Effect of creatine on the pancreatic beta-cell

Observing exocrine pancreas metabolism using a novel pancreas perfusion technique in combination with hyperpolarized [1-13 C]pyruvate

In a clinical setting, ex vivo perfusions are routinely used to maintain and assess organ viability prior to transplants. Organ perfusions are also a model system to examine metabolic flux while retaining the local physiological structure, with significant success using hyperpolarized (HP) 13 C NMR in this context. We use a novel exocrine pancreas perfusion technique via the common bile duct to assess acinar cell metabolism with HP [1-13 C]pyruvate. The exocrine component of the pancreas produces digestive enzymes through the ductal system and is often neglected in research on the pancreas. Real-time production of [1-13 C]lactate, [1-13 C]alanine, [1-13 C]malate, [4-13 C]malate, [1-13 C]aspartate, and H13 CO3 - was detected. The appearance of these resonances indicates flux through both pyruvate dehydrogenase and pyruvate carboxylase. We studied excised pancreata from C57BL/6J mice and NOD.Rag1-/- .AI4α/β mice, a commonly used model of Type 1 Diabetes (T1D). Pancreata from the T1D mice displayed increased lactate to alanine ratio without changes in oxygen consumption, signifying increased cytosolic NADH levels. The mass isotopologue analysis of the extracted pancreas tissue using gas chromatography-mass spectrometry revealed confirmatory 13 C enrichment in multiple TCA cycle metabolites that are products of pyruvate carboxylation. The methodology presented here has the potential to provide insight into mechanisms underlying several pancreatic diseases, such as diabetes, pancreatitis, and pancreatic cancer.

Expeller-Pressed Canola (Brassica napus) Meal Modulates the Structure and Function of the Cecal Microbiota, and Alters the Metabolome of the Pancreas, Liver, and Breast Muscle of Broiler Chickens

The inoculation of one-day-old broiler chicks with the cecal contents from a mature broiler breeder resulted in a highly diverse and uniform cecal bacterial community. CM did not affect feed consumption, weight gain, nor the richness, evenness, or diversity of the cecal bacterial community. However, the structure of the bacterial community was altered in birds fed the CM diet. Although the CM diet was formulated to contain equivalent metabolizable energy to the control diet, it contained more dietary fiber. The abundance of bacterial families, including those that are known to contain species able to metabolize fiber was altered (e.g., bacteria within the families, Methanobacteriaceae, Atopobiaceae, Prevotellaceae, Clostridiales Family XIII, Peptostreptococcaceae, and Succinivibrionaceae), and concentrations of SCFAs were higher in the ceca of birds fed the CM diet. Moreover, concentrations of isoleucine, isobutyrate, glutamate, and 2-oxoglutarate were higher, whereas concentrations of phenyllactic acid, indole, glucose, 3-phenylpropionate, and 2-oxobutyrate were lower in the digesta of chickens that were fed CM. The metabolic profiles of pancreas, liver, and breast muscle tissues of birds fed the CM diet differed from control birds. Metabolites that were associated with energy production, protection against oxidative stress, and pathways of amino acid and glycerophospholipid metabolism had altered concentrations in these tissues. Some of the observed changes in metabolite levels may indicate an increased disease risk in birds fed the CM diet (e.g., pancreatitis), and others suggested that birds mounted metabolic response to offset the adverse impacts of CM (e.g., oxidative stress in the liver).

Library-assisted nonlinear blind separation and annotation of pure components from a single 1H nuclear magnetic resonance mixture spectra

Due to its capability for high-throughput screening ¹H nuclear magnetic resonance (NMR) spectroscopy is commonly used for metabolite research. The key problem in ¹H NMR spectroscopy of multicomponent mixtures is overlapping of component signals and that is increasing with the number of components, their complexity and structural similarity. It makes metabolic profiling, that is carried out through matching acquired spectra with metabolites from the library, a hard problem. Here, we propose a method for nonlinear blind separation of highly correlated components spectra from a single ¹H NMR mixture spectra. The method transforms a single nonlinear mixture into multiple high-dimensional reproducible kernel Hilbert Spaces (mRKHSs). Therein, highly correlated components are separated by sparseness constrained nonnegative matrix factorization in each induced RKHS. Afterwards, metabolites are identified through comparison of separated components with the library comprised of 160 pure components. Thereby, a significant number of them are expected to be related with diabetes type 2. Conceptually similar methodology for nonlinear blind separation of correlated components from two or more mixtures is presented in the Supplementary material. Single-mixture blind source separation is exemplified on: (i) annotation of five components spectra separated from one ¹H NMR model mixture spectra; (ii) annotation of fifty five metabolites separated from one ¹H NMR mixture spectra of urine of subjects with and without diabetes type 2. Arguably, it is for the first time a method for blind separation of a large number of components from a single nonlinear mixture has been proposed. Moreover, the proposed method pinpoints urinary creatine, glutamic acid and 5-hydroxyindoleacetic acid as the most prominent metabolites in samples from subjects with diabetes type 2, when compared to healthy controls.

Synthesis of guanidinoacetate and creatine from amino acids by rat pancreas

Creatine is an important molecule involved in cellular energy metabolism. Creatine is spontaneously converted to creatinine at a rate of 1·7% per d; creatinine is lost in the urine. Creatine can be obtained from the diet or synthesised from endogenous amino acids via the enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT). The liver has high GAMT activity and the kidney has high AGAT activity. Although the pancreas has both AGAT and GAMT activities, its possible role in creatine synthesis has not been characterised. In the present study, we examined the enzymes involved in creatine synthesis in the pancreas as well as the synthesis of guanidinoacetate (GAA) and creatine by isolated pancreatic acini. We found significant AGAT activity and somewhat lower GAMT activity in the pancreas and that pancreatic acini had measurable activities of both AGAT and GAMT and the capacity to synthesise GAA and creatine from amino acids. Creatine supplementation led to a decrease in AGAT activity in the pancreas, though it did not affect its mRNA or protein abundance. This was in contrast with the reduction of AGAT activity and mRNA and protein abundance in the kidney, suggesting that the regulatory mechanisms that control the expression of this enzyme in the pancreas are different from those in the kidney. Dietary creatine increased the concentrations of GAA, creatine and phosphocreatine in the pancreas. Unexpectedly, creatine supplementation decreased the concentrations of S-adenosylmethionine, while those of S-adenosylhomocysteine were not altered significantly.

Comparison of antihyperglycemic effects of creatine and glibenclamide in type II diabetic patients

This study compares the effects of glibenclamide and creatine in type II diabetics. In a 14-day symmetrically randomized crossover trial recently detected type II diabetics received either creatine (3 g) or glibenclamide (3.5 mg) for five successive days, followed by two days of washout, and crossover to the opposite treatment. Glucose, insulin, c-peptide, and creatine were measured. Creatine and glibenclamide decreased glucose concentrations vs. basal glucose [-15, 60, 90, 120, 180, and 240 min; mol/l]: 12.6±0.83 vs. 12.2±0.56 vs. 12.1±0.57, 15.3±0.63 vs. 13.5± 0.70(a ) vs. 13.0±0.57(a), 14.8±0.57 vs. 13.8±0.59(a) vs. 13.4±0.46(a), 14.6±0.61 vs. 12.3±0.49(b) vs. 12.4±0.61(a), 12.8±0.76 vs. 10.0± 0.40(c) vs. 10.3±0.41(c), and 11.4±0.67 vs. 8.3±0.40(c) vs. 8.5±0.36(c); ((a) p<0.05; (b) p<0.01; (c) p<0.001 vs. basal glucose). Treatment with both creatine and glibenclamide increased insulin and c-peptide concentrations after 120 and 240 min (p<0.05 and p<0.01). At the doses applied short-term treatment with creatine and glibenclamide elicits similar glucose lowering effects.

Active visfatin is elevated in serum of maintenance haemodialysis patients and correlates inversely with circulating HDL cholesterol

BACKGROUND

Increased circulating visfatin may be associated both with endothelial damage and with increased mortality in end-stage renal disease (ESRD). HDL cholesterol is an independent, strong inverse predictor of cardiovascular events. However, associations between visfatin and parameters of lipid metabolism are unclear. Moreover, serum concentrations of visfatin measured by an enzyme immuno assay (EIA) are conflicting and do not correlate with ELISA (enzyme-linked immunosorbent assay) data, which predominantly detect enzymatically active visfatin.

METHODS

A total of 74 haemodialysis (HD) patients and 35 control individuals (C) were studied. All subjects (mean age 62.9 years) provided fasted blood samples (HD patients after 66-69 h without dialysis). Circulating visfatin was measured by the ELISA. Body composition was evaluated using waist circumference, skinfold thickness and body impedance analysis. Results obtained by the ELISA were compared with EIA data.

RESULTS

Active serum visfatin was increased in HD (5.58 +/- 6.50 ng/ml) versus C [0.97 +/- 1.79 ng/ml, mean +/- SD; P < 0.0001 by multiple regression analysis (MRA)] independently of plasma glucose, serum insulin, diabetes, HDL cholesterol and body composition. Within the HD group, only plasma HDL cholesterol (4% lower per additional mg/dl HDL; P = 0.001) and insulin-treated diabetes mellitus [subgroup of n = 18; 119% higher compared with patients without diabetes (n = 40); P = 0.011] were independently (by MRA) associated with active serum visfatin. Visfatin measured by an EIA showed no correlation with ELISA data.

CONCLUSIONS

Our study provides reliable data on active visfatin in HD patients using a well-characterized ELISA. Loss of renal function is accompanied by increased circulating active visfatin concentrations in our patients. Furthermore, decreased HDL cholesterol may hint at an increased probability of cardiovascular events in HD patients with elevated serum visfatin.

Creatine and creatine kinase in health and disease--a bright future ahead?

Many links are reported or suspected between the functioning of creatine, phosphocreatine, the creatine kinase isoenzymes or the creatine biosynthesis enzymes on one hand, and health or disease on the other hand. The aim of the present book was to outline our current understanding on many of these links. In this chapter, we summarize the main messages and conclusions presented in this book. In addition, we refer to a number of recent publications that highlight the pleiotropy in physiological functions of creatine and creatine kinase, and which suggest that numerous discoveries on new functions of this system are still ahead of us. Finally, we present our views on the most promising future avenues of research to deepen our knowledge on creatine and creatine kinase. In particular, we elaborate on how state-of-the-art high-throughput analytical ("omics") technologies and systems biology approaches may be used successfully to unravel the complex network of interdependent physiological functions related to creatine and creatine kinase.