Biomedical subjects

A Visconti

Publications and source records attributed to A Visconti.

At least 19 recordsLinked to original sources

PubMed2006

Single-ion dosemeter based on floating gate memories.

Floating Gate (FG) nonvolatile memories are based on a tiny polysilicon layer (the FG) which can be permanently charged with electrons or holes, thus changing the threshold voltage of a MOSFET. Every time a FG is hit by a high energy ion, it experiences a charge loss, depending on the ion linear energy transfer (LET) and on the transistor geometrical and electrical characteristics. This paper discusses the opportunities to use this devices as single an ion dosemeter with sub-micrometer spatial resolution and capable of distinguish the impinging ion LET.

Computer Storage Devices↗

PubMed2006

Effect of Lobesia botrana damages on black aspergilli rot and ochratoxin A content in grapes.

Sixty-nine wine grape samples of two varieties (Bombino Nero and Uva di Troia) were collected from four vineyards in a high ochratoxin A (OTA) incidence grape-growing area in Apulia, southern Italy, during the 2001 and 2002 crop harvests. The levels of toxin, measured in the two year harvests, ranged from 0.02 to 681 ng/g of fresh berries. In both surveys, higher levels of contamination by black aspergilli and OTA were found in both intact and rotten berries originating from bunches damaged by Lobesia botrana larvae as compared to bunches without L. botrana attacks. All berry samples with an OTA level >1 ng/g were contaminated by black aspergilli with a CFU>10(6), and all but one of these samples belonged to the Lobesia damaged berries group. This is the first evidence of an interaction between L. botrana damaged berries and OTA contamination, in field.

Animals↗

PubMed2006

Development of a quantitative real-time PCR assay for the detection of Aspergillus carbonarius in grapes.

Aspergillus carbonarius is the main species responsible for the production of ochratoxin A (OTA) in wine grapes. To monitor and quantify A. carbonarious in grapes, a quantitative real-time PCR assay was developed as a possible tool for predicting the potential ochratoxigenic risk. DNA extraction from grape berries was performed by using conventional extraction and clean up through EZNA Hi-bond spin columns. A TaqMan probe was used to quantify A. carbonarius genomic DNA in grape berries samples. An exogenous internal positive control was used to overcome DNA recovery losses due to matrix inhibition. The quantification of fungal genomic DNA in naturally contaminated grape was performed using the TaqMan signal versus spectrophotometrically measured DNA quantities (Log10) calibration curve with a linearity range from 50 to 5 x 10(-4) ng of DNA. A positive correlation (R2=0.92) was found between A. carbonarious DNA content and OTA concentration in naturally contaminated grape samples. This is the first application of TaqMan real-time PCR for identifying and quantifying A. carbonarius genomic DNA occurring in grapes. The rapid DNA extraction method for grapes, together with the commercial availability of reagents and instrumentation, allows to perform a remarkable number of reproducible assays (96-well format) in less than 4 h.

Aspergillus↗

PubMed2006

Multiple sclerosis: pharmacogenomics and personalised drug treatment.

Multiple sclerosis (MS) is a disorder of the central nervous system with an inflammatory and a neurodegenerative component. We do not yet have a definitive therapy for MS. Attempts to develop new treatments are long and costly and should be paralleled by studies aimed at increasing the therapeutic index of the existing treatments, interferon beta and glatiramer acetate. Pharmacogenetics and pharmacogenomics may be of use in this respect though their application may not be straightforward, particularly in MS.

Humans↗

PubMed2006

An electrochemical bioassay for dichlorvos analysis in durum wheat samples.

The use of an acetylcholinesterase inhibition assay for the detection of dichlorvos in durum wheat samples by a simplified extraction procedure is reported. After an incubation step, the residual activity was determined with an amperometric biosensor using a portable potentiostat. The use of electric eel and recombinant acetylcholinesterase was compared. The effect of the matrix extract was evaluated by using various sample:solvent ratios, 1:2.5, 1:5, 1:10, and 1:20. The optimal extraction ratio, considering the electrochemical interferences and the effect on enzyme activity and bioavailability of the pesticide, was 1:10. Calibrations were performed in buffer and durum wheat extract. The calculated detection limits in buffer solution were 10 ng/ ml and 0.045 ng/ml for electric eel and recombinant acetylcholinesterase, respectively, whereas operating in the matrix extract they increased up to 45 ng/ml and 0.07 ng/ml, corresponding to 0.45 mg/kg (extraction ratio 1:10) and 0.07 mg/kg in samples. These characteristics allowed the detection of contaminated samples at the maximum residue limit, which is 2 mg/kg and well below. Fortified samples of durum wheat were obtained with both dichlorvos and the commercial product Didivane, which contains dichlorvos as an active molecule. At all the tested levels, the occurrence of contaminant was detected with an average recovery of 75%. The total assay time, including the extraction step, was 30 min. Because several extractions as well as most of the assay steps can be run simultaneously, the throughput for one operator is 12 determinations per hour.

Acetylcholinesterase↗

PubMed2005

Persistence of fenitrothion in oranges and clementines after treatment with emulsifiable concentrate and microencapsulate formulations.

The rate of decline of fenitrothion residues was investigated in oranges and clementines after treatment with two different kinds of commercial formulations: emulsifiable concentrate (Afidina M) and microencapsulate (Fenitrocap and IPM 400). The study was performed on the fruit and leaves over 131 and 161 days for oranges, and over 78 and 86 days for clementines, respectively. In fruit, the experimental data showed a similar behaviour of the active ingredient for both kinds of commercial formulations. High mean levels of fenitrothion (between about 0.4 and 0.8 mg kg(-1)) were persistent for at least 75 days after treatment in oranges and 50 days in clementines, with statistically significant declines observed only at days 110 and 78, respectively. A rapid decline of fenitrothion levels was observed in orange and clementine leaves during the starting phase followed by a slower decrease during the later stage; the decline was more pronounced with the treatment of emulsifiable concentrates. These findings are indicative of a poor degradability of fenitrothion in citrus fruits, and suggest that repeated or uneven applications of the pesticide should be avoided in order to exclude the risk of exceeding the maximum residue level permitted by the current regulations.

Citrus↗

PubMed2005

Recent advances on the use of adsorbent materials for detoxification of Fusarium mycotoxins.

The extensive use of adsorbents in the livestock industry has led to the introduction of a wide range of new products on the market, most of them claiming high in vitro mycotoxin adsorption capacity. However, adsorbents that may appear effective in vitro do not necessarily retain their efficacy when tested in vivo. Studies performed in our laboratory during the past few years aiming to evaluate the efficacy of various adsorbent materials in binding Fusarium mycotoxins are reported. Adsorption experiments were performed in in vitro screening tests for Fusarium mycotoxins at different pHs; by in vivo tests using the increase of the sphinganine to sphingosine ratio in rat urine and tissues as a biomarker of fumonisin exposure; and by a dynamic, computer-controlled, gastrointestinal model simulating the gastrointestinal tract of healthy pigs. Most of the commercially available mycotoxin-binders failed in sequestering in vitro Fusarium mycotoxins. Only for a small number of adsorbent materials was the ability to bind more than one mycotoxin demonstrated. Cholestyramine was proven to be an effective binder for fumonisins and zearalenone in vitro, which was confirmed for zearalenone in experiments using a dynamic gastrointestinal model and for fumonisins in in vivo experiments. No adsorbent materials, with the exception of activated carbon, showed relevant ability in binding deoxynivalenol and nivalenol. The in vitro efficacy of activated carbon toward fumonisins was not confirmed in vivo by the biomarker assay. The dynamic gastrointestinal model was a reliable tool to study the effectiveness of adsorbent materials in reducing the bioaccessibility of Fusarium mycotoxins, as an alternative to the more difficult and time-consuming studies with domestic livestock.

Adsorption↗

PubMed2005

Assessment of trichothecene chemotypes of Fusarium culmorum occurring in Europe.

Fusarium trichothecenes are a group of fungal toxic metabolites whose synthesis requires the action of gene products from three different genetic loci. We evaluated, both chemically and by PCR assays, 55 isolates of Fusarium culmorum from eight European countries and different host plants for their ability to produce trichothecenes. Specific sequences in the Tri6-Tri5 intergenic region were associated with deoxynivalenol production. Sequences in the Tri3 gene were also associated with deoxynivalenol production and specific primer sets were selected from these sequences to identify 3-acetyl-deoxynivalenol or 15-acetyl-deoxynivalenol chemotypes. Specific sequences in the Tri5 and Tri7 genes were associated with the nivalenol chemotype but not with the deoxynivalenol chemotype. Two chemotypes were identified by chemical analysis and confirmed by PCR. Strains of the nivalenol chemotype produced nivalenol (up to 260 microg g(-1)) and 4-acetyl-nivalenol (up to 60 microg g(-1)), strains with the 3-acetyl-deoxynivalenol chemotype produced deoxynivalenol (up to 1700 microg g(-1)) and 3-acetyl-deoxynivalenol (up to 600 microg g(-1)). Three strains of F. culmorum from France, previously reported as 15-acetyl-deoxynivalenol producers, had the 3-acetyl-deoxynivalenol chemotype. The results are consistent with data from other European countries on the occurrence of the nivalenol and 3-acetyl-deoxynivalenol chemotypes and provide support for the hypothesis that European isolates of F. culmorum producing deoxynivalenol belong only to the 3-acetyl-deoxynivalenol chemotype. The production of trichothecenes from F. culmorum isolates from walnut (3-acetyl-deoxynivalenol chemotype) and leek (nivalenol chemotype) is reported for the first time.

DNA, Fungal↗

PubMed2005

Occurrence of patulin in conventional and organic fruit products in Italy and subsequent exposure assessment.

The occurrence of patulin was investigated in 100 conventional and 69 organic fruity foodstuffs samples commercially available in Italy by using an HPLC method with a limit of quantification of 0.5 microg kg(-1). Patulin was detected in 26 (26%) conventional and 31 (45%) organic products with a significantly higher (p<0.01) mean concentration in the organic products (4.78 vs. 1.15 microg kg(-1)). Mean patulin concentrations in conventional apple juices, pear juices, other juices and fruits purees were 3.14, 0.22, 0.19, 0.11 microg kg(-1), respectively, and 7.11, 11.46, 2.10, 0.18 microg kg(-1) in the relevant organic products. Four samples of juices (one conventional and two organic apple, and one organic pear) contained patulin at concentrations above the limit of 50 microg kg(-1), four at concentrations between 10 and 25 microg kg(-1), and the remaining ones below 10 microg kg(-1). Patulin was detected (<1 microg kg(-1)) in only three of the 23 fruity baby food samples tested (homogenized fruits, 11 conventional and 12 organic). Based on the available data on Italian intakes of fruit juices, the estimated daily intakes of patulin, were 0.38 and 1.57 ng kg(-1) body weight (bw) from conventional and organic products, respectively. Estimated daily intakes of patulin for children were higher, 3.41 ng kg(-1) bw from conventional and 14.17 ng kg(-1) bw from organic products, but largely below the provisional maximum tolerable daily intake (PMTDI) of 400 ng kg(-1) bw. Patulin was also found in two samples of organic apple vinegar (<5 microg kg(-1)) and in fresh apples with rotten spots (12 out of 24 samples) with maximum levels at 16,402 and 44,572 microg kg(-1) for conventional and organic apples, respectively.

Beverages↗

PubMed2005

Fitness for purpose--ochratoxin A analytical developments.

Laboratory accreditation involving third party auditing, the use of validated methods and participation in laboratory proficiency testing are essential elements for laboratory quality assurance in relation to ochratoxin A (OTA) analysis. A number of methods, mainly based on liquid chromatography (LC) with fluorescence detection (FD), coupled with immunoaffinity column or solid phase extraction cleanup, have been collaboratively validated and adopted as official standards for OTA determination in a variety of foods, including cereals, coffee, wine and beer. Enzyme-linked immunosorbent assays (ELISA) kits are widely used as screening methods for the occurrence of OTA in food. Novel technologies using anti-OTA antibodies (electrochemical immunosensors, fluorescence polarisation, lateral flow devices, enzyme-based flow through membranes, and surface plasmon resonance biosensors) have been proposed for rapid analysis of OTA in food and beverages, and may be applied for in situ measurements. Validation of these immunochemical methods and commercial kits is required. Liquid chromatography-mass spectrometry represents an adequate alternative to LC-FD particularly in the area of multi-mycotoxin analysis. OTA specific molecularly imprinted polymers are currently considered for cleanup as a potential and cheaper alternative to immunoaffinity or solid-phase extraction sorbents.

Carcinogens↗

PubMed2004

Comparison of urinary sphingolipids in human populations with high and low maize consumption as a possible biomarker of fumonisin dietary exposure.

The increased sphinganine/sphingosine (SA/SO) ratio has previously been shown as a biomarker of fumonisin exposure in experimental animals and has been proposed as a tool to assess human exposure to fumonisin mainly occurring through the dietary consumption of fumonisin contaminated maize-based foods. Sphinganine and sphingosine were measured in urines of humans resident in two areas of North Argentina and South Brazil with high maize consumption and compared with urine samples collected in areas with very low or no maize consumption, such as Central Argentina and Southern Italy. The pattern of SA/SO values in the two groups with no maize consumption (assumed as controls) was similar, with all SA/SO values lower than one. Mean SA/SO ratio was 1.27 in urine of subjects with high maize consumption (n = 123) and 0.36 in controls (n = 66) and the difference was statistically significant (p<0.001). The mean fumonisin level in maize samples collected in North Argentina and South Brazil was 0.35 mg kg(-1) (n = 40). Although a similar maize and fumonisin intake was recorded for the two groups of populations, the mean SA/SO ratio in South Brazil (1.57) was significantly higher (p<0.05) than that of North Argentina (0.69). These data suggest that the higher SA/SO values observed in South Brazil cannot be associated with high fumonisin exposure and further studies are necessary to provide convincing evidence for using the SA/SO ratio as a biomarker of human fumonisin exposure.

Adolescent↗

PubMed2003

Physiopathology of multiple sclerosis.

Pleiotropy and redundancy are distinctive elements of the immune response. Recent research into the inflammatory component of multiple sclerosis (MS) indicates that, as expected, pleiotropy and redundancy characterize various physiopathological mechanisms of the disease. A certain degree of redundancy is becoming apparent also as far as the degenerative component is concerned. Cumulatively, these data suggest that treatments that target single pathogenetic pathways are unlikely to provide a definitive solution. Combination therapies may offer, in principle, some advantage, although there is a need for more information on the aetiology of the disease.

Animals↗

PubMed2002

Amino-bonded silica as stationary phase for liquid chromatographic determination of cyclopiazonic acid in fungal extracts.

A new high-performance liquid (HPLC) chromatographic method is described for cyclopiazonic acid (CPA) determination in fungal cultures on a propylamino-bonded stationary phase with a CH3CN/CH3COONH4 buffer as mobile phase. Retention of CPA on propylamino modified silica under acidic conditions (protonated amino groups and deprotonated CPA) is governed by a mixed ion-exchange-reversed-phase mechanism. In addition to non-polar (hydrophobic) interactions, polar interactions with the surface silanols are also possible and become important as the polarity of the mobile phase decreases. A detection limit of 25 pg of CPA standard is obtained that represents an improvement of more than two orders of magnitude compared to existing HPLC procedures. UV-detector response was linear to 200 ng of CPA. Fungal extracts can be analysed after a simple dilution step with UV diode array detection that provides peak identity/purity assessment. The suitability of the proposed method as a rapid confirmatory test to assess the toxigenic potential of different Aspergillus and Penicillium strains is demonstrated by the analysis of 54 fungal extracts.

Amines↗

PubMed2001

Survey on mycoflora of cow and buffalo dairy products from Southern Italy.

Economic losses of dairy products due to spoilage by yeasts have been increasing in European companies because of the reduced use of preservatives, packaging in modified atmospheres, or new formulations that do not strictly control the growth of these organisms. This study reports the results of a survey of yeast species and populations in 145 samples of cow and buffalo dairy products collected in some regions of Southern Italy. Yeasts were isolated from 74% and 57% of cow and buffalo products, respectively. Candida inconspicua was the predominant species in unripened products from cow's milk, while C. famata was detected in medium and long-term ripened dairy products, mostly in association with other yeasts and with moulds belonging to the genus Penicillium. For dairy products produced from buffalo milk, C. inconspicua was the most important yeast frequently isolated from dairy products. Total yeast populations ranged from 5 x 10(2) to 5 x 10(5) cfu/g, indicating a good hygienic quality of the products. The isolation of C. albicans from one stracciatella sample is noteworthy, as this yeast represents a potential contamination by human. Even though yeasts are considered as environmental contaminants, the occurrence of some of them in dairy products at high levels could represent a risk for human health, in particular for immunocompromised patients.

Animals↗

PubMed2001

Ineffectiveness of activated carbon in reducing the alteration of sphingolipid metabolism in rats exposed to fumonisin-contaminated diets.

Sphinganine/sphingosine (SA/SO) ratio, a biomarker of fumonisin exposure, has been measured in urine, kidney and liver of male Wistar rats exposed to fumonisin-contaminated diet with and without the addition of activated carbon (AC). The latter was previously shown to adsorb fumonisin B(1) in vitro. Rats were fed either control diet or fumonisin-contaminated diet (4 microg FB(1+)FB(2)/g) or fumonisin-contaminated diet mixed with 20 mg AC/g diet for 1 week. In rats fed fumonisin-contaminated diet, the SA concentration and SA/SO ratio increased significantly and reversibly in kidney, while urine and liver did not show a significant increase of SA/SO ratio. The addition of AC to the fumonisin-contaminated diet did not alter the change of SA/SO biomarker for fumonisin exposure. This provides indications that the use of AC to reduce the toxicity of fumonisins is unlikely to be effective in vivo.

Animal Feed↗

PubMed2001

Rapid method for the determination of ochratoxin A in urine by immunoaffinity column clean-up and high-performance liquid chromatography.

A rapid and accurate method to quantify ochratoxin A (OTA) at ppt (pg/ml) levels in urine has been developed. The method uses commercial immunoaffinity columns for clean-up and reversed phase high-performance liquid chromatography (HPLC) with fluorescence detector for quantification of the toxin. Average recoveries of OTA from human urine spiked at levels from 0.05 ng/ml to 1.0 ng/ml ranged from 88% to 93%, with relative standard deviations (RSDs) between 1% and 8%. Detection limit was 0.005 ng/ml. Out of 41 human urine samples, 25 were found positive to OTA with only one sample exceeding 0.05 ng/ml; the latter originated from a patient affected by karyomegalic interstitial nephritis. The method can be used as a rapid and non-invasive tool to assess human and animal exposure to OTA in epidemiological studies and to establish the possible role of OTA in acute animal intoxications or human end-stage renal diseases.

Animals↗

PubMed2001

In vitro and in vivo studies to assess the effectiveness of cholestyramine as a binding agent for fumonisins.

Several adsorbent materials were tested at I mg/ml for their in vitro capacity to adsorb fumonisin B1(FB1) from aqueous solutions. Cholestyramine showed the best adsorption capacity (85% from a solution containing 200 microg/ml FB1) followed by activated carbon (62% FB1). Bentonite adsorbed only 12% of the toxin from a solution containing 13 microg/ml FB1, while celite was not effective even at the lowest tested FB1 concentration (3.2 microg/ml). Cholestyramine was tested in vivo to evaluate its capacity to reduce the bioavailability of fumonisins (FBs) in rats fed diet contaminated with toxigenic Fusarium verticillioides culture material. Rats were exposed for one week to FBs-free diet, FBs-contaminated diet containing 6 or 20 microg/g FB1 + FB2 and the same FBs-contaminated diet added of 20 mg/g cholestyramine. The increase of sphinganine/sphingosine (SA/SO) ratio in urine and kidney of treated rats was used as specific and sensitive biomarker of fumonisin exposure. The addition of cholestyramine to the FBs-contaminated diets consistently reduced the effect of FBs by reducing significantly (P < 0.05) both urinary and renal SA/SO ratios.

Animals↗

PubMed2001

Comparison of different extraction and clean-up procedures for the determination of fumonisins in maize and maize-based food products.

In order to optimize the analytical method for the determination of fumonisin B1 (FB1) and fumonisin B2 (FB2) in different maize products, five materials (maize flour, corn flakes, extruded maize, muffins and infant formula) were investigated under a variety of experimental conditions organized in a ruggedness test according to a factorial design. The influence of five factors (extraction solvent, extraction mode, volume of extraction solvent, test sample size and clean-up) on method performances was tested by four laboratories using spiked materials (0.5 microgram/g and 1.5 micrograms/g FB1 + FB2) and naturally contaminated materials (ca 1.5 micrograms/g with FB1 + FB2). The end determination step was performed by high-performance liquid chromatography analysis of the o-phthaldialdehyde derivatized extracts. The ruggedness test permitted identification of two critical factors in the analysis of fumonisins in the above products, namely 'extraction solvent' and 'clean-up procedure'. In particular, the use of acetonitrile (ACN)-water (1 + 1, v + v) as extraction solvent and immunoaffinity column for clean-up provided better recovery of fumonisins and chromatographic resolution as compared with methanol (MeOH)-water (3 + 1, v + v) and strong anion exchange (SAX), respectively. However, phase separation occurring after extraction with ACN-water may have given incorrect results. Based on the information obtained with the present study it was possible to develop a new method horizontally applicable to all the above mentioned maize-based food matrices.

Carboxylic Acids↗