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M L Fernández

Publications and source records attributed to M L Fernández.

At least 19 recordsLinked to original sources
PubMed2005

[Usefulness of anti-transglutaminase antibodies in the diagnosis of celiac disease].

BACKGROUND: Anti-transglutaminase antibodies have been proposed as a useful tool in the diagnosis and follow-up of celiac disease. AIM: To compare anti-transglutaminase antibodies with the classical antibodies used to diagnose celiac disease. MATERIAL AND METHOD: Patients who underwent duodenal biopsy for suspected celiac disease were selected if they had the following serum antibody samples: antiendomysial IgA, anti-transglutaminase IgA, antigliadin IgG, and antigliadin IgA. A diagnostic value of each of these antibodies was established according to the final diagnosis, taking the duodenal biopsy as the reference. RESULTS: One hundred twenty-two patients with duodenal biopsy and serologic markers for celiac disease were selected. Thirty-six patients were children (< 14 years-old) and 86 were adults. A diagnosis of celiac disease was made in 41 patients (26 children and 15 adults). Of the 15 adults, only 2 (13%) presented typical malabsorption syndrome. The sensitivity and specificity of anti-transglutaminase antibodies was 100% and 98% respectively compared with values of 97% and 98% for antiendomysial IgA, 85% and 97% for antigliadin IgA, and 97% and 92% for antigliadin IgG antibodies. CONCLUSIONS: The diagnostic value of anti-transglutaminase antibodies is high in celiac disease. These antibodies may be useful as a screening test to select candidates for duodenal biopsy.

Adult↗
PubMed2003

Accumulation and transformation of DSP toxins in mussels Mytilus galloprovincialis during a toxic episode caused by Dinophysis acuminata.

The time course of several outbreaks of the diarrhetic shellfish poisoning (DSP) producer Dinophysis acuminata and the consequent kinetic of accumulation and loss of toxins in mussels Mytilus galloprovincialis feeding on them was studied. Samples of mussels and seawater were frequently (2-3 times a week) collected from a raft in the Ri;a de Vigo. DSP toxins content of mussels and water was analyzed by HPLC-FD and phytoplankton was quantified in an inverted light microscope. Only okadaic acid (OA) and some of its conjugated forms (OA CF), estimated by enzymatic hydrolysis, were found in the plankton samples obtained, comprised mainly of D. acuminata cells. The main accumulated form in mussels was OA reaching a maximum of 10.1 microg OA g(-1) in the digestive gland (d.g.) in 16 days, falling below the quarantine level (ca. 2 microg OA g(-1) d.g.) by 45 days. The low polarity conjugated forms (LPCF), estimated by hexane extraction, accounted for 6.2% of the total toxin burden of the mussels. To quantify the rates of the processes involved in the accumulation, transformation and loss of the toxins, two dynamic models, a one-compartment and a two-compartment, including OA and its conjugated forms as variables were designed and implemented. The one-compartment model provided a good fit to the OA and LPCF actual data (r(2)=0.92 and r(2)=0.94, respectively). The two-compartment model did not fit the data markedly better than its one-compartment counterpart (r(2)=0.93 and r(2)=0.95, for OA and LPCF, respectively). High hydrolysis rates were estimated for most of the OA CF, which means that these forms came largely from the ingested plankton. The low estimated acylation rates support the previous point and suggest that the formation of LPCF by direct acylation of the OA is of little importance in M. galloprovincialis. Only in cases where the intoxication period is very long, can the formed acyl-derivatives be important, because they seem to accumulate for a long time in the mussels, as suggested by the low hydrolysis and depuration rates estimated from model fitting.

Animals↗
PubMed2001

Influence of amino acids on okadaic acid production.

Okadaic acid (OA) (1)) was the first example of a group of polyether toxins known to be produced by marine microalgae, which are responsible for the natural phenomena known as Diarrhetic Shellfish Poisoning (DSP) red tides. It is also a highly selective inhibitor of protein phosphatases type 1 (PP1) and 2A (PP2A), as well as being a potent tumour promoter. For these reasons, OA is an extremely useful tool for studying cellular processes and an important standard for polluted shellfish control. In this paper, we report on a double objective: to improve the production of toxins and verify the apparent participation of amino acids in the formation of these polyethers by monitoring their influence on the promotion of growth, total cell yield and increased in toxicity in Prorocentrum lima of the PL2V strain in batch cultures, in a modified K medium.

Amino Acids↗
PubMed2001

Toxin composition of the toxic dinoflagellate Prorocentrum lima isolated from different locations along the Galician coast (NW Spain).

The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galician rias (Vigo and Pontevedra) was investigated by high performance liquid chromatography coupled with fluorimetric detection. Boiling and freeze/thaw/hydrolyse methodology were applied during extraction to detect OA, DTX1, DTX2 and their esterified derivatives. OA and DTX2 were detected in both free and esterified form, the latter always in very low amounts, whilst DTX1 was always present in the free form. This indicate that the hypothesized self-protection mechanism of toxin storage in the less active esterified forms does not seem to apply to DTX1. A slight increase in the toxin concentration per cell was found during growth, although toxin composition did not vary appreciably. Toxin production and toxin profile varied significantly depending on the isolate. Four groups of P. lima were differentiated by cluster analysis according to their toxin composition. It is noteworthy that one of the clusters comprised all the strains collected from one location characterised by its geographical isolation, whereas the other clusters consisted of isolates from different locations. The differences in the toxin profile from P. lima strains and from the DSP contaminated shellfish, together with the very good correlation between Dinophysis spp occurrence and DSP toxicity in shellfish, support that these planktonic species are the main agents responsible for DSP events in Galicia.

Animals↗
PubMed2000

Erythema nodosum: etiologic and predictive factors in a defined population.

OBJECTIVE: To examine the frequency and features of erythema nodosum (EN), establish disease associations, and identify the optimal set of predictors for the occurrence of secondary EN. METHODS: We performed a retrospective study of an unselected population of patients 14 years and older with biopsy-proven EN diagnosed at a referral hospital between 1988 and 1997. Patients were classified as having either idiopathic EN or EN secondary to other diseases if the skin nodules occurred in the context of a well-defined disease, or if there was a precipitating event in close temporal proximity to the onset of EN. RESULTS: One hundred six patients (82 women) were diagnosed as having biopsy-proven EN. At the time of diagnosis, no precipitating events or underlying diseases were identified in 36.8% of patients. Sarcoidosis and nonstreptococcal upper respiratory tract infections (URI) were the most common conditions associated with secondary EN. Only 1 of 35 patients with an initial diagnosis of idiopathic EN and a followup of at least 1 year was finally diagnosed as having secondary EN. The best predictive model of secondary EN included an abnormal results on a chest radiograph, a previous history of nonstreptococcal URI, and a significant change in antistreptolysin O (ASO) titer in 2 consecutive determinations performed in a 2-4-week interval. Also, the presence of peripheral synovitis, a positive tuberculin skin test, and a history of diarrhea suggested the presence of secondary EN. This model showed high sensitivity and specificity. CONCLUSION: Idiopathic EN is common. A basic procedure including careful medical history-taking, a physical examination for peripheral synovitis, 2 consecutive ASO determinations, a tuberculin skin test, and chest radiography may be sufficient to diagnose EN.

Biopsy↗
PubMed2000

Ovine placental lactogen and ovine prolactin: partial proteolysis and conformational stability.

The high-resolution structure of ovine placental lactogen (oPL) and ovine prolactin (oPRL), not yet established in detail, was probed by limited proteolysis with the Glu-specific protease from Staphylococcus aureus V8. While in hGH there were no cleavage sites inside of any of the four alpha-helices, the analysis of the fragments obtained after partial proteolysis of oPL showed a site of cleavage at the putative third helix, suggesting that this helix is partially unwound at this point. The partial proteolysis of the rest of the molecule was compatible with a similar folding pattern for oPL, hGH and pGH, on the basis of the crystal structure of these last hormones. In the case of oPRL, proteolytic cleavage occurred at Glu residues which would be located at the end of the first helix and the beginning of the second in the hGH folding model, suggesting that these helices are shorter in oPRL than in hGH. In order to gain further insight on the folding of these molecules, circular dichroism and intrinsic fluorescence measurements were used to examine the effect of denaturing conditions on oPL and oPRL. After exposure to 6 M guanidine the unfolding of both proteins was completely reversed upon elimination of the denaturing agent. In contrast, exposure to pH 3.0 caused an irreversible decrease in the alpha-helical content in both hormones, most striking for oPL, indicating that this hormone is less stable than oPRL or hGH.

Amino Acid Sequence↗
PubMed2000

Automated image analysis for monitoring oxidative burst in macrophages.

OBJECTIVE: To evaluate oxidative bursts induced by phorbol myristate acetate in phagocytes at the single-cell level by automated image analysis. STUDY DESIGN: The generation of reactive oxygen species was quantitatively expressed by means of histograms displaying the percentage of cells corresponding to each of the total optical densities measured. RESULTS: Macrophage subpopulations were quantitatively defined. This method allows detailed analysis of the amount of formazan per cell and the sites of deposition of blue precipitate in each cell. CONCLUSION: Image analysis is a reliable quantitative, single-cell assay for studying various cellular characteristics associated with macrophage functions.

Animals↗
PubMed1999

Effect of the selection marker on the viability and plasmid stability of two human proteins with neurotrophic action expressed in Escherichia coli.

Most developed expression systems rely on the production of fusion proteins or the change of selection marker increasing genetic stability to avoid toxicity of heterologous proteins to Escherichia coli host cells. According to this, we analyzed the effect of the selection marker on the viability and plasmid stability of vectors pYMK5 and pYMK7 that codify neurotrophic factors brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). We also analyzed the influence of two different lac promoter inducers on these parameters. We found that the addition of IPTG to culture medium produced a significant decrease of viability and plasmid stability for both expression vectors compared with values reached with lactose. There was no increase of both parameters when we changed the selection marker, so we can conclude that, in our case, a change of antibiotic does not solve the problem of low plasmid stability values.

Brain-Derived Neurotrophic Factor↗
PubMed1999

Role of distinct subpopulations of peritoneal macrophages in the regulation of reactive oxygen species release.

It has been reported in vitro that during the respiratory burst of phagocytic cells the superoxide anion production per cell shows a negative relation with the cell density. This process has been described as autoregulation. The aim of this work was to analyze the superoxide anion production in thioglycollate-elicited peritoneal macrophage exudates to evaluate the importance of the peritoneal cavity environment in the autoregulation process. 12-O-tetradecanoylphorbol-13-acetate (PMA) was used to stimulate the respiratory burst and superoxide anion production was measured evaluating the intracellular formazan deposits that precipitate as a result of nitro blue tetrazolium (NBT) reduction. We have demonstrated a negative correlation between superoxide anion production and cell density in the peritoneal cavity in macrophages challenged with PMA. The response of individual cells was analyzed by means of an image analyzer, measuring the amount of formazan per cell and cell-size changes during the process of activation. The results revealed that the decrease in individual cell response as a function of higher cell densities were due to a significant increase in the amount of basal reaction macrophages. Concomitantly, the number of reactive cells remained unchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anion production was observed. This phenomenon was demonstrated in SENCAR and Balb/c strains. However, macrophages from SENCAR mice showed greater superoxide anion production than those from Balb/c. The differences between strains could be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice. Based on this property, macrophages from SENCAR mice were stimulated with opsonized zymosan, a particulate stimulus that reflects the interaction macrophage-microorganism during the phagocytic process. This data will contribute to the knowledge of infection control. We conclude that variations in basal reaction cells modulates the macrophage activation response when excess macrophages are recruited to the peritoneum. This is demonstrated using different stimuli, thus suggesting that this response may be applied to a wide variety of stimuli-macrophage interactions. The differences between strains may be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice.

Animals↗
PubMed1996

Selenium speciation by coupling vesicle mediated HPLC with off-line ETAAS and on-line focused microwave digestion HG-AAS detection.

A novel High Performance Liquid Chromatography (HPLC) method for the separation of selenium species with specific detection by off-line Electrothermal Atomization Atomic Absorption Spectrometry (ETAAS) or on-line focused microwave digestion (MW) Hydride Generation Atomic Absorption Spectrometry (HG-AAS) is described. Vesicular mobile phases of the cationic surfactant didodecyldimethylammonium bromide (DDAB) have been evaluated for the liquid chromatographic separation of inorganic selenium (selenite and selenate) and different selenoaminoacids (selenocystine, selenomethionine and selenoethionine) on a C(18) reversed-phase column modified by DDAB molecules. The effects of different parameters (pH, buffer and vesicle concentrations) of the mobile phase on the retention times have been determined. The detection limit for selenium with the proposed off-line HPLC-ETAAS method has been found to be 5 microg/L of Se. The detection limit using HPLC-"on line" focused microwave digestion-HG-AAS has been found to be 1 microg/L of Se, with a precision (repeatability) better than +/- 5%. The latter proved to be an exceptional on-line real-time chromatographic detector for selenium speciation purposes.

Journal Article↗
PubMed1996

Detection of okadaic acid esters in the hexane extracts of Spanish mussels.

Two types of low polar derivatives of OA and dinophysitoxins have been reported in shellfish or in phytoplankton: 7-0-acyl esters containing a fatty acyl group attached through the 7-OH group and diol esters in which the carboxylic group of the toxins has been esterified. These compounds cannot be directly detected by liquid chromatography and fluorimetric detection as 9-anthryldiazomethane derivatives, owing in the first case to their low polarity and high molecular weight, and in the second case because they have the carboxylic group esterified. All of them must be hydrolysed before derivatization to be detected as Adam derivatives of the corresponding non-acylated toxins. In the Lee procedure, after extraction of the shellfish digestive glands with 80% methanol, a liquid-liquid partition with a non-polar solvent such as hexane is carried out in order to remove non-polar lipids. The presence of non-polar toxins was investigated in Spanish mussels and confirmed in the hexane layer, usually discarded in conventional extraction procedures, by analysis of the alkaline hydrolysis products. A preferred solubilization of these toxins in a non-polar solvent like hexane is reported. The inclusion of a hydrolytic step of the hexane extract in the general procedure is suggested in order to monitor the contribution of non-polar diarrhoetic shellfish poisons (DSPs) to the total DSP shellfish toxicity. This is the first report of DSPs other than OA and DTX2 in Spanish mussels.

Animals↗
PubMedDate not supplied

[Listeria monocytogenes infections in the adult. Clinical and microbiological issues of a changing disease].

Thirty-one cases of human listeriosis seen from 1971-1999 were reviewed. cases were grouped as follows: Group I composed of 14 patients were studied in the period 1971-1984; and group II composed of 17 cases studied in the period 1985-1999. We tried to assess changes in the incidence, clinical findings and outcome in both periods. The incidence of listeriosis remained constant along the years, 1.2 cases/20,000 discharges. The mean age of the patients significantly increased along the years (55 11 years versus 68 12 years; p 0.002). 77% of cases had one or more underlying diseases predisposing to listeriosis. We observed an increasing number of listeriosis in patients without chronic diseases in recent years. Listeriosis presented as meningitis or primary sepsis. Mortality was 61% and was strictly associated with the severity of the underlying disease. Patients with meningoencephalitis and seizures had a worse prognosis. We did not observe differences in mortality of patients who were treated with beta-lactam monotherapy in comparison with those who were treated with beta-lactam/aminoglucoside combination. Cotrimoxazole was uniformly successful treatment of human listeriosis in this series.

Adult↗