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Burlington, Canada

Farias N.,University of Guelph | Ho N.,University of Guelph | Butler S.,University of Guelph | Delaney L.,University of Guelph | And 3 more authors.
Journal of Nutritional Biochemistry | Year: 2015

Folate and its synthetic form, folic acid (FA), are essential vitamins for the regeneration of S-adenosyl methionine molecules, thereby maintaining adequate cellular methylation. The deregulation of DNA methylation is a contributing factor to carcinogenesis, as alterations in genetic methylation may contribute to stem cell reprogramming and dedifferentiation processes that lead to a cancer stem cell (CSC) phenotype. Here, we investigate the potential effects of FA exposure on DNA methylation and colonosphere formation in cultured human colorectal cancer (CRC) cell lines. We show for the first time that HCT116, LS174T, and SW480 cells grown without adequate FA demonstrate significantly impaired colonosphere forming ability with limited changes in CD133, CD166, and EpCAM surface expression. These differences were accompanied by concomitant changes to DNA methyltransferase (DNMT) enzyme expression and DNA methylation levels, which varied depending on cell line. Taken together, these results demonstrate an interaction between FA metabolism and CSC phenotype in vitro and help elucidate a connection between supplemental FA intake and CRC development. © 2015 The Authors. Source

Shahrzad S.,Investigative Science Inc. | Ford J.,Investigative Science Inc. | Sagara C.,Investigative Science Inc. | Flatley M.,Suncor Energy
Fuel Processing Technology | Year: 2013

Trace sulfur species, such as elemental sulfur, hydrogen sulfide, and volatile alkyl mercaptans, adversely affect silver based devices, such as gasoline level sensors, used in most vehicles. Identification and measurement of the sulfur species are key to developing a process control and/or treatment system to solve the problem at the refinery, prior to product distribution. A new and innovative method was developed for the analysis of specific mercaptan species in gasoline, and is reported here. The initial sample treatment stage is precipitation and stabilization of mercaptans as silver mercaptides. This stabilization could be successfully utilized in the field to mitigate the instability of mercaptans in gasoline samples. Another advantage of this step is that silver nitrate (AgNO3) precipitation concentrates the mercaptans allowing for trace level detection. The silver mercaptides are converted to pentafluorobenzyl derivatives and analyzed by gas chromatography (GC) with mass spectrometric (MS) detection. Results based on this technique show that alkyl mercaptans can be accurately measured in the full scan mode of MS with a limit of detection (LOD) of 0.02 mg/L when a 100 mL gasoline sample is used. The recovery of mercaptans spiked into gasoline was 85 to 120% (n = 5). Gasoline producers will find knowing the exact levels of mercaptans in their products a useful tool to avoid distribution delays. © 2013 Elsevier B.V. Source

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