Carotenoids and retinoids: a review of research, clinical, and public health applications.

Traditionally, the carotenoids and retinoids have been regarded as dietary sources of vitamin A and have been evaluated regarding their respective physiologic roles in vision, growth, immune system integrity, and prevention of vitamin A deficiency. In the 1990s, however, vitamin A deficiency is no longer widespread in Western countries. Therefore, the role of carotenoids and retinoids is evolving to encompass treatment and prevention of conditions such as cancer and cardiovascular disease, which are prevalent in Western societies. This review summarizes current research concerning the therapeutic utility of vitamin A and its analogues and their roles in the prevention of cancer and cardiovascular disease.

Interpatient variability: genetic predisposition and other genetic factors.

Polymorphisms and other genetic factors related to enzymes metabolizing drugs and xenobiotic chemicals are well known. This article focuses on selected molecular mechanisms and introduces some of the clinical implications arising from genetically determined interpatient variability or expression in some of these enzymes. Selected are the polymorphic enzymes of cytochromes P-450 (CYP) as examples of phase I enzymes and methyl transferases, n-acetyl transferases, and glutathione-s-transferases as examples of phase II enzymes. The polymorphism surrounding arylhydrocarbon hydroxylase induction is briefly described. Phase I enzymatic reactions are predominantly oxidative, whereas phase II reactions often couple with the byproducts of phase I. Overall, in poor metabolizers, whether phase I or phase II, there is limited metabolism in most patients unless another major metabolic pathway involving other enzymes exists. Drug metabolism also depends on whether the parent compound is a prodrug that forms an active metabolite, and poor metabolizers under this condition will form only trace amounts of an active compound. Therefore, the clinical significance of genetic polymorphisms and other genetic factors may be related to substrate, metabolite, or the major elimination pathway.

The effect of caffeine on pregnancy outcome variables.

The American public consumes a wide array of caffeinated products as coffee, tea, chocolate, cola beverages, and caffeine-containing medication. Therefore, it seems of value to inform both the scientific community and the consumer about the potential effects of excessive caffeine consumption, particularly by pregnant women. The results of this literature review suggest that heavy caffeine use (> or = 300 mg per day) during pregnancy is associated with small reductions in infant birth weight that may be especially detrimental to premature or low-birth-weight infants. Some researchers also document an increased risk of spontaneous abortion associated with caffeine consumption prior to and during pregnancy. However, overwhelming evidence indicates that caffeine is not a human teratogen, and that caffeine appears to have no effect on preterm labor and delivery. More research is needed before unambiguous statements about the effects of caffeine on pregnancy outcome variables can be made.