Anticatabolic Effects of Avoiding Preoperative Fasting by Intravenous Hypocaloric Nutrition
Bibliographic record
Abstract
OBJECTIVE: We tested the hypothesis that the avoidance of preoperative fasting by hypocaloric nutrition attenuates protein catabolism after surgery. SUMMARY BACKGROUND DATA: Prolonged fasting before major abdominal procedures has been demonstrated to accentuate the catabolic response to surgery. METHODS: Twenty-two patients undergoing colorectal cancer surgery were randomly assigned to receive glucose and amino acids intravenously starting either 20 hours before the operation or with surgical skin incision. Nutrition was administered until the second postoperative day, with glucose providing 50% and amino acids 20% of each patient's measured resting energy expenditure. Whole body leucine and glucose kinetics were assessed by L-[1-(13)C]leucine and [6,6-(2)H(2)]glucose before and after surgery. Fractional synthesis rates of muscle protein, albumin, and fibrinogen were determined using primed continuous infusions of L-[(2)H(5)]phenylalanine postoperatively, whereas the expression of mRNA of proteolytic genes in muscle (Mafbx/atrogin-1, ubiquitin, Murf 1) was determined by quantitative RT-PCR. Circulating concentrations of glucose, lactate, amino acids, insulin, glucagon, and cortisol were also measured. This study has been registered at ClinicalTrials.gov (Identifier: NCT00614133). RESULTS: Preoperative feeding inhibited endogenous protein breakdown (fasting group: 128 +/- 23 micromol . kg(-1) . h(-1); nutrition group: 96 +/- 22 micromol . kg(-1) . h(-1); P = 0.02) and blunted the increase in amino acid oxidation (fasting group: 27 +/- 5 micromol . kg(-1) . h(-1); nutrition group: 20 +/- 5 micromol . kg(-1) . h(-1); P = 0.03), resulting in positive whole-body protein balance after surgery (fasting group: -10 +/- 4 micromol . kg(-1) . h(-1); nutrition group: 1 +/- 3 micromol . kg(-1) . h(-1); P < 0.001). This anabolic response was associated with decreased muscle proteolytic gene expression and increased hepatic albumin synthesis. Total plasma protein, fibrinogen, and muscle protein synthesis were not affected. CONCLUSIONS: Hypocaloric nutrition decreases protein catabolism, with a contribution from the ubiquitin pathway in muscle, and stimulates albumin synthesis after colorectal surgery if initiated 1 day before the operation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".