A smart microfluidic platform for rapid multiplexed detection of foodborne pathogens
FOOD CONTROL
Authors: Azinheiro, Sarah; Kant, Krishna; Shahbazi, Mohammad-Ali; Garrido-Maestu, Alejandro; Prado, Marta; Dieguez, Lorena
Abstract
Rapid and sensitive detection of foodborne pathogens in food industry is of high importance in day-to-day practice to ensure safe food. To address this issue, multiple foodborne pathogens are targeted for rapid identification based in DNA amplification. A 3D PDMS sponge was fabricated using salt crystals as scarifying mold and functionalized with a ligand, apolipoprotein-H (ApoH), to test bacterial capturing for both Gram positive (L. monocytogenes) and negative bacteria (Salmonella spp.), in a microfluidic device. Pure culture of both pathogens in a range of similar to 10-10(5) CFU/mL were tested and the application of the developed automated pre-concentration protocol in real samples was verified using spiked surface samples after swab sampling. Bacterial DNA was extracted directly from the sponge and used for Real Time quantitative Polymerase Chain Reaction (qPCR) detection. The sponges did not show any significant resistance to sample flow and could easily be incorporated in a microfluidic device. A capture efficiency above 70% was observed for both targeted (Gram positive and Gram negative) pathogens and a Limit of Detection (LoD) in the range of 10(3) and 10(4) CFU/mL was obtained for Salmonella spp. and L. monocytogenes, respectively. Using this approached, we are able to perform multiplexed (Gram positive and Gram negative) capturing and reduce the enrichment time compared to the gold standard plate culture (over 1-day) method. The use of a 3D sponge for direct capturing of multiplexed pathogen on microfluidic device, followed by qPCR detection is an efficient and versatile method to stratify the presence of bacteria. This approach and methodology has potential to be integrated in full automatized device and used as point of need (PoN) system for foodborne pathogen stratification in food packaging/production industries.
Evidence for inhibition of low density lipoprotein oxidation and cholesterol accumulation by apolipoprotein H (beta(2)-glycoprotein I)
LIFE SCIENCES
Authors: Lin, KY; Pan, JP; Yang, DL; Huang, KT; Chang, MS; Ding, PYA; Chiang, AN
Abstract
Low density lipoprotein (LDL) oxidation and lipid accumulation are thought to enhance the progression of atherosclerosis, Apolipoprotein H (apoH) has been implicated in the development of human atherosclerosis, However, the roles of apoH in the oxidative modification of LDL and cellular accumulation of lipid constituents remained uncharacterized, In this study, the level of plasma apoH was found to be significantly associated with the oxidative susceptibility of LDL in human subjects. Plasma levels of apoH were positively correlated with the lag time but negatively correlated with LDL oxidation rate in conjugated diene formation. By using a J774 A.1 macrophage culture system, we found that apoH could not only inhibit the formation of conjugated diene and thiobarbituric acid-reactive substances, but also reduce the electrophoretic mobility of oxidized LDL. Furthermore, apoH decreased cellular accumulation of cholesterol via a reduction in cholesterol influx and an increase in cholesterol efflux, This is the first demonstration that apoH appears to have "antioxidant"-like effects on LDL oxidation. The results also suggest that apoH can inhibit the translocation of cholesterol from extracellular pools to macrophages, suggesting that apoH may play an important role in the prevention of atherosclerosis. (C) 2001 Elsevier Science Inc. All rights reserved.