Methodology and Results of a Joint IFSO-WGO Delphi Survey of 94 Intercontinental, Interdisciplinary Experts in Obesity Management

BACKGROUND

Obesity affects 1.5 billion people worldwide, yet few are treated effectively and considerable variability exists in its management. In 2020, a joint International Federation of Surgery for Obesity and Metabolic Diseases (IFSO) and World Gastroenterology Organization (WGO) advisory committee initiated the drafting of consensus guidelines on obesity management, to be based on detailed literature reviews and the results of an extensive multi-disciplinary survey of intercontinental experts. This paper reports on the latter. The objective of this study is to identify areas of consensus and non-consensus among intercontinental, inter-disciplinary experts in obesity management.

METHODS

Guided by an international consensus-survey expert, a three-round online Delphi survey was conducted in the summer of 2021 of international obesity-management experts spanning the fields of medicine, bariatric endoscopy and surgery, psychology, and nutrition. Issues like epidemiology and risk factors, patient selection for metabolic and bariatric surgery (ASMBS-Clinical-Issues-Committee, Surg Obes Relat Dis : Off J Am Soc Bariatric Surg. 8:e27-32, 1), psychological issues, patient preparation for MBS, bariatric endoscopy, and outcomes and follow-up were addressed.

RESULTS

Ninety-four experts from six continents voted on 180 statements, with consensus reached on 158, including consensus agreement with 96 and disagreement with 24 statements (38 had other response options besides agree/disagree). Among unanimous opinions were the need for all medical societies to work together to address obesity, for regular regional and national obesity surveillance, for multi-disciplinary management, to recognize the increasing impact of childhood and adolescent obesity, to accept some weight regain as normal after MBS, and for life-long follow-up of MBS patients.

CONCLUSIONS

Obesity is a major health issue that requires aggressive surveillance and thoughtful multidisciplinary management.

High definition digital video links for surgical training

We established an interactive digital video link between specialists at Flinders University, South Australia and Kyushu University, Japan, with a third site at the National University of Singapore. The system provided standard definition, non-compressed video at 30 frames per second and required 32 Mbit/s bandwidth per bidirectional connection. The quality of the surgical images was sufficient to allow surgeons at remote sites to develop a good idea of the surgical technique, and there was general agreement that this was a viable tool for remote surgical training. The images and interactions were significantly better than those typical of conventional videoconferencing. The challenge now is to develop structured education sessions utilising additional materials to supplement the surgical sessions, and to develop an appropriate pedagogical framework for this form of learning.

Banding Together: An Investigation of Post-Surgery Support Groups for Laparoscopic Adjustable Gastric Banding Patients

Though advocated as useful for patients, there is little in the literature regarding the use and effectiveness of bariatric support groups. This study investigated characteristics and experiences of bariatric patients who did and did not attend offered groups. Seventy-eight postoperative laparoscopic adjustable gastric banding patients from a private bariatric clinic completed mailed self-report questionnaires. Almost 60% reported having attended the clinic groups, with most wanting to meet other patients and obtain information rather than access psychological assistance. Participants reported generally positive experiences of attending. Nonattendance was often attributed to practical barriers. Satisfaction with support from others was not related to past or predicted future attendance, but higher psychological distress was related to and predictive of greater intention to attend future groups. Likely future attenders also held more positive beliefs about the groups than those who were unlikely to attend. Further research is required into potential positive and negative consequences of attendance, and characteristics of those who are likely to benefit or be harmed by attending. Interventions addressing stereotypes about support groups may help patients make informed decisions about whether to attend a bariatric support group.

Remission of diabetes in patients with long-standing type 2 diabetes following placement of adjustable gastric band: a retrospective case control study

Rates of remission in obese patients with long-standing type 2 diabetes (>2 years), following an adjustable gastric band are unclear. We conducted a retrospective case-control study of patients (n = 89) matched for age and body mass index with non-surgical controls. Cases had a longer duration of diabetes (99 ± 53 and 80 ± 59 months, p < 0.05) and a lower HbA1c than controls (7.9 ± 1.6 vs. 8.5 ± 1.9%, p < 0.05). At follow-up (median 105 weeks) cases had lost 16.8 ± 13.5 kg and controls 1.7 ± 8.9 kg (p < 0.001) and HbA1c decreased by 0.6-0.8% (p < 0.001 for time) with no difference between cases and controls. Diabetes resolution, defined by HbA1c less than 6.5% and taking no medications, occurred in 14 (16%) cases and 2 controls. This is in contrast to published outcomes of resolution of type 2 diabetes after bariatric surgery. We conclude that there is a clear need for randomized studies of the effect of gastric banding in patients with long-standing type 2 diabetes.

Evaluation of the Swedish adjustable gastric band VC (SAGB-VC) in an Australian population: early results

BACKGROUND

The Swedish adjustable gastric band VC (SAGB-VC) has been in use in Australia since 2007. We evaluated its efficacy and safety.

METHODS

We retrospectively analyzed the prospective clinical data of patients who received the implant between November 2007 and June 2009 at 3 Australian bariatric centres.

RESULTS

In all, 1176 patients (mean age 45.9 [standard deviation (SD) 12.3] yr, mean body mass index 43.4 [SD 7.6]) received the SAGB-VC. At a mean follow-up of 11 (SD 3) months, weight reduced by a mean of 18.4 (SD 11.1) kg with an excess weight loss of 37.8% (SD 19.9%). Body mass index decreased (from mean 43.4 [SD 7.7] to mean 36.7 [SD 6.5], p < 0.001). Type 2 diabetes (T2DM) was reported in 167 patients and hypertension in 373. Improvement occurred in 73.5% of patients with T2DM and 31% with hypertension, with patient-reported reduction or cessation of medication. Metabolic syndrome indices improved during follow-up: high-density lipoprotein cholesterol (mean 1.3 [SD 0.3] v. mean 1.4 [SD 0.3] mmol/L, p < 0.001), triglycerides (mean 1.6 [SD 0.8] v. mean 1.3 [SD 0.7] mmol/L, p < 0.001), waist circumference (men 141 [SD 103] to 121 [SD 15] cm, women 117 [SD 14] to 105 [SD 14] cm, both p < 0.001), C-reactive protein (90.5 [SD 75.2] v. 53.3 [SD 61.9] nmol/L, p < 0.001). The complication rate was 4.2%.

CONCLUSION

The SAGB-VC is safe and effective for treating obesity and its comorbidities. The results are reproducible in separate Australian centres and consistent with published literature.

Vagal blocking improves glycemic control and elevated blood pressure in obese subjects with type 2 diabetes mellitus

BACKGROUND

An active device that downregulates abdominal vagal signalling has resulted in significant weight loss in feasibility studies.

OBJECTIVE

To prospectively evaluate the effect of intermittent vagal blocking (VBLOC) on weight loss, glycemic control, and blood pressure (BP) in obese subjects with DM2.

METHODS

Twenty-eight subjects were implanted with a VBLOC device (Maestro Rechargeable System) at 5 centers in an open-label study. Effects on weight loss, HbA1c, fasting blood glucose, and BP were evaluated at 1 week to 12 months.

RESULTS

26 subjects (17 females/9 males, 51 ± 2 years, BMI 37 ± 1 kg/m(2), mean ± SEM) completed 12 months followup. One serious adverse event (pain at implant site) was easily resolved. At 1 week and 12 months, mean excess weight loss percentages (% EWL) were 9 ± 1% and 25 ± 4% (P < 0.0001), and HbA1c declined by 0.3 ± 0.1% and 1.0 ± 0.2% (P = 0.02, baseline 7.8 ± 0.2%). In DM2 subjects with elevated BP (n = 15), mean arterial pressure reduced by 7 ± 3 mmHg and 8 ± 3 mmHg (P = 0.04, baseline 100 ± 2 mmHg) at 1 week and 12 months. All subjects MAP decreased by 3 ± 2 mmHg (baseline 95 ± 2 mmHg) at 12 months.

CONCLUSIONS

VBLOC was safe in obese DM2 subjects and associated with meaningful weight loss, early and sustained improvements in HbA1c, and reductions in BP in hypertensive DM2 subjects. This trial is registered with ClinicalTrials.gov NCT00555958.

Galanin receptor 3--a potential target for acute pancreatitis therapy

BACKGROUND

Galanin participates in the pathogenesis of acute pancreatitis (AP). The galanin receptor (GALR) sub-types involved, however, are unclear. We aimed to determine GALRs messenger RNA (mRNA) expression in mouse pancreas, describe their localization, and ascertain if GALR2 and GALR3 are involved in AP.

METHODS

Galanin receptor expression in murine whole pancreas, acinar, and islet cells was quantified by polymerase chain reaction amplification of reverse-transcribed RNA for mRNA, Western blot analysis for protein and in situ hybridization for GALR localization. Isolated acinar cells were used to determine galanin's effect on amylase secretion. Acute pancreatitis was induced in mice by caerulein injections. Mice, with and without AP, were treated with the highly selective GALR2 antagonist M871, or the specific GALR3 antagonist SNAP-37889. Indices of AP were measured at 12 h.

KEY RESULTS

Murine pancreas expresses mRNA for GALRs. In islets the expression of all GALR are comparable, whereas in acinar cells GALR3 is predominantly expressed. Western blot analysis confirmed that the GALR proteins are expressed by acinar cells. In situ hybridization analysis confirmed that GALR3 mRNA is present in islet and acinar cells, while mRNA for GALR1 and 2 is confined to islets. Galanin did not influence basal and caerulein-stimulated amylase release from acinar cells. M871 treatment reduced some, whereas SNAP-37889 treatment reduced all indices of AP (by 40-80%).

CONCLUSIONS & INFERENCES

Galanin receptor mRNA and protein are expressed in mouse pancreas, with GALR3 mRNA predominating. GALR3 antagonism reduced the severity of AP whereas GALR2 antagonism was less effective. GALR3 is a potential target for treatment of AP.

Galanin receptor antagonist m35 but not m40 or c7 ameliorates cerulein-induced acute pancreatitis in mice

BACKGROUND/AIMS

We compared the galanin antagonists C7, M35, M40 and galantide, for their ability to ameliorate acute pancreatitis (AP).

METHODS

Galanin antagonists were co-administered with 7 hourly cerulein injections used to induce AP. Plasma amylase and lipase activities were measured as indices of AP, and pancreata were harvested at 12 h for histological examination and estimation of myeloperoxidase (MPO) activity.

RESULTS

Treatment with galantide, M35 and C7 ameliorated the AP-induced plasma hyperenzymemia by 40-75%. Administration of M40 did not significantly alter plasma hyperenzymemia. Galantide, M35 and M40 significantly reduced the pancreatic MPO activity by 65-80%, whereas C7 increased MPO activity. Galantide and M35 but not C7 or M40 treatment significantly reduced the AP-induced necrosis score by 30-50% compared to the AP alone group. C7 alone increased plasma lipase activity and the pancreatic necrosis score compared with saline treatment alone, whereas the other antagonists were without effect.

CONCLUSION

Galantide and M35 ameliorated the severity of AP, but M40 and C7 had mixed effects. Complex galanin pathways may be involved in cerulein-induced AP. M35 and galantide are potential therapeutic peptides for the treatment of AP and further evaluation should be considered. and IAP.

Abdominal adiposity and liver fat content 3 and 12 months after gastric banding surgery

Weight loss after laparoscopic adjustable gastric banding surgery (LAGB) is associated with mobilization of adipose tissue from a variety of depots. We sought to evaluate and relate abdominal and hepatic lipid deposition in an obese female population 3 and 12 months after LAGB. We related changes in these depots to markers of insulin sensitivity. Eighteen female obese subjects underwent magnetic resonance imaging and spectroscopy before and 3 and 12 months after LAGB for the quantification of abdominal subcutaneous (ABSAT) and visceral (VAT) adipose tissue areas and liver fat content (LFAT). Fasting blood free fatty acids (FFA) were analyzed. Insulin sensitivity was assessed by the homeostasis model assessment of insulin resistance index (HOMA-R). Mean weight loss 3 and 12 months after LAGB was 9.8 +/- 1.1 kg and 20.0 +/- 2.2 kg, respectively. Postoperatively, VAT area loss exceeded ABSAT area loss in the cohort as a whole and when divided according to preoperative liver fat stores. Three months after LAGB, reductions had occurred in VAT and ABSAT areas (both P < .01) and in FFA (P < .05). Twelve months after LAGB, further significant reductions (P < .01) occurred in VAT and ABSAT areas but not in FFA. No significant reduction occurred in LFAT at either time point in the group as a whole. In those with preoperative hepatic steatosis (LFAT > approximately 5%, n = 7), LFAT fell by 42% (P = .036) 3 months after LAGB, with a total reduction of 50% (P = .027 cf baseline) occurring by 12 months. There was an improvement in HOMA-R at 12 months (1.9 +/- 0.3 cf 2.9 +/- 0.5 at baseline, P = .04) but not 3 months (2.7 +/- 0.4). Preoperatively, LFAT related significantly to VAT area (r = 0.67, P = .003) and HOMA-R (r = 0.497, P = .04) but not ABSAT area. Postoperatively at both 3 and 12 months, LFAT continued to relate to VAT area (r = 0.63, P < .01 at both time points) but not HOMA-R. The changes in LFAT and VAT area were unrelated postoperatively. Abdominal adipose tissue loss was greater from the visceral than subcutaneous depots, suggesting that insulin sensitivity may not be an important determinant of selective lipid depot loss. The lack of a significant change in liver fat in the group as a whole may relate to low preoperative liver fat stores and to high postoperative dietary fat intakes. Preoperative liver fat stores did not influence insulin sensitivity or abdominal lipid changes during weight loss. Liver fat content and VAT area interrelated more closely than either related to ABSAT area, suggesting differing regulatory pathways for fat mobilization from ABSAT and VAT depots but possibly similar pathways for storage and mobilization of fat in the liver and viscerally.

A novel preparation to study rat pancreatic spinal and vagal mechanosensitive afferents in vitro

The management of pancreatic pain is a significant clinical problem so understanding of how sensory signals are generated in pancreatic tissue is fundamental. We aimed to characterize mechanosensitive and chemosensitive properties of pancreatic spinal and vagal afferents in vitro. Spinal and vagal afferent preparations from Sprague-Dawley rats were established incorporating the left splanchnic nerve or vagus nerves respectively. The common bile duct was cannulated for distension of the pancreatic duct with fluid. Nerve discharge evoked by blunt probing, duct distension or electrical stimulation was obtained from teased nerve bundles using standard extra-cellular recording. Discharge from 197 spinal afferent bundles was recorded, of which 57% displayed spontaneous activity. Blunt probing revealed 61 mechanosensitive receptive fields which were associated primarily with arteries/blood vessels (33/61) and the parenchyma (22/61). All mechanosensitive responses were slowly adapting, with 33% continuing to discharge after termination of the stimulus and 60% displaying a response threshold <10 g. Application of chemical mediators (bradykinin, histamine, 5-hydroxytryptamine, cholecystokinin octapeptide) evoked a response from 31/57 units, with 33% excitatory and 23% inhibitory. Spontaneous discharge was recorded from 72% of 135 vagal bundles. Mechanosensitive receptive fields were not identified in the pancreas but were evident in adjacent organs. No spinal or vagal afferent response to duct distension was obtained. In conclusion, pancreatic mechanosensitive spinal afferents are common, in contrast to pancreatic mechanosensitive vagal afferents indicating that pancreatic sensory innervation is predominantly spinal. Chemosensitive spinal afferent nerve endings are present in the pancreas and respond to a variety of inflammatory and physiological mediators.

Associates of change in liver fat content in the morbidly obese after laparoscopic gastric banding surgery

AIM

Hepatic steatosis affects up to 30% of the population. After weight loss, monitoring of the change in hepatic steatosis is not routinely performed. This study aimed to define the closest associates of change in liver fat content in a population of obese females following laparoscopic gastric banding surgery.

METHODS

Before and 3 months after surgery, proton magnetic resonance spectroscopy and magnetic resonance imaging were used to estimate the amount of lipid contained within the liver and abdominal subcutaneous and visceral compartments of 29 obese [mean body mass index (BMI) 39 +/- 5 kg/m(2)], non-diabetic women aged between 20 and 62 years. Liver enzymes, fasting plasma glucose and insulin were also measured as well as body weight, BMI and waist circumference. Insulin sensitivity was estimated using homeostasis model assessment insulin resistance index.

RESULTS

Significant reductions occurred in body weight (p < 0.001), abdominal fat volumes (p < 0.001) and liver fat (p = 0.037) 3 months after surgery. Change in liver fat content more closely associated with change in serum gamma-glutamyl transferase (GGT; r = 0.71, p < 0.001) than with changes in weight (r = 0.10, p = 0.612) and waist circumference (r = 0.15, p = 0.468).

CONCLUSIONS

Our findings suggest that obese non-diabetic female patients who have undergone significant weight loss over 3 months can be better assessed for the regression of excess liver fat content by monitoring changes in serum GGT levels rather than changes in simple anthropometry.

Intra-abdominal vagal blocking (VBLOC therapy): clinical results with a new implantable medical device

BACKGROUND

A new medical device uses high-frequency electrical algorithms to create intermittent vagal blocking (VBLOC therapy). The aim is to assess the effects of vagal blocking on excess weight loss (EWL), safety, dietary intake, and vagal function.

METHODS

An open-label, 3-center study was conducted in obese subjects (body mass index [BMI] 35-50 kg/m(2)). Electrodes were implanted laparoscopically on both vagi near the esophagogastric junction to provide electrical block. Patients were followed for 6 months for body weight, safety, electrocardiogram, dietary intake, satiation, satiety, and plasma pancreatic polypeptide (PP) response to sham feeding. To specifically assess device effects alone, no diet or exercise programs were instituted.

RESULTS

Thirty-one patients (mean BMI, 41.2 +/- 1.4 kg/m(2)) received the device. Mean EWL at 4 and 12 weeks and 6 months after implant was 7.5%, 11.6%, and 14.2%, respectively (all P < .001); 25% of patients lost >25% EWL at 6 months (maximum, 36.8%). There were no deaths or device-related serious adverse events (AEs). Calorie intake decreased by >30% at 4 and 12 weeks and 6 months (all P <or= .01), with earlier satiation (P < .001) and reduced hunger (P = .005). After 12 weeks, plasma PP responses were suppressed (20 +/- 7 vs 42 +/- 19 pg/mL). Average percent EWL in patients with PP response <25 pg/mL was double that with PP response >25 pg/mL (P = .02). Three patients had serious AEs that required brief hospitalization, 1 each for lower respiratory tract, subcutaneous implant site seroma, and Clostridium difficile diarrhea.

CONCLUSIONS

Intermittent, intra-abdominal vagal blocking is associated with significant EWL and a desirable safety profile.

Selective iNOS inhibition enhances spontaneous gallbladder motility in the Australian possum

Gallbladder inflammation is a common and painful disease. Inducible nitric oxide synthase (iNOS) plays a major role in inflammatory diseases, and iNOS inhibitors are being developed as therapeutic agents. Reports are inconsistent regarding iNOS expression in normal gallbladder. The aim of this study was to determine the effect of iNOS inhibition on spontaneous gallbladder motility. mRNA extracted from normal possum gallbladders was analysed by PCR. Gallbladder contractility was evaluated using a highly selective iNOS inhibitor AR-C102222AA (AR-C) in in vitro muscle strips (0.1-10 000 microm) and in vivo (0.1-30 micromol kg(-1)) experiments. Gene expression analysis revealed the presence of iNOS mRNA in normal gallbladder (n = 3). In vitro, AR-C (0.1-1000 micromol L(-1)) produced a concentration-dependent increase in spontaneous gallbladder contractile activity and basal tension (P < 0.05; n = 6). The maximum effect was a 1.8-fold increase in activity and 2.1-fold increase in basal tension. Pretreatment of muscle strips with tetrodotoxin (1 micromol L(-1)) did not block the AR-C-induced response (n = 5). In vivo, AR-C (30 micromol kg(-1), i.v.) increased gallbladder contraction frequency (P < 0.05; n = 8). These data suggest that iNOS is continually expressed in the normal gallbladder, which presumably releases low levels of nitric oxide and in turn may modulate spontaneous gallbladder motility. AR-C may be a beneficial treatment for patients suffering from acute cholecystitis.

Sphincter of Oddi function in the Australian brush-tailed possum is inhibited by intragastric ethanol

The role of sphincter of Oddi (SO) function in alcoholic acute pancreatitis (AP) is unclear. We aimed to compare the effect of i.v. and intragastric (IG) ethanol on SO function (i.e. trans-sphincteric flow; TSF) and investigate possible neural mechanisms. The involvement of gastric mucosal damage was also investigated by pretreatment with pantoprazole. In anaesthetized Australian possums, blood pressure (BP), TSF and blood ethanol concentrations were measured after i.v. or IG ethanol. Possums were subjected to acute vagotomy, atropine, L-nitro arginine methyl ester (L-NAME) or pantoprazole pretreatment prior to IG ethanol. BP was not significantly altered by ethanol. Ethanol decreased TSF in a dose and route-dependent manner. The lowest dose of IG ethanol reduced TSF but this response was not duplicated by i.v. ethanol producing the same blood ethanol concentrations. Acute vagotomy, atropine or L-NAME pretreatment blocked the ethanol-induced decrease in TSF and simultaneously suppressed the blood ethanol concentration. Pantoprazole pretreatment reduced the TSF response and blood ethanol concentrations implicating mechanisms induced by gastric mucosal damage. We conclude that ethanol (and/or its metabolites) reduces TSF via humoral and neural mechanisms involving vagal pathways, muscarinic receptors and nitric oxide. Reduced TSF could contribute to the onset of AP.

Exogenous purines induce differential responses in the proximal and distal regions of the possum sphincter of Oddi

1. The aim of this study was to compare the effect of exogenous ATP and adenosine on spontaneous motility of the proximal and distal regions of the possum sphincter of Oddi (SO). 2. ATP or adenosine (1 microm-1 mm) was applied to distal-SO or proximal-SO muscle rings in organ baths in the absence or presence of tetrodotoxin (TTX) or P1/P2 antagonists. 3. Both ATP and adenosine altered spontaneous activity, predominantly in proximal-SO rings. 4. Exogenous ATP induced a bi-phasic response consisting of a brief TTX-sensitive excitatory component, and a longer-lasting TTX-insensitive inhibitory component. 5. The excitatory ATP response likely involves P2X receptors, whereas the late inhibitory response likely involves P2Y receptors. 6. Exogenous adenosine decreased spontaneous SO activity, via a TTX-insensitive mechanism. 7. Exogenous purines modulate SO motility, acting primarily in the proximal region of the SO, via neural and non-neural mechanisms and multiple purine receptor subtypes.

Effects of cholecystokinin and secretin on pancreatic duct pressure and pancreatic blood flow in Australian brush-tailed possums

AIM: To investigate the effects of cholecystokinin (CCK) and secretin on pancreatic duct pressure (PDP) and pancreatic blood flow (PBF) in Australian brush-tailed possums.

METHODS: CCK and secretin (5 mg/kg) were intravenously injected into 6 brush-tailed possums respectively. Pancreatic duct of the possums were cannulated and PDP was measured by Maclab recording system separately. PBF was measured using laser Doppler flowmetry.

RESULTS: Five minutes after CCK and secretin injection, PDP increased from 16.2 ± 1.8 and 16.8 ± 1.7 mmHg to 18.9 ± 2.1 and 25.6 ± 1.9 mmHg, and maintained high levels (17.6 ± 2.4 mmHg and 21.5 ± 2.5 mmHg) at the 15^th minute (P < 0.002 and P < 0.001); PBF increased from 0.58 ± 0.09 and 0.55 ± 0.04 mL/100 g to 0.75 ± 0.11 and 0.85 ± 0.12 mL/100 g, respectively, at the beginning after CCK and secretin injection. However, CCK and secretin made a continual PDP increase along with PBF decrease till maintaining a low level (0.51 ± 0.09 mL/100 g and 0.39 ± 0.11 mL/100 g, P < 0.001) within 15 minutes, but the influence of secretin was more significant than that of CCK (P < 0.05).

CONCLUSION: PDP can be increased by CCK and secretin injection, resulting in an increase of PBF, which may be the initial factor in the pathogenesis and development of acute biliary pancreatitis.

Change in liver size and fat content after treatment with Optifast very low calorie diet

BACKGROUND

Laparoscopic adjustable gastric banding (LAGB) requires surgical access to the gastroesophageal junction, which may be compromised by the enlarged, fatty liver that is frequently encountered in the obese. Liver size appears reduced and surgical access improved following preoperative weight loss with Optifast Very Low Calorie Diet (VLCD). The aim of this study was to assess the effects of 6 weeks Optifast VLCD on liver volume and fat content.

METHODS

18 morbidly obese subjects underwent magnetic resonance imaging and spectroscopy to measure liver size and fat content before and after intensive treatment with Optifast VLCD for 6 weeks.

RESULTS

All subjects completing 6 weeks Optifast VLCD lost weight. Body weight and BMI (median [interquartile range]) reduced from 119.7 [111.9-131.3] kg and 44 [40-51] kg/m(2) respectively, to 110.6 [98.0124.5] kg and 40 [36-47] kg/m(2), P<0.001. Median excess weight loss (EWL) was 15.1 [9.6-21.1]%. Baseline liver volume and fat content were related (r=0.633, P=0.005). After 6 weeks Optifast VLCD, there was a 14.7% reduction in mean liver volume (P<0.001) and a 43% reduction in mean liver fat (P=0.016). The change in liver volume was predicted by the change in the liver fat (r = 0.610, P=0.012).

CONCLUSION

This study has demonstrated that a 6 week diet with Optifast VLCD results in significant related reductions in liver size and liver fat content. This suggests that the reduction in liver volume is due to loss of fat. The reduction in liver fat and volume likely accounts for the perceived improved operability in patients undergoing LAGB.

Exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of oddi motility via neural mechanisms in the anesthetized Australian possum

We aimed to determine if exogenous adenosine triphosphate or adenosine modulated sphincter of Oddi motility and involved neural mechanisms. Sphincter of Oddi motility was recorded in anesthetized possums by manometry. Adenosine triphosphate or adenosine (1 microM-10 mM) was applied topically to the sphincter before and after pretreatment with tetrodotoxin, hexamethonium, atropine, or Nomega-nitro-L-arginine methyl ester. Sphincter contraction amplitude and frequency were quantified. Adenosine triphosphate induced a concentration-dependent increase in proximal sphincter contraction amplitude and frequency (P < 0.05). This response was reduced by tetrodotoxin and atropine but enhanced by hexamethonium and Nomega-nitro-L-arginine methyl ester. Adenosine concentration dependently increased proximal sphincter contraction amplitude (P < 0.05) only. This response was reduced by tetrodotoxin, atropine, and Nomega-nitro-L-arginine methyl ester, whereas hexamethonium had no effect. We conclude that exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of Oddi motility via neural mechanisms, involving cholinergic motor neurons. Adenosine triphosphate may further modulate sphincter motility via nicotinic and nitrergic pathways.

Pancreatobiliary afferent recordings in the anaesthetised Australian possum

The sensory innervation to the pancreatobiliary system is poorly characterized. Afferent signals from the gastrointestinal tract and biliary tree are transmitted to the central nervous system via the vagus and spinal nerves. We aimed to record afferent discharge in order to characterize the vagal and splanchnic afferent signals from the possum upper gastrointestinal tract, biliary tree and pancreas. In 21 anaesthetised possums nerve fibres were teased from the vagus or splanchnic nerve for multi-unit recording. Mechanical stimuli consisted of balloon distension of the gallbladder and duodenum (2-7 ml) and fluid distension (0-20 mm Hg) of the bile or pancreatic ducts. Approximately 60% of fibres from all nerves displayed spontaneous discharge. Spinal afferent responses to mechanical stimuli were infrequent (n=13). Increased discharge occurred in response to duodenal (12/99 fibres) or gallbladder (7/96 fibres) distension, but not to bile duct (0/73 fibres) or pancreatic duct (0/51 fibres) distension. Vagal afferent responses to distension of the duodenum or stomach (5-30 ml) were more common (n=8). Increased discharge was recorded in response to duodenal (49/134 fibres), or gastric (22/70 fibres) distension. Responses to gallbladder distension were less frequent (6/99 fibres) and as with the spinal afferent no response to bile duct (0/66) or pancreatic duct (0/70) distension were recorded. We conclude that mechanosensitive afferents in the pancreatobiliary system are relatively rare, particularly within the ducts, and/or that they are adapted to monitor stimuli other than luminal distension.

Surgical versus endoscopic treatment of bile duct stones

BACKGROUND

10% to 18% of patients undergoing cholecystectomy for gallstones have common bile duct (CBD) stones. Treatment options for these stones include pre- or post-operative endoscopic retrograde cholangiopancreatography (ERCP) or open or laparoscopic surgery.

OBJECTIVES

To systematically review the management of CBD stones by four approaches: (1) ERCP versus open surgical bile duct clearance. (2) Pre-operative ERCP versus laparoscopic bile duct clearance. (3) Post-operative ERCP versus laparoscopic bile duct clearance. (4) ERCP versus laparoscopic bile duct clearance in patients with previous cholecystectomy.

SEARCH STRATEGY

We systematically searched key relevant electronic databases, bibliographies of relevant papers, and abstracts of relevant subspecialty meetings until November 2005.

SELECTION CRITERIA

The quality of included trials was assessed by adequacy of allocation sequence generation, allocation concealment, blinding, and follow-up.

DATA COLLECTION AND ANALYSIS

Published and unpublished data relevant to 12 predefined outcome measures were used to conduct fixed- and random-effects models meta-analyses, with exploration of heterogeneity and use of sensitivity and subgroup analysis where required.

MAIN RESULTS

Thirteen trials randomised 1351 patients. Eight trials (n = 760) compared ERCP with open surgical clearance, three (n = 425) compared pre-operative ERCP with laparoscopic clearance, and two (n = 166) compared post-operative ERCP with laparoscopic clearance. There were no trials of ERCP versus laparoscopic clearance in patients without an intact gallbladder. Methodology was considered adequate in at least two of three assessable fields in ten trials. A significantly increased number of total procedures (including for complications) per patient was seen in the ERCP arms in all three comparisons with weighted mean differences of 0.62 (95% CI 0.15 to 1.09), 0.96 (95% CI 0.96 to 0.96), and 1.09 (95% CI 0.93 to 1.24), respectively. ERCP was less successful than open surgery in CBD stone clearance (Peto OR 2.89, 95% CI 1.81 to 4.61) with a tendency towards higher mortality (risk difference 1%, 95% CI -1% to 4%). Laparoscopic CBD stone clearance was as efficient as pre- (Peto OR 1.00, CI 0.53 to 1.80) and post-operative ERCP (OR 2.27, 95% CI 0.37 to 13.9) and with no significant difference in morbidity and mortality. Laparoscopic trials universally reported shorter hospital stays in surgical arms. Insufficient data were reported for cost analysis.

AUTHORS' CONCLUSIONS

In the era of open cholecystectomy, open bile duct surgery was superior to ERCP in achieving CBD stone clearance. In the laparoscopic era, data are close to excluding a significant difference between laparoscopic and ERCP clearance of CBD stones. The use of ERCP necessitates increased number of procedures per patient.

The Early Effects of Weight Loss Surgery on Regional Adiposity

BACKGROUND

Weight loss beyond 6 months following laparoscopic adjustable gastric banding (LAGB) is associated with a preferential mobilization of visceral adipose tissue and an improvement in insulin sensitivity in insulin resistant subjects. Because the rate of weight loss is greatest in the first 3 months after LAGB, we investigated the impact of LAGB on changes in regional lipid deposition and insulin sensitivity over this period.

METHODS

10 female obese non-diabetic subjects underwent magnetic resonance (MR) imaging and spectroscopy before and 12 weeks after LAGB (using the Swedish band), for the quantification of abdominal subcutaneous and visceral adipose tissue areas and intrahepatic lipid. Fasting blood free fatty acids were analyzed. Insulin sensitivity was monitored by fasting insulin and homeostasis model assessment (HOMA).

RESULTS

Median weight loss 12 weeks after gastric banding was 9.5 kg [interquartile range (IQR): -16.5 to -6]. There were significant reductions in median abdominal subcutaneous (-20% [IQR: -24 to -13]) and visceral (-15% [IQR: -49 to -8]) adipose tissue depots as well as plasma free fatty acids (-34% [IQR: -79 to -8]). The amount of weight lost was directly proportional to the initial BMI (r=0.778; P=0.008). Visceral fat loss was proportional to initial visceral adiposity (r=0.80, P=0.01). There was no significant improvement in insulin sensitivity.

CONCLUSION

Significant fat loss occurs 3 months after LAGB. The absence of a concurrent improvement in insulin sensitivity may reflect the relatively small reduction in visceral adipose tissue at this stage. Improvement in insulin sensitivity beyond 3 months after LAGB may be due to the continued loss of visceral adipose tissue.

The sphincter of Oddi: understanding its control and function

The most common functional disorders of the biliary tract and pancreas are associated with disordered motility of the sphincter of Oddi (SO). The SO is a neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum. The primary functions of the SO are to regulate the delivery of bile and pancreatic juice into the duodenum, and to prevent the reflux of duodenal contents into the biliary and pancreatic systems. Disordered motility of the SO leads to the common and painful clinical conditions of SO dysfunction and acute pancreatitis. In order to understand normal SO motility, studies have been performed addressing SO function, control of spontaneous SO activity, responses to bioactive agents, SO innervation, and reflexes with other gastrointestinal organs. These studies have led to the current understanding of how the SO functions and may permit the development of targeted therapy for SO dysfunction and acute pancreatitis. This review summarizes the current knowledge regarding the control and regulation of SO motility, highlighting laboratory based and clinical research performed over the last 5 years.

Electrical activation of common bile duct nerves modulates sphincter of Oddi motility in the Australian possum

BACKGROUND

Sphincter of Oddi (SO) motility is regulated by extrinsic and intrinsic nerves. The existence of neural circuits between the SO and the proximal extrahepatic biliary tree has been reported, but they are poorly understood. Using electrical field stimulation (EFS), we determined if a neural circuit exists between the common bile duct (CBD) and the SO in anaesthetized Australian brush-tailed possums.

METHODS

The gallbladder, cystic duct or CBD were subjected to EFS with a stimulating electrode. Spontaneous SO phasic waves were measured by manometry.

RESULTS

EFS at sites on the distal CBD (12-20 mm proximal to the SO), but less commonly at more proximal CBD, evoked a variety of responses consisting of an excitatory and/or inhibitory phase. Bi-phasic responses consisting of an excitation followed by inhibition were the most common. Tri-phasic responses were also observed as well as excitation or inhibition only. These evoked responses were blocked by topical application of local anaesthetic to the distal CBD or transection of the CBD. EFS at sites on the gallbladder body, neck or cystic duct did not consistently evoke an SO response. Pretreatment with atropine or guanethidine reduced the magnitude of the evoked response by about 50% (p<0.05), pretreatment with hexamethonium had no consistent effect and pretreatment with a nitric oxide synthase inhibitor increased the response.

DISCUSSION

A neural circuit(s) between the SO and the distal CBD modulates SO motility. Damage to this area of the CBD during bile duct exploration surgery could adversely affect SO motility.

Scorpion venom stimulates biliary/duodenal motility and pancreatic exocrine secretion

Scorpion envenomation causes severe upper abdominal pain associated with nausea and vomiting. Although scorpion venom (SV) stimulates pancreatic and gastric secretion in animal models, its effects on duodenal and biliary motility have not been reported. The aim of this study was to determine the effects of SV on sphincter of Oddi (SO), duodenal and gall bladder motility and pancreatic amylase output. Anaesthetized Australian possums (n = 21) were infused with SV via intravenous or closed intra-arterial routes. Blood pressure, SO, duodenal and gall bladder motility were continuously monitored for 4 h. Trans-sphincteric flow (TSF), an indicator of bile duct resistance, was measured concurrently. The amylase output in pancreatic juice was also measured. SV infusion resulted in profound transient increase in blood pressure, SO motility and a significant decrease in TSF. No significant differences were noted in SO basal pressure changes. A transient increase in gall bladder tone, duodenal contraction amplitude and frequency, and amylase output were noted. Following the peak in blood pressure, amylase output, SO, gall bladder and duodenal motility were depressed. SV induces a rapid but transient increase in biliary and duodenal motility that is associated with stimulation of pancreatic amylase output. These changes may contribute to gastrointestinal symptoms associated with early phases of envenomation.

Highly selective iNOS inhibition and sphincter of Oddi motility in the Australian possum

AIM

Inducible nitric oxide synthase (iNOS) plays a major role in acute pancreatitis. Selective inhibitors of iNOS are being developed as therapeutic agents. Sphincter of Oddi (SO) dysfunction may cause pancreatitis and nitric oxide is necessary for SO relaxation. A new highly selective iNOS inhibitor, AR-C102222AA (AR-C), is evaluated together with the established iNOS inhibitor, L-N(6)-(1-iminoethyl)lysine (L-NIL), and the selective neuronal nitric oxide synthase (nNOS) blocker S-methyl-l-thiocitrulline (SMTC).

METHODS

In anaesthetized Australian Brush-tailed possums, the effect of topical, i.v. or i.a. administration of these drugs was evaluated on spontaneous SO motility, blood pressure (BP) and pancreatic vascular perfusion. SO motility was recorded by manometry and pancreatic vascular perfusion by laser Doppler fluxmetry. Also, the effect of SMTC and AR-C on electrical field stimulation (EFS)-induced non-cholinergic non-adrenergic (NANC) SO relaxation in vitro was evaluated.

RESULTS

Infusion of AR-C (0.1-30 micromol kg(-1)) increased SO contraction frequency (P = 0.026) only at the two highest doses. L-NIL infusion (0.15 to 14.7 micromol kg(-1)) also increased SO contraction frequency at 8.8 micromol kg(-1) (P < 0.05) and reduced SO contraction amplitude at the two highest doses (P < 0.05). SMTC injections (0.5 nmol-2.4 micromol) produced a dose-dependent increase in SO contraction frequency (P = 0.009), but no effect was seen on the other parameters. In vitro SMTC (40-400 microm) inhibited EFS-induced NANC relaxation in a dose-dependent manner (P < 0.0005). In contrast AR-C (10-500 microm) had no effect on EFS-induced NANC relaxation (P > 0.05).

CONCLUSIONS

At low doses, AR-C does not effect SO motility or EFS-induced NO mediated relaxation. However, high doses of AR-C and L-NIL in vivo influenced SO motility by inhibiting nNOS activity and these effects need be considered in relation to therapeutic doses of this agent.

Endogenous endothelin increases gallbladder tone and leads to acute cholecystitis in the Australian possum

Endothelins are bioactive peptides produced by gallbladder epithelial cells. We aimed to determine the role of endothelins in acute cholecystitis. Escherichia coli lipopolysaccharide vs saline (sham) was instilled into the gallbladder lumen of Australian possums. Some animals received the non-selective endothelin antagonist, tezosentan. At 4 or 24 h, plasma and gallbladder endothelins and white blood cell count (WBCC) were determined. Acute cholecystitis was assessed using a histopathology score. In other animals gallbladder tone was determined. At 4h, a dose-dependent 60-fold increase in gallbladder endothelin level occurred (P = 0.001) but other parameters remained comparable with sham animals. Epithelial cells were endothelin-immunoreactive. At 24 h, the WBCC rose (P < 0.007), and severe cholecystitis developed. Gallbladder but not plasma endothelin levels remained elevated. Tezosentan pre-treatment resulted in a histologically normal gallbladder, but the WBCC and gallbladder endothelin levels were elevated. Lipopolysaccharide or saline instillation also caused a time-dependent increase in gallbladder tone over 4 h (P < 0.001), but not in control animals. This increase was reduced by tezosentan treatment. Gallbladder endothelin production is an early event in acute cholecystitis, increases gallbladder tone and plays a crucial role in the inflammatory process.

Endothelin-1 stimulates sphincter of Oddi motility and decreases trans-sphincteric flow: a possible mechanism contributes to cholestasis in disease states

Endothelin-1 (ET-1) is a potent stimulator of gallbladder contractility. Its role in modulation of sphincter of Oddi (SO) motility and trans-sphincteric flow (TSF) has not been evaluated. To characterize the effects of ET-1 on SO motility and TSF, 10 anaesthetized Australian possums (in vivo, n = 6) were given graded doses of ET-1 (5-200 pmol kg-1) via closed intra-arterial injection. Blood pressure, TSF and SO motility (basal pressure, phasic amplitude, contraction frequency) were analysed. For in vitro studies, eight SO rings were subjected to 10-12-10-7 mol L-1 cumulative concentrations of ET-1 in organ bath and SO motility was measured. Data are expressed as mean +/- SEM. Statistical analysis used anova. ET-1 induced a dose-related increase in blood pressure with a maximal increase of 37.5 +/- 2.5 mmHg at 200 pmol kg-1, (P < 0.001). ET-1 also increases SO basal pressure (P < 0.001) and contraction frequency (P < 0.0001). However, the contraction amplitude was not significantly affected. ET-1 decreased TSF in a dose-related manner (P < 0.001) with cessation of TSF at the highest dose (P < 0.001). In vitro studies showed a significant increase in mean SO motility index, and frequency of contractions at higher ET-1 concentrations (10-9-10-7 mol L-1). ET-1 is a potent stimulator of SO motility resulting in a reduction in TSF.

Characterization of the intrinsic and extrinsic innervation of the gall bladder epithelium in the Australian Brush-tailed possum (Trichosurus vulpecula)

Intrinsic neurones of the gall bladder modulate its function. Nitric oxide synthase (NOS) and vasoactive intestinal polypeptide (VIP) are present in gall bladder neurones and nitric oxide and VIP modulate its epithelial functions. As an extensive extrinsic innervation of the gall bladder is also present, the source of the epithelial innervation is unclear. In this study the source of the gall bladder epithelial innervation is defined. Immunoreactivity for VIP, NOS, substance P (SP), calcitonin gene related peptide (CGRP) and tyrosine hydroxylase (TH) in organotypic cultured and freshly fixed gall bladder were compared. Retrograde tracing in vitro from the epithelium was used to identify putative intrinsic secretomotor neurones, which were then characterized by immunohistochemistry. Abundant spinal afferent and sympathetic innervation of the gall bladder epithelium was demonstrated by CGRP/SP and TH immunohistochemistry, respectively. The intrinsic secretomotor innervation of the epithelium is derived exclusively from neurones of the subepithelial plexus. A majority of these neurones were immunoreactive for NOS. Some of the NOS-immunoreactive neurones of the subepithelial plexus also contained VIP and/or SP. Gall bladder subepithelial plexus neurones, containing NOS and/or VIP/SP, innervate the epithelium, as do extrinsic neurones.

A2A and A3 receptors mediate the adenosine-induced relaxation in spontaneously active possum duodenum in vitro

1. The aim of this study was to define the P1 purinergic receptors that regulate spontaneous or adenosine-induced duodenal motor activity. 2. Spontaneous contractile activity was recorded isometrically from possum longitudinal duodenal muscle strips. Adenosine (0.5 micro M-1 mM) was administered noncumulatively and repeated after pretreatment with a P1 antagonist or tetrodotoxin (TTX, 1 micro M), (n=4-7). Antagonists used were: A(1), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 10 nM); A(2A), 8-(3-chlorostyryl)caffeine (CSC, 10 micro M); A(2B), 3-isobutyl-8-pyrrolidinoxanthine (IPDX, 10 micro M); A(3), 9-chloro-2-(2-furanyl)-5-[(phenylacetyl) amino][1,2,4]-triazolo(1,5-c)quinazoline (MRS1220, 10 micro M). Changes in activity are expressed as percentage of baseline. Statistical analysis utilised nonparametric tests. 3. Adenosine (n=34) induced a long-lasting, concentration-dependent decrease in activity by 55.6+/-3.2% area under curve (AUC), 47.3+/-4.0% contraction amplitude, 31.6+/-3.6% basal tension and 10.4+/-1.7% contraction frequency (all P<0.001). The adenosine-induced decrease in contraction amplitude was blocked by CSC (P<0.01) or inhibited by MRS1220 (P<0.03) pretreatment, but not modified by TTX, DPCPX or IPDX pretreatment. 4. Adenosine antagonists modified spontaneous contractile activity. Pretreatment with DPCPX or CSC increased basal tension, whereas IPDX or MRS1220 pretreatment decreased contractile activity. 5. In conclusion, exogenous adenosine reduced duodenal longitudinal motor activity via A(2A) and A(3) receptors. Our findings suggest that endogenous purines may modulate spontaneous duodenal motor activity.

Scintigraphy versus manometry in patients with suspected biliary sphincter of Oddi dysfunction

INTRODUCTION

Sphincter of Oddi (SO) manometry is at present the "gold standard" investigation for patients with suspected biliary SO dysfunction. Non-invasive scintigraphy in cholecystectomised patients using a complex scoring system or the transit time from the hepatic hilum to the duodenum (HDTT) have been promoted as sensitive and specific alternatives.

AIM

To evaluate the scintigraphic scoring system and HDTT in patients with suspected biliary SO dysfunction undergoing SO manometry.

METHODS

Cholecystectomised patients undergoing SO manometry for persistent biliary-type pain, as defined by the Rome II criteria, for which all other causes had been excluded, were prospectively studied. Scintigraphy with cholecystokinin octapeptide infusion was performed within a month prior to manometry. Scoring of the scans and measurement of HDTT was performed by independent blinded observers. Manometry of the biliary sphincter was performed per-endoscopically and defined as abnormal if basal pressure was > or = 40 mm Hg.

RESULTS

Thirty two patients were enrolled (30 females, mean age 45.1 years). Three patients were excluded from analysis because manometry from the bile duct was not technically possible. Eight patients had abnormal manometry. Scintigraphic scoring had a sensitivity of 25-38%, a specificity of 86-89%, positive predictive value (PPV) of 40-60%, and a negative predictive value (NPV) of 75-79%. The coefficient of variation for interobserver variation in scores was 0.72. HDTT sensitivity was 13%, specificity 95%, PPV 50%, and NPV 74%.

CONCLUSIONS

Our findings indicate that scintigraphy using these methods of analysis correlates poorly with manometry in post cholecystectomy patients with suspected biliary SO dysfunction.

The sphincter of Oddi and acute pancreatitis--revisited

BACKGROUND

One of the rare causes of recurrent acute pancreatitis is sphincter of Oddi dysfunction. This condition is objectively diagnosed by manometry of the sphincter of Oddi. An abnormally elevated sphincter of Oddi basal pressure has been shown to predict patients who have a successful outcome after transduodenal sphincteroplasty and pancreatic duct septoplasty.

METHODS

Forty-nine patients presenting with recurrent pancreatitis and who had manometric stenosis of the sphincter of Oddi were treated by transduodenal division of the sphincter of Oddi. Clinical follow-up was conducted over a minimum of 2 years.

RESULTS

In all, 43 patients were either cured or improved. None of these patients had any further episodes of pancreatitis. Three of these patients developed recurrent symptoms and were noted to have restenosis of the sphincter of Oddi. They were treated by insertion of an endoscopic stent into the pancreatic duct.

CONCLUSION

The results from this series of patients re-affirm the efficacy of transduodenal sphincteroplasty and septoplasty for treatment of sphincter of Oddi stenosis in patients presenting with recurrent acute pancreatitis.

Effects of acute pancreatic duct obstruction on pancreatic perfusion: implication of acute pancreatic duct decompression

BACKGROUND

Acute pancreatitis can result in pancreatic ischaemia and necrosis. Pancreatic duct (PD) obstruction may be the first step causing ischaemia in acute pancreatitis. Nitric oxide donors can attenuate acute pancreatitis through improvement in compromised pancreatic perfusion (PP). In this study, we determined if (1) PD obstruction altered PP and (2) PD decompression or L-arginine administration reversed this change.

METHODS

Fifteen Australian possums were randomly assigned to two groups: Animals in group A (n = 6) were subjected to 30 min of PD obstruction and 60 min of PD decompression. Animals in group B (n = 9) were subjected to 120 min PD ligation and 60 min PD decompression. A subset group B (n = 6) were subjected to intravenous L-arginine (100 microg/kg) at the end of 120 min of ligation and at the end of PD decompression. The PP (Laser Doppler fluxmetry), PD pressure and blood pressure were continuously monitored.

RESULTS

PD pressure increased from 2.9 +/- 2.5 to 18.1 +/- 4.9 mmHg following PD ligation. PP was reduced to 67.1% +/- 4.5% (P<0.01) and 46.2% +/- 7.5% (P<0.001) of baseline following 30 and 120 min of PD ligation, respectively. Following 60 min of PD decompression, PP was restored to 89.1% +/- 13.4% (P<0.02) of the baseline in the 30-min group. However, following 120 min PD ligation, PP remained depressed. L-arginine administration after 120 min of PD ligation transiently increased PP from 46.2% +/- 7.5% to 81.1% +/- 8.6% (P<0.03) of baseline. This effect was reproduced if L-arginine was administered at the end of decompression (P<0.05).

CONCLUSION

In patients with acute pancreatitis due to obstructive causes, early decompression of the PD may prevent early pancreatic ischaemia.

Relative effects of dihydropyridine L-type calcium channel antagonism on biliary, duodenal, and vascular tissues: an in vivo and in vitro analysis in Australian brush-tailed possum

Nifedipine is used to treat sphincter of Oddi dysfunction. Its effects on the biliary system and duodenum in relation to its known vascular actions are unclear. Our aims were to determine the relative tissue sensitivities to dihydropyridine L-type calcium channel antagonism in the sphincter of Oddi, gallbladder, duodenum, and vasculature. For in vivo studies, 23 possums received nifedipine at three different doses with blood pressure and sphincter of Oddi manometry recordings. For in vitro studies, tissues from 28 possums were pretreated with nicardipine (10(-8)-10(-5) M) and cumulative concentrations of agonist were administered (carbachol, norepinephrine at 10(-9)-10(-5) M). In in vivo studies, blood pressure fell significantly at a lower dose than sphincter of Oddi motility. In in vitro studies, the sphincter of Oddi was more sensitive than arterial tissue, with the duodenum especially sensitive. In conclusion, in the possum we found that L-type channel antagonism in vivo was more potent to the vasculature than the sphincter of Oddi but this was not confirmed in vitro.

Induction of duodenal motility activates the sphincter of Oddi (SO)-duodenal reflex in the Australian possum in vitro

1 The aim of this study was to determine if stimulation of duodenal motility by duodenal fluid distension or by administration of carbachol, activates the sphincter of Oddi-duodenal reflex, in an in vitro preparation from the Australian possum. 2 Duodenal distension was achieved by infusion of Krebs solution (0-8 cm H2O). In separate experiments, the sphincter of Oddi (SO) was partitioned from the duodenum and carbachol (10(-7) - 5 x 10(-6) M) added to the duodenal compartment. 3 Fluid distension increased duodenal motility to 120-600% of control activity. These treatments induced increased SO motility (to 120-390% of control) in six preparations, reduced activity (to 60% of control) in one and no response in another. 4 Addition of carbachol to the duodenal compartment resulted in increased duodenal motility. SO motility was increased in seven preparations, reduced in another two and no response were evoked in two others. All SO responses were blocked by tetrodotoxin pretreatment. 5 These data suggest that the SO receives inputs from duodenal mechano and/or stretch receptors resulting in excitatory or inhibitory responses, with the excitatory response dominating. These findings support the role for the SO-duodenal reflex in preventing duodenobiliary/pancreatic reflux during periods of elevated duodenal activity.

Inhibitory motor innervation of the gall bladder musculature by intrinsic neurones containing nitric oxide in the Australian brush-tailed possum (Trichosurus vulpecula)

BACKGROUND

Gall bladder functions are modulated by neurones intrinsic to the organ. Data are available on the neurochemical composition of intrinsic and extrinsic nerves innervating the gall bladder but are lacking on specific functional classes of gall bladder neurones.

AIMS

To characterise the intrinsic motor neurones of the gall bladder and identify their roles using pharmacological techniques.

METHODS

Retrograde tracing from the possum gall bladder muscle in vitro allowed identification of intrinsic motor neurones. Subsequently, their content of choline acetyltransferase and nitric oxide synthase, markers of acetylcholine and nitric oxide containing neurones, was established using immunohistochemical techniques. Organ bath pharmacology was used to evaluate neurotransmission by acetylcholine and nitric oxide in gall bladder muscle strips.

RESULTS

Innervation of the gall bladder musculature by neurones of both the muscular and serosal plexuses was demonstrated. A large proportion (62%) of these motor neurones were immunoreactive for nitric oxide synthase. All gall bladder neurones showed immunoreactivity for choline acetyltransferase. Organ bath pharmacology confirmed the neuroanatomical data, showing acetylcholine and nitric oxide mediating neurotransmission to the gall bladder musculature.

CONCLUSIONS

Neurones containing acetylcholine and nitric oxide, located within the muscular and serosal plexuses, provide excitatory and inhibitory motor innervation of the gall bladder, respectively. The large inhibitory innervation suggests active relaxation of the gall bladder during filling, mediated by intrinsic nerves.