Neutrophil-to-lymphocyte ratio but not monocyte-to-HDL cholesterol ratio nor platelet-to-lymphocyte ratio correlates with early stages of lower extremity arterial disease: an ultrasonographic study.

OBJECTIVE: The role of inflammatory markers as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-high-density lipoprotein-cholesterol ratio (MHR), and platelet-to-lymphocyte ratio (PLR) in cardiovascular diseases has been widely investigated in recent years. In the context of lower extremity arterial disease (LEAD), this association has been mainly studied in the advanced stages. The aim of our study was to investigate the role of these inflammatory markers in all stages of LEAD, including early ones, using ultrasonography as diagnostic tool, together with ankle-brachial index (ABI) determination. PATIENTS AND METHODS: In this cross-sectional observational study, we enrolled 240 patients undergoing ultrasonographic evaluation of the lower limb arteries and ABI determination because of symptoms suggestive of LEAD or presence of known cardiovascular risk factors. RESULTS: In our study population, we found that ultrasonographic categories of LEAD were associated with NLR, but not with MHR and PLR. CONCLUSIONS: These results confirm that a specific pattern of inflammation can be found in all stages of LEAD, including early ones.

Conyza bonariensis as an alternative host for Colletotrichum species in Argentina.

AIMS: This study investigated the diversity of Colletotrichum isolates recovered from Conyza bonariensis leaves through the use of morphological characteristics, growth rate, carbon sources utilization and phylogenetic analysis. METHODS AND RESULTS: In all, 30 Colletotrichum isolates recovered from C. bonariensis leaves showing symptoms of disease were included in the present study. Based on the analysis of morphology and sequences, the isolates were distributed into six Colletotrichum species complexes. The concatenated alignment of GAPDH and ITS sequences showed that 20 out of 30 isolates were included in four species complexes which comprise the most important pathogens causing anthracnose in soybean or anthracnose and stalk rot in maize: C. truncatum, C. orchidearum, C. gloeosporioides and C. graminicola. The remaining 10 isolates were included in the C. boninense and C. destructivum species complexes or could not be assigned to any complex with the available information. CONCLUSION: Weeds belonging to genus Conyza are host to soybean and maize potential pathogenic species of Colletotrichum and could have a role as inoculum reservoir for cross contamination in the agroecosystem. SIGNIFICANCE AND IMPACT OF THE STUDY: The combined use of morphological, kinetics and physiological parameters of growth and phylogenetic analysis in Colletotrichum isolates from Conyza leaves allowed the detection of species complexes previously not identified in Argentina.

Subclinical atherosclerosis and endothelial dysfunction in patients with polymyalgia rheumatica: a pilot study.

Objective: The aim of the study was to investigate endothelial function in treatment-naïve polymyalgia rheumatica (PMR) patients and its modification during steroid therapy, in relation to changes in clinical and laboratory parameters.Method: This prospective observational study involved patients with a new diagnosis of PMR according to provisional American College of Rheumatology/European League Against Rheumatism 2012 criteria, who were naïve to steroid therapy, and control subjects matched for age, gender, and comorbidities. All participants underwent clinical and vascular ultrasound evaluations at baseline and after 1, 3, 6, and 12 months of steroid therapy. For the study of endothelial function, we evaluated the brachial artery reactivity, which has emerged as the most well-established technique used in adults, by assessing flow-mediated dilatation (FMD), which measures the endothelium-dependent vasodilatation.Results: Sixteen newly diagnosed PMR patients were compared with a population of 16 matched controls. FMD values in all subjects showed an inverse correlation with the values of erythrocyte sedimentation rate and C-reactive protein. At baseline, the FMD of PMR patients was significantly lower than controls and remained significantly lower with respect to controls until the sixth month of therapy, despite a clinical improvement already being evident after 1 month of therapy.Conclusions: PMR is characterized by an important chronic subclinical inflammatory component. This pilot study demonstrates that affected patients show endothelial dysfunction that slowly responds to steroid therapy. Further studies are needed to investigate the clinical relevance of these observations and, in particular, to monitor the cardiovascular risk profile of PMR patients.

Low molecular weight heparin as cause of liver injury: case report and literature review.

Low molecular weight heparins (LMWH) are a class of drugs including various molecules that inhibit predominantly the factor V of coagulation and are used in a wide range of clinical settings for the management of venous thromboembolism and acute coronary syndrome. Despite LMWH are considered safe and associated with a lower incidence of side effects compared to unfractioned heparin, it is worth considering that the use of LWMH can be associated with complications. Some of these, such as bleeding and thrombocytopenia, are well-known, whereas other ones are often underestimated leading to a diagnostic delay. In this case report, we describe a case of a 73-years-old man who recently started nadroparin for deep vein thrombosis presenting with acute hepatitis. The diagnostic workup of drug-induced liver injury (DILI) requires the exclusion of other causative agents and temporal association between the initiation of the culprit drug and hyper aminotransferasemia. This clinical case analyzes how to deal with a suspicion of DILI and consider LWMH as a potential cause of DILI, which requires a modification of the anticoagulant treatment.

Development of a third-generation biosensor to determine sterigmatocystin mycotoxin: An early warning system to detect aflatoxin B1.

A third-generation enzymatic biosensor was developed to quantify sterigmatocystin (STEH). It was based on a glassy carbon electrode modified with a composite of the soybean peroxidase enzyme (SPE) and chemically reduced graphene oxide. The optimal conditions to construct the biosensor were obtained through an experimental design based on the response surfaces methodology. The experiments were performed in 0.1 mol L-1 phosphate buffer solution, pH 5. Amperometric measurements were carried out at - 0.09 V vs Ag/AgCl (3 mol L-1 NaCl). The biosensor showed a lineal response in the concentration range from 6.9 × 10-9 to 5.0 × 10-7 mol L-1. The limit of detection was 2.3 × 10-9 mol L-1 for a signal: noise ratio of 3: 1. Values of the apparent Michaellis-Menten constant, KMapp, obtained by using both Lineweaver-Burk and Eadi-Hofstee methods were (1.5 ± 0.2) × 10-6 and (1.2 ± 0.2) × 10-6 mol L-1, respectively. STEH was analyzed in corn samples spiked with STEH, with an average recovery of 96.5%. The biosensor was also used to determine STEH in corn samples inoculated with the Aspergillus flavus fungus, which is an aflatoxins producer. Considering that STEH is a precursor of aflatoxin B1 (AFB1) in its biological transformation, its decrease over time was related to the production of AFB1. The STEH concentration determined using the biosensor was in very good agreement with that determined by HPLC.

Influence of crop residues, matric potential and temperature on growth of Exserohilum turcicum an emerging maize pathogen in Argentina.

Northern corn leaf blight (NCLB) caused by Exserohilum turcicum is an endemic foliar disease in the Argentinean maize production area. Before applying a control method, it is essential to focus on factors that lead to the survival and conservation of E. turcicum inoculum. However, there is little information about the life cycle of this emerging pathogen in our country. The objective of the present work was to analyse the growth ability of three E. turcicum isolates under different type and conditions of maize, wheat and soybean residues, matric potential, temperature and their interactions. Statistical analysis demonstrated a significant effect of three factors on growth rate: residues-based media, matric potential and temperature. Among them the major effect was produced by matric potential followed by temperature. Although there were no significant differences in the growth rate among different residues types, the range of conditions in which growth occurred was different. According to these results, soybean residues would allow a better survival of E. turcicum inoculum under no-tillage system and providing an inoculum source for maize infections in subsequent year. SIGNIFICANCE AND IMPACT OF THE STUDY: Exserohilum turcicum is an emerging pathogen in Argentina that has caused significant economic losses in different maize growing areas. However, at present there is a lack of information about the life cycle of this fungal pathogen. The present study shows the influence of abiotic factors such as temperature and water potential on the growth of E. turcicum on different crop residues used in rotations with maize under no-till system cultivation. According to our results, soybean residues allowed the pathogen growth in a wider range of conditions compared to wheat and maize residue, providing an inoculum source for maize infections in subsequent season.

Association between peripheral arterial disease and cardiovascular risk factors: role of ultrasonography versus ankle-brachial index.

OBJECTIVE: Most studies on atherosclerotic processes include peripheral arterial disease diagnosis only if patients report symptoms suggestive of peripheral arterial disease and/or an instrumental demonstration of lower limbs perfusion deficit is provided, rather than the sole presence of atherosclerotic lesions localized at lower limbs, this attitude leading to ignore early stages of the disease. To overcome these limitations, we have proposed a new ultrasonographic semiquantitative score to better identify all disease stages. The aim of this study is to compare ultrasonography versus ankle-brachial index in the association between peripheral arterial disease and cardiovascular risk factors. PATIENTS AND METHODS: This cross-sectional observational study included subjects undergoing lower limbs evaluation through ultrasonography and ankle-brachial index determination because of symptoms suggestive of peripheral arterial disease or presence of known cardiovascular risk factors. Associations between ultrasonography and ankle-brachial index with cardiovascular risk factors were assessed by first fitting logistic regression models and then comparing the respective areas under the Receiver Operating Characteristic and 95% confidence intervals. RESULTS: The areas under the Receiver Operating Characteristic for each cardiovascular risk factors were consistently larger in magnitude for ultrasonography compared with ankle-brachial index, this comparison being statistically significant for age, male gender, smoking status, hypertension, diabetes mellitus and previous cardiovascular events. CONCLUSIONS: Our study demonstrates that ultrasonography is a better method to screen peripheral arterial disease respect to ankle-brachial index in order to identify all disease stages. These findings are useful in particular when including peripheral arterial disease as organ damage marker in cardiovascular risk stratification.

A novel ultrasound-based vascular calcification score (CALCS) to detect subclinical atherosclerosis.

OBJECTIVE: To quantify non-coronary vascular calcifications (VC) in asymptomatic patients at low-intermediate cardiovascular risk by a new color Doppler ultrasound (DUS)-based score (the carotid, aortic, lower limbs calcium score, CALCs), and to correlate this score with classical parameters associated with cardiovascular risk [carotid intima media thickness (IMT), and arterial stiffness (AS)]. PATIENTS AND METHODS: All consecutive asymptomatic patients who underwent a screening DUS of non-coronary circulation were evaluated and patients at low-intermediate cardiovascular risk were selected according to Framingham risk score (FRS). Among them, we enrolled 70 patients with US evidence of VC and 71 age, sex and FRS matched controls. The presence of VC was correlated with classical markers of cardiovascular risk, such as AS and intima-media thickness (IMT). AS, expressed as pulse wave velocity (PWV) and arterial distensibility, carotid IMT and CALCs were measured for both groups. AS and c-IMT were assessed by a new Radio-Frequency (RF) DUS-based method. CALCs was generated by our previously described B-mode DUS-based method according to number/size of VC in 11 non-coronary segments (range 0-33). RESULTS: Patients with VC presented higher AS and IMT values than controls (PWV 8.34±0.98 m/s vs. 6.74±0.68 m/s, p<0.0001; arterial distensibility 267±12 mm vs. 315±65 mm, p=0.001; IMT 687±132 mm vs. 572±91 mm, p<0.0001). Mean CALCs of patients with VC was 8.41±7.78. CALCs were significantly correlated with c-IMT (p<0.0001; r=0.3), PWV (p<0.0001; r=0.4) and arterial distensibility (p=0.002; r=-0.1). CONCLUSIONS: DUS-based CALCs is highly correlated with other validated markers of subclinical atherosclerosis, such as c-IMT and AS. Our results demonstrated the ability of CALCs to identify individual predictive factors beyond the traditional risk factors by quantifying an interesting and novel step of the atherogenic process. Future studies on larger series and with adequate follow up are necessary to confirm these results and to evaluate the role of this new marker in monitoring calcific atherosclerosis progression.

New modalities of ultrasound-based intima-media thickness, arterial stiffness and non-coronary vascular calcifications detection to assess cardiovascular risk.

BACKGROUND: Carotid intima-media thickness (c-IMT), arterial stiffness (AS) and vascular calcification (VC) are now considered important new markers of atherosclerosis and have been associated with increased prevalence of cardiovascular events. An accurate, reproducible and easy detection of these parameters could increase the prognostic value of the traditional cardiovascular risk factors in many subjects at low and intermediate risk. Today, c-IMT and AS can be measured by ultrasound, while cardiac computed tomography is the gold standard to quantify coronary VC, although concern about the reproducibility of the former and the safety of the latter have been raised. Nevertheless, a safe and reliable method to quantify non-coronary (i.e., peripheral) VC has not been detected yet. AIM: To review the most innovative and accurate ultrasound-based modalities of c-IMT and AS detection and to describe a novel UltraSound-Based Carotid, Aortic and Lower limbs Calcification Score (USB-CALCs, simply named CALC), allowing to quantify peripheral calcifications. Finally, to propose a system for cardiovascular risk reclassification derived from the global evaluation of "Quality Intima-Media Thickness", "Quality Arterial Stiffness", and "CALC score" in addition to the Framingham score.

Biomarkers of low-grade inflammation in primary varicose veins of the lower limbs.

OBJECTIVE: To analyze serum biomarkers of CVD in selected patients with primary axial reflux of great saphenous vein in one or both lower limbs. PATIENTS AND METHODS: Ninety-six patients affected by uncomplicated varicose veins, were enrolled in the study. A unilateral, primary axial reflux in great saphenous veins was detected in 54 patients (U-CVD group) and a bilateral one in 42 (B-CVD group). Sixty-five age and sex-matched subjects without venous reflux were enrolled as controls. Mean venous pressure of both lower limbs at the distal great saphenous vein (mGSVP) and venous reflux were measured by continuous-wave Doppler ultrasound and echoduplex scanning, respectively. Reactive Oxygen Species (ROS), tissue Plasminogen Activator (t-PA) and its Inhibitor 1 (PAI-1) activities, Hematocrit (HTC), White Blood Cells (WBC), Neutrophyls (NEU), Platelets (PLT), Fibrinogen (FIB) and Blood Viscosity (BV) were assessed in blood samples drawn from the antecubital vein. RESULTS: B-CVD group showed higher fibrinogen values (p < 0.005) and higher mean venous pressure (0 < 0.0001) in comparison to controls, while U-CVD did not. No difference was found between both groups and controls for all the other parameters. CONCLUSIONS: Increased fibrinogen levels in patients with bilateral varicose veins may represent an early warning signal, as it could be associated to the long-term progression of chronic venous disease.

Production of Fusarium verticillioides biocontrol agents, Bacillus amyloliquefaciens and Microbacterium oleovorans, using different growth media: evaluation of biomass and viability after freeze-drying.

The aims of this study were to compare the viability and biomass production of B. amyloliquefaciens and M. oleovorans in different growth media, and the efficiency of a freeze-drying method as a possible formulation process. B. amyloliquefaciens and M. oleovorans were grown in 100 ml of four different media. Media water activity was modified at 0.99, 0.98, 0.97 and 0.96. Nutrient yeast dextrose broth (NYDB) and molasses soy powder (MSB) media were selected and survival levels of cells were determined before and after the freeze-drying process. B. amyloliquefaciens showed the highest survival after freeze-drying when grown in NYDB medium at 0.99 a(w), whereas, at 0.98, 0.97 and 0.96 a(w), the highest survival was obtained in MSB medium. M. oleovorans showed the highest survival in MSB medium at 0.99 a(w). MSB medium was select for biomass production due to high growth and survival after freeze-drying.

Kinetic and mechanistic aspects of sensitized photodegradation of ß-lactam antibiotics: microbiological implications.

Amoxicillin (Amx) and cephalexin (Cfx) are ß-lactam antibiotics widely used in human and veterinary medicine. Two points of interest surrounding these molecules are the photodegradation of the molecules and their microbiological implications, as well as the persistence and bioaccumulation in the environment which may cause resistance to bacterial strains. The kinetic and mechanistic aspects of the photosensitized degradation of Amx and Cfx have been studied in water at pH 7.4 and 10 by stationary and time-resolved methods. Kinetic evidence indicates that the Rose Bengal-sensitized photooxidation of Amx at pH 7.4 proceeds via O(2)((1)Δ(g)) and O(2•-) mechanisms while at pH 10 the degradation path occurs, principally, via O(2)((1)Δ(g)). For Cfx, this process is attributed to O(2)((1)Δ(g)) and O(2•-). Photoproducts, which arise from the addition of oxygen atoms and subsequent oxidation of the groups -CH(3) to -COOH, were detected. For both antibiotics the bacteriostatic activity decreases in parallel to their photodegradation. The results of this study could potentially help scientists to better understand and predict the photodegradability of these antibiotics on living organisms and in different environmental compartments.

Impact of two bacterial biocontrol agents on bacterial and fungal culturable groups associated with the roots of field-grown maize.

AIMS: To assess the impact of Bacillus amyloliquefaciens and Microbacterium oleovorans on bacterial and fungal groups associated to the roots of field-grown maize. METHODS AND RESULTS: Identification and count of bacterial and fungal culturable populations associated to the roots of maize seedlings, changes in culturable community structure according to the richness and diversity indexes concept and shifts in microbial activity through analysis of cellulolytic, ammonification and nitrification potentials were determined, in relation to kernel treatment with biological control agents. Following the treatment of maize kernels with B. amyloliquefaciens at 10(7) CFU ml(-1), an increase in bacterial diversity was observed at the rhizoplane of resultant seedlings. Bacterial richness was significantly increased at the root inner tissues of seedlings treated with Mic. oleovorans. Fusarium, Aspergillus, Penicillium and Trichoderma were the main fungal genera isolated and there population sizes were unequally affected by the addition of biocontrol agents. CONCLUSIONS: Numbers and types of isolated bacteria and fungi changed in response to the addition of biocontrol agents, while microbial activity remained unchanged with respect to control. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides an insight of the effects of proven biocontrol agents on micro-organisms naturally associated to the target crop.

Characterization of the polarization sensitivity anisotropy of a near-field probe using phase measurements.

Amplitude and phase measurements of the near-field generated by isolated subwavelength apertures in a gold film are presented. The near-field distribution of such a structure is complex and the measured signal strongly depends on the electric field components effectively detected by the experimental setup. By comparing this signal with 3D vectorial calculations we are able to determine which electric field components are effectively measured. The sensitivity of the phase distribution is key to this measurement. The proposed characterization technique should prove extremely useful to calibrate a Scanning near-field optical microscopy (SNOM) beforehand in order to retrieve quantitative information on the polarization of the field distribution under study.

Natural maize phenolic acids for control of aflatoxigenic fungi on maize.

Natural phytochemicals may be an alternative to synthetic chemicals for controlling fungal growth and mycotoxin production in stored maize. A key to progress in this field is to select the best natural maize phytochemicals to be applied in a storage maize ecosystem. This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) and ferulic acid (FA) alone at concentrations of 20 to 30 mM and in 5 combinations on Aspergillus flavus Link and A. parasiticus Speare populations and aflatoxin B(1) production. Studies on Aspergillus population and aflatoxin B(1) production were carried out in maize grain in relation to a water activity a(w) of 0.99, 0.97, 0.95, and 0.93. CA and FA at concentrations of 25 to 30 mM, respectively, and CA-FA mixture T9 (25 + 30 mM) were the treatments most effective at inhibiting A. flavus and A. parasiticus population at all a(w) assayed after 11 d of incubation. At all a(w) values, the mixture CA-FA T9 (25 + 30 mM) completely inhibited (100%) aflatoxin B(1) production by both strains at a(w)= 0.99, 0.97, 0.95, and 0.93. Decreased aflatoxin B(1) levels in comparison with the control were observed with mixtures CA-FA T6 (10 + 25 mM), T7 (20 + 20 mM), and T8 (20 + 30 mM) of both strains in the majority of a(w) assayed. The data show that CA and FA could be considered as effective fungitoxicants for A. flavus and A. parasiticus in maize in the a(w) range 0.99 to 0.93. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize.

Interrelation of growth media and water activity in sclerotia characteristics of Aspergillus section Flavi.

AIMS: To examine sclerotium characteristics of two Aspergillus flavus and two A. parasiticus strains at different growth media and water stress. METHODS AND RESULTS: The effects of growth media and water activity (0.999, 0.971, 0.955 and 0.937) on characteristics of sclerotia production (number, size and volume) of four isolates of Aspergillus section Flavi were examined. There was total inhibition under the driest conditions (0.955 and 0.937). When an osmotic potential of 0.971 was generated in Czapek agar (CD) and maize meal extract agar with sucrose and sodium nitrate (MMEA S/N), an increase in sclerotial size and volume was observed. The amount of sclerotia produced by cultures at 0.999 a(w) value was higher on CD. CONCLUSIONS: The data show that the sclerotia characteristics of A. flavus and A. parasiticus have been influenced by water availability and growth media composition. SIGNIFICANCE AND IMPACT OF THE STUDY: The information obtained shows that if we know the nutritional and water stress requirements for sclerotia production, it could be possible to develop effective prevention strategies to inhibit the survival of these fungi in grain.

In vitro studies on the potential for biological control on Aspergillus section Flavi by Kluyveromyces spp.

AIMS: Antagonist activity of Kluyveromyces spp. isolates on Aspergillus section Flavi was studied. METHODS AND RESULTS: The screening of isolates were made through studies of growth at different water activities and temperatures, index of dominance (I(D)), ecological similarity, antifungal activity and impact on aflatoxin B1 accumulation. High optical density was obtained at 25 and 30 degrees C and 48 h of incubation. Cell growth decreases with decrease in water activity. The predominant interaction was mutual intermingling at a(w) = 0.982 and 0.955, while at a(w) = 0.999 and 0.937 mutual inhibition for contact was exhibited. All isolates were catabolically identical to Aspergillus section Flavi and compete by nutritional source. At high water activities yeasts showed inhibitory activity on Aspergillus strains, inhibition percentages varied between 75 and 100%. The isolates Y9, Y14, Y16, Y22, Y25 and Y33 showed antifungal activity and inhibitory activity on aflatoxin B1 accumulation at all water activities assayed from all Aspergillus section Flavi strains. CONCLUSIONS: The data show that the isolates selected in a wide range of environmental conditions could exert their roll like biological control agents for Aspergillus section Flavi in storage maize ecosystem. SIGNIFICANCE AND IMPACT OF THE STUDY: Isolates of Kluyveromyces spp. may have practical value in the postharvest control of storage maize.

Osmotic and matric potential effects on growth, sugar alcohol and sugar accumulation by Aspergillus section Flavi strains from Argentina.

AIMS: The effect of osmotic and matric potential stress on growth and sugar alcohols (polyols: glycerol, erythritol, arabitol and mannitol) and sugars (trehalose and glucose) accumulation in toxigenic and nontoxigenic colonies of Aspergillus flavus and A. parasiticus was evaluated. METHODS AND RESULTS: Growth of Aspergillus section Flavi with significant reductions at 20 and 30 degrees C was more sensitive to changes in matric potential, between 60 and 100% in the range of -7 to -14 MPa. No significant differences were found between toxigenic and nontoxigenic strains for both species. Total polyol accumulation in unamended maize meal agar medium (-0.75 MPa water potential) was higher at 30 than 20 degrees C. The major change in concentrations of endogenous sugars and total polyols was in matrically amended medium (with PEG 8000) at -7 and -10 MPa. Accumulation of glucose, arabitol, mannitol and erythritol content of A. flavus and A. parasiticus mycelial colonies was greater in normal unstressed maize meal agar medium (-0.75 Mpa) at 20 degrees C. This was modified by solute and matric stress. CONCLUSIONS: The data showed relative sensitivity to osmotic and matric potential, and temperature, and the impact on growth rates, polyol and sugar accumulation in mycelia of A. flavus and A. parasiticus. SIGNIFICANCE AND IMPACT OF THE STUDY: The matric potential effects on growth may be of particular importance for growth and survival in environments with low-matric potential stress. The tolerance of spoilage fungi such as Aspergillus section Flavi to such modifications could increase the potential for spoilage and mycotoxin production in such substrates. This knowledge is important for understanding the relative ecological fitness of these aflatoxigenic species and in the development of prevention strategies for their control.

Control of Aspergillus growth and aflatoxin production using antioxidants at different conditions of water activity and pH.

AIMS: The effect of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB) and propyl paraben (PP) (at concentrations of 1, 10 and 20 mmol l(-1)) on germination, growth and aflatoxin B1 production by Aspergillus section Flavi was evaluated. METHODS AND RESULTS: Studies on the percentage of spore germination, elongation rate, growth rate and aflatoxin B1 production were carried out in vitro in relation to water activity (aw) at 0.982, 0.937, 0.809 and 0.747 values. At 0.809 and 0.747aw values none of the isolates was able to germinate. Overall, PP and BHA were the antioxidants most effective at inhibiting germination of both species. In the presence of the lowest concentration of BHA and PP (1 mmol l(-1)) the conidial germination percentage ranged from 2 to 19% after 15 h of incubation at the highest water activity tested. BHA and PP at 10-20 mmol l(-1) completely inhibited conidial germination. The antioxidants more efficient in controlling Aspergillus elongation rate were PP, BHT and BHA. All strains were much more sensitive to all antioxidants tested on the percentage of spore germination and growth rate at 0.937aw. The antioxidants PP and BHA completely inhibited aflatoxin B1 production by all strains when added at 1 mmol l(-1). Decreased aflatoxin B1 levels in comparison with the control, were observed with BHT at 1, 10 and 20 mmol(-1) with the strain T20 at 0.982aw. In contrast, stimulation was observed with the antioxidant THB at 10 and 20 mmol l(-1) at 0.937aw with the strains T20 and T23. The effect of BHA and PP at 1 mmol l(-1) on lag phase and growth rate was maintained in the pH range between 6 and 8. At all pH values the inhibitory effect of BHA was higher than PP. No aflatoxin B1 was detected at all pH values. CONCLUSIONS: The data show that BHA and PP could be considered as effective fungitoxicants for A. flavus and A. parasiticus. SIGNIFICANCE AND IMPACT OF THE STUDY: The information obtained show promise for controlling growth and aflatoxin B1 in stored maize. Futher studies should be carried out to examine the potential for antioxidants, such as BHA and PP to effectively control both growth and aflatoxin production.

Aspergillus section Flavi populations from field maize in Argentina.

AIMS: Populations of Aspergillus section Flavi were studied from a commercial field of maize in Río Cuarto, Córdoba, Argentina. METHODS AND RESULTS: The Aspergillus species were isolated from soil, debris and insects during three periods: pre-planting, growing maize and post-harvest. The colony count from non-rhizospheric soil in the pre-planting period was higher than in growing maize and the post-harvest period. Debris samples analysed during all periods showed similar infection percentages for Aspergillus section Flavi. The samples of insects collected during the maize-growing period showed a lower percentage of Aspergillus isolates than the samples from soil and debris. Aflatoxigenic strains were present in lower levels in each component of the agroecosystem studied. All the strains that produced sclerotia were L strains. CONCLUSIONS: In this field agroecosystem, the only strains with a high probability for transfer to the storage agroecosystem were L strains with low toxigenic potential. SIGNIFICANCE AND IMPACT OF THE STUDY: Maize pre-harvest contamination with aflatoxigenic inoculum was not significant.