Application of a Key Events Dose-Response Analysis to Nutrients: A Case Study with Vitamin A (Retinol)

The methodology used to establish tolerable upper intake levels (UL) for nutrients borrows heavily from risk assessment methods used by toxicologists. Empirical data are used to identify intake levels associated with adverse effects, and Uncertainty Factors (UF) are applied to establish ULs, which in turn inform public health decisions and standards. Use of UFs reflects lack of knowledge regarding the biological events that underlie response to the intake of a given nutrient, and also regarding the sources of variability in that response. In this paper, the Key Events Dose-Response Framework (KEDRF) is used to systematically consider the major biological steps that lead from the intake of the preformed vitamin A to excess systemic levels, and subsequently to increased risk of adverse effects. Each step is examined with regard to factors that influence whether there is progression toward the adverse effect of concern. The role of homeostatic mechanisms is discussed, along with the types of research needed to improve understanding of dose-response for vitamin A. This initial analysis illustrates the potential of the KEDRF as a useful analytical tool for integrating current knowledge regarding dose-response, generating questions that will focus future research efforts, and clarifying how improved knowledge and data could be used to reduce reliance on UFs

Fatal intoxication with naftidrofuryl

A 52-year-old man was found dead in his bed. He had financial and psychosocial problems like separation from his wife and children or unemployment due to alcoholism. Under treatment of disulfiram he was presently abstinent from alcohol. As he had suffered from epileptic seizures and dizziness, he received valproic acid and the vasodilator naftidrofuryl, respectively. Autopsy showed no morphologic cause of death. Chemical analysis of blood revealed concentrations for valproic acid and disulfiram in the therapeutic and above the therapeutic range but far below the lethal level, respectively. No ethanol was found. However, the very high concentration of 7500 μg/L naftidrofuryl in whole blood was considered as cause of death, and the most probable manner of death seemed to be suicide. To our knowledge, this is the first reported case of a fatal poisoning with naftidrofuryl

Differential effect of long-term leucine supplementation on skeletal muscle and adipose tissue in old rats: an insulin signaling pathway approach

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Impact of mucosal healing on long-term outcomes in ulcerative colitis treated with infliximab: a multicenter experience

International audienceBACKGROUND:Mucosal healing can be achieved with infliximab (IFX).AIM:To assess the impact of mucosal healing on long-term outcomes in patients with ulcerative colitis (UC) when treated with infliximab (IFX) beyond 1 year.METHODS:All consecutive adult patients with refractory UC receiving maintenance treatment with IFX in five French referral centres were analysed retrospectively. Only patients who had endoscopic evaluation between 6 and 52 weeks following IFX initiation were included. According to their Mayo endoscopic sub-score, patients were categorised into mucosal healing (sub-score: 0-1) and no mucosal healing (2-3). Outcome measures were colectomy and IFX failure defined by drug withdrawal due to secondary failure among primary responders.RESULTS:Of the 63 patients (30 women; median age: 38 years), 30 (48%) achieved mucosal healing. The median follow-up duration was 27 (3-79) months. Colectomy-free survival rates at 12, 24 and 36 months were, respectively, 100%, 96% and 96% in patients with mucosal healing. The corresponding figures were, respectively, 80%, 65% and 65% in patients without mucosal healing (P = 0.004). By multivariate analysis, mucosal healing was the only factor associated with colectomy-free survival, with an odds ratio of 18.01 (95%CI: 1.58-204.92). IFX failure-free survival rates at 12, 24 and 36 months were, respectively, 76%, 69% and 64% in patients with mucosal healing, and 44%, 25% and 21% in those without mucosal healing (P = 0.003).CONCLUSION:Patients with refractory UC who achieved mucosal healing after IFX initiation had better long-term outcomes, with significantly less colectomy and less IFX failure