all instances.

Acetaminophen↗
PubMed2000

Seminal plasma proteins revert the cold-shock damage on ram sperm membrane.

Ejaculated ram spermatozoa, freed from seminal plasma by a dextran/swim-up procedure and exposed to cold shock, were incubated with ram seminal plasma proteins and analyzed by fluorescence markers and scanning electron microscopy. Seminal plasma proteins bound to the sperm plasma membrane modified the functional characteristics of damaged spermatozoa, reproducing those of live cells. Scanning electron microscopy showed that the dramatic structural damage induced by cooling reverted after incubation with seminal plasma proteins. Assessment of membrane integrity by fluorescence markers also indicated a restoration of intact-membrane cells. This protein adsorption is a concentration-dependent process that induces cell surface restoration in relation to the amount of protein in the incubation medium. Fractionation of ram seminal plasma proteins by exclusion chromatography provided three fractions able to reverse the cold shock effect. Scanning electron microscopy also confirmed the high activity of one fraction, because approximately 50% of cold-shocked sperm plasma membrane surface was restored to its original appearance after incubation. Differences in composition between the three separated fractions mainly resulted from one major band of approximately 20 kDa, which must be responsible for recovering the sperm membrane permeability characteristic of a live cell.

Adsorption↗
PubMed2000

Proliferating trichilemmal cyst with focal invasion: report of a case and a review of the literature.

Proliferating trichilemmal cyst (PTC) is a rare but morphologically distinctive tumor that usually occurs in the scalp of elderly women. Furthermore, only 30 well-documented examples of so-called malignant PTC have been reported. Alternatively, some authors have recently proposed that PTC is squamous cell carcinoma. We describe a case of PTC with focal invasion that was indistinguishable from squamous cell carcinoma in areas, and we review the literature. This debate should be considered in PTCs to provide adequate treatment (wide local excision) and follow-up (long term), particularly in large and long-standing lesions.

Aged↗
PubMed2000

Effects of amphetamine on calcium and potassium currents in rat heart.

We used the patch-clamp technique to study the effects of amphetamine on the membrane currents responsible for rat cardiac action-potential duration. Amphetamine has no effect on the slow inward Ca2+ current (I(Ca)-L), the inwardly rectifying K+ current (I(K1) and the outward K+ delayed rectifier (I(K)) and sustained (I(SS)) currents. Amphetamine blocks the transient outward K+ current (I(to)) both in the open and in the rested state. The transient outward K+ current is largely responsible for action-potential repolarization and for the regional differences in action-potential duration in rat ventricle. Therefore, the reduction of the transient outward K+ current (I(to)) caused by amphetamine may facilitate the appearance of ventricular tachycardia and fibrillation, a reported cause of death in amphetamine users.

Amphetamine↗
PubMed2000

Short-term modulation of lipogenesis by macronutrients in rainbow trout (Oncorhynchus mykiss) hepatocytes.

Rainbow trout (Oncorhynchus mykiss) hepatocytes were cultured under simulated conditions of varying nutritional status to explore the short-term modulation by dietary substrates of the main lipogenic enzymes: glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACoAC) and fatty acid synthetase (FAS). Primary cultures were individually exposed to varying amounts of glucose, hydrolysed casein and long-chain polyunsaturated fatty acids (PUFA) for 12 h. A second set of experiments was designed to evaluate the effects of mixing different relative amounts of these macronutrients in the culture medium. Glucose concentrations of up to 20-25 mm showed a stimulatory effect on G6PD, ME, ACL and ACoAC activity while an earlier inhibitory effect on FAS was observed at 10-20 mm glucose The use of hydrolysed casein as a nutritional source of amino acids inhibited the activity of FAS and ME and stimulated G6PD, ACoAC and ACL activity Low levels of linolenic acid exerted a stimulatory effect on all the lipogenic enzymes assayed with the exception of FAS, and increased amounts showed some inhibition of lipogenic activities Eicosapentaenoic acid and docosahexaenoic acid showed a similar effect, although the former strongly inhibited FAS activity while the latter showed greater potential to inhibit ACoAC and G6PD. A complete change in the relative levels of glucose, hydrolysed casein and PUFA in turn led to changes in the enzyme activity patterns observed. The present study shows the feasibility of exploring the direct regulation of lipogenesis in isolated fish cells by varying the relative amounts of main macronutrients, mimicking in vivo dietary conditions. It is felt that such an approach may serve to investigate the macronutrient regulation of other metabolic pathways.

Animals↗
PubMed2000

[Regenerative potential in the organ of Corti after otic intoxication].

The auditory sensory cells are sensitive to a variety of influences such as noise, ototoxic drugs and aging. In the cochlea of mammals, the destroyed sensory cells are not replaced by new sensory cells. That leads to cochlear deafness, a frequent disease in human. Unfortunately, such auditory impairment is out of reach of treatment. The development of new therapeutic strategies in this field requires a precise knowledge of the mechanisms involved in auditory sensory cells disappearance and in organ of Corti's degeneration. The aim of our study was to characterize cellular and molecular changes in the cochlea of rats which had been intoxicated with the ototoxic antibiotic amikacin. The animals were sacrificed at different survival times during and after the antibiotic treatment and their cochleas were investigated using transmission and scanning electron microscopy and using confocal microscopy after tissue labellings with different fluorescent probes. The results revealed the existence of three periods. The first one corresponds to the disappearance of the sensory cells which die by apoptosis. During the second period, the organ of Corti undergoes a scarring process; concomitantly, a contingent of nonsensory supporting cells attempts to transdifferentiate directly into sensory cells. This process however fails, and the supporting cells never reach the status of hair cells. A general process of dedifferentiation of all the epithelial cells of the organ of Corti followed by a massive apoptosis of numerous epithelial cells and of most ganglion cells occurs during the third period. After that, the organ of Corti is definitely reduced to a simple monolayered epithelium. On the basis of these data, experimental strategies aimed i) to protect the sensory cells against apoptosis and ii) to promote sensory cell regeneration are now under study. They might have important implications in human therapy.

Amikacin↗
PubMed1999

Semiautomatic method for the screening and determination of 23 organochlorine pesticides in horticultural samples by gas chromatography with electron-capture detection.

A rapid, simple, efficient device for the extraction-preconcentration of 23 organochlorine pesticides currently applied to vegetables is proposed. Pesticide residues are extracted from chopped samples by using a mixture of distilled water and light petroleum (1:1, v/v). After phase separation, an aliquot of the organic layer is continuously evaporated to dryness under a N2 stream as it is dropped into a glass tube containing distilled water. The aqueous phase, containing the analytes, is then passed through a miniaturized RP-C18 column for preconcentration, clean-up and subsequent elution with 150 microliters of ethyl acetate. A volume of 1 microliter of the extract containing pesticides is injected into the gas chromatograph, fitted with an electron-capture detector, for their selective determination. Limits of detection vary between 0.04 and 10 ng/ml, with linear ranges from 0.2 to 500 ng/ml; the average relative standard deviation at the low nanogram-per-millilitre level is 5.3%. The potential of the proposed method was realized by applying it to the screening/determination of organochlorine pesticides in horticultural commodities.

Automation↗
PubMed1999

Gas chromatographic flow method for the preconcentration and simultaneous determination of antioxidant and preservative additives in fatty foods.

A partially automated gas chromatographic method for the simultaneous determination of antioxidants (tert.-butyl-4-hydroxyanisole, 2,6-di-tert.-butyl-p-hydroxytoluene, tert.-butylhydroquinone, alpha-tocopherol and alpha-tocopheryl acetate) and preservatives (sorbic acid, benzoic acid and their esters) in fatty foods without derivatization is reported. About 95% of triglycerides from lipid material are avoided by manually extracting the samples with a mixture of solvents and the remaining by using a continuous solid-phase extraction system. By using aqueous sample solutions (in 0.1 M HNO3), XAD-2 sorbent and selective elution with 200 microliters of 2-propanol, only ca. 0.03% of total triglycerides present in the original sample remains in the final extract. Manual injection of the extract into a GC-flame ionization detection allows the additives to be determine at concentrations in the range 0.5-100 micrograms/ml with a high precision (ca. 3%). Mass spectrometry in the conventional electron impact mode, in conjunction with library search, permits the unequivocal identification of all the additives. Margarine, oil, cheese, pâté and sauce samples were analysed in this way, all with good results.

Antioxidants↗
PubMed1999

Discrimination of structural isomers of chlorinated phenols in waters using gas chromatography-mass spectrometry in the negative chemical ionization mode.

The analysis and identification of structural isomers of mono-, di- and trichlorophenols is reported. The fragmentation of the phenols was examined by GC-MS in both electron impact (EI) and negative chemical ionization (NCI) modes, using methane as reagent gas. The ability of NCI to discriminate these isomeric compounds from differences in relative intensities for selected peaks is demonstrated. 3- and 4-chlorophenols have similar retention times; however, they can still be discriminated because their negative mass spectra and rather different. In dichlorophenols, the presence of one chlorine atom in the ortho position decreases their retention time and the relative intensity of the fragment ion at m/z 140. The NCI mass spectra for trichlorophenols are different from the rest, particularly for the m/z value corresponding to the chlorine atom. Tetra- and pentachlorophenols were also studied and sequential losses of Cl observed. An automatic solid-phase extraction system can optionally be used to preconcentrate chlorophenols in waters prior to determination at legally established toxic levels.

Gas Chromatography-Mass Spectrometry↗