Metabolic Balance Studies Research Articles

Efficacy and safety of apraglutide in short bowel syndrome with intestinal failure and colon–in–continuity: A multicenter, open-label, metabolic balance study

BackgroundApraglutide is a novel long-acting GLP-2 analog in development for short bowel syndrome with intestinal failure (SBS-IF). This multicenter, open-label, phase 2 study in SBS-IF and colon-in-continuity (CiC) investigates the safety and efficacy of apraglutide. MethodsThis was a 52-week phase 2 metabolic balance study (MBS) in 9 adult patients with SBS-IF-CiC receiving once-weekly subcutaneous apraglutide injections. Safety was the primary endpoint. Secondary endpoints included changes in absorption parameters (MBS at baseline, after 4 weeks with stable parenteral support (PS), and 48 weeks), PS needs (48-week PS adjustment period based on monthly 48-hour fluid balances) and intestinal morphology and motility (static and cine MRI at baseline and 4, 24 and 48 weeks). ResultsPS volume decreased by -4702mL/week (-52%; p<0.001) at week 52. Seven patients (78%) achieved ≥1 day off PS at week 52. At 4 weeks, fecal output was reduced by 253 g/day (p=0.013). At 48 weeks, increases in wet weight absorption by 316 g/day (p=0.039), energy absorption by 1134 kJ/day (p=0.041) and carbohydrate absorption by 56.1 g/day (p= 0.024) were observed. Moreover, small bowel length increased from 29.7 to 40.7 cm (p=0.012), duodenal wall thickness increased by 0.8 mm (p=0.02) and motility in the proximal colon was reduced (p=0.031). A total of 127 adverse events was reported, which were mostly mild to moderate. ConclusionApraglutide had an acceptable safety profile and was associated with significant reductions in PS needs and days off PS, improvements in intestinal absorption, and structural and functional intestinal changes in patients with SBS-IF-CiC.ClinicalTrials.gov, Number NCT04964986

Assessing Human Iron Kinetics Using Stable Iron Isotopic Techniques.

Stable iron isotope techniques are critical for developing strategies to combat iron deficiency anemia, a leading cause of global disability. There are four primary stable iron isotope methods to assess ferrokinetics in humans. (i) The fecal recovery method applies the principles of a metabolic balance study but offers enhanced accuracy because the amount of iron isotope present in feces can be directly traced back to the labeled dose, distinguishing it from endogenous iron lost in stool from shed intestinal cells. (ii) In the plasma isotope appearance method, plasma samples are collected for several hours after oral dosing to evaluate the rate, quantity, and pattern of iron absorption. Key metrics include the time of peak isotope concentration and the area under the curve. (iii) The erythrocyte iron incorporation method measures iron bioavailability (absorption and erythrocyte iron utilization) from a whole blood sample collected 2 weeks after oral dosing. Simultaneous administration of oral and intravenous tracers allows for separate measurements of iron absorption and iron utilization. These threemethods determine iron absorption by measuring tracer concentrations in feces, serum, or erythrocytes after administration of a tracer. In contrast, (iv) in iron isotope dilution, an innovative new approach, iron of natural composition acts as the tracer, diluting an ad hoc modified isotopic signature obtained via prior isotope administration and equilibration with body iron. This technique enables highly accurate long-term studies of iron absorption, loss, and gain. This review discusses the application of these kinetic methods and their potential to address important questions in hematology andiron biology.

Sex-dependent polymorphism in urinary output is reversed upon deletion of exchange protein directly activated by cAMP (Epac)

It is well-described that there are notable sex-dependent differences in urinary production with females having a smaller volume and greater urinary concentrating ability. Apart from contribution of the androgenic inputs, the underlying signaling intermediates remain largely unexplored. We previously showed that exchange protein directly activated by cAMP (Epac) is a critical regulator of water-solute transport in the proximal tubule and collecting duct. Deletion of either Epac1 or Epac2 isoforms increases urinary output and Na+ excretion. Here, we used metabolic cage balance studies to test whether Epac signaling mediates sex-dependent differences in urinary production. We found that concomitant deletion of Epac1&amp;2 moderately increases 24h urinary volume by 38% (from 1.82+/-0.13 to 2.52+/-0.21 ml) in males, but drastically augment urinary production in females by 320% (from 1.39+/-0.10 to 4.45+/-0.37 ml). This was associated with only a mild though significant reduction in urinary osmolarity in males by 35%, whereas urine osmolarity was markedly decreased from 2511+/-5 to 977+/-60 mOsm in females. Consistently, plasma osmolarity was not different in EpacWT versus Epac1&amp;2−/− males, but became significantly more hypertonic in Epac1&amp;2−/− females. We further determine the functional consequences of impaired Epac cascade on fluid reabsorption in the proximal tubule and collecting duct in males and females. Deletion of Epac1 and Epac2 decreases NHE-3 expression in the proximal tubule in an additive manner. In addition, Na+/H+-dependent recovery after acidification was drastically reduced in freshly isolated split-opened proximal tubules from Epac1&amp;2−/− mice when compared to EpacWT. Interestingly, the reduction of NHE-3 expression was more pronounced in Epac1&amp;2−/− females (by 89%) than in males (by 59%). Immunofluorescence confocal images revealed much more diffuse intracellular distribution of AQP2 water channel in Epac1&amp;2−/− females when compared to males. Furthermore, osmotically-driven water influx was reduced in principal cells within split-opened collecting ducts of Epac1&amp;2−/− females but not males, when compared to respective EpacWT. In summary, our results reveal a substantially greater role of Epac signaling in renal water handling in females than in males. Interestingly, Epac1&amp;2 deletion leads to a reversed pattern of sexual dimorphism in urinary production with females excreting larger volumes of hypotonic urine than males. This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, in patients with short bowel syndrome and colon in continuity: an open-label pilot study

ObjectivePatients with short bowel syndrome (SBS) and colon in continuity have better adaptation potential compared with patients with jejunostomy. Adaptation may involve enhanced postprandial secretion of the enteroendocrine hormones glucagon-like...

A high-protein total diet replacement increases energy expenditure and leads to negative fat balance in healthy, normal-weight adults

ABSTRACTBackgroundHigh-protein diets and total diet replacements are becoming increasingly popular for weight loss; however, further research is needed to elucidate their impact on the mechanisms involved in weight regulation.ObjectiveThe aim of this inpatient metabolic balance study was to compare the impact of a high-protein total diet replacement (HP-TDR) versus a control diet (CON) on select components of energy metabolism in healthy adults of both sexes.MethodsThe acute intervention was a randomized, controlled, crossover design with participants allocated to 2 isocaloric arms: 1) HP-TDR: 35% carbohydrate, 40% protein, and 25% fat achieved through a nutritional supplement; 2) CON: 55% carbohydrate, 15% protein, and 30% fat. Participants received the prescribed diets for 32 h while inside a whole-body calorimetry unit (WBCU). The first dietary intervention randomly offered in the WBCU was designed to maintain energy balance and the second matched what was offered during the first stay. Energy expenditure, macronutrient oxidation rates and balances, and metabolic blood markers were assessed. Body composition was measured at baseline using DXA.ResultsForty-three healthy, normal-weight adults (19 females and 24 males) were included. Compared with the CON diet, the HP-TDR produced higher total energy expenditure [(EE) 81 ± 82 kcal/d, P <0.001], protein and fat oxidation rates (38 ± 34 g/d, P <0.001; 8 ± 20 g/d, P = 0.013, respectively), and a lower carbohydrate oxidation rate (–38 ± 43 g/d, P <0.001). Moreover, a HP-TDR led to decreased energy (–112 ± 85 kcal/d; P <0.001), fat (–22 ± 20 g/d; P <0.001), and carbohydrate balances (–69 ± 44 g/d; P <0.001), and increased protein balance (90 ± 32 g/d; P <0.001).ConclusionsOur primary findings were that a HP-TDR led to higher total EE, increased fat oxidation, and negative fat balance. These results suggest that a HP-TDR may promote fat loss compared with a conventional isocaloric diet. These trials were registered at clinicaltrials.gov as NCT02811276 and NCT03565510.

Abstract P020: LOSS OF SOLUBLE (PRO)RENIN RECEPTOR ATTENUATES DOCA-SALT HYPERTENSION

Cleavage of the extra-cellular domain of the (pro)renin receptor (PRR) yields a soluble fragment (sPRR), which maybe involved in mediating hypertension. We recently developed a novel mouse model with mutation in the cleavage site of the PRR using CRISPR/Cas9 such that sPRR is not generated and showed that absence of sPRR attenuated angiotensin-II induced hypertension and kidney damage. In this study, we examined if sPRR alters blood pressure (BP) in angiotensin-II independent hypertension using deoxycorticosterone acetate (DOCA)-salt treatment. Mutant sPRR mice and littermate controls were treated with DOCA (50 mg/kg) and high Na + diet for 3 weeks. BP was monitored by radio-telemetry and metabolic balance studies performed at the end of the study (Day 17-18). Compared to controls, male mutant sPRR mice had markedly lower plasma sPRR levels (control: 21.5 ± 2.5 vs mutant 0.2 ± 0.03 ng/ml) and baseline BP (systolic control: 122 ± 3 vs mutant 114 ± 3; diastolic control: 94 ±5 vs mutant 82 ± 3 mm Hg). BP remained low in mutant sPRR mice relative to controls following 12 days of DOCA-salt treatment (systolic control: 141 ± 2 vs mutant 132 ± 5; diastolic control: 110 ± 4 vs mutant 95 ± 5 mm Hg). Mutant sPRR mice had lower body weight but similar food intake and urinary albumin excretion compared to controls (Table 1). Mutant sPRR mice had lower urine volume, water intake and urinary K + but not Na + excretion. No differences in renal histology were noted between control and mutant sPRR mice. Loss of sPRR attenuates DOCA-salt mediated hypertension. The mechanisms by which sPRR might regulate BP and water/Na + homeostasis in DOCA-salt hypertension are currently being investigated.

Use of Calcium Isotopic Tracers To Determine Factors That Perturb Calcium Metabolism.

Calcium plays an important role in maintaining bone health. Ensuring adequate calcium intake throughout life is essential for reaching greater peak bone mass in young adulthood and lowering osteoporotic fracture risk when aging. Calcium homeostasis involves a complex interaction between three organ systems: intestine, kidney, and bone. Metabolic balance plus kinetic studies using calcium isotopic tracers can estimate calcium metabolism parameters and pinpoint how organs and processes are perturbed by internal and external modifiers. Both modifiable factors (e.g., vitamin D supplementations and dietary bioactives) and non-modifiable factors (e.g., age, sex, and race) influence calcium utilization. Current evidence suggests that prebiotic fibers may offer an alternative approach to enhance calcium absorption through altering gut microbiota to ultimately improve bone health.

Examining the effects of a high-protein total diet replacement on energy metabolism, metabolic blood markers, and appetite sensations in healthy adults: protocol for two complementary, randomized, controlled, crossover trials

BackgroundHigh-protein diets and total diet replacements are becoming increasingly popular for weight regulation; however, further research is needed to elucidate their impact on the physiology of body weight regulation. The aim of this inpatient metabolic balance study is to compare the impact of a high-protein total diet replacement versus a control diet (North American) on energy expenditure, macronutrient oxidation rates and balances, metabolic blood markers and appetite sensations in healthy adults.MethodsTwo randomized, controlled, cross-over clinical trials conducted separately in men and women will be conducted. In each trial, participants will be allocated to two isocaloric arms: a) Control diet: 55% carbohydrate, 15% protein, and 30% fat; b) High-protein total diet replacement: 35% of carbohydrate, 40% protein, and 25% fat. They will receive the prescribed diets for 32 h while inside the whole-body calorimetry unit. Diets will be designed to ensure participants are in energy balance. The following physiological changes will be compared between groups: energy expenditure, macronutrient oxidation rates and balances, metabolic blood markers, and appetite sensations. Body composition will be assessed at baseline using dual-energy X-ray absorptiometry.DiscussionThis will be the first inpatient metabolic balance study examining the impact of a high-protein total diet replacement on energy metabolism, metabolic blood markers and appetite sensations in healthy young adults (of both sexes) using a whole-body calorimetry unit. Results of this clinical trial can ultimately be used to develop strategies to optimize high-protein diet interventions and weight management.Trial registrationClinicalTrials.gov Identifiers: NCT02811276 (registered on 16 June 2016) and NCT03565510 (registered on 11 June 2018).Protocol versionNCT02811276: version 10 (2 March 2018); NCT03565510: version 3 (28 September 2018).

Repeated Metabolic Balance Studies in Patients With Short Bowel Syndrome.

Weaning from parenteral support is considered indirect evidence of intestinal adaptation in patients with short bowel syndrome (SBS), but direct evidence is lacking. The objective of this study was to examine if intestinal adaptation could be demonstrated as increase in intestinal absorption of energy and wet weight over time measured by repeated metabolic balance studies (MBSs) and to examine whether adaptation was determined by the anatomy of the remnant bowel. We retrospectively analyzed data from 48 repeated MBSs performed in 13 adult patients with SBS. Results were presented graphically and interpreted. The interpatient and intrapatient heterogeneity was compared based on anatomy of the remnant bowel. The number of repeated MBSs ranged from 2 to 7, and time between last intestinal resection and MBS from 5 months to 18.1years. In 6 patients, the first MBS was performed within 2years after last resection, but only 1 patient had repeated MBSs within this period. Nine patients had an end jejunoileostomy, and 4 patients had a jejuno-colonic or ileo-colonic anastomosis. None of the patients had jejunoileal anastomosis with a preserved ileocecal valve. Interpatient and intrapatient heterogeneity of wet weight and energy absorption was larger in patients without colon in continuity. The wet weight and energy absorption data showed no tendency toward intestinal adaptation in any anatomical group. We observed no signs of late-phase intestinal adaptation in this selected group of patients with SBS. Future prospective MBSs are needed to understand the time course and magnitude of intestinal adaptation.

Glepaglutide, a novel long-acting glucagon-like peptide-2 analogue, for patients with short bowel syndrome: a randomised phase 2 trial

Patients with short bowel syndrome might have impaired postprandial endogenous glucagon-like peptide-2 (GLP-2) secretion, which is required for optimal intestinal adaptation. We aimed to assess the therapeutic potential of glepaglutide, a novel long-acting GLP-2 analogue, for reducing faecal output and increasing intestinal absorption in patients with short bowel syndrome. In this single-centre, double-blind, crossover, randomised phase 2 trial, adults (aged ≥18 to ≤90 years) with short bowel syndrome and with a faecal wet weight output of 1500 g/day or more were randomly assigned to receive one of six dose sequences of glepaglutide (10 mg, 1 mg; 10 mg, 0·1 mg; 1 mg, 10 mg; 1 mg, 0·1 mg; 0·1 mg, 10 mg; or 0·1 mg, 1 mg). Patients received daily subcutaneous injections of the first assigned dose of glepaglutide for 3 weeks, followed by a washout period of 4-8 weeks, and then the second dose of glepaglutide for 3 weeks. An unmasked statistician generated the randomisation list, and the trial investigator enrolled patients and assigned them their patient numbers. Trial investigators, patients, and other care providers were masked throughout the trial. The primary endpoint was the absolute change from baseline in faecal wet weight output, measured separately over the two treatment periods. Metabolic balance studies were done before and after each treatment period to assess the primary endpoint. Per-protocol analysis was used to assess the efficacy. Safety analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCT02690025, and has completed. Of the 22 patients screened between Feb 5, 2016, and Jan 25, 2017, 18 patients were randomly assigned and treated with glepaglutide; 16 patients completed the trial. Treatment with 1 mg and 10 mg glepaglutide changed the adjusted mean faecal output by -592 g/day (95% CI -913 to -272; p=0·002) and -833 g/day (-1152 to -515; p=0·0002) from baseline, respectively. No changes were observed with 0·1 mg glepaglutide. Of the 18 patients who were randomly assigned to treatment, common treatment-related adverse events were stoma complications (13 [72%] patients), injection site reactions (11 [61%]), peripheral oedema (ten [56%]), nausea and abdominal pain (eight [44%] each), polyuria and fatigue (six [33%] each), abdominal distention, vomiting, and dizziness (five [28%] each); and cough and decreased appetite (four [22%] each). Related or possibly related serious adverse events were reported in two patients in the 0·1 mg dose group and two patients in the 10 mg dose group. These events included abdominal pain, stoma obstruction, catheter-related sepsis, and infection of unknown origin. No patients died during the trial. Glepaglutide was well tolerated, and was associated with improved intestinal absorption in patients with short bowel syndrome with 1 mg and 10 mg glepaglutide, but not with 0·1 mg glepaglutide. Larger phase 3 clinical trials of longer durations have been initiated to fully assess the safety and efficacy of glepaglutide. Zealand Pharma.

Abstract P246: Increased Urinary Prorenin and sPRR Excretion in Early Type 1 Diabetes

Activation of the intra-renal, rather than systemic renin angiotensin system (RAS) has been suggested to play a role in the development of diabetic kidney disease. In this study, we examined plasma and urinary prorenin/renin levels and urinary soluble prorenin receptor (sPRR) levels in a murine model of Type 1 diabetes. Male C57BL/6 mice were injected with streptozotocin (STZ) 50mg/kg at 3 months of age and metabolic balance studies conducted at 6 and 10 weeks post-injection. STZ injected mice developed hyperglycemia within 4 weeks of injection (STZ: 335 ± 35 vs control: 145 ± 22 mg/dL) and remained hyperglycemic at 10 weeks. At 10 weeks post-injection, STZ injected mice had significant polyuria (STZ: 20.9 ± 5.9 vs controls 1.8 ± 0.4 ml/day), increased water intake (STZ: 26.2 ± 5.9 vs controls: 6.2 ± 0.9 ml/day) and lower body weight (STZ: 28.3 ± 1.3 vs controls: 23.6 ± 1.4 grams) despite similar food intake. Compared to controls, urinary angiotensinogen, total prorenin/renin and sPRR levels were increased in STZ injected mice; these increases were proportionally greater than the trend in increased urinary microalbumin excretion (Table 1). In particular, urinary sPRR excretion was markedly increased in STZ injected mice compared to controls. In a separate experiment, 10 week old male Akita mice bearing a mutated Ins2 gene, demonstrated a 4.8 fold increase in renal medullary renin mRNA expression and a 1.5-fold increase in renal medullary PRR expression. Taken together, these results demonstrate early activation of the intra-renal RAS in Type 1 diabetes. These changes occur independent of the systemic RAS.

THE EFFECT OF DIETARY OILS AND HYDROLYZED COCONUT OIL ON MINERALS ABSORPTION IN RATS.

Objective: The objective of this study was to investigate the effect of coconut oil (virgin coconut oil; VCO), corn oil, palm oil, and hydrolyzed VCO (HVCO) on minerals (calcium and magnesium) absorption in rats.Methods: The oils used were corn oil, palm oil, VCO, and HVCO. VCO hydrolysis was done using lipase from Rhizomucor miehei (active on sn-1,3 position). The effect of oils and HVCO on minerals absorption was carried out on 25 male rats, weighing approximately 150–200 g. Rats were housed in air-conditioned room at 22–25°C, under 12-light/dark cycle, fed on basal diet and tap water ad libitum. After 1-week acclimatization, rats were given oils and HVCO for 21 days. The effect of oils on the minerals absorption were determined over the 4-day metabolic balance study. Mineral concentrations in diet, feces, urine, and serum were measured using atomic absorption spectrometry. Minerals absorption are expressed as apparent minerals absorption, apparent minerals absorption rate, and apparent minerals balance.Results: Calcium absorption in rats given with VCO, corn oil, palm oil, and HVCO is 47.09%, 45.46%, 44.48%, and 49.33%, respectively, whereas, magnesium absorption in rats given with VCO, corn oil, palm oil, and HVCO is 34.87%, 32.08%, 29.39%, and 37.11%, respectively. The results of this study show that minerals absorption in rats given with dietary oils is significantly lower than the control group (51.79% for calcium and 42.34% for magnesium). Mineral absorption in rats given with HVCO results in the highest rate of all rats given with the other oils tested.Conclusion: Corn oil and palm oil, which belong to the long chain triglycerides oil, lower calcium, and magnesium absorption more significantly than VCO as a medium chain triglyceride oil does. HVCO results in significantly higher calcium and magnesium absorption compared to non-HVCO.

THE EFFECT OF DIETARY OILS AND HYDROLYZED COCONUT OIL ON MINERALS ABSORPTION IN RATS.

Objective: The objective of this study was to investigate the effect of coconut oil (virgin coconut oil; VCO), corn oil, palm oil, and hydrolyzed VCO (HVCO) on minerals (calcium and magnesium) absorption in rats.Methods: The oils used were corn oil, palm oil, VCO, and HVCO. VCO hydrolysis was done using lipase from Rhizomucor miehei (active on sn-1,3 position). The effect of oils and HVCO on minerals absorption was carried out on 25 male rats, weighing approximately 150–200 g. Rats were housed in air-conditioned room at 22–25°C, under 12-light/dark cycle, fed on basal diet and tap water ad libitum. After 1-week acclimatization, rats were given oils and HVCO for 21 days. The effect of oils on the minerals absorption were determined over the 4-day metabolic balance study. Mineral concentrations in diet, feces, urine, and serum were measured using atomic absorption spectrometry. Minerals absorption are expressed as apparent minerals absorption, apparent minerals absorption rate, and apparent minerals balance.Results: Calcium absorption in rats given with VCO, corn oil, palm oil, and HVCO is 47.09%, 45.46%, 44.48%, and 49.33%, respectively, whereas, magnesium absorption in rats given with VCO, corn oil, palm oil, and HVCO is 34.87%, 32.08%, 29.39%, and 37.11%, respectively. The results of this study show that minerals absorption in rats given with dietary oils is significantly lower than the control group (51.79% for calcium and 42.34% for magnesium). Mineral absorption in rats given with HVCO results in the highest rate of all rats given with the other oils tested.Conclusion: Corn oil and palm oil, which belong to the long chain triglycerides oil, lower calcium, and magnesium absorption more significantly than VCO as a medium chain triglyceride oil does. HVCO results in significantly higher calcium and magnesium absorption compared to non-HVCO.

Fasting and Postprandial Plasma Citrulline and the Correlation to Intestinal Function Evaluated by 72-Hour Metabolic Balance Studies in Short Bowel Jejunostomy Patients With Intestinal Failure.

Fasting plasma citrulline (p-citrulline) is a marker of functional enterocyte mass. However, the optimal timing of measurement in relation to meals has yet to be clarified. Furthermore, p-citrulline has been proposed to be a surrogate marker for small bowel length and intestinal absorption parameters in short bowel syndrome patients with intestinal failure (SBS-IF). Eight patients with SBS-IF and 8 healthy controls (HCs) were given a standardized mixed test meal, and p-citrulline was measured 15 minutes before and 60, 120, and 180 minutes after completion of the meal. The patients with SBS-IF had their intestinal absorption of wet weight, energy, macronutrients, and electrolytes measured in relation to 72-hour metabolic balance studies. We investigated the possible correlations between p-citrulline and short bowel length, absorptive parameters, and the dependence on parenteral support (PS). In the patients with SBS-IF, we found a 12% (P = .041) reduction in postprandial citrulline levels after 180 minutes. In the HCs, there was a 13% postprandial reduction at 60 minutes (P = .018). No significant correlations between fasting p-citrulline and bowel length, bowel absorptive function, or the dependence on PS were found. Even when excluding 2 patients in whom the intestinal absorption was adjacent to the intestinal insufficiency borderlines, these correlations were not significant. Based on findings in this small study, the optimal timing of p-citrulline measurement is on fasting samples. However, p-citrulline seems insufficiently discriminative to serve as a valid biomarker of bowel length, bowel absorptive function, or dependence on PS in patients with SBS-IF.

Effect of Liraglutide Treatment on Jejunostomy Output in Patients With Short Bowel Syndrome: An Open-Label Pilot Study.

An impaired hormonal "ileo-colonic brake" may contribute to rapid gastric emptying, gastric hypersecretion, high ostomy losses, and the need for parenteral support in end-jejunostomy short bowel syndrome (SBS) patients with intestinal failure (IF). Liraglutide, a glucagon-like peptide 1 receptor agonist, may reduce gastric hypersecretion and dampen gastric emptying, thereby improving conditions for intestinal absorption. In an 8-week, open-label pilot study, liraglutide was given subcutaneously once daily to 8 end-jejunostomy patients, aged 63.4 ± 10.9 years (mean ± SD) and with small bowel lengths of 110 ± 66 cm. The 72-hour metabolic balance studies were performed before and at the end of treatment. Food intake was unrestricted. Oral fluid intake and parenteral support volume were kept constant. The primary end point was change in the ostomy wet weight output. Liraglutide reduced ostomy wet weight output by 474 ± 563 g/d from 3249 ± 1352 to 2775 ± 1187 g/d (P = .049, Student t test). Intestinal wet weight absorption tended to increase by 464 ± 557 g/d (P = .05), as did urine production by 765 ± 759 g/d (P = .02). Intestinal energy absorption improved by 902 ± 882 kJ/d (P = .02). Liraglutide reduced ostomy wet weight output in end-jejunostomy patients with SBS-IF and increased their intestinal wet weight and energy absorption. If larger, randomized, placebo-controlled studies confirm these effects, it adds to the hypothesis that many ileo-colonic brake hormones in conjunction may be involved in the process of intestinal adaptation. By identification of key hormones and addressing their potential synergistic effects, better treatments may be provided to patients with SBS-IF. This trial was registered at clinicaltrialsregister.eu as 2013-005499-16.

The use of metabolic balance studies in the objective discrimination between intestinal insufficiency and intestinal failure

Background: In research settings that use metabolic balance studies (MBSs) of stable adult patients with short bowel syndrome, intestinal failure (IF) and dependence on parenteral support (PS) have been defined objectively as energy absorption <84% of calculated basal metabolic rate (BMR), wet weight (WW) absorption <23 g · kg body weight-1 · d-1, or both. Objective: This study aimed to explore and validate these borderlines in the clinical setting.Design: Intestinal absorption was measured from April 2003 to March 2015 in 175 consecutive patients with intestinal insufficiency (INS) in 96-h MBSs. They had not received PS 3 mo before referral.Results: To avoid the need for PS, the minimum absorptive requirements were energy absorption of ≥81% of BMR and WW absorption of ≥21 g · kg body weight-1 · d-1, which were equivalent to findings in research settings (differences of 3.6% and 8.7%; P = 0.65 and 0.60, respectively). Oral failure defined as energy intake <130% of calculated BMR or WW intake <40 g · kg body weight-1 · d-1 was seen in 71% and 82% of the 10% of patients with the lowest energy absorption and WW absorption, respectively.Conclusions: In clinical settings, the borderlines between INS and IF were not significantly different from those in research settings, even in an unselected patient population in which oral failure was also a predominant cause of nutritional dyshomeostasis. MBSs may be recommended to identify the individual patient in the spectrum from INS to IF, to objectivize the cause of nutritional dyshomeostasis (oral failure, malabsorption, or both), and to quantify the effects of treatment.

Robert P Heaney, MD: 1927–2016

Robert P Heaney Dr. Robert P. Heaney's six decades of research investigating bone physiology and biology had a profound impact in the field of osteoporosis. His early work at Creighton included the Creighton University “Nun” Study. Many people in the field recognize this study when it is mentioned. This project was originally designed as a 20-year project. Roman Catholic nuns with mother houses in the Omaha, NE, USA, area were invited to attend an 8-day inpatient metabolic balance study at 5-year intervals. Each admission was preceded by a 7-day diary recording all dietary intakes. The daily food provided to each inpatient study participant was matched for calcium, phosphorus, protein, fat, and carbohydrate to the intake recorded in the diaries. Dr. Heaney characterized plasma calcium kinetics using radio-calcium isotopes, which described the interface between the calcium in the skeleton and that in the circulation. He also measured calcium absorption efficiency and recorded obligate losses of calcium in the urine and stool. All of this focused on calcium and skeletal physiology, and pathogenesis of osteoporosis. This project ultimately culminated after 41 years with each subject studied at 5-year intervals. The study sample of 161 nuns who entered the study in 1967 decreased to 131 at the end of the study, ie, only 30 dropouts over this 41-year study, some of whom were deceased. This study documented the importance of calcium nutrition and the calcium loss at the time of menopause, and set the standard for the US recommendations for calcium intake. Dr. Heaney's research contributions pertained not only to bone and osteoporosis but also to other illnesses, such as end-stage renal disease and insulin resistance, in the study of vitamin D. He applied his skills in biologic kinetics to characterize the appearance and disappearance of calciferol and its various metabolites in the serum of humans. His research in vitamin D nutrition and its physiology has had an enormous impact on the understanding of vitamin D physiology. Dr. Heaney always stressed that a research project is not complete until the findings are disseminated. He took that responsibility seriously and was a prolific writer and a frequent speaker at scientific, corporate, and community meetings. He authored 866 scientific articles including abstracts, reviews and other scientific papers. He participated actively in policy making in groups such as the Office of Technology Assessment, US Congress, Scientific Advisory Panel on Osteoporosis and the Panel on Calcium and Related Nutrients, Food & Nutrition Board, National Academy of Science (NAS). His achievements were widely recognized and his awards include the Creighton University Lifetime Achievement Research Award, the Frederick C Bartter Award from the American Society for Bone and Mineral Research, the Kappa Delta award from the American College of Orthopedic Surgeons, the E.V. McCollum Award of the American Society for Clinical Nutrition, and the Institute CANDIA Scientific Prize from France. He was recognized by the National Osteoporosis Foundation as a “Legend of Osteoporosis.” Perhaps most importantly, he focused widespread attention on the importance of osteoporosis. In recognition of this, he was presented a lifetime achievement award in the US House of Representatives on November 10, 2015. Dr. Heaney has mentored a large number of people including the authors of this memorial. He was an icon in the fields of osteoporosis, bone physiology, bone diseases in general, and vitamin D. His mentorship has been inspirational for our students, residents, and fellows at Creighton University as well as similar trainees in other institutions. He has been an enthusiastic, passionate teacher of medicine and bone pathology and physiology. Dr. Heaney had another dimension known mostly inside Creighton. He has been very active in Creighton University's spiritual community. He was well known for his passion for the scripture and his contributions to “Daily Reflections” on the Creighton website. His spiritual writings have been a source of great inspiration for persons at Creighton University and beyond. He also wrote for a monthly Catholic magazine America and for the Creighton Magazine. Dr. Heaney and his late wife, Barbara, raised seven children, and, at his death, his descendants include 14 grandchildren, and three great grandchildren. They all were a source of great pride and much enjoyment for him. Dr. Heaney will be remembered as a healer, a thinker, and a man of grace and generosity. We are all greatly saddened by his loss. Robert R Recker, MD Osteoporosis Research Center, Creighton University, Omaha, NE, USA Joan M Lappe, PhD Osteoporosis Research Center, Creighton University, Omaha, NE, USA

Impact of Calcium Intake Levels on Urinary and Fecal Losses of Sodium, Potassium and Magnesium

Understanding of mineral interactions remains incomplete. Minerals such as sodium, potassium, and magnesium are known to affect calcium absorption and/or excretion; however, there is little research on whether various levels of dietary calcium can impact balance of these minerals. The objective of this study was to determine how different dietary calcium intakes could potentially affect urinary and fecal excretion of potassium, sodium, and magnesium. Thirty‐seven boys aged 12‐15 y participated in 3‐wk metabolic balance studies testing a range (700‐2100 mg/d) of calcium intakes in a crossover study design with a 2‐wk washout period. All subjects were fed the same controlled diet with adjustments in calcium intake. Each boy received a high and a low calcium diet during separate trials. Calcium, potassium, sodium, and magnesium excretion in urine and feces was determined during the final two weeks of each trial period. As previously reported, significantly more calcium was excreted in the urine and feces during higher calcium intake. Fecal excretion of sodium excretion was greater (p &lt; 0.042) during lower calcium consumption. Urinary and fecal magnesium retention tended to be greater during higher calcium intake; however, the differences were significant (p &lt; 0.033) only for urinary losses. Varying levels of dietary calcium intake did not significantly affect urinary or fecal potassium losses. In summary, fecal sodium excretion was higher during lower calcium intake, and reduced urinary magnesium losses were observed with higher calcium intake.

Gut hormones in the treatment of short-bowel syndrome and intestinal failure.

The approval of teduglutide, a recombinant analog of human glucagon-like peptide (GLP) 2, by the US Food and Drug Administration (Gattex) and the European Medicines Agency (Revestive) has illustrated the potential of selected gut hormones as treatments in patients with short-bowel syndrome and intestinal failure. Gut hormones may improve the structural and functional intestinal adaptation following intestinal resection by decreasing a rapid gastric emptying and hypersecretion, by increasing the intestinal blood flow, and by promoting intestinal growth. This review summarizes the findings from phase 2 and 3 teduglutide studies, and pilot studies employing GLP-1 and agonists for this orphan condition. In a 3-week, phase 2, metabolic balance study, teduglutide increased the intestinal wet weight absorption by approximately 700 g/day and reduced fecal energy losses by approximately 0.8 MJ/day (∼200 Kcal/day). In two subsequent 24-week, phase 3 studies, teduglutide reduced the need for parenteral support in the same magnitude. Adverse events were mainly of gastrointestinal origin and consistent with the known mechanism of action of teduglutide. Pilot studies suggest that GLP-1 may be less potent. Synergistic effects may be seen by co-treatment with GLP-2. Gut hormones promote intestinal adaptation and absorption, decreasing fecal losses, thereby decreasing or even eliminating the need for parenteral support. This will aid the intestinal rehabilitation in these severely disabled short-bowel syndrome patients.

Abstract 308: Nephron Specific Deletion Of Angiotensinogen Modulates Blood Pressure

It is unknown if intrarenal generation of angiotensinogen (AGT) is important in blood pressure (BP) regulation. Previous studies showed that proximal tubule-specific overexpression of AGT increases BP, while proximal tubule-specific deletion of AGT using the KAP promoter-Cre transgene did not alter BP. The latter study may not have completely eliminated nephron AGT production; in addition, BP was only assessed on a normal salt diet. To evaluate this issue in greater detail, we developed mice with inducible nephron-wide AGT deletion. Mice were generated which were hemizygous for the Pax8-rtTA and LC-1 transgenes and homozygous for loxP flanked AGT alleles to achieve nephron-specific AGT disruption after doxycycline induction. Adult Pax8-rtTA/LC-1/floxed AGT mice at 3 months of age were treated with doxycycline 2 mg/ml in drinking water for 11 days and studied 4 weeks after treatment. Blood pressure (recorded via telemetry) and metabolic balance studies were determined during 5 days of normal, high and low Na diets. Compared to controls, AGT knockout (KO) mice demonstrated significantly lower systolic, diastolic, and mean BPs on all three diets (N=4 each group). The BP reduction was most evident on a low Na diet (mean BP 107 ± 2 mmHg in controls and 88 ± 13 mmHg in AGT KO). Plasma renin concentration was higher in the AGT KO mice as compared to controls on all three diets. There were no detectable differences in weight, urine volume, urine osmolality or urine Na excretion between the controls and KO mice on all three diets, however due to variability, small differences in these parameters may not have been detected. Taken together, these data suggest that nephron AGT may contribute to BP regulation and this is most evident during low Na intake.