Palliative stenting for late malignant gastric outlet obstruction.

Malignant gastric outlet obstruction (MGO) is a late complication of pancreatobiliary and gastric cancers. Although surgical gastrojejunostomy provides good palliation, many of these patients may be nonoperative candidates or underwent previous extensive resection such as a Whipple procedure. Recently, endoscopically placed self-expanding metallic stents (SEMS) have been used to palliate MGO. The aim of this study was to evaluate the efficacy of SEMS for palliation of late MGO. Medical records of patients with endoscopic placement of SEMS for palliation of MGO were reviewed. Results showed that 30 patients with MGO had SEMS placed for late gastroduodenal (n = 20) or jejunal (n = 10) obstruction. Twenty-one patients (70%) had previous surgery. Return to oral feeding was observed in 90% of patients who presented with recurrent obstruction after prior bypass surgery and in 88% of nonoperative patients in whom SEMS were placed as the primary therapy for obstruction. No major complications were observed, and median survival after SEMS was 4.1 months (0.1 to 10.5 months). SEMS also did not interfere with biliary drainage. In conclusion, endoscopically placed SEMS are safe and provide good palliation for late malignant gastroduodenal and jejunal strictures and are an excellent complement to recurrent obstruction after surgical gastrojejunostomy.

Gallbladder myocytes are short and cholecystokinin-resistant in obese diabetic mice.

BACKGROUND: Obesity is associated with diabetes and gallstone formation. Obese leptin-deficient (Lepob) and leptin-resistant (Lepdb) mice are hyperglycemic and have enlarged gallbladders with diminished response in vitro to cholecystokinin (CCK) and acetylcholine (ACh). Whether this phenomenon is secondary to hyperosmolar myocytes and/or decreased neuromuscular transmission remains unclear. We hypothesize that myocytes from Lepob and Lepdb obese mice would not respond normally to neurotransmitters. METHODS: Cholecystectomy was performed on 39 lean, 19 Lepob, and 20 Lepdb 12-week-old female mice. The gallbladder was divided and enzymatically digested. Half of each gallbladder's myocytes had contraction induced by CCK (10(-8) mol/L, n = 38) or ACh (10(-5) mol/L, n = 40). RESULTS: Body weights, gallbladder volumes, and serum glucoses were greater for Lep(ob) and Lepdb mice compared to controls (P < .001). Resting myocyte lengths from Lepob and Lepdb mice were 93% and 91% of the length of controls (P < .001). In response to CCK, lean myocytes shortened 6% (P < .01), while myocytes from obese mice demonstrated no shortening. None of the myocytes demonstrated significant shortening with ACh. CONCLUSIONS: These data suggest that gallbladder myocytes from obese mice are (1) foreshortened and (2) have a diminished response to cholecystokinin. We conclude that altered leptin and/or increased glucose may foreshorten myocytes and decrease response to cholecystokinin.

Leptin-resistant obese mice have paradoxically low biliary cholesterol saturation.

BACKGROUND: Human obesity is associated with leptin resistance, elevated serum glucose and lipids, hepatic steatosis, and cholesterol gallstone formation. These gallstones are thought to result from hypersecretion of biliary cholesterol as well as biliary stasis. Leptin-resistant Lep(db) obese mice, which are known to have elevated serum leptin, glucose, and lipids, as well as hepatic steatosis, should be an appropriate model for human gallstone formation. Therefore, we tested the hypothesis that leptin-resistant mice would have increased gallbladder volume, biliary cholesterol saturation, and cholesterol crystal formation. METHODS: Sixty lean control mice and 60 Lep(db) obese mice on a low cholesterol chow diet were studied. Gallbladder volumes were measured and bile was pooled to calculate cholesterol saturation index. Serum cholesterol, glucose, and leptin levels were determined from pooled serum. Hepatic fat vacuoles were counted. Bile from a second group of 90 lean control and 59 obese mice was observed microscopically for cholesterol crystal formation. RESULTS: Leptin-resistant obese mice have significantly higher serum cholesterol, glucose, and leptin levels, hepatic fat vacuoles, and gallbladder volume than lean control mice. However, biliary cholesterol saturation index and cholesterol crystal formation were significantly diminished in the obese mice. CONCLUSIONS: These data suggest that leptin-resistant Lep(db) obese mice have (1) increased gallbladder volume, (2) decreased biliary cholesterol saturation despite elevated serum cholesterol and hepatic steatosis, and (3) decreased in vitro cholesterol crystal formation. We conclude that the link between obesity and gallstone formation does not require hypersecretion of biliary cholesterol.

Nonobese diabetic mice have diminished gallbladder motility and shortened crystal observation time.

Diabetes and obesity are strongly associated and are risk factors for cholesterol gallstone disease. Leptin-deficient and leptin-resistant diabetic obese mice have enlarged, hypomotile gallbladders. In addition, bile from gallbladders of leptin-deficient mice has enhanced cholesterol crystal formation, whereas bile from gallbladders of leptin-resistant mice has delayed crystal observation time. To determine the effect of diabetes alone, we hypothesized that leptin-normal, nonobese diabetic (NOD) mice would have reduced biliary motility and rapid crystal formation. Twenty control and 9 prediabetic and 11 diabetic NOD, 12- to 26-week-old mice underwent glucose measurement and cholecystectomy for muscle bath stimulation with neurotransmitters. An additional group of 200 control and 78 NOD 12-week-old mice underwent microscopic bile examination for cholesterol crystal formation. Compared with control mice, prediabetic NOD mice had similar glucose levels and gallbladder volumes. Diabetic NOD mice had higher sugar levels and larger gallbladder volumes (P < 0.001) than control mice. Prediabetic NOD gallbladders had less contractility (P < 0.01) than control gallbladders, and contractility worsened (P < 0.01) in diabetic NOD mice. NOD mice formed cholesterol crystals earlier than did control mice (P < 0.05). Nonobese diabetic NOD mice have (1) decreased gallbladder contraction to neurotransmitters, which worsens with development of diabetes, and (2) rapid crystal formation. We conclude that diabetes alone alters gallbladder motility and cholesterol crystal formation.

Leptin regulates gallbladder genes related to gallstone pathogenesis in leptin-deficient mice.

BACKGROUND: Little is known about the genetic factors that cause alterations in gallbladder motility, cholesterol crystal nucleation, biliary lipids, and, ultimately, cholesterol gallstones. Obese, leptin-deficient (Lep(ob)) mice have large gallbladder volumes with decreased contraction in vitro and are predisposed to cholesterol crystal formation. Leptin administration to these mice causes weight loss and restores gallbladder function. We hypothesize that administration of leptin to Lep(ob) mice would cause weight loss, decrease gallbladder volume, and change gallbladder genes related to gallbladder motility, nucleating factors, and lipid metabolism. STUDY DESIGN: Twenty-four 8-week-old Lep(ob) mice were fed a nonlithogenic diet for 4 weeks. Twelve mice received daily IP saline injections, and 12 received 5 mug/g recombinant leptin. Gallbladder mRNA was pooled and analyzed on murine genome microarray chips. Selected genes were confirmed by real-time polymerase chain reaction (PCR) in a second group of mice treated by the same protocol. RESULTS: Leptin-deficient mice given leptin had significant weight loss and reductions in gallbladder volume. These mice had upregulation of the leptin receptor (p = 0.007; PCR = 1.1-fold increase) but downregulation of leptin (p = 0.003; PCR = 13.5-fold decrease). Leptin upregulated the cholecystokinin A receptor (p < 0.001; PCR = 3.1-fold increase), acetylcholine beta2 receptor (p = 0.005), and the Ca+-calmodulin-dependent protein kinase (p = 0.002) genes. Leptin also altered immunoglobulin heavy chain 4 (p = 0.005; PCR = 17.7-fold increase), mucin 3 (p = 0.006), and carboxylesterase (p = 0.016; PCR = 2.5-fold decrease) genes. Leptin downregulated 3-hydroxy 3-methylglutaryl coenzyme A reductase (p = 0.006; PCR = 2.5-fold decrease) and LDL receptor (p = 0.003). CONCLUSIONS: Leptin modulates obesity and regulates gallbladder genes related to cholesterol gallstone pathogenesis.

Leptin regulates gallbladder genes related to absorption and secretion.

Dysregulation of gallbladder ion and water absorption and/or secretion has been linked to cholesterol crystal and gallstone formation. We have recently demonstrated that obese, leptin-deficient (Lep(ob)) mice have enlarged gallbladder volumes and decreased gallbladder contractility and that leptin administration to these mice normalizes gallbladder function. However, the effect of leptin on gallbladder absorption/secretion is not known. Therefore, we sought to determine whether leptin would alter the expression of genes involved in water and ion transport across the gallbladder epithelium. Affymetrix oligonucleotide microarrays representing 39,000 transcripts were used to compare gallbladder gene-expression profiles from 12-wk-old control saline-treated Lep(ob) and from leptin-treated Lep(ob) female mice. Leptin administration to Lep(ob) mice decreased gallbladder volume, bile sodium concentration, and pH. Leptin repletion upregulated the expression of aquaporin 1 water channel by 1.3-fold and downregulated aquaporin 4 by 2.3-fold. A number of genes involved in sodium transport were also influenced by leptin replacement. Epithelial sodium channel-alpha and sodium hydrogen exchangers 1 and 3 were moderately downregulated by 2.0-, 1.6-, and 1.3-fold, respectively. Carbonic anhydrase-IV, which plays a role in the acidification of bile, was upregulated 3.7-fold. In addition, a number of inflammatory cytokines that are known to influence gallbladder epithelial cell absorption and secretion were upregulated. Thus leptin, an adipocyte-derived cytokine involved with satiety and energy balance, influences gallbladder bile volume, sodium, and pH as well as multiple inflammatory cytokine genes and genes related to water, sodium, chloride, and bicarbonate transport.

Ciliary neurotrophic factor restores gallbladder contractility in leptin-resistant obese diabetic mice.

BACKGROUND: Obesity and diabetes are major risk factors for cholesterol gallstones, and the majority of obese people are leptin-resistant. Our previous work has shown that both leptin-deficient (Lepob) and leptin-resistant (Lepdb) obese diabetic mice have decreased in vitro gallbladder motility. Leptin administration to leptin-deficient (Lepob) animals restores gallbladder motility and reverses obesity and hyperinsulinemia. However, additional leptin in leptin-resistant obesity would not be expected to improve obesity-related parameters. Recent studies demonstrate that ciliary neurotrophic factor (CNTF) reduces weight and hyperinsulinemia in leptin-resistant obesity. Our hypothesis is that CNFT would cause weight loss, lower blood sugars, and restore gallbladder contractility in leptin-resistant (Lepdb) mice. MATERIALS AND METHODS: 20 C57b/6J and 20 Lepdb 8-week-old female mice were injected daily with either intraperitoneal saline or 0.3 microg/g CNTFAx15 for 17 days. Gallbladders were mounted in muscle baths and stimulated with acetylcholine, neuropeptide Y, and cholecystokinin. Gallbladder volume, serum glucose, insulin, liver weight, liver fat, and gallbladder responses were measured. Data were analyzed by ANOVA. RESULTS: Saline treated obese mice had greater body weight and obesity parameters, but decreased gallbladder contractility to neurotransmitters compared to saline treated lean mice. CNTF administration to obese mice decreased body weight and obesity parameters, and restored gallbladder contractility. CNTF treated lean animals had weight loss and decreased gallbladder contraction to acetylcholine and cholecystokinin compared to saline treated lean animals. CONCLUSIONS: Ciliary neurotrophic factor (CNTF) causes 1) weight loss, 2) improvement of diabetes, and 3) alterations in gallbladder motility that is improved in obese mice but decreased in lean mice. We conclude that CNTF may improve gallbladder contractility in leptin-resistant obesity with diabetes.

Leptin increases small intestinal response to cholecystokinin in leptin-deficient obese mice.

INTRODUCTION: Leptin receptors are present in the jejunum, ileum, and vagal neurons. Leptin increases duodenal secretion of cholecystokinin (CCK) and acts with CCK on vagal mechanoreceptors in the regulation of small intestinal motility. We have demonstrated that leptin-deficient (Lepob) obese mice have increased jejunal and normal ileal responses to CCK. Therefore, we hypothesized that leptin administration alters small intestinal motility observed in leptin-deficient obese mice. MATERIALS AND METHODS: Twelve-week-old female leptin-deficient (Lepob) obese mice received either saline (n=12) or 5 microg/g leptin ip (n=12) injections daily. After 4 weeks, jejunal and ileal segments were harvested, mounted in an organ bath, and reacted with acetylcholine (ACh, 10(-5)M) and CCK (10(-8,-7,-6)M). Data were expressed as N/cm2 and compared by ANOVA and Student's t test. RESULTS: The average body weights in the leptin-treated group were significantly decreased compared to those of the saline-treated group (34 versus 49 g, P <0.01). Jejunal responses to ACh within each group were significantly decreased (P <0.05) when compared to ileal responses. No significant differences in responses to ACh were observed between groups. Jejunal responses to 10(-7,-6)M CCK in the leptin-treated group were significantly greater than those in the saline-treated group. Ileal responses in the leptin group were similarly increased at all CCK concentrations. CONCLUSIONS: These data suggest that daily leptin administration for 4 weeks in leptin-deficient (Lepob) obese mice increases jejunal and ileal responses to CCK and does not alter responses to ACh. Therefore, we conclude that regulation of small intestinal motility may be influenced by synergistic action of cholecystokinin and leptin.

Altered intestinal motility in leptin-deficient obese mice.

INTRODUCTION: Leptin is produced by adipocytes and causes satiety by regulating hypothalamic neurotransmission and energy expenditure. Leptin functions through the active long form of its receptor, which is expressed throughout the gastrointestinal tract, including the vagal neurons concerned with small intestinal motility. However, the role of leptin in small intestinal motility is poorly understood. Therefore, we hypothesized that leptin-deficient (Lepob) obese mice would have altered small intestinal response to neurotransmitters and transit time. MATERIALS AND METHODS: Responses of jejunal and ileal segments from lean control and leptin-deficient obese animals to acetylcholine (ACh) and cholecystokinin (CCK) were determined in an organ bath. In addition, gastric emptying was determined as the amount of gavaged liquid diet remaining in the stomach after 1 h, and intestinal transit time was determined by calculating the geometric center (GC) of passage of a fluorescent-labeled marker. RESULTS: Leptin deficiency resulted in increased jejunal responses to CCK (P <0.05) and a similar response to ACh compared to lean controls. Also, gastric emptying (97% versus 91%, P <0.001) in obese mice was greater. Overall small intestinal transit (GC) in obese mice was decreased (7.3 versus 8.4, P <0.05) even though proximal transit was increased (5.3 versus 1.5, P <0.06). CONCLUSIONS: These studies indicate that leptin-deficient (Lepob) obese mice have an increased jejunal response to CCK as well as an increased proximal intestinal transit, but an overall decrease in small intestinal transit.

Diminished gallbladder motility in Rotund leptin-resistant obese mice.

BACKGROUND: Obesity is a risk factor for cholesterol gallstone formation, but the pathogenesis of this phenomenon remains unclear. Most human obesity is associated with diabetes and leptin-resistance. Previous studies from this laboratory have demonstrated that diabetic leptin-resistant (Lep(db)) obese mice have low biliary cholesterol saturation indices, enlarged gallbladders and diminished gallbladder response to neurotransmitters. Recently, a novel leptin-resistant mouse strain Lepr(db-rtnd) (Rotund) has been discovered. Rotund mice are also obese, diabetic, and have an abnormal leptin receptor. Therefore, we tested the hypothesis that leptin-resistant obese Rotund mice would have large gallbladders and reduced biliary motility. METHODS: Eight-week-old control (C57BL/6J, N=12) and Rotund leptin-resistant (Lepr(db-rnd), N=9) mice were fed a non- lithogenic diet for four weeks. Animals were fasted and underwent cholecystectomy. Gallbladder volumes were recorded, and contractile responses (N/cm(2)) to acetylcholine (10(-5) M), Neuropeptide Y (10(-8,-7,-6) M), and cholecystokinin (10(-10,-9,-8,-7) M) were measured. Results were analyzed using the Mann-Whitney Rank Sum Test. RESULTS: Compared to control mice, Rotund mice had larger body weights, higher serum glucose levels, and greater gallbladder volumes (p<0.05). Rotund gallbladders had less contractility (p<0.05)) to acetylcholine and cholecystokinin than control mice. Responses to Neuropeptide Y were also less, but not statistically significant, in the Rotund mice. CONCLUSIONS: These data suggest that leptin-resistant Rotund mice have (1) enlarged gallbladders with (2) diminished contractility compared to lean control mice. Therefore, this study confirms that leptin-resistance is associated with abnormal biliary motility and may lead to gallstone formation in leptin-resistant obesity.

Leptin-resistant obese mice do not form biliary crystals on a high cholesterol diet.

INTRODUCTION: Human obesity is associated with leptin resistance and cholesterol gallstone formation. Previously, we demonstrated that leptin-resistant (Lep(db)) obese mice fed a low cholesterol diet have enlarged gallbladders, but a decreased cholesterol saturation index, despite elevated serum cholesterol. Obese humans, however, consume a high cholesterol diet. Therefore, we hypothesized that on a high cholesterol diet, leptin-resistant mice would have cholesterol saturated bile and would form biliary crystals. METHODS: Eight-week old female lean control (n = 70) and leptin-resistant (n = 72) mice were fed a 1% cholesterol diet for 4 weeks. All animals then had cholecystectomies. Bile was collected, grouped into pools to determine cholesterol saturation index (CSI), and examined for cholesterol crystals. Serum cholesterol and leptin were also measured. RESULTS: Gallbladder volumes for Lep(db) mice were enlarged compared with the lean mice (35.8 microl versus 19.1 microl, P < 0.001), but the CSI for the Lep(db) mice was lower than for the lean animals (0.91 versus 1.15, P < 0.03). The obese animals did not form cholesterol crystals, whereas the lean animals averaged 2.2 crystals per high-powered field (hpf) (P < 0.001). Serum cholesterol and leptin were also elevated (P < 0.001) in the obese animals. CONCLUSIONS: These data suggest that Lep(db) obese mice fed a high cholesterol diet have increased gallbladder volume and decreased biliary cholesterol saturation and crystal formation despite elevated serum cholesterol compared with lean control mice. We conclude that the link among obesity, diet, and gallstone formation may not require hypersecretion of biliary cholesterol and may be related to the effects of diabetes, hyperlipidemia, or both on gallbladder motility.

Isolation and characterization of human esophageal microvascular endothelial cells: mechanisms of inflammatory activation.

Gastroesophageal reflux disease is the most common malady of the esophagus, affecting 7% of the United States population. Histological assessment demonstrates classic inflammatory mechanisms including selective leukocyte recruitment and hemorrhage, suggesting a prominent role for the microvasculature. We isolated and characterized human esophageal microvascular endothelial cells (EC) (HEMEC), examined inflammatory activation in response to cytokines, LPS, and acidic pH exposure, and identified signaling pathways that underlie activation. HEMEC displayed characteristic morphological and phenotypic features including acetylated LDL uptake. TNF-alpha/LPS activation of HEMEC resulted in upregulation of the cell adhesion molecules (CAM) ICAM-1, VCAM-1, E-selectin, and mucosal addressin CAM-1 (MAdCAM-1), increased IL-8 production, and enhanced leukocyte binding. Both acid and TNF-alpha/LPS activation lead to activation of SAPK/JNK in HEMEC that was linked to VCAM-1 expression and U-937 leukocyte adhesion. Expression of constitutive inducible nitric oxide synthase in HEMEC was in marked contrast to intestinal microvascular endothelial cells. In this study, we demonstrate that HEMECs are phenotypically and functionally distinct from lower gut-derived endothelial cells and will facilitate understanding of inflammatory mechanisms in esophageal inflammation.