Comparison of intestinal absorption of cholesterol with different plant sterols in man*

Abstract. Intestinal absorption of cholesterol, campes-terol, campestanol, stigmasterol and sitosterol were measured in 10 healthy subjects by an intestinal perfusion technique over a 50 cm segment of the upper jejunum using sitostanol as non-absorbable marker. Cholesterol absorption was highest and averaged 33%, whereas the absorption rate of sitosterol averaged 4.2% and of stigmasterol 4.8%. Higher absorption rates were found for campesterol (9.6%). Canipestanol, the 5a saturated derivative of campesterol, showed the highest absorption rate (12.5%) of all plant sterols. A positive correlation between the absorption rate of cholesterol and campesterol was established. In addition, there was a negative correlation between the ratio of sitosterol to cholesterol and the mass of cholesterol absorption. These results are in agreement with previous observations in animal studies, namely, that increasing the length of the side-chain of cholesterol decreases the absorbability of the sterol. Surprisingly, campestanol, the 5α saturated derivate of campesterol, was shown to have higher absorbability compared with its unsaturated compound. This finding is in contrast to previous assumptions, that hydrogenisa-tion of the nucleus double bond of a sterol causes a decrease of absorbability, as has been demonstrated for cholesterol/cholestanol and sitosterol/sitostanol.     

The adaptation of composite materials to etched enamel surfaces

The adaptation of three composite materials and one unfilled bis-GMA resin to etched enamel surfaces was investigated by examining under optical and scanning electron microscopy the adhesive-enamel junction of replicas. The length of the tags and the density of tagging observed on the replicas showed that the three composite materials, Adaptic, Concise and Delphic, adapted to the etched enamel surface equally as well as the unfilled resin Nuva Seal. The results of this study together with available results of mechanical testing and clinical studies allow the conclusion that the successful retention of the composite filling materials to an etched enamel surface is not dependent on the use of an intermediate unfilled resin or bonding agent.