Glucose-lipid ratio is a determinant of nitrogen balance during total parenteral nutrition in critically ill patients: a prospective, randomized, multicenter blind trial with an intention-to-treat analysis.

OBJECTIVE: Protein sparing, the major goal of nutritional support, may be affected by the glucose/lipid ratio. This study in critically ill patients compared the efficacy and tolerance of two isocaloric isonitrogenous total parenteral nutritions (TPN) having different glucose/lipid ratios. DESIGN: Multicentric prospective randomized study. PATIENTS: 47 patients with SAPS I score higher than 8 and requiring exclusive TPN. INTERVENTIONS: Patients received glucose/lipid ratios of 50/50 or 80/20. For 7 days all patients received 32 glucidolipidic kcal/kg and 0.27 g/kg nitrogen daily. All-in-one bags were prepared using industrial mixtures and a fat emulsion. MEASUREMENTS AND RESULTS: We determined TPN efficacy by nitrogen balance, urinary 3-methylhistidine/creatinine ratio, transthyretin and tolerance by glycemia, and liver enzymes. After controlling for five variables with significant effects, patients receiving the 50/50 ratio during TPN had significantly higher nitrogen balance than those receiving the 80/20 ratio. The daily difference in mean nitrogen sparing effect in favor of the latter group was 1.367 g (95% CI 0.0686-2.048). Glycemia on day 4 and gamma-glutamyltranspeptidase on day 8 were higher in group receiving the the 80/20 ratio. CONCLUSIONS: In critically ill patients TPN at a glucose/lipid ratio of 80/20 ratio induces a small nitrogen sparing effect compared to the ratio of 50/50, at the expense of poorer glycemic control. The clinical significance is unclear.

Identification of target mRNAs for the clock-controlled RNA-binding protein Chlamy 1 from Chlamydomonas reinhardtii.

An endogenous clock regulates the temporal expression of genes/mRNAs that are involved in the circadian output pathway. In the green alga Chlamydomonas reinhardtii, a clock-controlled RNA-binding protein (Chlamy 1) was identified recently, which represents an analog of the circadian trans-acting factor CCTR from the phylogenetically diverse alga Gonyaulax polyedra. In order to identify in C. reinhardtii target mRNAs that can be recognized by Chlamy 1, gel mobility-shift assays and UV-crosslinking experiments were carried out, and revealed that this protein interacts specifically with the 3' untranslated regions of several mRNAs and recognizes them all via a common cis-acting element, composed of at least seven UG repeats. By using competition assays, it was found that the affinity of Chlamy 1 is highest for mRNAs whose products are key components of nitrogen and CO2 metabolism. Since the activities of enzymes involved in nitrogen metabolism vary in a temporal pattern that is opposite in phase to that of Chlamy 1 binding activity, the protein may repress the translation of the cognate mRNAs.