Pharmacological ascorbate with gemcitabine for the control of metastatic and node-positive pancreatic cancer (PACMAN): results from a phase I clinical trial

BACKGROUND

Treatment for pancreatic cancer with pharmacological ascorbate (ascorbic acid, vitamin C) decreases tumor progression in preclinical models. A phase I clinical trial was performed to establish safety and tolerability of pharmacological ascorbate combined with gemcitabine in patients with biopsy-proven stage IV pancreatic adenocarcinoma.

DESIGN

Nine subjects received twice-weekly intravenous ascorbate (15-125 g) employing Simon's accelerated titration design to achieve a targeted post-infusion plasma level of ≥350 mg/dL (≥20 mM). Subjects received concurrent gemcitabine. Disease burden, weight, performance status, hematologic and metabolic laboratories, time to progression and overall survival were monitored.

RESULTS

Mean plasma ascorbate trough levels were significantly higher than baseline (1.46 ± 0.02 vs. 0.78 ± 0.09 mg/dL, i.e., 83 vs. 44 μM, p < 0.001). Adverse events attributable to the drug combination were rare and included diarrhea (n = 4) and dry mouth (n = 6). Dose-limiting criteria were not met for this study. Mean survival of subjects completing at least two cycles (8 weeks) of therapy was 13 ± 2 months.

CONCLUSIONS

Data suggest pharmacologic ascorbate administered concurrently with gemcitabine is well tolerated. Initial data from this small sampling suggest some efficacy. Further studies powered to determine efficacy should be conducted.

Inhibitors of hydroperoxide metabolism enhance ascorbate-induced cytotoxicity

Pharmacological ascorbate, via its oxidation, has been proposed as a pro-drug for the delivery of H(2)O(2) to tumors. Pharmacological ascorbate decreases clonogenic survival of pancreatic cancer cells, which can be reversed by treatment with scavengers of H(2)O(2). The goal of this study was to determine if inhibitors of intracellular hydroperoxide detoxification could enhance the cytotoxic effects of ascorbate. Human pancreatic cancer cells were treated with ascorbate alone or in combination with inhibitors of hydroperoxide removal including the glutathione disulfide reductase inhibitor 1,3 bis (2-chloroethyl)-1-nitrosurea (BCNU), siRNA targeted to glutathione disulfide reductase (siGR), and 2-deoxy-D-glucose (2DG), which inhibits glucose metabolism. Changes in the intracellular concentration of H(2)O(2) were determined by analysis of the rate of aminotriazole-mediated inactivation of endogenous catalase activity. Pharmacological ascorbate increased intracellular H(2)O(2) and depleted intracellular glutathione. When inhibitors of H(2)O(2) metabolism were combined with pharmacological ascorbate the increase in intracellular H(2)O(2) was amplified and cytotoxicity was enhanced. We conclude that inclusion of agents that inhibit cellular peroxide removal produced by pharmacological ascorbate leads to changes in the intracellular redox state resulting in enhanced cytotoxicity.

Role of Rac1-dependent NADPH oxidase in the growth of pancreatic cancer

K-ras mutations occur in as high as 95% of patients with pancreatic cancer. K-ras activates Rac1-dependent NADPH oxidase, a key source of superoxide. Superoxide plays an important role in pancreatic cancer cell proliferation and scavenging or decreasing the levels of superoxide inhibits pancreatic cancer cell growth both in vitro and in vivo. DNA microarray analysis and RT-PCR has demonstrated that Rac1 is also upregulated in pancreatic cancer. The aim of this study was to determine if inhibiting Rac1 would alter pancreatic tumor cell behavior. Human pancreatic cancer cells with mutant K-ras (MIA PaCa-2), wild-type K-ras (BxPC-3), and the immortal H6c7 cell line (pancreatic ductal epithelium) expressing K-ras oncogene (H6c7eR-KrasT) that is tumorigenic, were infected with a dominant/negative Rac1 construct (AdN17Rac1). In cells with mutant K-ras, AdN17Rac1 decreased rac activity, decreased superoxide levels, and inhibited in vitro growth. However in the BxPC-3 cell line, AdN17Rac1 did not change rac activity, superoxide levels, or in vitro cell growth. Additionally, AdN17Rac1 decreased superoxide levels and inhibited in vitro growth in the KrasT tumorigenic cell line, but had no effect in the immortalized H6c7 cell line. In human pancreatic tumor xenografts, intratumoral injections of AdN17Rac1 inhibited tumor growth. These results suggest that activation of Rac1-dependent superoxide generation leads to pancreatic cancer cell proliferation. In pancreatic cancer inhibition of Rac1 may be a potential therapeutic target.

Autotrophic picoplankton in the tropical ocean

In phytoplankton of the eastern tropical Pacific Ocean from 25 to 90 percent of the biomass (measured as chlorophyll a) and 20 to 80 percent of the inorganic carbon fixation were attributable to particles that could pass a screen with a 1-micrometer pore diameter. Evidence is presented that these are indeed autotrophic cells and not cell fragments.

Mesoscale Iron Enrichment Experiments 1993-2005: Synthesis and Future Directions

Since the mid-1980s, our understanding of nutrient limitation of oceanic primary production has radically changed. Mesoscale iron addition experiments (FeAXs) have unequivocally shown that iron supply limits production in one-third of the world ocean, where surface macronutrient concentrations are perennially high. The findings of these 12 FeAXs also reveal that iron supply exerts controls on the dynamics of plankton blooms, which in turn affect the biogeochemical cycles of carbon, nitrogen, silicon, and sulfur and ultimately influence the Earth climate system. However, extrapolation of the key results of FeAXs to regional and seasonal scales in some cases is limited because of differing modes of iron supply in FeAXs and in the modern and paleo-oceans. New research directions include quantification of the coupling of oceanic iron and carbon biogeochemistry.

Lipopolysaccharide temporarily impairs sphincter of Oddi motility

The aim of our study was to determine the effect of lipopolysaccharide (LPS) on sphincter of Oddi (SO) motility. Opossums received saline, Escherichia coli LPS (1.0 mg/kg), or E. coli LPS (1.0 mg/kg) and aminoguanidine (50 mg/kg), and the SO was removed 6-24 h later. At 12 h LPS decreased electrical field stimulation (EFS)-induced relaxation and increased baseline tone. These changes were reversed when the animals were pretreated with aminoguanidine. The dose-dependent decrease in EFS-induced relaxation by N(omega)-nitro-l-arginine was impaired after LPS, but not in animals that received LPS and aminoguanidine. The impaired EFS-induced relaxation after LPS was reversed when l-arginine was added to the tissue bath. Serum levels of NO(-)(2)/NO(-)(3) were increased with LPS as compared to saline or both LPS and aminoguanidine. Inducible nitric oxide synthase mRNA was readily seen in SO segments after LPS. LPS impairs EFS-induced relaxation and increases baseline tone of the SO. The effects of LPS on SO motility appear to be mediated by nitric oxide.

Metabolism of superoxide dismutase during the adynamic ileus of endotoxemia

Endotoxemia is accompanied by gastrointestinal motor disturbances while administration of oxygen free radical scavengers following endotoxemia ameliorates these motor disturbances. We hypothesized that the motor disturbance produced by endotoxemia may be associated with a change in the activity or production of superoxide dismutase (SOD). Strain gauge transducers were placed on the stomach and small bowel of dogs to determine fasting gastrointestinal motility. Manganese and copper/zinc SOD enzyme activities in gut smooth muscle were measured and protein expression was analyzed by Western blotting. Following completion of the baseline studies, dogs were given a single dose of <i>Escherichia coli</i> lipopolysaccharide, 200 µg/kg i.v., and the studies repeated for the next 3 days. Following endotoxin bolus, the migrating motor complex (MMC) was delayed for 2 days while gastric and jejunal smooth muscle levels of Cu/Zn SOD activity were decreased for 1 day in the stomach and for 2 days in the jejunum. Western blotting indicated that endotoxin did not change the amount of SOD enzyme produced. We conclude that endotoxemia results in a temporary prolongation of the MMC and a decrease in Cu/Zn SOD activity. Expression of Cu/Zn SOD and Mn SOD does not seem suppressed by endotoxin as measured by Western blotting. However, the impairment of Cu/Zn SOD activity may contribute to ileus associated with sepsis by altering oxygen-free metabolism in both the stomach and jejunum.

Effect of endotoxin on opossum gallbladder motility: a model of acalculous cholecystitis

OBJECTIVE

To determine whether endotoxin causes histologic changes in the gallbladder consistent with acalculous cholecystitis, and to determine the effects of endotoxin on gallbladder motility.

SUMMARY BACKGROUND DATA

Acute acalculous cholecystitis is frequently seen in critically ill, septic patients, after prolonged fasting and gallbladder stasis. The pathogenesis of acalculous cholecystitis is unknown; however, previous studies have suggested that ischemia may play a role.

METHODS

Adult opossums received Escherichia coli lipopolysaccharide. The gallbladder was removed for histologic examination or for physiologic studies 4 hours to 2 weeks later. For histologic examination, gallbladder strips underwent standard hematoxylin-and-eosin processing. For physiologic studies, they were mounted in a tissue bath to determine responses to cholecystokinin octapeptide or electrical field stimulation.

RESULTS

Intravenous endotoxin at a dose of 0.005 mg/kg resulted in disrupted mucosal surfaces and areas of hemorrhage; higher doses of endotoxin resulted in coagulation necrosis, hemorrhage, areas of fibrin deposition, and extensive mucosal loss, consistent with an acute ischemic insult. Endotoxin abolished the contractile response to cholecystokinin octapeptide in gallbladder strips 4 hours after endotoxin administration. The 0.005-mg/kg dose of endotoxin decreased the contractile response to cholecystokinin octapeptide for up to 96 hours after endotoxin administration and decreased the contractile response to electrical field stimulation for 48 hours after administration. Inhibition of nitric oxide synthase reversed the decreased contractile response to cholecystokinin octapeptide.

CONCLUSIONS

Endotoxin causes an ischemic insult to the gallbladder similar to that seen in acalculous cholecystitis. Also, endotoxin may lead to gallbladder stasis by decreasing gallbladder contractile responses to hormonal and neural stimuli.

Damage to DNA in bacterioplankton: a model of damage by ultraviolet radiation and its repair as influenced by vertical mixing

A model of UV-induced DNA damage in oceanic bacterioplankton was developed and tested against previously published and novel measurements of cyclobutane pyrimidine dimers (CPD) in surface layers of the ocean. The model describes the effects of solar irradiance, wind-forced mixing of bacterioplankton and optical properties of the water on net DNA damage in the water column. The biological part includes the induction of CPD by UV radiation and repair of this damage through photoreactivation and excision. The modeled damage is compared with measured variability of CPD in the ocean: diel variation in natural bacterioplankton communities at the surface and in vertical profiles under different wind conditions (net damage as influenced by repair and mixing); in situ incubation of natural assemblages of bacterioplankton (damage and repair, no mixing); and in situ incubation of DNA solutions (no repair, no mixing). The model predictions are generally consistent with the measurements, showing similar patterns with depth, time and wind speed. A sensitivity analysis assesses the effect on net DNA damage of varying ozone thickness, colored dissolved organic matter concentration, chlorophyll concentration, wind speed and mixed layer depth. Ozone thickness and mixed layer depth are the most important factors affecting net DNA damage in the mixed layer. From the model, the total amplification factor (TAF; a relative measure of the increase of damage associated with a decrease in ozone thickness) for net DNA damage in the euphotic zone is 1.7, as compared with 2.1-2.2 for irradiance weighted for damage to DNA at the surface.

Effect of endotoxin on opossum oesophageal motor function

Endotoxin induces nitric oxide (NO*) synthase and alters gastrointestinal functions. We explored the effect of lipopolysaccharide (LPS) on oesophageal motor function at 6, 12, 24, and 48 h. The effects of inhibiting inducible NO* synthase (iNOS) were studied 12 h after administration of LPS with/without aminoguanidine (AG). Oesophageal manometry was performed and tissue bath studies were performed with muscle strips from the oesophagus and lower oesophageal sphincter (LOS). Plasma nitrite/nitrate concentrations were determined. The amplitudes of peristaltic pressure waves, resting LOS pressure and the percentage LOS relaxations were diminished by LPS. AG attenuated the decrease in amplitude of oesophageal pressure waves, LOS pressure, and percentage relaxation of LOS brought about by LPS. LPS decreased electrical field stimulation (EFS)-induced relaxation of LOS muscle. AG attenuated this decrease in LOS relaxation. The off-response of transverse oesophageal muscle strips was decreased, and AG antagonized this effect. Plasma concentrations of nitrite/nitrate were increased. The increase in plasma nitrite/nitrate was attenuated by AG. These studies support the hypothesis that endotoxin modulates oesophageal motor function by increasing NO production and suggest that this results from the induction of iNOS.

Standard Roux-en-Y gastrojejunostomy vs. "uncut" Roux-en-Y gastrojejunostomy: a matched cohort study

Roux-en-Y gastrojejunostomy is a common method of reconstruction after subtotal gastrectomy. Maintaining myoneural continuity has been proposed to decrease the incidence of Roux stasis syndrome, with an "uncut" Roux-en-Y reconstruction. The aim of our study was to compare the clinical results in patients who have undergone uncut Roux-en-Y gastrojejunostomy with those in patients who have undergone a standard Roux-en-Y gastrojejunostomy. Eleven patients underwent gastrectomy and uncut Roux-en-Y gastrojejunostomy and were compared with a cohort of 14 patients who underwent gastrectomy and standard Roux-en-Y gastrojejunostomy. Patients were contacted and charts were reviewed for Visick grade, early and late morbidity and mortality, and incidence of staple line dehiscence. Early postoperative morbidity was 18% in patients undergoing uncut Roux gastrojejunostomy and 28% in patients undergoing standard Roux reconstruction. There were no early postoperative deaths in either group. In the patients undergoing the uncut Roux procedure, no cases of staple line dehiscence were detected clinically (mean follow-up 9 months, range 1 to 48 months). Visick grade improved following the uncut Roux procedure, but changed little after standard Roux reconstruction. Uncut Roux-en-Y gastrojejunostomy can be performed safely with improvement in symptoms. The uncut Roux procedure may provide an alternative for reconstructive gastric surgery.

Are gastric, jejunal, or both forms of enteral feeding gastroprotective during stress?

BACKGROUND

Clinical data suggest enteral nutrition prevents stress ulceration and intragastric nutrients prevent restraint-induced gastric injury. The purpose of these studies was to determine if jejunal nutrients can protect without gastric contact and to determine if gastric pH, motility, or mucosal perfusion is affected.

METHODS

In Experiment 1, 27 rats were restrained for 2 h at room temperature followed by 2 h in cold (4 degrees C), with intragastric (IG) or intrajejunal (IJ) 2 ml/h infusions of saline or 25% glucose. Gastric lesions, pH, volumes, and glucose concentrations were measured postmortem. In Experiment 2, 23 rats had gastric strain gauges implanted >5 days prior to a 0.5 ml/h IG or IJ infusion during stress. In Experiment 3, 40 rats were anesthetized for laser Doppler measurements of gastric mucosal perfusion and arterial catheter monitoring of systemic hemodynamics. Rats received 0.5-ml boluses of concentrated glucose or saline IG or IJ, and were monitored for 60 min.

RESULTS

(1) The 2 ml/h IJ and IG glucose infusions prevented gastric injury, but the elevated gastric glucose concentrations suggested equal gastric contact. (2) The 0.5 ml/h glucose IG and IJ infusions decreased gastric injury without reflux of the IJ glucose into the stomach and suppressed stress-induced hypercontractility, but not acidity. (3) Systemic perfusion pressures were unaffected by enteral glucose. IG glucose had little effect on gastric mucosal perfusion, while IJ glucose decreased gastric perfusion within 5 min.

CONCLUSIONS

These studies show that large volumes of enteral glucose prevent restraint injury but IJ glucose refluxes into the stomach. The gastroprotective effects of small, nonrefluxing volumes of IJ glucose are associated with suppression of stress-induced gastric hypercontractility, but not with suppressed acidity or enhanced perfusion.

Preventing Staphylococcus infections in high-risk patients

UP to 30% of those who undergo surgery potentially develop a surgical site infection depending on the procedure performed. Infection increases the risk of further complications, lengthens hospital stays and increases management costs. A significant proportion of surgical site infections are caused by Staphyloccoccus spp. and prior nasal carriage is a risk factor for post surgical infection.

Characterization of the off response to electrical field stimulation in gallbladder smooth muscle

BACKGROUND

Low-frequency electrical stimulation of intramural nerves of gut smooth muscle produces an "off response," that is, a contraction that occurs after electrical field stimulation (EFS) of the intramural nerves is stopped. The off response coincides with a depolarization of the muscle following an EFS-induced hyperpolarization of that muscle. The aims of our study were to determine if the off response is present in gallbladder smooth muscle and to determine the mechanisms involved in this nerve-mediated response.

MATERIALS AND METHODS

Gallbladder strips from opossums were placed in Krebs solution and passed through bipolar ring electrodes for EFS of intramural nerves, and isometric force measurements were recorded. Dose-response curves were determined with N(G)-nitro-L-arginine (L-NNA) a competitive inhibitor of nitric oxide (NO) synthase; 1H-¿1,2,4ŏxadiazolol¿4, 3aquinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase; and oxyhemoglobin, a scavenger of nitric oxide.

RESULTS

A contraction termed the off response occurred shortly after EFS ended. The off response was abolished with tetrodotoxin and atropine. The amplitude of the off response increased with increasing voltage. The amplitude of the off response decreased by 41% with L-NNA 1.5 mM. Preincubation of the tissue with L-arginine (1 mM) prevented the inhibition of amplitude seen with L-NNA. The amplitude of the off response decreased by 43% with oxyhemoglobin (40 microM) and by 56% with ODQ (250 microM).

CONCLUSION

We conclude that the off response is present in gallbladder smooth muscle after low-frequency EFS. NO may be a mediator of this off response and of nonadrenergic noncholinergic responses in gallbladder smooth muscle.

Gastric emptying of liquids and postprandial pancreatobiliary secretion are temporarily impaired during endotoxemia

The aims of our study were to determine mechanisms by which pancreatobiliary secretion is altered during endotoxemia. Dogs underwent placement of duodenal perfusion and aspiration catheters and antral manometry catheters. Gastric emptying of liquids, antral motility, output of bile acids and amylase, and serum levels of enteric hormones were determined after ingestion of a 360-kcal mixed-nutrient liquid meal. Each dog was then given a single dose of E. coli lipopolysaccharide (200 microg/kg, intravenously) and the studies repeated for the next three days. Endotoxin slowed gastric emptying of liquids and decreased amylase output for two days. Bile acid output was decreased on postendotoxin day 1. Pancreatic polypeptide alone was decreased on postendotoxin day 1. We conclude that the decrease in pancreatobiliary output is probably due to decreased nutrient flow into the duodenum and not due to decreased production of hormones that influence pancreatobiliary secretion. The delayed gastric emptying, decreased pancreatobiliary output, and decreased postprandial levels of pancreatic polypeptide suggest diminished vagal output as a possible explanation for the effects of endotoxin on upper gut function.

The cup is half full

BACKGROUND

The clinical outcomes following feeding tube procedures are infrequently studied because most patients have other incurable conditions.

METHODS

Multiple electronic databases were used to track clinical outcomes following all gastrostomies and jejunostomies performed at a single institution from October 1, 1992, through December 31, 1995. Preoperative risk factors and postoperative morbidity were available for all 104 cases; long-term status was available for all but 2 of 104.

RESULTS

The in-hospital mortality was 11.4%. Mortality was lower in those receiving feeding tubes as primary procedures (7.4%) than in those who had a feeding tube placed during other major procedures (24%, P <0.05). Postoperative pneumonia was frequent (24.7%), and was associated with preoperative gastroesophageal reflux (odds ratio 4.2, P = 0.01) and history of aspiration (odds ratio 3.9, P = 0.01). Although 14.5% of the patients were newly discharged to care facilities, the majority (74%) returned to their previous residence. Median survival was just over 6 months, with 18% surviving more than 2 years. Survival was inversely related to do-not-resuscitate status (odds ratio 4.6, P <0.001), metastatic tumor (odds ratio 2.7, P <0.001), dementia (odds ratio 2.3, P = 0.005), and unresectable tumor (odds ratio 2.1, P <0.001), but was unrelated to type of feeding tube.

CONCLUSIONS

Significant morbidity and mortality follow feeding enterostomies, but the majority of patients benefit and can return to their previous residence. Am J Surg. 1999;178:406-410. 1999 by Excerpta Medica, Inc.

The role of antioxidant enzymes in the control of opossum gallbladder motility

BACKGROUND

Superoxide rapidly oxidizes nitric oxide (NO) to form peroxynitrite, thus terminating the biological activity of NO. The aims of our study were to determine if superoxide alters the motor function of the gallbladder and to localize the antioxidant enzymes in the gallbladder.

MATERIALS AND METHODS

Immunostaining and immunoblots were performed and enzyme activities were measured in the gallbladder. In physiologic experiments, force-displacement transducers recorded tension in gallbladder muscle strips. Superoxide was generated by the addition of xanthine with xanthine oxidase, while superoxide radicals were scavenged by the addition of superoxide dismutase (SOD) and catalase. SOD was inhibited by deithyldithiocarbamate.

RESULTS

Immunostaining demonstrated superoxide dismutase and catalase immunoreactivity in ganglia situated throughout the smooth muscle. Total superoxide dismutase activity was 115 +/- 12 U/mg. Western blots detected expression of proteins of 19.4 kDa for copper/zinc SOD and 25.0 kDa for manganese SOD. Generation of superoxide increased isometric tension, while pretreatment with SOD prevented the increase in isometric tension induced by superoxide. Inhibition of SOD diminished the EFS-induced off response.

CONCLUSIONS

We conclude that superoxide alters gallbladder motor function, and the presence of superoxide scavenging enzymes in enteric plexuses suggests that they may regulate gallbladder neuromuscular function by clearing endogenous superoxide.

Effects of endotoxin on regulation of intestinal smooth muscle nitric oxide synthase and intestinal transit

BACKGROUND

The disrupted intestinal transit during endotoxemia may be mediated by nitric oxide (NO). We hypothesized that the isoforms of nitric oxide synthase (NOS) are up-regulated in intestinal smooth muscle during endotoxemia and that the scavenging of NO will normalize transit.

METHODS

Rats were given Escherichia coli lipopolysaccharide (LPS) 10 mg/kg intravenously and were killed 4 hours later. To determine the activity of NOS isoforms in the jejunum and ileum, the conversion of tritiated L-arginine to tritiated L-citrulline was measured. Western immunoblots were performed by incubating the extracted protein with specific polyclonal antibodies. To determine intestinal transit, rats were divided into 4 groups: 0.9% sodium chloride 1 mL/h intravenously for 5 hours, LPS 10 mg/kg intravenous bolus plus 1 mL/h 0.9% sodium chloride intravenously, LPS plus oxyhemoglobin 0.5 g/kg/h intravenously, and oxyhemoglobin 0.5 g/kg/h intravenously.

RESULTS

LPS increased the constitutive and inducible NOS enzyme activities in the jejunum and ileum. Western blots demonstrated that LPS up-regulates both the NOS1 and NOS2 isoforms in jejunal and ileal smooth muscle. Oxyhemoglobin alone increased intestinal transit compared with controls, whereas endotoxemia increased intestinal transit, which was ameliorated with infusions of oxyhemoglobin.

CONCLUSIONS

NO may play a major role in mediating the rapid intestinal transit induced by endotoxemia.

The effect of peroxynitrite on sphincter of Oddi motility

BACKGROUND

Nitric oxide (NO*) is an inhibitory neurotransmitter that induces sphincter of Oddi relaxation. Superoxide (O*-2)-scavenging enzymes are present in enteric plexuses of the sphincter of Oddi and O*-2 alters sphincter of Oddi motor function. O*-2 rapidly oxidizes nitric oxide (NO*) to form peroxynitrite (ONOO-), thus terminating the biological activity of NO*. The aim of our study was to determine the effects of ONOO- on sphincter of Oddi motility in vitro.

MATERIALS AND METHODS

Adult opossums were sacrificed and the sphincter of Oddi was removed and placed in a tissue bath containing oxygenated Krebs solution at 37 degreesC. In the first series of experiments, force transducers recorded tension in a transverse orientation at two sites along the spontaneously contracting sphincter of Oddi. In a second series of experiments, circular muscle strips were precontracted with carbachol and stimulated by an electrical field.

RESULTS

ONOO-, superoxide dismutase (SOD), Nomega-nitro-l-arginine (l-NNA), or oxyhemoglobin were added to the tissue baths. ONOO- decreased the frequency of contractions in the spontaneously contracting sphincter of Oddi. Adding hemoglobin increased the frequency of contractions. ONOO- also increased the stimulation-induced relaxation compared to controls. The increase in relaxation induced by ONOO- was inhibited by oxyhemoglobin and l-NNA but not SOD. Pretreatment with oxyhemoglobin prevented the increase in the stimulation-induced relaxation caused by ONOO-.

CONCLUSION

These results suggest that hemoglobin binds ONOO- or that ONOO- generates NO.

Changes in intestinal transit and absorption during endotoxemia are dose dependent

BACKGROUND

Septic patients are often intolerant of enteral feedings due to a combination of motility disturbances and impaired absorptive function. Our laboratory has previously demonstrated that endotoxemia results in rapid intestinal transit and decreased jejunal absorption of water, electrolytes, and glucose. We hypothesized that the changes in jejunal transit and absorption during endotoxemia may be dependent on the dose of endotoxin.

MATERIALS AND METHODS

Under general anesthesia, rats underwent placement of an internal jugular line, a femoral arterial line, and a 20-cm jejunal Thiry-Vella loop. The jejunal segment was perfused with an isotonic solution containing polyethylene glycol. For 90 min, baseline measurements of blood pressure, heart rate, jejunal absorption of water, electrolytes, and glucose, and jejunal transit were made. Following this baseline period I, rats were given 0.9% NaCl (1 ml/kg) or one of three doses of Escherichia coli lipopolysaccharide (0.5, 1.0, or 5.0 mg/kg). Studies were then repeated for an additional 90 min.

RESULTS

Changes in blood pressure and heart rate were similar among the four groups of animals. Endotoxin decreased water and glucose flux, increased potassium flux, and quickened intestinal transit in a dose-dependent fashion.

CONCLUSIONS

We conclude that endotoxemia causes dose-dependent changes in jejunal transit and absorption. The effects of increasing doses of endotoxin on jejunal absorptive and motor function do not appear to be mediated by changes in blood pressure or heart rate.

Vertical gastroplasty: evolution of vertical banded gastroplasty

The objective of this paper is to summarize the goals, technical requirements, advantages, and potential risks of gastroplasty for treatment of severe obesity. Gastroplasty is preferred to more complex operations, as it preserves normal digestion and absorption and avoids complications that are peculiar to exclusion operations. The medical literature and a 30-year experience at the University of Iowa Hospitals and Clinics (UIHC) provides an overview of vertical banded gastroplasty (VBG) evolution. Preliminary 10-year results with the VBG technique currently used at UIHC are included. At UIHC the VBG is preferred to other gastroplasties because it provides weight control that extends for at least 10 years and the required objective, intraoperative quality control required for a low rate of reoperation. It is recommended that modifications of the operative technique not be attempted until a surgeon has had experience with the standardized operation--and then only under a carefully designed protocol. Realistic goals for surgery and criteria of success influence the choice of operation and the optimum, lifelong risk/benefit ratio. In conclusion, VBG is a safe, long-term effective operation for severe obesity with advantages over complex operations and more restrictive simple operations.

Effect of endotoxin on canine colonic motility and transit

Diarrhea is a common problem in patients who have episodes of sepsis and are being fed enterally. Endotoxemia results in gastrointestinal motor dysfunction characterized by slowed gastric emptying and rapid intestinal transit; however, the effect of endotoxin on colonic motility is unknown. The aim of our study was to determine the effects of a single sublethal dose of endotoxin on colonic motility and transit. Seven dogs underwent construction of a 50 cm colonic Thiry-Vella fistula. Five manometry catheters were sewn into the colonic lumen at 8 cm intervals along the fistula. Following recovery, the fistula was perfused with an isotonic solution at 2.9 ml/min, and fasting and postprandial colonic motility was determined. Liquid transit was assessed by bolus of a nonabsorbable marker instilled into the proximal end of the Thiry-Vella fistula. Recordings of gastrointestinal contractile activity were made digitally to determine contractile frequencies and motility indexes. Following completion of the baseline studies, each dog was given a single dose of E. coli lipopolysaccharide, 200 microgram/kg intravenously, and studies were repeated daily for the next 3 days. Endotoxin doubled the fasting colonic contractile frequency on postendotoxin day 1 and also increased motility indexes on that same day. Fasting motility indexes and contractile activity were decreased on postendotoxin days 2 and 3. The postprandial frequency of contractions and motility indexes were decreased on postendotoxin day 3. Fasting colonic liquid transit was rapid on postendotoxin day 1, whereas postprandial liquid transit was rapid on both postendotoxin days 1 and 2. Endotoxin temporarily speeds liquid transit and increases both the frequency and strength of colonic contractions. These effects may contribute to the diarrhea that occurs during episodes of sepsis.

Gastric mucosal protection from enteral nutrients: role of motility

BACKGROUND

Cold restraint stress increases the force of gastric contractions and produces gastric mucosal injury in rats. The aim of our study was to determine whether enteral glucose or hyperglycemia alone would alter the stress-induced gastric motility pattern and ameliorate the associated gastric mucosal injury.

METHODS

Adult male rats underwent surgical placement of gastric catheters, jugular venous catheters, and gastric strain gauge transducers 5 days before cold restraint. Three groups of rats received different substances during the same cold restraint stress protocol. Group 1 received 0.9% NaCl, 2 mL/h infused both intravenously (i.v.) and intragastrically (i.g.); group 2 received 0.9% NaCl, 2 mL/h i.g. plus 25% glucose, 2 mL/h i.v.; and group 3 received 0.9% NaCl, 2 mL/h i.v. plus 25% glucose i.g. Following baseline gastric motility measurements, all rats were restrained for 2 hours at 20 degrees C followed by 2 hours at 4 degrees C.

RESULTS

Restraint even at room temperature increased the force of gastric contractions; the cold environment gradually prolonged gastric contractions. Enteral glucose blunted the effects of stress on gastric motility, increased gastric residual volume, decreased gastric acidity, and prevented gastric mucosal injury. Parenteral glucose had little effect on any gastric parameters.

CONCLUSIONS

Enteral glucose prevents the abnormal gastric motility pattern that is necessary to produce the gastric mucosal injury associated with cold restraint stress, but hyperglycemia alone has little effect on the pathophysiology of cold restraint.

Effect of hydroxyl radical (OH.) on sphincter of Oddi motility

Antioxidant enzymes are present in sphincter of Oddi nerves and regulate sphincter of Oddi motor function mediated by NO-releasing nerves. Oxygen free radicals (O2-.) produce hydrogen peroxide (H2O2) by the action of superoxide dismutase (SOD). Hydroxyl radical (OH.) has been shown to play an important role as a mediator of H2O2 toxicity. The aims of our study were to determine the effects of H2O2 on sphincter of Oddi motility and if these effects are mediated by OH.. Adult opossums were sacrificed and the sphincter of Oddi removed and placed in a tissue bath containing oxygenated Krebs solution. Force transducers recorded tension in a transverse orientation at two sites along the sphincter of Oddi specimen. H2O2 was added into the tissue bath at concentrations from 0.01 to 0.5%. O2-. radicals were inhibited by the addition of SOD, while OH. was scavenged by the addition of alcohol (ETOH) or dimethyl sulfoxide (DMSO). H2O2 produced a dose-dependent increase in baseline amplitude, frequency, and peak amplitude of contractions. The effect of 0.01% H2O2 on sphincter of Oddi contractile frequency was inhibited by 0.2% ETOH and DMSO, but not by SOD. We conclude that H2O2 has profound effects on sphincter of Oddi motility and that the actions of H2O2 are probably mediated through OH..

Endotoxin temporarily impairs canine colonic absorption of water and sodium

Diarrhea is a common manifestation of sepsis. We hypothesized that endotoxin may impair colonic absorption of water and electrolytes, an effect which may be related to altered liquid transit in the colon. Five dogs underwent construction of 50-cm colonic Thiry-Vella fistulas (TVF). Following recovery, absorption studies were performed by perfusing the TVF with an isotonic solution at 2.9 ml/min containing polyethylene glycol (5 g/L). Fasting and postprandial colonic absorption of water, electrolytes, and glucose were determined. Liquid transit was assessed by bolus of a nonabsorbable marker (PSP) instilled into the proximal end of the TVF. Following completion of the baseline studies, each dog was given a single dose of Escherichia coli lipopolysaccharide 200 micrograms/kg i.v. and the studies were repeated daily for the next 3 days. Following endotoxin bolus, colonic absorption of water and sodium were decreased during fasting, while postprandial colonic absorption of water was also decreased. Colonic absorption of water and sodium returned to baseline values on postendotoxin day 2. Colonic secretion of potassium was decreased on postendotoxin days 1 and 3 in both the fasting and the fed periods. Fasting and postprandial liquid transit was also rapid on postendotoxin day 1, which correlated with the decreased absorption seen on that day. Liquid transit returned to baseline values on postendotoxin day 2. We conclude that endotoxin temporarily impairs postprandial colonic absorption, which may be due to the rapid liquid transit that occurs. These effects may contribute to the diarrhea seen during and after septic episodes.

Gastric contractions, secretions and injury in cold restraint

The clinical syndrome of stress ulceration has been studied for years using rodent cold restraint stress models, although the pathogenesis of the characteristic focal gastric mucosal lesions produced in these models has been controversial. We used gastric strain gauges to characterize fully the gastric motility effects of a 4-h cold restraint protocol, and we determined the relationship of variations in gastric contents and in gastric contractions to the amount of gastric mucosal injury. Additionally, we examined rat stomachs histologically, and determined the location of focal haemorrhagic mucosal lesions on the mucosal rugae. We found a consistent relationship between force of gastric contractions and gastric mucosal injury, and also a relationship between the initial duration of contractions during restraint and ultimate mucosal injury. Volume, acidity and mucus in the gastric contents were unrelated to mucosal injury. The majority (91%) of the mucosal lesions had some relationship to a rugal fold, with 59% of all lesions at the base of a rugal fold. Thus, the mechanical forces of gastric hypercontractility may contribute to the gastric mucosal injury of rodent cold restraint models.

A decade of change in obesity surgery. National Bariatric Surgery Registry (NBSR) Contributors

BACKGROUND

The International (formerly National) Bariatric Surgery Registry began collecting data in January 1986. The aim of this study was to examine changes in the practice of surgical treatment of severe obesity that occurred during the decade of 1986 through 1995, as observed in the IBSR data.

METHODS

All data submitted to the IBSR during the decade were transferred to the IBM mainframe computer for analysis. Characteristics of operative type populations were compared over time using analysis of variance (ANOVA) for age, body mass index (BMI), operative weight and Chi-square (chi2) test for gender.

RESULTS

There has been a steady increase over the decade in mean patient weight. The operations used have changed from predominantly 'simple' operations to more frequent use of 'complex' operations. Within the categories of 'simple' and 'complex', an increase in the variety of operations occurred. As a group, patients with 'simple' operations have been heavier, more often male and public pay patients than those who have undergone 'complex' operations. One year weight loss was greater for Roux-en-Y gastric bypass (RGB) than vertical banded gastroplasty (VBG), but follow-up rates were too low to study the relative merits of the operations used. The reported incidence of operative mortality and serious complications (leak with peritonitis, abscess and pulmonary embolism) remained low.

CONCLUSIONS

These observations and their implications can be summarized in three statements which relate to action for improved patient care in the beginning of the new century: (1) increasing weight of candidates for surgical treatment during this decade indicates the need for earlier use of operative treatment before irreversible complications of obesity can develop; (2) low risk of obesity surgery, decreasing postoperative hospital stay, and early weight control support the continued and increased use of surgical treatment; (3) continued widespread use of both 'simple' and 'complex' operations with increased modifications of standard RGB and VBG procedures emphasizes the need for standardized long-term data and analyses regarding both weight control and postoperative side-effects.

The role of antioxidant enzymes in the control of opossum sphincter of Oddi motility

Superoxide rapidly oxidizes nitric oxide (NO) to form peroxynitrite, thus terminating the biological activity of NO. The aims of our study were to determine if superoxide alters the motor function of the sphincter of Oddi and to localize the antioxidant enzymes in the sphincter of Oddi. Immunostaining was performed and enzyme activities were measured in the sphincter of Oddi. In physiological experiments, force-displacement transducers recorded tension in the spontaneously contracting sphincter of Oddi and after electrical field stimulation (EFS) of precontracted sphincter of Oddi. Superoxide was generated by the addition of xanthine with xanthine oxidase, superoxide radicals were scavenged by the addition of superoxide dismutase (SOD), and catalase or SOD was inhibited by diethyldithiocarbamic acid. Immunostaining demonstrated SOD and catalase immunoreactivity in ganglia situated at the serosal surface of the circular muscle. Total SOD activity was 202 +/- 12 U/mg. Generation of superoxide or inhibition of SOD increased the contractile frequency and decreased relaxation after EFS. We conclude that superoxide alters sphincter of Oddi motor function, and the presence of superoxide scavenging enzymes in enteric plexuses suggests that they may regulate sphincter of Oddi neuromuscular function by clearing endogenous superoxide.

Endotoxin temporarily impairs canine jejunal absorption of water, electrolytes, and glucose

Enteral feeding during and after episodes of sepsis may be beneficial. The aim of our study was to determine the effects of a single sublethal dose of endotoxin on canine jejunal absorption. Following a 240 kcal liquid meal, absorption studies were performed in eight dogs with 75 cm jejunal Thiry-Vella fistulas. These fistulas were perfused with an isotonic solution containing polyethylene glycol to calculate absorption. Each dog was then given a single dose of Escherichia coli lipopolysaccharide, 200 microg/kg intravenously, and the studies were repeated for the next 3 days. Following endotoxin bolus infusion, net absorption of water, electrolytes, and glucose was decreased for 2 days and returned to baseline values on postendotoxin day 3. A single sublethal dose of endotoxin temporarily impairs canine jejunal absorption. Although enteral feeding may be advantageous, jejunal absorption may be temporarily impaired following an episode of endotoxemia.

Pathophysiology of adynamic ileus

We hypothesized that the inhibitory neurotransmitters nitric oxide (NO) and vasoactive intestinal peptide (VIP) may play a role in the disrupted gastrointestinal motility of endotoxemia. Strain gauge transducers on the stomach and small intestine of dogs determined interdigestive gastrointestinal motility. Tissue levels of NO synthase and VIP and serum levels of nitrite/nitrate (NO(2)-/NO(3)-) and VIP were measured. Following completion of the baseline studies, dogs were given a single dose of E. coli lipopolysaccharide, 200 microg/kg intravenously, and the studies were repeated for the next three days. Following endotoxin bolus, the migrating motor complex (MMC) was delayed for two days while serum VIP was increased on postendotoxin day 1 and serum NO(2)-/NO(3)- was increased on postendotoxin day 2. There were no changes in gut smooth muscle levels of NO synthase or VIP. We conclude that a single, sublethal dose of endotoxin results in prolongation of the MMC with distinct but independent increases in serum levels of VIP and NO(2)-/NO(3)-.

Beyond the hospital walls. Saint Raphael's vision of care includes jobs, home loans, and a reading room

Saint Raphael Health System is based in inner-city New Haven, CT, an area plagued by poverty, unemployment, and high infant mortality. Its leaders have long realized that healthcare involves more than curing diseases and patching wounds. Thus, in 1922, they launched Saint Raphael's Neighborhood Plan, which has five main components. The Neighborhood Reading Room, in a police substation, gives children a place to read, do homework, and get off the streets. The Neighborhood Home Ownership program helps Saint Raphael employees buy homes in the neighborhood. The Neighborhood Scholarships program gives eligible residents an opportunity to study full time at a state university or vocational school. The Neighborhood Career Counseling and Job Skills Assistance program has enabled Saint Raphael to hire 30 neighborhood residents and help others find jobs elsewhere. Reaching beyond its immediate neighborhood, Saint Raphael also operates school-based health centers, clinics for elderly, a mobile clinic for pregnant women and new mothers, a parish nurse program in 21 area churches and congregations, and a home care network. In addition, Saint Raphael is working with the local United Way and other organizations to conduct a community needs assessment; working with Yale University and other organizations to increase neighborhood stability; and operating a program for the early detection of breast and cervical cancer in uninsured and underinsured women.

The effect of ethanol on sphincter of Oddi motility in vitro

Antioxidant enzymes are present in nerves supplying the sphincter of Oddi and regulate its motor function. Oxygen free radicals (O2.-) produce hydrogen peroxide (H2O2) by the action of superoxide dismutase (SOD). Hydroxyl radical (OH.), an important mediator of H2O2 toxicity, oxidizes ETOH. Thus, the aim of our study was determine the effects of ETOH on sphincter of Oddi motility. The sphincter of Oddi was removed from opossums and force transducers recorded tension in its transverse axis. Alcohol (ETOH) was added to the tissue bath in concentrations from 0.1 to 0.4%. OH. was generated by the addition of 0.01% H2O2. Nitric oxide production was inhibited by the addition of 0.3 mM N omega-nitro-L-arginine (L-NNA). H2O2 increased the frequency of sphincter of Oddi contractions. Concentrations of ETOH > 0.3% decreased contractile frequency; however, 0.2% ETOH alone had no affect on the basal frequency of contraction but inhibited the increase in contractile frequency caused by H2O2. L-NNA also increased the contractile frequency; however, this effect was not inhibited by ETOH. We conclude that ETOH attenuates the effect of H2O2 on sphincter of Oddi motility.

The effect of endotoxin on canine jejunal motility and transit

Intestinal transit is rapid during endotoxemia; however, little is known regarding the small intestinal motility changes which produce this rapid intestinal transit. The aim of our study was to determine the degree and duration of disrupted jejunal transit, and changes in jejunal motility following a sublethal dose of endotoxin. Eight dogs underwent construction of jejunal Thiry-Vella fistulas (TVF) with manometry catheters to record motility along the TVF. Following recovery, a 240-kcal liquid meal was given and the TVF was perfused with an isotonic solution. Liquid transit was assessed by bolus of a nonabsorbable marker instilled into the proximal end of the TVF. Recordings of gastrointestinal contractile activity were made digitally to determine postpandial motility. Following completion of the baseline studies, each dog was given a single dose of Escherichia coli lipopolysaccharide (200 micrograms/kg, iv) and the postprandial studies were repeated for the next 3 days. Endotoxin decreased the frequency of jejunal contractions for 2 days while the strength of jejunal contractions was diminished for 1 day. Jejunal transit of liquids was rapid on Postendotoxin Day 1. The rapid transit was associated with a greater percentage of single pressure waves propagating aborally on Postendotoxin Day 1 than the baseline percentages established prior to endotoxin. We conclude that endotoxemia temporarily disrupts postprandial jejunal motility and transit. The rapid liquid intestinal transit seen with endotoxemia may be due to changes in contractile propagation.

Impact of Vertical Banded Gastroplasty on Respiratory Insufficiency of Severe Obesity

BACKGROUND: Respiratory insufficiency associated with morbid obesity can include sleep apnea syndrome (SAS), obesity hypoventilation syndrome (OHS), or a combination of both. The aim of our study was to determine the safety and effectiveness of vertical banded gastroplasty (VBG) in the treatment of severely obese patients with respiratory insufficiency. METHODS: From 1983 to 1994, 35 patients (25 males, ten females) who met the criteria for either SAS and OHS (1 9 patients) or SAS alone (1 6 patients) underwent VBG. RESULTS: Six patients (17%) died of subsequent pulmonary-cardiac disease despite significant weight loss. Need for nasal continuous positive airway pressure (CPAP) decreased after VBG from 68% of patients preoperatively to 22% postoperatively. Of the ten patients with sleep studies, the apnea/hyponea index decreased from 45 +/- 11 events per h preoperatively to 12 +/- 6 events per h postoperatively, while per cent ideal body weight (%IBW) also decreased (pre-VBG: 268 +/- 12, post-VBG: 204 +/- 12). Of the seven patients with arterial blood gases, PaCO&inf2; decreased from 55 +/- 4 torr preoperatively to 41 +/- 3 torr postoperatively, and PaO&inf2; increased from 50 +/- 4 torr preoperatively to 73 +/- 6 torr postoperatively, while %IBW decreased (pre-VBG: 263 +/- 16, post-VBG: 193 +/- 14). CONCLUSION: Respiratory insufficiency is a life-threatening complication of morbid obesity. In morbidly obese patients with respiratory insufficiency, VBG offers improvement in both SAS and OHS. Respiratory insufficiency due to obesity should be considered a strong indication for VBG.

Gastrointestinal myoelectric activity during endotoxemia

BACKGROUND

Gastrointestinal myoelectric activity during postoperative ileus has been well characterized. However, the common clinical scenario of ileus occurring during and after episodes of sepsis is not well understood. The aim of our study was to determine the effects of a single, sublethal dose of endotoxin on canine gastrointestinal myoelectric activity.

METHODS

Eight dogs underwent placement of serosal electrodes on the stomach and small intestine and insertion of a jejunal cannula. After the animals recovered, electrical activity and jejunal mucosal blood flow were determined during fasting and with feeding. Following completion of these baseline studies dogs were given a single, sublethal dose of Escherichia coli lipopolysaccharide (200 g/kg) intravenously, and the studies were repeated daily for 3 consecutive days.

RESULTS

Endotoxin resulted in an absence of the interdigestive migrating myoelectric complex for 2 days, a decrease in duodenal and jejunal action potentials during fasting and with feeding, but no decreases in jejunal mucosal blood flow. The gastrointestinal myoelectrical patterns returned to those found in health on postendotoxin day 3.

CONCLUSIONS

A single, sublethal dose of endotoxin results in a temporary disruption of gastrointestinal myoelectric activity similar to that seen during postoperative ileus. The etiology of this "adynamic" ileus is unknown but does not appear to be secondary to intestinal ischemia.

Pay Status as a Predictor of Outcome in Surgical Treatment of Obesity

BACKGROUND: Higher complication rates and lower success in surgery for severe obesity have been reported for patients with government pay status. We examined the effect of pay status upon outcome in surgical treatment of obesity. METHODS: This was an observational study from an aggregate data set of individual patient information. Government pay status (G) was defined as full or partial medical care payment through Medicare, Medicaid, or Veterans Administration. Payment entirely by private insurance was defined as private (P). Operations were classified as either simple (S, gastric restriction) or complex (C, gastric restriction with small bowel bypass). Two measures of outcome, perioperative complication rate and weight loss success (</= 50% excess weight), were examined to determine pay status effect. RESULTS: More G than P patients were treated with simple procedures (79% vs 51%, p < 0.05). Perioperative complication rates were more common for G than P patients (14.4% vs 9.1%, p < 0.05). One-year weight loss success was higher for P than G, regardless of operation type. CONCLUSION: Pay status should be included in characterization of patient groups and in the analysis of results when effectiveness of surgical treatment for severe obesity is reported.

Functional characteristics of canine pylorus in health, with pyloroplasty, and after pyloric reconstruction

The aim was to determine whether pyloroplasty decreases the strength of pyloric contractions and speeds gastric emptying of solids, while subsequent pyloric reconstruction restores these abnormalities to the control. In conscious dogs, pyloroplasty decreased the strength of pyloroduodenal pressure waves measured with a perfused sleeve sensor [mean +/- SEM pyloroduodenal motility index: control (N = 7) = 1116 +/- 351 mm Hg x sec/10 min; pyloroplasty (N = 7) = 43 +/- 19 mm Hg x sec/10 min; P < 0.05], and caused rapid gastric emptying of solids measured scintigraphically (mean +/- SEM half-emptying time: control = 246 +/- 14 min, pyloroplasty = 176 +/- 16 min; P < 0.05). The frequencies of pyloroduodenal waves and gastric emptying of liquids, however, were unchanged. Pyloric reconstruction restored the postpyloroplasty patterns to the control. In conclusion, pyloroplasty decreased the strength of pyloroduodenal contractions and sped gastric emptying of solids, while pyloric reconstruction restored the altered patterns to the control.

Gastrointestinal transit during endotoxemia: the role of nitric oxide

We hypothesized that the disrupted gastrointestinal transit that occurs during endotoxemia is mediated by nitric oxide (NO) and that the inhibition of NO synthesis will normalize intestinal transit and gastric emptying. To determine the effects of endotoxin and steroids on the activity of gastrointestinal smooth muscle NO synthase, rats underwent placement of an intravenous (iv) line and then were given Escherichia coli lipopolysaccharide (LPS) 10 mg/kg/iv; LPS, 10 mg/kg/iv + dexamethasone, 3 mg/kg/iv; or saline. The activity of nitric oxide synthase in the stomach, small intestine, and colon were determined by measuring the conversion of L-[3H]arginine to L-[3H]citrulline. To determine intestinal transit and gastric emptying, gavage feedings of nonabsorbable liquid markers were given and rats divided into eight groups: 0.9% NaCl, 1 ml/hr x 5 hr (control); LPS, 10 mg/kg/iv; LPS + N-omega-nitro-L-arginine methyl ester (L-NAME), 10 mg/kg/hr x 5 hr; LPS + N-omega-nitro-D-arginine methyl ester (D-NAME), 10 mg/kg/hr x 5 hr; LPS + L-arginine, 100 mg/kg/hr x 5 hr; LPS + L+NAME + L-arginine; LPS + N-omega-nitro-L-arginine (L-NNA) 10 mg/kg/hr; or LPS + L-NNA + L-arginine. LPS increased the enzymatic activity of both the constitutive and the inducible forms of NO synthase in the small intestine and fundus of the stomach. The acceleration of intestinal transit produced by endotoxemia was reversed with both L-NAME and L-NNA but not with D-NAME. Endotoxemia slowed gastric emptying but this effect was not reversed with either L-NAME or L-NNA. We conclude that NO plays a major role in mediating the rapid intestinal transit during endotoxemia.

Effects of recombinant human hemoglobin on opossum sphincter of Oddi motor function in vivo and in vitro

Nitric oxide (NO) acts as a nonadrenergic, noncholinergic inhibitor neurotransmitter that regulates sphincter of Oddi (SO) motor function. Hemoglobin blocks NO activity by binding it after it is synthesized. We hypothesized that recombinant human hemoglobin (rHb1.1) affects SO motor function by scavenging NO. Under anesthesia, 12 opossums underwent biliary tract manometry. Following a stabilization period, six animals were given rHb1.1 (0.28 g/kg over 30 min), while six received bovine albumin (0.28 g/kg over 30 min). Recordings were made during the infusion and for 3 hr after the infusion. In an in vitro preparation, force transducers were used to record spontaneous contractions at two sites along the sphincter segment. After a control period, rHb1.1 (0.1 mM) or cyanomethemoglobin (0.1 mM) was added to the tissue bath and recordings continued for another 2 hr. Recombinant human hemoglobin decreased the frequency of contractions, increased resting tone, and blocked the relaxation phase of contraction in vivo. It increased the baseline amplitude, the frequency, and the peak amplitudes of contractions in vitro. Albumin or cyanomethoglobin, which are unable to bind NO, had little effect on SO motor activity. We conclude that rHb1.1 may alter SO motor function by binding endogenous NO.

The management of extrahepatic portal vein aneurysms: observe or treat?

A case of a 70 year old man who was found to have an extrahepatic portal vein aneurysm during an evaluation for hematuria is reported. Extrahepatic portal vein aneurysms are rare with only twenty cases reported in the literature. Typically, patients present with hemorrhage requiring surgical exploration or the aneurysm is discovered during evaluation of another abdominal process. Management includes careful follow-up in the asymptomatic patient without underlying liver disease or portal hypertension.

Reversal of small intestinal bypass operations and concomitant vertical banded gastroplasty: long-term outcome

BACKGROUND

Long-term complications of jejunoileal bypass (JIB) have been reported, prompting restoration of intestinal continuity and concomitant performance of vertical banded gastroplasty (VBG) for weight control. The aim of this study was to evaluate the presentation and reversal of JIB complications, late complications, mortality, and long-term weight control in patients who have undergone JIB reversal and concomitant VBG.

STUDY DESIGN

From 1981 to 1994, 37 patients were treated for complications from JIB that included diarrhea (73 percent), arthritis (46 percent), malnutrition (22 percent), urolithiasis (19 percent), electrolyte disorders (19 percent), and lack of weight loss (8 percent). Four patients required preoperative parenteral nutrition to correct protein and electrolyte imbalances. Surgical management of all 37 patients included restoration of bowel continuity and VBG during the same operative procedure.

RESULTS

Postoperative complications occurred in 11 patients, including prolonged ileus in seven patients, pancreatitis in three patients, and infectious complications in two. There were no deaths. Late morbidity included staple line dehiscence in four patients, incisional hernia in three patients, and reversal of the VBG in one. All patients with diarrhea, malnutrition, electrolyte disorders, and lack of weight loss had resolution of their symptoms, while urolithiasis and arthritis resolved in 86 and 53 percent of patients, respectively. In patients available for five-year follow-up evaluation, weight changes were small, shifting from a preoperative weight of 87 +/- 19 to 90 +/- 19 kg at five years (mean +/- SD).

CONCLUSIONS

Restoration of intestinal continuity combined with VBG is a safe and effective operation that will reverse most of the long-term complications of JIB and provide stable weight control for up to five years.

The Effect of Follow-up on Reporting Success for Obesity Surgery

BACKGROUND: Much is written about the importance of follow-up in determining the effect of surgical treatment for obesity upon weight loss. When patients are lost to follow-up, it has been suggested that these patients should be considered as failures. This study was undertaken to determine the effect of incorporating patients not followed in a definition of success for weight loss at one year. METHODS: Data from 34 surgical practices were used to study the effect of using two different denominators, patients followed (Df) or patients eligible (De), to define success. The numerator used in both methods was the number of patients with </= 50% EW at 1 year. RESULTS: One-year follow-up was 61% (5091/8356). Success was 67% (3423/5091) when calculated using the denominator patients followed (Df). No correlation was found between success and follow-up when data within each surgical practice were averaged and used in a correlation analysis. CONCLUSIONS: This study does not support the thesis that patients who fall to return for follow-up should be considered as having failed in weight control.

Ectopic jejunal pacemakers after jejunal transection and their relationship to transit

The hypothesis was that orally moving pacesetter potentials distal to a site of jejunal transection and anastomosis would slow transit through jejunum containing them and that reoperation with excision of bowel containing these pacesetter potentials would restore transit to the control. In six conscious dogs with jejunal serosal electrodes for recording myoelectric activity and a jejunal perfusion/aspiration catheter for measuring transit, jejunal pacesetter potential frequency decreased distal to a midjejunal transection and anastomosis from 18.7 +/- 0.3 (SE) cycles/min (cpm) proximal to the site to 14.4 +/- 0.6 cpm distal to the site (P < 0.05). In addition, orally propagating pacesetter potentials occurred > 25% of the time in a 37 +/- 7 cm length of bowel distal to the site during fasting and after feeding. Transit through the segment with the orally moving pacesetter potentials was slowed during feeding (half time before and after transection, 7.7 +/- 1.1 and 13 +/- 2.0 min, respectively, P < 0.05). Resection of the segment with the abnormal pacesetter potentials shortened the length of bowel containing them to 24 +/- 2 cm (P > 0.05) and restored transit to the control. In conclusion, orally moving pacesetter potentials distal to a canine jejunal transection and anastomosis slowed transit through the segment of bowel containing them. Resection of the segment restored transit to the control.

Vertical Banded Gastroplasty in the Severely Obese under Age Twenty-One

BACKGROUND: The severely obese under 21 years of age are at high risk of missing normal development during a crucial period of life and should be considered for surgical treatment. Vertical banded gastroplasty allows patients to be treated effectively while continuing to have normal digestion and absorption without the risks of complex operations. METHODS: This was a retrospective outcome review of 47 severely obese who were under age 21 when surgically treated with VBG. RESULTS: There were no operative mortalities, leaks, or wound infections. Body mass index in 25 patients followed 5 years decreased from an average operative 48.1 to 36.2 kg m(2). Equally for 14 patients followed 10 years, BMI decreased from an average operative 49.6 to 39.2 kg m (2). Both patient groups had 74% follow-up. CONCLUSIONS: Sustained weight reduction improved general health and allowed participation in life activities that would otherwise not have been possible. Adherence to recommended operative technique and intraoperative measurement of pouch volume is necessary to avoid excessive enlargement of the pouch, with resulting weight gain, reflux, and need for revision.

Tonic responses of canine proximal colon: effects of eating, nutrients, and simulated diarrhea

Our hypothesis was that the proximal colon relaxes to accommodate flow from the ileum. Therefore, we recorded tonic responses of the canine proximal colon to flow through the ileum and colon stimulated by 1) an 840-kcal meal, 2) nutrients perfused into the ileum and colon, or 3) rapid infusion of saline into the ileum with overflow into the colon. Saline infusion was considered to be a model of diarrhea, and the effects of an antidiarrheal (morphine sulfate) were therefore assessed. Proximal colonic tone was measured with a barostat. Tone increased before and after the arrival of chyme in the ileocolonic region. Perfusion of nutrients into the ileum and colon also significantly increased (P < 0.05) colonic tone compared with equal volumes of saline. Rapid perfusion of the ileocolonic segment with saline increased colonic tone; this increase was significantly greater (P < 0.01) when preceded by morphine. In contrast to our hypothesis, tone of the canine proximal colon increased in response to ileal flow. The increase in colonic tone during the late response to food was at least partly attributable to stimulation by intraluminal contents.

Epidural analgesia shortens postoperative ileus after ileal pouch-anal canal anastomosis

PURPOSE

A retrospective study was conducted to determine whether epidural analgesia would speed recovery from postoperative ileus in patients undergoing ileal pouch-anal canal anastomosis.

METHODS

Among 85 patients who underwent proctocolectomy with ileal pouch-anal canal anastomosis at the Mayo Medical Center between January 1, 1991 and October 31, 1992, 44 were treated for postoperative pain with continuous infusion of epidural fentanyl citrate supplemented by intravenous morphine on request, while 41 controls were given only systemic morphine sulfate as needed.

RESULTS

The patients in the two groups were matched and similar with regard to preoperative and operative risk factors and postoperative morbidity. No operative mortality occurred. Epidural fentanyl analgesia resulted in less need for nasogastric suction and intravenous fluids, more rapid discharge of fecal content, more rapid return to oral intake, and shorter hospitalization.

CONCLUSION

Epidural analgesia with fentanyl citrate shortened postoperative ileus after proctocolectomy and ileal pouch-anal canal anastomosis.

Effect of endotoxin on canine gastrointestinal motility and transit

Ileus is common during sepsis; however, the etiology of this gastrointestinal dysmotility is unclear. The aim of our study was to determine the effects of a single, sublethal dose of endotoxin on canine gastrointestinal motility, gastric emptying, gastric acid secretion, and colonic transit. Six dogs underwent placement of manometric catheters in the stomach and small bowel and insertion of a gastric and a cecal cannula. After the animals recovered, fasting and fed gastrointestinal motility was recorded, and gastric emptying and colonic transit were studied with nonabsorbable liquid and solid markers, respectively. Following completion of baseline studies, each dog was given a single dose of Escherichia coli lipopolysaccharide (200 micrograms/kg intravenously) and the studies were repeated on Postendotoxin Days 1-3. The single bolus of endotoxin abolished the migrating motor complexes, decreased the fasting motility index, decreased hydrogen ion output, slowed liquid gastric emptying, and prolonged colonic transit for 2 days. Gastrointestinal motility and transit returned to baseline on Postendotoxin Day 3. In conclusion, a single, sublethal dose of endotoxin temporarily disrupts fasting and postprandial canine gastrointestinal motility and transit.