Evaluation of an enzyme immunoassay for the detection of the mycotoxin tenuazonic acid in sorghum grains and sorghum-based infant food

An enzyme-linked immunosorbent assay (ELISA) for the Alternaria mycotoxin tenuazonic acid (TeA) was evaluated by comparative analysis of naturally contaminated sorghum grains and sorghum-based infant food, using a stable isotope dilution LC-MS assay (SIDA; limit of detection (LOD) 1.0 μg/kg) as the reference method. LODs of the ELISA were 30 μg/kg in sorghum grains and 220 μg/kg in sorghum-based infant cereals. With SIDA, 100% of the samples (n = 28) had been positive for TeA in a concentration range of 6–584 μg/kg (mean 113 μg/kg). The ELISA consistently detected TeA in all naturally contaminated samples at cut-off levels of 30–60 μg/kg (sorghum) and 200–300 μg/kg (infant cereals), as based on corresponding to SIDA values. Although the ELISA was much less sensitive than the SIDA method, it may be useful as a screening method for sorghum and sorghum-based infant foods and can be employed to identify samples containing elevated concentrations of TeA in food, well below the proposed level of concern (500 μg/kg).     

Do attitudes expressed in surveys predict ethnic discrimination?

Survey data on people’s reported attitudes towards ethnic minorities are sometimes used as a proxy for ethnic discrimination. However, there is weak empirical evidence of a link between reported attitudes and discrimination. In this article, we use survey data on people’s attitudes towards ethnic minorities combined with a direct measure of ethnic discrimination from a field experiment in the Swedish housing market to re-examine this policy-relevant issue. We find clear evidence of a link between reported attitudes towards ethnic minorities and the extent of ethnic discrimination: in regions where attitudes are more negative, there is more discrimination, and vice versa. Thus, in contrast to most prior studies, our results suggest that reported attitudes may be a useful predictor of ethnic discrimination.     

Factors determining the efficacy of nuclear delivery of antisense oligonucleotides by gold nanoparticles

The present study investigates the applicability of nanoparticle delivery vectors for two-stage targeting that involves both cell entry by endocytosis and nuclear targeting using viral peptide signals. A nanoparticle vector consists of four components: a carrier nanoparticle, a stabilizer, targeting peptides, and a therapeutic cargo. Extensive study of bovine serum albumin (BSA)-peptide stabilized nanoparticle conjugates demonstrated limitations of these systems due to colloidal instability when oligonucleotides and multiple peptides were attached to the BSA protein. We found that the widely used protein streptavidin (SA) was an appropriate alternative to BSA for cell-targeting experiments. Targeting peptides and gene splicing oligonucleotides were attached to SA-nanoparticles using biotin labels. The present study uses a gene-splicing assay as a test for oligonucleotide delivery to the cell nucleus. Successful modification of gene splicing by an antisense oligonucleotide indicates that the latter must have crossed the plasma membrane, entered the nucleus, found the target sequence in the newly transcribed pre-mRNA, and hybridized to it in the spliceosome strongly enough to displace the splicing factors designed to interact with the target sequence. Targeting nanoparticles that carry gene-splicing oligonucleotides were compared with a control experiment that used lipofectamine (LF). While enhanced activity was observed in the control experiment, in the presence of LF, no gene splicing was observed for the nanoparticle targeting vectors without LF. We conclude that sequestration of cargo from the harsh conditions of the endosome is a desirable strategy for cell-targeting nanoparticles.