The generation of oxygen radicals during leukocyte-endothelial cell interaction is considered to represent one of the fundamental steps of microvascular injury following ischemia and reperfusion. Indirect evidence also suggests that this relationship may be important following hemorrhagic shock. The purpose of this study was to characterize the temporal changes of reactive oxygen species (ROS) in the mesenteric microvascular endothelium, in vivo, as a consequence of hemorrhagic shock and reperfusion, and to correlate this ROS production to leukocyte adherence. Following a control period, blood was withdrawn to reduce the mean arterial pressure to 40 mmHg for 1 h in urethane-anesthetized rats. Mesenteric venules in a transilluminated segment of small intestine were examined to quantitate changes in ROS generation and leukocyte adherence. Sprague-Dawley rats were injected with dihydrorhodamine 123, a hydroperoxide-sensitive fluorescent probe that is trapped within viable cells as a nonfluorescent form and then converted to the mitochondrion-selective form rhodamine 123 by hydroperoxides. The fluorescent light emission from rhodamine 123 was recorded with digital microscopy and downloaded to a computerized image analysis program. Our results demonstrated an 80% increase in ROS generation beginning within 5 min into resuscitation and a 10-fold increase in leukocyte adherence that occurred at 10 min after resuscitation. Both ROS generation and leukocyte adherence were attenuated with pre-shock administration of platelet activating factor (PAF) antagonist, WEB 2086, and the CD11/CD18a antibody, anti-LFA-1beta. Our findings suggest that ROS production in endothelial cells is increased during reperfusion following hemorrhagic shock and that the mechanism of expression is mediated in part by both PAF expression and subsequent leukocyte adherence.

Prognosis of gastrinoma patients with metastases to lymph nodes only is uncertain, and the true nature of isolated nodal gastrinomas remains controversial. The purpose of this study was to determine the outcome of such patients and whether nodal gastrinomas may occur as primary lesions. Eleven patients with nodal involvement but without hepatic metastases are reported (mean follow-up of 129 months). Primary gastrinomas were located in the duodenum in seven (Group 1) and not identified in four (Group 2). In Group 1, five patients remained eugastrinemic after excision of all gross tumors and gastrectomy (n = 4) or pancreaticoduodenectomy (n = 1), one patient had residual disease and died of other causes (survival of 88 months), and one patient had MEA-I syndrome with multiple gastrinomas (follow-up of 126 months). In Group 2, three patients became eugastrinemic after nodal excision and total gastrectomy (mean follow-up of 212 months) and may represent primary nodal gastrinomas, and in one patient, liver metastases developed and the patient died. Four deaths occurred in a 27-year period, but only one was tumor-related. There was no significant difference in 20-year survival rates between the two groups (85% vs. 75%). It is concluded that 1) lymph node gastrinomas are usually metastatic from primary duodenal lesions, 2) although rare, nodal gastrinomas may occur as primary lesions, and 3) in the absence of hepatic metastases, lymph node gastrinomas, whether primary or metastatic, have a good prognosis and should not deter aggressive surgical treatment.

Conventional microelectrode techniques were combined with unilateral mucosal ionic substitutions to determine the effects of luminal pH and luminal alkali-earth cation concentrations on apical membrane cation permeability in Necturus gallbladder epithelium. Acidification of the mucosal solution caused reversible depolarization of both cell membranes and increase of transepithelial resistance. Low pH media also caused: (a) reduction of the apical membrane depolarization induced by high K, and (b) increase of the apical membrane hyperpolarization produced by Na replacement with Li or N-Methyl-D-glucamine. These results, in conjunction with estimates of cell membrane conductances, indicate that acidification of the luminal solution produces a reduction of apical membrane K permeability (PK). Addition of alkali earth cations (Mg2+, Ca2+, Sr2+, or Ba2+) produced cell membrane depolarization, increase of relative resistance of the luminal membrane and reduction of the apical membrane potential change produced by a high-K mucosal medium. These results, as those produced by low pH, can be explained by a reduction of apical membrane PK. The effects of Ba2+ on membrane potential and relative apical membrane PK were larger than those of all other four cations at all concentrations tested (1-10 mM). The effect of Sr2+ was significantly larger than those of Mg2+ and Ca2+ at 10 mM, but not different at 5 mM. The reduction of PK produced by mucosal acidification appears to be mediated by: (a) nonspecific titration of membrane fixed negative charges, and (b) an effect of luminal proton activity on the apical K channel. Divalent cations reduce apical membrane PK probably by screening negative surface charges. The larger magnitude of the effects of Ba2+ and Sr2+ can be explained by binding to membrane sites, in the surface or in the K channel, in addition to their screening effect. We suggest that the action of luminal pH on K secretion in some segments of the renal tubule could be mediated in part by this pH-dependent K permeability of the luminal membrane.

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Background: Adenocarcinoma of the small bowel is a relatively rare malignancy as compared to the other malignancies of the gastrointestinal tract. Nonspecific presentation and infrequent occurrence often leads to a delay in diagnosis and consequent poor prognosis. Various other factors are of prognostic importance while managing these tumors.

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The effects of luminal instillation of 16,16-dimethyl prostaglandin E2 (dmPGE2) on total gastric blood flow and its fractional distribution between the layers of gastric tissue were determined in exteriorized segments of the greater curvature of dog stomach. Total gastric blood flow was measured simultaneously by venous outflow and alpha-labeled microspheres; both methods correlated well with each other (r = 0.88, P less than 0.01). In the nonstimulated stomach, dmPGE2 caused an increase in total gastric blood flow from 4.2 +/- 0.8 to 7.4 +/- 1.2 ml/min (P less than 0.05). In contrast, dmPGE2 significantly reduced gastric blood flow in histamine-stimulated stomach (from 14.6 +/- 1.2 to 9.2 +/- 1.0 ml/min; P less than 0.01). The changes in mucosal blood flow ere proportional to the alterations in total blood flow because the fractional distribution of blood flow to the mucosa remained relatively unchanged during dmPGE2 administration. These observations suggest that dmPGE2, a known vasodilator, induces an increase in gastric blood flow in the resting stomach, whereas it reduces gastric blood flow in the actively secreting stomach as a result of secretory inhibition.