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A Prieto

Publications and source records attributed to A Prieto.

At least 37 records · Page 2Linked to original sources
PubMed2001

Determination of fipronil by solid-phase microextraction and gas chromatography-mass spectrometry.

A method for the determination of trace amounts of the insecticide fipronil was developed using solid-phase microextraction-gas chromatography-mass spectrometry and selected ion monitoring. Fipronil was extracted with a fused-silica fiber coated with 85 microm polyacrylate. The effects of pH, ionic strength, sample volume, extraction and desorption times as well as the extraction temperature were studied. Lindane was used as an internal standard. The linear concentration range of application was 0.3-100 ng ml(-1) of fipronil, with a relative standard deviation of 9.5% (for a level of 50 ng ml(-1)) and a detection limit of 0.08 ng ml(-1). The method was applied to check the eventual existence of fipronil above this limit in water and soil samples from Granada (Spain) as well as in human urine samples. The method validation was completed with spiked matrix samples. The method can be applied as a monitoring tool for water, soil and urine, in the investigation of environmental and occupational exposure to fipronil.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Epidermoid cyst of the testis: a case report.

Epidermoid cyst of the testis is an uncommon benign tumour, with an overall incidence of 1-2% of all resected testicular masses. When imaging findings suggest that an intratesticular mass is likely to be an epidermoid cyst, conservative management (enucleation with testicular preservation) can be performed rather than orchidectomy. This case report records an epidermoid cyst in a 12-year-old boy in whom the US findings allowed testis-sparing surgery instead of orchidectomy.

Child↗
PubMed2001

Differential-pulse adsorptive stripping voltammetric determination of the antibacterial lomefloxacin.

A differential-pulse adsorptive stripping voltammetric method for the determination of trace amounts of the antibacterial lomefloxacin is proposed. By using an accumulation potential of -0.30 V and a 2 min accumulation time, the linear concentration range of application was 1.0-10.0 ng ml(-1) of lomefloxacin, with a relative standard deviation of 3.8% (for a level of 5.0 ng ml(-1)) and a detection limit of 0.3 ng ml(-1). The method was applied to determination of lomefloxacin in human urine and serum samples. It was validated using HPLC as a reference method. Recovery levels of the method reached 100% in all cases.

Anti-Infective Agents↗
PubMed2001

Nonarrhythmic complications of acute myocardial infarction.

Complications of acute myocardial infarction can be categorized as nonarrhythmic or arrhythmic; the latter is discussed elsewhere. Patients are at risk for a number of potentially serious or fatal complications during or after the acute infarction phase. These include shock, left ventricular free wall rupture, rupture of the interventricular septum, papillary muscle rupture, ventricular pseudoaneurysm, and stroke. Right ventricular infarction, which is typically associated with inferior myocardial infarction, will also be discussed.

Aneurysm, False↗
PubMed2001

Oat-cell carcinoma of the prostate. Diagnosis, prognosis and therapeutic implications.

BACKGROUND: Any carcinoma of prostatic origin which is not an acinary adenocarcinoma of the prostate is considered to be an atypical carcinoma. One member of this group of atypical prostatic tumors is the oat-cell carcinoma, or small cell carcinoma (SCC) of the prostate. This variety of carcinoma constitutes the histologic basis of <1% of all prostatic neoplasms. METHODS: Between 1992 and 1997, four patients were diagnosed with SCC of the prostate at our hospital. In 3 of the 4 cases, the histopathological diagnosis was pure SCC, and in the 4th case there was a component of prostatic adenocarcinoma associated with the SCC. At the time of diagnosis, extracapsular extension of the tumor was present in all 4 cases, with T3 or higher stages in all of them (T(3A)N(0)M(1), T(3A)N(0)M(0), T(3B)N(0)M(1), and T(4)N(0)M(0)). Because of the presence of extracapsular extension, radiotherapy and radical surgery were ruled out for all 4 patients. They were all offered systemic chemotherapy with cyclophosphamide (1 g/m(2)), doxorubicin (50 mg/m(2)) and vincristine (1.2 mg/m(2)). This therapeutic protocol was carried out in only 2 cases. RESULTS: Survival was <1 year in the 3 patients with pure SCC, and the patient with a mixed tumor is alive with detectable disease 9 months after diagnosis. CONCLUSIONS: This poor vital prognosis in SCC stresses the need for early diagnosis a timely and appropriate therapeutic intervention in this condition.

Adult↗
PubMed2001

Defective natural killer and phagocytic activities in chronic obstructive pulmonary disease are restored by glycophosphopeptical (inmunoferón).

We have investigated both modifications in natural (innate) immunity caused by chronic obstructive pulmonary disease (COPD) and the effects of a glycophosphopeptical immunomodulator (Inmunoferón) treatment on COPD-associated immunoalterations. In a double-blinded clinical trial, 60 patients with COPD received glycophosphopeptical or placebo during 90 consecutive days at oral doses of 3 g/d. Fifty-six sex- and age-matched healthy control subjects were included as a reference group for immunologic parameters. Peripheral blood natural killer (PBNK) cell cytotoxic activity and phagocytic activity of peripheral monocytes/macrophages (Mo/Ma) and polymorphonuclear (PMN) cells were assessed at baseline and then again at the end of treatments. We found both PBNK activity and phagocytic activity to be significantly decreased in patients with COPD compared with levels in healthy volunteers. The treatment with glycophosphopeptical provoked significant stimulatory effects on PBNK cytotoxic activity. This stimulation was not mediated by an increase in CD3(-)CD56(+) NK cells. Further, glycophosphopeptical significantly increased the percentage of monocytes and PMNs that phagocytize Escherichia coli in vitro, as well as increased phagocytic indices. We conclude that peripheral blood cells of patients with COPD show clear defects in natural immunity that are partially rescued by glycophosphopeptical.

Adjuvants, Immunologic↗
PubMed2000

Liposomal amphotericin B and amphotericin B-deoxycholate show different immunoregulatory effects on human peripheral blood mononuclear cells.

Conventional preparations of amphotericin B (AmB) at established therapeutic doses are known to increase nonspecific immune responses. It remains to be established whether higher doses of the less toxic liposomal preparation of AmB maintains a beneficial effect on the immune response to fungal infections. Examination of the effect of treatment of human peripheral blood mononuclear cells from healthy subjects with various doses of both liposomal AmB (L-AmB) and deoxycholate AmB (d-AmB) on proliferation, cell viability, and percentage of apoptosis demonstrated that, although both L-AmB and d-AmB at low doses significantly increased nonspecific proliferative responses, L-AmB, but not d-AmB, treatment maintained this beneficial effect at higher doses. High doses of d-AmB, but not L-AmB, resulted in significantly decreased cell viability and increased apoptosis. This study provides further evidence in healthy human subjects for choosing L-AmB over conventional preparations in the clinical treatment of fungal infections requiring systemic high-dose treatment with AmB.

Adjuvants, Immunologic↗
PubMed2000

Expression of growth hormone receptor in the human brain.

This study was designed to investigate the presence of growth hormone receptor (GHR) expression in the human brain tissue, both normal and tumoral, as well as in the human glioblastoma cell line U87MG. Reverse transcription-polymerase chain reaction revealed the presence of GHR mRNA in all brain samples investigated and in U87MG cells. GHR immunoreactivity was also detected in this cell line using both immunocytochemistry and western blotting. All together, our data demonstrate the existence of GHR expression within the central nervous system (CNS), thus supporting a possible role for GH in the CNS physiology.

Blotting, Western↗
PubMed2000

A new method for the simultaneous analysis of growth and death of immunophenotypically defined cells in culture.

BACKGROUND: Internal standards have been used in flow cytometry methods to enumerate lymphoid subsets and hemopoietic progenitor cells ex vivo. However, the currently available methods cannot be readily applied to the analysis of cultured cells because of the frequent occurrence of cell death during in vitro assays. METHODS: This paper reports a new method for the enumeration of both viable and nonviable cells in culture. Cells were counted with the aid of an internal reference standard of microbeads, and live versus dead cell discrimination was performed using 7-amino-actinomycin D which allows the double staining of surface antigens. RESULTS: The method is more precise, accurate and sensitive than either conventional light microscopy-based or automated cell counting. Additionally, it may be used to accurately measure the number of apoptotic cells in a culture. RESULTS: Through the enumeration of surviving cells it is demonstrated that, when applied to the study of mitogen-activated T lymphocytes, current flow cytometry techniques (which do not use internal standards) for the study of the viability and apoptosis overestimate the fraction of viable cells and underestimate both the fraction of dead and apoptotic cells. CONCLUSIONS: The new method overcomes these limitations and is of use in the in vitro study of cell growth and apoptosis.

Apoptosis↗
PubMed2000

Heterogeneity of the genus Myrothecium as revealed by cell wall polysaccharides.

The polysaccharides obtained from the alkali-extractable, water-soluble fraction (F1SS) from the cell wall of Myrothecium verrucaria and Myrothecium atroviride were shown to be composed of beta-(1-->6)-galactofuranose fully substituted at O-2 by terminal residues of alpha-glucopyranose and alpha-glucuronic acid. Glucuronic acid was substituted at O-4 by glucopyranose in the Myrothecium species M. inundatum, M. setiramosum, M. prestonii, M. tongaense and M. roridum. The acidic polysaccharides from Phaeostilbella atra (=Myrothecium atrum) and Myrothecium gramineum lacked the backbone of 2,6 di-O-substituted galactofuranose and contained a high amount of O-5-substituted beta-galactofuranose. The structures of the polysaccharides isolated from Myrothecium cinctum and Myrothecium penicilloides were unrelated to each other and to the polysaccharides from the other species analysed. The usefulness of these polysaccharides as a characteristic for delimitation of the genus Myrothecium is discussed.

Ascomycota↗
PubMed2000

A quantitative study of fault tolerance, noise immunity, and generalization ability of MLPs

An analysis of the influence of weight and input perturbations in a multilayer perceptron (MLP) is made in this article. Quantitative measurements of fault tolerance, noise immunity, and generalization ability are provided. From the expressions obtained, it is possible to justify some previously reported conjectures and experimentally obtained results (e.g., the influence of weight magnitudes, the relation between training with noise and the generalization ability, the relation between fault tolerance and the generalization ability). The measurements introduced here are explicitly related to the mean squared error degradation in the presence of perturbations, thus constituting a selection criterion between different alternatives of weight configurations. Moreover, they allow us to predict the degradation of the learning performance of an MLP when its weights or inputs are deviated from their nominal values and thus, the behavior of a physical implementation can be evaluated before the weights are mapped on it according to its accuracy.

Journal Article↗
PubMed2000

[Reptiles from Cerro Colorado and its surroundings, Cumana, Sucre State, Venezuela].

An inventory of the reptiles that inhabit in Cerro Colorado and its surroundings, was performed from March, 1994 to March, 1995. There were reported 8 species of snakes and 7 of lizards enclosed in 4 and 5 families repectively. Aspects observed were ecolology as habitat, activity, reproduction and relative abundance. The more abundant species of lizards were: Cnemidophorus femniscatus, Ameiva bifrontata, (Teiidae), Tropidurus hispidus (Tropiduridae), Gonatodes vittatus and Hemidactylus mabouia (Gekkonidae) and the ophidians: Leptodeira annulata and Mastigodryas amarali (Colubridae). It is believed that the changes occurred in the zone influenced the increase of the relative abundance of the species Leptotyphlops goudotii (Leptotyphlopidae) arid Gymnophthalmus speciosus(Gymnophthalmidae) and perhaps in the disappearance of others that have been reported at the xerophitic or semixerophitic zones of the Sucre State of Venezuela.

Animals↗
PubMed2000

[Spatial and temporal variation of the fish community inhabiting the Laguna Grande de Obispo, Gulf of Cariaco, Sucre State, Venezuela].

The monthly species composition and the spatial and temporal variation of fish community of Laguna Grande de Obispo, Gulf of Canaco, Sucre State, Venezuela were analyzed. The samples were collected using two beach seines of different size from December 1995 to November 1996. A cluster analysis for stations inside the lagoon and time of capture showed 4 major groups, defined principally with ecological parameters of each area. Fishing with large seine in and outside the lagoon showed two large groups which were divided into 10 subgroups in function of station and time, while an inverse analysis of the same sample differentiated into 8 groups of species. based on distribution, dominance, and occurrence. Xenomeianiris brasiliensis, Mugil curema and Eucinostomus argenteus were the most abundant species in both time and space. An analysis of conglomerate on the whole fish community of the sampling period indicated the existence of two groups: i) the first half of the year including December 1995 and October 1996 and ii) the second half of the year. The distribution of fishes in relation to ecological factors is discussed.

Animals↗
PubMed2000

[Abundance and growth of Pinna carnea (Mytiloida: Pinnacea) juveniles in suspended-frame culture].

We quantified the abundance of juvenile Pinna carnea at Turpialito, Golfo de Cariaco, Venezuela, using collectors suspended at 8 m depth for 16 months and then evaluated their subsequent growth in suspended enclosures over 14 months in relation to concurrent measures of temperature and planktontonic food availability. All body components showed a rapid increase during the first four-five months. There was a decrease in somatic tissue mass and great variability in growth coincident at first spawning, suggesting a negative effect of gonadal production on somatic growth. A multiple regression analysis indicated a strong relationship between tissue growth and food availability as measured by organic sestonic matter. Although we determinated an adequated spat abundance for culture activities (80 spat per collector-30 x 60 cm), spat collection was limited, mainly from February through April. In addition to high variability in growth and negative influence of environmental factors during unfavorable periods, the muscles production required in 14 months, suggesting that P. carnea is not appropriate for commercial production of muscle. However, the high weight of all edible tissues mass attained (21 g) and the high survival rate in all experimentation (> 96%) suggests that P. carnea is fit for aquaculture.

Animals↗
PubMed1999

Analysing organophosphorus pesticides in wines using graphitized carbon black extraction cartridges.

A quick and simple method was developed to determine the residues of 15 organophosphorus pesticides of different polarity in grape wine, based on liquid-solid extraction with graphitized carbon black cartridges and capillary gas chromatography. Aliquots of diluted wine (10 ml wine + 40 ml deionized water) and 250 mg graphitized carbon black cartridges were used to extract the analytes. The pesticides were eluted with 2 x 0.5 ml acetone and 3 x 2.5 ml ethyl acetate/acetone (80:20). The eluates were then dried with anhydrous sodium sulphate and concentrated to 1 ml under a nitrogen current. After adding triphenylphosphate internal standard (i.s.), this extract was analysed by capillary gas chromatography using a nitrogen-phosphorus detector (GC-NPD). Pesticide recovery percentages at levels of 0.01 and 0.02 microgram/ml were between 74% and 111%, with a 2-13% relative standard deviation interval. The chromatograms of extracts had few co-extracted species peaks, with no analytical interference. Dilution of the grape wine samples removed most of the pigments, thus producing clear extracts. The results indicate that liquid-solid extraction from wine samples using graphitized carbon is fast (25 min per sample), efficient and reproducible for analysing organophosphorus pesticides of different polarity.

Chromatography, Gas↗
PubMed1999

Galactomannans from the cell walls of species of Paecilomyces sect. Paecilomyces and their teleomorphs as immunotaxonomic markers.

An alkali-extractable and water-soluble fraction (F1S) was obtained from cell walls of Paecilomyces variotii and species of the related genera Talaromyces, Byssochlamys and Thermoascus. The structure of the main polysaccharide of these fractions was studied and found to consist of a core of (1 --> 6)-alpha-mannopyranose partially substituted at 0.2 by chains of galactofuranose and shorter chains of mannopyranose. The differences in the regularity of the branching points and the length of the galactofuranose side chains are useful to distinguish between species. These differences were detected by immunological methods, since highly specific polyclonal antibodies were raised against these polysaccharides. Mycelium of P. variotii CBS 990.73A was stained by indirect immunofluorescence. The polysaccharides studied in this work differ from the one described for species from section Isarioidea, and this is another indication of the heterogeneity of the genus Paecilomyces.

Animals↗