Suboptimal Weight Loss 13 Years After Roux-en-Y Gastric Bypass Is Associated with Blunted Appetite Response.

PURPOSE: Bariatric surgery remains the most efficient treatment to achieve a sustained weight loss. However, a large proportion of patients experience suboptimal weight loss (SWL). The exact mechanisms involved remain to be fully elucidated, but the homeostatic appetite control system seems to be involved. The aim of this study was, therefore, to compare the plasma concentration of gastrointestinal hormones, and appetite ratings, between those experiencing SWL and optimal weight loss (OWL) after Roux-en-Y gastric bypass (RYGB). MATERIALS AND METHODS: Fifty participants from the Bariatric Surgery Observation Study (BAROBS) experiencing either SWL or OWL (< or ≥ 50% of excess weight loss (EWL), respectively) > 13 years post-RYGB were compared to 25 non-surgical controls. Plasma concentrations of acylated ghrelin (AG), total glucagon-like peptide-1 (GLP-1), total peptide YY (PYY), cholecystokinin (CCK), and subjective ratings of hunger, fullness, desire to eat (DTE), and prospective food consumption (PFC) were assessed in the fasting and postprandial (area under the curve (AUC)) states. RESULTS: Those experiencing OWL presented with higher basal AG and GLP-1 iAUC, and lower AG iAUC compared with SWL and controls. Additionally, both bariatric groups presented with higher PYY and CCK iAUC compared to controls. PFC tAUC was also lower in OWL compared to the SWL group. Total weight loss was positively correlated with GLP-1 tAUC and negatively correlated with fasting and tAUC DTE and PFC tAUC. CONCLUSIONS: SWL > 13 years post-RYGB is associated with lower basal ghrelin, as well as a weaker satiety response to a meal. Future studies should investigate the causality of these associations.

Effects of Quinine on the Glycaemic Response to, and Gastric Emptying of, a Mixed-Nutrient Drink in Females and Males.

Intraduodenal quinine, in the dose of 600 mg, stimulates glucagon-like peptide-1 (GLP-1), cholecystokinin and insulin; slows gastric emptying (GE); and lowers post-meal glucose in men. Oral sensitivity to bitter substances may be greater in women than men. We, accordingly, evaluated the dose-related effects of quinine on GE, and the glycaemic responses to, a mixed-nutrient drink in females, and compared the effects of the higher dose with those in males. A total of 13 female and 13 male healthy volunteers received quinine-hydrochloride (600 mg ('QHCl-600') or 300 mg ('QHCl-300', females only) or control ('C'), intraduodenally (10 mL bolus) 30 min before a drink (500 kcal, 74 g carbohydrates). Plasma glucose, insulin, C-peptide, GLP-1, glucose-dependent insulinotropic polypeptide (GIP) and cholecystokinin were measured at baseline, for 30 min after quinine alone, and then for 2 h post-drink. GE was measured by 13C-acetate breath-test. QHCl-600 alone stimulated insulin, C-peptide and GLP-1 secretion compared to C. Post-drink, QHCl-600 reduced plasma glucose, stimulated C-peptide and GLP-1, and increased the C-peptide/glucose ratio and oral disposition index, while cholecystokinin and GIP were less, in females and males. QHCl-600 also slowed GE compared to C in males and compared to QHCl-300 in females (p < 0.05). QHCl-300 reduced post-meal glucose concentrations and increased the C-peptide/glucose ratio, compared to C (p < 0.05). Magnitudes of glucose lowering and increase in C-peptide/glucose ratio by QHCl-600 were greater in females than males (p < 0.05). We conclude that quinine modulates glucoregulatory functions, associated with glucose lowering in healthy males and females. However, glucose lowering appears to be greater in females than males, without apparent differential effects on GI functions.

Primary weight loss failure after Roux-en-Y gastric bypass is characterized by impaired gut-hormone mediated regulation of food intake.

BACKGROUND/OBJECTIVES: After Roux-en-Y gastric bypass (RYGB) a subset of patients never obtain excess BMI loss (EBMIL) > 50% and are categorized as having primary weight loss (WL) failure. We hypothesized that postprandial concentrations of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) would be lower in patients with primary WL failure compared with patients with successfully maintained WL. Furthermore, that inhibition of gut hormone secretions would increase ad libitum food intake less in patients with primary WL failure. SUBJECTS/METHODS: Twenty women with primary WL failure (LowEBMIL < 50%) were individually matched to twenty women with successful WL (HighEBMIL > 60%) on age, preoperative BMI and time from RYGB. On separate days performed in a random order, patient-blinded subcutaneous injections of octreotide or saline (placebo) were followed by a fixed breakfast and an ad libitum lunch with blood sampling for appetite regulating hormones and Visual-Analogue-Scale (VAS)-scoring of hunger/satiety. Furthermore, participants underwent gene variant analysis for GLP-1, PYY and their receptors, indirect calorimetry, dual-energy X-ray absorptiometry (DXA)-scans, 4-days at-home food registration and 14-days step counting. RESULTS: On placebo days, postprandial GLP-1, PYY and cholecystokinin (CCK) concentrations were similar between groups after breakfast. Fasting ghrelin was lower in LowEBMIL, but the postprandial suppression was similar. LowEBMIL had lower satiety VAS-scores and less suppression of hunger VAS-scores. Gene variants did not differ between groups. Octreotide diminished GLP-1, PYY, CCK and ghrelin concentrations in both groups. Octreotide did not affect ad libitum food intake in LowEBMIL (-1% [-13, 12], mean [95%CI]), while food intake increased in HighEBMIL (+23% [2,44]). CONCLUSIONS: Primary WL failure after RYGB was not characterized by impaired secretions of appetite regulating gut hormones. Interestingly, inhibition of gut hormone secretions with octreotide only increased food intake in patients with successful WL post-RYGB. Thus, an impaired central anorectic response to gut hormones may contribute to primary WL failure after RYGB.

Gastrointestinal hormones and appetite ratings after weight loss induced by diet or bariatric surgery.

OBJECTIVE: The aim of this study was to compare changes in gastrointestinal hormones and appetite ratings after a similar weight loss induced by a very low-energy diet alone or in combination with sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB). METHODS: Patients with severe obesity scheduled for SG (n = 15) and RYGB (n = 14) and 15 controls (very low-energy diet alone) were recruited. Body weight/composition, plasma concentrations of ß-hydroxybutyric acid, acylated ghrelin, total glucagon-like peptide-1, total peptide YY, cholecystokinin, and ratings of hunger, fullness, desire to eat, and prospective food consumption were measured pre- and postprandially, before and after 10 weeks of intervention. RESULTS: Changes in body weight/composition and level of ketosis were similar across groups. In SG and RYGB, basal and postprandial acylated ghrelin declined, and postprandial glucagon-like peptide-1 increased, both significantly more compared with controls. Postprandial peptide YY increased in all groups. Overall, postprandial hunger decreased, and postprandial fullness increased. But ratings of desire to eat and prospective food consumption were more favorable after both surgeries compared with controls. CONCLUSIONS: Weight loss with SG and RYGB leads to more favorable changes in gastrointestinal hormones compared with diet alone, although ratings of appetite were reduced across all groups.

Differences in gastrointestinal hormones and appetite ratings among obesity classes.

The aim of this study was to compare gastrointestinal (GI) hormones and subjective ratings of appetite among obesity classes, and between classes of obesity and controls. Ninety-eight adult individuals with obesity, divided into class I (n = 35), II (n = 44) and III (n = 19), together with 45 controls without obesity were included in this cross-sectional analysis. Body weight/composition, and basal and postprandial (after a 600 kcal fixed breakfast) plasma concentrations of acylated ghrelin, active glucagon-like peptide 1 (GLP-1), total peptide YY (PYY), cholecystokinin (CCK) and insulin, as well as subjective ratings of hunger, fullness, desire to eat (DTE) and prospective food consumption (PFC) were measured. There were no differences in the plasma concentration of GI hormones (either basal or postprandial) among obesity classes, except for insulin. In general, obesity was associated with impaired secretion of GI hormones. Ghrelin secretion did not decline postprandially in class-III obesity. GLP-1 peak for obesity class I and II was early and lower, while class III showed no postprandial GLP-1 response. Postprandial PYY response for obesity class II and III was absent, and class III showed a delayed and shortened postprandial CCK response. Obesity class II and III had greater basal insulin concentration compared to controls and postprandial insulin was greater in obesity class III versus class II, class I and controls. No differences were found for appetite ratings among obesity classes. In conclusion, obesity is characterized by impaired secretion of GI hormones, with reduced postprandial satiety, particularly in individuals with obesity class III. This abnormal pattern may lead to overeating.

Bile acid-farnesoid X receptor-fibroblast growth factor 19 axis in patients with short bowel syndrome: The randomized, glepaglutide phase 2 trial.

BACKGROUND: The gut-liver axis and enterohepatic circulation have gained increasing attention lately. Patients with short bowel syndrome (SBS) are, in fact, human knock-out models that may assist in the understanding of bile acid synthesis and regulation. We evaluated effect of glepaglutide (a long-acting glucagon-like peptide-2 analog) on bile acid synthesis (the enterohepatic circulation of bile acids and liver biochemistry in patients with SBS). METHOD: In a single-center, double-blinded, dose-finding, crossover phase 2 trial, 18 patients with SBS were randomly assigned to 2 of 3 treatment arms (0.1, 1, and 10 mg) with daily subcutaneous injections of glepaglutide for 3 weeks. The washout period between the 2 treatment periods was 4-8 weeks. Measurements were performed at baseline and at the end of each treatment period and included postprandial plasma samples for fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), total excretion of fecal bile acids, gene expression of farnesoid X receptor (FXR) in intestinal mucosal biopsies, total plasma bile acids, and liver biochemistry. RESULTS: Compared with baseline, the median (interquartile range) postprandial response (area under the curve 0-2h) of FGF19 increased by 150 h × ng/L (41, 195; P = 0.001) and C4 decreased by 82 h × µg/L (-169, -28; p = 0.010) in the 10-mg dose. FXR gene expression did not change in any of the groups. Alkaline phosphatase significantly decreased. CONCLUSION: Glepaglutide may stimulate the bile acid/FXR/FGF19 axis, leading to increased plasma concentrations of FGF19. Thereby, glepaglutide may ameliorate the accelerated de novo bile acid synthesis and play a role in the prevention and/or treatment of intestinal failure-associated liver disease.

Oral D/L-3-Hydroxybutyrate Stimulates Cholecystokinin and Insulin Secretion and Slows Gastric Emptying in Healthy Males.

BACKGROUND: D-3-hydroxybutyrate (D-3-OHB) is a ketone body that serves as an alternative nutritional fuel but also as an important signaling metabolite. Oral ketone supplements containing D/L-3-OHB are becoming a popular approach to achieve ketosis. AIM: To explore the gut-derived effects of ketone supplements. METHODS: Eight healthy lean male volunteers were investigated on 2 separate occasions:An acetaminophen test was performed to evaluate gastric emptying and blood samples were obtained consecutively throughout the study period. RESULTS: We show that oral consumption of D/L-3-OHB stimulates cholecystokinin release (P = 0.02), elevates insulin (P = 0.03) and C-peptide (P < 0.001) concentrations, and slows gastric emptying (P = 0.01) compared with matched intravenous D/L-3-OHB administration. Measures of appetite and plasma concentrations of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) were unaffected by interventions. CONCLUSION: Our findings show that D/L-3-OHB exert incretin effects and indicate luminal sensing in the gut endothelium. This adds to our understanding of ketones as signaling metabolites and displays the important difference between physiological ketosis and oral ketone supplements.

Changes in the Homeostatic Appetite System After Weight Loss Reflect a Normalization Toward a Lower Body Weight.

OBJECTIVE: To compare appetite markers in reduced-obese individuals with a nonobese control group. METHODS: A total of 34 adults with obesity who lost 17% body weight at week 13 and maintained this weight loss (WL) at 1 year were compared with 33 nonobese controls matched for body composition. Basal and postprandial subjective appetite ratings and appetite-related hormone concentrations (ghrelin, total peptide YY, peptide YY3-36, total and active glucagon-like peptide 1, and cholecystokinin) were measured in all participants and repeated at week 13 and 1 year in the weight-reduced group. RESULTS: WL led to a reduction in prospective food consumption and an increase in feelings of hunger, fullness, and ghrelin secretion (basal and postprandial), but these new ratings were no different from those seen in controls. Postprandial concentrations of active glucagon-like peptide 1, total peptide YY, and cholecystokinin were lower in individuals with obesity at all time points compared with controls. CONCLUSION: The increased drive to eat (both subjective feelings of hunger and ghrelin concentrations) seen in reduced-obese individuals, both after acute and sustained WL, reflects a normalization toward a lower body weight. Overall, WL does not have a sustained negative impact on satiety peptide secretion, despite a blunted secretion in individuals with obesity compared with nonobese controls.

Responses of gut and pancreatic hormones, bile acids, and fibroblast growth factor-21 differ to glucose, protein, and fat ingestion after gastric bypass surgery.

Postprandial gut hormone responses change after Roux-en-Y gastric bypass (RYGB), and we investigated the impact of glucose, protein, and fat (with and without pancreas lipase inhibition) on plasma responses of gut and pancreas hormones, bile acids, and fibroblast growth factor 21 (FGF-21) after RYGB and in nonoperated control subjects. In a randomized, crossover study 10 RYGB operated and 8 healthy weight-matched control subjects were administered 4 different 4-h isocaloric (200 kcal) liquid meal tests containing >90 energy (E)% of either glucose, protein (whey protein), or fat (butter with and without orlistat). The primary outcome was glucagon-like peptide-1 (GLP-1) secretion (area under the curve above baseline). Secondary outcomes included responses of peptide YY (PYY), glucose-dependent insulinotropic polypeptide (GIP), cholecystokinin (CCK), glicentin, neurotensin, ghrelin, insulin, glucagon, bile acids, and FGF-21. In the RYGB group the responses of GLP-1, GIP, glicentin, FGF-21, and C-peptide were increased after glucose compared with the other meals. The neurotensin and bile acids responses were greater after fat, while the glucagon and CCK responses were greater after protein ingestion. Furthermore, compared with control subjects, RYGB subjects had greater responses of total PYY after glucose, glucagon after glucose and fat, glicentin after glucose and protein, and GLP-1 and neurotensin after all meals, while GIP and CCK responses were lower after fat. Ghrelin responses did not differ between meals or between groups. Orlistat reduced all hormone responses to fat ingestion, except for ghrelin in the RYGB group. In conclusion, after RYGB glucose is a more potent stimulator of most gut hormones, especially for the marked increased secretion of GLP-1 compared with fat and protein.NEW & NOTEWORTHY We investigated the impact of glucose, protein, and fat meals on intestinal and pancreatic hormones, bile acid, and fibroblast growth factor 21 (FGF-21) secretion in gastric bypass-operated patients compared with matched nonoperated individuals. The fat meal was administered with and without a pancreas lipase inhibitor. We found that the impact of the different meals on gut hormones, bile, and FGF 21 secretion differ and was different from the responses observed in nonoperated control subjects.

Comparing olive oil and C4-dietary oil, a prodrug for the GPR119 agonist, 2-oleoyl glycerol, less energy intake of the latter is needed to stimulate incretin hormone secretion in overweight subjects with type 2 diabetes.

BACKGROUND/OBJECTIVE: After digestion, dietary triacylglycerol stimulates incretin release in humans, mainly through generation of 2-monoacylglycerol, an agonist for the intestinal G protein-coupled receptor 119 (GPR119). Enhanced incretin release may have beneficial metabolic effects. However, dietary fat may promote weight gain and should therefore be restricted in obesity. We designed C4-dietary oil (1,3-di-butyryl-2-oleoyl glycerol) as a 2-oleoyl glycerol (2-OG)-generating fat type, which would stimulate incretin release to the same extent while providing less calories than equimolar amounts of common triglycerides, e.g., olive oil. SUBJECTS AND METHODS: We studied the effect over 180 min of (a) 19 g olive oil plus 200 g carrot, (b) 10.7 g C4 dietary oil plus 200 g carrot and (c) 200 g carrot, respectively, on plasma responses of gut and pancreatic hormones in 13 overweight patients with type 2 diabetes (T2D). Theoretically, both oil meals result in formation of 7.7 g 2-OG during digestion. RESULTS: Both olive oil and C4-dietary oil resulted in greater postprandial (P ≤ 0.01) glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) responses (incremental area under curve (iAUC)): iAUCGLP-1: 645 ± 194 and 702 ± 97 pM × min; iAUCGIP: 4,338 ± 764 and 2,894 ± 601 pM × min) compared to the carrot meal (iAUCGLP-1: 7 ± 103 pM × min; iAUCGIP: 266 ± 234 pM × min). iAUC for GLP-1 and GIP were similar for C4-dietary oil and olive oil, although olive oil resulted in a higher peak value for GIP than C4-dietary oil. CONCLUSION: C4-dietary oil enhanced secretion of GLP-1 and GIP to almost the same extent as olive oil, in spite of liberation of both 2-OG and oleic acid, which also may stimulate incretin secretion, from olive oil. Thus, C4-dietary oil is more effective as incretin releaser than olive oil per unit of energy and may be useful for dietary intervention.

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

BACKGROUND: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Cholecystokinin-Induced Gallbladder Emptying and Metformin Elicit Additive Glucagon-Like Peptide-1 Responses.

CONTEXT: Bile acids have been suggested to mediate glucagon-like peptide-1 (GLP-1) secretion. Metformin, too, has been shown to increase GLP-1 levels. The effect of gallbladder emptying, metformin, or a combination has, however, never been studied. OBJECTIVE: We hypothesized that cholecystokinin (CCK)-8-induced gallbladder emptying stimulates human GLP-1 secretion and that metformin would potentiate this effect. DESIGN: A double-blinded, randomized study. SETTING: The study was conducted at a specialized research unit. PARTICIPANTS: Ten healthy male subjects with no family history of diabetes (age, 22 [range, 20-32] years; body mass index, 21.7 [19.3-24.2] kg/m(2); fasting plasma glucose, 4.9 [4.7-5.3] mm; and glycosylated hemoglobin A1c, 5.1 [4.4-5.8] %). INTERVENTION: On 4 separate days, the subjects received metformin or placebo and a concomitant 60-minute intravenous infusion of saline or CCK. Blood was sampled for 4 hours, and gallbladder volume was measured by ultrasound. MAIN OUTCOME MEASURES: Plasma levels of GLP-1. RESULTS: CCK-induced gallbladder emptying and metformin alone (no observed effect on gallbladder emptying) both elicited significant and additive GLP-1 responses. Metformin alone or combined with gallbladder emptying elicited a significant peptide YY response. CCK-induced gallbladder emptying resulted in a short-lasting glucose-dependent insulinotropic polypeptide response independent of metformin. No effects were seen on plasma glucose, insulin, C-peptide, or gastrin. CONCLUSIONS: CCK-induced gallbladder emptying in healthy subjects elicits significant GLP-1 secretion, which can be potentiated by metformin.

Peptide production and secretion in GLUTag, NCI-H716, and STC-1 cells: a comparison to native L-cells.

GLUTag, NCI-H716, and STC-1 are cell lines that are widely used to study mechanisms underlying secretion of glucagon-like peptide-1 (GLP-1), but the extent to which they resemble native L-cells is unknown. We used validated immunoassays for 14 different hormones to analyze peptide content (lysis samples; n = 9 from different passage numbers) or peptide secretion in response to buffer (baseline), and after stimulation with 50 mM KCl or 10 mM glucose + 10 µM forskolin/3-isobutyl-1-methylxanthine (n = 6 also different passage numbers). All cell lines produced and processed proglucagon into GLP-1, GLP-2, glicentin, and oxyntomodulin in a pattern (prohormone convertase (PC)1/3 dependent) similar to that described for human gut. All three cell lines showed basal secretion of GLP-1 and GLP-2, which increased after stimulation. In contrast to freshly isolated murine L-cells, all cell lines also expressed PC2 and secreted large amounts of pancreatic glucagon. Neurotensin and somatostatin storage was low and secretion was not consistently increased by stimulation. STC-1 cells released more glucose-dependent insulinotropic polypeptide than GLP-1 at baseline (P < 0.01) and KCl elevated its secretion (P < 0.05). Peptide YY, which normally co-localizes with GLP-1 in distal L-cells, was not detected in any of the cell lines. GLUTag and STC-1 cells also expressed vasoactive intestinal peptide, but none expressed pancreatic polypeptide or insulin. GLUTag contained and secreted large amounts of CCK, while NCI-H716 did not store this peptide and STC-1 contained low amounts. Our results show that hormone production in cell line models of the L-cell has limited similarity to the natural L-cells.

Characterization of gastrins and their receptor in solid human gastric adenocarcinomas.

OBJECTIVE: The gastrin and the gastrin/CCK-B receptor genes are co-expressed in several carcinomas. The primary translational product, progastrin, however, is processed to several peptides of which only those that are α-amidated at their C-terminus are receptor ligands. So far, characterization of the progastrin-derived peptides in gastric cancer has not been reported. The authors therefore examined the molecular nature of gastrin and its receptor in human gastric carcinomas. MATERIALS AND METHODS: Twenty patients with adenocarcinoma underwent partial or total gastrectomy. In samples from each carcinoma, gastrin peptides were characterized, using a library of sequence-specific immunoassays. Expression was also demonstrated by immunohistochemistry. In addition, the gastrin and gastrin/CCK-B receptor gene expression was quantitated using real-time PCR, and the receptor protein demonstrated by western blotting. RESULTS: α-Amidated gastrins were detectable in 16 of 20 carcinomas (median concentration 2.1 pmol/g tissue; range 0-386 pmol/g tissue). The tissue concentrations correlated closely to the gastrin mRNA contents (r = 0.75, p < 0.0001). Moreover, progastrin and non-amidated processing intermediates, including glycine-extended gastrins, were detected in 19 carcinomas. Immunohistochemistry corroborated gastrin expression in carcinoma cells. Chromatography revealed extensive progastrin processing with α-amidated gastrin-34 and -17 (tyrosyl-sulfated as well as non-sulfated) as major products. Finally, gastrin/CCK-B receptor mRNA and protein were detected in all tumors. CONCLUSIONS: The results show that the elements for a local loop of α-amidated gastrins and their receptor are detectable in 80% of human gastric adenocarcinomas. Therefore, the results support the contention that locally expressed gastrin may be involved in the tumorigenesis of gastric adenocarcinomas.

Processing-independent analysis of peptide hormones and prohormones in plasma.

Peptide hormones are post-translationally matured before they reach a structure in which they can fulfill their biological functions. The prohormone processing may encompass a variety of endoproteolytic cleavages, N- and C-terminal trimmings, and amino acid derivatizations. The same prohormone can be variably processed in different cell types and, in addition, diseased cells often change the processing of a given precursor. The translational process is often either increased or decreased in diseased cells, which renders the ensuing modifications of the prohormone incomplete. Consequently, a variable mixture of precursors and processing-intermediates accumulates in plasma. In order to exploit disturbed posttranslational processing for diagnostic use and at the same time provide an accurate measure of the translational product, a simple analytical principle named "processing-independent analysis" (PIA) was designed. PIA-methods quantitate the total mRNA product irrespective of the degree of processing. PIA-methods have now been developed for a number of prohormones and proteins, and their diagnostic potential appears promising in diagnosis of cardiovascular disease and in several malignancies.

Effect of dairy calcium or supplementary calcium intake on postprandial fat metabolism, appetite, and subsequent energy intake.

BACKGROUND: High calcium intake has been shown to increase fecal fat excretion. OBJECTIVE: Our aim was to examine whether a high calcium intake from dairy products or from supplements affects postprandial fat metabolism and appetite through fat malabsorption. DESIGN: Four different isocaloric meals were tested in 18 subjects according to a randomized crossover design. The test meals contained high (HC meal: 172 mg/MJ), medium (MC meal: 84 mg/MJ), or low (LC meal: 15 mg/MJ) amounts of calcium from dairy products or a high amount of calcium given as a calcium carbonate supplement (Suppl meal: 183 mg/MJ). Concentrations of plasma total triacylglycerol, chylomicron triacylglycerol, serum total cholesterol, HDL cholesterol, cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, glucose, and insulin and appetite sensation were measured before and at regular intervals until 420 min postprandially. RESULTS: Dairy calcium significantly diminished the postprandial lipid response. The baseline adjusted area under the curve for chylomicron triacylglycerol was approximately 17% lower after the MC meal (P = 0.02) and approximately 19% lower after the HC meal (P = 0.007) than after the LC meal and approximately 15% lower after the MC meal (P = 0.0495) and approximately 17% lower after the HC meal (P = 0.02) than after the Suppl meal. No consistent effects of calcium on appetite sensation, or on energy intake at the subsequent meal, or on the postprandial responses of cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, insulin, or glucose were observed. CONCLUSIONS: Increased calcium intakes from dairy products attenuate postprandial lipidemia, most probably because of reduced fat absorption, whereas supplementary calcium carbonate does not exert such an effect. This may be due to differences in the chemical form of calcium or to cofactors in dairy products. Calcium did not affect appetite sensation, glucose metabolism, or gut hormone secretion.