Stomach Region Stimulated Determines Effects on Duodenal Motility in Rats

Gastric electrical stimulation (GES) is used clinically to promote proximal GI emptying and motility. In acute experiments, we measured duodenal motor responses elicited by GES applied at 141 randomly chosen electrode sites on the stomach serosal surface. Overnight-fasted (H2O available) anesthetized male rats (n = 81) received intermittent biphasic GES for 5 min (20s-on/40s-off cycles; I = 0.3mA; pw = 0.2ms; 10 Hz). A strain gauge on the serosal surface of the proximal duodenum of each animal was used to evaluate baseline motor activity and the effect of GES. Using ratios of time blocks compared to a 15-min pre-stimulation baseline, we evaluated the effects of the 5-min stimulation on concurrent activity; on the 10-min immediately after the stimulation, and on the 15-min period beginning with the onset of stimulation. We mapped the magnitude of the duodenal response (3 different motility indices) elicited from the 141 stomach sites. Post hoc electrode site maps associated with duodenal responses suggested three zones similar to the classic regions of forestomach, corpus and antrum. Maximal excitatory duodenal motor responses were elicited from forestomach sites, whereas inhibitory responses occurred with stimulation of the corpus. Moderate excitatory duodenal responses occurred with stimulation of the antrum. Complex, weak inhibitory/excitatory responses were produced by stimulation at boundaries between stomach regions. Patterns of GES efficacies coincided with distributions of previously mapped vagal afferents, suggesting that excitation of the duodenum is strongest when GES electrodes are situated over stomach concentrations of vagal intramuscular arrays, putative stretch receptors in the muscle wall.

The prognostic significance of macroscopic serosal change in subserosal invasion (stage T3) gastric cancer

Background For patients with gastric cancer intraoperative macroscopic serosal change is not always consistent with pathological T stage. We investigated whether macroscopic serosal change is associated with unfavourable prognosis of patients with gastric cancer. Methods We reviewed 856 patients with stage T3 gastric cancer who underwent curative gastrectomy in our institution. All patients were classified as serosa negative and serosa positive according to the macroscopic serosal change during the operation. The prognostic difference between two groups was compared and clinicopathologic features were analysed. Results The percentage of macroscopic serosal change accounted for 55.7% of all patients. Compared with normal serosal surface, the patients with macroscopic serosal change had larger tumour size, more extensive stomach involvement and more advanced stage N. The prognosis of stage T3 with macroscopic serosal change was significantly poorer than that of those with normal serosal surface, especially for those with stages T3N0 and T3N1. Multivariate analysis identified macroscopic serosal change as an independent factor associated with unfavourable prognosis of stage T3 cancer. Conclusion Although the depth of tumour invasion mainly depends on pathological evaluation after surgery, the prognostic significance of intraoperative macroscopic serosal change should not be ignored for those patients with subserosal invasion.