Endocrine and metabolic response to gastric bypass

Gastrointestinal genetic reprogramming of vitamin A metabolic pathways in response of Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) is one of the most performed bariatric surgical techniques. However, RYGB commonly results, as side effects, in nutritional deficiencies. This study aimed to examine changes in the expression of vitamin A pathway encoding genes in the gastrointestinal tract (GI) and to evaluate the potential mechanisms associated with hypovitaminosis A after RYGB. Intestinal biopsies were obtained through double-balloon endoscopy in 20 women with obesity (age 46.9±6.2 years; body mass index [BMI] 46.5±5.3 kg/m2 [mean±SD]) before and three months after RYGB (BMI, 38.2±4.2 kg/m2). Intestinal mucosal gene microarray analyses were performed in samples using a Human GeneChip 1.0 ST array (Affymetrix). Vitamin A intake was assessed from 7-day food records and serum retinol levels were evaluated by electrochemiluminescence immunoassay. Our results showed the following genes with significant downregulation (p≤0.05): LIPF (-0.60), NPC1L1 (-0.71), BCO1 (-0.45), and RBP4 (-0.13) in the duodenum; CD36 (-0.33), and ISX (-0.43) in the jejunum and BCO1 (-0.29) in the ileum. No significant changes in vitamin A intake were found (784±694 retinol equivalents [RE] pre-operative vs. 809±753 RE post-operative [mean±SD]). Although patients were routinely supplemented with 3500 international units IU/day (equivalent to 1050 μg RE/day) of oral retinol palmitate, serum concentrations were lower in the post-operative when compared to pre-operative period (0.35±0.14 μg/L vs. 0.52±0.33 μg/L, respectively - P=0.07), both within the normal range. After RYGB, the simultaneous change in expression of GI genes, may impair carotenoid metabolism in the enterocytes, formation of nascent chylomicrons and transport of retinol, resulting in lower availability of vitamin A.

Altered neural responsivity to food cues in relation to food preferences, but not appetite-related hormone concentrations after RYGB-surgery

BACKGROUND

After Roux-en-Y gastric bypass (RYGB) surgery, patients report a shift in food preferences away from high-energy foods.

OBJECTIVE

We aimed to elucidate the potential mechanisms underlying this shift in food preferences by assessing changes in neural responses to food pictures and odors before and after RYGB. Additionally, we investigated whether altered neural responsivity was associated with changes in plasma endocannabinoid and ghrelin concentrations.

DESIGN

19 RYGB patients (4 men; age 41 ± 10 years; BMI 41 ± 1 kg/m² before; BMI 36 ± 1 kg/m² after) participated in this study. Before and two months after RYGB surgery, they rated their food preferences using the Macronutrient and Taste Preference Ranking Task and BOLD fMRI responses towards pictures and odors of high-, and low-energy foods and non-food items were measured. Blood samples were taken to determine plasma endocannabinoid and ghrelin concentrations pre- and post-surgery.

RESULTS

Patients demonstrated a shift in food preferences away from high-fat/sweet and towards low-energy/savory food products, which correlated with decreased superior parietal lobule responsivity to high-energy food odor and a reduced difference in precuneus responsivity to high-energy versus low-energy food pictures. In the anteroventral prefrontal cortex (superior frontal gyrus) the difference in deactivation towards high-energy versus non-food odors reduced. The precuneus was less deactivated in response to all cues. Plasma concentrations of anandamide were higher after surgery, while plasma concentrations of other endocannabinoids and ghrelin did not change. Alterations in appetite-related hormone concentrations did not correlate with changes in neural responsivity.

CONCLUSIONS

RYGB leads to changed responsivity of the frontoparietal control network that orchestrates top-down control to high-energy food compared to low-energy food and non-food cues, rather than in reward related brain regions, in a satiated state. Together with correlations with the shift in food preference from high- to low-energy foods this indicates a possible role in new food preference formation.

Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass

OBJECTIVES

Vitamin B12 (B12) deficiency after Roux-en-Y gastric bypass (RYGB) is highly prevalent and may contribute to postoperative complications. Decreased production of intrinsic factor owing to gastric fundus removal is thought to have a major role, but other components of B12 metabolism may also be affected. We evaluated changes in the expression levels of multiple B12 pathway-encoding genes in gastrointestinal (GI) tissues to evaluate the potential roles in contributing to post-RYGB B12 deficiency.

METHODS

During double-balloon enteroscopy, serial GI biopsies were collected from 20 obese women (age, 46.9±6.2 years; body mass index, 46.5±5.3 kg/m2) with adult-onset type 2 diabetes (fasting plasma glucose ≥126 mg/dl; hemoglobin A1c≥6.5%) before and, at the same site, 3 months after RYGB. Gene expression levels were assessed by the Affymetrix Human GeneChip 1.0 ST microarray. Findings were validated by real-time quantitative PCR (RT-qPCR).

RESULTS

Gene expression levels with significant changes (P≤0.05) included: transcobalamin I (TCN1) in remnant (-1.914-fold) and excluded (-1.985-fold) gastric regions; gastric intrinsic factor (GIF) in duodenum (-0.725-fold); and cubilin (CUBN) in duodenum (+0.982-fold), jejunum (+1.311-fold), and ileum (+0.685-fold). Validation by RT-qPCR confirmed (P≤0.05) observed changes for TCN1 in the remnant gastric region (-0.132-fold) and CUBN in jejunum (+2.833-fold).

CONCLUSIONS

RYGB affects multiple pathway-encoding genes that may be associated with postoperative B12 deficiency. Decreased TCN1 levels seem to be the main contributing factor. Increased CUBN levels suggest an adaptive genetic reprogramming of intestinal tissue aiming to compensate for impaired intestinal B12 delivery.

Recent advances in the modification of taste and food preferences following bariatric surgery

There is a large body of evidence indicating that bariatric surgery provides durable weight loss and health benefits to patients who are obese and have comorbidities such as type 2 diabetes (T2D). However, there are still many questions related to mechanisms of metabolic improvement, predictors of success/failure, and long term consequences, which need to be answered. More recently, there has been a particular interest in the modulation of taste and food preferences that occurs after bariatric surgery and how this affects weight loss in different individuals. Animal models as well as human studies have shed some light on the role of taste in changing food preferences and how these changes may affect weight loss after surgery. The goal of this review is to discuss the physiological and behavioral consequences of bariatric surgery as a treatment for obesity and T2D, with particular emphasis on recent studies describing bariatric surgery-induced modifications in taste perception and food preferences.

Oxidative and endoplasmic reticulum stress in β-cell dysfunction in diabetes

The inability of pancreatic β-cells to make sufficient insulin to control blood sugar is a central feature of the aetiology of most forms of diabetes. In this review we focus on the deleterious effects of oxidative stress and endoplasmic reticulum (ER) stress on β-cell insulin biosynthesis and secretion and on inflammatory signalling and apoptosis with a particular emphasis on type 2 diabetes (T2D). We argue that oxidative stress and ER stress are closely entwined phenomena fundamentally involved in β-cell dysfunction by direct effects on insulin biosynthesis and due to consequences of the ER stress-induced unfolded protein response. We summarise evidence that, although these phenomenon can be driven by intrinsic β-cell defects in rare forms of diabetes, in T2D β-cell stress is driven by a range of local environmental factors including increased drivers of insulin biosynthesis, glucolipotoxicity and inflammatory cytokines. We describe our recent findings that a range of inflammatory cytokines contribute to β-cell stress in diabetes and our discovery that interleukin 22 protects β-cells from oxidative stress regardless of the environmental triggers and can correct much of diabetes pathophysiology in animal models. Finally we summarise evidence that β-cell dysfunction is reversible in T2D and discuss therapeutic opportunities for relieving oxidative and ER stress and restoring glycaemic control.

Short-term insulin requirements following gastric bypass surgery in severely obese women with type 1 diabetes

BACKGROUND

In severely obese type 2 diabetes patients, gastric bypass surgery (GB) reduces body mass index (BMI) and hemoglobin A1c (HbA1c) and allows reduced doses of insulin and other medications. Data regarding the effects of GB on severely obese patients with type 1 diabetes are limited.

METHODS

Severely obese women with type 1 diabetes (n = 9) were studied immediately before and after GB (7.7 ± 5.8 weeks, mean ± SD).

RESULTS

On average, GB reduced mean BMI by 11% and mean HbA1c by 0.9% (from 8.0 to 7.1%), with a parallel 38% decrease in basal insulin requirements (expressed per kilogram of body weight).

CONCLUSION

GB rapidly decreased BMI, HbA1c, and insulin requirements in severely obese women with type 1 diabetes. However, physiologic insulin replacement remains necessary in patients with type 1 diabetes.

Is there a role for enhanced recovery after laparoscopic bariatric surgery? Preliminary results from a specialist obesity treatment center

BACKGROUND

There has been a relative lack of research on the effect of enhanced recovery in the context of morbid obesity surgery.

OBJECTIVES

To determine if the application of enhanced recovery after surgery (ERAS) principles can contribute to reduce postoperative hospital length of stay after bariatric surgery, controlling for other factors that may influence safe discharge on the first postoperative day.

SETTING

University teaching hospital, United Kingdom.

METHODS

Between February 2011 and December 2014, prospectively collected data on all patients undergoing laparoscopic bariatric surgery under the care of a single surgeon were reviewed. From January 2012, all patients were enrolled in an ERAS protocol and were assessed for fitness for early discharge (within 24 hr from the operation). Baseline patient characteristics and additional concomitant procedures data were compared for patients treated before and after implementation of the ERAS protocol; 30-day readmission data were analyzed for patients discharged on the first postoperative day and those discharged later. The effect of the implementation of the ERAS protocol on discharge on the first postoperative day was analyzed using multivariate analysis, while taking into account the effects of potential confounders (e.g., age, gender, American Society of Anesthesiologists [ASA] grade, concomitant surgical procedures, etc.).

RESULTS

Two-hundred and eighty-eight consecutive patients underwent bariatric surgery. Of these, 278 (96.5%) were potentially suitable for early discharge, while 10 (3.5%) patients developed an acute postoperative complication that delayed discharge irrespective of the effect of ERAS. All these patients required a reoperation within 48 hours and therefore were not considered suitable for early discharge and were not included in the statistical analysis. During the entire study period, 100 of 278 (36%) patients were discharged on the first postoperative day, 28.5% after laparoscopic Roux-en-Y gastric bypass (LRYGB) and 60.9% after laparoscopic sleeve gastrectomy (LSG); 178 of 278 (64%) patients were discharged after ≥ 2 days (mean: 2.58, range: 2-5). After implementation of the ERAS protocol in January 2012, the rate of patients discharged on the first postoperative day increased significantly from 1.6% to 39.7% after LRYGB (P<.01). Early discharge increased from 50% to 67.5% after LSG; although this change did not reach statistical significance (P = .294), it nevertheless represents a clinically relevant result. Four (4%) patients were readmitted after having been discharged on the first postoperative day, 10 (5.3%) patients after having been discharged ≥ 2 postoperative days. This difference was not statistically significant (P = .620).

CONCLUSIONS

The implementation of an enhanced recovery program after bariatric surgery is feasible, well tolerated, and can significantly reduce the length of hospital stay without increasing readmission rates. Controlling for several possible confounders, implementation of the ERAS protocol remained the strongest predictor of discharge on the first postoperative day after laparoscopic bariatric surgery.

Induced ablation of ghrelin cells in adult mice does not decrease food intake, body weight, or response to high-fat diet

Injection of the peptide hormone ghrelin stimulates food intake in mice and humans. However, mice born without ghrelin demonstrate no significant loss of appetite. This paradox suggests either that compensation develops in mice born without ghrelin or that ghrelin is not essential for appetite control. To distinguish these possibilities, we generated transgenic mice (Ghrl-DTR) that express the diphtheria toxin receptor in ghrelin-secreting cells. Injection of diphtheria toxin in adulthood ablated ghrelin cells and reduced plasma ghrelin by 80%-95%. Ghrelin cell-ablated mice exhibited no loss of appetite or body weight and no resistance to a high-fat diet. To stimulate food intake in mice by ghrelin injection, we had to raise plasma levels many-fold above normal. Like germline ghrelin-deficient mice, the ghrelin cell-ablated mice developed profound hypoglycemia when subjected to prolonged calorie restriction, confirming that ghrelin acts to maintain blood glucose under famine conditions.

Potential mechanisms by which bariatric surgery improves systemic metabolism

Over the past several decades, excessive body weight has become a major health concern. As the obesity epidemic continues to expand, metabolic disorders associated with excess body weight, including type 2 diabetes, dyslipidemia, hypertension, and cardiovascular disease, have exponentially increased. Dysregulation of satiety hormones and factors that regulate long-term energy storage can disrupt normal metabolic functions and lead to excess body fat. While diet and exercise seem to provide a logical means for weight loss, an unhealthy lifestyle coupled to responses initiated by perceived energy deficit impede sustained long term weight loss. Furthermore, because of the additional lack of effective pharmaceutical interventions to treat excess body weight, patients with severe obesity resort to bariatric surgery as an effective alternative for treatment of obesity and resolution of its associated comorbidities. Interestingly, the precise method by which bariatric surgery promotes rapid improvement in systemic metabolism and long-term weight loss remains incompletely understood and may vary between procedures. Multiple mechanisms likely contribute to the improved glucose metabolism seen after bariatric surgery, including caloric restriction, changes in the enteroinsular axis, alterations in the adipoinsular axis, release of nutrient-stimulated hormones from endocrine organs, stimulation from the nervous system, and psychosocial aspects including a dramatic improvement in quality of life. The current review will highlight the potential contribution of these responses to the improvement in systemic energy metabolism elicited by bariatric surgery.

Total knee arthroplasty in morbidly obese patients treated with bariatric surgery: a comparative study

Our objective was to compare outcomes (anesthesia time, total operative time, tourniquet time, duration of hospital stay, 90-day complication rate, and transfusion rates) of patients with total knee arthroplasty (TKA) who underwent bariatric surgery before or after TKA. One hundred twenty-five patients were included: TKA before bariatric surgery (group 1; n = 39), TKA within 2 years of bariatric surgery (group 2; n = 25), and TKA more than 2 years after bariatric surgery (group 3; n = 61). Patients with TKA more than 2 years after bariatric surgery had shorter anesthesia and total operative and tourniquet times than other groups; differences were significant between groups. Ninety-day complication and transfusion rates approached but did not meet statistical significance. Ninety-day complication rates and duration of hospital stay did not differ significantly between the 3 groups. The level of evidence was level II (cohort study).

Effect of bariatric surgery on peripheral flow-mediated dilation and coronary microvascular function

BACKGROUND AND AIMS

To assess the effects of bariatric surgery (BS) on peripheral endothelial function and on coronary microvascular dilator function.

METHODS AND RESULTS

We studied 50 morbidly obese patients (age 38 ± 9, 13 M) who underwent BS and 20 comparable obese controls (age 41 ± 11, 6 M) without any evidence of cardiovascular disease. Peripheral vascular dilator function was assessed by brachial artery diameter changes in response to post-ischemic forearm hyperaemia (flow-mediated dilation, FMD). Coronary microvascular function was assessed by measuring coronary blood flow (CBF) velocity response to i.v. adenosine and to cold pressor test (CPT) in the left anterior descending coronary artery by transthoracic Doppler echocardiography. The tests were performed at baseline and at 3-month follow-up. At baseline, FMD and CBF response to adenosine and CPT were similar in the 2 groups. Compared to baseline, FMD at follow-up improved significantly in BS patients (5.9 ± 2.7% to 8.8 ± 2.4%, p < 0.01), but not in controls (6.3 ± 3.2% vs. 6.4 ± 3.1%, p = 0.41). Similarly, a significant improvement of CBF response to adenosine (1.63 ± 0.47 to 2.45 ± 0.57, p < 0.01) and to CPT (1.43 ± 0.26 to 2.13 ± 0.55, p < 0.01) was observed in BS patients but not in controls (1.55 ± 0.38 vs. 1.53 ± 0.37, p = 0.85; and 1.37 ± 0.26 vs. 1.34 ± 0.21, p = 0.48, respectively). The favourable vascular effects of BS were similar independently of the presence and changes of other known cardiovascular risk factors and of basal values and changes of serum C-reactive protein levels.

CONCLUSIONS

Our data show that, in morbidly obese patients, together with peripheral endothelial function, BS also improves coronary microvascular function. These effects suggest global improvement of vascular function which can contribute significantly to the reduction of cardiovascular risk by BS reported in previous studies.

Examining the link between bariatric surgery, bone loss, and osteoporosis: a review of bone density studies

As the popularity of bariatric surgery to treat morbid obesity has risen, so has a concern of increased skeletal fragility secondary to accelerated bone loss following bariatric procedures. We reviewed cross-sectional and prospective literature reporting bone density outcomes following bariatric surgical treatment for morbid obesity. Prospective research provides evidence of hip and lumbar spine areal bone mineral density (aBMD) reductions primarily in women despite calcium and vitamin D supplementation. Femoral neck aBMD declines of 9-11% and lumbar spine aBMD reductions up to 8% were observed at the first post-operative year following malabsorptive procedures. Mean T- and Z-scores up to 25 years following surgery remained within normal and healthy ranges. Of those studies reporting development of osteoporosis following gastric bypass, one woman became osteoporotic after 1 year. Despite observed bone loss in the hip region post-surgery, data do not conclusively support increased incidence of osteoporosis or increased fracture risk in post-bariatric patients. However, given the limitations of dual energy X-ray absorptiometry technology in this population and the relative lack of long-term prospective studies that include control populations, further research is needed to provide conclusive evidence regarding fracture outcomes in this population.

Goettingen Minipigs (GMP): Comparison of Two Different Models for Inducing Diabetes

PURPOSE

Preclinical experiments on large animals are indispensable for evaluating the effectiveness of diabetes therapies. Miniature swine are well suited for such studies due to their physiological and pathophysiological responses.

METHODS

We compare two methods for inducing diabetes in Goettingen minipigs (GMP), in five with the beta cell toxin streptozotocin (STZ) and in five other GMP by total pancreatectomy (PE). Glucose homeostasis was assessed with the intravenous glucose-tolerance test (IVGTT) and continual monitoring of interstitial glucose levels. At conclusion of the observation period, the pancreata were examined histologically. Three non-diabetic GMP served as control group.

RESULTS

The IVGTT revealed markedly diabetic profiles in both GMP groups. STZ-GMP were found to harbor residual C-peptides and scattered insulin-positive cells in the pancreas. PE-GMP survived the total pancreatectomy only with intensive postoperative care.

CONCLUSIONS

Although both methods reliably induced diabetes in GMP, the PE-GMP clearly had more health problems and required a greater expenditure of time and resources. The PE-GMP model, however, was better at eliminating endogenous insulin and C-peptide than the STZ-GMP model.

Changes in gastrointestinal hormones and leptin after Roux-en-Y gastric bypass surgery

BACKGROUND

Roux-en-Y gastric bypass (RYGB) imparts long-term weight loss, the mechanisms for which are not well understood. Changes in leptin and gastrointestinal (GI) hormones, including glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and ghrelin, may contribute to the relative success of RYGB compared with conventional weight loss methods. This study evaluated changes in GI hormones and leptin post-RYGB. The study also evaluated whether GI hormones differed after a short-term dose of protein or fat.

METHODS

GLP-1, PYY, ghrelin, and leptin were assessed in 16 women before RYGB and up to 1 year after RYGB. Plasma was collected before and at several times after a short-term equicaloric dose of protein or fat.

RESULTS

GLP-1 area under the curve (AUC) increased at week 6 and 1 year in the fat beverage (FAT-BEV) group compared with baseline. PYY AUC remained elevated at 1 year in the FAT-BEV group. Ghrelin AUC decreased at week 2, week 6, and 1 year in the protein beverage (PRO-BEV) group compared with baseline. Ghrelin AUC was lower in the PRO-BEV group compared with the FAT-BEV group at week 6. Fasted leptin decreased at all visits in both groups and was lower in the FAT-BEV group compared with the PRO-BEV group at 1 year.

CONCLUSIONS

Changes from baseline were evident for all GI hormones and leptin; some differences were evident soon after surgery (ghrelin, leptin), whereas others were maintained long term (GLP-1, PYY, ghrelin, leptin). In response to a short-term stimulus, protein suppressed ghrelin and fat potently stimulated GLP-1 and PYY. Future work in this area is warranted.

Prospective study of self-reported diabetes and risk of upper gastrointestinal cancers

BACKGROUND

Although gastric noncardia adenocarcinoma (GNCA) incidence rates in the United States have decreased, the rates of gastric cardia adenocarcinoma (GCA) and esophageal adenocarcinoma (EADC) have increased. Obesity increases the risks of GCA and EADC, and the associations may be partially mediated by insulin resistance. A few case-control studies have shown an association between diabetes and an increased risk of EADC.

METHODS

We prospectively examined the association between diabetes and upper gastrointestinal (UGI) cancers in a cohort of 469,448 people in the United States, ages 50 to 71 at baseline. Cox proportional hazards regression was used to estimate the HR and 95% CI for diabetes and UGI cancers, controlling for multiple potential confounders, including body mass index (BMI).

RESULTS

We observed no association of self-reported diabetes with risk of EADC, HR (95% CI) = 0.98 (0.73-1.31), esophageal squamous cell carcinoma (ESCC), HR (95% CI) = 1.02 (0.60-1.74), or GNCA, HR (95% CI) = 0.98 (0.70-1.37). However, diabetes was significantly associated with an increased risk of GCA, HR (95% CI) = 1.89 (1.43-2.50). The significant association between diabetes and risk of GCA remained after adjustment for BMI, HR (95% CI) = 1.70 (1.28-2.26) and did not differ by BMI strata (P(interaction) = 0.83). The significant association was unchanged when restricting to only overweight subjects (BMI 25 to ≤30), HR (95% CI) = 1.83 (1.18-2.85).

CONCLUSIONS

We found a significant association between self-reported diabetes and increased risk of GCA.

IMPACT

Our results suggest that the metabolic and hormonal changes related to diabetes may play a role in the etiology of GCA independently from BMI.

Impact of weight change, secular trends and ageing on cardiovascular risk factors: 10-year experiences from the SOS study

OBJECTIVE

Many short-term studies indicate that 5% weight loss in the obese is enough to induce significant improvements of cardiovascular risk factors. However, it is not known what degree of weight loss is required to improve risk factors over a more extended period of time or how ageing and secular trends per se are influencing risk factors during long-term follow-up.

METHODS

Patients examined after 10 years in the intervention study Swedish Obese Subjects were used for the current analysis. Surgically treated subjects (n=959) and conventionally treated obese controls (n=842) were pooled to obtain a study group with a large range of weight changes. The patients were divided in 11 groups based on the amount of weight change. Analysis of covariance was used to determine the necessary weight change over 10 years for a significant alteration of a risk factor. In a linear regression of risk factor change by weight change, the y intercept was interpreted as the effect of 10 years ageing and secular trends on a given risk factor in the absence of weight change.

RESULTS

The necessary weight loss for significant improvement of risk factors ranged from 10 to 44 kg. At zero weight change, 10 years of ageing was associated with significant increases in systolic blood pressure, pulse pressure, high-density lipoprotein cholesterol and glucose, and with significant decreases in diastolic blood pressure, total cholesterol, triglycerides and insulin.

CONCLUSIONS

The necessary weight loss to maintain a favourable effect on risk factors in an obese population is larger than previously indicated by short-term studies. Treatment effects are influenced by non-weight change-dependant shifts in risk factor levels.

The importance of caloric restriction in the early improvements in insulin sensitivity after Roux-en-Y gastric bypass surgery

OBJECTIVE

Many of the metabolic benefits of Roux-en-Y gastric bypass (RYGB) occur before weight loss. In this study we investigated the influence of caloric restriction on the improvements in the metabolic responses that occur within the 1st week after RYGB. RESEARCH METHODS AND DESIGN: A mixed meal was administered to nine subjects before and after RYGB (average 4 +/- 0.5 days) and to nine matched, obese subjects before and after 4 days of the post-RYGB diet.

RESULTS

Weight loss in both groups was minimal; the RYGB subjects lost 1.4 +/- 5.3 kg (P = 0.46) vs. 2.2 +/- 1.0 kg (P = 0.004) in the calorically restricted group. Insulin resistance (homeostasis model assessment of insulin resistance) improved with both RYGB (5.0 +/- 3.1 to 3.3 +/- 2.1; P = 0.03) and caloric restriction (4.8 +/- 4.1 to 3.6 +/- 4.1; P = 0.004). The insulin response to a mixed meal was blunted in both the RYGB and caloric restriction groups (113 +/- 67 to 65 +/- 33 and 85 +/- 59 to 65 +/- 56 nmol x l(-1) x min(-1), respectively; P < 0.05) without a change in the glucose response. Glucagon-like peptide 1 levels increased (9.2 +/- 8.6 to 12.2 +/- 5.5 pg x l(-1) x min(-1); P = 0.04) and peaked higher (45.2 +/- 37.3 to 84.8 +/- 33.0 pg/ml; P = 0.01) in response to a mixed meal after RYGB, but incretin responses were not altered after caloric restriction.

CONCLUSIONS

These data suggest that an improvement in insulin resistance in the 1st week after RYGB is primarily due to caloric restriction, and the enhanced incretin response after RYGB does not improve postprandial glucose homeostasis during this time.

The evolving world of GLP-1 agonist therapies for type 2 diabetes

The glucagon-like peptide-1 (GLP-1) agonist drugs have attractions as a treatment for type 2 diabetes since they positively alter a number of key pathophysiological defects. These include increasing insulin release, reducing glucagon release, slowing gastric emptying and reducing food intake. In numerous clinical trials these agents have been shown to reduce DCCT-aligned HbA(1c) between 0.8% and 1.1% in patients with moderately controlled type 2 diabetes, whilst also being associated with some weight loss. Whilst medium-term safety and side-effect profiles are now well established, there are as yet no long-term studies on the safety of this group of drugs. The place of the GLP-1 agonists in the treatment paradigm for type 2 diabetes will evolve over the next decade.

Diabetes: treatment of type 2 diabetes mellitus with bariatric surgery

Gastrointestinal surgery may ameliorate glycemic control in type 2 diabetes mellitus within days to weeks--an effect that cannot be explained solely by the changes in food intake and body weight following gastric bypass. should clinicians, therefore, implement bariatric procedures to treat type 2 diabetes mellitus in patients who do not meet current obesity-based criteria for surgery?

Integrating GHS into the Ghrelin System

Oligopeptide derivatives of metenkephalin were found to stimulate growth-hormone (GH) release directly by pituitary somatotrope cells in vitro in 1977. Members of this class of peptides and nonpeptidyl mimetics are referred to as GH secretagogues (GHSs). A specific guanosine triphosphatate-binding protein-associated heptahelical transmembrane receptor for GHS was cloned in 1996. An endogenous ligand for the GHS receptor, acylghrelin, was identified in 1999. Expression of ghrelin and homonymous receptor occurs in the brain, pituitary gland, stomach, endothelium/vascular smooth muscle, pancreas, placenta, intestine, heart, bone, and other tissues. Principal actions of this peptidergic system include stimulation of GH release via combined hypothalamopituitary mechanisms, orexigenesis (appetitive enhancement), insulinostasis (inhibition of insulin secretion), cardiovascular effects (decreased mean arterial pressure and vasodilation), stimulation of gastric motility and acid secretion, adipogenesis with repression of fat oxidation, and antiapoptosis (antagonism of endothelial, neuronal, and cardiomyocyte death). The array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development.

Feeding regulates the expression of pancreatic genes in gastric mucosa

The ineffective short-term control of feeding behavior compromises energy homeostasis and can lead to obesity. The gastrointestinal tract secretes several regulatory peptides. However, little is known about the stomach peptide contribution to the acute regulation of intake. In an attempt to identify new gastric signals, the serial analysis of gene expression (SAGE) method was used for the transcription profiling of stomach mucosa in 7 groups of mice: fasting and sacrificed 30 minutes, 1 hour, 3 hours after a low-fat (LF) or high-fat (HF) ad libitum meal. In total, 35 genes were differentially modulated by LF and HF meals compared to fasting, including 15 mRNAs coding for digestive enzymes/secretory proteins, and 10 novel transcripts. Although the basic expression profile did not undergo substantial variations, both LF and HF meals influenced the transcription. This study represents the first global analysis of stomach transcriptome as induced by different nutritional stimuli. Further studies including the characterization of novel genes may help to identify new targets for the therapy and prevention of obesity.