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PubMed2002

Protein structure plays a critical role in peanut allergen stability and may determine immunodominant IgE-binding epitopes.

Hypersensitivity to peanuts is a reaction mediated by IgE Abs in response to several peanut protein allergens. Among these allergenic proteins, Ara h 2 is one of the most commonly recognized allergens. Ara h 2 is a 17-kDa protein that has eight cysteine residues that could form up to four disulfide bonds. Circular dichroism studies showed substantial changes in the secondary and tertiary structures of the reduced Ara h 2 as compared with the native protein. Upon treatment with trypsin, chymotrypsin, or pepsin, a number of relatively large fragments are produced that are resistant to further enzymatic digestion. These resistant Ara h 2 peptide fragments contain intact IgE-binding epitopes and several potential enzyme cut sites that are protected from the enzymes by the compact structure of the protein. The enzyme-treated allergen remains essentially intact despite the action of proteases until the fragments are dissociated when the disulfide linkages are reduced. Amino acid sequence analysis of the resistant protein fragments indicates that they contain most of the immunodominant IgE-binding epitopes. These results provide a link between allergen structure and the immunodominant IgE-binding epitopes within a population of food-allergic individuals.

2S Albumins, Plant↗
PubMed1989

Fusarium mycotoxins from peanuts suspected as a cause of sandhill crane mortality.

An estimated 9,500 sandhill cranes (Grus canadensis) died in Gaines County, Texas and Roosevelt County, New Mexico between 1982 and 1987. The predominant clinical sign observed in sick cranes was their inability to hold their heads erect, both while standing and flying. Multiple muscle hemorrhages and submandibular edema were the most common lesions seen at necropsy. Mycotoxins produced by Fusarium sp. growing during cold, wet weather on peanuts left in the field after harvest, the predominant foods of the dead cranes at the time of these mortality events, were identified as the most likely cause of this mortality. Rendering moldy peanuts inaccessible to the cranes by conventional tillage resulted in reduced crane mortality in these areas.

Animals↗
PubMedDate not supplied

Performance of sampling plans to determine aflatoxin in farmers' stock peanut lots by measuring aflatoxin in high-risk-grade components.

Five 2 kg test samples were taken from each of 120 farmers' stock peanut lots contaminated with aflatoxin. Kernels from each 2 kg sample were divided into the following U.S. Department of Agriculture grade components: sound mature kernels plus sound splits (SMKSS), other kernels (OK), loose shelled kernels (LSK), and damaged kernels (DAM). The kernel mass (g), aflatoxin mass (ng), and aflatoxin concentration (ng of aflatoxin/g of peanuts) were measured for each of the 2400 component samples. The variabilities associated with measuring aflatoxin mass (ng) in OK + LSK + DAM, or A(OLD)ng, and in LSK + DAM, or A(LD)ng, and aflatoxin concentration (ng/g) in OK + LSK + DAM, or A(OLD)ng/g, and in LSK + DAM, or A(LD)ng/g, were determined. The variance associated with measuring aflatoxin in each of the 4 combinations of components increased with aflatoxin, and functional relationships were developed from regression analysis. The variability associated with estimating the lot concentration from each of the 4 combinations of components was also determined. The coefficients of variation (CV) associated with estimating the aflatoxin for a lot with aflatoxin at 100 ng/g were 90, 86, 94 and 96% for aflatoxin masses A(OLD)ng and A(LD)ng and aflatoxin concentrations A(OLD)ng/g and A(LD)ng/g, respectively. The performance of aflatoxin sampling plans using the combination of aflatoxin masses in OK + LD + DAM and LD + DAM components was evaluated with a 2 kg test sample and a 50 ng/g accept/reject limit.

Aflatoxins↗
PubMedDate not supplied

Determination of aflatoxins in grains and raw peanuts by a rapid procedure with fluorometric analysis.

A rapid, quantitative, inexpensive, and efficient method was developed to determine aflatoxins in corn, corn meal, popcorn, rice, wheat, cottonseed, and peanuts. Samples are ground and extracted with methanol-water (80 + 20). A portion of the extract is cleaned up by passage through a solid-phase separatory column, 500 microL purified extract is derivatized with a bromine reagent, and fluorescence of the solution is immediately quantified with a calibrated fluorometer containing a broad wavelength pulsed xenon light source. This method can quantify aflatoxin from 5 to 5000 ppb without dilution and was linear when applied to samples of noncontaminated corn spiked at 0 to 5000 micrograms aflatoxin B1/g. Correlation coefficients of the method with LC for multiple analyses for corn (n = 34), cottonseed (n = 32), and peanuts (n = 11) were 0.999, 0.995, and 0.980, respectively. Individual analyses may be conducted in less than 5 min, and grouping of samples is unnecessary. The sensitivity of the method for corn is 5 ppb and the fluorometer, under the operating conditions, has a limit of detection of 0.6 ng aflatoxin B1.

Aflatoxin B1↗
PubMedDate not supplied

Immunoaffinity column cleanup with liquid chromatography using post-column bromination for determination of aflatoxins in peanut butter, pistachio paste, fig paste, and paprika powder: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 and total aflatoxins at European regulatory limits. The test portion is extracted with methanol-water (8 + 2) for dried figs and paprika, and with methanol-water (8 + 2) plus hexane (or cyclohexane) for peanut butter and pistachios. The sample extract is filtered, diluted with phosphate buffer saline, and applied to an immunoaffinity column. The column is washed with water and the aflatoxins are eluted with methanol. Aflatoxins are quantitated by reversed-phase LC with post-column derivatization (PCD) involving bromination. PCD is achieved with either an electrochemical cell (Kobra cell) and addition of bromide to the mobile phase or pyridinium hydrobromide perbromide. Determination is by fluorescence. Peanut butter, pistachio paste, dried fig paste, and paprika powder samples, both naturally contaminated with aflatoxins and containing added aflatoxins, were sent to 16 collaborators in 16 European countries. Test portions of samples were spiked at levels of 2.4 and 9.6 ng/g for total aflatoxins which included 1.0 and 4.0 ng/g aflatoxin B1, respectively. Recoveries for total aflatoxins ranged from 71 to 92% with corresponding recoveries for aflatoxin B1 of 82 to 109%. Based on results for spiked samples (blind duplicates at 2 levels) as well as naturally contaminated samples (blind duplicates at 4 levels, including blank), the relative standard deviation for repeatability ranged from 4.6 to 23.3% for total aflatoxins and from 3.1 to 20.0% for aflatoxin B1. The relative standard deviation for reproducibility ranged from 14.1 to 34.2% for total aflatoxins, and from 9.1 to 32.2% for aflatoxin B1. The method showed acceptable within-laboratory and between-laboratory precision for all 4 matrixes, as evidenced by HORRAT values <1, at the low levels of determination for both total aflatoxins and aflatoxin B1.

Aflatoxin B1↗
PubMed2000

Educational program for children with peanut allergy.

The best approach to managing peanut allergy is to educate patient and family. We developed specific consultation for children with peanut allergy. We follow a structurized program in a pedagogical manner. The objectives of this program are to encourage appropriate understanding, recognition of the signs of allergy, and if it is necessary, to teach how to inject oneself with an epinephrine injection. The aim of these sessions is to improve knowledge on basic allergy, recognition of hidden foods, on reading labelling, on recognition of earliest signs and finally on use of epinephrine as a rescue treatment. Behaviour in restaurant and most of all at school is also precised. The interview began with the parents and children, followed by discussions and pedagogical games. Our subjects experiences, described below, suggest that these educational programs are beneficial. As the others chronic pathologies, patients with this program seem to have less allergic reactions, and are able to respond with the appropriate behaviour when symptoms appear. Three months later, we conduct the efficiency of the treaning.

Adolescent↗
PubMed2000

Growth, pod, and seed yield, and gas exchange of hydroponically grown peanut in response to CO2 enrichment.

The effects of elevated CO2 on growth, pod, and seed yield, and gas exchange of 'Georgia Red' peanut (Arachis hypogaea L.) were evaluated under controlled environmental conditions. Plants were exposed to concentrations of 400 (ambient), 800, and 1200 micromoles mol-1 CO2 in reach-in growth chambers. Foliage fresh and dry weights increased with increased CO2 up to 800 micromoles mol-1, but declined at 1200 micromoles mol-1. The number and the fresh and dry weights of pods also increased with increasing CO2 concentration. However, the yield of immature pods was not significantly influenced by increased CO2. Total seed yield increased 33% from ambient to 800 micromoles mol-1 CO2, and 4% from 800 to 1200 micromoles mol-1 CO2. Harvest index increased with increasing CO2. Branch length increased while specific leaf area decreased linearly as CO2 increased from ambient to 1200 micromoles mol-1. Net photosynthetic rate was highest among plants grown at 800 micromoles mol-1. Stomatal conductance decreased with increased CO2. Carboxylation efficiency was similar among plants grown at 400 and 800 micromoles mol-1 and decreased at 1200 micromoles mol-1 CO2. These results suggest that CO2 enrichment from 400 to 800 micromoles mol-1 had positive effects on peanut growth and yield, but above 800 micromoles mol-1 enrichment seed yield increased only marginally.

Arachis↗
PubMed2000

[Determination of aflatoxins in peanut by high performance liquid chromatography using immunoaffinity column clean-up and on-line electrochemical derivatization].

A method for the determination of aflatoxin B1, B2, G1 and G2 in peanut by high performance liquid chromatography using immunoaffinity column clean-up and on-line electrochemical derivatization was developed. Sample was extracted with 80% methanol and the extract was passed through the IAC. Aflatoxins were retained by the monoclonal in the IAC and eluted with actonitrile. AFT B1 and G1 were derivatized with on-line electrochemical equipment Kobra Cell. The four toxins can be separated in 13 minutes and the detection limit was 0.1 microgram/kg for each toxin. The method has been applied to the determination of peanut sample. The relative standard deviation was 9.2%-15% and the average recovery of AFT spiked at 0.5-9.0 micrograms/kg levels was in the range of 74.8%-97.3%.

Aflatoxin B1↗
PubMed1999

[The use of AFLP technique for the study of genetic diversity in peanut bradyrhizobia].

A total of 146 bradyrhizobial strains including 133 peanut bradyrhizobia isolated from different regions and 13 reference strains representing B. japonicum and B. elkanii were studied for their genetic diversity by use of AFLP marker technique. The genomic similarity was analysed by numerical Taxonomy based on the AFLP patterns. The results showed that the genetic diversity of peanut bradyrhizbia were very high. Each strain had a identical AFLP pattern. AFLP technique is simple, fast, highly reproducible, and is a useful tool for evaluating genetic diversity.

Arachis↗
PubMed2003

Peanut allergy: an overview.

Peanut allergy accounts for the majority of severe food-related allergic reactions. It tends to present early in life, and affected individuals generally do not outgrow it. In highly sensitized people, trace quantities can induce an allergic reaction. In this review, we will discuss the prevalence, clinical characteristics, diagnosis, natural history and management of peanut allergy.

Arachis↗
PubMed2003

Immunochemical and biological quantification of peanut extract.

Biological standardization of allergen extracts is one of the steps in the characterization of an extract. The gold standard for determination of biological potency is the skin prick test, but histamine release (HR) has been used as a convenient ex vivo method for analyzing a large number of samples. We describe the use of rabbit basophils as a tool in biological standardization. Using peanut as a model allergen, it is described how rabbits immunized for production of antiserum may become sensitized and their basophils used for histamine release experiments. It is also possible to use rabbit antiserum to passively sensitize basophils derived from naive rabbits, but the sensitivity of this method is so far 100-1000 times lower than the direct histamine release. The rabbit histamine release results are compared to an ELISA developed by means of the same antisera and by passive sensitization of human basophils using serum from a strongly sensitized peanut-allergic patient. The overall sensitivity of the methods were ELISA > HR-human cells > HR-sensitized rabbit cells > HR-passively sensitized rabbit cells. The use of rabbit basophils for biological standardizations will allow for the use of rabbit antisera.

Animals↗
PubMed2004

[Utilization of powdered peanut hull as biosorbent for removal of anionic dyes from aqueous solution].

An untried, low cost, locally available biosorbent for its anionic dye removal capacity from aqueous solution was investigated. Powder prepared from peanut hull had been used for biosorption of three anionic dyes, amaranth (Am), sunset yellow (SY) and fast green FCF (FG). The effects of various experimental parameters (e.g. initial pH and dye concentration, sorbent dosage, particle size, ion strength, contact time etc.) were examined and optimal experimental conditions were decided. At initial pH 2.0, three dyes studied could be removed effectively. When the dye concentration was 50 mg x L(-1), the percentages of dyes sorbed was 95.5% in Am, 91.3% in SY and 94.98% in FG, respectively. The ratios of dyes sorbed had neared maximum values in all three dyes when sorbent dose of 5.0 g x L(-1) and the sorbent particle size in 80-100 mesh was used. The increasing the ion strength of solution caused the decrease in biosorption percentages of dyes. The equilibrium values arrived at about 36 hour for all three dyes. The isothermal data of biosorption followed the Langmuir and Freundlich models. The biosorption processes conformed the pseudo-first-order rate kinetics. The results indicated that powdered peanut hull was an attractive candidate for removing anionic dyes from dye wastewater.

Adsorption↗
PubMedDate not supplied

Validation of two commercial lateral flow devices for the detection of peanut proteins in cookies: interlaboratory study.

Results are reported for an interlaboratory validation study of 2 commercially available Iateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 0-30 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing < 21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (> or = 5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

Arachis↗
PubMedDate not supplied

Comparison of two ELISA screening tests with liquid chromatography for determination of aflatoxins in raw peanuts.

A study was conducted to evaluate the performance of 2 enzyme-linked immunosorbent assays (ELISA) for rapidly screening samples of peanuts for the presence of aflatoxin. The EZ-Screen Quick Card Test and the Afla-10 Cup Test were compared with liquid chromatography in duplicate analyses of common extracts of peanuts contaminated in the range of 0-70 ppb (ng/g). Each assay properly identified 95% of samples containing no detectable aflatoxin as negative and greater than 97% of samples containing greater than 10 ppb aflatoxin as positive. The card test, which had a 20 ppb detection threshold, identified as positive 32 of 34 samples in the 11-20 ppb range. This indicates that the card test might actually have a detection threshold closer to 10 ppb. Most of the errors associated with the assays occurred on samples containing less than 10 ppb aflatoxin. The cup and card tests identified 76 and 67% of the samples, respectively, as negative, in the range of 4-10 ppb. For samples either negative or contaminated above their detection thresholds for the assays, the methods are well suited for use as rapid screening tests.

Aflatoxins↗
PubMedDate not supplied

Simulation of aflatoxin testing plans for shelled peanuts in the United States and in the export market.

The 1987 United States aflatoxin testing plan for shelled peanuts was designed with a final accept level of 25 parts per billion (ppb) total aflatoxin. Some of the importers of U.S. peanuts use aflatoxin testing plans with accept levels lower than 25 ppb. For example, the accept level of a testing plan used in The Netherlands is 5 ppb B1 or 10 ppb total aflatoxin. Whenever export lots are re-tested for aflatoxin by an importing country, some lots accepted in the United States will be rejected by the importing country's aflatoxin testing plan. Computer models were developed to determine the effects of decreasing the final accept level of the U.S. testing plan on the number of lots accepted and rejected in the United States and the number of exported lots accepted and rejected by The Netherlands testing plan. Decreasing the final accept level of the U.S. testing plan from 25 to 5 ppb increased the number of lots rejected in the United States by 371% while reducing the number of exported lots rejected by 51%. For every additional 8.3 lots rejected in the United States, one less export lot will be rejected.

Aflatoxins↗
PubMed1986

Investigation of aflatoxin contamination in commercial Spanish peanuts.

In the present study aflatoxin contamination was investigated with 102 peanut samples. Only 11 samples showed contamination by that mycotoxin. Concentration was less than 15-20 micrograms/kg in all the contaminated samples. Aflatoxin B1, B2, G1, and G2 were detected in the above-mentioned samples. No significant difference was found between shell and shelled peanuts owing to aflatoxin contamination.

Aflatoxin B1↗
PubMedDate not supplied

Rapid determination of aflatoxins in raw peanuts by liquid chromatography with postcolumn iodination and modified minicolumn cleanup.

A method is described for rapid cleanup followed by reverse-phase liquid chromatographic (LC) quantitation of aflatoxins in raw peanuts. A modified minicolumn cleanup is used for sample preparation, and a preliminary estimation of aflatoxin content by minicolumn can be made so that highly contaminated samples can be diluted before LC analysis. The use of the simple, quick minicolumn cleanup eliminates the need for further column or cartridge cleanup, thus greatly reducing sample preparation time. Sensitive quantitation is achieved using a phenyl column, a mobile phase of water-tetrahydrofuran (80 + 20, v/v), and postcolumn derivatization with water-saturated iodine followed by fluorescence detection. The recoveries of aflatoxins B1, B2, G1, and G2 from peanut meal spiked at 3 levels ranged from 71.7 to 88.3% (average 80%) with coefficients of variation from 2.7 to 10.4%.

Aflatoxins↗
PubMed1986

Bovine abortion and death associated with consumption of aflatoxin-contaminated peanuts.

Approximately 12% of a herd of 68 crossbred cows aborted third-trimester fetuses after consuming moldy peanuts for 4 days. Further investigation revealed that less than 20% of the herd had access to this supplemental feed. Results of serum biochemical analysis indicated liver damage in the affected cows. All of these cows died within 8 days of aborting. The peanuts contained 77 micrograms aflatoxin B1/g, as determined by liquid chromatography. Tissues were submitted from 1 cow, and liver contained 5 ng aflatoxin B1/g. Results of other laboratory tests were negative for common toxins and abortifacients.

Abortion, Veterinary↗