Preoperative feeding does not reverse postoperative insulin resistance in skeletal muscle in the rat.

Metabolic studies on injured and postoperative patients have shown impaired glucose disposal in peripheral tissues after trauma. Using small-bowel resection as a model of surgical trauma, we investigated whether substrate availability could ameliorate the changes in muscle glucose uptake induced by trauma. We also studied the effect of preoperative feeding on postoperative insulin-stimulated insulin receptor substrate-1 (IRS-1)-associated phosphatidylinositol (PI) 3-kinase activity in both Wistar rats and genetically non-insulin-dependent diabetic Goto-Kakazaki rats (GK rats). Serum glucose, insulin, plasma epinephrine, lactate, and plasma nonesterified free fatty acids (NEFAs) were measured as indicators of the metabolic state and surgical stress. Insulin-stimulated glucose transport was significantly reduced in fed traumatized Wistar rats compared with fed nontraumatized rats (P < .05). Significant increases in in vivo insulin-stimulated IRS-1-associated PI 3-kinase activity were found in fed traumatized Wistar rats compared with fed nontraumatized Wistar rats and fasted traumatized Wistar rats, as well as fed traumatized GK rats compared with fed nontraumatized GK animals (all P < .017). Serum insulin concentrations were significantly reduced in fed traumatized Wistar and GK rats compared with the respective fed nontraumatized groups (both P < .01). Serum glucose levels were significantly elevated in fed traumatized GK rats compared with fed nontraumatized animals (P < .01). In the present study, preoperative feeding did not prevent a postoperative reduction in insulin-stimulated glucose transport in skeletal muscle. The finding that insulin-stimulated PI 3-kinase activity increased after trauma in both Wistar and GK rats indicates that postoperative insulin resistance is not caused by an impairment in the early steps of the insulin signaling pathway. The postoperative decreases in serum insulin despite high blood glucose suggest that trauma impairs the insulin response to hyperglycemia.

Effect of carbohydrate feeding on insulin action in skeletal muscle after surgical trauma in the rat.

Metabolic stress after surgery is associated with peripheral insulin resistance. Recent studies have suggested that preoperative glucose can ameliorate postoperative decreases in insulin-stimulated glucose disposal. In the present experiments, we used a bowel-resection model of surgical trauma to test the hypothesis that elevations of serum insulin induced by preoperative oral glucose or ad libitum feeding affects postoperative insulin-stimulated glucose uptake in skeletal muscle. Insulin-stimulated glucose transport was measured in vitro in soleus muscles after surgical trauma in fasted rats given oral glucose or water before surgery. Insulin-stimulated glucose transport was also assessed in vitro in fasted or fed traumatized rats and non-traumatized control animals. In addition, stress hormones (glucagon, corticosterone, and adrenaline) were measured before and after surgical trauma in fasted rats and rats fed ad libitum. In vitro skeletal-muscle insulin sensitivity and responsiveness were reduced postoperatively in fasted animals that received oral glucose loads before bowel resections and in rats fed ad libitum or fasted before surgery versus non-traumatized rats (all P < 0.05). Stress-hormone concentrations after trauma did not differ between fed and fasted animals. In the current study, insulin sensitivity and responsiveness were reduced in isolated skeletal muscles after bowel resection, but neither preoperative glucose supplementation nor free intake of mixed nutrients ameliorated the development of postoperative insulin resistance.

Acute colonic diverticulitis: a systematic review of diagnostic accuracy.

OBJECTIVE: To appraise the literature on the diagnosis of acute colonic diverticulitis by ultrasound (US), computed tomography (CT), barium enema (BE) and magnetic resonance imaging (MRI). METHOD: The databases of Pub Med, the Cochrane Library and EMBASE were searched for articles on the diagnosis of diverticulitis published up to November 2005. Studies where US, CT, BE, or MRI were compared with a reference standard on consecutive or randomly selected patients were included. Three examiners independently read the articles according to a prespecified protocol. In case of disagreement consensus was sought. The level of evidence of each article was classified according to the criteria of the Centre for Evidence-Based Medicine (CEBM), Oxford, UK. RESULTS: Forty-nine articles relevant to the subject were found and read in full. Twenty-nine of these were excluded. Among the remaining 20 articles, only one study, evaluating both US and CT reached level of evidence 1b according to the CEBM criteria. Two US studies and one MRI study reached level 2b. The remaining studies were level 4. CONCLUSION: The best evidence for diagnosis of diverticulitis in the literature is on US. Only one small study of good quality was found for CT and for MRI-colonoscopy.