Two kinds of high-speed liquid chromatographic methods using either ultraviolet or a fluorometric detector (HSLC-UV and HSLC-fluorometric methods) are described for the determination of ubiquinones (UQ). HSLC-UV method: Serum or liver was saponified with methanolic alkaline solution containing pyrogallol as an antioxidant and 2, 3, 6trimethyl-5-nonaprenyl-l, 4-benzoquinone as an internal standard and then extracted with n-hexane. The extract was evaporated and then dissolved in dioxane. The resulting solution was applied to a HSLC system using a Permaphase ODS column, ethanol-water (80:20) as a mobile phase and a high sensitivity UV detector (275 nm). HSLC-fluorometric method: Serum was deproteinized with ethanol and then extracted with n-hexane. The resulting extract was reacted with alkaline ethylcyanoacetate (ECA) reagent to give fluorescence. The reacted solution was applied to a HSLC system using a Permaphase ODS column, ethanol-water (75:25) as a mobile phase and a spectrofluorometer (Ex. 430 nm, Em. 530 nm). Neither of the proposed HSLC methods were affected by other fat-soluble substances and seemed to be more simple, sensitive and specific than other conventional determination methods.
The interactions between Bifidobacterium b fldum N4 (B. bfidum) and Escherichia coli K-12 (E. coli) were investigated in their mixed cultures. Under conditions in which both bacteria grew well in their pure culture, B. bifldum inhibited the growth of E. coli even when the latter was inoculated at 104-fold and preincubated for 41 hr. The inhibition in the mixed cultures appeared when the pH values were reduced below 4.6. When the lowering of pH was prevented by the addition of NaOH, no inhibition was observed. At the same initial pH of 6.5, lactic acid andd acetic acid, metabolites of B. b fidum, had more inhibitory effect on the growth of E. coli than other aliphatic fatty acids. On the other hand, in the mixed cultures with E. coli, B. bfidum grew in the absence of its essential vitamins, riboflavin and pantetheine and, furthermore, aerobically.
The present study deals with the mechanism causing fatty infiltration in the liver of rats fed casein that had been incubated with oxidized lipids (casein : ethyl linoleate, 2:1 w/w) at 50°C and RH 80.4% for 14 days and defatted. The increase in the content of liver triglyceride associated with feeding the reacted casein at the 9% level was not alleviated by dietary supplementation of major amino acids that had been lost during incubation. In contrast, when the amino acid mixtures simulating either the unreacted (control) or reacted casein were given to rats, there were no demonstrable differences in the contents of liver triglyceride between these two. These observations suggested that the accumulation of liver triglyceride due to feeding the reacted casein is not attributable to the loss of amino acids accompanied by lipid oxidation. Rather, regression of hydrolysis of the reacted casein and hence the unbalanced rate of liberation of absorbable hydrolysates (free amino acids and oligopeptides) in the intestinal tract appears to be one of the factors responsible for causing the observed abnormality in the metabolism of hepatic triglyceride.