Biomedical subjects

S Marín

Publications and source records attributed to S Marín.

At least 37 records · Page 2Linked to original sources

PubMed2004

Prediction of fungal growth and ochratoxin A production by Aspergillus ochraceus on irradiated barley grain as influenced by temperature and water activity.

Ochratoxin A (OTA) is a secondary metabolite of Aspergillus and Penicillium species, including Aspergillus ochraceus, a species that can be found in stored cereal grains such as barley. The objective of this study was to determine the effects of water activity (a(w), 0.80-0.99), temperature (10, 20, 30 degrees C), and A. ochraceus isolate differences on radial growth and OTA production in irradiated barley grains. The three isolates showed optimal conditions for growth and ochratoxin A production at 0.99 a(w) and 30 degrees C, with a marked decrease of growth rates and OTA production at the lowest levels of a(w) and temperature assayed. The minimum a(w) level for growth, observed in this study, was 0.85 and 0.90 a(w) for OTA production. Significant differences among the isolates were found. Lag phases prior to fungal growth and OTA production values were modelled by multiple linear regression and response surface models. These models could provide an approximate prediction of growth and OTA production.

Aspergillus ochraceus↗

PubMed2004

Incubation time and water activity effects on ochratoxin A production by Aspergillus section Nigri strains isolated from grapes.

AIMS: The objective of this study was to determine the temporal ochratoxin A (OTA) accumulation profile of Aspergillus section Nigri at different water activity (aw) levels. METHODS AND RESULTS: Two Aspergillus carbonarius and two Aspergillus niger aggregate strains isolated from grapes were tested in vitro for OTA accumulation at 25 degrees C on synthetic nutrient medium, over periods of 20 days at different aw levels. Results were modelled by a multiple linear regression and response surface predictive models were obtained. High levels of aw favoured OTA production by these moulds. Maximum amounts of OTA were found at the earlier growth states (5 days for A. carbonarius and 7-13 days for A. niger aggregate). CONCLUSIONS: Provided that A. section Nigri, and mainly A. carbonarius, play the main role in OTA presence in grapes, it would be critical to adjust the harvest and processing time to significantly reduce the chances for OTA accumulation. SIGNIFICANCE AND IMPACT OF THE STUDY: Ochratoxin A production by A. section Nigri has been shown for the first time to occur optimally after as little as 5 days on a grape-like medium.

Aspergillus niger↗

PubMed2004

Impact of essential oils on growth rate, zearalenone and deoxynivalenol production by Fusarium graminearum under different temperature and water activity conditions in maize grain.

AIMS: The effect of five essential oils (oregano, cinnamon, lemongrass, clove and palmarose) on growth rate, zearalenone (ZEA) and deoxynivalenol (DON) production by Fusarium graminearum strains was assessed. METHODS AND RESULTS: The influence of the essential oils was tested on irradiated maize at two concentrations (500 and 1000 mg kg-1), at different water activity (aw) (0.95 and 0.995) and temperature (20 and 30 degrees C) levels. At 0.995 aw all essential oils tested had an inhibitory effect on growth rate of F. graminearum at both temperatures studied. At this aw level, DON production in general was inhibited by all essential oils at 30 degrees C and, although palmarose and clove were the only essential oils with statistically significant inhibitory effect on ZEA production, an inhibitory trend was observed when cinnamon and oregano oils were added to maize grain. CONCLUSIONS: Antifungal and antimycotoxigenic activity of the essential oils assayed was shown to depend on environmental conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: It is apparent that essential oils should be considered as alternative preharvest natural fungicides. Further investigation on natural maize grain might be useful to study the effectiveness of these essential oils in the presence of natural mycoflora of maize grain.

Antifungal Agents↗

PubMed2003

Inhibitory effect of cinnamon, clove, lemongrass, oregano and palmarose essential oils on growth and fumonisin B1 production by Fusarium proliferatum in maize grain.

The effect of cinnamon, clove, oregano, palmarose and lemongrass oils on growth and FB1 production by three different isolates of F. proliferatum in irradiated maize grain at 0.995 and 0.950 aw and at 20 and 30 degrees C was evaluated. The five essential oils inhibited growth of F. proliferatum isolates at 0.995 aw at both temperatures, while at 0.950 aw only cinnamon, clove and oregano oils were effective in inhibiting growth of F. proliferatum at 20 degrees C and none of them at 30 degrees C. Cinnamon, oregano and palmarose oils had significant inhibitory effect on FB1 production by the three strains of F. proliferatum at 0.995 aw and both temperatures, while clove and lemongrass oils had only significant inhibitory effect at 30 degrees C. No differences were found using 500 or 1000 microg essential oil g(-1). At 0.950 aw, none of the essential oils had any significant effect on FB1 production. The results suggest that mainly cinnamon and oregano oils could be effective in controlling growth and FB1 production by F. proliferatum in maize under preharvest conditions.

Cinnamomum zeylanicum↗

PubMed2003

Efficacy of sorbates on the control of the growth of Eurotium species in bakery products with near neutral pH.

The effects of sorbic acid and potassium sorbate on growth of different Eurotium isolates when added to a bakery product analogue were tested under different environmental conditions. Water activity of the products was adjusted to values in the range of 0.75-0.90, and storage temperatures were in the range of 15-30 degrees C. Preservatives were added in concentrations ranging from 0.025% to 0.2%. It was observed that 0.025% and 0.05% concentrations always enhanced the isolates growth, while 0.1% had little preservative effect. Finally, even the highest concentration (0.2%) was not suitable as it only controlled fungal growth under certain water activity and temperature levels. It was concluded that these weak-acid preservatives are not useful when added to bakery products with near to neutral pH.

Bread↗

PubMed2003

SEM study of water activity and temperature effects on the initial growth of Aspergillus ochraceus, Alternaria alternata and Fusarium verticillioides on maize grain. Scanning electron microscopy.

A scanning electron microscopy (SEM) study of the effect of water activity (a(w)), temperature and fungal interactions on the very early phases of Aspergillus ochraceus, Alternaria alternata and Fusarium verticillioides development on maize grains was carried out. Germination and growth of individual fungal strains were assayed at 0.92, 0.95 and 0.98 a(w), and 20 and 30 degrees C. Hyphal lengths were measured on micrographs taken by SEM at different periods of incubation. A. alternata had the highest linear growth at 0.98 a(w), and was the only species able to grow under all conditions tested, whereas A. ochraceus was not able to germinate at 0.92 a(w) at any temperature assayed. F. verticillioides demonstrated a different behaviour depending on growth temperature. Fungal interactions were studied at 0.95a(w) and 30 degrees C. A. ochraceus germination was inhibited when it was co-inoculated with one or two of the other species. A. alternata showed an increased growth rate when growing together with the other fungi, whereas growth of F. verticillioides was significantly inhibited when paired with A. ochraceus.

Alternaria↗

PubMed2003

Involvement of the kappa-opioid receptor in the anxiogenic-like effect of CP 55,940 in male rats.

We have studied the possible interaction between three selective opioid-receptor antagonists, nor-binaltorphimine (NB: kappa) (5 mg/kg), cyprodime (CY: mu) (10 mg/kg) and naltrindole (NTI: delta) (1 mg/kg), and the cannabinoid receptor agonist CP 55,940, in the modulation of anxiety (plus-maze) and adrenocortical activity (serum corticosterone levels by radioimmunoassay) in male rats. The holeboard was used to evaluate motor activity and directed exploration. CP 55,940 (75 microg/kg, but not 10 microg/kg) induced an anxiogenic-like effect, which was antagonised by NB. The other effects of CP 55,940 (75 microg/kg), a decreased holeboard activity and stimulation of adrenocortical activity, were not antagonised by any of the three opioid receptor antagonists. CY and NTI, when administered alone, induced marked reductions in motor activity, anxiogenic-like effects and stimulation of adrenocortical activity. The selective kappa-opioid receptor antagonist NB, on its own, did not modify the level of anxiety but stimulated adrenocortical activity. We provide the first pharmacological evidence about the involvement of the kappa-opioid receptor in the anxiogenic-like effect of CP 55,940.

Animals↗

PubMed2003

Antifungal activity of volatile compounds generated by essential oils against fungi commonly causing deterioration of bakery products.

AIMS: To investigate the volatile fractions of 16 essential oils for activity against the more common fungi causing spoilage of bakery products, Eurotium amstelodami, E. herbariorum, E. repens, E. rubrum, Aspergillus flavus, A. niger and Penicillium corylophilum. METHODS AND RESULTS: The study applied 50 microl of pure essential oils in a sterilized filter paper, were carried out at pH 6 and at different water activity levels (0.80-0.90). First, a wheat flour based agar medium was used, where cinnamon leaf, clove, bay, lemongrass and thyme essential oils where found to totally inhibit all microorganisms tested. These five essential oils were then tested in sponge cake analogues, but the antifungal activity detected was much more limited. CONCLUSION: Five essential oils showed potential antifungal capacity against all species tested, over a wide range of water availability. Their activity, however, seems to be substrate-dependent. More research is needed to make them work in real bakery products, as in the preliminary study limited effectiveness was found. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential of the cinnamon leaf, clove, bay, lemongrass and thyme essential oils against species belonging to Eurotium, Aspergillus and Penicillium genus has been demonstrated.

Agar↗

PubMed2003

Modified atmosphere packaging for prevention of mold spoilage of bakery products with different pH and water activity levels.

A sponge cake analog was used to study the influence of pH, water activity (aw), and carbon dioxide (CO2) levels on the growth of seven fungal species commonly causing bakery product spoilage (Eurotium amstelodami, Eurotium herbariorum, Eurotium repens, Eurotium rubrum, Aspergillus niger, Aspergillus flavus, and Penicillium corylophilum). A full factorial design was used. Water activity, CO2, and their interaction were the main factors significantly affecting fungal growth. Water activity at levels of 0.80 to 0.90 had a significant influence on fungal growth and determined the concentration of CO2 needed to prevent cake analog spoilage. At an aw level of 0.85, lag phases increased twofold when the level of CO2 in the headspace increased from 0 to 70%. In general, no fungal growth was observed for up to 28 days of incubation at 25 degrees C when samples were packaged with 100% CO2, regardless of the aw level. Partial least squares projection to latent structures regression was used to build a polynomial model to predict sponge cake shelf life on the basis of the lag phases of all seven species tested. The model developed explained quite well (R2 = 79%) the growth of almost all species, which responded similarly to changes in tested factors. The results of this study emphasize the importance of combining several hurdles, such as modified atmosphere packaging, aw, and pH, that have synergistic or additive effects on the inhibition of mold growth.

Ascomycota↗

PubMed2002

Risk assessment of the use of sub-optimal levels of weak-acid preservatives in the control of mould growth on bakery products.

The hurdle technology approach was used to prevent fungal growth of common contaminants of bakery products including isolates belonging to the genera Eurotium, Aspergillus and Penicillium. Several levels (0.003%, 0.03% and 0.3%) of calcium propionate, potassium sorbate and sodium benzoate were assayed on a model agar system in a full-factorial experimental design in which the other factors assayed were pH (4.5, 6 and 7.5) and a(w) (0.80, 085, 0.90 and 0.95). Potassium sorbate was found to be the more suitable preservative to be used in combination with the common levels of pH and a(w) in Spanish bakery products. Sub-optimal concentrations (0.003% and sometimes 0.03%) led to an enhancement of fungal growth. None of the preservatives had a significant inhibitory effect at neutral pH.

Antifungal Agents↗

PubMed2002

Combined effects of weak acid preservatives, pH and water activity on growth of Eurotium species on a sponge cake.

The combined effects of weak acid preservatives (sorbate, benzoate and propionate), pH (6.0, 7.5) and water activity (a(w)) levels (0.80, 0.85, 0.90) on growth of four Eurotium species isolated from bakery products on a sponge cake analogue were studied. Even though it is universally known that these preservatives are much more effective at lower pH values, we chose a 6-7.5 level to correlate with the pH of the Spanish cake product studied. In general, 0.3% doses of all three preservatives were effective only when they were applied at pH 6.0 and at 0.80-0.85 a(w). Potassium sorbate was clearly the most effective in inhibiting growth of all isolates. Under the conditions tested, application of all three preservatives added at 0.03% acted as growth promoter of all isolates rather than having a preservative effect.

Ascomycota↗

PubMed2000

The effect of fungal competition on colonization of maize grain by Fusarium moniliforme, F. proliferatum and F. graminearum and on fumonisin B1 and zearalenone formation.

The effect of water activity (0.98, 0.95, 0.93) and temperature (15, 25 degrees C) on fungal growth and toxin production from interactions between isolates of Fusarium moniliforme and F. proliferatum producing fumonisin, and an isolate of F. graminearum producing zearalenone, incubated at the same time on irradiated maize grains were determined in vitro. Populations (CFUs) of F. moniliforme and F. proliferatum were reduced to a greater or lesser extent by the presence of F. graminearum under all conditions tested, while that the presence of F. moniliforme or F. proliferatum had a minor inhibitory effect on fungal populations of F. graminearum. Fumonisin B, production by F. proliferatum was inhibited under all conditions tested, while fumonisin B1 production by F. moniliforme was inhibited at 15 degrees C and enhanced at 25 degrees C in the presence of F. graminearum. The level of zearalenone was not significantly modified in the presence of F. moniliforme and F. proliferatum under the conditions tested.

Analysis of Variance↗

PubMed2000

[Emerging mycotoxin control. Current limits and regulations].

Emerging mycotoxins are of a great importance due to their high occurrence in foods and feeds and their implication in pathologies. There is a need to control them both in pre- and post-harvest. However, the increasing drawbacks of chemical decontamination methods, makes the use of preventive methods more attractive. These are based on avoiding growth of mycotoxigenic fungi and mycotoxin accumulation in these substrates (by using reduced aw levels, and modifying other storage conditions) and the early detection of these mycotoxins by using simple and fast analysis techniques. At the same time, it is important to know the effect that industrial processing has on mycotoxin concentration in foods and feeds, because it may reduce the toxin content. Finally, maximum limits of mycotoxin concentration should be established for both foods and feeds.

English Abstract↗

PubMed1999

Two-dimensional profiles of fumonisin B1 production by Fusarium moniliforme and Fusarium proliferatum in relation to environmental factors and potential for modelling toxin formation in maize grain.

This study has examined in detail the effect of temperature (7-37 degrees C) and water availability (water activity, a(w), 0.89-0.97) on fumonisin B1 (FB1) production by an isolate of Fusarium moniliforme and F. proliferatum on irradiated maize grain after incubation for 28 days. The optimum conditions for F. moniliforme and F. proliferatum were 30 degrees C at 0.97 a(w) and 15 degrees C at 0.97 a(w), respectively. The maximum concentrations were 2861 mg kg(-1) and 17,628 mg kg(-1) dry wt. maize grain, respectively. At marginal a(w)/temperature conditions for growth (e.g. 0.89-0.91 a(w)) no FB1 was detected (<0.1 mg kg(-1)). A high variability was found between replicates for F. moniliforme, but not for F. proliferatum. These data were used to construct two-dimensional diagrams of all the a(w) x temperature conditions favourable for FB1 production for the first time. The data were also subjected to a polynomical regression, which demonstrated that there was a very good fit for the 15-30 degrees C range of temperature and at 0.97 a(w). However, at marginal environmental conditions this was not possible. This suggests that it may be possible to predict within a limited environmental range the potential for significant FB1 production.

Carboxylic Acids↗

PubMed1999

Impact of radiotherapy on local control and survival in uterine sarcomas: a retrospective study from the Grup Oncologic Català-Occità.

PURPOSE: In order to provide more information for the clinician and to analyze the impact of radiation therapy on the loco-regional disease-free interval (LRFI), disease-free interval (DFI) and specific overall survival (OS), a multicentric retrospective study of uterine sarcomas has been undertaken using cases reported to the Grup Oncològic Català-Occità (GOCO). PATIENTS AND METHODS: One hundred three patients were selected for this study with a median follow-up period of 49 months. Patients were restaged using the FIGO classification for endometrial adenocarcinoma. Radiotherapy was administered postoperatively to the entire pelvis in 52% of cases (54/103) and was combined with brachytherapy in 24 patients. Mean given dose was 48 Gy, with a 95% confidence interval of 45 to 50 Gy. Variables have been tested for homogeneity between hospitals. Univariate and multivariate analyses have also been carried out. RESULTS: Mean age of the selected patients was 59 years (range 35-84). Stages were distributed as follows: 66 patients (64%) in Stage I; 16 in Stage II (15.5%); 12 in Stage III (11.5%); 9 patients in Stage IVa (9%). Pathological distribution was 41.5% leiomyosarcoma, 39% mixed Mullerian tumours, 16.5% stromal sarcomas, and 2.9% of a miscellaneous group. Overall survival for the entire group was 63.7% and 56% at 2 and 5 years, respectively. Probability of LRFI reached 59.8% at 2 years and 57.4 at 5 years. The DFI at 2 and 5 years were 52.9 % and 48.7%, respectively. The LRFI probability was 41% and 36% at 2 and 5 years, respectively, without radiotherapy and reached 76% at 2 and 5 years among those patients treated with radiotherapy. There was also an increase in DFI probability because of the effect of radiotherapy, from 35% to 68.5% and from 33% to 53% at 2 and 5 years, respectively. The overall survival probability for patients treated with radiotherapy was 76% and 73% at 2 and 5 years, respectively and 51% at 2 years and 37% at 5 years without radiotherapy. Multivariate analysis demonstrated that radiotherapy improved LRFI, DFI, and overall survival. CONCLUSION: We conclude that postoperative radiotherapy in our series of patients diagnosed with uterine sarcoma has an impact on loco-regional and disease-free progression intervals and survival.

Adult↗

PubMed1999

Control of growth and fumonisin B1 production by Fusarium verticillioides and Fusarium proliferatum isolates in moist maize with propionate preservatives.

The effect of propionic acid, its sodium salt or a commercial formulation of propionates (0.03, 0.05 and 0.07%), on growth and fumonisin B1 production by Fusarium verticillioides and F. proliferatum isolated was evaluated on irradiated maize at different water activities (aw, 0.93, 0.95, 0.98) and temperatures (15, 25 degrees C). The four isolates grew at all aw x temperature treatments in the absence of propionates. At the highest propionate concentration tested (0.07%), however, growth was restricted to 0.98 aw, for F. proliferatum isolates but not for those of F. verticillioides. Inhibition of growth was maximum when propionates were added in the acid form. In the presence of low propionate concentrations (0.03%), growth was sometimes enhanced probably due to assimilation of these compounds by the fungus. Water activity, temperature, concentration and source of propionate, as well as most two-, three-, four-, and five-way interactions had a significant influence on growth of Fusarium isolates. None of the assayed treatments had any effect on fumonisin B1 production by F. verticillioides isolates. For F. proliferatum, higher fumonisin B1 production occurred in the absence of propionates, and in general concentration decreased with increasing doses of preservatives. Single factors (aw, propionate concentrations and temperature) and temperature x aw and propionate concentration x temperature interactions had a significant effect on fumonisin production (p < 0.01). Moreover, propionate concentration was the single most important factor, besides temperature, which affected fumonisin B1 production.

Carboxylic Acids↗

PubMed1998

Colonisation and competitiveness of Aspergillus and Penicillium species on maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum.

The effects of different steady-state water activity levels (a(w), 0.93, 0.95 and 0.98) and temperature (15 and 25 degrees C) on colonisation patterns of Aspergillus and Penicillium spp., when colonising irradiated maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum were assayed in terms of populations (colony forming units, CFUs g grain(-1)), seed infection and colonisation rates. The activity of F. moniliforme and F. proliferatum in grain reduced the presence of Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus to some extent, particularly at 15 degrees C and higher water availabilities (0.95-0.98 a(w)). In contrast, colonisation patterns of Penicillium implicatum on maize grain were unaffected by either Fusarium spp. in terms of CFUs or seed infection. Correlations were made between CFUs, seed infection, growth rates and niche overlap indices and hyphal interactions to try and link key indicators of competitiveness and dominance by an individual species.

Aspergillus↗

PubMed1998

Effect of water activity and temperature on growth and ochratoxin production by three strains of Aspergillus ochraceus on a barley extract medium and on barley grains.

Aspergillus ochraceus Wilhelm is a widespread storage fungus that has been isolated from grains such as barley. The objective of this study was to determine the effects of water activity (a(w)), temperature, time and their interactions on (a) growth on a barley extract agar medium, (b) growth on barley grains and (c) ochratoxin production on barley grains by three strains of A. ochracieus. For the three A. ochreceus isolates examined (NRRL 3174, 3.113 and 3.38), optimal a(w) levels for growth on agar media were in the range 0.98-0.96, with temperature optima of 30 degrees C for two of the isolates and 25-30 degrees C for the other isolate. Growth was observed at 10 and 37 degrees C, but only at higher a(w) levels assayed. Two dimensional profiles were constructed for the range of a(w) and temperature conditions that allow growth of the three isolates. Maximum growth on barley grains was reached at 30 degrees C, at both a(w) levels assayed (0.96 and 0.98), with fungal growth rates in the 4-5 mm day(-1) range. Maximum amounts of ochratoxins were produced at the highest a(w) treatment (0.98 a(w)) and after a three-week incubation time at 25-30 degrees C. The range of ochratoxin concentrations varied considerably, from 1.7 to 12,949 ppm, depending on the a(w) and temperature interactions.

Aspergillus ochraceus↗