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Gallbladder absorption is increased prior to gallstone formation in prairie dogs and may promote cholesterol crystallization. Recent studies indicate that Ca2+-calmodulin (CaM) tonically inhibits gallbladder electrolyte absorption in prairie dogs fed a nonlithogenic diet. We hypothesized that dietary cholesterol alters CaM-dependent regulation of gallbladder ion transport, a possible link between increased gallbladder absorption and gallstone formation. Gallbladders from prairie dogs fed control (N = 24) or 1.2% cholesterol-enriched chow (N = 32) were mounted in Ussing chambers. Electrophysiology and ion flux were measured while exposing the epithelia sequentially to trifluoperazine (TFP), a CaM antagonist, followed by the calcium ionophore A23187. Animals fed the high cholesterol diet developed crystals and gallstones in a time-dependent fashion. Mucosal addition of 50 microM TFP decreased short-circuit current (Isc), transepithelial potential, and tissue conductance in control, crystal, and gallstone animals, but the magnitude of its effect was significantly decreased in animals fed cholesterol. TFP stimulated mucosa-to-serosa Na+ flux by 6.9 +/- 0.9 microeq/cm2/hr in control animals but only 3.1 +/- 0.8 microeq/cm2/hr in gallstone animals. Similarly, TFP increased mucosa-to-serosa Cl- flux by 11.9 +/- 1.4 microeq/cm2/hr in controls but only 4.9 +/- 1.4 microeq/cm2/hr in cholesterol-fed animals. TFP effects were not reversed by A23187, which caused differential effects on Isc and ion transport in cholesterol-fed animals. In conclusion, CaM-mediated inhibition of gallbladder Na+ and Cl- transport is diminished in prairie dogs fed cholesterol. We conclude that gallbladder ion transport is partially released from basal inhibition during gallstone formation and propose that dysfunctional CaM regulation may be a stimulus to increased gallbladder absorption.

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In addition to concentrating bile, the gallbladder secretes chloride (Cl-) and mucus into its lumen. We recently observed that gallbladder Cl- secretion is increased in prairie dogs during the formation of cholesterol crystals, a period of altered mucosal prostaglandin synthesis. Pathologic Cl- secretion is characteristic of other epithelial disorders such as cystic fibrosis and hypercalciuric nephrolithiasis and may be important in gallstone pathogenesis. We hypothesized that concentrations of endogenous prostaglandin E2 (PGE2) found during experimental gallstone formation may mediate increased Cl- secretion by prairie dog gallbladder. Prairie dog gallbladders were harvested by cholecystectomy and mounted in Ussing chambers. Unidirectional transepithelial Cl-, Na+, and H20 fluxes were measured before and after inhibition of endogenous prostaglandin synthesis with 10 micromol/L indomethacin. Gallbladders were then exposed to increasing concentrations of PGE2 to a maximal dose of 1 micromol/L, as found in animals with gallstones. Standard electrophysiologic parameters were recorded simultaneously. Indomethacin increased mucosal resistance and stimulated gallbladder Na+ and Cl- absorption. These effects were rapidly reversed by PGE2. PGE2 promoted Cl- secretion and decreased mucosal Na+ absorption at concentrations found in the gallbladder bile of animals with gallstones. Endogenous prostaglandin metabolism modulates gallbladder Cl- secretion and may promote changes in Cl- transport associated with cholelithiasis.

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BACKGROUND: Gallstone formation during octreotide therapy has been linked to elevated levels of gallbladder bile Ca++, a well-known prolithogenic factor. Although the subcutaneous administration of octreotide raises gallbladder bile Ca++ in prairie dogs, the mechanism for this effect is unknown. Octreotide has been shown to increase gallbladder Na+ and water absorption in Ussing chamber studies. Given the known effects of octreotide on gallbladder ion transport, we hypothesized that octreotide may also promote gallstone formation by stimulating gallbladder Ca++ secretion, thereby raising the lumenal concentration of biliary Ca++. METHODS: After cholecystectomy, prairie dog gallbladders were mounted in Ussing chambers, and standard electrophysiologic parameters were recorded. Unidirectional fluxes of Ca++ and Na+ were measured before and after serosal exposure to 50 nmol/L octreotide. RESULTS: Under basal conditions normal prairie dog gallbladder absorbed mucosal Ca++. Serosal octreotide converted the gallbladder from a state of basal Ca++ absorption to one of net Ca++ secretion by stimulating serosa to mucosa Ca++ flux. As anticipated, octreotide increased net Na+ absorption by stimulating mucosa to serosa Na+ flux and decreased tissue conductance and short-circuit current significantly compared with baseline values. CONCLUSION: Fifty nanomoles per liter octreotide stimulated Ca++ secretion by gallbladder epithelium, a possible mechanism for increased biliary Ca++ in prairie dogs receiving subcutaneous injections. Ca++ secretion linked to octreotide therapy may induce gallstones by raising biliary levels of Ca++, a known prolithogenic factor.

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This article describes how the surgery clerkship at MCP Hahnemann School of Medicine was redesigned to provide all students a well-rounded general professional education and to address the specific educational needs of generalists. During the 12-week clerkship, students spend eight weeks on two different general surgery rotations, which include significant experiences in outpatient settings. The evaluation and management of common general surgical problems, as well as the holistic approach to patient care, are emphasized. A nurse educator, recruited through funding obtained from The Robert Wood Johnson Foundation's Generalist Physician Initiative, provides formal instruction in holistic care and teaches bedside procedures. Two weeks are devoted to focused surgical subspecialty experiences addressing common conditions and are conducted primarily in outpatient settings. The remaining two weeks include an integrated musculoskeletal disease rotation, including orthopaedic surgery, rheumatology, physiatry, and radiology. Didactic teaching includes criteria for referral of patients from generalists to specialists. The new clerkship model has been well received by the students. Review of student logs for the first six months indicates the breadth of surgical experience has been maintained and appropriate balance achieved between simple and complex surgical cases. Further evaluation of the model will continue through longitudinal follow-up.

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Hepatic bile synthesis is altered during experimental gallstone formation. In response to cholesterol, there is a hydrophobic shift in hepatic bile acid synthesis and hypersecretion of phospholipids. These changes decrease the vesicular capacity for cholesterol and favor crystallization. The mechanism for these changes in hepatic bile formation is unknown. Calmodulin (CaM), a Ca2+ receptor protein involved in cellular secretion, regulates gallbladder transport and may play an important role in alterations of hepatic bile formation during cholelithiasis. We hypothesized that biliary CaM activity is altered during gallstone formation and may be associated with changes in bile acid and phospholipid synthesis. Prairie dogs were fed either control (N = 22) or 1.2% cholesterol-enriched (N = 26) diets for one to six weeks. Cholecystectomy was performed; the common bile duct was cannulated, and hourly bile samples were collected. CaM was measured in bile and gallbladder tissues by radioimmunoassay. Bile samples were analyzed for cholesterol, phospholipids, total bile acids, total protein, calcium, and individual bile acid composition. Compared to controls, gallstone animals had elevated hepatic bile levels of CaM, phospholipids, and cholesterol. Hydrophobic bile acid synthesis was also stimulated, with increased levels of taurochenodeoxycholic acid (TCDCA) and decreased taurocholic acid (TCA). Gallbladder bile demonstrated similar changes. Although gallbladder bile CaM levels were increased, tissue levels were unchanged, suggesting that increased CaM concentration is a hepatic phenomenon. Hepatic bile CaM activity correlated linearly with TCDCA concentration (r = 0.64, P < 0.004) and phospholipid hypersecretion (r = 0.53, P < 0.03). The relationship between biliary CaM and increased concentrations of TCDCA and phospholipids suggests a role for CaM in alterations of hepatocyte secretion that may promote gallstone formation.

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OBJECTIVE: This study sought to correlate gallbladder (GB) Na+ and Cl-) fluxes with biliary lipid composition during the various stages of gallstone (GS) formation. SUMMARY BACKGROUND DATA: GS formation is associated with altered GB ion transport and increased biliary lipid and Ca2+ concentrations. Nonetheless, the longitudinal relationship between ion transport and biliary lipid changes during GS formation has not been defined. METHODS: Prairie dogs were fed standard (n = 18) or 1.2% cholesterol-enriched (n = 30) diets for 4 to 21 days. Hepatic and GB bile were analyzed for lipids and Ca2+. Animals were designated either Pre-Crystal, Crystal, or GS based on absence or presence of crystals or GS, respectively. GBs were mounted in Ussing chambers, electrophysiologic parameters were recorded, and unidirectional Na+ and Cl- fluxes measured. RESULTS: Short-circuit current and potential difference were similar during Pre-Crystal and Crystal stages but significantly reduced during GS stage compared to controls and Pre-Crystals. Transepithelial resistance was similar in all groups. Net Na+ absorption was increased during Pre-Crystal but decreased during GS stage due to increased mucosa-to-serosa and serosa-to-mucosa flux, respectively. Increased serosa-to-mucosa flux of both Na+ and Cl- characterized the Crystal stage. Biliary lipids and Ca2+ increased progressively during various stages of GS formation and correlated positively with unidirectional fluxes of Na+ and Cl-. CONCLUSION: GB epithelial ion transport changes sequentially during GS formation, with the early Pre-Crystal stage characterized by increased Na+ absorption, and the later Crystal stage accompanied by prosecretory stimuli on Na+ and Cl- fluxes, which may be due to elevated GB bile Ca2+ and total bile acids.

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Cancer surgery is safe for older patients and should not be denied on the basis of chronological age. The curability of cancer in the elderly is predicated on the individual's tolerance of major surgery. We present the physiologic changes that occur with aging and focus on their influence upon surgical decision making, the risk factors associated with cancer surgery in the elderly, the preoperative assessment, and perioperative care of the elderly cancer patient, as well as surgical considerations for specific neoplasms.

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The development of sepsis associated with a GI fistula can be a catastrophic complication of any surgical procedure in the vicinity of the abdominal cavity. The predominant sites of infection directly associated with GI fistulas are in the surgical wound and within the abdominal cavity. Some patients present with florid signs of sepsis, whereas others may have minimal signs of infection. CT scanning is the main diagnostic method for intra-abdominal collections. Often, it also provides a means of treatment by percutaneous placement of catheters. Patients who develop extensive cellulitis or necrotizing fasciitis, intra-abdominal collections incompletely drained by percutaneously placed catheters, multiple intra-abdominal collections not amenable to percutaneous drainage, dissociation of the ends of an anastomosis with flow of enteric contents into the peritoneal cavity, large intra-abdominal hematoma, or a septic course without identifiable source should be taken to the operating room on an urgent basis. The operative approach varies with the particular situation and extends from incision and drainage of the wound, extraperitoneal drainage of an abscess, and formal exploratory laparotomies, to the placement of tube enterostomies for decompression and drainage. The overall mortality of fistulas has decreased owing to better fluid and electrolyte replacement and the proper use of parenteral nutrition. However, patients continue to die from fistulas, and the cause of death is nearly always infection. The burden is on the surgeon to expeditiously diagnose and treat sepsis associated with GI fistulas.

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Gallstone disease continues to be one of the more common abdominal problems that prompts medical evaluation, particularly in the elderly population. The presentation is diverse, and the treatment options varied. Primary care physicians need to be familiar with the differential diagnosis, evaluation, and therapeutic options available. LC has emerged as the preferred treatment for patients with symptomatic gallstone disease.

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Gallstone formation is associated with altered gallbladder (GB) ion transport and increased concentration of GB bile Ca2+. Recent studies show that increased cytosolic Ca2+ ([Ca2+]i) stimulates GB Cl- secretion. However, the mechanism by which extracellular Ca2+ ([Ca2+]e) enters the cytosol remains unclear. We tested the hypothesis that entry of [Ca2+] into cytosol occurs via apical and basolateral membrane Ca2+ channels. Prairie dog GBs were mounted in Ussing chambers, standard electrophysiologic parameters were recorded, and unidirectional Cl- fluxes (J, microEq x cm(-2) x hr(-1) were measured using 36Cl at various mucosal Ca2+ in the absence or presence of mucosal lanthanum (La3+), a non-diffusible Ca2+ channel blocker. Serosal [Ca2+]e was maintained at trace levels. In the absence of mucosal La3+, short circuit current (Isc) showed a positive correlation with mucosal [Ca2+]e as represented by a second order polynomial equation (y = 4.1 + 2.5x - 0.73x(2), r = 0.68, P < 0.001). In contrast, unidirectional mucosa to serosa Cl flux (JCl/ms) was inversely correlated with [Ca2+] (y = 47.9 - 8.7x + 0.9x(2), r = 0.51, P <.05) Addition of 1 mM mucosal La3+ blunted the effects of [Ca2+]e on electrophysiologic parameters and JCl/ms. However, basolateral repletion with 5 mM Ca2+ reverses the blocking effects of La3+ on JCl/ms. These data suggest that [Ca2+]e enters the cytosol via apical and basolateral Ca2+ channels. We conclude that GB apical Ca2+ channels may represent a pathway for biliary Ca2+ entry into the cell and therefore may represent an important regulatory pathway for GB ion transport during gallstone formation.

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BACKGROUND: Experimental cholelithiasis is associated with elevated biliary calcium concentration and altered gallbladder absorption. Recent studies showed that extracellular calcium ([Ca2+]ec) plays a role in regulating gallbladder ion transport. The extent to which intracellular calcium ([Ca2+]ic) mediates the changes in gallbladder ion transport is not clear. We hypothesize that [Ca2+]ic is an important regulator of gallbladder ion transport. METHODS: Prairie dog gallbladders were mounted in Ussing chambers, standard electrophysiologic parameters were recorded, and unidirectional Na+, Cl- and H2O fluxes were measured before and after mucosal exposure of 10-5 mol/L calcium ionophore A23187 was performed. RESULTS: A23187 caused an increase in transepithelial short-circuit current and potential difference and a decrease in transepithelial resistance. A23187 inhibited mucosa to serosa Cl- flux and stimulated serosa to mucosa Na+ flux, resulting in increased net Cl- secretion and decreased net Na+ absorption. A23187 converted H2O from absorption to secretion. Transepithelial short-circuit current effect of A23187 was delayed by indomethacin pretreatment and was completely blunted by low bathing Ca2+. CONCLUSIONS: This is the first demonstration that increased [Ca2+]ic converts the gallbladder from its normal absorptive state to a secretory one. Furthermore [Ca2+]ic appears to regulate ion transport through mechanisms that are partially prostaglandin-dependent. Studies are necessitated to define possible links between gallbladder secretion of Cl- and H2O and mucus hypersecretion, a well-described phenomenon associated with cholesterol gallstone formation.

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BACKGROUND: Residents may have significant differences in clinical skills at the start of their surgical training. The purpose of this study was to investigate the variability in these skills by using an objective structured clinical examination. METHODS: A needs assessment was performed, and an objective structured clinical examination composed of 10, two-part stations was developed. Standardized patients (SPs) were trained, validated, and used as both simulated patients and evaluators to assess history taking, physical examination, and interpersonal skills of 10 first-year surgical residents. Structured patient notes (PNs) written by residents after the SP encounters were used to assess history and physical examination documentation skills. Data from one station were not used because more than 25% of the SP ratings were missing. RESULTS: The alpha-reliability was 0.78 for SP ratings, 0.91 for PN scores, and 0.91 for the combined scores. ANOVA revealed significant variation in individual residents' clinical skills as assessed by SPs (F = 4.56, p < 0.01), PNs (F = 11.09, p < 0.001), or both (F = 10.9, p < 0.001). Paired t tests showed that residents scored significantly higher on history taking than on physical examination and attained significantly lower scores on documentation as compared with performance of both history and physical examination (p < 0.001 for each comparison). CONCLUSIONS: The results showed significant variability in clinical skills of the group of residents and yielded detailed information on the performance of each resident. The data were shared with individual residents and are being used to make changes in the educational activities of the program.

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BACKGROUND/AIMS: Gallstone formation during octreotide administration has been causally linked to increased biliary concentrations of calcium, protein, and total lipids, all purported prolithogenic factors. These changes may be caused by octreotide-induced gallbladder stasis or a direct effect of octreotide on gallbladder absorption. We tested the hypothesis that octreotide stimulates gallbladder ion and water transport. METHODS: Prairie dog gallbladders were mounted in Ussing chambers and bathed in oxygenated Ringer's solution. Electrophysiological parameters were recorded, and unidirectional Na+, Cl-, and H2O fluxes were measured before and after serosal exposure to 50 nmol/L octreotide. RESULTS: Octreotide exposure caused a significant decrease in transepithelial short-circuit current and potential difference and an increase in tissue resistance compared with baseline. These alterations in electrophysiological parameters coincided with changes in ion transport. Octreotide stimulated net Na+ and H2O absorption and converted the gallbladder from a state of Cl- secretion to one of Cl- absorption by increasing mucosal to serosal fluxes. Octreotide effects on ion transport were blocked by 4,4'-diisothiocynostilbene-2,2'-disulfonic acid and amiloride and reversed by theophylline. CONCLUSIONS: Octreotide may promote gallstone formation by inducing gallbladder stasis and by directly increasing gallbladder absorption, which may act synergistically to increase the concentration of prolithogenic factors in bile and to facilitate nucleation and stone growth.

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BACKGROUND: Gallstone formation is characterized by increased biliary calcium (Ca2+) level and altered gallbladder absorption. Recent studies suggest that luminal Ca2+ regulates gallbladder ion transport via intracellular calcium ([Ca2+]ic). Ca2+-calmodulin and protein kinase C (PKC) are two major systems through which [Ca2+]ic carries out second-messenger functions in many cell types. We have previously shown that Ca2+-calmodulin regulates basal gallbladder ion transport in prairie dog. The present study tests the hypothesis that PKC is also essential in regulation of gallbladder ion transport in this model. METHODS: The role of PKC in regulation of gallbladder ion transport was determined by studying the effects of phorbol esters, synthetic analogues of diacylglycerol, which directly activates PKC. Gallbladders were mounted in Ussing chambers, and standard electrophysiologic parameters were recorded after exposing tissues to either 10(-5) mol/L of 4-alpha-phorbol 12,13-didecanoate (PDD), 4-beta-phorbol 12-myristate 13-acetate, 4-beta-phorbol 12,13-dibutyrate (PDB), or 10(-4) mol/L serotonin. Unidirectional Na+, Cl-, and H2O fluxes were measured before and after treatment with only inactive PDD and most active PDB. RESULTS: Mucosal and serosal exposure of tissues to either 4-beta-phorbol 12-myristate 13-acetate or PDB resulted in a decrease in short-circuit current and transepithelial potential difference without any change in tissue resistance. Serotonin induced similar changes in gallbladder electrical properties. PDB caused an inhibition of mucosal to serosal fluxes of Na+, Cl-, and H2O, with a decrease in net Na+ absorption, an increase in net Cl- secretion, and a conversion of net H2O absorption to net H2O secretion. Serosal-to-mucosal fluxes of Na+, Cl-, and H2O did not change. Inactive PDD had no effect on either electrophysiologic parameters or ion and water fluxes. Pretreatment of tissues with PKC antagonist 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine blocked the phorbol ester-induced inhibition of ion transport. CONCLUSION: PKC regulates gallbladder ion transport in the prairie dog by inhibiting Na+ absorption and stimulating Cl- secretion.

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Surgery continues to play an important role in the overall treatment strategy for patients with Crohn's disease and ulcerative colitis. Innovative techniques have greatly facilitated the operative approach in patients with both disorders.

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We reviewed the records of 32 adult patients with choledochal cysts (CDC) to determine the characteristics of the associated pancreatic disease. Eighteen patients (56%) had 30 documented episodes of pancreatitis with epigastric pain and elevated serum amylase levels. Three patients developed a prolonged course with a pancreatic phlegmon and one patient died secondary to a pancreatic abscess after endoscopic retrograde cholangiopancreatography (ERCP). Pancreatitis occurred in all types of CDC and was not related to the age, gender or race of the patient. There was an association with the size of the CDC: 90% of patients with CDC > or = 5 cm developed pancreatitis compared with only 9% of patients with CDC < 5 cm (p < 0.0004). In addition, ERCP was performed in 14 patients and demonstrated an abnormal pancreaticobiliary duct junction in eight (57%). All eight patients with an abnormal pancreaticobiliary junction developed pancreatitis compared with only 2 out of 6 patients with normal pancreatic duct anatomy (p < 0.006). Patients undergoing surgical bypass rather than resection also tended to have higher rates of pancreatitis (80 vs. 50%). One patient with a Type I CDC and chronic pancreatitis was treated with surgical resection of the CDC and pancreatic head; this combined procedure relieved the pain. Microscopic examination of the CDC and the abnormal "common channel" within the pancreas revealed identical fibrous thickening of the duct walls with focal chronic inflammation and loss of surface epithelium. In conclusion, these data stress the previously unrecognized high incidence of symptomatic pancreatic inflammatory disease that accompanies adult CDC.(ABSTRACT TRUNCATED AT 250 WORDS)

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Although nucleation is critical to the pathogenesis of cholesterol gallstones, the factors responsible for this process are poorly defined. Numerous potential nucleating agents have been identified in the bile of humans and animals with cholelithiasis, including mucus, calcium, and bilirubin. Recent studies have shown that patients with cholesterol crystals and gallstones have increased biliary total protein, suggesting that protein may be a previously unrecognized nucleating factor. We tested the hypothesis that biliary total protein is increased prior to cholesterol gallstone formation. Prairie dogs were maintained on either control (N = 22) or 0.4% cholesterol-enriched chow (N = 18) for up to 18 weeks. Cholesterol-fed animals were classified as pregallstone (N = 12) or gallstone (N = 6) based on gross examination of the gallbladder bile. Both hepatic and gallbladder biles were then analyzed for lipid, bile acid, calcium, and protein content. Cholesterol feeding was associated with increased gallbladder concentrations of cholesterol, phospholipids, and calcium in the pregallstone and gallstone groups. Biliary total protein was significantly elevated in the pregallstone (5.8 +/- 0.4 mg/ml, P < 0.001) and gallstone animals (6.0 +/- 0.6 mg/ml, P < 0.001) as computed to controls (3.8 +/- 0.3 mg/ml). Regression analysis showed positive correlations between gallbladder bile total protein and the gallbladder bile cholesterol saturation index (CSI) (P < 0.001), as well as between gallbladder total protein and calcium (P < 0.001). Although the hepatic bile CSI was elevated in cholesterol-fed animals, total protein remained unchanged, suggesting that the alteration in biliary protein is a gallbladder phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)

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Hepatobiliary disease is the most common reason for abdominal surgery in the elderly population. Therefore, familiarity with these diseases as they occur in geriatric patients has become increasingly important. This article reviews hepatobiliary disease with a specific emphasis on issues that affect the treatment of the elderly. Although the focus of this review is primarily clinical, pertinent experimental findings have been included.

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