Effects of temperature and agitation rate on the formation of conjugated linoleic acids in soybean oil during hydrogenation process.

The effects of hydrogen temperature and agitation rate on the formation of total conjugated linoleic acids (CLA) and CLA isomers were studied during hydrogenation with a selective Ni catalyst. The CLA isomers were identified by using a 100-m cyano-capillary column gas chromatograph and a silver ion-impregnated HPLC. Reaction temperature and agitation rate greatly affected the quantities of total CLA and individual CLA isomers, and the time to reach the maximum quantity of CLA in the partially hydrogenated soybean oil. As the hydrogenation temperature increased, the maximum quantity of CLA in soybean oil increased, but the time to reach the maximum CLA content decreased. By increasing the hydrogenation temperature from 170 to 210 degrees C, the quantity of CLA obtained was about 2.6 times higher. As the agitation rate decreased, the CLA formation in soybean oil increased, and the time to reach the maximum CLA content also increased. The maximum CLA contents in soybean oil obtained during hydrogenation at 210 degrees C with agitation rates of 300, 500, and 700 rpm were 162.82, 108.62, and 66.15 mg total CLA/g oil, respectively. The present data showed that it is possible to produce high-CLA-content soybean oil without major modification of fatty acid composition by short-time (10 min) selective hydrogenation under high temperature and low agitation rate conditions.

Identification and characterization of a radiation-inducible glycosylated human early-response gene.

A radiation-inducible immediate-early gene, IEX-1, was identified and characterized in human squamous carcinoma cells. Sequence analysis revealed 156-amino acid nucleotides, encoding a protein of Mr 20,000. The protein is glycosylated (Mr approximately 27,000) in the presence of microsomal membranes. Northern analysis reveals a 1.2-kb transcript. Treatment with cycloheximide was associated with superinduction of this transcript suggesting that it is an immediate-early gene. The abundance of IEX-1 mRNA increased rapidly after exposure of the cells to ionizing radiation (2-10 Gy), reaching a maximum by 15 min and returning subsequently to basal levels by 4 h. Expression of IEX-1 was also induced significantly by the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol-13-acetate (TPA), the protein phosphatase inhibitor okadaic acid, and tumor necrosis factor-alpha, whereas treatment of cells with UV light and H2O2 had little effect on IEX-1 expression. Cells depleted of PKC by prolonged incubation with TPA showed no attenuated IEX-1 response to tumor necrosis factor-alpha. This is the first report of IEX-1, a radiation-inducible glycosylated human protein, whose expression can be mediated through multisignal transduction pathways.