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ABSTRACT: Glucagon-like peptide-1 (GLP-1) receptors are highly overexpressed in benign insulinomas, permitting in vivo tumour visualisation with GLP-1 receptor scanning. The present study sought to evaluate the GLP-1 receptor status in vitro in other pancreatic disorders leading to hyperinsulinaemic hypoglycaemia, specifically after gastric bypass surgery.
Fresh frozen pancreatic tissue samples (n=7) from six gastric bypass surgery patients suffering from hyperinsulinaemic hypoglycaemia were evaluated for GLP-1 receptor content using in vitro receptor autoradiography, and compared with normal pancreas and with pancreatic insulinoma tissues.
GLP-1 receptor analysis of the pancreatic tissues, which histopathologically were compatible with nesidioblastosis and originated from post-bypass hypoglycaemic patients, revealed a mean density value of GLP-1 receptors in the islets of 1,483 ± 183 dpm/mg tissue. Pharmacological characterisation indicated the presence of specific GLP-1 receptors. The density of islet GLP-1 receptor in post-gastric bypass patients did not differ from that of normal pancreas (1,563 ± 104 dpm/mg tissue, n = 10). Receptor density in pancreatic acini was low in post-bypass and control conditions. In contrast, benign insulinomas showed a high density of GLP-1 receptors, with a mean value of 8,302 ± 1,073 dpm/mg tissue (n = 6).
In contrast to insulinoma, hyperinsulinaemic hypoglycaemia after gastric bypass surgery is not accompanied by overexpression of GLP-1 receptor in individual islets. Thus, patients with post-gastric bypass hyperinsulinaemic hypoglycaemia are not candidates for GLP-1 receptor imaging in vivo using radiolabelled exendin. These GLP-1 receptor data support the notion that the islet pathobiology of post-gastric bypass hypoglycaemia is distinctly different from that of benign insulinomas.
Diabetologia 12/2010; 53(12):2641-5. · 6.81 Impact Factor
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Surgical Endoscopy 04/2007; 21(3):367-72. · 4.01 Impact Factor
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Surgical Endoscopy 02/2007; 21(3):367-372. · 4.01 Impact Factor
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ABSTRACT: Video trainers may best offer visually realistic laparoscopic simulation, whereas virtual reality (VR) modules may best provide multidimensional objective measures of performance. This study compares the construct and face validity of three different laparoscopic simulators.
Subjects were voluntarily enrolled at the Learning Center during the 2004 SAGES annual meeting. Each subject completed two repetitions of a single task on each of three simulators, MIST-VR, Endotower, and CELTS; performance scores were automatically generated and recorded. Scores of individuals with various levels of experience were compared to determine construct validity for each simulator. Experience was defined according to four parameters: (a) PGY level, (b) fellowship training, (c) basic laparoscopic cases, and (d) advanced laparoscopic cases. Subjects rated each simulator regarding six face validity (realism of simulation) parameters using a 10-point Likert scale (10 = best rating) and participant scores were compared to previously established expert scores (proficiency goals for training).
Ninety-one attendees completed the study. Construct validity was demonstrated for all three simulators; significant differences in scores were detected according to one parameter for MIST-VR, two parameters for Endotower, and all four parameters for CELTS. Face validity was rated as good to excellent for all three simulators (7.0 +/- 0.3 for MIST-VR, 7.9 +/- 0.3 for Endotower [p < 0.001 vs MIST-VR], and 8.7 +/- 0.1 for CELTS [p = 0.001 vs MIST-VR, p = 0.01 vs Endotower]); 6%, 0%, and 36% of "expert" participants obtained expert scores on MIST-VR, Endotower, and CELTS, respectively.
All three simulators demonstrated significant construct and reasonable face validity. Although virtual reality holds great promise to expand the scope of laparoscopic simulation, current interfaces may limit their utility for assessment. Computer-enhanced video trainers may offer an improved interface while incorporating useful multidimensional metrics. Further work is needed to establish standards for appropriate skills assessment methods and performance levels using simulators.
Surgical Endoscopy 02/2006; 20(1):104-12. · 4.01 Impact Factor
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ABSTRACT: BackgroundVideo trainers may best offer visually realistic laparoscopic simulation, whereas virtual reality (VR) modules may best provide
multidimensional objective measures of performance. This study compares the construct and face validity of three different
laparoscopic simulators.
MethodsSubjects were voluntarily enrolled at the Learning Center during the 2004 SAGES annual meeting. Each subject completed two
repetitions of a single task on each of three simulators, MIST-VR, Endotower, and CELTS; performance scores were automatically
generated and recorded. Scores of individuals with various levels of experience were compared to determine construct validity
for each simulator. Experience was defined according to four parameters: (a) PGY level, (b) fellowship training, (c) basic
laparoscopic cases, and (d) advanced laparoscopic cases. Subjects rated each simulator regarding six face validity (realism
of simulation) parameters using a 10-point Likert scale (10 = best rating) and participant scores were compared to previously
established expert scores (proficiency goals for training).
ResultsNinety-one attendees completed the study. Construct validity was demonstrated for all three simulators; significant differences
in scores were detected according to one parameter for MIST-VR, two parameters for Endotower, and all four parameters for
CELTS. Face validity was rated as good to excellent for all three simulators (7.0 ± 0.3 for MIST-VR, 7.9 ± 0.3 for Endotower
[p < 0.001 vs MIST-VR], and 8.7 ± 0.1 for CELTS [p = 0.001 vs MIST-VR, p = 0.01 vs Endotower]); 6%, 0%, and 36% of “expert” participants obtained expert scores on MIST-VR, Endotower, and CELTS,
respectively.
ConclusionsAll three simulators demonstrated significant construct and reasonable face validity. Although virtual reality holds great
promise to expand the scope of laparoscopic simulation, current interfaces may limit their utility for assessment. Computer-enhanced
video trainers may offer an improved interface while incorporating useful multidimensional metrics. Further work is needed
to establish standards for appropriate skills assessment methods and performance levels using simulators.
Surgical Endoscopy 12/2005; 20(1):104-112. · 4.01 Impact Factor
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M E Patti,
G McMahon,
E C Mun,
A Bitton,
J J Holst,
J Goldsmith,
D W Hanto, M Callery,
R Arky,
V Nose,
S Bonner-Weir,
A B Goldfine
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ABSTRACT: Postprandial hypoglycaemia following gastric bypass for obesity is considered a late manifestation of the dumping syndrome and can usually be managed with dietary modification. We investigated three patients with severe postprandial hypoglycaemia and hyperinsulinaemia unresponsive to diet, octreotide and diazoxide with the aim of elucidating the pathological mechanisms involved.
Glucose, insulin, and C-peptide were measured in the fasting and postprandial state, and insulin secretion was assessed following selective intra-arterial calcium injection. Pancreas histopathology was assessed in all three patients.
All three patients had evidence of severe postprandial hyperinsulinaemia and hypoglycaemia. In one patient, reversal of gastric bypass was ineffective in reversing hypoglycaemia. All three patients ultimately required partial pancreatectomy for control of neuroglycopenia; pancreas pathology of all patients revealed diffuse islet hyperplasia and expansion of beta cell mass.
These findings suggest that gastric bypass-induced weight loss may unmask an underlying beta cell defect or contribute to pathological islet hyperplasia, perhaps via glucagon-like peptide 1-mediated pathways.
Diabetologia 12/2005; 48(11):2236-40. · 6.81 Impact Factor
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ABSTRACT: Activation of epidermal growth factor receptor (EGFR) is associated with cell growth and transformation. Both transforming growth factor-alpha (TGF-alpha) and epidermal growth factor bind to and activate EGFR. We studied the expression of TGF-alpha and two EGFRs (HER-1 and HER-2) in gastrointestinal stromal tumours (GISTs) of the stomach (n = 9) and small intestine (n = 6) using standard immunostaining techniques in paraffin-embedded sections. Most GISTs expressed TGF-alpha, and a few expressed HER-1. All HER-1-positive tumours expressed TGF-alpha. These results suggest that a TGF-alpha/EGFR autocrine loop is present in GIST and that TGF-alpha promotes proliferation of GIST tumour cells through its interaction with HER-1 in at least some GISTs. This is the first description of an autocrine loop in GIST. In contrast, HER-2 is not expressed in any GIST.
Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 09/1999; 435(2):112-5. · 2.49 Impact Factor
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ABSTRACT: The purpose of this prospective study was to compare the accuracies of laparoscopic sonography and laparoscopic videofluoroscopic cholangiography in detecting common bile duct stones and in identifying ductal anomalies during laparoscopic cholecystectomy.
Ninety-five patients who underwent laparoscopic videofluoroscopic cholecystectomy were prospectively studied with laparoscopic sonography and laparoscopic videofluoroscopic cholangiography. The number of successful studies, the time required to complete the study, and complications resulting from the study were recorded. The biliary system was evaluated for complete visualization of the common bile duct, visualization of the cystic duct, ductal anomalies, maximum diameter of the common bile duct, and common bile duct stones and/or debris. Also determined was whether laparoscopic sonographic findings altered operative management.
Laparoscopic sonography was successfully performed in 93 of 95 patients, and laparoscopic videofluoroscopic cholangiography was successfully performed in 90 of 95 patients. The time required to complete laparoscopic sonography ranged from 3 to 18 min (mean +/- SD, 8 +/- 3 min), and that required to complete laparoscopic cholangiography ranged from 5 to 28 min (mean +/- SD, 14 +/- 6 min). Laparoscopic sonography visualized the complete common bile duct in 84 of 93 patients, and laparoscopic cholangiography did so in 86 of 90 patients. Laparoscopic sonography showed the cystic duct in 87 of 93 patients, and laparoscopic cholangiography did so in 80 of 90 patients. Laparoscopic sonography showed no ductal anomalies in any of the 93 patients. Laparoscopic cholangiography showed ductal variants in 13 of 90 patients; however, 11 of the variants were proximal to the sonographic scan plane. Laparoscopic sonography showed common bile duct stones in 12 of 93 patients, and laparoscopic cholangiography did so in five of 90 patients. Laparoscopic sonography altered operative management in two of 93 patients.
Our results show that laparoscopic sonography is as accurate as laparoscopic videofluoroscopic cholangiography in visualizing the common bile duct and cystic duct and in detecting common bile duct stones. However, the data are too limited to determine whether laparoscopic sonography is as accurate as laparoscopic cholangiography in detecting ductal anomalies.
American Journal of Roentgenology 11/1995; 165(4):847-51. · 2.78 Impact Factor
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Archivum Immunologiae et Therapiae Experimentalis 02/1981; 29(6):851-5. · 2.54 Impact Factor
