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Albany, CA, United States

Silva C.J.,Foodborne Contaminants Research Unit
INFORM - International News on Fats, Oils and Related Materials | Year: 2010

Development of advanced tandem mass spectrometers has allowed multiple reaction monitoring (MRM) approach to mass spectrometric analysis and detection of prion and prion protein pathogens present in detergents that are cause of various infectitious diseases in humans and animals. MRM method was used to analyze prion peptides and a time course experiment was allowed to follow the increase of prions in hamsters intracranially challenged with a strain of hamster-adapted scrapie. MRM method allowed the quantification of amount of methionine sulfoxide present in the prions and it was found that the amount of oxidation present in the early samples decreased over time, while the amount of oxidation was similar to that found in prion. The observed oxidation is more consistent with partial oxidation of femtomole amounts of methionine-containing proteins and peptides that can occur in samples that are exposed to molecular oxygen. Source

Rasooly R.,Foodborne Contaminants Research Unit | Rasooly R.,Albany Research Center | Do P.M.,Foodborne Contaminants Research Unit | Friedman M.,Produce Safety and Microbiology Research Unit
Journal of Agricultural and Food Chemistry | Year: 2010

The foodborne pathogen Staphylococcus aureus produces the virulent staphylococcal enterotoxin A (SEA), a single-chain protein that consists of 233 amino acid residues with a molecular weight of 27'‰078 Da. SEA is a superantigen that is reported to contribute to animal (mastitis) and human (emesis, diarrhea, atopic dermatitis, arthritis, and toxic shock) syndromes. Changes of the native structural integrity may inactivate the toxin by preventing molecular interaction with cell membrane receptor sites of their host cells. In the present study, we evaluated the ability of one commercial and two freshly prepared apple juices and a commercial apple polyphenol preparation (Apple Poly) to inhibit the biological activity of SEA. Dilutions of freshly prepared apple juices and Apple Poly inhibited the biological activity of SEA without any significant cytotoxic effect on the spleen cells. Additional studies with antibody-coated immunomagnetic beads bearing specific antibodies against the toxin revealed that SEA added to apple juice appears to be largely irreversibly bound to the juice constituents. The results suggest that food-compatible and safe anti-toxin phenolic compounds can be used to inactivate SEA in vitro and possibly also in vivo, even after induction of T-cell proliferation by long-term exposure to SEA. The significance of the results for microbial food safety and human health is discussed. © This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society. Source

Rasooly R.,Foodborne Contaminants Research Unit | Hernlem B.,Foodborne Contaminants Research Unit | He X.,Foodborne Contaminants Research Unit | Friedman M.,Healthy Processed Foods Research Unit
Toxins | Year: 2015

Bacillus cereus is an important food pathogen, producing emetic and diarrheal syndromes, the latter mediated by enterotoxins. The ability to sensitively trace and identify this active toxin is important for food safety. This study evaluated a nonradioactive, sensitive, in vitro cell-based assay, based on B. cereus toxin inhibition of green fluorescent protein (GFP) synthesis in transduced monkey kidney Vero cells, combined with plant extracts or plant compounds that reduce viable count of B. cereus in food. The assay exhibited a dose dependent GFP inhibition response with ~25% inhibition at 50 ng/mL toxin evaluated in culture media or soy milk, rice milk or infant formula, products associated with food poisonings outbreak. The plant extracts of green tea or bitter almond and the plant compounds epicatechin or carvacrol were found to amplify the assay response to ~90% inhibition at the 50 ng/mL toxin concentration greatly increasing the sensitivity of this assay. Additional studies showed that the test formulations also inhibited the growth of the B. cereus bacteria, likely through cell membrane disruption. The results suggest that the improved highly sensitive assay for the toxin and the rapid inactivation of the pathogen producing the toxin have the potential to enhance food safety. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source

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