When prototrophic yeast cells are cultured under nutrient-limited conditions that mimic growth in the wild, rather than in the high-glucose solutions used in most laboratory studies, they exhibit a robustly periodic metabolic cycle. Over a cycle of 4 to 5 hours, yeast cells rhythmically alternate between glycolysis and respiration. The cell division cycle is tightly constrained to the reductive phase of this yeast metabolic cycle, with DNA replication taking place only during the glycolytic phase. We show that cell cycle mutants impeded in metabolic cycle-directed restriction of cell division exhibit substantial increases in spontaneous mutation rate. In addition, disruption of the gene encoding a DNA checkpoint kinase that couples the cell division cycle to the circadian cycle abolishes synchrony of the metabolic and cell cycles. Thus, circadian, metabolic, and cell division cycles may be coordinated similarly as an evolutionarily conserved means of preserving genome integrity.

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Background: Roux-en-Y gastric bypass (RYGB) restricts food intake, and when the Roux limb is elongated to 150 cm, the procedure is believed to induce malabsorption. Objective: Our objective was to measure total reduction in intestinal absorption of combustible energy after RYGB and the extent to which this was due to restriction of food intake or malabsorption of ingested macronutrients. Design: Long-limb RYGB was performed in 9 severely obese patients. Dietary intake and intestinal absorption of fat, protein, carbohydrate, and combustible energy were measured before and at 2 intervals after bypass. By using coefficients of absorption to measure absorptive function, equations were developed to calculate the daily gram and kilocalorie quantities of ingested macronutrients that were not absorbed because of malabsorption or restricted food intake. Results: Coefficients of fat absorption were 92 6 1.3% before bypass, 72 6 5.5% 5 mo after bypass, and 68 6 8.7% 14 mo after bypass. There were no statistically significant effects of RYGB on protein or carbohydrate absorption coefficients, although protein coefficients decreased substantially in some patients. Five months after bypass, malabsorption reduced absorption of combustible energy by 124 6 57 kcal/d, whereas restriction of food intake reduced energy absorption by 2062 6 271 kcal/d. Fourteen months after bypass, malabsorption reduced energy absorption by 172 6 60 kcal/d compared with 1418 6 171 kcal/d caused by restricted food intake. Conclusion: On average, malabsorption accounted for '6% and 11% of the total reduction in combustible energy absorption at 5 and 14 mo, respectively, after this gastric bypass procedure. Am J Clin Nutr 2010;92:704-13.

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TEC allows detection of significantly more adenomas compared to SC in patients undergoing surveillance or diagnostic workup, but not in screening patients (ClinicalTrials.gov Identifier: NCT01044732).

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