Gastric emptying rate measurement after vertical banded gastroplasty

Metabolic networks of the human gut microbiota

The human gut microbiota controls factors that relate to human metabolism with a reach far greater than originally expected. Microbial communities and human (or animal) hosts entertain reciprocal exchanges between various inputs that are largely controlled by the host via its genetic make-up, nutrition and lifestyle. The composition of these microbial communities is fundamental to supply metabolic capabilities beyond those encoded in the host genome, and contributes to hormone and cellular signalling that support the dynamic adaptation to changes in food availability, environment and organismal development. Poor functional exchange between the microbial communities and their human host is associated with dysbiosis, metabolic dysfunction and disease. This review examines the biology of the dynamic relationship between the reciprocal metabolic state of the microbiota-host entity in balance with its environment (i.e. in healthy states), the enzymatic and metabolic changes associated with its imbalance in three well-studied diseases states such as obesity, diabetes and atherosclerosis, and the effects of bariatric surgery and exercise.

Effect of vertical sleeve gastrectomy on food selection and satiation in rats

Vertical sleeve gastrectomy (VSG) is a restrictive procedure that reduces food intake to produce weight loss. Here we assess volume and nutrient effects on the ingestive behavior of VSG and sham surgery animals. Rats given access to Ensure or pelleted chow were used to determine if liquid foods would adversely affect weight loss after surgery. Volume effects were studied by altering the caloric density of Ensure, and dietary preferences for fat and carbohydrate (sucrose) were assessed using a two-bottle test. c-Fos was used to measure neuronal activation in the nucleus of the solitary tract and area postrema in response to intragastric infusions of water, sucrose, or Intralipid. The degree of colocalization with catecholaminergic neurons was also assessed. VSG rats did not show the expected preference for a liquid diet over chow and lacked dietary preferences for fat seen in shams. Preferences for carbohydrate/sucrose solutions were unaffected by surgery. Meal size was reduced by VSG; however, VSG rats were able to alter their volume of intake to compensate for changes in caloric density, and intragastric infusions of water produced similar levels of neuronal activation among VSG, sham, and pair-fed rats. In comparison, nutrient-induced c-Fos activation was substantially increased by VSG. Colocalization between c-Fos and catecholaminergic-expressing neurons was similar among rats treated with water, sucrose, or Intralipid. VSG alters nutrient sensing in a manner that lowers the threshold for satiety and reduces fat preference to induce and maintain weight loss.

All bariatric surgeries are not created equal: insights from mechanistic comparisons

Despite considerable scientific progress on the biological systems that regulate energy balance, we have made precious little headway in providing new treatments to curb the obesity epidemic. Diet and exercise are the most popular treatment options for obesity, but rarely are they sufficient to produce long-term weight loss. Bariatric surgery, on the other hand, results in dramatic, sustained weight loss and for this reason has gained increasing popularity as a treatment modality for obesity. At least some surgical approaches also reduce obesity-related comorbidities including type 2 diabetes and hyperlipidemia. This success puts a premium on understanding how these surgeries exert their effects. This review focuses on the growing human and animal model literature addressing the underlying mechanisms. We compare three common procedures: Roux-en-Y Gastric Bypass (RYGB), vertical sleeve gastrectomy (VSG), and adjustable gastric banding (AGB). Although many would group together VSG and AGB as restrictive procedures of the stomach, VSG is more like RYGB than AGB in its effects on a host of endpoints including intake, food choice, glucose regulation, lipids and gut hormone secretion. Our strong belief is that to advance our understanding of these procedures, it is necessary to group bariatric procedures not on the basis of surgical similarity but rather on how they affect key physiological variables. This will allow for greater mechanistic insight into how bariatric surgery works, making it possible to help patients better choose the best possible procedure and to develop new therapeutic strategies that can help a larger portion of the obese population.

A comparative study of gastric banding and sleeve gastrectomy in an obese diabetic rat model

BACKGROUND

Laparoscopic sleeve gastrectomy (SG) is now a typical restrictive bariatric procedure. The aim of this study was to evaluate the efficacy of SG in comparison with gastric banding (GB) in an obese diabetic rat model.

METHODS

Forty-five male Zucker diabetic fatty rats were divided into three groups: sham-operated (SO) control, GB, and SG. The rats were followed for 6 weeks after surgery, and their body weight change, cumulative food intake, metabolic parameters, plasma levels of ghrelin, glucagon-like peptide-1 and adiponectin, oral glucose tolerance test (OGTT), insulin tolerance test (ITT), and gastric emptying rate were measured.

RESULTS

The GB and SG groups showed significant decreases in weight, cumulative intake, and metabolic parameters and significant improvement of OGTT and ITT results compared with the SO group. There were no significant differences in weight and cumulative food intake between the groups. However, the SG group showed significantly higher gastric emptying rate and plasma level of adiponectin and lower plasma levels of free fatty acid, total cholesterol, and ghrelin compared with the GB group. Furthermore, the SG group showed improvement of OGTT and ITT results in comparison with the GB group.

CONCLUSIONS

In obese diabetic rats, SG may improve glucose and lipid metabolism compared with GB, although there was no significant difference in the effect on body weight loss between the two procedures. The hormonal and digestive changes induced by SG may have relevance to the effects on metabolism.

Transoral gastroplasty for morbid obesity: a multicenter trial with a 1-year outcome

BACKGROUND

Bariatric surgery is associated with specific complications and mortality. Transoral gastroplasty (TOGA) is a transoral restrictive bariatric procedure that might offer the benefits of surgery with a reduced complication rate.

OBJECTIVE

To evaluate the safety and efficacy of TOGA at 12-month follow-up.

DESIGN

Prospective, multicenter, single-arm trial.

SETTING

Two tertiary-care referral medical centers.

PATIENTS

This study involved 67 patients (average age 41.0 years, 47 women, baseline body mass index [BMI] 41.5 kg/m(2); 20 patients with BMI <40).

INTERVENTION

The TOGA procedures were performed by using 2 stapling devices that were used to create a small, restrictive pouch along the lesser gastric curvature. The pouch is designed to give the patient a sustained feeling of satiety after small meals.

MAIN OUTCOME MEASUREMENTS

Excess weight loss, excess BMI loss, safety, and improvements in quality of life, obesity-related comorbidities, and medication use.

RESULTS

Fifty-three patients were available at the 12-month follow-up. Excess BMI loss was 33.9%, 42.6%, and 44.8% at 3, 6, and 12 months, respectively. At 12 months, excess BMI loss was 52.2% for patients with a baseline BMI of <40.0 and 41.3% for patients with a baseline BMI of ≥ 40.0 (P < .05). At 12 months, hemoglobin A(1c) levels decreased from 7.0% at baseline to 5.7% (P = .01); triglyceride levels decreased from 142.9 mg/dL to 98 mg/dL (P < .0001); high-density lipoprotein levels increased from 47.0 mg/dL to 57.5 mg/dL (P < .0001). Two complications occurred: a case of respiratory insufficiency and an asymptomatic pneumoperitoneum treated conservatively.

LIMITATIONS

Small number of patients. Short-term follow-up. Twenty-one percent of patients were not available for the 12-month follow-up.

CONCLUSION

The TOGA procedure allowed a substantial weight loss 1 year after the operation without severe complications. A long-term evaluation is needed before definitive conclusions can be drawn.

Sleeve gastrectomy-a "food limiting" operation

BACKGROUND

Sleeve gastrectomy (SG), which, thus far, is showing good resolution of comorbidities and good weight loss, shows increasing popularity among bariatric surgeons. The aim of this study was to evaluate clinical outcome and the gastric emptying of solid foods, 24 months after SG.

METHODS

Fourteen morbidly obese patients, four males and ten females, median age 41 years (range 29-65), median body mass index (BMI) 49.46 kg/m(2) (range 41.14-55.63), who underwent SG for weight loss, were studied prospectively. Nine patients underwent gastric emptying studies, using radioisotopic technique before, 6 months and 24 months after the operation. The remaining five patients underwent gastric emptying studies, 6 months and 24 months after the operation.

RESULTS

A significant reduction in patients' weight and BMI was evident at 6, 12 and 24 months postoperatively. In the nine patients who underwent gastric emptying studies pre-, 6 and 24 months postoperatively, the T-lag phase duration significantly decreased, following the SG, from 17.30 (range 15.50-20.90) min, to 12.50 (range 9.20-18.00) min at 6 months and 12.16 (range 10.90-20.00) min at 24 months postoperatively (P < 0.05). The gastric emptying half time (T1/2) accelerated significantly postoperatively from 86.50 (range 77.50-104.60) min, to 62.50 (range 46.30-80.00) min at 6 months and 60.80 (range 54.80-100.00) min at 24 months after SG (P < 0.05). The percentage of gastric emptying (%GE) increased significantly postoperatively, from 52 (range 43-58) % to 72 (range 57-97) % at 6 months and 74 (range 45-82) % at 24 months, following SG (P < 0.05). No differences in gastric emptying were observed, when values at 24 months were compared to those at 6 months postoperatively. When the whole group of 14 patients was studied, there were also no significant changes in T-lag, T1/2 and %GE between 6 and 24 months postoperatively.

CONCLUSIONS

Our study indicates the constant effect of SG in the acceleration of gastric emptying of solids, which occurs faster, not only in short but also in long-term postoperatively. Such effects on gastric motility, in combination with the reported alterations in gut hormones, may explain how this 'food limiting' operation results in weight loss.

Numerical analysis of pouch filling and emptying after laparoscopic gastric banding surgery

BACKGROUND

Previous studies have indicated that pouch volume and stoma size are two important factors related to weight loss after laparoscopic gastric banding in morbid obese patients. We hypothesized that there was association among the wall stress, pouch volume, and stoma size in a model for the filling and emptying phases of the pouch.

METHODS

A numerical pouch model with variable pouch volume and stoma size was generated. Uniaxial tensile testing was performed on fundus strips from fresh pig stomach and the mass flow of filling and emptying of the pouch was simulated numerically.

RESULTS

There was an overall qualitative agreement on the volume change between the simulated results and the clinical recording. Increasing the pouch volume size from 22 to 105 ml caused a decrease of the maximum circumferential stress from 14.14 to 11.80 kPa and the maximum longitudinal stress from 9.87 to 6.70 kPa in the pouch wall at the same degree of filling. Decreasing the stoma diameter from 27 to 10 mm caused an increase of the maximum circumferential stress from 11.46 to 12.78 kPa and a decrease of the maximum longitudinal stress from 10.34 to 8.69 kPa.

CONCLUSION

Both the pouch volume and stoma size are important determinants of mechanical wall stress, wall strain, and pouch emptying and hence may affect satiety and weight loss. This information may be important in understanding the mechanical behavior of pouches and for the development of more advanced numerical models in the clinical management of the surgery.

Sleeve gastrectomy: a restrictive procedure?

BACKGROUND

Diet and surgically-induced weight loss have been shown to lead to alterations in motor and sensory function of the stomach. We investigated the clinical outcome and gastric emptying of solid foods in morbidly obese (MO) patients following sleeve gastrectomy (SG).

METHODS

We studied 23 MO patients [(7 males, 16 females), mean age 38.9 +/- 11.0 years (range 20-64 years), mean weight 135.1 +/- 19.0 kg (range 97-167 kg), mean BMI 47.2 +/- 4.8 kg/m(2) (range 39.6-56.0 kg/m(2))] who each underwent a sleeve gastrectomy (SG) for weight reduction. At the monthly follow-up visits, variations in weight and BMI changes, postoperative meal size and frequency, and presence of gastrointestinal symptoms were recorded. 11 patients underwent scintigraphic measurement of the gastric emptying of a solid meal pre- and 6 months postoperatively.

RESULTS

A significant reduction in patients' weight was evidenced at 6 and 12 months postoperatively [98.6 +/- 11.8 kg and 87.0 +/- 10.7 kg respectively (P=0.001)]. BMI decreased to 35.2 +/- 4.3 kg/m(2) at 6 months and to 31.1 +/- 4.5 kg/m(2) at 12 months, respectively (P=0.001). Although meal size was drastically reduced, meal frequency increased postoperatively in 12 patients (52.2%). Only 5 patients (21.8 %) reported occasional vomiting after meals following SG. The gastric emptying half-time (T1/2) accelerated (47.6 +/- 23.2 vs 94.3 +/- 15.4, P<0.01) and the T-lag phase duration decreased (9.5 +/- 2 min vs 19.2 +/- 2 min, P<0.05) post-operatively. The percentage of the meal emptied from the stomach 90 min after consumption increased significantly after SG (75.4 +/- 14.9% vs 49.2 +/- 8.7%, P<0.01).

CONCLUSIONS

This study indicates that following SG, the stomach empties its contents rapidly into the small intestine and symptoms of vomiting after eating (characteristic of restrictive procedures) are either absent or very mild. Therefore, the term 'restrictive' is possibly ill-advised for this new bariatric operation. It remains for other mechanisms of energy intake reduction, such as intestinal distension and satiety signals through gut hormones to be investigated, to comprehensively explain precisely how this 'food limiting' procedure results in weight loss.

American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis

This literature review and the recommendations herein were prepared for the American Gastroenterological Association Clinical Practice Committee. The paper was approved by the Committee on May 16, 2004, and by the AGA Governing Board on September 23, 2004.