Tripeptide gut hormone infusion does not alter food preferences or sweet taste function in volunteers with obesity and prediabetes/diabetes but promotes restraint eating: A secondary analysis of a randomized single-blind placebo-controlled study

AIMS

To investigate whether the elevation in postprandial concentrations of the gut hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM) and peptide YY (PYY) accounts for the beneficial changes in food preferences, sweet taste function and eating behaviour after Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

This was a secondary analysis of a randomized single-blind study in which we infused GLP-1, OXM, PYY (GOP) or 0.9% saline subcutaneously for 4 weeks in 24 subjects with obesity and prediabetes/diabetes, to replicate their peak postprandial concentrations, as measured at 1 month in a matched RYGB cohort (ClinicalTrials.gov NCT01945840). A 4-day food diary and validated eating behaviour questionnaires were completed. Sweet taste detection was measured using the method of constant stimuli. Correct sucrose identification (corrected hit rates) was recorded, and sweet taste detection thresholds (EC50s: half maximum effective concencration values) were derived from concentration curves. The intensity and consummatory reward value of sweet taste were assessed using the generalized Labelled Magnitude Scale.

RESULTS

Mean daily energy intake was reduced by 27% with GOP but no significant changes in food preferences were observed, whereas a reduction in fat and increase in protein intake were seen post-RYGB. There was no change in corrected hit rates or detection thresholds for sucrose detection following GOP infusion. Additionally, GOP did not alter the intensity or consummatory reward value of sweet taste. A significant reduction in restraint eating, comparable to the RYGB group was observed with GOP.

CONCLUSION

The elevation in plasma GOP concentrations after RYGB is unlikely to mediate changes in food preferences and sweet taste function after surgery but may promote restraint eating.

The Metabolomic Effects of Tripeptide Gut Hormone Infusion Compared to Roux-en-Y Gastric Bypass and Caloric Restriction

CONTEXT

The gut-derived peptide hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM), and peptide YY (PYY) are regulators of energy intake and glucose homeostasis and are thought to contribute to the glucose-lowering effects of bariatric surgery.

OBJECTIVE

To establish the metabolomic effects of a combined infusion of GLP-1, OXM, and PYY (tripeptide GOP) in comparison to a placebo infusion, Roux-en-Y gastric bypass (RYGB) surgery, and a very low-calorie diet (VLCD).

DESIGN AND SETTING

Subanalysis of a single-blind, randomized, placebo-controlled study of GOP infusion (ClinicalTrials.gov NCT01945840), including VLCD and RYGB comparator groups.

PATIENTS AND INTERVENTIONS

Twenty-five obese patients with type 2 diabetes or prediabetes were randomly allocated to receive a 4-week subcutaneous infusion of GOP (n = 14) or 0.9% saline control (n = 11). An additional 22 patients followed a VLCD, and 21 underwent RYGB surgery.

MAIN OUTCOME MEASURES

Plasma and urine samples collected at baseline and 4 weeks into each intervention were subjected to cross-platform metabolomic analysis, followed by unsupervised and supervised modeling approaches to identify similarities and differences between the effects of each intervention.

RESULTS

Aside from glucose, very few metabolites were affected by GOP, contrasting with major metabolomic changes seen with VLCD and RYGB.

CONCLUSIONS

Treatment with GOP provides a powerful glucose-lowering effect but does not replicate the broader metabolomic changes seen with VLCD and RYGB. The contribution of these metabolomic changes to the clinical benefits of RYGB remains to be elucidated.

Weight Loss by Low-Calorie Diet Versus Gastric Bypass Surgery in People With Diabetes Results in Divergent Brain Activation Patterns: A Functional MRI Study

OBJECTIVE

Weight loss achieved with very-low-calorie diets (VLCDs) can produce remission of type 2 diabetes (T2D), but weight regain very often occurs with reintroduction of higher calorie intakes. In contrast, bariatric surgery produces clinically significant and durable weight loss, with diabetes remission that translates into reductions in mortality. We hypothesized that in patients living with obesity and prediabetes/T2D, longitudinal changes in brain activity in response to food cues as measured using functional MRI would explain this difference.

RESEARCH DESIGN AND METHODS

Sixteen participants underwent gastric bypass surgery, and 19 matched participants undertook a VLCD (meal replacement) for 4 weeks. Brain responses to food cues and resting-state functional connectivity were assessed with functional MRI pre- and postintervention and compared across groups.

RESULTS

We show that Roux-en-Y gastric bypass surgery (RYGB) results in three divergent brain responses compared with VLCD-induced weight loss: 1) VLCD resulted in increased brain reward center food cue responsiveness, whereas in RYGB, this was reduced; 2) VLCD resulted in higher neural activation of cognitive control regions in response to food cues associated with exercising increased cognitive restraint over eating, whereas RYGB did not; and 3) a homeostatic appetitive system (centered on the hypothalamus) is better engaged following RYGB-induced weight loss than VLCD.

CONCLUSIONS

Taken together, these findings point to divergent brain responses to different methods of weight loss in patients with diabetes, which may explain weight regain after a short-term VLCD in contrast to enduring weight loss after RYGB.

The Importance of Interpreting Urine Calcium:Creatinine Ratio in PHPT Within Ethnic Context

A 56-year-old Afro-Caribbean lady was found to have incidental hypercalcaemia on routine GP investigations. Tiredness was the only elicitable hypercalcaemic symptom and aside from early menopause at age 40, she had no significant past medical or family history. Examination was unremarkable. Blood results showed a raised adjusted calcium 2.68mmol/L (2.2–2.6), normal phosphate 1.06mmol/L (0.80–1.50), raised parathyroid hormone (PTH) 14.1pmol/L (1.6–7.2) and low 25-hydroxyvitamin D 28.1nmol/L (70–150).

She had osteopaenia of the femora and left radius on DEXA scan but no nephrocalcinosis on renal ultrasound. On initial investigation, her urinary calcium output was low at 1.55mmol/day resulting in a 24h calcium:creatinine ratio (UCCR) of 0.0065. Although suggestive of Familial Hypocalciuric Hypercalcaemia (FHH), her notable Vitamin D deficiency was considered to contribute to the observed hypocalciuria. After Vitamin D repletion, a repeat UCCR improved to 0.012, however, remained in the indeterminate range. No known pathogenic variant was identified on genetic analysis for FHH.

Her PTH and Calcium levels remained persistently high within 9.7–17.1pmol/L and 2.65-2.82mmol/L respectively, suggestive of Primary Hyperparathyroidism (PHPT) given the end organ damage and negative genetic studies. Based on her symptom of fatigue, osteopaenia at a young age and hypercalcaemia, localisation studies were arranged which showed no definitive evidence of a parathyroid adenoma and explorative surgery was planned.

The negative genetic testing, PTH level 17.1pmol/L, osteopaenia, low-normal magnesium and phosphate level collectively support a diagnosis of PHPT in this case, despite a low UCCR which however is observed in some PHPT patients. Indeed, a lower UCCR ratio has been reported in the healthy Afro-Carribean population across all age groups, as well as in Afro-Carribean patients with PHPT [1]. The underlying mechanism for this is yet to be determined but may be due to increased renal sensitivity to PTH or altered activity of the tubular calcium reabsorptive pathways. One can further speculate regarding an evolutionary reason behind a protective homeostatic system favouring renal calcium reabsorption over excretion in this frequently vitamin D deficient population.

Clinical practice relies heavily on the use of UCCR in aiding the biochemical differentiation of PHPT and FHH. However, as this case highlights, its use can be misleading in Afro-Carribean patients and therefore should be interpreted within an ethnic context.

References: Taha W., Singh N., Flack J. M., Abou-Samra A. B. Low urine calcium excretion in African American patients with Primary Hyperparathyroidism. Endocr Pract. 2011; 17: 867–872

Roux-en-Y Gastric Bypass Increases Glycemic Variability and Time in Hypoglycemia in Patients With Obesity and Prediabetes or Type 2 Diabetes: A Prospective Cohort Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) is an established treatment for type 2 diabetes and obesity. The study objective was to establish RYGB's effects on glycemic variability (GV) and hypoglycemia.

RESEARCH DESIGN AND METHODS

This was a prospective observational study of 10 participants with obesity and prediabetes or type 2 diabetes who underwent RYGB. Patients were studied before RYGB (Pre) and 1 month, 1 year, and 2 years postsurgery with continuous glucose measurement (CGM). A mixed-meal test (MMT) was conducted at Pre, 1 month, and 1 year.

RESULTS

After RYGB, mean CGM decreased (at 1 month, 1 year, and 2 years), and GV increased (at 1 year and 2 years). Five of the 10 participants had a percent time in range (%TIR) <3.0 mmol/L (54 mg/dL) greater than the international consensus target of 1% at 1 or 2 years. Peak glucagon-like peptide-1 (GLP-1) and glucagon area under the curve during MMT were positively and negatively associated, respectively, with contemporaneous %TIR <3.0 mmol/L.

CONCLUSIONS

Patients undergoing RYGB are at risk for development of postbariatric hypoglycemia due to a combination of reduced mean glucose, increased GV, and increased GLP-1 response.

Acute Effects of Glucagon on Reproductive Hormone Secretion in Healthy Men

CONTEXT

Glucagon increases energy expenditure; consequently, glucagon receptor agonists are in development for the treatment of obesity. Obesity negatively affects the reproductive axis, and hypogonadism itself can exacerbate weight gain. Therefore, knowledge of the effects of glucagon receptor agonism on reproductive hormones is important for developing therapeutics for obesity; but reports in the literature about the effects of glucagon receptor agonism on the reproductive axis are conflicting.

OBJECTIVE

The objective of this work is to investigate the effect of glucagon administration on reproductive hormone secretion in healthy young men.

DESIGN

A single-blinded, randomized, placebo-controlled crossover study was conducted.

SETTING

The setting of this study was the Clinical Research Facility, Imperial College Healthcare NHS Trust.

PARTICIPANTS

Eighteen healthy eugonadal men (mean ± SEM: age 25.1 ± 1.0 years; body mass index 22.5 ± 0.4 kg/m2; testosterone 21.2 ± 1.2 nmol/L) participated in this study.

INTERVENTION

An 8-hour intravenous infusion of 2 pmol/kg/min glucagon or rate-matched vehicle infusion was administered.

MAIN OUTCOME MEASURES

Luteinizing hormone (LH) pulsatility; LH, follicle-stimulating hormone (FSH), and testosterone levels were measured.

RESULTS

Although glucagon administration induced metabolic effects (insulin area under the curve: vehicle 1065 ± 292 min.µU/mL vs glucagon 2098 ± 358 min.µU/mL, P < .001), it did not affect LH pulsatility (number of LH pulses/500 min: vehicle 4.7 ± 0.4, glucagon 4.2 ± 0.4, P = .22). Additionally, there were no significant differences in circulating LH, FSH, or testosterone levels during glucagon administration compared with vehicle administration.

CONCLUSIONS

Acute administration of a metabolically active dose of glucagon does not alter reproductive hormone secretion in healthy men. These data are important for the continued development of glucagon-based treatments for obesity.

[18F]Fluciclatide PET as a biomarker of response to combination therapy of pazopanib and paclitaxel in platinum-resistant/refractory ovarian cancer

BACKGROUND

Angiogenesis is a driver of platinum resistance in ovarian cancer. We assessed the effect of combination pazopanib and paclitaxel followed by maintenance pazopanib in patients with platinum-resistant/refractory ovarian cancer. Integrins αvβ3 and αvβ5 are both upregulated in tumor-associated vasculature. [18F]Fluciclatide is a novel PET tracer that has high affinity for integrins αvβ3/5, and was used to assess the anti-angiogenic effect of pazopanib.

PATIENTS AND METHODS

We conducted an open-label, phase Ib study in patients with platinum-resistant/refractory ovarian cancer. Patients received 1 week of single-agent pazopanib (800 mg daily) followed by combination therapy with weekly paclitaxel (80 mg/m2). Following completion of 18 weeks of combination therapy, patients continued with single-agent pazopanib until disease progression. Dynamic [18F]fluciclatide-PET imaging was conducted at baseline and after 1 week of pazopanib. Response (RECIST 1.1), toxicities, and survival outcomes were recorded. Circulating markers of angiogenesis were assessed with therapy.

RESULTS

Fourteen patients were included in the intention-to-treat analysis. Complete and partial responses were seen in seven patients (54%). Median progression-free survival (PFS) was 10.63 months, and overall survival (OS) was 18.5 months. Baseline [18F]fluciclatide uptake was predictive of long PFS. Elevated baseline circulating angiopoietin and fibroblast growth factor (FGF) were predictive of greater reduction in SUV60,mean following pazopanib. Kinetic modeling of PET data indicated a reduction in K1 and Ki following pazopanib indicating reduced radioligand delivery and retention.

CONCLUSIONS

Combination therapy followed by maintenance pazopanib is effective and tolerable in platinum-resistant/refractory ovarian cancer. [18F]Fluciclatide-PET uptake parameters predict clinical outcome with pazopanib therapy indicating an anti-angiogenic response.

Effects of Glucagon-like Peptide-1 on the Reproductive Axis in Healthy Men

CONTEXT

Glucagon-like peptide-1 (GLP-1) potently reduces food intake and augments glucose-stimulated insulin secretion. Recent animal data suggest that GLP-1 may also influence reproduction. As GLP-1 receptor agonists are currently widely used in clinical practice to treat obesity/type 2 diabetes, it is necessary to determine the effects of GLP-1 on the reproductive system in humans.

OBJECTIVE

To investigate the effects of GLP-1 administration on the reproductive axis in humans.

DESIGN

Single-blind, randomized, placebo-controlled crossover study.

SETTING

Clinical Research Facility, Imperial College Healthcare NHS Trust.

PARTICIPANTS

Eighteen healthy men (mean age 24.7 ± 0.1years, mean BMI 22.1 ± 0.4kg/m2).

INTERVENTION

Eight-hour intravenous infusion of 0.8 pmol/kg/min GLP-1 or rate-matched vehicle infusion.

MAIN OUTCOME MEASURES

Number of luteinizing hormone (LH) pulses, LH, follicle-stimulating hormone (FSH), and testosterone levels.

RESULTS

The number of LH pulses (number of LH pulses/500 min: vehicle 4.2 ± 0.4, GLP-1 4.5 ± 0.3, P = 0.46), LH area under the curve (AUC) (vehicle 1518 ± 88min.IU/L, GLP-1 1524 ± 101min.IU/L, P = 0.95), follicle-stimulating hormone AUC (vehicle 1210 ± 112 min IU/L, GLP-1 1216 ± 112 min IU/L, P = 0.86), and testosterone AUC (vehicle 10893 ± 615 min nmol/L, GLP-1 11088 ± 792 min nmol/L, P = 0.77) did not significantly differ during vehicle and GLP-1 administration. Glucagon-like peptide-1 significantly reduced food intake (vehicle 15.7 ± 1.3 kcal/kg, GLP-1 13.4 ± 1.3 kcal/kg, P = 0.01).

CONCLUSIONS

In contrast to the animal literature, our data demonstrate that acute GLP-1 administration does not affect reproductive hormone secretion in healthy men.

Proglucagon peptide secretion profiles in type 2 diabetes before and after bariatric surgery: 1-year prospective study

INTRODUCTION

Hyperglucagonemia is a key pathophysiological driver of type 2 diabetes. Although Roux-en-Y gastric bypass (RYGB) is a highly effective treatment for diabetes, it is presently unclear how surgery alters glucagon physiology. The aim of this study was to characterize the behavior of proglucagon-derived peptide (glucagon, glucagon-like peptide-1 (GLP-1), oxyntomodulin, glicentin) secretion after RYGB surgery.

RESEARCH DESIGN AND METHODS

Prospective study of 19 patients with obesity and pre-diabetes/diabetes undergoing RYGB. We assessed the glucose, insulin, GLP-1, glucose-dependent insulinotropic peptide (GIP), oxyntomodulin, glicentin and glucagon responses to a mixed-meal test (MMT) before and 1, 3 and 12 months after surgery. Glucagon was measured using a Mercodia glucagon ELISA using the 'Alternative' improved specificity protocol, which was validated against a reference liquid chromatography combined with mass spectrometry method.

RESULTS

After RYGB, there were early improvements in fasting glucose and glucose tolerance and the insulin response to MMT was accelerated and amplified, in parallel to significant increases in postprandial GLP-1, oxyntomodulin and glicentin secretion. There was a significant decrease in fasting glucagon levels at the later time points of 3 and 12 months after surgery. Glucagon was secreted in response to the MMT preoperatively and postoperatively in all patients and there was no significant change in this postprandial secretion. There was no significant change in GIP secretion.

CONCLUSIONS

There is a clear difference in the dynamics of secretion of proglucagon peptides after RYGB. The reduction in fasting glucagon secretion may be one of the mechanisms driving later improvements in glycemia after RYGB.

TRIAL REGISTRATION NUMBER

NCT01945840.

Effects of Peptide YY on the Hypothalamic-Pituitary-Gonadal Axis in Healthy Men

CONTEXT

Central and peripheral administration of peptide YY (PYY) has potent anorectic effects, and PYY analogs are under development as antiobesity treatments. Recent animal data suggest PYY may also influence the reproductive axis; however the effects of PYY on the human reproductive system are unknown.

OBJECTIVE

To investigate the effects of PYY administration on the reproductive axis in healthy young men.

DESIGN

Single-blind, randomized, placebo-controlled crossover study.

SETTING

Clinical Research Facility, Imperial College Healthcare NHS Trust.

PARTICIPANTS

Eighteen healthy eugonadal men (mean age 24.1 ± 0.9 years, mean body mass index 22.2 ± 0.4 kg/m2).

INTERVENTION

Eight-hour intravenous infusion of 0.4 pmol/kg/min PYY3-36 or rate-matched vehicle infusion.

MAIN OUTCOME MEASURES

Number of luteinizing hormone (LH) pulses, LH, follicle stimulating hormone (FSH), and testosterone levels.

RESULTS

The number of LH pulses (mean number of LH pulses/8 hours: PYY 4.4 ± 0.3 vs vehicle 4.4 ± 0.4, P > .99), LH area under the curve (AUC) (PYY 1503 ± 79 IU.min/L vs vehicle 1574 ± 86 IU.min/L, P = .36), FSH AUC (PYY 1158 ± 513 IU.min/L vs vehicle 1199 ± 476 IU.min/L, P = .49) and testosterone AUC (PYY 10 485 ± 684 IU.min/L vs vehicle 11 133 ± 803 IU.min/L, P = .24) were similar during PYY and vehicle infusions.

CONCLUSIONS

Acute intravenous infusion of 0.4 pmol/kg/min PYY does not affect the reproductive axis in healthy men.

Combined GLP-1, Oxyntomodulin, and Peptide YY Improves Body Weight and Glycemia in Obesity and Prediabetes/Type 2 Diabetes: A Randomized, Single-Blinded, Placebo-Controlled Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) augments postprandial secretion of glucagon-like peptide 1 (GLP-1), oxyntomodulin (OXM), and peptide YY (PYY). Subcutaneous infusion of these hormones ("GOP"), mimicking postprandial levels, reduces energy intake. Our objective was to study the effects of GOP on glycemia and body weight when given for 4 weeks to patients with diabetes and obesity.

RESEARCH DESIGN AND METHODS

In this single-blinded mechanistic study, obese patients with prediabetes/diabetes were randomized to GOP (n = 15) or saline (n = 11) infusion for 4 weeks. We also studied 21 patients who had undergone RYGB and 22 patients who followed a very low-calorie diet (VLCD) as unblinded comparators. Outcomes measured were 1) body weight, 2) fructosamine levels, 3) glucose and insulin during a mixed meal test (MMT), 4) energy expenditure (EE), 5) energy intake (EI), and 6) mean glucose and measures of glucose variability during continuous glucose monitoring.

RESULTS

GOP infusion was well tolerated over the 4-week period. There was a greater weight loss (P = 0.025) with GOP (mean change -4.4 [95% CI -5.3, -3.5] kg) versus saline (-2.5 [-4.1, -0.9] kg). GOP led to a greater improvement (P = 0.0026) in fructosamine (-44.1 [-62.7, -25.5] µmol/L) versus saline (-11.7 [-18.9, -4.5] µmol/L). Despite a smaller weight loss compared with RYGB and VLCD, GOP led to superior glucose tolerance after a mixed-meal stimulus and reduced glycemic variability compared with RYGB and VLCD.

CONCLUSIONS

GOP infusion improves glycemia and reduces body weight. It achieves superior glucose tolerance and reduced glucose variability compared with RYGB and VLCD. GOP is a viable alternative for the treatment of diabetes with favorable effects on body weight.

[18F] Fluciclatide PET as a biomarker of clinical response to combination therapy of pazopanib and paclitaxel in patients with platinum-resistant or platinum-refractory advanced ovarian cancer: Results of a phase Ib study

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Background: Angiogenesis has been shown to be a driver of platinum resistance in ovarian cancer. We assessed the effect of combination pazopanib and paclitaxel followed by maintenance pazopanib in patients with platinum resistant/refractory ovarian cancer. Integrins αvβ3 and αvβ5 are both up-regulated in tumour-associated vasculature. [18F]Fluciclatide is a novel PET tracer that has high affinity for integrins αvβ3/5, and was used to assess the anti-angiogenic effect of pazopanib. Methods: We conducted an open-label, phase Ib study in patients with platinum resistant/refractory ovarian cancer. Patients received 1 week of single agent pazopanib (800mg daily) followed by combination therapy with weekly paclitaxel 80mg/m2. Following completion of 18 weeks of therapy, patients continued with single agent pazopanib until disease progression. Dynamic [18F]Fluciclatide-PET imaging was conducted at baseline and after 1 week of pazopanib. Response (RECIST 1.1), toxicities and survival outcomes were recorded. Circulating markers of angiogenesis were assessed with therapy. Results: Fourteen patients were included in the intention-to-treat analysis. Complete and partial response was seen in 7 patients (54%). Median progression free survival (PFS) was 7.97 months, and overall survival (OS) was 18.5 months. A reduction in [18F]fluciclatide uptake was observed following 1 week of pazopanib, and the reduction in uptake was predictive of long PFS. Elevated baseline circulating angiopoietin and FGF were predictive of greater reduction in SUV60,mean following pazopanib. Kinetic modelling indicated a reduction in K1 and Ki following pazopanib indicating reduced radiotracer delivery and retention. Conclusions: Combination therapy followed by maintenance pazopanib is effective and tolerable in patients with platinum resistant/refractory ovarian cancer. We have shown that [18F]fluciclatide-PET uptake parameters alter with pazopanib therapy indicating an anti-angiogenic response. Clinical trial information: NCT01608009.

SUN-LB044 Effects of Glucagon-Like Peptide-1 (GLP-1) on the Hypothalamic-Pituitary-Gonadal Axis in Healthy Men

Introduction: Normal fertility requires the presence of adequate nutritional stores. The hormone glucagon-like peptide-1 (GLP-1) is a satiety hormone, which is released by intestinal L-cells during meal ingestion to act as a physiological signal of nutritional intake. GLP-1 reduces appetite and stimulates insulin release. Peripheral GLP-1 crosses the blood brain barrier and GLP-1 receptors (GLP-1R) are present in the arcuate nucleus of the hypothalamus (a neuroendocrine centre that regulates metabolism and reproduction). Both in vitro and in vivo animal studies have demonstrated stimulatory effects of GLP-1 on reproductive hormone release. Thus, GLP-1 acts as a signal of adequate energy intake and may act as a key mediator between metabolic and reproductive systems in animals. As GLP-1R agonists are widely used to treat obesity and diabetes, we sought to determine the effects of GLP-1 on the reproductive axis in humans. Methods: Using a blinded placebo-controlled protocol, 18 healthy men (age 24.7±1yr; mean BMI 22.1±0.4kg/m²) received an 8-hour infusion of 0.8pmol/kg/min of GLP-1 on one study visit and rate-matched vehicle infusion on a separate study visit, in random order. Blood samples were taken every ten minutes during infusions. Visual analogue scales (VAS: 0-10cm) for hunger and nausea were completed by the volunteers pre-, mid- and end-infusion. An ad libitum meal study was performed following the last VAS assessment, after which the infusion was stopped. Luteinizing hormone (LH) pulsatility was determined using blinded deconvolution analysis. Data is presented as mean±SEM. Results: GLP-1 infusion resulted in 14% lower food intake (GLP-1 937±87kcal vs vehicle 1094±87kcal, p=0.03) without increasing nausea (change from baseline VAS score: GLP-1 0.25±0.35cm vs vehicle 0.25±0.22cm, p=0.74). There was no difference in the number of LH pulses over 8hrs (GLP-1 4.7±0.3 vs vehicle 4.4±0.4, p=0.38), LH pulse mass (GLP-1 4.82±0.38IU/L vs vehicle 4.78±0.42IU/L, p=0.94), mean LH (GLP-1 2.86±0.2IU/L vs vehicle 2.75±0.2IU/L, p=0.50), LH AUC (GLP-1 1524±101IU.min/L vs vehicle 1484±88IU.min/L, p=0.70), FSH AUC (GLP-1 1216±112IU.min/L vs vehicle 1210±112IU.min/L, p=0.86) or testosterone AUC (GLP-1 11088±792nmol.min/L vs vehicle 10893±615nmol.min/L, p=0.77). Conclusions: Our results indicate that GLP-1 administration, at a biologically active dose (which reduces food intake), has neither a detrimental nor stimulatory effect on the reproductive axis. This provides important safety data for GLP-1 based therapeutic agents. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Type 2 diabetes remission 2 years post Roux-en-Y gastric bypass and sleeve gastrectomy: the role of the weight loss and comparison of DiaRem and DiaBetter scores

AIMS

The comparative efficacy of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy on Type 2 diabetes remission and the role of weight loss are unclear. The DiaRem diabetes remission prediction score uses HbA_1c , age and diabetes medications but not diabetes duration. The aim of this study was to compare the DiaRem with the DiaBetter score that includes diabetes duration, upon combined (complete plus partial) 2-year post-surgery diabetes remission in people following RYGB and sleeve gastrectomy, and to investigate the relationship between weight loss and diabetes remission.

METHODS

A retrospective single-centre cohort study of obese people with diabetes who underwent RYGB (107) or sleeve gastrectomy (103) and a validation cohort study (173) were undertaken. Diabetes remission, % weight loss, DiaRem, DiaBetter scores and areas under receiving operator characteristic (ROC) curves were calculated. The relationship between % weight loss and diabetes remission was investigated using logistic regression.

RESULTS

The proportion of people achieving diabetes remission was highest for those with the lowest DiaBetter and DiaRem scores. Areas under the ROC curves were comparable [DiaBetter: 0.867 (95%CI: 0.817-0.916); DiaRem: 0.865 (95%CI: 0.814-0.915), P=0.856]. Two-year % weight loss was higher post RYGB [26.6 (95%CI: 24.8-28.4)] vs post-sleeve gastrectomy [20.6 (95%CI: 18.3-22.8), P<0.001]. RYGB had 151% higher odds of diabetes remission [OR 2.51 (95%CI: 1.12-5.60), P=0.025]. This association became non-significant when adjusted for % weight loss.

CONCLUSION

DiaBetter and DiaRem scores predict diabetes remission following both procedures. Two-year % weight loss plays a key role in determining diabetes remission.

Roles of increased glycaemic variability, GLP-1 and glucagon in hypoglycaemia after Roux-en-Y gastric bypass

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment for diabetes and obesity. An increasingly recognized and highly disabling complication of RYGB is postprandial hypoglycaemia (PPH). The pathophysiology of PPH remains unclear with multiple mechanisms suggested including nesidioblastosis, altered insulin clearance and increased glucagon-like peptide-1 (GLP-1) secretion. Whilst many PPH patients respond to dietary modification, some have severely disabling symptoms. Multiple treatments are proposed, including dietary modification, GLP-1 antagonism, GLP-1 analogues and even surgical reversal, with none showing a more decided advantage over the others. A greater understanding of the pathophysiology of PPH could guide the development of new therapeutic strategies.

METHODS

We studied a cohort of PPH patients at the Imperial Weight Center. We performed continuous glucose monitoring to characterize their altered glycaemic variability. We also performed a mixed meal test (MMT) and measured gut hormone concentrations.

RESULTS

We found increased glycaemic variability in our cohort of PPH patients, specifically a higher mean amplitude glucose excursion (MAGE) score of 4.9. We observed significantly greater and earlier increases in insulin, GLP-1 and glucagon in patients who had hypoglycaemia in response to an MMT (MMT Hypo) relative to those that did not (MMT Non-Hypo). No significant differences in oxyntomodulin, GIP or peptide YY secretion were seen between these two groups.

CONCLUSION

An early peak in GLP-1 and glucagon may together trigger an exaggerated insulinotropic response to eating and consequent hypoglycaemia in patients with PPH.

Redefining the stress cortisol response to surgery

BACKGROUND

Cortisol levels rise with the physiological stress of surgery. Previous studies have used older, less-specific assays, have not differentiated by severity or only studied procedures of a defined type. The aim of this study was to examine this phenomenon in surgeries of varying severity using a widely used cortisol immunoassay.

METHODS

Euadrenal patients undergoing elective surgery were enrolled prospectively. Serum samples were taken at 8 am on surgical day, induction and 1 hour, 2 hour, 4 hour and 8 hour after. Subsequent samples were taken daily at 8 am until postoperative day 5 or hospital discharge. Total cortisol was measured using an Abbott Architect immunoassay, and cortisol-binding globulin (CBG) using a radioimmunoassay. Surgical severity was classified by POSSUM operative severity score.

RESULTS

Ninety-three patients underwent surgery: Major/Major+ (n = 37), Moderate (n = 33) and Minor (n = 23). Peak cortisol positively correlated to severity: Major/Major+ median 680 [range 375-1452], Moderate 581 [270-1009] and Minor 574 [272-1066] nmol/L (Kruskal-Wallis test, P = .0031). CBG fell by 23%; the magnitude of the drop positively correlated to severity.

CONCLUSIONS

The range in baseline and peak cortisol response to surgery is wide, and peak cortisol levels are lower than previously appreciated. Improvements in surgery, anaesthetic techniques and cortisol assays might explain our observed lower peak cortisols. The criteria for the dynamic testing of cortisol response may need to be reduced to take account of these factors. Our data also support a lower-dose, stratified approach to dosing of steroid replacement in hypoadrenal patients, to minimize the deleterious effects of over-replacement.

The Effect of a Subcutaneous Infusion of GLP-1, OXM, and PYY on Energy Intake and Expenditure in Obese Volunteers

BACKGROUND

Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment of obesity, although limited by availability and operative risk. The gut hormones Glucagon-like peptide-1 (GLP-1), Peptide YY (PYY), and Oxyntomodulin (OXM) are elevated postprandially after RYGB, which has been postulated to contribute to its metabolic benefits.

OBJECTIVE

We hypothesized that infusion of the three gut hormones to achieve levels similar to those encountered postprandially in RYGB patients might be effective in suppressing appetite. The aim of this study was to investigate the effect of a continuous infusion of GLP-1, OXM, and PYY (GOP) on energy intake and expenditure in obese volunteers.

METHODS

Obese volunteers were randomized to receive an infusion of GOP or placebo in a single-blinded, randomized, placebo-controlled crossover study for 10.5 hours a day. This was delivered subcutaneously using a pump device, allowing volunteers to remain ambulatory. Ad libitum food intake studies were performed during the infusion, and energy expenditure was measured using a ventilated hood calorimeter.

RESULTS

Postprandial levels of GLP-1, OXM, and PYY seen post RYGB were successfully matched using 4 pmol/kg/min, 4 pmol/kg/min, and 0.4 pmol/kg/min, respectively. This dose led to a mean reduction of 32% in food intake. No significant effects on resting energy expenditure were observed.

CONCLUSION

This is, to our knowledge, the first time that an acute continuous subcutaneous infusion of GOP, replicating the postprandial levels observed after RYGB, is shown to be safe and effective in reducing food intake. This data suggests that triple hormone therapy might be a useful tool against obesity.

Coinfusion of low-dose GLP-1 and glucagon in man results in a reduction in food intake

Obesity is a growing epidemic, and current medical therapies have proven inadequate. Endogenous satiety hormones provide an attractive target for the development of drugs that aim to cause effective weight loss with minimal side effects. Both glucagon and GLP-1 reduce appetite and cause weight loss. Additionally, glucagon increases energy expenditure. We hypothesized that the combination of both peptides, administered at doses that are individually subanorectic, would reduce appetite, while GLP-1 would protect against the hyperglycemic effect of glucagon. In this double-blind crossover study, subanorectic doses of each peptide alone, both peptides in combination, or placebo was infused into 13 human volunteers for 120 min. An ad libitum meal was provided after 90 min, and calorie intake determined. Resting energy expenditure was measured by indirect calorimetry at baseline and during infusion. Glucagon or GLP-1, given individually at subanorectic doses, did not significantly reduce food intake. Coinfusion at the same doses led to a significant reduction in food intake of 13%. Furthermore, the addition of GLP-1 protected against glucagon-induced hyperglycemia, and an increase in energy expenditure of 53 kcal/day was seen on coinfusion. These observations support the concept of GLP-1 and glucagon dual agonism as a possible treatment for obesity and diabetes.

Psychological characteristics, eating behavior, and quality of life assessment of obese patients undergoing weight loss interventions

BACKGROUND AND AIMS

Bariatric surgery is the most effective treatment for obesity. However, not all patients have similar weight loss following surgery and many researchers have attributed this to different pre-operative psychological, eating behavior, or quality-of-life factors. The aim of this study was to determine whether there are any differences in these factors between patients electing to have bariatric surgery compared to less invasive non-surgical weight loss treatments, between patients choosing a particular bariatric surgery procedure, and to identify whether these factors predict weight loss after bariatric surgery.

MATERIAL AND METHODS

This was a prospective study of 90 patients undergoing gastric bypass, vertical sleeve gastrectomy, or adjustable gastric banding and 36 patients undergoing pharmacotherapy or lifestyle interventions. All patients completed seven multi-factorial psychological, eating behavior, and quality-of-life questionnaires prior to choosing their weight loss treatment. Questionnaire scores, baseline body mass index, and percent weight loss at 1 year after surgical interventions were recorded.

RESULTS AND CONCLUSIONS

Surgical patients were younger, had a higher body mass index, and obesity had a higher impact on their quality of life than on non-surgical patients, but they did not differ in the majority of eating behavior and psychological parameters studied. Patients opting for adjustable gastric banding surgery were more anxious, depressed, and had more problems with energy levels than those choosing vertical sleeve gastrectomy, and more work problems compared to those undergoing gastric bypass. Weight loss after bariatric surgery was predicted by pre-operative scores of dietary restraint, disinhibition, and pre-surgery energy levels. The results of this study generate a number of hypotheses that can be explored in future studies and accelerate the development of personalized weight loss treatments.

Modifying an immunogenic epitope on a therapeutic protein: a step towards an improved system for antibody-directed enzyme prodrug therapy (ADEPT)

Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.