Search

Introduction: The hepatic oxidative metabolism is essential for the biotransformation of a large number substances, among which are found many drugs which are commonly used in clinical practice. The nutritional status of individuals has been shown to be of influence on this function. Aging produces a deterioration of the hepatic oxidative metabolism, without the cause for this situation having been clarified. Also, aging modifies the body composition of the individuals. The objective of this study is to evaluate whether the modifications which arise in the nutritive status due to age, can alter the hepatic oxidative capacity., Material and Methods: 165 elderly people of both sexes were studied, with an average age of 82 years, and 24 young people, with an average age of 29 years. All participants were subjected to a clinical questionnaire, along with an evaluation of anthropometric, biochemical, and immunological nutritive parameters. The study of the oxidative metabolism was conducted by evaluating the kinetics of antipyrine., Results: The elderly people showed a decrease in the antipyrine clearance rate (Ap Cl) (P < 0.001), and a lengthening of their life-span (P < 0.05) with respect to the younger people. There was a significant correlation in the elderly people, between the Ap Cl and age, weight, size, the distribution volume, and the muscular area of the arm. A multiple regression analysis showed a predictive value which was independent for age, the AST, the lymphocytes, and size., Conclusion: Elderly people have a marked depression of the hepatic oxidative metabolism. The factors which participate in their nutritional situation, are of influence on this function. It is necessary to keep all the above in mind when it comes to prescribing drugs which require this type of biotransformation, in order to avoid adverse effects or drug interactions.

Cholesterol is an essential component of all tissues, as it is a part of the structure of cell membranes, and it is an immediate precursor of a series of essential substances such as vitamins, steroid hormones, and bile acids. Under physiologic conditions, the intake and output of cholesterol in the organism is coordinated and balanced with the aim of guaranteeing the availability of adequate amounts of cholesterol to satisfy the needs of the different tissues (fig. 1). Under pathological conditions there is an imbalance between these mechanism, which leads to an increase in the circulating levels of cholesterol, leading to pathological processes such as hyperlipemias, atherosclerosis and bile stones. The liver plays a central role in the regulation of the homeostasis of cholesterol. The molecule enters the liver in the form of chylomicrons and low density lipoproteins (LDL), through lipoprotein receptors, and this is also the most important organ for the de novo biosynthesis of cholesterol from acetyl coenzyme A, by means of a cascade enzyme reaction in which the enzyme 3-hydroxy-3 methyl glutaryl CoA reductase (HMG-CoA) is the key of the entire process. Cholesterol is found in the liver in the form of cholesterol esters or as free cholesterol. The two most effective ways of eliminating body cholesterol are found in the liver, with the degradation of the compound to bile acids and the biliary secretion of cholesterol. The conversion to bile acids takes place through a series of enzymatic steps in which the formation of 7-alpha-hydroxycholesterol by the enzyme cholesterol 7-alpha-hydroxylase is the key of the process. The biliary secretion of cholesterol is 600 mg/day. Both the abundance and the universality of cholesterol in living things as its clinical implications emphasize the importance and interest of this compound.