Clinical studies have indicated that circulating bile acid (BA) concentrations increase following bariatric surgery, especially following malabsorptive procedures such as Roux-en-Y gastric bypasses (RYGB). Moreover, total circulating BA concentrations in patients following RYGB are positively correlated with serum glucagon-like peptide-1 concentrations and inversely correlated with postprandial glucose concentrations. Overall, these data suggest that the increased circulating BA concentrations following bariatric surgery - independently of calorie restriction and body-weight loss - could contribute, at least in part, to improvements in insulin sensitivity, incretin hormone secretion, and postprandial glycemia, leading to the remission of type-2 diabetes (T2DM). In humans, the primary and secondary BA pool size is dependent on the rate of biosynthesis and the enterohepatic circulation of BAs, as well as on the gut microbiota, which play a crucial role in BA biotransformation. Moreover, BAs and gut microbiota are closely integrated and affect each other. Thus, the alterations in bile flow that result from anatomical changes caused by bariatric surgery and changes in gut microbiome may influence circulating BA concentrations and could subsequently contribute to T2DM remission following RYGB. Research data coming largely from animal and cell culture models suggest that BAs can contribute, via nuclear farnezoid X receptor (FXR) and membrane G-protein-receptor (TGR-5), to beneficial effects on glucose metabolism. It is therefore likely that FXR, TGR-5, and BAs play a similar role in glucose metabolism following bariatric surgery in humans. The objective of this review is to discuss in detail the results of published studies that show how bariatric surgery affects glucose metabolism and subsequently T2DM remission.

Background Bariatric surgery contributes to the improvement in glucose metabolism that may be related to a postoperative increase in serum bile acids (BAs). Three commonly used types of bariatric procedures, laparoscopic sleeve gastrectomy (LSG) (without creation of a bile loop), Roux-en-Y gastric bypass (RYGB), and omega-loop gastric bypass (OLGB) (with creation of shorter 100-150 cm and longer 200-280 cm bile loops, respectively), differ in their effects on glycemic control. The aim of the study was to compare the effects of various bariatric procedures on serum BA concentration and glucose homeostasis. Methods Serum BAs in 26 obese patients were determined by liquid chromatography-mass spectrometry prior to bariatric surgery, as well as 4 days and 3 months thereafter. Results Four days after the surgery, serum concentrations of BAs in LSG and OLGB groups were similar as prior to the procedure, and a slight decrease in serum BAs was observed in the RYGB group. Serum BA level in the LSG group remained unchanged also at 3 months after the surgery, whereas a significant 0.5-and 3-fold increase in this parameter was noted in the RYGB and OLGB groups, respectively. Serum concentration of BAs correlated positively with the length of the bile loop (R = 0.47, p < 0.05). Conclusion The evident improvement of glycemic control observed 3 months after OLGB might be associated with a postoperative increase in serum BAs, resulting from their better absorption from the longer bile loop. However, the changes in serum BAs probably had little or no impact on insulin sensitivity improvement at 4 days post-surgery.

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Background/Aims: Occurring in marine invertebrates infectious haemic neoplasia (bivalves transmissible neoplasia, BTN) arises from genome instabilities leading to multilevel malfunctions and unregulated cell division of presumably haemocyte precursors. As its biochemical characterisation remains unknown, we here present the first data describing selected aspects of the physiology and biochemistry of the disease a in model clam Macoma balthica. We chose free amino acids (FAA) composition, mitochondrial respiration and enzymatic activity, oxidative stress enzymes activities and corticosteroids profile as markers of this contagious cancer. Methods: Selected markers were measured in neoplastic and healthy clams and two tissue types, haemolymph and solid tissue. FAA composition was assessed in the haemolymph samples using high performance liquid chromatography-mass spectrometry (LC/MS). Mitochondrial respiration analysis was performed on haemocytes using oxygen electrodes integrated system Seahorse XFp. Mitochondrial enzymes activities were measured using spectrophotometry (cytochrome oxidase, COX) and commercial kit (succinate dehydrogenase, SDH). Total Antioxidant Capacity (TAC), Acetylocholinesterase (AChE), Protein Carbonyl Content (CBO) and Malondialdehyde (MDA) levels were measured in the solid tissue using analytical kits, and glutathione (GSH) was measured spectrophotometrically. Corticosteroids profile, measured in the solid tissue, was obtained with Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (HPLC–ESI-MS/MS) technique. Results: In both clam groups nine FAAs were detected with Asp, Glu, Pro, Ser constituting over 90% of total FAA content. Significantly higher Gln level was detected in BTN positive clams. In neoplastic clams, an impairment of mitochondrial metabolism was observed as a decrease in mitochondrial oxygen consumption and lower cytochrome c oxidase activity. In the neoplastic clams significantly higher concentration of low molecular weight antioxidants was found. Finally, we report high level of corticosterone and lower levels of dehydrocorticosterone, cortisol and cortisone in healthy clams and elevated cortisol level in BTN individuals. Conclusion: Neoplastic clams are characterized by altered mitochondrial metabolism, with a potential key role of glutamine (Gln) in cancer cells energy production. Despite low aerobic respiration, BTN cells have efficient antioxidative response to elevated concentration of ROS. Elevated cortisol level in BTN-positive clams may indicate an important role of this corticosteroid in cancer biochemistry. Thus, we here provide the first results of selected physiological and biochemical aspects of BTN, making an important step in studying cancer epidemiology in wildlife.