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Biomedical subjects

A Valero

Publications and source records attributed to A Valero.

At least 19 recordsLinked to original sources
PubMed2006

Management of microbiological safety of ready-to-eat meat products by mathematical modelling: Listeria monocytogenes as an example.

The recent Commission Regulation (EC) No 2073/2005 establishes microbiological criteria in foods. For the pathogen Listeria monocytogenes in the category ready-to-eat foods able to support its growth, other than those intended for infants and for special medical purposes, two different microbiological criteria are proposed: (i) L. monocytogenes levels should be <100 cfu/g throughout the shelf-life of the product, (ii) absence in 25 g of the product at the stage before the food has left the immediate control of the food business operator, who has produced it. The application of either the first or the second of these criteria depends on whether or not the manufacturer is able to demonstrate that the level of L. monocytogenes in the food product will not exceed 100 cfu/g throughout its shelf-life. This demonstration should be based on physico-chemical characteristics of the target product and consultation of scientific literature, and, when necessary, on quantitative models and/or challenge tests. Once the characteristics of the product as well as scientific literature show that the pathogen has potential to grow on a specific food commodity, it seems adequate to use quantitative models and/or perform challenge tests to study the extent to which L. monocytogenes could grow. In this study, we aim to illustrate with an example in cooked ham the application of quantitative models as a tool to manage the compliance with these criteria. Two approaches were considered: deterministic and probabilistic, in three different commercial brands (A, B, and C). The deterministic approach showed that the limit 100 cfu/g was exceeded largely at the end of the shelf-life of all three; however, when reducing the storage time, the level of L. monocytogenes remained below 100 cfu/g in B. The probabilistic approach demonstrated very low percentiles corresponding to 100 cfu/g; when reducing the storage time, percentiles for three products increased, especially in products B and C (from 4.92% to 75.90%, and from 0.90% to 73.90%, respectively). This study shows how different storage times influence the level of L. monocytogenes at the end of the shelf-life of cooked ham, and, depending on the level reached, the microbiological criterion applied should be different, as stated above. Beside this, the choice of either point-estimate or probabilistic approach should be determined by the competent sanitary authority, and, in case of selecting the second approach, a certain percentile for the level 100 cfu/g should be established.

Animals↗
PubMed2006

Effect of preincubation temperature and pH on the individual cell lag phase of Listeria monocytogenes, cultured at refrigeration temperatures.

The impact of precultural temperature and pH on the distribution of the lag phase of individual Listeria monocytogenes cells was assessed during preincubation at 7 degrees C, using a dilution protocol to obtain single cells, and optical density measurements to estimate the individual lag phase. Firstly, the pure temperature effect (37, 15, 10, 7, 4 and 2 degrees C) was investigated on a subsequent growth at 7 degrees C and pH 7.4. Secondly, low precultural temperatures (10, 7 and 4 degrees C) were combined with a controlled pH at 7.4 and 5.7 with a subsequent growth at 7 degrees C and at different pH values (7.4, 6.0 and 5.5). For all temperature-pH combinations, the individual cell lag phase was determined using a three-phase linear growth model. It was observed that at low precultural temperatures (2, 4 and 7 degrees C), a high proportion of L. monocytogenes cells were able to grow at 7 degrees C with almost no lag phase, consequently, the resulting distributions were positively skewed. Beside this, the variability observed was lower than at higher precultural temperatures. Regarding the precultural pH effect, at pH 7.4 the mean values of the lag phases were shorter at lower preincubation temperatures; while at pH 5.7 small pH transitions produced shorter individual lag phases at all precultural temperatures. The quantification of the effect of precultural conditions on the individual cell lag phase duration would improve the accuracy of the existing growth models, especially when a series of processing and storage steps are linked together in a process model or exposure assessment. Distributions will be fitted to the data for every set of conditions, generating useful tools for further risk assessment purposes.

Colony Count, Microbial↗
PubMed2006

Hair analysis for veterinary drug monitoring in livestock production.

This review summarizes the basic information and applications concerning the use of hair analysis for the detection of misuse of therapeutic and anabolic agents in livestock animals. Hair biology, hair-shaft structure and the mechanisms of drug incorporation are described, considering the different factors which can affect the deposition. Sampling and extraction methods are reviewed with special attention to the particularities of this matrix, while the use of different analytical techniques is discussed, taking into account the concentration and the sensitivity required for drug detection. Advantages, drawbacks, promising prospects and possible applications of this technique in the future are also discussed.

Animals↗
PubMed2006

A simplified LC-DAD method with an RP-C12 column for routine monitoring of three sulfonamides in edible calf and pig tissue.

Use of an RP-C(12) analytical column with a mobile phase at pH 4.5 enabled excellent chromatographic separation and quantification of sulfadiazine (SDZ), sulfamerazine (SMR), and sulfamethazine (SMZ) in edible calf and pig tissue (muscle and liver). Tissue samples were extracted with acetonitrile, centrifuged without further clean-up, and analyzed by LC-DAD. The proposed conditions are useful for a rapid and reliable screening of the SDZ, SMR, and SMZ content of calf and pig tissue at concentrations lower than the maximum residue level (MRL) (LOQ between 27 and 55 ppb). Separation of some possible SMZ metabolites should be further investigated.

Animals↗
PubMed2006

Electroporation of cells in microfluidic devices: a review.

In recent years, several publications on microfluidic devices have focused on the process of electroporation, which results in the poration of the biological cell membrane. The devices involved are designed for cell analysis, transfection or pasteurization. The high electric field strengths needed are induced by placing the electrodes in close proximity or by creating a constriction between the electrodes, which focuses the electric field. Detection is usually achieved through fluorescent labeling or by measuring impedance. So far, most of these devices have only concerned themselves solely with the electroporation process, but integration with separation and detection processes is expected in the near future. In particular, single-cell content analysis is expected to add further value to the concept of the microfluidic chip. Furthermore, if advanced pulse schemes are employed, such microdevices can also enhance research into intracellular electroporation.

Animals↗
PubMed2006

Sensitization to Anisakis simplex s.l. in a healthy population.

The main objective of this study was to determine the degree of sensitization to Anisakis simplex s.l. in healthy population. Using the determination of specific IgE, we studied the seroprevalence against A. simplex s.l. in blood donors selected at random in the region of Antequera (Southern Spain). We detected 22.1%. The immunoblotting technique revealed a band of approximately 60 kDa in the serum of individuals who also exhibited high values of specific IgE against A. simplex s.l. This band would be useful for diagnosis.

Adolescent↗
PubMed2006

Novel approach to control sulfamethazine misuse in food-producing animals by hair analysis.

The presence of sulfamethazine residues in pig and calf hair was compared with the residual levels encountered in the corresponding edible tissues (liver and muscle) as a consequence of drug administration. Sulfamethazine up to 84.7 mg kg-1 was found in calf hair samples after a pharmacological treatment, with a significant effect of hair pigmentation. High concentrations of the parent drug were detected in calf hair for 4 weeks after administration, when sulfamethazine residues were no longer detectable in the corresponding edible tissues. In a similar way, pig hair also accumulated sulfamethazine residues up to 40.5 mg kg-1, which was more than the amount detected in the corresponding muscle and liver samples at slaughter. Hair analysis seems a suitable tool to improve the efficacy of regulatory controls, and thus the safety of the food chain and to discourage the improper use of sulfamethazine in animal farming.

Animals↗
PubMed2006

Effect of desloratadine on epithelial cell granulocyte-macrophage colony-stimulating factor secretion and eosinophil survival.

BACKGROUND: Second-generation antihistamines are H(1) receptor antagonists and may have additional anti-inflammatory effects. OBJECTIVE: The aims of the study were to evaluate the effect of desloratadine (DL) on cytokine secretion by epithelial cells from both nasal mucosa (NM) and polyps (NP), and on eosinophil survival primed by epithelial cell secretions. METHODS: Epithelial cells were cultured and stimulated with fetal bovine serum (FBS), IL-1beta or TNF-alpha with and without DL for 24 h. Culture supernatant cytokines concentration were measured by ELISA. Peripheral blood eosinophils were incubated with human epithelial cell conditioned media (HECM) and DL. Eosinophil survival was assessed by Trypan blue dye exclusion. Results are expressed as mean+/-SEM of cytokine concentration (pg/mL) or eosinophil survival index (%). RESULTS: FBS increased granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), IL-6, IL-8, and TGF-beta(1) secretion in epithelial cell cultures from both NM and NP. Only GM-CSF secretion was significantly (P<0.05) inhibited by a dose-response of DL compared with positive controls, in both NM (10(-5) m: 125+/-36 pg/mL, 10(-6) m: 95+/-22 pg/mL vs. control: 256+/-91 pg/mL, n=6) and NP (10(-5) m: 80+/-29 pg/mL, 10(-6) m: 109+/-45 pg/mL vs. control: 333+/-212 pg/mL, n=6). DL also showed an inhibitory effect on HECM-induced eosinophil survival from both NM and NP. At 72 h, DL significantly (P<0.01) inhibited eosinophil survival induced by HECM from NM (10(-5) m: 19.9+/-5.5%, n=9; 10(-6) m: 28.7+/-7.7%, n=9) and NP (10(-5) m: 6.2+/-2.8%, n=11) compared with HECM alone (NM: 42.1+/-7.3%; NP: 45.3+/-8.1%). CONCLUSION: The inhibitory effects of DL on epithelial cell GM-CSF secretion and on eosinophil survival induced by epithelial cell secretions, suggest that this H(1) antagonist may regulate eosinophil inflammation in upper airways.

Adolescent↗
PubMed2006

Linking quantitative exposure assessment and risk management using the food safety objective concept: an example with Listeria monocytogenes in different cross-contamination scenarios.

A practical approach was used to achieve specified food safety objectives (FSOs) by incorporating risk assessment methodology. A series of cross-contamination scenarios at the retail level were evaluated in a spreadsheet and ranked according to their level of risk, and the degree to which they exceeded an FSO for Listeria monocytogenes (100 CFU/g) was determined. Percentiles and analyses of variance were used to identify which scenarios would be most likely not to achieve the FSO. It was also possible to incorporate into the model the effect of additional risk management interventions (e.g., hand washing method) by using "what if" scenarios analysis. The highest risk corresponded to the use of the same gloves to handle contaminated meat and then sliced ham compared with the safer method of using different gloves to handle each product. Nevertheless, in all scenarios bacterial concentrations could be higher than 10(8) CFU/g. A significant lack of knowledge regarding the transfer rates of L. monocytogenes was revealed, which provided the model with an important uncertainty component. The "what if" scenarios analysis based on the scenario representing handling food with bare hands followed by hand washing (scenario 2) revealed that the hand washing procedure had less impact than expected. This study illustrates the use of scenarios to model the most effective food processes and thus provide risk managers with appropriate information on which to base their decisions.

Analysis of Variance↗
PubMed2006

Iberian study of aeroallergens sensitisation in allergic rhinitis.

BACKGROUND: Allergic rhinitis (AR) is a prevalent allergic disease in Iberian countries, but there are no recent epidemiological studies that characterize this pathology according to clinical classification and aeroallergens sensitisation. This is a clinical study, representative of each country METHODS: Descriptive, observational cross-sectional, population-based study carried-out in Portugal and Spain. 3397 consecutive patients (5 regions in Spain and 3 regions in Portugal) were selected for clinical observation and skin prick tests were carried out using the same panel of standardized aeroallergens. RESULTS: 3225 patients (aged 10-50 years old) completed the study (IC 95%, SE 15). Intermittent rhinitis makes up 36% of the entire sample. Of them, intermittent AR mild forms represented 82% in Spain and 92% in Portugal that is, 87% for Iberian countries. Persistent types of rhinitis showed exactly the same rate of severity in Portugal and Spain, 44% mild and 56% moderate/severe. Seasonal forms represent 37% while 63% were perennial. BA was present in 49% of AR patients. There were significant differences between aeroallergens according to the different regions considered. Mites and grass pollens are the most relevant aeroallergens in Spanish and Portuguese AR patients, while Alternaria showed higher positive rates among 10-20 year old patients. CONCLUSIONS: This study characterizes the AR patients in Iberian countries according to the ARIA classification. No correlation was observed between this classification and the conventional (seasonal/perennial). Our results also characterize the allergic cutaneous pattern of aeroallergen sensitisation using the same panel of standardized allergens and show differences between the different regions analysed.

Adolescent↗
PubMed2005

In vivo larvicidal activity of monoterpenic derivatives from aromatic plants against L3 larvae of Anisakis simplex s.l.

In view of the lack of an effective pharmacological treatment against human anisakiosis, a disease produced by L(3) larvae of the genus Anisakis present in raw fish, we studied the in vivo larvicidal effect of certain monoterpenic derivatives against L(3) of A. simplex s.l. The aldehydic monoterpene citral and the alcoholic citronellol, when they are administered together to the larvae of the nematode at the concentration of 46.90 mg/0.5 ml in olive oil, achieve 85.90% and 67.53% dead L(3), respectively, and also stop rats suffering gastrointestinal hemorrhages produced by the larvae.

Acyclic Monoterpenes↗
PubMed2005

Anisakid parasites of two forkbeards (Phycis blennoides and Phycis phycis) from the Mediterranean coasts of Andalucía (Southern Spain).

An epidemiological survey of anisakids was carried out on 209 specimens of greater forkbeard (Phycis blennoides) and 58 of forkbeard (Phycis phycis) captured off the Mediterranean coasts of Andalucía (southern Spain). Four species of nematodes were identified: Anisakis simplex s.l., Anisakis physeteris, Hysterothylacium aduncum and Hysterothylacium fabri. The total prevalence was 62.06% in the forkbeard and 58.85% in the greater forkbeard. The highest values of prevalence (56.90%), mean intensity (5.21) and mean abundance (2.96) were all obtained for H. fabri in the forkbeard. The most frequent parasite in the greater forkbeard was H. aduncum with 51.20% prevalence and values of 3.00 and 1.53 for mean intensity and mean abundance, respectively. The infestation parameters were also analyzed according to the host length, observing a maximum of parasitized fish (91.67%) in samples of P. blennoides longer than 40 cm, while in P. phycis, the highest prevalence (82.35%), conditioned by H. fabri parasitization, was found in fish with lengths between 30 and 35 cm.

Animals↗
PubMed2005

Nasal and bronchial response to exercise in patients with asthma and rhinitis: the role of nitric oxide.

BACKGROUND: Physical exercise is associated with a decrease in nasal resistance in rhinitis and an increase in bronchial resistance in asthma. The objective was to evaluate the relationship between the levels of nasal nitric oxide (nNO) and exhaled bronchial nitric oxide (eNO) with bronchial responses to exercise in patients with rhinitis and asthma. METHODS: We submitted 24 subjects with asthma and rhinitis to an exercise test. A decrease in FEV(1)> or =15% was considered positive. The volume of the nasal cavity and the minimal cross-sectional area (MCA) was evaluated by means of acoustic rhinometry (AR), and nNO and eNO were evaluated by chemoluminiscence. The measurements were recorded at baseline, 15 and 50 min after the end of the exercise test. RESULTS: The exercise test was positive in 17 cases. Fifteen minutes after exercise test, the nasal volume increased by 57% (P < 0.0001) and was still increased by 30% after 50 min (P < 0.0001). There was no correlation between decrease in FEV(1) and increase in nasal volume. The baseline value of nNO was 1185 +/- 439 ppb, and the value at 15 and 50 min was 1165 +/- 413 and 1020 +/- 368 ppb, the latter value being significantly lower (P < 0.01) than the baseline. The baseline value of eNO was 21 +/- 19 ppb, with no significant differences at 15 and 50 min. There was no significant correlation between either the decrease in FEV(1) and the nasal response, or the baseline eNO and nNO values. CONCLUSIONS: The nasal and bronchial response to exercise is completely different in rhinitis and asthma; in the former, an increase in nasal volume occurs, while in the latter there is a drop in FEV(1). There is no relationship between the values of nasal or exhaled NO and the nasal and bronchial response after exercise.

Adult↗
PubMed2005

Ochratoxin A-producing species in grapes and sun-dried grapes and their relation to ecophysiological factors.

AIMS: To explain the dominance of OTA-producing fungal species in sun-dried grapes for special wine production through an ecophysiological approach. METHODS AND RESULTS: Grapes at different ripening stages, sun-dried grapes and raisins were analysed for fungal presence, and isolates identified. Aspergillus section Nigri incidence in grapes increased with grape maturation. In the ecophysiological study five isolates (Alternaria alternata, Cladosporium herbarum, Penicillium decumbens, Aspergillus carbonarius, A. niger aggregate and A. section Nigri uniseriate) were inoculated in SNM medium at four a(w) (0.82-0.97) and incubated at 20, 30 and 40 degrees C for 18 d. Isolates were also inoculated in pairs to evaluate fungal interactions recording their growth rates and indexes of dominance. Aspergillus section Nigri grew in a wider range of temperature and a(w), had higher growth rates than the others under most of the conditions tested and showed behaviour usually dominant. CONCLUSIONS: The presence of A. section Nigri is predominant in grapes during harvesting and sun-drying period likely because of a better adaptation to hot and humid environment. SIGNIFICANCE AND IMPACT OF THE STUDY: The duration of the drying period should be reduced as much as possible without compromising the quality of the final product, or drying the grapes in controlled chambers with dry hot air flow.

Mitosporic Fungi↗
PubMed2005

Usefulness of montelukast to prevent adverse reactions to COX-2 selective inhibitors: a case report.

Nonsteroidal anti-inflammatory drug (NSAID)-sensitivity is a frequent condition in patients with chronic urticaria and/or asthma. The physiopatologic process underlying respiratory and cutaneous reactions probably involves an increased production of cysteinyl leukotrienes. Cyclooxygenase 2 (COX-2) selective inhibitor, has been proposed as the main alternative to control pain and inflammatory diseases in these patients. However, a small percentage of patients with NSAID-induced skin reactions does not even tolerate COX-2 selective inhibitors. We report a very infrequent case of a patient with NSAID, paracetamol and COX-2 selective inhibitors sensitivity in whom we induced tolerance to paracetamol and celecoxib using the leukotriene receptor antagonist montelukast prior to oral challenges.

Acetates↗
PubMed2004

In vitro development of the fish parasite Hysterothylacium aduncum from the third larval stage recovered from a host to the third larval stage hatched from the egg.

Anisakids are parasitic nematodes of fish worldwide, producing economic and human health concerns. It is thus important to ascertain their in vitro life cycle in laboratory studies. Here we describe the in vitro development of third-stage larvae (L3) of Hysterothylacium aduncum isolated from blue whiting Micromesistius poutassou, to the hatching of L3 from eggs obtained from H. aduncum worms grown in GLIT medium (a modified mixture of Yaeger's LIT [Liver Infusion Tryptose] and Grace's media) at pH 4.0, 13 degrees C and with 5% CO2 in air. Under these conditions, L3 recovered from fish developed to mature adults (3.4 to 6.2 cm in length), with oviposition starting from Day 26 in culture. Fertilized eggs (mean size 64 x 52 microm) had a thick, rugose eggshell and were larger than unfertilized ones (mean size 49 x 42 microm), whose eggshells were thin and smooth. Eggs laid during the first and second week of oviposition, and maintained in 2.8% NaCl solution at 13 degrees C, developed to L3. Under these maintenance conditions, between 20.6 and 52.5% of the eggs laid during the first week developed into larvae. Motile larvae, enclosed in a sheath, hatched from between 2 and 11% of these eggs. The larvae started to hatch 23 d after deposition. These larvae were 144 to 215 microm in length, enclosed in a 237 to 305 microm-long sheath. This GLIT culture medium may help to study the biology of this and other anisakids.

Animals↗