Glucagon-like peptide 2 stimulates glucagon secretion, enhances lipid absorption, and inhibits gastric acid secretion in humans

DEFF Research Database (Denmark)

Meier, Juris J; Nauck, Michael A; Pott, Andrea

2006-01-01

or placebo during the ingestion of a solid test meal. Gastric emptying was determined using a 13C-sodium-octanote breath test. Plasma concentrations of glucose, insulin, C-peptide, glucagon, GLP-2, free fatty acids, free glycerol, and triglycerides were determined. RESULTS: GLP-2 administration led...... (P = .07). GLP-2 administration caused an approximately 15% reduction in pentagastrin-stimulated gastric acid and chloride secretion (P gastric emptying was not affected (P = .99). CONCLUSIONS: GLP-2 reduces gastric acid secretion but does not seem to have an influence on gastric......BACKGROUND & AIMS: The gut-derived peptide glucagon-like peptide 2 (GLP-2) has been suggested as a potential drug candidate for the treatment of various intestinal diseases. However, the acute effects of GLP-2 on gastric functions as well as on glucose and lipid homeostasis in humans are less well...

Ascorbate attenuates pulmonary emphysema by inhibiting tobacco smoke and Rtp801-triggered lung protein modification and proteolysis.

Science.gov (United States)

Gupta, Indranil; Ganguly, Souradipta; Rozanas, Christine R; Stuehr, Dennis J; Panda, Koustubh

2016-07-19

Cigarette smoking causes emphysema, a fatal disease involving extensive structural and functional damage of the lung. Using a guinea pig model and human lung cells, we show that oxidant(s) present in tobacco smoke not only cause direct oxidative damage of lung proteins, contributing to the major share of lung injury, but also activate Rtp801, a key proinflammatory cellular factor involved in tobacco smoke-induced lung damage. Rtp801 triggers nuclear factor κB and consequent inducible NOS (iNOS)-mediated overproduction of NO, which in combination with excess superoxide produced during Rtp801 activation, contribute to increased oxido-nitrosative stress and lung protein nitration. However, lung-specific inhibition of iNOS with a iNOS-specific inhibitor, N6-(1-iminoethyl)-L-lysine, dihydrochloride (L-NIL) solely restricts lung protein nitration but fails to prevent or reverse the major tobacco smoke-induced oxidative lung injury. In comparison, the dietary antioxidant, ascorbate or vitamin C, can substantially prevent such damage by inhibiting both tobacco smoke-induced lung protein oxidation as well as activation of pulmonary Rtp801 and consequent iNOS/NO-induced nitration of lung proteins, that otherwise lead to increased proteolysis of such oxidized or nitrated proteins by endogenous lung proteases, resulting in emphysematous lung damage. Vitamin C also restricts the up-regulation of matrix-metalloproteinase-9, the major lung protease involved in the proteolysis of such modified lung proteins during tobacco smoke-induced emphysema. Overall, our findings implicate tobacco-smoke oxidant(s) as the primary etiopathogenic factor behind both the noncellular and cellular damage mechanisms governing emphysematous lung injury and demonstrate the potential of vitamin C to accomplish holistic prevention of such damage.

Hypothalamic CaMKKβ mediates glucagon anorectic effect and its diet-induced resistance

Science.gov (United States)

Quiñones, Mar; Al-Massadi, Omar; Gallego, Rosalía; Fernø, Johan; Diéguez, Carlos; López, Miguel; Nogueiras, Ruben

2015-01-01

Objective Glucagon receptor antagonists and humanized glucagon antibodies are currently studied as promising therapies for obesity and type II diabetes. Among its variety of actions, glucagon reduces food intake, but the molecular mechanisms mediating this effect as well as glucagon resistance are totally unknown. Methods Glucagon and adenoviral vectors were administered in specific hypothalamic nuclei of lean and diet-induced obese rats. The expression of neuropeptides controlling food intake was performed by in situ hybridization. The regulation of factors of the glucagon signaling pathway was assessed by western blot. Results The central injection of glucagon decreased feeding through a hypothalamic pathway involving protein kinase A (PKA)/Ca2+-calmodulin-dependent protein kinase kinase β (CaMKKβ)/AMP-activated protein kinase (AMPK)-dependent mechanism. More specifically, the central injection of glucagon increases PKA activity and reduces protein levels of CaMKKβ and its downstream target phosphorylated AMPK in the hypothalamic arcuate nucleus (ARC). Consistently, central glucagon significantly decreased AgRP expression. Inhibition of PKA and genetic activation of AMPK in the ARC blocked glucagon-induced anorexia in lean rats. Genetic down-regulation of glucagon receptors in the ARC stimulates fasting-induced hyperphagia. Although glucagon was unable to decrease food intake in DIO rats, glucagon sensitivity was restored after inactivation of CaMKKβ, specifically in the ARC. Thus, glucagon decreases food intake acutely via PKA/CaMKKβ/AMPK dependent pathways in the ARC, and CaMKKβ mediates its obesity-induced hypothalamic resistance. Conclusions This work reveals the molecular underpinnings by which glucagon controls feeding that may lead to a better understanding of disease states linked to anorexia and cachexia. PMID:26909312

Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

OpenAIRE

Tawa, N E; Odessey, R; Goldberg, A L

1997-01-01

Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.g., MG132 at 10 microM) inhibited nonlyso...

Glucagon blood test

Science.gov (United States)

... page: //medlineplus.gov/ency/article/003716.htm Glucagon blood test To use the sharing features on this page, please enable JavaScript. A glucagon blood test measures the amount of a hormone called glucagon ...

Pathophysiology of glucagon secretion

International Nuclear Information System (INIS)

Boettger, J.; Pabst, H.W.

1980-01-01

Pathophysiology of glucagon secretion is reviewed in brief separating hyperglucagonemic from hypoclucagonemic states. Many questions concerning the role of glucagon in diabetes mellitus and in other diseases are still unresolved. The clucagon RIA is of clinical significance in a few diseases like glucagonoma, which may present without symptoms of the 'glucagonoma syndrome', the probably very rare hyperglucagonemia and some of the spontaneous hypoglycemias. Glucagon secretion may be evaluated by the determination of fasting immunoreactive glucagon (IRG) and by appropriate function tests as stimulation with i.v. arginine and suppression with oral glucose. However, the glucagon RIA at present is not a routine method, although commercial kits are available. Many pitfalls of radioimmunological glucagon determination still exist. (orig.) [de

Modelling the glucose-insulin-glucagon dynamics after subcutaneous administration of native glucagon and a novel glucagon analogue in dogs

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Boye Knudsen, Carsten; Jørgensen, John Bagterp

Zealand Pharma has invented a glucagon analogue, ZP-GA-1, with increased stability in liquid formulation for treatment of hypoglycemia. A pharmacodynamic (PD) model is needed to compare ZP-GA-1 with marketed glucagon. We aim to develop a model of the complex glucose-insulin-glucagon dynamics based...... on physiology and data....

cAMP-dependent proteolysis of GATA-6 is linked to JNK-signaling pathway

Energy Technology Data Exchange (ETDEWEB)

Ushijima, Hironori [Department of Molecular Biology, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Shiwagun, Iwate 028-3694 (Japan); Maeda, Masatomo, E-mail: mmaeda@iwate-med.ac.jp [Department of Molecular Biology, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Shiwagun, Iwate 028-3694 (Japan)

2012-07-13

Highlights: Black-Right-Pointing-Pointer A JNK inhibitor SP600125 inhibited cAMP-dependent proteolysis of GATA-6. Black-Right-Pointing-Pointer Effect of a JNK activator anisomycin on the proteolysis was examined. Black-Right-Pointing-Pointer Anisomycin stimulated the export of nuclear GATA-6 into the cytoplasm. Black-Right-Pointing-Pointer JNK activated the CRM1 mediated nuclear export of GATA-6. Black-Right-Pointing-Pointer JNK further stimulated slowly the degradation of GATA-6 by cytoplasmic proteasomes. -- Abstract: A JNK inhibitor SP600125 inhibited cAMP-dependent proteolysis of GATA-6 by proteasomes around its IC50. We further examined the effects of SP600125 on the degradation of GATA-6 in detail, since an activator of JNK (anisomycin) is available. Interestingly, anisomycin immediately stimulated the export of nuclear GATA-6 into the cytoplasm, and then the cytoplasmic content of GATA-6 decreased slowly through degradation by proteasomes. Such an effect of anisomycin was inhibited by SP600125, indicating that the observed phenomenon might be linked to the JNK signaling pathway. The inhibitory effect of SP600125 could not be ascribed to the inhibition of PKA, since phosphorylation of CREB occurred in the presence of dbcAMP and SP600125. The nuclear export of GATA-6 was inhibited by leptomycin B, suggesting that CRM1-mediated export could be activated by anisomycin. Furthermore, it seems likely that the JNK activated by anisomycin may stimulate not only the nuclear export of GATA-6 through CRM1 but also the degradation of GATA-6 by cytoplasmic proteasomes. In contrast, A-kinase might activate only the latter process through JNK.

Neutrophils Release Metalloproteinases during Adhesion in the Presence of Insulin, but Cathepsin G in the Presence of Glucagon

Directory of Open Access Journals (Sweden)

Natalia V. Fedorova

2018-01-01

Full Text Available In patients with reperfusion after ischemia and early development of diabetes, neutrophils can attach to blood vessel walls and release their aggressive bactericide agents, which damage the vascular walls. Insulin and 17β-estradiol (E2 relieve the vascular complications observed in metabolic disorders. In contrast, glucagon plays an essential role in the pathophysiology of diabetes. We studied the effect of hormones on neutrophil secretion during adhesion to fibronectin. Amino acid analysis revealed that proteins secreted by neutrophils are characterized by a stable amino acid profile enriched with glutamate, leucine, lysine, and arginine. The total amount of secreted proteins defined as the sum of detected amino acids was increased in the presence of insulin and reduced in the presence of glucagon. E2 did not affect the amount of protein secretion. Proteome analysis showed that in the presence of insulin and E2, neutrophils secreted metalloproteinases MMP-9 and MMP-8 playing a key role in modulation of the extracellular matrix. In contrast, glucagon induced the secretion of cathepsin G, a key bactericide protease of neutrophils. Cathepsin G can promote the development of vascular complications because of its proinflammatory activity and ability to stimulate neutrophil adhesion via the proteolysis of surface receptors.

Different domains of the glucagon and glucagon-like peptide-1 receptors provide the critical determinants of ligand selectivity

DEFF Research Database (Denmark)

Runge, S; Wulff, B S; Madsen, K

2003-01-01

analysed chimeric glucagon/GLP-1 peptides for their ability to bind and activate the glucagon receptor, the GLP-1 receptor and chimeric glucagon/GLP-1 receptors. The chimeric peptide GLP-1(7-20)/glucagon(15-29) was unable to bind and activate the glucagon receptor. Substituting the glucagon receptor core......-terminus of chimera A with the corresponding glucagon receptor segments re-established the ability to distinguish GLP-1(7-20)/glucagon(15-29) from glucagon. Corroborant results were obtained with the opposite chimeric peptide glucagon(1-14)/GLP-1(21-37). (3) The results suggest that the glucagon and GLP-1 receptor......(1) Glucagon and glucagon-like peptide-1 (GLP-1) are homologous peptide hormones with important functions in glucose metabolism. The receptors for glucagon and GLP-1 are homologous family B G-protein coupled receptors. The GLP-1 receptor amino-terminal extracellular domain is a major determinant...

Glucagon Couples Hepatic Amino Acid Catabolism to mTOR-Dependent Regulation of α-Cell Mass

Directory of Open Access Journals (Sweden)

Mark J. Solloway

2015-07-01

Full Text Available Understanding the regulation of islet cell mass has important implications for the discovery of regenerative therapies for diabetes. The liver plays a central role in metabolism and the regulation of endocrine cell number, but liver-derived factors that regulate α-cell and β-cell mass remain unidentified. We propose a nutrient-sensing circuit between liver and pancreas in which glucagon-dependent control of hepatic amino acid metabolism regulates α-cell mass. We found that glucagon receptor inhibition reduced hepatic amino acid catabolism, increased serum amino acids, and induced α-cell proliferation in an mTOR-dependent manner. In addition, mTOR inhibition blocked amino-acid-dependent α-cell replication ex vivo and enabled conversion of α-cells into β-like cells in vivo. Serum amino acids and α-cell proliferation were increased in neonatal mice but fell throughout postnatal development in a glucagon-dependent manner. These data reveal that amino acids act as sensors of glucagon signaling and can function as growth factors that increase α-cell proliferation.

Radioimmunoassay of pancreatic glucagon

International Nuclear Information System (INIS)

Nooijen, W.J.

1979-01-01

The author presents some of the problems and concepts related to the development of a radioimmunoassay of pancreatic glucagon. A specific derivatization of glucagon for raising specific anti-glucagon antisera is introduced, and special procedures for diminishing the non-specific effect are outlined. (G.T.H.)

Insulin and Glucagon

DEFF Research Database (Denmark)

Holst, Jens Juul; Holland, William; Gromada, Jesper

2017-01-01

In August 2016, several leaders in glucagon biology gathered for the European Association for the Study of Diabetes Hagedorn Workshop in Oxford, England. A key point of discussion focused on the need for basal insulin to allow for the therapeutic benefit of glucagon blockade in the treatment...... of the discussion as a consensus was reached. Agents that antagonize glucagon may be of great benefit for the treatment of diabetes; however, sufficient levels of basal insulin are required for their therapeutic efficacy....

Effect of glucagon on cyclic AMP, albumin metabolism and incorporation of 14C-leucine into proteins in isolated parenchymal rat liver cells

DEFF Research Database (Denmark)

Dich, J; Gluud, C N

1976-01-01

wet wt. This is about the rate found in the perfused liver, Glucagon (10(-8-10(-6) M) inhibited albumin secretion and the incorporation of 14C-leucine into albumin, into total proteins in the medium and into total proteins in the cell suspension. The effect of glucagon on albumin secretion...... is compatible with an effect on the rate of synthesis. A positive correlation existed between the maximal level of cyclic AMP after glucagon administration and the inhibition of both albumin secretion and the incorporation of 149leucine....

Glucagon for hypoglycemic episodes in insulin-treated diabetic patients: a systematic review and meta-analysis with a comparison of glucagon with dextrose and of different glucagon formulations.

Science.gov (United States)

Boido, Augusto; Ceriani, Valerio; Pontiroli, Antonio E

2015-04-01

Glucagon is used as an emergency drug in hypoglycemia, mainly when the patient is unconscious. A few studies report on ineffectiveness of glucagon in relieving hypoglycemia. The present systematic review and meta-analysis evaluate the effectiveness of glucagon alone and in comparison with dextrose and the effectiveness of intranasal glucagon in comparison with injected glucagon. Studies were grouped into three groups: (1) reports on glucagon ineffectiveness; (2) comparison of glucagon and dextrose; (3) comparison of intranasal glucagon and injected glucagon. In groups 2 and 3, only controlled studies were included in the analysis, whether randomized or non-randomized studies. Appropriate methodology (PRISMA statement) was adhered to, and publication bias was formally assessed. Sixteen studies, published in any language as full papers, were analysed to identify predictors of ineffectiveness, and they were included in a meta-analysis (random effects model) to study the effect of different strategies. Intervention effect (number of failures) was expressed as odds ratio (OR), with 95 % confidence intervals. Failure rate ranged from 0.0 to 2.31 %, to 7.6 %, to 14.4 %, and to 59 %. Comparing glucagon and dextrose, the OR was 0.53 (0.20-1.42); comparing intranasal and intramuscular glucagon, the OR was 1.40 (0.18-10.93). Heterogeneity was low and not statistically significant. Publication bias was absent. These data indicate that ineffectiveness of glucagon is unfrequent, not different from dextrose; in addition, intranasal and injected glucagon are similarly effective. In the case of failure, a second dose can be administered.

Hyperglucagonaemia analysed by glucagon sandwich ELISA

DEFF Research Database (Denmark)

Albrechtsen, Nicolai Jacob Wewer; Hartmann, Bolette; Veedfald, Simon

2014-01-01

the extent to which the hyperglucagonaemia measured in clinical samples was caused by authentic glucagon. METHODS: We examined the performance of three commercial glucagon 'sandwich' ELISAs. The ELISA with the best overall performance was selected to compare glucagon measurements in clinical samples...... sensitivity for glucagon in plasma (>10-20 pmol/l). Thus, only the third assay was suitable for measuring glucagon concentrations in clinical samples. The ELISA and RIA measured similar glucagon levels in healthy individuals. Measurements of samples from individuals with abnormally high (type 2 diabetes...... or obese) or very elevated (post vagotomy with pyloroplasty, post-RYGB) glucagon levels were also similar in both assays. However, glucagon levels in participants with ESRD were much lower when measured by ELISA than by RIA, indicating that the apparent hyperglucagonaemia is not caused by fully processed...

Current Therapies That Modify Glucagon Secretion

DEFF Research Database (Denmark)

Grøndahl, Magnus F.; Keating, Damien J.; Vilsbøll, Tina

2017-01-01

and provide insights into how antidiabetic drugs influence glucagon secretion as well as a perspective on the future of glucagon-targeting drugs. Recent Findings: Several older as well as recent investigations have evaluated the effect of antidiabetic agents on glucagon secretion to understand how glucagon...... may be involved in the drugs’ efficacy and safety profiles. Based on these findings, modulation of glucagon secretion seems to play a hitherto underestimated role in the efficacy and safety of several glucose-lowering drugs. Summary: Numerous drugs currently available to diabetologists are capable...... of altering glucagon secretion: metformin, sulfonylurea compounds, insulin, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors and amylin mimetics. Their diverse effects on glucagon secretion are of importance for their individual efficacy...

Hyperglucagonemia during insulin deficiency accelerates protein catabolism

International Nuclear Information System (INIS)

Nair, K.S.; Halliday, D.; Matthews, D.E.; Welle, S.L.

1987-01-01

Hyperglucagonemia coexists with insulin deficiency or insulin resistance in many conditions where urinary nitrogen excretion is increased, but the precise role of glucagon in these conditions is controversial. The purpose of this study was to evaluate the effect of hyperglucagonemia on protein metabolism in insulin-deficient subjects. The authors used the stable isotope of an essential amino acid (L-[1- 13 C]leucine) as a tracer of in vivo protein metabolism. A combined deficiency of insulin and glucagon was induced by intravenous infusion of somatostatin. Hyperglucagonemia and hypoinsulinemia were induced by infusions of somatostatin and glucagon. When somatostatin alone was infused leucine flux increased, indicating a 6-17% increase in proteolysis. When somatostatin and glucagon were infused, leucine flux increased, indicating a 12-32% increase in proteolysis. The increase in leucine flux during the infusion of somatostatin and glucagon was higher than the increase during infusion of somatostatin alone. Somatostatin alone did not change leucine oxidation, whereas the somatostatin plus glucagon increased leucine oxidation 100%. They conclude that hyperglucagonemia accelerated proteolysis and leucine oxidation in insulin-deficient humans

Stability of glucagon-like peptide-1 and glucagon in human plasma

DEFF Research Database (Denmark)

Albrechtsen, Nicolai Jacob Wewer; Bak, Monika Judyta; Hartmann, Bolette

2015-01-01

or an inhibitor cocktail. GLP-1, but not glucagon, was stable for at least 1 year. Surprisingly, the recovery of glucagon was reduced by almost 50% by freezing compared to immediate analysis, regardless of storage time. Conclusion: Plasma handling procedures can significantly influence results of subsequent...

Homozygous carriers of the G allele of rs4664447 of the glucagon gene (GCG) are characterised by decreased fasting and stimulated levels of insulin, glucagon and glucagon-like peptide (GLP)-1

DEFF Research Database (Denmark)

Torekov, S S; Ma, L; Grarup, N

2011-01-01

The glucagon gene (GCG) encodes several hormones important for energy metabolism: glucagon, oxyntomodulin and glucagon-like peptide (GLP)-1 and -2. Variants in GCG may associate with type 2 diabetes, obesity and/or related metabolic traits.......The glucagon gene (GCG) encodes several hormones important for energy metabolism: glucagon, oxyntomodulin and glucagon-like peptide (GLP)-1 and -2. Variants in GCG may associate with type 2 diabetes, obesity and/or related metabolic traits....

Glucose decouples intracellular Ca2+ activity from glucagon secretion in mouse pancreatic islet alpha-cells.

Directory of Open Access Journals (Sweden)

Sylvain J Le Marchand

Full Text Available The mechanisms of glucagon secretion and its suppression by glucose are presently unknown. This study investigates the relationship between intracellular calcium levels ([Ca(2+](i and hormone secretion under low and high glucose conditions. We examined the effects of modulating ion channel activities on [Ca(2+](i and hormone secretion from ex vivo mouse pancreatic islets. Glucagon-secreting α-cells were unambiguously identified by cell specific expression of fluorescent proteins. We found that activation of L-type voltage-gated calcium channels is critical for α-cell calcium oscillations and glucagon secretion at low glucose levels. Calcium channel activation depends on K(ATP channel activity but not on tetrodotoxin-sensitive Na(+ channels. The use of glucagon secretagogues reveals a positive correlation between α-cell [Ca(2+](i and secretion at low glucose levels. Glucose elevation suppresses glucagon secretion even after treatment with secretagogues. Importantly, this inhibition is not mediated by K(ATP channel activity or reduction in α-cell [Ca(2+](i. Our results demonstrate that glucose uncouples the positive relationship between [Ca(2+](i and secretory activity. We conclude that glucose suppression of glucagon secretion is not mediated by inactivation of calcium channels, but instead, it requires a calcium-independent inhibitory pathway.

Peptidomics for Studying Limited Proteolysis.

Science.gov (United States)

Tsuchiya, Takashi; Osaki, Tsukasa; Minamino, Naoto; Sasaki, Kazuki

2015-11-06

Limited proteolysis is a pivotal mechanism regulating protein functions. Identifying physiologically or pathophysiologically relevant cleavage sites helps to develop molecular tools that can be used for diagnostics or therapeutics. During proteolysis of secretory and membrane proteins, part of the cleaved protein is liberated and destined to undergo degradation but should retain original cleavage sites created by proteolytic enzymes. We profiled endogenous peptides accumulated for 4 h in media conditioned by primary cultured rat cardiac fibroblasts. A total of 3916 redundant peptide sequences from 94 secretory proteins and membrane proteins served to identify limited cleavage sites, both annotated and unannotated, for signal peptide or propeptide removal, peptide hormone processing, ectodomain shedding, and regulated intramembrane proteolysis. Incorrectly predicted signal cleavage sites are found in typical proteins such as extracellular matrix proteins and the peptide hormone precursor adrenomedullin ADM. The revealed signal peptide cleavage site for ADM was experimentally verified by identifying the major molecular form of flanking proadrenomedullin N-terminal peptide. We suggest that profiling of endogenous peptides, like transcriptome sequence reads, makes sense in regular cells such as fibroblasts and that peptidomics provides insight into proteolysis-regulated protein functions.

Glucagon and glucagon-like peptides 1 and 2

DEFF Research Database (Denmark)

Holst, Jens Juul

2010-01-01

amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78....... After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than...

Three distinct epitopes on the extracellular face of the glucagon receptor determine specificity for the glucagon amino terminus

DEFF Research Database (Denmark)

Runge, Steffen; Gram, Christian; Bräuner-Osborne, Hans

2003-01-01

. Only 4 of 15 residues are divergent in the glucagon and GLP-1 amino termini; Ser2, Gln3, Tyr10, and Lys12 in glucagon and the corresponding Ala8, Glu9, Val16, and Ser18 in GLP-1. In this study, individual substitution of these four residues of glucagon with the corresponding residues of GLP-1 decreased...... are close to and determine specificity for Gln3 and Ser2 of glucagon, respectively. Furthermore, the second extracellular loop and/or proximal segments of TM4 and/or TM5 are close to and determine specificity for Lys12 of glucagon....

Functional Imaging of Proteolysis: Stromal and Inflammatory Cells Increase Tumor Proteolysis

Directory of Open Access Journals (Sweden)

Mansoureh Sameni

2003-07-01

Full Text Available The underlying basement membrane is degraded during progression of breast and colon carcinoma. Thus, we imaged degradation of a quenched fluorescent derivative of basement membrane type IV collagen (DQ-collagen IV by living human breast and colon tumor spheroids. Proteolysis of DQ-collagen IV by HCT 116 and HKh-2 human colon tumor spheroids was both intracellular and pericellular. In contrast, proteolysis of DQ-collagen IV by BT20 human breast tumor spheroids was pericellular. As stromal elements can contribute to proteolytic activities associated with tumors, we also examined degradation of DQ-collagen IV by human monocytes/macrophages and colon and breast fibroblasts. Fibroblasts themselves exhibited a modest amount of pericellular degradation. Degradation was increased 4–17-fold in cocultures of fibroblasts and tumor cells as compared to either cell type alone. Inhibitors of matrix metalloproteinases, plasmin, and the cysteine protease, cathepsin B, all reduced degradation in the cocultures. Monocytes did not degrade DQ-collagen IV; however, macrophages degraded DQ-collagen IV intracellularly. In coculture of tumor cells, fibroblasts, and macrophages, degradation of DQ-collagen IV was further increased. Imaging of living tumor and stromal cells has, thus, allowed us to establish that tumor proteolysis occurs pericellularly and intracellularly and that tumor, stromal, and inflammatory cells all contribute to degradative processes.

Determination of Glucagon-Like Peptide-1, Glucagon and Oxyntomodulin in Plasma

DEFF Research Database (Denmark)

Bak, Monika Judyta

Glucagon-like peptide-1, glucagon and oxyntomodulin are three peptide hormones which play a significant role in diabetes, however there is a major controversy regarding their exact roles due to difficulties in measuring of these peptides because of molecular heterogeneity, low circulating concent...... of the studies from the literature that have provided reliable measurements and thereby help resolve controversies regarding the metabolic roles of the peptides. The improved technology should also provide better reliability of future publications in the field......., the addition of aprotinin to plasma prior to glucagon sample analysis was investigated. Aprotinin addition has been recommended for many years to avoid peptide degradation during sampling and storage. To make sure that the analysed samples are handled correctly and that the peptides are not degraded, a study...

Decreased hepatic response to glucagon, adrenergic agonists, and cAMP in glycogenolysis, gluconeogenesis, and glycolysis in tumor-bearing rats.

Science.gov (United States)

Biazi, Giuliana R; Frasson, Isabele G; Miksza, Daniele R; de Morais, Hely; de Fatima Silva, Flaviane; Bertolini, Gisele L; de Souza, Helenir M

2018-05-15

The response to glucagon and adrenaline in cancer cachexia is poorly known. The aim of this study was to investigate the response to glucagon, adrenergic agonists (α and β) and cyclic adenosine monophosphate (cAMP) on glycogenolysis, gluconeogenesis, and glycolysis in liver perfusion of Walker-256 tumor-bearing rats with advanced cachexia. Liver ATP content was also investigated. Rats without tumor (healthy) were used as controls. Agonists α (phenylephrine) and β (isoproterenol) adrenergic, instead of adrenaline, and cAMP, the second messenger of glucagon and isoproterenol, were used in an attempt to identify mechanisms involved in the responses. Glucagon (1 nM) stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis in the liver of healthy and tumor-bearing rats, but their effects were lower in tumor-bearing rats. Isoproterenol (20 µM) stimulated glycogenolysis, gluconeogenesis, and glycolysis in healthy rats and had virtually no effect in tumor-bearing rats. cAMP (9 µM) also stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis in healthy rats but had practically no effect in tumor-bearing rats. Phenylephrine (2 µM) stimulated glycogenolysis and gluconeogenesis and inhibited glycolysis and these effects were also lower in tumor-bearing rats than in healthy. Liver ATP content was lower in tumor-bearing rats. In conclusion, tumor-bearing rats with advanced cachexia showed a decreased hepatic response to glucagon, adrenergic agonists (α and β), and cAMP in glycogenolysis, gluconeogenesis, and glycolysis, which may be due to a reduced rate of regulatory enzyme phosphorylation caused by the low ATP levels in the liver. © 2018 Wiley Periodicals, Inc.

Glucagon and type 2 diabetes

DEFF Research Database (Denmark)

Lund, Asger; Bagger, Jonatan I; Christensen, Mikkel

2014-01-01

In normal physiology, glucagon from pancreatic alpha cells plays an important role in maintaining glucose homeostasis via its regulatory effect on hepatic glucose production. Patients with type 2 diabetes suffer from fasting and postprandial hyperglucagonemia, which stimulate hepatic glucose...... production and, thus, contribute to the hyperglycemia characterizing these patients. Although this has been known for years, research focusing on alpha cell (patho)physiology has historically been dwarfed by research on beta cells and insulin. Today the mechanisms behind type 2 diabetic hyperglucagonemia...... or antagonization of the glucagon receptor constitutes potentially effective treatment strategies for patients with type 2 diabetes. In this review, we focus on the regulation of glucagon secretion by the incretin hormones glucagon-like peptide-1 (GLP-1) and GIP. Furthermore, potential advantages and limitations...

Model of the Glucose-Insulin-Glucagon Dynamics after Subcutaneous Administration of a Glucagon Rescue Bolus in Healthy Humans

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Møller, Jan Kloppenborg; Haidar, Ahmad

In healthy individuals, insulin and glucagon work in a complex fashion to maintain blood glucose levels within a narrow range. This regulation is distorted in patients with diabetes. The hepatic glucose response due to an elevated glucagon level depends on the current insulin concentration and thus...... endogenous glucose production (EGP) can not be modelled without knowledge of the concentration of both hormones in plasma. Furthermore, literature suggests an upper limit to EGP irrespective of glucagon levels. We build a simulation model of the glucose-insulin-glucagon dynamics in man including saturation...... effect of EGP. Ten healthy subjects received a 1 mg subcutaneous (SC) glucagon bolus (GlucaGen®). Plasma samples were collected until 300 minutes post dose and analyzed for glucagon, insulin, and glucose concentrations. All observations were used to fit a physiological model of the glucose...

The alpha cell expresses glucagon-like peptide-2 receptors and glucagon-like peptide-2 stimulates glucagon secretion from the rat pancreas

DEFF Research Database (Denmark)

de Heer, J; Pedersen, J; Orskov, C

2007-01-01

AIMS/HYPOTHESIS: Glucagon-like peptide-2 (GLP-2) is a gut hormone regulating intestinal growth and nutrient absorption. Recently, GLP-2 has been reported to stimulate glucagon secretion in healthy humans. We sought to clarify the mechanism and physiological significance of this endocrine effect. ...... of the glucagonotropic action of GLP-2 in humans....

Anti-glucagon antibodies in diabetes mellitus

Energy Technology Data Exchange (ETDEWEB)

Gergely, A; Koranyi, L; Halmos, T; Zsombok, M; Peterfy, F; Csizer, Z; Salamon, F; Tako, J

1973-01-01

Anti-insulin antibodies appear in the sera of patients treated with insulin lastingly. A high anti-insulin antibody level results in the development of insulin resistance. Most of the insulin preparations available on the market contain also glucagon as an impurity. It was therefore to be expected that in part of the patients, who had been treated with insulin lastingly, antibodies would be produced also against glucagon, and the presence of these was actually demonstrated. It is to be assumed that the anti-glucagon antibodies play a role in the pathomechanism of diabetes mellitus, mainly in its labile form. The possible presence of anti-glucagon antibodies must be taken into account when the glucagon concentration in the sera of diabetics is to be determined by means of radioimmunoassay (RIA). The specific antibodies in the serum give false results in the quantitative determination of glucagon. We have tested the sera of 10 diabetics who had been treated with insulin for at least 6 years. All patients were given protamine zinc and crystalline insulin preparations.

Ca2+ dependence of gluconeogenesis stimulation by glucagon at different cytosolic NAD+-NADH redox potentials

Directory of Open Access Journals (Sweden)

Marques-da-Silva A.C.

1997-01-01

Full Text Available The influence of Ca2+ on hepatic gluconeogenesis was measured in the isolated perfused rat liver at different cytosolic NAD+-NADH potentials. Lactate and pyruvate were the gluconeogenic substrates and the cytosolic NAD+-NADH potentials were changed by varying the lactate to pyruvate ratios from 0.01 to 100. The following results were obtained: a gluconeogenesis from lactate plus pyruvate was not affected by Ca2+-free perfusion (no Ca2+ in the perfusion fluid combined with previous depletion of the intracellular pools; gluconeogenesis was also poorly dependent on the lactate to pyruvate ratios in the range of 0.1 to 100; only for a ratio equal to 0.01 was a significantly smaller gluconeogenic activity observed in comparison to the other ratios. b In the presence of Ca2+, the increase in oxygen uptake caused by the infusion of lactate plus pyruvate at a ratio equal to 10 was the most pronounced one; in Ca2+-free perfusion the increase in oxygen uptake caused by lactate plus pyruvate infusion tended to be higher for all lactate to pyruvate ratios; the most pronounced difference was observed for a lactate/pyruvate ratio equal to 1. c In the presence of Ca2+ the effects of glucagon on gluconeogenesis showed a positive correlation with the lactate to pyruvate ratios; for a ratio equal to 0.01 no stimulation occurred, but in the 0.1 to 100 range stimulation increased progressively, producing a clear parabolic dependence between the effects of glucagon and the lactate to pyruvate ratio. d In the absence of Ca2+ the relationship between the changes caused by glucagon in gluconeogenesis and the lactate to pyruvate ratio was substantially changed; the dependence curve was no longer parabolic but sigmoidal in shape with a plateau beginning at a lactate/pyruvate ratio equal to 1; there was inhibition at the lactate to pyruvate ratios of 0.01 and 0.1 and a constant stimulation starting with a ratio equal to 1; for the lactate to pyruvate ratios of 10 and 100

Excess alpha chains are lost from beta-thalassemic reticulocytes by proteolysis

International Nuclear Information System (INIS)

Testa, U.; Hinard, N.; Beuzard, Y.; Tsapis, A.; Galacteros, F.; Thomopoulos, P.; Rosa, J.

1981-01-01

During incubation of reticulocytes from patients with beta-thalassemia, after labeling of the hemoglobin with radioactive amino acids, the excess alpha chains are gradually lost from the cells. The aim of this study was to investigate the mechanism of this phenomenon. A system was developed in which reticulocytes from beta-thalassemia patients are labeled with [3H]leucine, washed several times in nonradioactive medium, and then incubated in the same medium containing puromycin added in order to stop further protein synthesis. The results have clearly shown that excess alpha chains are gradually degraded by proteolysis. N-ethylmaleimide or epsilon-aminocaproic acid inhibited the proteolysis of free alpha chains. The addition of either ATP or hemin did not change the rate of alpha chain degradation. The time required to degrade 50% of the pool of free alpha chains was directly dependent on the initial value of this pool. This finding suggests the absence of a significant individual variation in the ability to proteolyse free alpha chains

Hemodynamic Effects of Glucagon - A Literature Review

DEFF Research Database (Denmark)

Meidahl Petersen, Kasper; Bøgevig, Søren; Holst, Jens Juul

2018-01-01

Context: Glucagon's effects on hemodynamic parameters - most notably heart rate and cardiac contractility - are overlooked. The glucagon receptor is a central target in novel and anticipated type 2 diabetes therapies and hemodynamic consequences of glucagon signaling have therefore become increas...

Radioimmunoassay of pancreatic glucagon. Improvement of method and application in order to determine the role of glucagon in the polytrauma

International Nuclear Information System (INIS)

Schrezenmeir, J.

1980-01-01

Radio-iodizing of glucagon under the application of chloralamine-T was examined and optimized with respect to its dependency on the concentration of the reacting agents, on the duration of reaction and on the pH value. The methods of other authors to purify labeled glucagon were put in contrast with the considerably faster and less complicated batch-procedure, in which Ouso G32 is applied. In order to improve the immunogenity of the weak antigen glucagon, different immunogenic preparations were produced and compared with each other. By the glucagon polymerisation with carbodiimid in guadinin HCl-solution, antibodies of excellent quality were obtained. With the glucagon polymers for the first time an immunogen was found, which produced exclusively so-called specific anti-glucagon sera. The influence of the albumine concentration and of the charcoal quantity on the separation of free and antibody-bound glucagon by means of dextran-covered charcoal was investigated. The early beginning of the investigations, the observation of the course, the temporal correlation of numerous other parameters and the fast application of shock-measures led to new knowledge about glucagon in the polytrauma. (orig./MG) [de

Effects of the pesticide amitraz and its metabolite BTS 27271 on insulin and glucagon secretion from the perfused rat pancreas: involvement of alpha2D-adrenergic receptors.

Science.gov (United States)

Abu-Basha, E A; Yibchok-Anun, S; Hopper, D L; Hsu, W H

1999-11-01

The study purpose was to investigate the direct effect of amitraz, a formamidine insecticide/acaricide, and its active metabolite BTS 27271 on insulin and glucagon secretion from the perfused rat pancreas. Amitraz and BTS 27271 (0.01, 0.1, 1, and 10 micromol/L) inhibited insulin secretion in a concentration-dependent manner. Amitraz increased glucagon secretion at 10 micromol/L, whereas BTS 27271 increased glucagon secretion at 1 and 10 micromol/L. Amitraz- and BTS 27271-induced decreases in insulin secretion and increases in glucagon secretion were not abolished during the 10-minute washout period. During the arginine treatment, both amitraz and BTS 27271 groups (0.1, 1, and 10 micromol/L) had lower insulin secretion and higher glucagon secretion than the control group. Idazoxan, an alpha2A/2D-adrenergic receptor (AR) antagonist, prevented the inhibitory effect of amitraz on insulin secretion in a concentration-dependent manner, but prazosin, an alpha1- and alpha2B/2C-AR antagonist, failed to antagonize the effect of amitraz. These results demonstrate that (1) amitraz and BTS 27271 inhibit insulin and stimulate glucagon secretion from the perfused rat pancreas, (2) amitraz inhibits insulin secretion by activation of alpha2D-ARs, since rats have alpha2D- but not alpha2A-ARs, and (3) amitraz and BTS 27271 may have a high binding affinity to the alpha2D-ARs of pancreatic islets.

GLP-1 (glucagon-like peptide 1) and truncated GLP-1, fragments of human proglucagon, inhibit gastric acid secretion in humans

DEFF Research Database (Denmark)

Schjoldager, B T; Mortensen, P E; Christiansen, J

1989-01-01

Glucagon-like peptide 1 amide (GLP-1 amide), a predicted product of the glucagon gene (proglucagon 72-107-amide), and truncated GLP-1 (proglucagon 78-107-amide), recently isolated from porcine small intestine, were infused in doses of 100 and 400 ng/kg/hr and 12.5 and 50 ng/kg/hr, respectively...

Glucagon-like peptide-1 (GLP-1) receptor agonism or DPP-4 inhibition does not accelerate neoplasia in carcinogen treated mice

DEFF Research Database (Denmark)

Kissow, Hannelouise; Hartmann, Bolette; Holst, Jens Juul

2012-01-01

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are secreted in parallel from the intestinal endocrine cells after nutrient intake. GLP-1 is an incretin hormone and analogues are available for the treatment of type 2 diabetes mellitus (T2DM). GLP-2 is an intestinal growth horm...

Glucose recovery after intranasal glucagon during hypoglycaemia in man

DEFF Research Database (Denmark)

Hvidberg, A; Djurup, R; Hilsted, J

1994-01-01

to exceed 3 mmol.l-1 was significantly shorter for i.m. glucagon. The mean plasma glucagon level increased faster after i.m. glucagon than after intranasal glucagon, and the levels remained higher throughout the study period. We conclude that glucose recovery was significantly better after i...... endogenous glucose counterregulation, and glucose turnover was estimated by a 3-[3H]-glucose infusion. When hypoglycaemia was reached, the subjects received either i.m. glucagon of pancreatic extraction (1 mg) or intranasal genetically engineered glucagon (2 mg). The incremental values for plasma glucose...... concentrations 15 min after intranasal and i.m. administration of glucagon differed marginally. However, after 5 min the glucose appearance rate, as well as the incremental values for plasma glucose, were significantly higher for the i.m. glucagon treatment. The mean time taken for incremental plasma glucose...

Glucagon-like peptide 2 inhibits ghrelin secretion in humans

DEFF Research Database (Denmark)

Banasch, Matthias; Bulut, Kerem; Hagemann, Dirk

2006-01-01

INTRODUCTION: The growth hormone secretagogue receptor ligand ghrelin is known to play a pivotal role in the central nervous control of energy homeostasis. Circulating ghrelin levels are high under fasting conditions and decline after meal ingestion, but the mechanisms underlying the postprandial...... drop in ghrelin levels are poorly understood. In the present study we addressed, whether (1) exogenous GLP-2 administration decreases ghrelin levels and (2) what other endogenous factors are related to ghrelin secretion under fasting conditions. PATIENTS AND METHODS: Fifteen healthy male volunteers...... were studied with the intravenous infusion of GLP-2 (2 pmol l(-1) min(-1)) or placebo over 120 min in the fasting state. Plasma concentrations of glucose, insulin, C-peptide, glucagon, intact GLP-2 and ghrelin were determined. RESULTS: During the infusion of GLP-2, plasma concentrations of intact GLP-2...

Plasma glucagon responses to L-arginine in various diseases

International Nuclear Information System (INIS)

Morita, Nobuto; Hayakawa, Hiroyuki; Kawai, Kohzo; Noto, Yutaka; Ohno, Taro

1978-01-01

To clarify the mechanism of abnormal glucose metabolism in the secondary diabetes, we examined the dynamics of plasma glucagon levels in various diseases which may accompany glucose intolerance. Plasma glucagon responses to L-arginine were observed in 20 liver cirrhotics, 8 patients with chronic renal failure, 6 patients with chronic pancreatitis, 4 patients, with hyperthyroidism, 22 diabetics and 9 normal controls. Plasma glucagon levels were determined by the radioimmunoassay method of Unger using 125 I-glucagon and antiserum 30K which is specific for pancreatic glucagon. In the cirrhotics, the plasma glucagon responses to L-arginine were significantly higher than in normal controls. The patients whose BSP retention at 45 minutes were above 30% showed higher plasma glucagon responses than in the patients whose BSP retention at 45 minutes were below 30%, suggesting that the more severely the liver was damaged, the more the plasma glucagon levels were elevated. In the patients with chronic renal failure, the plasma glucagon responses to L-arginine were also significantly higher than in normal controls. These abnormal levels were not improved by a hemodialysis, although serum creatinine levels were fairly decreased. In the patients with chronic pancreatitis, the plasma glucagon responses to L-arginine were the same as those in normal controls. In the patients with hyperthyroidism the plasma glucagon responses to L-arginine seemed to be lower than normal controls. In the diabetics, the plasma glucagon responses to L-arginine were almost the same as in normal controls. However their glucagon levels seemed to be relatively high, considering the fact that diabetics had high blood glucose levels. (auth.)

Studies on the radio-immunological measurement of plasma glucagon

International Nuclear Information System (INIS)

Fessler, J.

1983-01-01

This thesis was intended to study the question whether or not and to what extent it is possible to set up a two-site assay with an antibody directed aqainst N-terminal glucagon and against C-terminal glucagon in order to specifically detect glucagon 1-29. To this end, TPCK-trypsin digestion was used to produce the glucagon fragments 1-12 and 19-29 which were isolated and purified. Glucagon 1-12 was nonspecifically linked to the bifunctional reagent difluorodinitrobenzene; glucagon 19-29 was linked, on the one hand, specifically via its N-terminal aminoacid alanine 19 to bovine serum albumin (BSA) using the novel method by D. Saunders, and, on the other hand, nonspecifically to thyreoglobulin by means of diffluorodinitro benzene. Guinea pigs were immunized with glucagon 1-12-thyreoglobulin and rabbits with glucagon 19-29-BSA and glucagon 19-29-thyreoglobulin. The rabbits only showed antibody titres sufficient for making an RIA with the highest titre being achieved by an antigen produced by means of the Saunders' method. The rabbit antibodies did react with the 125J glucagon tracer; however, the tracer was not displaced from its link to the antibody by an addition of a glucagon 1-29 standard up to 2,000 pg/ml. There is no explanation of this phenomenon to-date. (orig./MG) [de

Involvement of steatosis-induced glucagon resistance in hyperglucagonaemia

DEFF Research Database (Denmark)

Suppli, Malte P; Lund, Asger; Bagger, Jonatan I

2016-01-01

diabetes per se - is the main driver behind fasting hyperglucagonaemia. We hypothesise that in the majority of type 2 diabetic individuals hepatic sensitivity to glucagon is compromised due to hepatic steatosis, and that this provides a feedback mechanism acting at the level of pancreatic alpha cells...... recognised to play a significant role in type 2 diabetic pathophysiology. However, the mechanisms underlying disturbances in the regulation of glucagon remain unclear. Glucagon constitutes the primary stimulus for hepatic glucose production and, thus, upholds adequate blood glucose levels during fasting......, leading to elevated levels of glucagon. Here we present our hypothesis and propose a way to test it. If our hypothesis holds true, hepatic glucagon resistance would constitute a parallel to the obesity-induced insulin resistance in muscle and liver tissue, and underpin a central role for glucagon...

Radioimmunoassay of extracted glucagon compared with three non-extraction assays

International Nuclear Information System (INIS)

Schenck, H. von; Nilsson, O.R.

1981-01-01

Radioimmunoassay of glucagon was performed with three different antisera, i.e. E7, 30K and 4305, all directed against the carboxyl-terminal region of glucagon and thus avoiding co-determination of glucagon-like polypeptides from the gut. Plasma samples from five healthy people subjected to various A-cell stimulation and suppression tests were used and immunoreactive glucagon assessed with the three antisera. Aliquots from all plasma samples were also extracted with acetone and glucagon re-assessed with antiserum E7. Even though all four baseline glucagon concentrations obtained were different, the glucagon profiles were comparable after superimposing the baselines. The differences in baseline concentrations of immunoreactive glucagon seem due to the interference of 'big plasma glucagon', a still unidentified factor in the E7 and 30K assays that can be precipitated by acetone. Since acetone extraction yielded the lowest baselines without altering the glucagon profiles, it is suggsted that the baseline glucagon concentrations of acetone-extracted plasma reflect the physiological level of the biologically active hormone. Using antiserum E7, our own antiserum, the normal range of glucagon values in acetone-extracted plasma samples from 22 healthy, fasting people of both sexes was 42+-16 ng/l (mean +- 2 S.D.). These values agree well with those obtained by other assay techniques. (Auth.)

The effect of glucagon on infusion cholangiography

International Nuclear Information System (INIS)

Evans, A.F.; Whitehouse, G.H.

1979-01-01

An assessment has been made of the effects of glucagon on biliary tract opacification during intravenous cholangiography. Two series of infusion cholangiograms were obtained at two investigating centres designated A and B. In series A, 41 patients had ioglycamide infusions at a rate of 0.2833 g min -1 over 1 h. In series B, 31 patients had ioglycamide infusions at a rate of 0.3886 g min -1 over 30 min. Radiographs were taken in both series immediately at the end of the infusion, 10 min later and 30 min after the infusion. Two mg of intravenous glucagon was injected into alternate cases in both series A and B immediately after the first radiograph was taken at the completion of the ioglycamide infusion. Two observers in each series then assessed the radiographic opacification of the biliary system without prior knowledge of which patients had received the glucagon. Delineation of the biliary system was considered better in both series in those patients who received glucagon when compared with the controls. Gallbladder opacification was definitely increased in series A in those receiving glucagon, and a similar tendency was shown in series B. The amount of contrast in the upper intestine was increased in series A in the glucagon group, but not in series B. It is concluded that glucagon improves visualisation of the biliary tract, especially the gallbladder at infusion cholangiography. (author)

Effects of dietary biotin supplementation on glucagon production, secretion, and action.

Science.gov (United States)

Lazo-de-la-Vega-Monroy, Maria-Luisa; Larrieta, Elena; Tixi-Verdugo, Wilma; Ramírez-Mondragón, Rafael; Hernández-Araiza, Ileana; German, Michael S; Fernandez-Mejia, Cristina

Despite increasing evidence that pharmacologic concentrations of biotin modify glucose metabolism, to our knowledge there have not been any studies addressing the effects of biotin supplementation on glucagon production and secretion, considering glucagon is one of the major hormones in maintaining glucose homeostasis. The aim of this study was to investigate the effects of dietary biotin supplementation on glucagon expression, secretion, and action. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet (1.76 or 97.7 mg biotin/kg diet) for 8 wk postweaning. Glucagon gene mRNA expression was measured by the real-time polymerase chain reaction. Glucagon secretion was assessed in isolated islets and by glucagon concentration in plasma. Glucagon action was evaluated by glucagon tolerance tests, phosphoenolpyruvate carboxykinase (Pck1) mRNA expression, and glycogen degradation. Compared with the control group, glucagon mRNA and secretion were increased from the islets of the biotin-supplemented group. Fasting plasma glucagon levels were higher, but no differences between the groups were observed in nonfasting glucagon levels. Despite the elevated fasting glucagon levels, no differences were found in fasting blood glucose concentrations, fasting/fasting-refeeding glucagon tolerance tests, glycogen content and degradation, or mRNA expression of the hepatic gluconeogenic rate-limiting enzyme, Pck1. These results demonstrated that dietary biotin supplementation increased glucagon expression and secretion without affecting fasting blood glucose concentrations or glucagon tolerance and provided new insights into the effect of biotin supplementation on glucagon production and action. Copyright © 2017 Elsevier Inc. All rights reserved.

The biology of glucagon and the consequences of hyperglucagonemia

OpenAIRE

Wewer Albrechtsen, Nicolai J; Kuhre, Rune E; Pedersen, Jens; Knop, Filip K; Holst, Jens J

2016-01-01

The proglucagon-derived peptide hormone, glucagon, comprises 29 amino acids. Its secretion from the pancreatic α cells is regulated by several factors. Glucagon increases blood glucose levels through gluconeogenesis and glycogenolysis. Elevated plasma concentrations of glucagon, hyperglucagonemia, may contribute to diabetes. However, hyperglucagonemia is also observed in other clinical conditions than diabetes, including nonalcoholic fatty liver disease, glucagon-producing tumors and after ga...

Evidence of Extrapancreatic Glucagon Secretion in Man

DEFF Research Database (Denmark)

Lund, Asger; Bagger, Jonatan I; Wewer Albrechtsen, Nicolai J

2016-01-01

. We applied novel analytical methods of plasma glucagon (sandwich enzyme-linked immunosorbent assay and mass-spectrometry-based proteomics) and show that 29-amino acid glucagon circulates in patients without a pancreas and that glucose stimulation of the gastrointestinal tract elicits significant......Glucagon is believed to be a pancreas-specific hormone and hyperglucagonemia has been shown to contribute significantly to the hyperglycemic state of patients with diabetes. This hyperglucagonemia has been thought to arise from alpha cell insensitivity to suppressive effects of glucose and insulin...... hyperglucagonemia in these patients. These findings emphasize the existence of extrapancreatic glucagon (perhaps originating from the gut) in man and suggest that it may play a role in diabetes secondary to total pancreatectomy....

Mathematical Modelling of Glucose-Dependent Insulinotropic Polypeptide and Glucagon-like Peptide-1 following Ingestion of Glucose

DEFF Research Database (Denmark)

Røge, Rikke M; Bagger, Jonatan I; Alskär, Oskar

2017-01-01

The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), play an important role in glucose homeostasis by potentiating glucose-induced insulin secretion. Furthermore, GLP-1 has been reported to play a role in glucose homeostasis by inhibiting ...

Study on the Diurnal Variation of the Plasma Immunoreactive Glucagon

International Nuclear Information System (INIS)

Lee, Hong Kyu; Hong, Kee Suk; Kim, Byoung Kook; Koh, Chang Soon; Chung, June Key; Kim, Eui Chong

1984-01-01

It is well known that glucagon, like insulin, is very important in the moment-to-moment control of the homeostasis of glucose, and of amino acids. Glucagon has been shown to have potent glycogenolytic, gluconeogenic and lipolytic activities. Attention to its role in the pathogenesis of diabetes mellitus and hypoglycemia has been also advanced recently. To evaluate the diurnal variation of plasma glucagon concentration, we measured serum glucose, insulin, and plasma glucagon every 30 minutes or every hour in 7 normal Korean adults. Results were as follows: 1) Although plasma glucagon concentration showed wide individual variations, it had a tendency to decrease after meals. After lunch and dinner, plasma glucagon concentration had gradually declined and reached its nadir at postprandial 2-2.5 hours. The minimal level of plasma glucagon was at 4 A.M. 2) Serum insulin:plasma glucagon ratios were increased promptly after meals. Especially after lunch, its peak was prominent (3.65 ± 1. 95). The minimal level of serum insulin:plasma glucagon ratio appeared at 6 A.M.

Study on the Diurnal Variation of the Plasma Immunoreactive Glucagon

Energy Technology Data Exchange (ETDEWEB)

Lee, Hong Kyu; Hong, Kee Suk; Kim, Byoung Kook; Koh, Chang Soon [Seoul National University College of Medicine, Seoul (Korea, Republic of); Chung, June Key; Kim, Eui Chong [Seoul District Armed Forces General Hospital, Seoul (Korea, Republic of)

1984-03-15

It is well known that glucagon, like insulin, is very important in the moment-to-moment control of the homeostasis of glucose, and of amino acids. Glucagon has been shown to have potent glycogenolytic, gluconeogenic and lipolytic activities. Attention to its role in the pathogenesis of diabetes mellitus and hypoglycemia has been also advanced recently. To evaluate the diurnal variation of plasma glucagon concentration, we measured serum glucose, insulin, and plasma glucagon every 30 minutes or every hour in 7 normal Korean adults. Results were as follows: 1) Although plasma glucagon concentration showed wide individual variations, it had a tendency to decrease after meals. After lunch and dinner, plasma glucagon concentration had gradually declined and reached its nadir at postprandial 2-2.5 hours. The minimal level of plasma glucagon was at 4 A.M. 2) Serum insulin:plasma glucagon ratios were increased promptly after meals. Especially after lunch, its peak was prominent (3.65 +- 1. 95). The minimal level of serum insulin:plasma glucagon ratio appeared at 6 A.M.

A first‐in‐human pharmacodynamic and pharmacokinetic study of a fully human anti‐glucagon receptor monoclonal antibody in normal healthy volunteers

Science.gov (United States)

Kostic, Ana; King, Thomas Alexander; Yang, Feng; Chan, Kuo‐Chen; Yancopoulos, George D.; Gromada, Jesper

2017-01-01

Aims Glucagon receptor (GCGR) blockers are being investigated as potential therapeutics for type 1 and type 2 diabetes. Here we report the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of REGN1193, a fully human glucagon receptor blocking monoclonal antibody from a first‐in‐human healthy volunteer randomized double‐blinded trial. Methods Healthy men and women received single ascending doses of REGN1193 ranging from 0.05 to 0.6 mg/kg (n = 42) or placebo (n = 14) intravenously. Safety, tolerability and PK were assessed over 106 days. The glucose‐lowering effect of REGN1193 was assessed after induction of hyperglycaemia by serial glucagon challenges. Results REGN1193 was generally well tolerated. There were small (50 mg/dL, and did not require treatment or medical assistance. Concentration‐time profiles suggest a 2‐compartment disposition and marked nonlinearity, consistent with target‐mediated clearance. REGN1193 inhibited the glucagon‐stimulated glucose increase in a dose‐dependent manner. The 0.6 mg/kg dose inhibited the glucagon‐induced glucose area under the curve for 0 to 90 minutes (AUC0‐90 minutes) by 80% to 90% on days 3 and 15, while blunting the increase in C‐peptide. REGN1193 dose‐dependently increased total GLP‐1, GLP‐2 and glucagon, with plasma levels returning to baseline by day 29 in all dose groups. Conclusion REGN1193, a GCGR‐blocking monoclonal antibody, produced a safety, tolerability and PK/PD profile suitable for further clinical development. The occurrence of transient elevations in serum hepatic aminotransferases observed here and reported with several small molecule glucagon receptor antagonists suggests an on‐target effect of glucagon receptor blockade. The underlying mechanism is unknown. PMID:28755409

Neutralization of glucagon by antiserum as a tool in glucagon physiology. Lack of depression of basal blood glucose after antiserum treatment in rats

DEFF Research Database (Denmark)

Holst, J J; Galbo, H; Richter, Erik

1978-01-01

to more than one-third of the total glucagon content in the rat pancreas. That rapid, extensive, and lasting neutralization of glucagon had taken place after antiserum treatment was indicated by the following findings: When examined more than 1 h after the injection and after 60 min of exercise......-stimulated glucagon production, all rats had excess free antibodies in plasma. The concentration of free glucagon was lowered to one-third of the concentration in control rats; at 37 degrees C plasma samples could bind 25% of additional 300 pmol/liter of glucagon in 10 s, and 69% in 120 s; the glycemic response...... was lowered beyond detection limit. The data indicate that the absolute concentration of glucagon in plasma is of minor importance for the maintenance of basal blood glucose in the rat....

Effects of glucagon-like peptide-1 on glucagon secretion in patients with non-alcoholic fatty liver disease

DEFF Research Database (Denmark)

Junker, Anders E; Gluud, Lise L; van Hall, Gerrit

2016-01-01

BACKGROUND & AIMS: We evaluated the glucagon-suppressive effect of glucagon-like peptide-1 (GLP-1) and its potential effects on endogenous glucose production and whole body lipolysis in non-diabetic patients with non-alcoholic fatty liver disease (NAFLD). METHODS: On two separate days 10 non-diabetic...... patients with liver biopsy-verified NAFLD (NAFLD activity score 2.5±1.0) and 10 matched controls underwent a 2-hour intravenous infusions of GLP-1 (0.8 pmol × kg(-1) × min(-1)) and placebo. Since GLP-1-mediated glucagon suppression has been shown to be glucose-dependent, plasma glucose was clamped...

Examination of intracellular protein turnover under the influence of glucagon exemplified by the 14C-BNPP inhibitable liver carboxylesterases of diabetic rats

International Nuclear Information System (INIS)

Wagenmann, F.P.

1982-01-01

To-date, there are but few studies on the synthesis and degradation of cell proteins under the influence of exogenically supplied-hormones. The thesis aimed at undertaking such a study using membrane-linked non-specific liver carboxyl esterases under the influence of glucagon. The method applied allows to simultaneously measure both the content and the metabolism of carboxyl esterases. Test animals were 24 male Wistar rats which were turned into diabetics using streptozotocine. Following a single i.p. application of 10mg BNPP/kg body weight, the animals received, s.c. injections of 1-1.5 mg zinc protamine glucagon/kg bodyweight daily. Esterase content per gram of microsomal protein dropped to some 50% during the 5-day observation period, whereas total protein concentration of the microsome fraction was reduced but lightly. Such a drop in the esterase concentration in the liver could not be found in a 28-amimal control group which received neither streptozotocine nor zinc protamine glucagon. Average halflife of carboxyl esterases was 43 h in these animals whereas it was 73 h in the animals treated with glucagon. A mathematical model of protein degradation allowed to prove that the supraproportional decrease of esterase content and the marked prolongation of average halflife in glucagon-treated animals was mainly due to a restriction of the de-novo synthesis of esterasis. (orig./MG) [de

Proteolysis in hyperthermophilic microorganisms

Directory of Open Access Journals (Sweden)

Donald E. Ward

2002-01-01

Full Text Available Proteases are found in every cell, where they recognize and break down unneeded or abnormal polypeptides or peptide-based nutrients within or outside the cell. Genome sequence data can be used to compare proteolytic enzyme inventories of different organisms as they relate to physiological needs for protein modification and hydrolysis. In this review, we exploit genome sequence data to compare hyperthermophilic microorganisms from the euryarchaeotal genus Pyrococcus, the crenarchaeote Sulfolobus solfataricus, and the bacterium Thermotoga maritima. An overview of the proteases in these organisms is given based on those proteases that have been characterized and on putative proteases that have been identified from genomic sequences, but have yet to be characterized. The analysis revealed both similarities and differences in the mechanisms utilized for proteolysis by each of these hyperthermophiles and indicated how these mechanisms relate to proteolysis in less thermophilic cells and organisms.

The biology of glucagon and the consequences of hyperglucagonemia

DEFF Research Database (Denmark)

Wewer Albrechtsen, Nicolai J; Kuhre, Rune E; Pedersen, Jens

2016-01-01

with a particular focus on diabetes, and finally speculate that the primary physiological importance of glucagon may not reside in glucose homeostasis but in regulation of amino acid metabolism exerted via a hitherto unrecognized hepato-pancreatic feedback loop.......The proglucagon-derived peptide hormone, glucagon, comprises 29 amino acids. Its secretion from the pancreatic α cells is regulated by several factors. Glucagon increases blood glucose levels through gluconeogenesis and glycogenolysis. Elevated plasma concentrations of glucagon, hyperglucagonemia......, may contribute to diabetes. However, hyperglucagonemia is also observed in other clinical conditions than diabetes, including nonalcoholic fatty liver disease, glucagon-producing tumors and after gastric bypass surgery. Here, we review the current literature on hyperglucagonemia in disease...

Differential regional metabolism of glucagon in anesthetized pigs

DEFF Research Database (Denmark)

Deacon, Carolyn F; Kelstrup, Mette; Trebbien, Ramona

2003-01-01

Glucagon metabolism under basal (endogenous) conditions and during intravenous glucagon infusion was studied in anesthetized pigs by use of midregion (M), COOH-terminal (C), and NH2-terminal (N)-RIAs. Arteriovenous concentration differences revealed a negative extraction of endogenous glucagon.......5 +/- 6.7%, M-, C-, N-RIA) and exogenous conditions (46.9 +/- 4.8, 46.4 +/- 6.0, 47.0 +/- 7.7%; M-, C-, N-RIA), indicating substantial elimination of the peptide. Hepatic glucagon extraction was undetectable under basal conditions and detected only by M-RIA (10.0 +/- 3.8%) during glucagon infusion......, indicating limited midregional cleavage of the molecule. The plasma half-life determined by C- and N-RIAs (2.7 +/- 0.2 and 2.3 +/- 0.2 min) were similar, but both were shorter than when determined by M-RIA (3.2 +/- 0.2 min, P Metabolic clearance rates were similar regardless of assay (14.4 +/- 1...

Nonsuppressed Glucagon After Glucose Challenge as a Potential Predictor for Glucose Tolerance.

Science.gov (United States)

Wagner, Róbert; Hakaste, Liisa H; Ahlqvist, Emma; Heni, Martin; Machann, Jürgen; Schick, Fritz; Van Obberghen, Emmanuel; Stefan, Norbert; Gallwitz, Baptist; Tuomi, Tiinamaija; Häring, Hans-Ulrich; Groop, Leif; Fritsche, Andreas

2017-05-01

Glucagon levels are classically suppressed after glucose challenge. It is still not clear as to whether a lack of suppression contributes to hyperglycemia and thus to the development of diabetes. We investigated the association of postchallenge change in glucagon during oral glucose tolerance tests (OGTTs), hypothesizing that higher postchallenge glucagon levels are observed in subjects with impaired glucose tolerance (IGT). Glucagon levels were measured during OGTT in a total of 4,194 individuals without diabetes in three large European cohorts. Longitudinal changes in glucagon suppression were investigated in 50 participants undergoing a lifestyle intervention. Only 66-79% of participants showed suppression of glucagon at 120 min (fold change glucagon 120/0 change glucagon 120/0 ≥1). Participants with nonsuppressed glucagon 120 had a lower risk of IGT in all cohorts (odds ratio 0.44-0.53, P change glucagon 120/0 was associated with an improvement in insulin sensitivity ( P = 0.003). We characterize nonsuppressed glucagon 120 during the OGTT. Lower glucagon suppression after oral glucose administration is associated with a metabolically healthier phenotype, suggesting that it is not an adverse phenomenon. © 2017 by the American Diabetes Association.

Effect of hyperthyroidism on clearance and secretion of glucagon in man.

Science.gov (United States)

Dimitriadis, G; Hatziagelaki, E; Mitrou, P; Lambadiari, V; Maratou, E; Raptis, A E; Gerich, J E; Raptis, S A

2011-04-01

Glucagon has been proposed to contribute to the increased glucose production found in hyperthyroidism. However, fasting plasma glucagon levels are not increased in hyperthyroidism suggesting that the activity of the α-cell is normal. Nevertheless, an increase in the clearance rate of glucagon may mask increased glucagon secretion. This study was designed to examine the effects of hyperthyroidism on the kinetics of glucagon. A primed-continuous infusion of glucagon was administered to 9 euthyroid and 9 hyperthyroid subjects at 3 sequential rates (1,200, 3,000 and 6,000 pg/kg/min, each given for 2 h). Arterialized blood was drawn at 15-30 min intervals for determination of glucagon. Fasting plasma glucagon levels were comparable in euthyroids (195±8 pg/ml) and hyperthyroids (231±16 pg/ml). During infusions (1,200, 3,000 and 6,000 pg/kg/min), plasma glucagon increased to 387±19, 624±44 and 977±51 pg/ml in euthyroids and to 348±23, 597±42 and 938±56 pg/ml in hyperthyroids respectively. At these infusion rates, metabolic clearance of glucagon (ml/kg/min) was 6.6±0.5, 7.4±0.6 and 7.9±0.5 in euthyroids and 12.6±2, 8.9±1 and 8.8±0.6 in hyperthyroids, respectively. Metabolic clearance of glucagon differed between hyperthyroids and euthyroids at 1 200 pg/kg/min infusion rate (p=0.001). The basal delivery rate of glucagon (ng/kg/min) was 1.3±0.1 in euthyroids and 2.9±0.6 in hyperthyroids (p=0.0005). In hyperthyroidism, the secretion and metabolic clearance rates of glucagon are increased. These effects may explain the changes in plasma glucagon levels observed in hyperthyroidism and support the important role of glucagon in increasing endogenous glucose production in this condition. © J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York.

Exenatide, a Glucagon-like Peptide-1 Receptor Agonist, Acutely Inhibits Intestinal Lipoprotein Production in Healthy Humans

NARCIS (Netherlands)

Xiao, Changting; Bandsma, Robert H. J.; Dash, Satya; Szeto, Linda; Lewis, Gary F.

Objective-Incretin-based therapies for the treatment of type 2 diabetes mellitus improve plasma lipid profiles and postprandial lipemia, but their exact mechanism of action remains unclear. Here, we examined the acute effect of the glucagon-like peptide-1 receptor agonist, exenatide, on intestinal

Insulin release by glucagon and secretin

DEFF Research Database (Denmark)

Kofod, Hans; Andreu, D; Thams, P

1988-01-01

Secretin and glucagon potentiate glucose-induced insulin release. We have compared the effects of secretin and glucagon with that of four hybrid molecules of the two hormones on insulin release and formation of cyclic AMP (cAMP) in isolated mouse pancreatic islets. All six peptides potentiated...... the release of insulin at 10 mM D-glucose, and their effects were indistinguishable with respect to the dynamics of release, dose-response relationship, and glucose dependency. However, measurements of cAMP accumulation in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (10(-4) M...... potentiating effects of secretin and glucagon on glucose-induced insulin release, their modes of action may be different....

The effect of glucagon-like peptide I (GLP-I) on glucose elimination in healthy subjects depends on the pancreatic glucoregulatory hormones

DEFF Research Database (Denmark)

Toft-Nielson, M; Madsbad, Sten; Holst, J J

1996-01-01

Glucagon-like peptide I (GLP-I) decreases plasma glucose in type II diabetic patients and in healthy subjects indirectly by stimulation of insulin and inhibition of glucagon secretion, whereby the hepatic glucose production decreases. However, recent studies indicate that GLP-I may also directly...... min, a 25-g intravenous glucose tolerance test (IVGTT) was carried out, and plasma concentrations of glucose, insulin, glucagon, and GLP-I were measured during the following 2 h. IVGTT together with GLP-I infusion significantly elevated insulin during 500 microgram/h SS but not during 1,000 microgram....../h SS. Plasma glucagon was strongly depressed in all experiments. During 500 microgram/h SS, the glucose disappearance constant, Kg, was 0.49 +/- 0.03% per minute with GLP-I and 0.39 +/- 0.04% per minute with saline (n = 8, P = 0.004). With 1,000 microgram/h SS, Kg was 0.42 +/- 0.03% per minute with GLP...

Multiple Factors Related to the Secretion of Glucagon-Like Peptide-1

Directory of Open Access Journals (Sweden)

XingChun Wang

2015-01-01

Full Text Available The glucagon-like peptide-1 is secreted by intestinal L cells in response to nutrient ingestion. It regulates the secretion and sensitivity of insulin while suppressing glucagon secretion and decreasing postprandial glucose levels. It also improves beta-cell proliferation and prevents beta-cell apoptosis induced by cytotoxic agents. Additionally, glucagon-like peptide-1 delays gastric emptying and suppresses appetite. The impaired secretion of glucagon-like peptide-1 has negative influence on diabetes, hyperlipidemia, and insulin resistance related diseases. Thus, glucagon-like peptide-1-based therapies (glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are now well accepted in the management of type 2 diabetes. The levels of glucagon-like peptide-1 are influenced by multiple factors including a variety of nutrients. The component of a meal acts as potent stimulants of glucagon-like peptide-1 secretion. The levels of its secretion change with the intake of different nutrients. Some drugs also have influence on GLP-1 secretion. Bariatric surgery may improve metabolism through the action on GLP-1 levels. In recent years, there has been a great interest in developing effective methods to regulate glucagon-like peptide-1 secretion. This review summarizes the literature on glucagon-like peptide-1 and related factors affecting its levels.

11S Storage globulin from pumpkin seeds: regularities of proteolysis by papain.

Science.gov (United States)

Rudakova, A S; Rudakov, S V; Kakhovskaya, I A; Shutov, A D

2014-08-01

Limited proteolysis of the α- and β-chains and deep cleavage of the αβ-subunits by the cooperative (one-by-one) mechanism was observed in the course of papain hydrolysis of cucurbitin, an 11S storage globulin from seeds of the pumpkin Cucurbita maxima. An independent analysis of the kinetics of the limited and cooperative proteolyses revealed that the reaction occurs in two successive steps. In the first step, limited proteolysis consisting of detachments of short terminal peptides from the α- and β-chains was observed. The cooperative proteolysis, which occurs as a pseudo-first order reaction, started at the second step. Therefore, the limited proteolysis at the first step plays a regulatory role, impacting the rate of deep degradation of cucurbitin molecules by the cooperative mechanism. Structural alterations of cucurbitin induced by limited proteolysis are suggested to generate its susceptibility to cooperative proteolysis. These alterations are tentatively discussed on the basis of the tertiary structure of the cucurbitin subunit pdb|2EVX in comparison with previously obtained data on features of degradation of soybean 11S globulin hydrolyzed by papain.

Perlecan and the Blood-Brain Barrier: Beneficial Proteolysis?

Directory of Open Access Journals (Sweden)

Jill eRoberts

2012-08-01

Full Text Available The cerebral microvasculature is important for maintaining brain homeostasis. This is achieved via the blood-brain barrier (BBB, composed of endothelial cells with specialized tight junctions, astrocytes and a basement membrane. Prominent components of the basement membrane extracellular matrix (ECM include fibronectin, laminin, collagen IV and perlecan, all of which regulate cellular processes via signal transduction through various cell membrane bound ECM receptors. Expression and proteolysis of these ECM components can be rapidly altered during pathological states of the central nervous system. In particular, proteolysis of perlecan, a heparan sulfate proteoglycan, occurs within hours following ischemia induced by experimental stroke. Proteolysis of ECM components following stroke results in the degradation of the basement membrane and further disruption of the BBB. While it is clear that such proteolysis has negative consequences for the BBB, we propose that it also may lead to generation of ECM protein fragments, including the C-terminal domain V (DV of perlecan, that potentially have a positive influence on other aspects of CNS health. Indeed, perlecan DV has been shown to be persistently generated after stroke and beneficial as a neuroprotective molecule and promoter of post-stroke brain repair. This mini-review will discuss beneficial roles of perlecan protein fragment generation within the brain during stroke.

Polyomic profiling reveals significant hepatic metabolic alterations in glucagon-receptor (GCGR knockout mice: implications on anti-glucagon therapies for diabetes

Directory of Open Access Journals (Sweden)

Molloy Mark P

2011-06-01

Full Text Available Abstract Background Glucagon is an important hormone in the regulation of glucose homeostasis, particularly in the maintenance of euglycemia and prevention of hypoglycemia. In type 2 Diabetes Mellitus (T2DM, glucagon levels are elevated in both the fasted and postprandial states, which contributes to inappropriate hyperglycemia through excessive hepatic glucose production. Efforts to discover and evaluate glucagon receptor antagonists for the treatment of T2DM have been ongoing for approximately two decades, with the challenge being to identify an agent with appropriate pharmaceutical properties and efficacy relative to potential side effects. We sought to determine the hepatic & systemic consequence of full glucagon receptor antagonism through the study of the glucagon receptor knock-out mouse (Gcgr-/- compared to wild-type littermates. Results Liver transcriptomics was performed using Affymetric expression array profiling, and liver proteomics was performed by iTRAQ global protein analysis. To complement the transcriptomic and proteomic analyses, we also conducted metabolite profiling (~200 analytes using mass spectrometry in plasma. Overall, there was excellent concordance (R = 0.88 for changes associated with receptor knock-out between the transcript and protein analysis. Pathway analysis tools were used to map the metabolic processes in liver altered by glucagon receptor ablation, the most notable being significant down-regulation of gluconeogenesis, amino acid catabolism, and fatty acid oxidation processes, with significant up-regulation of glycolysis, fatty acid synthesis, and cholesterol biosynthetic processes. These changes at the level of the liver were manifested through an altered plasma metabolite profile in the receptor knock-out mice, e.g. decreased glucose and glucose-derived metabolites, and increased amino acids, cholesterol, and bile acid levels. Conclusions In sum, the results of this study suggest that the complete ablation

Feedback suppression of meal-induced glucagon-like peptide-1 (GLP-1) secretion mediated through elevations in intact GLP-1 caused by dipeptidyl peptidase-4 inhibition

DEFF Research Database (Denmark)

Baranov, Oleg; Kahle, Melanie; Deacon, Carolyn F

2016-01-01

AIM: To compare directly the clinical effects of vildagliptin and sitagliptin in patients with type 2 diabetes, with a special emphasis on incretin hormones and L-cell feedback inhibition induced by dipeptidyl peptidase (DPP-4) inhibition. METHODS: A total of 24 patients (12 on a diet/exercise re......AIM: To compare directly the clinical effects of vildagliptin and sitagliptin in patients with type 2 diabetes, with a special emphasis on incretin hormones and L-cell feedback inhibition induced by dipeptidyl peptidase (DPP-4) inhibition. METHODS: A total of 24 patients (12 on a diet....../exercise regimen, 12 on metformin) were treated, in randomized order, for 7-9 days, with either vildagliptin (50 mg twice daily = 100 mg/d), sitagliptin (100 mg once daily in those on diet, 50 mg twice daily in those on metformin treatment = 100 mg/d) or placebo (twice daily). A mixed-meal test was performed....... RESULTS: Intact glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide concentrations were doubled by both DPP-4 inhibitors. Meal-related total GLP-1 responses were reduced by vildagliptin and sitagliptin treatment alike in the majority of patients (vildagliptin: p = 0...

EJE PRIZE 2018: A gut feeling about glucagon.

Science.gov (United States)

Knop, Filip K

2018-06-01

Hyperglucagonaemia (in the fasting as well as in the postprandial state) is considered a core pathophysiological component of diabetes and is found to contribute substantially to the hyperglycaemic state of diabetes. Hyperglucagonaemia is usually viewed upon as a consequence of pancreatic alpha cell insensitivity to the glucagon-suppressive effects of glucose and insulin. Since we observed that the well-known hyperglucagonaemic response to oral glucose in patients with type 2 diabetes is exchanged by normal suppression of plasma glucagon levels following isoglycaemic intravenous glucose administration in these patients, we have been focusing on the gut and gut-derived factors as potential mediators of diabetic hyperglucagonaemia. In a series of clinical experiments, we have elucidated the role of gut-derived factors in diabetic hyperglucagonaemia and shown that glucose-dependent insulinotropic polypeptide promotes hyperglucagonaemia and that glucagon, hitherto considered a pancreas-specific hormone, may also be secreted from extrapancreatic tissues - most likely from proglucagon-producing enteroendocrine cells. Furthermore, our observation that fasting hyperglucagonaemia is unrelated to the diabetic state, but strongly correlates with obesity, liver fat content and circulating amino acids, has made us question the common 'pancreacentric' and 'glucocentric' understanding of hyperglucagonaemia and led to the hypothesis that steatosis-induced hepatic glucagon resistance (and reduced amino acid turnover) and compensatory glucagon secretion mediated by increased circulating amino acids constitute a complete endocrine feedback system: the liver-alpha cell axis. This article summarises the physiological regulation of glucagon secretion in humans and considers new findings suggesting that the liver and the gut play key roles in determining fasting and postabsorptive circulating glucagon levels. © 2018 European Society of Endocrinology.

Low sensitivity of glucagon provocative testing for diagnosis of pheochromocytoma.

Science.gov (United States)

Lenders, Jacques W M; Pacak, Karel; Huynh, Thanh-Truc; Sharabi, Yehonatan; Mannelli, Massimo; Bratslavsky, Gennady; Goldstein, David S; Bornstein, Stefan R; Eisenhofer, Graeme

2010-01-01

Pheochromocytomas can usually be confirmed or excluded using currently available biochemical tests of catecholamine excess. Follow-up tests are, nevertheless, often required to distinguish false-positive from true-positive results. The glucagon stimulation test represents one such test; its diagnostic utility is, however, unclear. The aim of the study was to determine the diagnostic power of the glucagon test to exclude or confirm pheochromocytoma. Glucagon stimulation tests were carried out at three specialist referral centers in 64 patients with pheochromocytoma, 38 patients in whom the tumor was excluded, and in a reference group of 36 healthy volunteers. Plasma concentrations of norepinephrine and epinephrine were measured before and after glucagon administration. Several absolute and relative test criteria were used for calculating diagnostic sensitivity and specificity. Expression of the glucagon receptor was examined in pheochromocytoma tumor tissue from a subset of patients. Larger than 3-fold increases in plasma norepinephrine after glucagon strongly predicted the presence of a pheochromocytoma (100% specificity and positive predictive value). However, irrespective of the various criteria examined, glucagon-provoked increases in plasma catecholamines revealed the presence of the tumor in less than 50% of affected patients. Diagnostic sensitivity was particularly low in patients with pheochromocytomas due to von Hippel-Lindau syndrome. Tumors from these patients showed no significant expression of the glucagon receptor. The glucagon stimulation test offers insufficient diagnostic sensitivity for reliable exclusion or confirmation of pheochromocytoma. Because of this and the risk of hypertensive complications, the test should be abandoned in routine clinical practice.

[The physiology of glucagon-like peptide-1 and its role in the pathophysiology of type 2 diabetes mellitus].

Science.gov (United States)

Escalada, Francisco Javier

2014-09-01

The hormone glucagon-like peptide-1 (GLP-1) is synthesized and secreted by L cells in the small intestine in response to food ingestion. After reaching the general circulation it has a half-life of 2-3 minutes due to degradation by the enzyme dipeptidyl peptidase-4. Its physiological role is directed to control plasma glucose concentration, though GLP-1 also plays other different metabolic functions following nutrient absorption. Biological activities of GLP-1 include stimulation of insulin biosynthesis and glucose-dependent insulin secretion by pancreatic beta cell, inhibition of glucagon secretion, delay of gastric emptying and inhibition of food intake. GLP-1 is able to reduce plasma glucose levels in patients with type 2 diabetes and also can restore beta cell sensitivity to exogenous secretagogues, suggesting that the increasing GLP-1 concentration may be an useful therapeutic strategy for the treatment of patients with type 2 diabetes. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Efficacy determinants of subcutaneous microdose glucagon during closed-loop control.

Science.gov (United States)

Russell, Steven J; El-Khatib, Firas H; Nathan, David M; Damiano, Edward R

2010-11-01

During a previous clinical trial of a closed-loop blood glucose (BG) control system that administered insulin and microdose glucagon subcutaneously, glucagon was not uniformly effective in preventing hypoglycemia (BGMicrodose glucagon administration was relatively ineffective in preventing hypoglycemia when plasma insulin levels exceeded the controller's online estimate by >60%. After the algorithm PK parameters were globally adjusted, insulin dosing was more conservative and microdose glucagon administration was very effective in reducing hypoglycemia while maintaining normal plasma glucagon levels. Improvements in the accuracy of the controller's online estimate of plasma insulin levels could be achieved if ultrarapid-acting insulin formulations could be developed with faster absorption and less intra- and intersubject variability than the current insulin analogs available today. © 2010 Diabetes Technology Society.

Proteolysis in model Portuguese cheeses: Effects of rennet and starter culture.

Science.gov (United States)

Pereira, Cláudia I; Gomes, Eliza O; Gomes, Ana M P; Malcata, F Xavier

2008-06-01

To shed further light onto the mechanisms of proteolysis that prevail throughout ripening of Portuguese cheeses, model cheeses were manufactured from bovine milk, following as much as possible traditional manufacture practices - using either animal or plant rennet. The individual role upon proteolysis of two (wild) strains of lactic acid bacteria - viz. Lactococcus lactis and Lactobacillus brevis, which are normally found to high viable numbers in said cheeses, was also considered, either as single or mixed cultures. Our experimental results confirmed the influence of rennet on the proteolysis extent, but not on proteolysis depth. On the other hand, the aforementioned strains clearly improved release of medium- and small-sized peptides, and contributed as well to the free amino acid pool in cheese. Copyright © 2007 Elsevier Ltd. All rights reserved.

Factors influencing insulin and glucagon secretion in lean and genetically obese mice

International Nuclear Information System (INIS)

Beloff-Chain, A.; Newman, M.E.; Mansford, K.R.L.

1977-01-01

The control of 125 I-labelled insulin and glucagon secretion from isolated pancreatic islets of lean and genetically obese mice has been compared. The enlarged islets of obese mouse pancreas and islets of obese mice maintained on a restricted diet manifested a greater response to glucose stimulation of insulin secretion than the lean mice islets. The glucagon content of the islets, the secretion of glucagon in a medium containing 150 mg% glucose and the stimulation of glucagon secretion by arginine did not differ significantly in the two groups. Adrenaline stimulated glucagon secretion in vitro from obese mice but not from lean mice. Antiinsulin serum injections into obese mice increased the plasma glucagon levels about twofold and had no effect on glucagon levels in lean mice, although the level of hyperglycaemia was the same in both groups. It is suggested that the suppression of glucagon release by glucose requires a higher concentration of insulin in the obese mouse pancreas than in lean mice. (orig./AJ) [de

Factors influencing insulin and glucagon secretion in lean and genetically obese mice

Energy Technology Data Exchange (ETDEWEB)

Beloff-Chain, A; Newman, M E; Mansford, K R.L. [Imperial Coll. of Science and Technology, London (UK). Dept. of Biochemistry

1977-01-01

The control of /sup 125/I-labelled insulin and glucagon secretion from isolated pancreatic islets of lean and genetically obese mice has been compared. The enlarged islets of obese mouse pancreas and islets of obese mice maintained on a restricted diet manifested a greater response to glucose stimulation of insulin secretion than the lean mice islets. The glucagon content of the islets, the secretion of glucagon in a medium containing 150 mg% glucose and the stimulation of glucagon secretion by arginine did not differ significantly in the two groups. Adrenaline stimulated glucagon secretion in vitro from obese mice but not from lean mice. Antiinsulin serum injections into obese mice increased the plasma glucagon levels about twofold and had no effect on glucagon levels in lean mice, although the level of hyperglycaemia was the same in both groups. It is suggested that the suppression of glucagon release by glucose requires a higher concentration of insulin in the obese mouse pancreas than in lean mice.

Oxytocin increases extrapancreatic glucagon secretion and glucose production in pancreatectomized dogs

International Nuclear Information System (INIS)

Altszuler, N.; Puma, F.; Winkler, B.; Fontan, N.; Saudek, C.D.

1986-01-01

Infusion of oxytocin into normal dogs increases plasma levels of insulin and glucagon and glucose production and uptake. To determine whether infused oxytocin also increases glucagon secretion from extrapancreatic sites, pancreatectomized dogs, off insulin of 18 hr, were infused with oxytocin and plasma glucagon, and glucose production and uptake were measured using the [6- 3 H]glucose primer-infusion technique. The diabetic dogs, in the control period, had elevated plasma glucose and glucagon levels, an increased rate of glucose production, and a relative decrease in glucose uptake (decreased clearance). Infusion of oxytocin (500 μU/kg/min) caused a rise in plasma glucagon and glucose levels, increased glucose production, and further decreased glucose clearance. it is concluded that oxytocin can stimulate secretion of extrapancreatic glucagon, which contributes to the increased glucose production

Effect of Oxyntomodulin, Glucagon, GLP-1 and Combined Glucagon +GLP-1 Infusion on Food Intake, Appetite and Resting Energy Expenditure

DEFF Research Database (Denmark)

Bagger, Jonatan I; Holst, Jens J; Hartmann, Bolette

2015-01-01

Context: The gut hormone, oxyntomodulin, is a proglucagon product with body weight-lowering potential. It binds to both the glucagon-like peptide-1 (GLP-1) receptor and the glucagon receptor; however, the mechanism behind the body weight-lowering effect remains elusive. Objective: We wanted.......86 pmol × kg−1 × min−1), oxyntomodulin (3 pmol × kg−1 × min−1), or glucagon+GLP-1 (same doses). Main Outcome Measures: We evaluated resting energy expenditure (measured as oxygen uptake, gastric emptying (GE), composite appetite scores (CAS), and food intake. Results: Oxyntomodulin, GLP-1, and GLP-1...

Intra-islet glucagon secretion and action in the regulation of glucose homeostasis.

Directory of Open Access Journals (Sweden)

Qinghua eWang

2013-01-01

Full Text Available Glucagon, a key hormone in the regulation of glucose homeostasis, acts as a counter-regulatory hormone to insulin by promoting hepatic glucose output. Under normal conditions, insulin and glucagon operate in concert to maintain the glucose level within a narrow physiological range. In diabetes, however, while insulin secretion or action is insufficient, the production and secretion of glucagon are excessive, contributing to the development of diabetic hyperglycemia. Within an islet, intra-islet insulin, in cooperation with intra-islet GABA, suppresses glucagon secretion via direct modulation of -cell intracellular signaling pathways involving Akt activation, GABA receptor phosphorylation and the receptor plasma membrane translocation, while intra-islet glucagon plays an important role in modulating β-cell function and insulin secretion. Defects in the insulin-glucagon fine-tuning machinery may result in β-cell glucose incompetence, leading to unsuppressed glucagon secretion and subsequent hyperglycemia, which often occur under extreme conditions of glucose influx or efflux. Therefore, deciphering the precise molecular mechanisms underlying glucagon secretion and action will facilitate our understanding of glucagon physiology, in particular, its role in regulating islet β-cell function, and hence the mechanisms behind body glucose homeostasis.

Complementary methods for the identification of substrates of proteolysis.

Science.gov (United States)

Pham, Victoria C; Anania, Veronica G; Phung, Qui T; Lill, Jennie R

2014-01-01

Proteolysis describes the cleavage of proteins into smaller components, which in vivo occurs typically to either activate or impair the functionality of cellular proteins. Proteolysis can occur during cellular homeostasis or can be induced due to external stress stimuli such as heat, biological or chemical insult, and is mediated by the activity of cellular enzymes, namely, proteases. Proteolytic cleavage of proteins can influence protein activation by exposing an active site or disrupting inhibitor binding. Conversely, proteolytic cleavage of many proteins has also been shown to lead to protein degradation resulting in inactivation of the substrate. Thousands of proteolytic events are known to take place in regulated cellular processes such as apoptosis and pyroptosis, however, their individual contribution to these processes remains poorly understood. Additionally, many cellular homeostatic processes are regulated by proteolytic events, however, in some cases, few proteolytic substrates have been identified. To gain further insight into the mechanism of action of these cellular processes, and to characterize biomarkers of cell death and other pathological indications, it is imperative to utilize a complete arsenal of tools for studying proteolysis events in vivo and in vitro. In this chapter, we focus on alternative methodologies to N-terminomics for profiling substrates of proteolysis and describe an additional suite of tools including orthogonal biophysical separation techniques such as COFRADIC or GASSP, and affinity capture tools that can enrich for newly formed C-termini (C-terminomics) generated as a result of caspase-mediated proteolysis. © 2014 Elsevier Inc. All rights reserved.

Pre-cure freezing affects proteolysis in dry-cured hams.

Science.gov (United States)

Bañón, S; Cayuela, J M; Granados, M V; Garrido, M D

1999-01-01

Several parameters (sodium chloride, moisture, intramuscular fat, total nitrogen, non-protein nitrogen, white precipitates, free tyrosine, L* a* b* values and acceptability) related with proteolysis during the curing were compared in dry-cured hams manufactured from refrigerated and frozen/thawed raw material. Pre-cure freezing increased the proteolysis levels significantly (pcured meat, although it does not significantly affect the sensory quality of the dry-cured ham.

A K ATP channel-dependent pathway within alpha cells regulates glucagon release from both rodent and human islets of Langerhans.

Science.gov (United States)

MacDonald, Patrick E; De Marinis, Yang Zhang; Ramracheya, Reshma; Salehi, Albert; Ma, Xiaosong; Johnson, Paul R V; Cox, Roger; Eliasson, Lena; Rorsman, Patrik

2007-06-01

Glucagon, secreted from pancreatic islet alpha cells, stimulates gluconeogenesis and liver glycogen breakdown. The mechanism regulating glucagon release is debated, and variously attributed to neuronal control, paracrine control by neighbouring beta cells, or to an intrinsic glucose sensing by the alpha cells themselves. We examined hormone secretion and Ca(2+) responses of alpha and beta cells within intact rodent and human islets. Glucose-dependent suppression of glucagon release persisted when paracrine GABA or Zn(2+) signalling was blocked, but was reversed by low concentrations (1-20 muM) of the ATP-sensitive K(+) (KATP) channel opener diazoxide, which had no effect on insulin release or beta cell responses. This effect was prevented by the KATP channel blocker tolbutamide (100 muM). Higher diazoxide concentrations (>/=30 muM) decreased glucagon and insulin secretion, and alpha- and beta-cell Ca(2+) responses, in parallel. In the absence of glucose, tolbutamide at low concentrations (10 muM) were inhibitory. In the presence of a maximally inhibitory concentration of tolbutamide (0.5 mM), glucose had no additional suppressive effect. Downstream of the KATP channel, inhibition of voltage-gated Na(+) (TTX) and N-type Ca(2+) channels (omega-conotoxin), but not L-type Ca(2+) channels (nifedipine), prevented glucagon secretion. Both the N-type Ca(2+) channels and alpha-cell exocytosis were inactivated at depolarised membrane potentials. Rodent and human glucagon secretion is regulated by an alpha-cell KATP channel-dependent mechanism. We propose that elevated glucose reduces electrical activity and exocytosis via depolarisation-induced inactivation of ion channels involved in action potential firing and secretion.

Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist

Science.gov (United States)

Johnson, David G.; Ulichny Goebel, Camy; Hruby, Victor J.; Bregman, Marvin D.; Trivedi, Dev

1982-02-01

The glucagon analog [l-Nα-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.

Laser-light backscattering response to water content and proteolysis in dry-cured ham

DEFF Research Database (Denmark)

Fulladosa, E.; Rubio-Celorio, M.; Skytte, Jacob Lercke

2017-01-01

on the acquisition conditions used. Laser backscattering was influenced by both dryness and proteolysis intensity showing an average light intensity decrease of 0.2 when decreasing water content (1% weight loss) and increasing proteolysis (equivalent to one-hour enzyme action). However, a decrease of scattering area...... was only detected when the water content was decreased (618 mm(2) per 1% weight loss). Changes on scattering of light profiles were only observed when the water content changed. Although there is a good correlation between water content and LBI parameters when analysing commercial samples, proteolysis...... of laser incidence) and to analyse the laser-light backscattering changes caused by additional hot air drying and proteolysis of dry-cured ham slices. The feasibility of the technology to determine water content and proteolysis (which is related to textural characteristics) of commercial sliced dry...

Evaluation of beta-cell secretory capacity using glucagon-like peptide 1

DEFF Research Database (Denmark)

Vilsbøll, Tina; Nielsen, Mette Toft; Krarup, T

2000-01-01

Beta-cell secretory capacity is often evaluated with a glucagon test or a meal test. However, glucagon-like peptide 1 (GLP-1) is the most insulinotropic hormone known, and the effect is preserved in type 2 diabetic patients.......Beta-cell secretory capacity is often evaluated with a glucagon test or a meal test. However, glucagon-like peptide 1 (GLP-1) is the most insulinotropic hormone known, and the effect is preserved in type 2 diabetic patients....

Glucagon-like peptide-1 inhibits blood-brain glucose transfer in humans

DEFF Research Database (Denmark)

Lerche, Susanne; Brock, Birgitte; Rungby, Jørgen

2008-01-01

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) has many effects on glucose homeostasis, and GLP-1 receptors are broadly represented in many tissues including the brain. Recent research in rodents suggests a protective effect of GLP-1 on brain tissue. The mechanism is unknown. We therefore tested......-independent effect of GLP-1 on unidirectional glucose transport into the brain during a pituitary-pancreatic normoglycemic (plasma glucose approximately 4.5 mmol/l) clamp with 18-fluoro-deoxy-glucose as tracer. RESULTS: On average, GLP-1 reduced cerebral glucose transport by 27% in total cerebral gray matter (P = 0...... that a hormone involved in postprandial glucose regulation also limits glucose delivery to brain tissue and hence provides a possible regulatory mechanism for the link between plasma glucose and brain glucose. Because GLP-1 reduces glucose uptake across the intact blood-brain barrier at normal glycemia, GLP-1...

The role of glucagon-like peptide-1 impairment in obesity and potential therapeutic implications

DEFF Research Database (Denmark)

Madsbad, S

2014-01-01

glucagon secretion from the pancreas in response to food ingestion. Evidence suggests that the action or effect of GLP-1 may be impaired in obese subjects, even in those with normal glucose tolerance. GLP-1 impairment may help explain the increased gastric emptying and decreased satiety signalling seen...... in obesity. Incretin impairment, probably associated with reduced insulinotropic potency of GLP-1, is also characteristic of type 2 diabetes (T2D). Therefore, it is possible that incretin impairment may contribute to the pathophysiological bridge between obesity and T2D. This review summarises current......The hormone glucagon-like peptide-1 (GLP-1) is released from the gut in response to food intake. It acts as a satiety signal, leading to reduced food intake, and also as a regulator of gastric emptying. Furthermore, GLP-1 functions as an incretin hormone, stimulating insulin release and inhibiting...

Phenylbutyric acid rescues endoplasmic reticulum stress-induced suppression of APP proteolysis and prevents apoptosis in neuronal cells.

Directory of Open Access Journals (Sweden)

Jesse C Wiley

Full Text Available BACKGROUND: The familial and sporadic forms of Alzheimer's disease (AD have an identical pathology with a severe disparity in the time of onset [1]. The pathological similarity suggests that epigenetic processes may phenocopy the Familial Alzheimer's disease (FAD mutations within sporadic AD. Numerous groups have demonstrated that FAD mutations in presenilin result in 'loss of function' of gamma-secretase mediated APP cleavage [2], [3], [4], [5]. Accordingly, ER stress is prominent within the pathologically impacted brain regions in AD patients [6] and is reported to inhibit APP trafficking through the secretory pathway [7], [8]. As the maturation of APP and the cleaving secretases requires trafficking through the secretory pathway [9], [10], [11], we hypothesized that ER stress may block trafficking requisite for normal levels of APP cleavage and that the small molecular chaperone 4-phenylbutyrate (PBA may rescue the proteolytic deficit. METHODOLOGY/PRINCIPAL FINDINGS: The APP-Gal4VP16/Gal4-reporter screen was stably incorporated into neuroblastoma cells in order to assay gamma-secretase mediated APP proteolysis under normal and pharmacologically induced ER stress conditions. Three unrelated pharmacological agents (tunicamycin, thapsigargin and brefeldin A all repressed APP proteolysis in parallel with activation of unfolded protein response (UPR signaling-a biochemical marker of ER stress. Co-treatment of the gamma-secretase reporter cells with PBA blocked the repressive effects of tunicamycin and thapsigargin upon APP proteolysis, UPR activation, and apoptosis. In unstressed cells, PBA stimulated gamma-secretase mediated cleavage of APP by 8-10 fold, in the absence of any significant effects upon amyloid production, by promoting APP trafficking through the secretory pathway and the stimulation of the non-pathogenic alpha/gamma-cleavage. CONCLUSIONS/SIGNIFICANCE: ER stress represses gamma-secretase mediated APP proteolysis, which replicates

The effect of genetically engineered glucagon on glucose recovery after hypoglycaemia in man

DEFF Research Database (Denmark)

Hvidberg, A; Jørgensen, S; Hilsted, J

1992-01-01

To compare the effect on glucose recovery after insulin-induced hypoglycaemia of intramuscular genetically engineered glucagon, intramuscular glucagon from pancreatic extraction and intravenous glucose, we examined 10 healthy subjects during blockage of glucose counterregulation with somatostatin...... appearance rate were far more protracted after i.m. glucagon than after i.v. glucose. These results suggest that genetically engineered glucagon and glucagon from pancreatic extraction have a similar effect on hepatic glucose production rate. Due to the protracted effect of intramuscular glucagon, a combined......, propranolol and phentolamine. Each subject was studied on three separate occasions. Thirty min after a bolus injection of 0.075 iu soluble insulin per kilogram body weight the subjects received one of the following treatments: 1 mg glucagon from pancreatic extraction intramuscularly; 1 mg genetically...

Glucagon antagonism as a potential therapeutic target in type 2 diabetes

DEFF Research Database (Denmark)

Bagger, J I; Knop, F K; Holst, Jens Juul

2011-01-01

Glucagon is a hormone secreted from the alpha cells of the pancreatic islets. Through its effect on hepatic glucose production (HGP), glucagon plays a central role in the regulation of glucose homeostasis. In patients with type 2 diabetes mellitus (T2DM), abnormal regulation of glucagon secretion...

Exploring the role of glucagon in glucose homeostasis

NARCIS (Netherlands)

Dongen, Maria Gertrud Jobina van

2015-01-01

The aim of this thesis was to gain further insight into the role of glucagon in glucose homeostasis in healthy volunteers and type 2 diabetes mellitus (T2DM) patients, and to explore the novel antisense glucagon receptor antagonist. Chapter 2 showed that the effect of meal replacers containing

Rescue of a pathogenic mutant human glucagon receptor by pharmacological chaperones.

Science.gov (United States)

Yu, Run; Chen, Chun-Rong; Liu, Xiaohong; Kodra, János T

2012-10-01

We have previously demonstrated that a homozygous inactivating P86S mutation of the glucagon receptor (GCGR) causes a novel human disease of hyperglucagonemia, pancreatic α-cell hyperplasia, and pancreatic neuroendocrine tumors (Mahvash disease). The mechanisms for the decreased activity of the P86S mutant (P86S) are abnormal receptor localization to the endoplasmic reticulum (ER) and defective interaction with glucagon. To search for targeted therapies for Mahvash disease, we examined whether P86S can be trafficked to the plasma membrane by pharmacological chaperones and whether novel glucagon analogs restore effective receptor interaction. We used enhanced green fluorescent protein-tagged P86S stably expressed in HEK 293 cells to allow fluorescence imaging and western blotting and molecular modeling to design novel glucagon analogs in which alanine 19 was replaced with serine or asparagine. Incubation at 27 °C largely restored normal plasma membrane localization and normal processing of P86S but osmotic chaperones had no effects. The ER stressors thapsigargin and curcumin partially rescued P86S. The lipophilic GCGR antagonist L-168,049 also partially rescued P86S, so did Cpd 13 and 15 to a smaller degree. The rescued P86S led to more glucagon-stimulated cAMP production and was internalized by glucagon. Compared with the native glucagon, the novel glucagon analogs failed to stimulate more cAMP production by P86S. We conclude that the mutant GCGR is partially rescued by several pharmacological chaperones and our data provide proof-of-principle evidence that Mahvash disease can be potentially treated with pharmacological chaperones. The novel glucagon analogs, however, failed to interact with P86S more effectively.

Model of the Glucose-Insulin-Glucagon Dynamics after Subcutaneous Administration of a Glucagon Rescue Bolus in Healthy Humans

OpenAIRE

Wendt, Sabrina Lyngbye; Møller, Jan Kloppenborg; Haidar, Ahmad; Bysted, Britta V.; Knudsen, Carsten B.; Madsen, Henrik; Jørgensen, John Bagterp

2016-01-01

In healthy individuals, insulin and glucagon work in a complex fashion to maintain blood glucose levels within a narrow range. This regulation is distorted in patients with diabetes. The hepatic glucose response due to an elevated glucagon level depends on the current insulin concentration and thus endogenous glucose production (EGP) can not be modelled without knowledge of the concentration of both hormones in plasma. Furthermore, literature suggests an upper limit to EGP irrespective of glu...

Dipeptidyl peptidase IV inhibition enhances the intestinotrophic effect of glucagon-like peptide-2 in rats and mice

DEFF Research Database (Denmark)

Hartmann, B; Thulesen, J; Kissow, Hannelouise

2000-01-01

Glucagon-like peptide-2 (GLP-2) induces intestinal growth in mice; but in normal rats, it seems less potent, possibly because of degradation of GLP-2 by the enzyme dipeptidyl peptidase IV (DPP-IV). The purpose of this study was to investigate the survival and effect of GLP-2 in rats and mice afte...

In vivo effect of an antilipolytic drug (3,5'-dimethylpyrazole) on autophagic proteolysis and autophagy-related gene expression in rat liver

International Nuclear Information System (INIS)

Donati, Alessio; Ventruti, Annamaria; Cavallini, Gabriella; Masini, Matilde; Vittorini, Simona; Chantret, Isabelle; Codogno, Patrice; Bergamini, Ettore

2008-01-01

Autophagy is an intracellular pathway induced by starvation, inhibited by nutrients, that is responsible for degradation of long-lived proteins and altered cell organelles. This process is involved in cell maintenance could be induced by antilipolytic drugs and may have anti-aging effects [A. Donati, The involvement of macroautophagy in aging and anti-aging interventions, Mol. Aspects Med. 27 (2006) 455-470]. We analyzed the effect of an intraperitoneal injection of an antilipolytic agent (3,5'-dimethylpyrazole, DMP, 12 mg/kg b.w.), that mimics nutrient shortage on autophagy and expression of autophagic genes in the liver of male 3-month-old Sprague-Dawley albino rats. Autophagy was evaluated by observing electron micrographs of the liver autophagosomal compartment and by monitoring protein degradation assessed by the release of valine into the bloodstream. LC3 gene expression, whose product is one of the best known markers of autophagy, was also monitored. As expected, DMP decreased the plasma levels of free fatty acids, glucose, and insulin and increased autophagic vacuoles and proteolysis. DMP treatment caused an increase in the expression of the LC3 gene although this occurred later than the induction of authophagic proteolysis caused by DMP. Glucose treatment rescued the effects caused by DMP on glucose and insulin plasma levels and negatively affected the rate of autophagic proteolysis, but did not suppress the positive regulatory effect on LC3 mRNA levels. In conclusion, antilipolytic drugs may induce both autophagic proteolysis and higher expression of an autophagy-related gene and the effect on autophagy gene expression might not be secondary to the stimulation of autophagic proteolysis

Characterisation of cysteine proteinases responsible for digestive proteolysis in guts of larval Western corn rootworm (Diabrotica virgifera) by expression in the yeast Pichia pastoris

NARCIS (Netherlands)

Bown, D.P.; Wilkinson, H.S.; Jongsma, M.A.; Gatehouse, J.A.

2004-01-01

Cysteine proteinases are the major class of enzymes responsible for digestive proteolysis in western corn rootworm (Diabrotica virgifera), a serious pest of maize. A larval gut extract hydrolysed typical cathepsin substrates, such as Z-phe-arg-AMC and Z-arg-arg-AMC, and hydrolysis was inhibited by

A K ATP channel-dependent pathway within alpha cells regulates glucagon release from both rodent and human islets of Langerhans.

Directory of Open Access Journals (Sweden)

Patrick E MacDonald

2007-06-01

Full Text Available Glucagon, secreted from pancreatic islet alpha cells, stimulates gluconeogenesis and liver glycogen breakdown. The mechanism regulating glucagon release is debated, and variously attributed to neuronal control, paracrine control by neighbouring beta cells, or to an intrinsic glucose sensing by the alpha cells themselves. We examined hormone secretion and Ca(2+ responses of alpha and beta cells within intact rodent and human islets. Glucose-dependent suppression of glucagon release persisted when paracrine GABA or Zn(2+ signalling was blocked, but was reversed by low concentrations (1-20 muM of the ATP-sensitive K(+ (KATP channel opener diazoxide, which had no effect on insulin release or beta cell responses. This effect was prevented by the KATP channel blocker tolbutamide (100 muM. Higher diazoxide concentrations (>/=30 muM decreased glucagon and insulin secretion, and alpha- and beta-cell Ca(2+ responses, in parallel. In the absence of glucose, tolbutamide at low concentrations (10 muM were inhibitory. In the presence of a maximally inhibitory concentration of tolbutamide (0.5 mM, glucose had no additional suppressive effect. Downstream of the KATP channel, inhibition of voltage-gated Na(+ (TTX and N-type Ca(2+ channels (omega-conotoxin, but not L-type Ca(2+ channels (nifedipine, prevented glucagon secretion. Both the N-type Ca(2+ channels and alpha-cell exocytosis were inactivated at depolarised membrane potentials. Rodent and human glucagon secretion is regulated by an alpha-cell KATP channel-dependent mechanism. We propose that elevated glucose reduces electrical activity and exocytosis via depolarisation-induced inactivation of ion channels involved in action potential firing and secretion.

Bone resorption is decreased postprandially by intestinal factors and glucagon-like peptide-2 is a possible candidate

DEFF Research Database (Denmark)

Holst, Jens Juul; Hartmann, Bolette; Gottschalck, Ida B

2007-01-01

-bowel syndrome (SBS) or total gastrectomy in order to elucidate whether the signal for the meal-induced reduction of bone resorption is initiated from the stomach or the intestine. MATERIAL AND METHODS: Bone resorption was assessed from the serum concentration of collagen type I C-telopeptide cross-links (s......OBJECTIVE: Food intake inhibits bone resorption by a mechanism thought to involve gut hormones, and the intestinotrophic glucagon-like peptide 2 (GLP-2) is a candidate because exogenous GLP-2 inhibits bone resorption in humans. The purpose of the study was to investigate patients with short...

Proteolysis and consistency of Meshanger cheese

NARCIS (Netherlands)

Jong, de L.

1978-01-01

Proteolysis in Meshanger cheese, estimated by quantitative polyacrylamide gel electrophoresis is discussed. The conversion of α _s1 -casein was proportional to rennet concentration in the cheese. Changes in consistency, after a maximum, were correlated to breakdown of

The physiology of glucagon-like peptide 1

DEFF Research Database (Denmark)

Holst, Jens Juul

2007-01-01

Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in these cells. The current knowledge regarding regulation of proglucagon gene expression in the gut...... and in the brain and mechanisms responsible for the posttranslational processing are reviewed. GLP-1 is released in response to meal intake, and the stimuli and molecular mechanisms involved are discussed. GLP-1 is extremely rapidly metabolized and inactivated by the enzyme dipeptidyl peptidase IV even before...... postprandial glucose excursions. It also inhibits gastrointestinal motility and secretion and thus acts as an enterogastrone and part of the "ileal brake" mechanism. GLP-1 also appears to be a physiological regulator of appetite and food intake. Because of these actions, GLP-1 or GLP-1 receptor agonists...

A novel nasal powder formulation of glucagon: toxicology studies in animal models

OpenAIRE

Reno, Frederick E.; Normand, Patrick; McInally, Kevin; Silo, Sherwin; Stotland, Patricia; Triest, Myriam; Carballo, Dolores; Pich?, Claude

2015-01-01

Background Glucagon nasal powder (GNP), a novel intranasal formulation of glucagon being developed to treat insulin-induced severe hypoglycemia, contains synthetic glucagon (10?% w/w), beta-cyclodextrin, and dodecylphosphocholine. The safety of this formulation was evaluated in four studies in animal models. Methods The first study evaluated 28-day sub-chronic toxicology in rats treated intranasally with 1 and 2?mg of GNP/day (0.1 and 0.2?mg glucagon/rat/day). The second study evaluated 28-da...

GLP-1 Restores Altered Insulin and Glucagon Secretion in Posttransplantation Diabetes

DEFF Research Database (Denmark)

Halden, Thea A S; Egeland, Erlend J; Åsberg, Anders

2016-01-01

OBJECTIVE: Development of posttransplantation diabetes (PTDM) is characterized by reduced insulin secretion and sensitivity. We aimed to investigate whether hyperglucagonemia could play a role in PTDM and to examine the insulinotropic and glucagonostatic effects of the incretin hormone glucagon...... h of infusion, a 2-h hyperglycemic clamp (fasting plasma glucose + 5 mmol/L) was established. Five grams of arginine was given as an intravenous bolus 10 min before termination of the clamp. RESULTS: Fasting concentrations of glucagon (P = 0.92) and insulin (P = 0.23) were similar between the groups...... to arginine (P = 0.01) but similar glucagon and proinsulin responses compared with control subjects. In the preclamp phase, GLP-1 lowered fasting plasma glucose to the same extent in both groups but reduced glucagon only in PTDM patients. During hyperglycemic clamp, GLP-1 reduced glucagon concentrations...

Intolerance reaction after application of glucagon during double contrast studies

International Nuclear Information System (INIS)

Kainberger, F.; Fruehwald, F.; Schwaighofer, B.; Lindemayr, H.

1986-01-01

Whereas intolerance reactions against contrast media are a well-known hazard during radiologic procedures, intolerance reactions to other preparations used in radiology are rare. Glucagon, frequently used to induce gastrointestinal hypotonia, is said to have almost no side-effects. A case of anaphylactic reaction during double-contrast upper gastrointestinal examination is reported. Pseudoallergic reaction to propylparaben, a preservative agent in glucagon, is suspected. IgE-antibodies to glucagon could not be detected by RAST. (orig.) [de

Pancreatic α-cell hyperplasia and hyperglucagonemia due to a glucagon receptor splice mutation

Directory of Open Access Journals (Sweden)

Etienne Larger

2016-11-01

Full Text Available Glucagon stimulates hepatic glucose production by activating specific glucagon receptors in the liver, which in turn increase hepatic glycogenolysis as well as gluconeogenesis and ureagenesis from amino acids. Conversely, glucagon secretion is regulated by concentrations of glucose and amino acids. Disruption of glucagon signaling in rodents results in grossly elevated circulating glucagon levels but no hypoglycemia. Here, we describe a patient carrying a homozygous G to A substitution in the invariant AG dinucleotide found in a 3′ mRNA splice junction of the glucagon receptor gene. Loss of the splice site acceptor consensus sequence results in the deletion of 70 nucleotides encoded by exon 9, which introduces a frame shift and an early termination signal in the receptor mRNA sequence. The mutated receptor neither bound 125I-labeled glucagon nor induced cAMP production upon stimulation with up to 1 μM glucagon. Despite the mutation, the only obvious pathophysiological trait was hyperglucagonemia, hyperaminoacidemia and massive hyperplasia of the pancreatic α-cells assessed by histology. Our case supports the notion of a hepato–pancreatic feedback system, which upon disruption leads to hyperglucagonemia and α-cell hyperplasia, as well as elevated plasma amino acid levels. Together with the glucagon-induced hypoaminoacidemia in glucagonoma patients, our case supports recent suggestions that amino acids may provide the feedback link between the liver and the pancreatic α-cells.

Impaired glucose-induced glucagon suppression after partial pancreatectomy

DEFF Research Database (Denmark)

Schrader, Henning; Menge, Bjoern A; Breuer, Thomas G K

2009-01-01

INTRODUCTION: The glucose-induced decline in glucagon levels is often lost in patients with type 2 diabetes. It is unclear whether this is due to an independent defect in alpha-cell function or secondary to the impairment in insulin secretion. We examined whether a partial pancreatectomy in humans...... would also impair postchallenge glucagon concentrations and, if so, whether this could be attributed to the reduction in insulin levels. PATIENTS AND METHODS: Thirty-six patients with pancreatic tumours or chronic pancreatitis were studied before and after approximately 50% pancreatectomy with a 240-min...... oral glucose challenge, and the plasma concentrations of glucose, insulin, C-peptide, and glucagon were determined. RESULTS: Fasting and postchallenge insulin and C-peptide levels were significantly lower after partial pancreatectomy (P

Association of fasting glucagon and proinsulin concentrations with insulin resistance

DEFF Research Database (Denmark)

Ferrannini, E; Muscelli, E; Natali, A

2007-01-01

AIMS/HYPOTHESIS: Hyperproinsulinaemia and relative hyperglucagonaemia are features of type 2 diabetes. We hypothesised that raised fasting glucagon and proinsulin concentrations may be associated with insulin resistance (IR) in non-diabetic individuals. METHODS: We measured IR [by a euglycaemic......, controlling for known determinants of insulin sensitivity (i.e. sex, age, BMI and glucose tolerance) as well as factors potentially affecting glucagon and proinsulin (i.e. fasting plasma glucose and C-peptide concentrations), glucagon and proinsulin were still positively associated, and adiponectin...

Glucagon Effects on 3H-Histamine Uptake by the Isolated Guinea-Pig Heart during Anaphylaxis

Directory of Open Access Journals (Sweden)

Mirko Rosic

2014-01-01

Full Text Available We estimated the influence of acute glucagon applications on 3H-histamine uptake by the isolated guinea-pig heart, during a single 3H-histamine passage through the coronary circulation, before and during anaphylaxis, and the influence of glucagon on level of histamine, NO, O2-, and H2O2 in the venous effluent during anaphylaxis. Before anaphylaxis, glucagon pretreatment does not change 3H-histamine Umax and the level of endogenous histamine. At the same time, in the presence of glucagon, 3H-histamine Unet is increased and backflux is decreased when compared to the corresponding values in the absence of glucagon. During anaphylaxis, in the presence of glucagon, the values of 3H-histamine Umax and Unet are significantly higher and backflux is significantly lower in the presence of glucagon when compared to the corresponding values in the absence of glucagon. The level of endogenous histamine during anaphylaxis in the presence of glucagon (6.9–7.38 × 10−8 μM is significantly lower than the histamine level in the absence of glucagon (10.35–10.45 × 10−8 μM. Glucagon pretreatment leads to a significant increase in NO release (5.69 nmol/mL in comparison with the period before glucagon administration (2.49 nmol/mL. Then, in the presence of glucagon, O2- level fails to increase during anaphylaxis. Also, our results show no significant differences in H2O2 levels before, during, and after anaphylaxis in the presence of glucagon, but these values are significantly lower than the corresponding values in the absence of glucagon. In conclusion, our results show that glucagon increases NO release and prevents the increased release of free radicals during anaphylaxis, and decreases histamine level in the venous effluent during cardiac anaphylaxis, which may be a consequence of decreased histamine release and/or intensified histamine capturing by the heart during anaphylaxis.

Glucagon effects on 3H-histamine uptake by the isolated guinea-pig heart during anaphylaxis.

Science.gov (United States)

Rosic, Mirko; Parodi, Oberdan; Jakovljevic, Vladimir; Colic, Maja; Zivkovic, Vladimir; Jokovic, Vuk; Pantovic, Suzana

2014-01-01

We estimated the influence of acute glucagon applications on (3)H-histamine uptake by the isolated guinea-pig heart, during a single (3)H-histamine passage through the coronary circulation, before and during anaphylaxis, and the influence of glucagon on level of histamine, NO, O2 (-), and H2O2 in the venous effluent during anaphylaxis. Before anaphylaxis, glucagon pretreatment does not change (3)H-histamine Umax and the level of endogenous histamine. At the same time, in the presence of glucagon, (3)H-histamine Unet is increased and backflux is decreased when compared to the corresponding values in the absence of glucagon. During anaphylaxis, in the presence of glucagon, the values of (3)H-histamine Umax and Unet are significantly higher and backflux is significantly lower in the presence of glucagon when compared to the corresponding values in the absence of glucagon. The level of endogenous histamine during anaphylaxis in the presence of glucagon (6.9-7.38 × 10(-8) μM) is significantly lower than the histamine level in the absence of glucagon (10.35-10.45 × 10(-8) μM). Glucagon pretreatment leads to a significant increase in NO release (5.69 nmol/mL) in comparison with the period before glucagon administration (2.49 nmol/mL). Then, in the presence of glucagon, O2 (-) level fails to increase during anaphylaxis. Also, our results show no significant differences in H2O2 levels before, during, and after anaphylaxis in the presence of glucagon, but these values are significantly lower than the corresponding values in the absence of glucagon. In conclusion, our results show that glucagon increases NO release and prevents the increased release of free radicals during anaphylaxis, and decreases histamine level in the venous effluent during cardiac anaphylaxis, which may be a consequence of decreased histamine release and/or intensified histamine capturing by the heart during anaphylaxis.

Design, synthesis and crystallization of a novel glucagon analog as a therapeutic agent

Energy Technology Data Exchange (ETDEWEB)

Li, Pengyun; Rogers, Tanya; Smiley, David; DiMarchi, Richard D.; Zhang, Faming, E-mail: fzhang@indiana.edu [Department of Chemistry and Biochemistry Program, Indiana University, Bloomington, Indiana 47405 (United States)

2007-07-01

The synthesis and crystallization of glucagon-Cex are reported. Glucagon and glucagon-like peptide 1 (GLP-1) are drugs or drug candidates for the treatment of metabolic diseases such as diabetes and obesity. The native hormones have pharmacological deficiencies such as short half-life and poor solubility. A novel glucagon receptor agonist named glucagon-Cex has been designed, synthesized and crystallized. This peptide was highly soluble under physiological conditions and crystallized readily. The crystal diffracted X-rays to 2.2 Å resolution and the diffraction was consistent with space group P23, with unit-cell parameters a = b = c = 48.20 Å, α = β = γ = 90.0°. The crystals were suitable for a full structural determination to reveal the conformational differences between glucagon-Cex and the native hormone.

Perennial peanut (Arachis glabrata Benth.) contains polyphenol oxidase (PPO) and PPO substrates that can reduce post-harvest proteolysis.

Science.gov (United States)

Sullivan, Michael L; Foster, Jamie L

2013-08-15

Studies of perennial peanut (Arachis glabrata Benth.) suggest its hay and haylage have greater levels of rumen undegraded protein (RUP) than other legume forages such as alfalfa (Medicago sativa L.). Greater RUP can result in more efficient nitrogen utilization by ruminant animals with positive economic and environmental effects. We sought to determine whether, like red clover (Trifolium pretense L.), perennial peanut contains polyphenol oxidase (PPO) and PPO substrates that might be responsible for increased RUP. Perennial peanut extracts contain immunologically detectible PPO protein and high levels of PPO activity (>100 nkatal mg(-1) protein). Addition of caffeic acid (PPO substrate) to perennial peanut extracts depleted of endogenous substrates reduced proteolysis by 90%. Addition of phenolics prepared from perennial peanut leaves to extracts of either transgenic PPO-expressing or control (non-expressing) alfalfa showed peanut phenolics could reduce proteolysis >70% in a PPO-dependent manner. Two abundant likely PPO substrates are present in perennial peanut leaves including caftaric acid. Perennial peanut contains PPO and PPO substrates that together are capable of inhibiting post-harvest proteolysis, suggesting a possible mechanism for increased RUP in this forage. Research related to optimizing the PPO system in other forage crops will likely be applicable to perennial peanut. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Depression of hyperglycemic response to glucagon by parenteral lead administration in sheep

Energy Technology Data Exchange (ETDEWEB)

Brockman, R P

1978-01-01

The insulin and glucose responses to glucagon infusions (27 ..mu..g/hr) were determined in sheep before and after parenteral lead treatment (6 mg/kg intravenously). Glucose production was measured by primed continuous infusion of (6-/sup 3/H)glucose. Glucagon and insulin concentrations before and during glucagon infusions were not significantly different between lead treatment and control experiments. Lead administration did not affect the concentration or production of glucose in the preinfusion period. However, depressed hyperglycemia during glucagon infusion in lead treated experiments tended to be associated with decreased glucose production. The reduced glucogenic response to glucagon may be the result of reduced function of pyruvate carboxylase, a key hepatic gluconeogenic enzyme in sheep, from lead induced impairment of mitochondrial function. 21 references, 1 figure.

Glucagon-insulin interaction on fat cell metabolism using c14 glucose

International Nuclear Information System (INIS)

Zewail, M.A.; Nielsen, J.H.

1984-01-01

Glucagon is known to stimulate the lipolysis in isolated fat cells from young rats, but not in fat cells from old heavy rate (Manganiello 1972). Insulin is known to counteract the lipolytic effect and to stimulate the synthesis of fatty acids from glucose. However, little is known about the interaction between the two hormones on the glucose metabolism. Experiments based on the use of various inhibitors of lipolysis have however, clearly shown that glucagon can also stimulate the entry and overall oxidation of glucose by mechanism which is distinct from its lipolysis stimulating mechanism (M. Blecher et al. 1969). Fat cells from old heavy rats are known to be less responsive to both the lipogenic action of insulin and the lipolytic action of glucagon than fat cells from young lean rats (E.G. Hansen, Nielsen and Gliemann, 1974). The aim of the present study was to see how glucagon affects glucose metabolism in fat cells, and whether this effect was dependent on the lipolytic action of glucagon

Treatment of Aluminium Phosphide Poisoning with a Combination of Intravenous Glucagon, Digoxin and Antioxidant Agents

Directory of Open Access Journals (Sweden)

Zohreh Oghabian

2016-08-01

Full Text Available Aluminium phosphide (AlP is used to protect stored grains from rodents. It produces phosphine gas (PH3, a mitochondrial poison thought to cause toxicity by blocking the cytochrome c oxidase enzyme and inhibiting oxidative phosphorylation, which results in cell death. AlP poisoning has a high mortality rate among humans due to the rapid onset of cardiogenic shock and metabolic acidosis, despite aggressive treatment. We report a 21-yearold male who was referred to the Afzalipour Hospital, Kerman, Iran, in 2015 after having intentionally ingested a 3 g AlP tablet. He was successfully treated with crystalloid fluids, vasopressors, sodium bicarbonate, digoxin, glucagon and antioxidant agents and was discharged from the hospital six days after admission in good clinical condition. For the treatment of AlP poisoning, the combination of glucagon and digoxin with antioxidant agents should be considered. However, evaluation of further cases is necessary to optimise treatment protocols.

Andrographolide alleviates imiquimod-induced psoriasis in mice via inducing autophagic proteolysis of MyD88.

Science.gov (United States)

Shao, Fenli; Tan, Tao; Tan, Yang; Sun, Yang; Wu, Xingxin; Xu, Qiang

2016-09-01

Psoriasis is a chronic inflammatory skin disease with excessive activation of toll-like receptors (TLRs), which play important roles in developing psoriasis. Targeting TLR signaling remains a challenge for treating psoriasis. Here, we found that andrographolide (Andro), a small-molecule natural product, alleviated imiquimod- but not interleukin 23 (IL-23)-induced psoriasis in mice with reducing expressions of IL-23 and IL-1β in the skin. The improvement in imiquimod-induced psoriasis by Andro was not observed in microtubule-associated protein 1 light chain 3 beta (MAP1LC3B) knockout mice. Furthermore, Andro inhibited mRNA expressions of IL-23, IL-6 and IL-1β but not CD80 and CD86 in bone-marrow derived dendritic cells (BMDCs) treated with lipopolysaccharide (LPS) in a MAP1LC3B-dependent manner. In addition, Andro inhibited imiquimod-induced mRNA expressions of IL-23, IL-6, IL-1β, CD80 and CD86 in BMDCs from mice. Interestingly, Andro induced a degradation of myeloid differentiation factor 88 (MyD88) and blocked the recruitment of TNF receptor-associated factor 6 (TRAF6) to MyD88 upon LPS stimulation in BMDCs from mice. Blockade of autophagic proteolysis using NH4Cl or MAP1LC3B(-/-) BMDCs abolished the Andro-induced MyD88 degradation. In conclusion, Andro controls activation of MyD88-dependent cytokines and alleviates psoriasis in mice via inducing autophagic proteolysis of MyD88, which could be a novel strategy to treat psoriasis. Copyright © 2016 Elsevier Inc. All rights reserved.

Immobilization of trypsin on miniature incandescent bulbs for infrared-assisted proteolysis

Energy Technology Data Exchange (ETDEWEB)

Ge, Huimin; Bao, Huimin; Zhang, Luyan; Chen, Gang, E-mail: gangchen@fudan.edu.cn

2014-10-03

Highlights: • Trypsin was immobilized on miniature incandescent bulbs via chitosan coating. • The bulbs acted as enzymatic reactors and the generators of infrared radiation. • The bulb bioreactors were successfully employed in infrared-assisted proteolysis. • The proteolysis could accomplish within 5 min with high sequence coverages. - Abstract: A novel efficient proteolysis approach was developed based on trypsin-immobilized miniature incandescent bulbs and infrared (IR) radiation. Trypsin was covalently immobilized in the chitosan coating on the outer surface of miniature incandescent bulbs with the aid of glutaraldehyde. When an illuminated enzyme-immobilized bulb was immersed in protein solution, the emitted IR radiation could trigger and accelerate heterogeneous protein digestion. The feasibility and performance of the novel proteolysis approach were demonstrated by the digestion of hemoglobin (HEM), cytochrome c (Cyt-c), lysozyme (LYS), and ovalbumin (OVA) and the digestion time was significantly reduced to 5 min. The obtained digests were identified by MALDI-TOF-MS with the sequence coverages of 91%, 77%, 80%, and 52% for HEM, Cyt-c, LYS, and OVA (200 ng μL{sup −1} each), respectively. The suitability of the prepared bulb bioreactors to complex proteins was demonstrated by digesting human serum.

Plasma glucagon and glucose recovery after hypoglycemia

DEFF Research Database (Denmark)

Hilsted, J; Frandsen, Henrik Lund; Holst, Janett

1991-01-01

) and of isolated alpha-adrenergic blockade on hormonal responses to hypoglycemia and on blood glucose recovery after hypoglycemia in healthy subjects. Neither of the pharmacological blockades had any significant effects on plasma glucagon responses to hypoglycemia nor had they any effect on the rate of blood...... glucose recovery after hypoglycemia. We conclude that the autonomic nervous system has no major influence on the glucagon response to hypoglycemia in healthy man. Changes in autonomic nervous activity are not essential for blood glucose recovery after hypoglycemia in healthy man....

Glucagon releases Ca2+ from a FCCP-sensitive pool

International Nuclear Information System (INIS)

Kraus-Friedmann, N.

1986-01-01

The effects of physiological levels of glucagon on Ca 2+ efflux were examined in the perfused rat liver. Two methods were used to estimate Ca 2+ efflux: (1) prior labeling of the Ca 2+ pools with 45 Ca 2+ , and (2) measurement of perfusate Ca 2+ with atomic absorption. According to both methods, glucagon administration at the physiological level evoked Ca 2+ release. In order to identify the hormone-sensitive Ca 2+ pool, a method employed by several laboratories was used. In this method, mitochondrial Ca 2+ is released by FCCP, (carbonyl-cyanide 4 (trifluoro/methoxy) phenylhydrazone), a mitochondrial uncoupler. The effect of hormones on Ca 2+ release after such uncoupler administration is measured. A decreased release is taken as an indication that the pool is entirely or partially mitochondrial. FCCP released 90 +/- 29 nmoles Ca 2+ /gr wet liver. Glucagon (5 x 10 -9 M) released 107 +/- 45 nmoles Ca 2+ /gr wet liver before and 26 +/- 9 nmoles Ca 2+ /gr wet liver after FCCP. These data indicate that glucagon releases Ca 2+ mostly from the mitochondria

Role of glucagon in intestinal hyperemia associated with early experimental diabetes mellitus

International Nuclear Information System (INIS)

Yrle, L.F.; Smith, J.K.; Benoit, J.N.; Granger, D.N.; Korthuis, R.J.

1988-01-01

The role of glucagon as a blood-borne mediator of the intestinal hyperemia associated with experimental diabetes mellitus was assessed in anesthetized fasted (18-24 h) rats 4 wk after the administration of streptozotocin or its vehicle. Selective removal of pancreatic glucagon from the circulation was accomplished by the intravenous administration of a highly specific glucagon antiserum. Blood flow to the gastrointestinal tract and kidneys was measured with radioactive microspheres using the reference sample technique. Blood flows were increased by at least 60% in each segment of the gastrointestinal tract of diabetic animals compared with control rats. Glucagon antiserum had no effect on blood flows in the gastrointestinal tract of control animals. However, the antiserum produced a significant reduction in blood flow to the stomach (26%), duodenum (25%), jejunum (12%), and kidneys (16%) in diabetic rats. There was no change in blood flow to the ileum or colon of diabetic animals with antiserum administration. The results of this study support the hypothesis that glucagon mediates a portion of the hyperemia noted in the stomach, duodenum, and jejunum. However, glucagon does not appear to play a role in the genesis of the hyperemia noted in more distal segments of the gastrointestinal tract (ileum and colon). A possible role for glucagon in the maintenance of renal blood flow in diabetic rats is suggested

Glucagon infusion increases rate of purine synthesis de novo in rat liver

International Nuclear Information System (INIS)

Itakura, Mitsuo; Maeda, Noriaki; Tsuchiya, Masami; Yamashita, Kamejiro

1987-01-01

Based on the parallel increases of glucagon, the second peak of hepatic cAMP, and the rate of purine synthesis de novo in the prereplicative period in regenerating rate liver after a 70% hepatectomy, it was hypothesized that glucagon is responsible for the increased rate of purine synthesis de novo. To test this hypothesis, the effect of glucagon or dibutyryl cAMP infusion on the rate of purine synthesis de novo in rat liver was studied. Glucagon infusion but not insulin or glucose infusion increased the rate of purine synthesis de novo, which was assayed by [ 14 C]glycine or [ 14 C]formate incorporation, by 2.7- to 4.3-fold. Glucagon infusion increased cAMP concentrations by 4.9-fold and 5-phosphoribosyl-1-pyrophosphate concentrations by 1.5-fold in liver but did not change the specific activity of amidophosphoribosyltransferase or purine ribonucleotide concentrations. Dibutyryl cAMP infusion also increased the rate of purine synthesis de novo by 2.2- to 4.0-fold. Because glucagon infusion increased the rate of purine synthesis de novo in the presence of unchanged purine ribonucleotide concentrations, it is concluded that glucagon after infusion or in animals after a 70% hepatectomy is playing an anabolic role to increase the rate of purine synthesis de novo by increasing cAMP and 5-phosphoribosyl-1-pyrophosphate concentrations

Production of carboxy-terminal specific antiserum against glucagon

International Nuclear Information System (INIS)

Liu Yibing; Han Shiquan

1993-01-01

To produce carboxy-terminal specific antisera against glucagon was coupled mainly via its amino terminal histidine to thyroglobulin, using the amino group reactive pentandiol at pH 7.0 for the conjugation procedure. After repeated immunization of guinea pigs and rabbits, the antisera were obtained. The titer of guinea pig antiserum against glucagon was 1:3000-1:35000 and affinity constant was 9.3 x 10 10 -11.4 x 10 10 l · mol -1 . There were no cross reaction with GIP, INS, Copeptide and gastrin. The titer of rabbit antiserum against glucagon was 1:900-1:9000 and affinity constant was 0.36 x 10 10 -3.9 x 10 10 l · mol -1 . There were no cross reaction with INS, C-peptide and gastrin. The cross reaction with GIP was 0.02%

Protein trafficking and maturation regulate intramembrane proteolysis.

Science.gov (United States)

Morohashi, Yuichi; Tomita, Taisuke

2013-12-01

Intramembrane-cleaving proteases (I-CLiPs) are membrane embedded proteolytic enzymes. All substrates identified so far are also membrane proteins, involving a number of critical cellular signaling as well as human diseases. After synthesis and assembly at the endoplasmic reticulum, membrane proteins are exported to the Golgi apparatus and transported to their sites of action. A number of studies have revealed the importance of the intracellular membrane trafficking in i-CLiP-mediated intramembrane proteolysis, not only for limiting the unnecessary encounter between i-CLiPs and their substrate but also for their cleavage site preference. In this review, we will discuss recent advances in our understanding of how each i-CLiP proteolysis is regulated by intracellular vesicle trafficking. This article is part of a Special Issue entitled: Intramembrane Proteases. Copyright © 2013 Elsevier B.V. All rights reserved.

The dipeptidyl peptidase 4 inhibitor vildagliptin does not accentuate glibenclamide-induced hypoglycemia but reduces glucose-induced glucagon-like peptide 1 and gastric inhibitory polypeptide secretion

DEFF Research Database (Denmark)

El-Ouaghlidi, Andrea; Rehring, Erika; Holst, Jens Juul

2007-01-01

BACKGROUND/AIMS: Inhibition of dipeptidyl peptidase 4 by vildagliptin enhances the concentrations of the active form of the incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). The present study asked whether vildagliptin accentuates glibenclamide-induced hy...

Pancreatic α-cell hyperplasia and hyperglucagonemia due to a mutation of the glucagon

DEFF Research Database (Denmark)

Larger, Etienne; Albrechtsen, Nicolai Jacob Wewer; Hansen, L.H.

2016-01-01

Glucagon stimulates hepatic glucose production by activating specific glucagon receptors in the liver, which in turn increase hepatic glycogenolysis as well as gluconeogenesis and ureagenesis from amino acids. Conversely, glucagon secretion is regulated by concentrations of glucose and amino acids...... to hyperglucagonemia and α-cell hyperplasia, as well as elevated plasma amino acid levels. Together with the glucagon-induced hypoaminoacidemia in glucagonoma patients, our case supports recent suggestions that amino acids may provide the feedback link between the liver and the pancreatic α-cells....

CT colonography: colonic distention improved by dual positioning but not intravenous glucagon

International Nuclear Information System (INIS)

Morrin, Martina M.; Keogan, Mary T.; Kruskal, Jonathan B.; Yam, Chun-Shan; Raptopoulos, Vassilios; Farrell, Richard J.

2002-01-01

The aim of this study was to determine whether intravenous (IV) glucagon and dual positioning administered prior to CT colonography enhances colonic distention. We assessed the effect of dual positioning and IV glucagon on colonic distention in 96 patients who underwent CT colonography examinations. The CT colonography was performed in both supine and prone positions. Seventy-four patients received glucagon (1 mg i.v.) immediately prior to CT scanning and 22 patients did not. The bowel was divided into ten segments and colonic distention was scored by two radiologists in the supine, prone, and combined supine/prone positions using a five-point scale: 1=collapsed; 2=poorly visualized; ≥3=adequate distention; 4=entire segment visualized and well distended; 5=excellent distention. A combined segmental and overall supine/prone distention score was calculated based on the sum of the mean score for each position. There was no significant difference in the degree of colonic distention between patients who received glucagon and those who did not [supine/prone distention score (mean±SE): 3.63±0.2 vs 3.85±0.2; p=n.s.]. The degree of colonic distention was greater in the prone position in both the glucagon (3.87±0.2 vs 3.38±0.2; p<0.05) and non-glucagon groups (4.01±0.2 vs 3.69±0.2; p=N.S.) particularly in the proximal colon. There was almost perfect agreement between both radiologists in their scoring of colonic distention on a per-patient basis (k=0.9; p<0.001). Of 1480 bowel segments, 1261 (85.2%) were adequately distended in the glucagon group compared with 370 of 440 bowel segments (84%) in the non-glucagon group (p=n.s.) Colonic distention at CT colonography is improved by dual positioning but not by the administration of intravenous glucagon. While our results suggest that other smooth muscle relaxants, including butyl scopolamine, may only have a limited role in improving colonic distention in CT colonography, further studies are required. (orig.)

Proteolysis produced within biofilms of bacterial isolates from raw milk tankers.

Science.gov (United States)

Teh, Koon Hoong; Flint, Steve; Palmer, Jon; Andrewes, Paul; Bremer, Phil; Lindsay, Denise

2012-06-15

In this study, six bacterial isolates that produced thermo-resistant enzymes isolated from the internal surfaces of raw milk tankers were evaluated for their ability to produce proteolysis within either single culture biofilms or co-culture biofilms. Biofilms were formed in an in vitro model system that simulated the upper internal surface of a raw milk tanker during a typical summer's day of milk collection in New Zealand. The bacterial isolates were further evaluated for their ability to form biofilms at 25, 30 and 37°C. Mutual and competitive effects were observed in some of the co-culture biofilms, with all isolates being able to form biofilms in either single culture or co-culture at the three temperatures. The proteolysis was also evaluated in both biofilms and corresponding planktonic cultures. The proteolysis per cell decreased as the temperature of incubation (20-37°C) increased. Furthermore, mutualistic interactions in terms of proteolysis were observed when cultures were grown as co-culture biofilms. This is the first study to show that proteolytic enzymes can be produced in biofilms on the internal surfaces of raw milk tankers. This has important implications for the cleaning and the temperature control of raw milk transport tankers. Copyright © 2012 Elsevier B.V. All rights reserved.

Glucagon-like peptides GLP-1 and GLP-2, predicted products of the glucagon gene, are secreted separately from pig small intestine but not pancreas

DEFF Research Database (Denmark)

Holst, J J; Poulsen, Steen Seier

1986-01-01

We developed specific antibodies and RIAs for glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), two predicted products of the glucagon gene, and studied the occurrence, nature, and secretion of immunoreactive GLP-1 and GLP-2 in pig pancreas and small intestine. Immunoreactive GLP-1 and GLP-2 were...

Production of carboxy-terminal specific antiserum against glucagon

Energy Technology Data Exchange (ETDEWEB)

Yibing, Liu; Shiquan, Han [Academia Sinica, Beijing, BJ (China). Inst. of Atomic Energy

1993-02-01

To produce carboxy-terminal specific antisera against glucagon was coupled mainly via its amino terminal histidine to thyroglobulin, using the amino group reactive pentandiol at pH 7.0 for the conjugation procedure. After repeated immunization of guinea pigs and rabbits, the antisera were obtained. The titer of guinea pig antiserum against glucagon was 1:3000-1:35000 and affinity constant was 9.3 x 10[sup 10]-11.4 x 10[sup 10] l [center dot] mol[sup -1]. There were no cross reaction with GIP, INS, Copeptide and gastrin. The titer of rabbit antiserum against glucagon was 1:900-1:9000 and affinity constant was 0.36 x 10[sup 10]-3.9 x 10[sup 10] l [center dot] mol[sup -1]. There were no cross reaction with INS, C-peptide and gastrin. The cross reaction with GIP was 0.02%.

Ubiquitin-mediated proteolysis in Xenopus extract.

Science.gov (United States)

McDowell, Gary S; Philpott, Anna

2016-01-01

The small protein modifier, ubiquitin, can be covalently attached to proteins in the process of ubiquitylation, resulting in a variety of functional outcomes. In particular, the most commonly-associated and well-studied fate for proteins modified with ubiquitin is their ultimate destruction: degradation by the 26S proteasome via the ubiquitin-proteasome system, or digestion in lysosomes by proteolytic enzymes. From the earliest days of ubiquitylation research, a reliable and versatile "cell-in-a-test-tube" system has been employed in the form of cytoplasmic extracts from the eggs and embryos of the frog Xenopus laevis. Biochemical studies of ubiquitin and protein degradation using this system have led to significant advances particularly in the study of ubiquitin-mediated proteolysis, while the versatility of Xenopus as a developmental model has allowed investigation of the in vivo consequences of ubiquitylation. Here we describe the use and history of Xenopus extract in the study of ubiquitin-mediated protein degradation, and highlight the versatility of this system that has been exploited to uncover mechanisms and consequences of ubiquitylation and proteolysis.

Disruption of glucagon receptor signaling causes hyperaminoacidemia exposing a possible liver - alpha-cell axis

DEFF Research Database (Denmark)

Galsgaard, Katrine D; Winther-Sørensen, Marie; Ørskov, Cathrine

2018-01-01

Glucagon secreted from the pancreatic alpha-cells is essential for regulation of blood glucose levels. However, glucagon may play an equally important role in the regulation of amino acid metabolism by promoting ureagenesis. We hypothesized that disruption of glucagon receptor signaling would lead...

Radio-immunoassays for glucagon-like peptides 1 and 2 (GLP-1 and GLP-2)

DEFF Research Database (Denmark)

Orskov, C; Holst, J J

1987-01-01

Gene-sequencing studies have shown that the glucagon precursor contains two additional glucagon-like sequences, the so-called glucagon-like peptides 1 and 2 (GLP-1 and GLP-2). We developed radio-immunoassays against synthetic peptides corresponding to these sequences. Antisera were raised in rabb...

Glucagon-like peptide-2, but not glucose-dependent insulinotropic polypeptide, stimulates glucagon release in patients with type 1 diabetes

DEFF Research Database (Denmark)

Christensen, Mikkel; Knop, Filip K; Vilsbøll, Tina

2010-01-01

This study investigated the glucagon-releasing properties of the hormones glucagon-like peptide-2 (GLP-2) and glucose-dependent insulinotropic polypeptide (GIP) in 8 patients with type 1 diabetes mellitus (T1DM) without paracrine intraislet influence of insulin (C-peptide negative following a 5 g...... intravenous arginine stimulation; on study days only treated with basal insulin substitution). On 3 study days, 180-minute two-step glucose clamps were performed. Plasma glucose (PG) was clamped at fasting values, with a mean of 7.4+/-0.5 mM in the first 90 min (period 1) and raised 1.5 times the fasting...

PK/PD modelling of glucose-insulin-glucagon dynamics in healthy dogs after a subcutaneous bolus administration of native glucagon or a novel glucagon analogue

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Møller, Jan Kloppenborg; Boye Knudsen, Carsten

by Zealand Pharma A/S. Research Design and Methods We expanded a physiological model of endogenous glucose production with multiplicative effects of insulin and glucagon and combined it with the Hovorka glucoregulatory model. We used a Bayesian framework to perform multidimensional MAP estimation of model...

Potentiation of glucose-induced insulin release in islets by desHis1[Glu9]glucagon amide

DEFF Research Database (Denmark)

Kofod, Hans; Unson, C G; Merrifield, R B

1988-01-01

Glucagon and secretin and some of their hybrid analogs potentiate glucose-induced release of insulin from isolated mouse pancreatic islets. It was recently shown that the synthetic glucagon analog, desHis1[Glu9]glucagon amide, does not stimulate the formation of cyclic adenosine monophosphate...... in the rat hepatocyte membrane, but binds well to the glucagon receptor and is a good competitive antagonist of glucagon. In the present study the effect of this analog on isolated islets was examined. desHis1-[Glu9]glucagon amide at 3 x 10(-7) M, in the presence of 0.01 M D-glucose, increased the release...

Opposite Regulation of Ghrelin and Glucagon-like Peptide-1 by Metabolite G-Protein-Coupled Receptors

DEFF Research Database (Denmark)

Engelstoft, M S; Schwartz, T W

2016-01-01

Gut hormones send information about incoming nutrients to the rest of the body and thereby control many aspects of metabolism. The secretion of ghrelin and glucagon-like protein (GLP)-1, two hormones with opposite secretory patterns and opposite actions on multiple targets, is controlled by a lim......Gut hormones send information about incoming nutrients to the rest of the body and thereby control many aspects of metabolism. The secretion of ghrelin and glucagon-like protein (GLP)-1, two hormones with opposite secretory patterns and opposite actions on multiple targets, is controlled...... by a limited number of G-protein coupled receptors (GPCRs); half of which recognize and bind dietary nutrient metabolites, metabolites generated by gut microbiota, and metabolites of the host's intermediary metabolism. Most metabolite GPCRs controlling ghrelin secretion are inhibitory, whereas all metabolite...... receptors controlling GLP-1 secretion are stimulatory. This dichotomy in metabolite sensor function, which is obtained through a combination of differential expression and cell-dependent signaling bias, offers pharmacological targets to stimulate GLP-1 and inhibit ghrelin through the same mechanism....

Molecular characterization of a proteolysis-resistant lipase from Bacillus pumilus SG2

Directory of Open Access Journals (Sweden)

R. Sangeetha

2014-06-01

Full Text Available Proteolysis-resistant lipases can be well exploited by industrial processes which employ both lipase and protease as biocatalysts. A proteolysis resistant lipase from Bacillus pumilus SG2 was isolated, purified and characterized earlier. The lipase was resistant to native and commercial proteases. In the present work, we have characterized the lip gene which encodes the proteolysis-resistant lipase from Bacillus pumilus SG2. The parameters and structural details of lipase were analysed. The lip gene consisted of 650 bp. The experimental molecular weight of SG2 lipase was nearly double that of its theoretical molecular weight, thus suggesting the existence of the functional lipase as a covalent dimer. The proteolytic cleavage sites of the lipase would have been made inaccessible by dimerisation, thus rendering the lipase resistant to protease.

The changing face of glucagon fibrillation: Structural polymorphism and conformational imprinting

DEFF Research Database (Denmark)

Pedersen, J.S.; Dikov, D.; Flink, J.L.

2006-01-01

concentration) appear less thermostable than those formed under more challenging conditions (high temperatures, low glucagon or low salt concentrations). Properties of preformed fibrils used for seeding are inherited in a prion-like manner. Thus, we conclude that the structure of fibrils formed by glucagon...

JNK signaling pathway regulates sorbitol-induced Tau proteolysis and apoptosis in SH-SY5Y cells by targeting caspase-3.

Science.gov (United States)

Olivera Santa-Catalina, Marta; Caballero Bermejo, Montaña; Argent, Ricardo; Alonso, Juan C; Centeno, Francisco; Lorenzo, María J

2017-12-15

Growing evidence suggests that Diabetes Mellitus increases the risk of developing Alzheimer's disease. It is well known that hyperglycemia, a key feature of Diabetes Mellitus, may induce plasma osmolarity disturbances. Both hyperglycemia and hyperosmolarity promote the altered post-translational regulation of microtubule-associated protein Tau. Interestingly, abnormal hyperphosphorylation and cleavage of Tau have been proven to lead to the genesis of filamentous structures referred to as neurofibrillary tangles, the main pathological hallmark of Alzheimer's disease. We have previously described that hyperosmotic stress induced by sorbitol promotes Tau proteolysis and apoptosis in SH-SY5Y cells via caspase-3 activation. In order to gain insights into the regulatory mechanisms of such processes, in this work we explored the intracellular signaling pathways that regulate these events. We found that sorbitol treatment significantly enhanced the activation of conventional families of MAPK in SH-SY5Y cells. Tau proteolysis was completely prevented by JNK inhibition but not affected by either ERK1/2 or p38 MAPK blockade. Moreover, inhibition of JNK, but not ERK1/2 or p38 MAPK, efficiently prevented sorbitol-induced apoptosis and caspase-3 activation. In summary, we provide evidence that JNK signaling pathway is an upstream regulator of hyperosmotic stress-induced Tau cleavage and apoptosis in SH-SY5Y through the control of caspase-3 activation. Copyright © 2017 Elsevier Inc. All rights reserved.

Conjoint regulation of glucagon concentrations via plasma insulin and glucose in dairy cows.

Science.gov (United States)

Zarrin, M; Wellnitz, O; Bruckmaier, R M

2015-04-01

Insulin and glucagon are glucoregulatory hormones that contribute to glucose homeostasis. Plasma insulin is elevated during normoglycemia or hyperglycemia and acts as a suppressor of glucagon secretion. We have investigated if and how insulin and glucose contribute to the regulation of glucagon secretion through long term (48 h) elevated insulin concentrations during simultaneous hypoglycemia or euglycemia in mid-lactating dairy cows. Nineteen Holstein dairy cows were randomly assigned to 3 treatment groups: an intravenous insulin infusion (HypoG, n = 5) to decrease plasma glucose concentrations (2.5 mmol/L), a hyperinsulinemic-euglycemic clamp to study effects of insulin at simultaneously normal glucose concentrations (EuG, n = 6) and a 0.9% saline infusion (NaCl, n = 8). Plasma glucose was measured at 5-min intervals, and insulin and glucose infusion rates were adjusted accordingly. Area under the curve of hourly glucose, insulin, and glucagon concentrations on day 2 of infusion was evaluated by analysis of variance with treatments as fixed effect. Insulin infusion caused an increase of plasma insulin area under the curve (AUC)/h in HypoG (41.9 ± 8.1 mU/L) and EuG (57.8 ± 7.8 mU/L) compared with NaCl (13.9 ± 1.1 mU/L; P insulin infusion induces elevated glucagon concentrations during hypoglycemia, although the same insulin infusion reduces glucagon concentrations at simultaneously normal glucose concentrations. Thus, insulin does not generally have an inhibitory effect on glucagon concentrations. If simultaneously glucose is low and insulin is high, glucagon is upregulated to increase glucose availability. Therefore, insulin and glucose are conjoint regulatory factors of glucagon concentrations in dairy cows, and the plasma glucose status is the key factor to decide if its concentrations are increased or decreased. This regulatory effect can be important for the maintenance of glucose homeostasis if insulin secretion is upregulated by other factors than high

A second glucagon in the pancreatic islets of the daddy sculpin Cottus scorpius.

Science.gov (United States)

Cutfield, S M; Cutfield, J F

1993-09-01

The peptide hormone glucagon has been isolated from the islet tissue (Brockmann bodies) of the teleost Cottus scorpius (daddy sculpin) and sequenced. The sequence is HSEGTSNDYSKYLEDRKAQDFVQWLMNN differing at four positions from the glucagon found earlier in the same species by Conlon and coworkers (1987b, Eur. J. Biochem, 164, 117-122). Thus sculpin, in common with anglerfish, possesses two distinct glucagons. Comparative sequence data are presented as a phylogenetic tree.

Impact of exogenous hyperglucagonemia on postprandial concentrations of gastric inhibitory polypeptide and glucagon-like peptide-1 in humans

DEFF Research Database (Denmark)

Meier, Juris J; Ritter, Peter R; Jacob, Alexandra

2010-01-01

Postprandial secretion of glucagon-like peptide 1 (GLP-1) has been found diminished in some patients with type 2 diabetes mellitus (T2DM) and high glucagon concentrations. We examined the effects of exogenous glucagon on the release of incretin hormones.......Postprandial secretion of glucagon-like peptide 1 (GLP-1) has been found diminished in some patients with type 2 diabetes mellitus (T2DM) and high glucagon concentrations. We examined the effects of exogenous glucagon on the release of incretin hormones....

Glucagon Decreases IGF-1 Bioactivity in Humans, Independently of Insulin, by Modulating Its Binding Proteins.

Science.gov (United States)

Sarem, Zeinab; Bumke-Vogt, Christiane; Mahmoud, Ayman M; Assefa, Biruhalem; Weickert, Martin O; Adamidou, Aikatarini; Bähr, Volker; Frystyk, Jan; Möhlig, Matthias; Spranger, Joachim; Lieske, Stefanie; Birkenfeld, Andreas L; Pfeiffer, Andreas F H; Arafat, Ayman M

2017-09-01

Depending on its lipolytic activity, glucagon plays a promising role in obesity treatment. Glucagon-induced growth hormone (GH) release can promote its effect on lipid metabolism, although the underlying mechanisms have not been well-defined. The present study highlights the glucagon effect on the GH/insulinlike growth factor 1 (IGF-1)/IGF-binding protein (IGFBP) axis in vivo and in vitro, taking into consideration insulin as a confounding factor. In a double-blind, placebo-controlled study, we investigated changes in GH, IGFBP, and IGF-1 bioactivity after intramuscular glucagon administration in 13 lean controls, 11 obese participants, and 13 patients with type 1 diabetes mellitus (T1DM). The effect of glucagon on the transcription factor forkhead box protein O1 (FOXO1) translocation, the transcription of GH/IGF-1 system members, and phosphorylation of protein kinase B (Akt) was further investigated in vitro. Despite unchanged total IGF-1 and IGFBP-3 levels, glucagon decreased IGF-1 bioactivity in all study groups by increasing IGFBP-1 and IGFBP-2. The reduction in IGF-1 bioactivity occurred before the glucagon-induced surge in GH. In contrast to the transient increase in circulating insulin in obese and lean participants, no change was observed in those with T1DM. In vitro, glucagon dose dependently induced a substantial nuclear translocation of FOXO1 in human osteosarcoma cells and tended to increase IGFBP-1 and IGFBP-2 gene expression in mouse primary hepatocytes, despite absent Akt phosphorylation. Our data point to the glucagon-induced decrease in bioactive IGF-1 levels as a mechanism through which glucagon induces GH secretion. This insulin-independent reduction is related to increased IGFBP-1 and IGFBP-2 levels, which are most likely mediated via activation of the FOXO/mTOR (mechanistic target of rapamycin) pathway. Copyright © 2017 Endocrine Society

Structure of the human glucagon class B G-protein-coupled receptor

NARCIS (Netherlands)

Siu, F.Y.; He, M.; de Graaf, C.; Yang, D; Zhang, Z.; Zhou, C.; Han, G.W.; Xu, Q.; Wacker, D.; Joseph, J.S.; Wei, Liu; Lau, J.F.; Cherezov, V.; Katritch, V; Wang, M.W.; Stevens, R.C.

2013-01-01

Binding of the glucagon peptide to the glucagon receptor (GCGR) triggers the release of glucose from the liver during fasting; thus GCGR plays an important role in glucose homeostasis. Here we report the crystal structure of the seven transmembrane helical domain of human GCGR at 3.4 Å resolution,

New concepts in molecular imaging: non-invasive MRI spotting of proteolysis using an Overhauser effect switch.

Directory of Open Access Journals (Sweden)

Philippe Mellet

Full Text Available Proteolysis, involved in many processes in living organisms, is tightly regulated in space and time under physiological conditions. However deregulation can occur with local persistent proteolytic activities, e.g. in inflammation, cystic fibrosis, tumors, or pancreatitis. Furthermore, little is known about the role of many proteases, hence there is a need of new imaging methods to visualize specifically normal or disease-related proteolysis in intact bodies.In this paper, a new concept for non invasive proteolysis imaging is proposed. Overhauser-enhanced Magnetic Resonance Imaging (OMRI at 0.2 Tesla was used to monitor the enzymatic hydrolysis of a nitroxide-labeled protein. In vitro, image intensity switched from 1 to 25 upon proteolysis due to the associated decrease in the motional correlation time of the substrate. The OMRI experimental device used in this study is consistent with protease imaging in mice at 0.2 T without significant heating. Simulations show that this enzymatic-driven OMRI signal switch can be obtained at lower frequencies suitable for larger animals or humans.The method is highly sensitive and makes possible proteolysis imaging in three dimensions with a good spatial resolution. Any protease could be targeted specifically through the use of taylor-made cleavable macromolecules. At short term OMRI of proteolysis may be applied to basic research as well as to evaluate therapeutic treatments in small animal models of experimental diseases.

Loss of inverse relationship between pulsatile insulin and glucagon secretion in patients with type 2 diabetes

DEFF Research Database (Denmark)

Menge, Björn A; Grüber, Lena; Jørgensen, Signe M

2011-01-01

In patients with type 2 diabetes, glucagon levels are often increased. Furthermore, pulsatile secretion of insulin is disturbed in such patients. Whether pulsatile glucagon secretion is altered in type 2 diabetes is not known.......In patients with type 2 diabetes, glucagon levels are often increased. Furthermore, pulsatile secretion of insulin is disturbed in such patients. Whether pulsatile glucagon secretion is altered in type 2 diabetes is not known....

Role of Glucagon in Catabolism and Muscle Wasting of Critical Illness and Modulation by Nutrition

DEFF Research Database (Denmark)

Thiessen, Steven E; Derde, Sarah; Derese, Inge

2017-01-01

of glucagon and its metabolic role during critical illness is lacking. OBJECTIVES: To evaluate whether macronutrient infusion can suppress plasma glucagon during critical illness and study the role of illness-induced glucagon abundance in the disturbed glucose, lipid, and amino acid homeostasis and in muscle...... wasting during critical illness. METHODS: In human and mouse studies, we infused macronutrients and manipulated glucagon availability up and down to investigate its acute and chronic metabolic role during critical illness. MEASUREMENTS AND MAIN RESULTS: In critically ill patients, infusing glucose...

High-fidelity Glucagon-CreER mouse line generated by CRISPR-Cas9 assisted gene targeting

Directory of Open Access Journals (Sweden)

Amanda M. Ackermann

2017-03-01

Full Text Available Objective: α-cells are the second most prominent cell type in pancreatic islets and are responsible for producing glucagon to increase plasma glucose levels in times of fasting. α-cell dysfunction and inappropriate glucagon secretion occur in both type 1 and type 2 diabetes. Thus, there is growing interest in studying both normal function and pathophysiology of α-cells. However, tools to target gene ablation or activation specifically of α-cells have been limited, compared to those available for β-cells. Previous Glucagon-Cre and Glucagon-CreER transgenic mouse lines have suffered from transgene silencing, and the only available Glucagon-CreER “knock-in” mouse line results in glucagon haploinsufficiency, which can confound the interpretation of gene deletion analyses. Therefore, we sought to develop a Glucagon-CreERT2 mouse line that would maintain normal glucagon expression and would be less susceptible to transgene silencing. Methods: We utilized CRISPR-Cas9 technology to insert an IRES-CreERT2 sequence into the 3′ UTR of the Glucagon (Gcg locus in mouse embryonic stem cells (ESCs. Targeted ESC clones were then injected into mouse blastocysts to obtain Gcg-CreERT2 mice. Recombination efficiency in GCG+ pancreatic α-cells and glucagon-like peptide 1 positive (GLP1+ enteroendocrine L-cells was measured in Gcg-CreERT2;Rosa26-LSL-YFP mice injected with tamoxifen during fetal development and adulthood. Results: Tamoxifen injection of Gcg-CreERT2;Rosa26-LSL-YFP mice induced high recombination efficiency of the Rosa26-LSL-YFP locus in perinatal and adult α-cells (88% and 95%, respectively, as well as in first-wave fetal α-cells (36% and adult enteroendocrine L-cells (33%. Mice homozygous for the Gcg-CreERT2 allele were phenotypically normal. Conclusions: We successfully derived a Gcg-CreERT2 mouse line that expresses CreERT2 in pancreatic α-cells and enteroendocrine L-cells without disrupting preproglucagon gene expression. These mice

Physiological regulation of epithelial sodium channel by proteolysis

DEFF Research Database (Denmark)

Svenningsen, Per; Friis, Ulla G; Bistrup, Claus

2011-01-01

PURPOSE OF REVIEW: Activation of epithelial sodium channel (ENaC) by proteolysis appears to be relevant for day-to-day physiological regulation of channel activity in kidney and other epithelial tissues. Pathophysiogical, proteolytic activation of ENaC in kidney has been demonstrated in proteinuric...

Dual-hormone treatment with insulin and glucagon in patients with type 1 diabetes

DEFF Research Database (Denmark)

Reiband, H K; Schmidt, S; Ranjan, Ajenthen

2015-01-01

Intensive insulin treatment in type 1 diabetes reduces the incidence and slows the progression of microvascular and macrovascular complications; however, it is associated with an increased risk of hypoglycaemia and weight gain. In this review, we propose dual-hormone treatment with insulin...... and glucagon as a method for achieving near normalization of blood glucose levels without increasing hypoglycaemia frequency and weight gain. We briefly summarize glucagon pathophysiology in type 1 diabetes as well as the current applications of glucagon for the treatment of hypoglycaemia. Until now, the use...... of glucagon has been limited by the need for reconstitution immediately before use, because of instability of the available compounds; however, stabile compounds are soon to be launched and will render long-term intensive dual-hormone treatment in type 1 diabetes possible....

Glucagon and Amino Acids Are Linked in a Mutual Feedback Cycle

DEFF Research Database (Denmark)

Holst, Jens J; Wewer Albrechtsen, Nicolai J; Pedersen, Jens

2017-01-01

; neither condition is necessarily associated with disturbed glucose metabolism. In glucagonoma patients, amino acid turnover and ureagenesis are greatly accelerated, and low plasma amino acid levels are probably at least partly responsible for the necrolytic migratory erythema, which resolves after amino...... acid administration. In patients with receptor mutations (and in knockout mice), pancreatic swelling is due to α-cell hyperplasia with gross hypersecretion of glucagon, which according to recent groundbreaking research may result from elevated amino acid levels. Additionally, solid evidence indicates...... that ureagenesis, and thereby amino acid levels, is critically controlled by glucagon. Together, this constitutes a complete endocrine system; feedback regulation involving amino acids regulates α-cell function and secretion, while glucagon, in turn, regulates amino acid turnover....

Increased lipolysis and energy expenditure in a mouse model with severely impaired glucagon secretion.

Directory of Open Access Journals (Sweden)

Phing-How Lou

Full Text Available BACKGROUND: Secretion of insulin and glucagon is triggered by elevated intracellular calcium levels. Although the precise mechanism by which the calcium signal is coupled to insulin and glucagon granule exocytosis is unclear, synaptotagmin-7 has been shown to be a positive regulator of calcium-dependent insulin and glucagon secretion, and may function as a calcium sensor for insulin and glucagon granule exocytosis. Deletion of synaptotagmin-7 leads to impaired glucose-stimulated insulin secretion and nearly abolished Ca(2+-dependent glucagon secretion in mice. Under non-stressed resting state, however, synaptotagmin-7 KO mice exhibit normal insulin level but severely reduced glucagon level. METHODOLOGY/PRINCIPAL FINDINGS: We studied energy expenditure and metabolism in synaptotagmin-7 KO and control mice using indirect calorimetry and biochemical techniques. Synaptotagmin-7 KO mice had lower body weight and body fat content, and exhibited higher oxygen consumption and basal metabolic rate. Respiratory exchange ratio (RER was lower in synaptotagmin-7 KO mice, suggesting an increased use of lipid in their energy production. Consistent with lower RER, gene expression profiles suggest enhanced lipolysis and increased capacity for fatty acid transport and oxidation in synaptotagmin-7 KO mice. Furthermore, expression of uncoupling protein 3 (UCP3 in skeletal muscle was approximately doubled in the KO mice compared with control mice. CONCLUSIONS: These results show that the lean phenotype in synaptotagmin-7 KO mice was mostly attributed to increased lipolysis and energy expenditure, and suggest that reduced glucagon level may have broad influence on the overall metabolism in the mouse model.

The long-acting somatostatin analogue octreotide alleviates symptoms by reducing posttranslational conversion of prepro-glucagon to glucagon in a patient with malignant glucagonoma, but does not prevent tumor growth

NARCIS (Netherlands)

F. Jockenhövel (F.); S. Lederbogen (S.); T. Olbricht (T.); H. Schmidt-Gayk (H.); E.P. Krenning (Eric); S.W.J. Lamberts (Steven); D. Reinwein (D.)

1994-01-01

textabstractA 52-year-old female with metastatic glucagonoma secreting glucagon and chromogranin A was treated with the somatostatin analogue octreotide for 2 years without any additional tumor-reducing interventions. Before therapy plasma glucagon was above 8 μg/l (normal <0.2) and within 2 days 3

The effect of short-term glucagon infusion on kidney function in normal man

DEFF Research Database (Denmark)

Parving, H H; Noer, J; Kehlet, H

1977-01-01

Kidney function was studied in six normal males before and during a 2 h glucagon (10 ng/kg/min) infusion. The following variables were determined during each 20 min clearance period; glomerular filtration rate (GFR), renal plasma-flow (RPF) , filtration fraction (FF), urinary albumin and beta2......-microglobulin-excretion rates. Glucagon infusion resulted in a fourfold increase in plasma glucagon concentration. The infusion induced a significant increase in GFR (+9%), FF (+9%) and urinary beta2-microglobulin excretion rate (+32%), (p less than 0.01). RPF and urinary albumin excretion rates were...

Chemical and proteolysis-derived changes during long-term storage of lactose-hydrolyzed ultrahigh-temperature (UHT) milk.

Science.gov (United States)

Jansson, Therese; Jensen, Hanne B; Sundekilde, Ulrik K; Clausen, Morten R; Eggers, Nina; Larsen, Lotte B; Ray, Colin; Andersen, Henrik J; Bertram, Hanne C

2014-11-19

Proteolytic activity in milk may release bitter-tasting peptides and generate free amino terminals that react with carbohydrates, which initiate Maillard reaction. Ultrahigh temperature (UHT) heat treatment inactivates the majority of proteolytic enzymes in milk. In lactose-hydrolyzed milk a β-galactosidase preparation is applied to the milk after heat treatment, which has proteolytic side activities that may induce quality deterioration of long-term-stored milk. In the present study proteolysis, glycation, and volatile compound formation were investigated in conventional (100% lactose), filtered (60% lactose), and lactose-hydrolyzed (<1% lactose) UHT milk using reverse phase high-pressure liquid chromatography-mass spectrometry, proton nuclear magnetic resonance, and gas chromatography-mass spectrometry. Proteolysis was observed in all milk types. However, the degree of proteolysis was significantly higher in the lactose-hydrolyzed milk compared to the conventional and filtered milk. The proteins most prone to proteolysis were β-CN and αs1-CN, which were clearly hydrolyzed after approximately 90 days of storage in the lactose-hydrolyzed milk.

Dipeptidyl peptidase-4 (DPP-4) inhibitors are favourable to glucagon-like peptide-1 (GLP-1) agonists

DEFF Research Database (Denmark)

Madsbad, Sten

2012-01-01

Incretin-based therapies, which include the GLP-1 receptor agonists and DPP-4 inhibitors, use the antidiabetic properties of potentiating the GLP-1 receptor signalling via the regulation of insulin and glucagon secretion, inhibition of gastric emptying and suppression of appetite. Most physicians...... will start antidiabetic treatment with metformin, but adding a GLP-1 receptor agonist as the second drug seems to be optimal since more patients will reach an HbA1c below 7% than with a DPP-4 inhibitor or another oral antidiabetic agents and with minimal risk of hypoglycaemia. The GLP-1 receptor agonists...

Glucagon and plasma catecholamines during beta-receptor blockade in exercising man

DEFF Research Database (Denmark)

Galbo, H; Holst, Janett; Christensen, N J

1976-01-01

Seven men ran at 60% of individual maximal oxygen uptake to exhaustion during beta-adrenergic blockade with propranolol (P), during lipolytic blockade with nicotinic acid (N), or without drugs (C). The total work times (83 +/- 9 (P), 122 +/- 8 (N), 166 +/- 10 (C) min, mean and SE) differed signif...... determinants for the exercise-induced glucagon secretion in man. It is suggested that decreased glucose availability enhances the secretion of glucagon and epinephrine during prolonged exercise....

Glucagon dynamics during hypoglycaemia and food-re-challenge following treatment with vildagliptin in insulin-treated patients with type 2 diabetes.

Science.gov (United States)

Farngren, J; Persson, M; Schweizer, A; Foley, J E; Ahrén, B

2014-09-01

To determine the effects of dipeptidyl peptidase-4 (DPP-4) inhibition on glucagon dynamics in patients with insulin-treated type 2 diabetes (T2D). The study was a single-centre, double-blind, randomized, placebo controlled crossover study in patients with T2D, mean age 59 ± 6 (s.d.) years and mean haemoglobin A1c 7.7 ± 0.8%, treated with exogenous insulin with or without oral antihyperglycaemic agents. Patients received vildagliptin (50 mg BID) or placebo as add-on to insulin for 4 weeks in random order with a 4-week washout in-between. On day 28 of the respective treatment, patients were served a standard meal (500 kcal) followed by a hyperinsulinaemic hypoglycaemic clamp (target 2.5 mmol/l) and a subsequent food re-challenge (700 kcal). The completers population (n = 29) was analysed. Glucose levels were lower with vildagliptin than with placebo during the meal [areas under the curve (AUC) 1.23 ± 0.07 vs. 1.46 ± 0.05 mol/l min, P vildagliptin (AUC 1.98 ± 0.15 vs. 2.15 ± 0.17 nmol/l min, P = 0.016). In contrast, the glucagon counter-regulation to the insulin-induced hypoglycaemia was sustained by vildagliptin (6.05 ± 1.20 pmol/l during vildagliptin vs.6.94 ± 1.09 pmol/l during placebo, NS). During the food re-challenge after hypoglycaemia, glucagon levels were, again, significantly lower after vildagliptin (AUC 1.30 ± 0.11 vs. 1.52 ± 0.12 nmol/l min, P vildagliptin compared to placebo during meal, hypoglycaemia and food re-challenge. Vildagliptin action to block GLP-1 and GIP inactivation by DPP-4 improves glucagon dynamics during hypoglycaemia, hyperglycaemia and food re-challenge. © 2014 John Wiley & Sons Ltd.

Taking a position on intramembrane proteolysis.

Science.gov (United States)

Lemieux, M Joanne

2018-03-30

Decades of work have contributed to our in-depth mechanistic understanding of soluble proteases, but much less is known about the catalytic mechanism of intramembrane proteolysis due to inherent difficulties in both preparing and analyzing integral membrane enzymes and transmembrane substrates. New work from Naing et al. tackles this challenge by examining the catalytic parameters of an aspartyl intramembrane protease homologous to the enzyme that cleaves amyloid precursor protein, finding that both chemistry and register contribute to specificity in substrate cleavage. © 2018 Joanne Lemieux.

Oral glutamine increases circulating glucagon-like peptide 1, glucagon, and insulin concentrations in lean, obese, and type 2 diabetic subjects

DEFF Research Database (Denmark)

Greenfield, Jerry R; Farooqi, I Sadaf; Keogh, Julia M

2008-01-01

objective was to determine whether glutamine increases circulating GLP-1 and GIP concentrations in vivo and, if so, whether this is associated with an increase in plasma insulin. DESIGN: We recruited 8 healthy normal-weight volunteers (LEAN), 8 obese individuals with type 2 diabetes or impaired glucose...... plasma insulin concentrations. Glutamine stimulated glucagon secretion in all 3 study groups. CONCLUSION: Glutamine effectively increases circulating GLP-1, GIP, and insulin concentrations in vivo and may represent a novel therapeutic approach to stimulating insulin secretion in obesity and type 2......BACKGROUND: Incretin hormones, such as glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), play an important role in meal-related insulin secretion. We previously demonstrated that glutamine is a potent stimulus of GLP-1 secretion in vitro. OBJECTIVE: Our...

Effects of Preceding Ethanol Intake on Glucose Response to Low-Dose Glucagon in Individuals With Type 1 Diabetes

DEFF Research Database (Denmark)

Ranjan, Ajenthen; Nørgaard, Kirsten; Tetzschner, Rikke

2018-01-01

OBJECTIVE: This study investigated whether preceding ethanol intake impairs glucose response to low-dose glucagon in individuals with type 1 diabetes. RESEARCH DESIGN AND METHODS: This was a randomized, crossover, placebo-controlled study in 12 insulin pump-treated individuals (median...... ethanol compared with placebo. The second glucagon bolus had similar responses between visits, but PG remained 1.8 ± 0.7 mmol/L lower after ethanol compared with placebo. CONCLUSIONS: The ability of low-dose glucagon to treat mild hypoglycemia persisted with preceding ethanol intake, although it tended...... to be metabolized, and a subcutaneous (s.c.) insulin bolus was given to induce mild hypoglycemia. When plasma glucose (PG) was ≤3.9 mmol/L, 100 µg glucagon was given s.c., followed by another s.c. 100 µg glucagon 2 h later. Primary end point was incremental peak PG induced by the first glucagon bolus. RESULTS...

Glucagon-like peptide 1--a cardiologic dimension

DEFF Research Database (Denmark)

Treiman, Marek; Elvekjaer, Mikkel; Engstrøm, Thomas

2010-01-01

Recent experimental data suggest glucagon-like peptide 1 (GLP-1) and its analogs to have direct effects on the cardiovascular system, in addition to their classic glucoregulatory actions. These direct effects may be cardioprotective, contractility augmenting, and vasorelaxant. A few preliminary c...

Glucagon-like peptide-1 analogues: An overview

Directory of Open Access Journals (Sweden)

Vishal Gupta

2013-01-01

Full Text Available Abnormalities of the incretin axis have been implicated in the pathogenesis of type 2 diabetes mellitus. Glucagon-like peptide-1 (GLP-1 and gastroinhibitory intestinal peptide constitutes >90% of all the incretin function. Augmentation of GLP-1 results in improvement of beta cell health in a glucose-dependant manner (post-prandial hyperglycemia and suppression of glucagon (fasting hyperglycemia, amongst other beneficial pleiotropic effects. Native GLP-1 has a very short plasma half-life and novel methods have been developed to augment its half life, such that its anti-hyperglycemic effects can be exploited. They can be broadly classified as exendin-based therapies (exenatide, exenatide once weekly, DPP-4-resistant analogues (lixisenatide, albiglutide, and analogues of human GLP-1 (liraglutide, taspoglutide. Currently, commercially available analogues are exenatide, exenatide once weekly, and liraglutide. This review aims to provide an overview of most GLP-1 analogues.

Rapid purification of radiodinated glucagon with Sep-PakR reversed phase cartridges

International Nuclear Information System (INIS)

Borghi, V.C.; Nascimento, M.; Wajchenberg, B.L.

1989-01-01

A simple, rapid method is described for the purification of radioiodinated glucagon for use in radioimmunoassay. Samples of the radioiodinated hormone, before and after purification are analysed on polyacrylamide gel electrophoresis. The 125 I incorporation in these samples is also checked through thrichloroacetic acid precipitation. The usefulness of this labeled glucagon in radioimmunoassay is demonstrated by its biding to specific antibodies. (M.A.C.) [pt

Glucagon-like peptide-1 7-36 amide and peptide YY from the L-cell of the ileal mucosa are potent inhibitors of vagally induced gastric acid secretion in man

DEFF Research Database (Denmark)

Wettergren, A; Petersen, H; Orskov, C

1994-01-01

BACKGROUND: Glucagon-like peptide (GLP-1) 7-36 amide and peptide YY (PYY) from the L-cell of the ileal mucosa are potent inhibitors of gastric acid secretion in man. It is not clear, however, by which mechanism(s) they inhibit acid secretion. In dogs the inhibitory effect of PYY on acid secretion...

Circulating glucagon to ghrelin ratio as a determinant of insulin resistance in hyperthyroidism.

Science.gov (United States)

Ağbaht, Kemal; Erdogan, Murat Faik; Emral, Rifat; Baskal, Nilgun; Güllü, Sevim

2014-02-01

Due to stimulated overall metabolism, a state of nutritional inadequacy often ensues, during thyrotoxicosis. We aimed to investigate circulating levels of some major components of the system that regulates energy stores, glucose, and fat metabolism, during thyrotoxicosis compared to euthyroidism. Fasting serum ghrelin, leptin, adiponectin, insulin, glucagon, glucose, as well as body fat composition were analyzed during thyrotoxicosis in 40 hyperthyroid patients (50.5 ± 15.2 years old, 22 females, 31 with Graves disease, and 9 with toxic nodular goiter). The same measurements were repeated an average 3 months later, when all patients achieved euthyroidism. Compared to euthyroidism, in thyrotoxicosis, patients had lower ghrelin and fat mass; had comparable insulin, HOMA-IR, glucagon, and leptin levels; higher levels of circulating adiponectin. Fasting serum glucose tended to be higher during thyrotoxicosis. The unique correlation of HOMA-IR was with the-glucagon to ghrelin ratio-(r = 0.801, p hyperthyroidism. The fasting HOMA-IR tends to be higher, despite the decreased adiposity in hyperthyroidism. The-glucagon to ghrelin ratio-strongly correlates with fasting HOMA-IR in hyperthyroidism.

Evaluation of a sensitive and specific radioimmunoassay for pancreatic glucagon in human plasma and its clinical application

Energy Technology Data Exchange (ETDEWEB)

Borghi, V.C.; Wajchenberg, B.L.; Albuquerque, R.H. (Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil))

1984-01-16

A glucagon radioimmunoassay employing antiserum specific for pancreatic glucagon is described. Glucagon was radioiodinated by the chloramine T technique and purified on QAE-Sephadex A 25 to a specific activity of 225 ..mu..Ci/..mu..g. The standard curve allowed measurements from 12 to 500 pg/ml with sensitivity of 17.5 pg/ml, precision of 6.3-14.9% (CV, within-assay) and 5.6-10.7% (CV, between-assay). Recovery was between 82 and 112%. Fasting plasma glucagon levels in diabetics, obese subjects, acromegalics and patients with Cushing's syndrome were greater than in normals (22.0+-91 pg/ml: mean+-SD). Very low glucagon levels after oral glucose suppression (15.2+-3.1 pg/ml) in normals and greatly increased values after arginine in insulin-dependent diabetics (271.0+-132.3 pg/ml) could be determined.

Evaluation of a sensitive and specific radioimmunoassay for pancreatic glucagon in human plasma and its clinical application

International Nuclear Information System (INIS)

Borghi, V.C.; Wajchenberg, B.L.; Albuquerque, R.H.

1984-01-01

A glucagon radioimmunoassay employing antiserum specific for pancreatic glucagon is described. Glucagon was radioiodinated by the chloramine T technique and purified on QAE-Sephadex A 25 to a specific activity of 225 μCi/μg. The standard curve allowed measurements from 12 to 500 pg/ml with sensitivity of 17.5 pg/ml, precision of 6.3-14.9% (CV, within-assay) and 5.6-10.7% (CV, between-assay). Recovery was between 82 and 112%. Fasting plasma glucagon levels in diabetics, obese subjects, acromegalics and patients with Cushing's syndrome were greater than in normals (22.0+-91 pg/ml: mean+-SD). Very low glucagon levels after oral glucose suppression (15.2+-3.1 pg/ml) in normals and greatly increased values after arginine in insulin-dependent diabetics (271.0+-132.3 pg/ml) could be determined. (Auth.)

Stimulation of splanchnic glucose production during exercise in humans contains a glucagon-independent component

DEFF Research Database (Denmark)

Coker, R H; Simonsen, L; Bülow, J

2001-01-01

To determine the importance of basal glucagon to the stimulation of net splanchnic glucose output (NSGO) during exercise, seven healthy males performed cycle exercise during a pancreatic islet cell clamp. In one group (BG), glucagon was replaced at basal levels and insulin was adjusted to achieve...

Effect of glucagon-like peptide-1 on alpha- and beta-cell function in C-peptide-negative type 1 diabetic patients

DEFF Research Database (Denmark)

Kielgast, Urd; Asmar, Meena; Madsbad, Sten

2010-01-01

The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect.......The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect....

Effects of subcutaneous glucagon-like peptide 1 (GLP-1 [7-36 amide]) in patients with NIDDM

DEFF Research Database (Denmark)

Nauck, M A; Wollschläger, D; Werner, J

1996-01-01

with the indicator-dilution method and phenol red. Repeated measures ANOVA was used for statistical analysis. GLP-1 injection led to a short-lived increment in GLP-1 concentrations (peak at 30-60 min, then return to basal levels after 90-120 min). Each GLP-1 injection stimulated insulin (insulin, C-peptide, p ....0001, respectively) and inhibited glucagon secretion (p ... emptying for 30-45 min (p statistically different from placebo) followed by emptying at a normal rate. As a consequence, integrated incremental glucose responses were reduced by 40% (p = 0.051). In conclusion, subcutaneous GLP-1 [7-36 amide] has similar effects in NIDDM patients as an intravenous...

Modelling of glucose-insulin-glucagon pharmacodynamics in man

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Møller, Jan Kloppenborg; Haidar, A.

The purpose is to build a simulation model of the glucoregulatory system in man. We estimate individual human parameters of a physiological glucose-insulin-glucagon model. We report posterior probability distributions and correlations of model parameters....

The effect of different packaging materials on proteolysis, sensory ...

African Journals Online (AJOL)

In this study, tulum cheese was manufactured using raw ewe's milk and was ripened in goat's skin and plastic bags. The effect of ripening materials (skin bag or plastic) on proteolysis was investigated during 120 days of ripening. In addition, sensory scores of the cheeses were assessed at the 90th and 120th days.

Localization of glucagon and insulin cells and its variation with respect to physiological events in Eutropis carinata

Directory of Open Access Journals (Sweden)

Vidya. R. Chandavar

2011-06-01

Full Text Available The aim of the present investigation was to localize glucagon and insulin immunoreactive (IR cells of pancreas during annual seasonal cycle of reproduction and to find out whether they had any effect on the regulation of plasma glucose level in the skink Eutropis carinata. Immunolocalized pancreatic cells revealed significantly different mean numbers in different periods of reproduction. The numbers of glucagon-IR and insulin-IR cells were highest in recrudescent period which was corresponded with low plasma glucose level. Unlike other lizards the arrangement of insulin cells in the central core and glucagon cells at the periphery was absent instead glucagon-IR and insulin-IR cells were paracrine in arrangement. Among the two immunoreactive cells glucagon-IR cells were predominant. Morphological differences between two cell types were observed by electron microscopy after staining with uranyl acetate and lead citrate. Plasma glucose showed cyclic change being highest during reproductive period.

The role of insulin and glucagon in experimental obstructive jaundice.

Science.gov (United States)

Chen, J S; Ker, C G; Sheen, P C

1999-01-01

The oxidative phosphorylation of liver mitochondria is regulated by the amount of portal insulin available to the hepatocytes. Thus, hepatic energy is mediated by the values of blood sugar and insulin. Insulin and glucagon are the main fuel homeostats in the liver. This study was performed to investigate the concept of energy mediated by glucose, during the process of obstructive jaundice and its recovery. Experimental Wistar rats were studied, with bile duct tied for 4, 7 and 14 days respectively. The serum concentration and relative tissue concentration of insulin and glucagon were measured. And the common bile duct was tied for 4, 7 and 14 days, then relieved by time sequences for 4, 7 and 14 days. Serum concentration and relative tissue concentration of insulin and glucagon were also measured. When the common bile duct was tied for 4, 7, and 14 days respectively, the serum concentration and relative tissue concentration of insulin declined (p jaundice, more fuel is demanded to make up for the energy deficiency. In spite of surgical or non-surgical relief of obstructive jaundice, the energy reserve is still not sufficiently recovered. The recovery of the hepatic energy reserve takes longer than we expected.

The lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes.

Science.gov (United States)

Bergantin, Leandro Bueno; Figueiredo, Leonardo Bruno; Godinho, Rosely Oliveira

2011-12-01

The molecular regulation of skeletal muscle proteolysis and the pharmacological screening of anticatabolic drugs have been addressed by measuring tyrosine release from prepubertal rat skeletal muscles, which are thin enough to allow adequate in vitro diffusion of oxygen and substrates. However, the use of muscle at accelerated prepubertal growth has limited the analysis of adult muscle proteolysis or that associated with aging and neurodegenerative diseases. Here we established the adult rat lumbrical muscle (4/hindpaw; 8/rat) as a new in situ experimental model for dynamic measurement of skeletal muscle proteolysis. By incubating lumbrical muscles attached to their individual metatarsal bones in Tyrode solution, we showed that the muscle proteolysis rate of adult and aged rats (3-4 to 24 mo old) is 45-25% of that in prepubertal animals (1 mo old), which makes questionable the usual extrapolation of proteolysis from prepubertal to adult/senile muscles. While acute mechanical injury or 1- to 7-day denervation increased tyrosine release from adult lumbrical muscle by up to 60%, it was reduced by 20-28% after 2-h incubation with β-adrenoceptor agonists, forskolin or phosphodiesterase inhibitor IBMX. Using inhibitors of 26S-proteasome (MG132), lysosome (methylamine), or calpain (E64/leupeptin) systems, we showed that ubiquitin-proteasome is accountable for 40-50% of total lumbrical proteolysis of adult, middle-aged, and aged rats. In conclusion, the lumbrical model allows the analysis of muscle proteolysis rate from prepubertal to senile rats. By permitting eight simultaneous matched measurements per rat, the new model improves similar protocols performed in paired extensor digitorum longus (EDL) muscles from prepubertal rats, optimizing the pharmacological screening of drugs for anticatabolic purposes.

Gastric inhibitory polypeptide (GIP) dose-dependently stimulates glucagon secretion in healthy human subjects at euglycaemia

DEFF Research Database (Denmark)

Meier, J J; Gallwitz, B; Siepmann, N

2003-01-01

AIMS/HYPOTHESIS: In the isolated perfused pancreas, gastric inhibitory polypeptide (GIP) has been shown to enhance glucagon secretion at basal glucose concentrations, but in healthy humans no glucagonotropic effect of GIP has yet been reported. Therefore, we studied the effect of GIP on glucagon ...

The effect of different protein hydrolysate/carbohydrate mixtures on postprandial glucagon and insulin responses in healthy subjects.

Science.gov (United States)

Claessens, M; Calame, W; Siemensma, A D; van Baak, M A; Saris, W H M

2009-01-01

To study the effect of four protein hydrolysates from vegetable (pea, gluten, rice and soy) and two protein hydrolysates from animal origin (whey and egg) on glucagon and insulin responses. Eight healthy normal-weight male subjects participated in this study. The study employed a repeated-measures design with Latin square randomization and single-blind trials. Protein hydrolysates used in this study (pea, rice, soy, gluten, whey and egg protein hydrolysate) consisted of 0.2 g hydrolysate per kg body weight (bw) and 0.2 g maltodextrin per kg bw and were compared to maltodextrin alone. Postprandial plasma glucose, glucagon, insulin and amino acids were determined over 2 h. All protein hydrolysates induced an enhanced insulin secretion compared to maltodextrin alone and a correspondingly low plasma glucose response. A significant difference was observed in area under the curve (AUC) for plasma glucagon between protein hydrolysates and the maltodextrin control drink (Pprotein hydrolysate induced the lowest glucagon response. High amino-acid-induced glucagon response does not necessarily go together with low insulin response. Protein hydrolysate source affects AUC for glucagon more profoundly than for insulin, although the protein load used in this study seemed to be at lower level for significant physiological effects.

Neutral endopeptidase 24.11 is important for the degradation of both endogenous and exogenous glucagon in anesthetized pigs

DEFF Research Database (Denmark)

Trebbien, Ramona; Klarskov, Letty; Olesen, Mette

2004-01-01

, a selective NEP inhibitor, on plasma levels of endogenous and exogenous glucagon was examined in anesthetized pigs. Candoxatril increased endogenous glucagon concentrations, from 6.3 +/- 2.5 to 20.7 +/- 6.3 pmol/l [COOH-terminal (C)-RIA, P ...-RIA). This study provides evidence that NEP 24.11 is an important mediator of the degradation of both endogenous and exogenous glucagon in vivo....

Effects of natural plant tenderizers on proteolysis and texture of dry ...

African Journals Online (AJOL)

, and overall acceptability. From these results, it is shown that those enzymes as a raw plant juices could be used as tenderizers in dry sausage production. Keywords: Dry sausages, wild boar meat, plant enzymes, proteolysis, texture, sensory ...

Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production

Directory of Open Access Journals (Sweden)

Nicolai J. Wewer Albrechtsen

2017-11-01

Full Text Available Glucagon is secreted from pancreatic α cells, and hypersecretion (hyperglucagonemia contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among which proglucagon 1-61 (PG 1-61 appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β cells demonstrated that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in vivo. We conclude that glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion.

The cachectic mediator proteolysis inducing factor activates NF-kappaB and STAT3 in human Kupffer cells and monocytes

NARCIS (Netherlands)

Watchorn, T.M.; Dowidar, N.; Dejong, C.H.; Waddell, I.D.; Garden, O.J.; Ross, J.A.

2005-01-01

A novel proteoglycan, proteolysis inducing factor (PIF), is capable of inducing muscle proteolysis during the process of cancer cachexia, and of inducing an acute phase response in human hepatocytes. We investigated whether PIF is able to activate pro-inflammatory pathways in human Kupffer cells,

Glucagon effects on the membrane potential and calcium uptake rate of rat liver mitochondria

International Nuclear Information System (INIS)

Wingrove, D.E.; Amatruda, J.M.; Gunter, T.E.

1984-01-01

It has been widely reported that the in vivo administration of glucagon to rats results in the stimulation of calcium influx in subsequently isolated liver mitochondria. The mechanism of this effect is investigated through simultaneous measurements of calcium uptake rate and mitochondrial membrane potential. This allows the measurement of the calcium uniporter conductance independent of hormonal effects on electron transport or respiration. Two experimental approaches are used. The first involves measuring the uptake of 40-50 nmol of Ca 2+ /mg of mitochondrial protein with the calcium dye antipyrylazo III; the second uses 45 Ca 2+ to follow uptake in the presence of 0.5 to 1.5 μM free calcium, buffered with HEDTA. In both cases a tetraphenyl phosphonium electrode is used to follow membrane potential, and membrane potential is varied using either malonate or butylmalonate in the presence of rotenone. The relative merits of these two approaches are discussed. The conductance of the calcium uniporter is found not to be stimulated by glucagon pretreatment. Also, the relative glucagon stimulation of both calcium influx and membrane potential is found to increase with increasing malonate concentration. These results imply that there is no direct stimulation of calcium uptake into liver mitochondria following glucagon treatment. The results are consistent with a glucagon stimulation of substrate transport, substrate oxidation, or a stimulation of electron transport resulting in an increased membrane potential and secondary stimulation of calcium uptake

Implications of the Maillard reaction on bovine alpha-lactalbumin and its proteolysis during in vitro infant digestion.

Science.gov (United States)

Joubran, Yousef; Moscovici, Alice; Portmann, Reto; Lesmes, Uri

2017-06-21

This study investigated the functionality and digestibility of Maillard reaction products (MRPs) of alpha-lactalbumin (α-la), a major whey protein and component of infant formulas. The impact of different carbohydrates (glucose, galactose or galacto-oligosaccharides (GOS)) and heating duration was studied. SDS-PAGE, UV and color measurements monitored reaction extent, which varied between carbohydrates whereby galactose reacted more readily than glucose. Surface hydrophobicity and antioxidant capacity were found to be significantly (p Maillard conjugation, with GOS-based MRPs elevating antioxidant capacity ∼50-fold compared to α-la. In addition, the digestive proteolysis of MRPs was evaluated using an infant in vitro gastro-duodenal model. SDS-PAGE analyses of digesta revealed Maillard conjugation generally increased α-la's susceptibility to proteolysis. Interestingly, GOS-based MRPs presented an optimization challenge, since heating for 12 h delayed proteolysis, while extended heating resulted in the highest susceptibility to proteolysis. Proteomic analyses further demonstrated the differences in enzymatic cleavage patterns and helped identify bioactive peptides rendered bioaccessible during the digestion of α-la or its MRPs. Bioinformatic mining of the proteomic data using PeptideRanker also gave rise to two potentially novel bioactive peptides, FQINNKIW and GINYWLAHKALCS. Finally, antioxidant capacity of luminal contents, measured by DPPH, revealed Maillard conjugation increased the antioxidant capacity of both gastric and duodenal digesta. Overall, this work draws a link between the Maillard reaction, digestive proteolysis and the bioaccessibility of bioactive peptides and antioxidant species in the infant alimentary canal. This could help rationally process infant formulas towards improved nutritional and extra-nutritional benefits.

Early changes in plasma glucagon and growth hormone response to oral glucose in experimental hyperthyroidism.

Science.gov (United States)

Tosi, F; Moghetti, P; Castello, R; Negri, C; Bonora, E; Muggeo, M

1996-08-01

The mechanisms underlying deterioration of glucose tolerance associated with hyperthyroidism are not completely understood. Increases in glucagon and growth hormone (GH) secretion have been previously found in hyperthyroid subjects, and could play a crucial role in this phenomenon. However, studies have not yet established the time sequence of changes in plasma glucose on the one hand and glucagon and GH on the other. To assess the early effects of thyroid hormone excess on glucose tolerance and plasma concentrations of the main glucoregulatory hormones, 12 nondiabetic euthyroid subjects underwent an oral glucose tolerance test (OGTT) before and after triiodothyronine ([T3] 120 micrograms/d) was administered for 10 days. Plasma levels of glucose, insulin, glucagon, and GH were determined at fasting and after the glucose load. T3 administration caused a marked increase in serum T3 (8.8 +/- 0.6 v 2.0 +/- 0.1 nmol/L), with clinical and biochemical signs of thyrotoxicosis. During the treatment, plasma glucose significantly increased both at fasting and after the glucose load (basal, 5.3 +/- 0.1 v 4.9 +/- 0.2 mmol/L, P hormone excess rapidly impairs glucose tolerance. Altered secretion of GH is an early event in thyrotoxicosis accompanying the onset of hyperglycemia, whereas plasma glucagon is appropriately suppressed by the increased plasma glucose levels. Thus, GH but not glucagon may contribute to the early hyperglycemic effect of thyrotoxicosis.

Inhibition of post-traumatic septic proteolysis and ureagenesis and stimulation of hepatic acute-phase protein production by branched-chain amino acid TPN.

Science.gov (United States)

Chiarla, C; Siegel, J H; Kidd, S; Coleman, B; Mora, R; Tacchino, R; Placko, R; Gum, M; Wiles, C E; Belzberg, H

1988-08-01

Previous studies have shown that severe sepsis after major trauma results in the reprioritization of release of hepatic acute-phase proteins (APP). They suggest competition for leucine for nutritional utilization may be responsible. To test this hypothesis, a branched-chain enriched (46.6%) amino acid mixture (BCAA) was administered on a prospective randomized basis with standard TPN therapy to 16 septic post-trauma patients. After sepsis was diagnosed, a randomized therapy (control-TPN or BCAA-TPN) was given for 12 days, or until death occurred. Total calories and amino acid nitrogen (N) administered were not different in the two groups (t-test) and q 8 h (347 study periods) amino acid clearances, urinary urea nitrogen excretion, muscle proteolysis from 3-methyl-histidine (3-MH) excretion, and standard indices of sepsis severity and hepatic function were measured, as well as platelets (PLAT), leucocytes (WBC), albumin (ALB), and six acute-phase proteins: C-reactive protein (CRP), alpha-1-antitrypsin (A1TRIP), fibrinogen (FIBRIN), alpha-2-macroglobulin (AMACRO), ceruloplasmin (CERUL), and transferrin (TRANS). Using Scheffé analysis of all contrasts the data showed: BCAA resulted in a fall in 24-hour urea N excretion (24.0 to 20.0 gm/24 hr) and in proteolysis (138 to 126 gm/24 hr) (p less than 0.0001). Prestudy CRP levels were all elevated, but compared to control where APP reprioritization occurred, over the initial 10 days of therapy BCAA patients had a more rapid fall in CRP with a more rapid rise in FIBRIN, TRANS, CERUL, ALBUMIN, AMACRO, and A1TRIP (all p less than 0.0001) relative to CRP. Also, the sepsis-reduced clearances of glutamine and glutamate, alanine, and proline were increased (p less than 0.0001) during BCAA even though urea nitrogen production was reduced (p less than 0.0001). The increase in leucine clearance with BCAA-enriched TPN was positively correlated (r2 = 0.601; p less than 0.0001) with the increase in the sum of all APP and ALB and was

Dynamics of glucagon secretion in mice and rats revealed using a validated sandwich ELISA for small sample volumes

DEFF Research Database (Denmark)

Albrechtsen, Nicolai Jacob Wewer; Kuhre, Rune Ehrenreich; Windeløv, Johanne Agerlin

2016-01-01

Glucagon is a metabolically important hormone, but many aspects of its physiology remain obscure, because glucagon secretion is difficult to measure in mice and rats due to methodological inadequacies. Here, we introduce and validate a low-volume, enzyme-linked immunosorbent glucagon assay...... according to current analytical guidelines, including tests of sensitivity, specificity, and accuracy, and compare it, using the Bland-Altman algorithm and size-exclusion chromatography, with three other widely cited assays. After demonstrating adequate performance of the assay, we measured glucagon...... and returning to basal levels at 6 min (mice) and 12 min (rats). d-Mannitol (osmotic control) was without effect. Ketamine/xylazine anesthesia in mice strongly attenuated (P assay. In conclusion, dynamic analysis...

Locked and proteolysis-based transcription activator-like effector (TALE) regulation.

Science.gov (United States)

Lonzarić, Jan; Lebar, Tina; Majerle, Andreja; Manček-Keber, Mateja; Jerala, Roman

2016-02-18

Development of orthogonal, designable and adjustable transcriptional regulators is an important goal of synthetic biology. Their activity has been typically modulated through stimulus-induced oligomerization or interaction between the DNA-binding and activation/repression domain. We exploited a feature of the designable Transcription activator-like effector (TALE) DNA-binding domain that it winds around the DNA which allows to topologically prevent it from binding by intramolecular cyclization. This new approach was investigated through noncovalent ligand-induced cyclization or through a covalent split intein cyclization strategy, where the topological inhibition of DNA binding by cyclization and its restoration by a proteolytic release of the topologic constraint was expected. We show that locked TALEs indeed have diminished DNA binding and regain full transcriptional activity by stimulation with the rapamycin ligand or site-specific proteolysis of the peptide linker, with much higher level of activation than rapamycin-induced heterodimerization. Additionally, we demonstrated reversibility, activation of genomic targets and implemented logic gates based on combinations of protein cyclization, proteolytic cleavage and ligand-induced dimerization, where the strongest fold induction was achieved by the proteolytic cleavage of a repression domain from a linear TALE. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Estrogen receptor of primary breast cancers: evidence for intracellular proteolysis

International Nuclear Information System (INIS)

Maaroufi, Younes; Lacroix, Marc; Lespagnard, Laurence; Journé, Fabrice; Larsimont, Denis; Leclercq, Guy

2000-01-01

Iodinated oestradiol-labeled oestrogen receptor (ER) isoforms devoid of amino-terminal ABC domains represent about two-thirds of the whole receptor population detected in cytosol samples from human breast cancers. This high frequency could not be ascribed to the expression of truncated mRNAs, or to the proteolysis of the native ER peptide at the time of homogenization or assay, suggesting an intracellular proteolysis. Free amino-terminal and ligand-binding domains maintained together within oligomeric structure(s); increase of ionic strength separated them. The amino-terminal region was consistently detected in the cell nucleus by specific immunohistochemistry leading to the concept of a potential intranuclear association between ER cleavage products and/or other regulatory proteins. We previously reported that about two-thirds of [ 125 I]oestradiol-labelled cytosolic ERs from breast cancer samples eluted as low-molecular-weight isoforms (≤ 37 kDa, size-exclusion fast pressure liquid chromatography [FPLC]). These isoforms failed to adsorb strongly to hydroxylapatite at high ionic strength, a property that was ascribed to receptors devoid of amino-terminal ABC domains. In view of recent data concerning intracellular proteolysis of several transcriptional regulators, the possibility of such behaviour for ER was assessed. The clinical significance of ER measurement in breast cancer cytosols is well established; approximately 50% of ER-positive cases respond to endocrine therapy. Whether such a poor correlation is related to a high proportion of cleaved ER is a question of prime importance. Failure of routine ER assays to discriminate between full-length and cleaved receptors led us to develop an oestradiol-binding assay based on hydroxylapatite adsorption. The aims of the present study were to demonstrate that hydroxylapatite adsorption assay easily identifies cleaved cytosolic ER forms and to assess the origin of such ER forms. Breast cancer cytosols classified as

Plant senescence and proteolysis: two processes with one destiny.

Science.gov (United States)

Diaz-Mendoza, Mercedes; Velasco-Arroyo, Blanca; Santamaria, M Estrella; González-Melendi, Pablo; Martinez, Manuel; Diaz, Isabel

2016-01-01

Senescence-associated proteolysis in plants is a complex and controlled process, essential for mobilization of nutrients from old or stressed tissues, mainly leaves, to growing or sink organs. Protein breakdown in senescing leaves involves many plastidial and nuclear proteases, regulators, different subcellular locations and dynamic protein traffic to ensure the complete transformation of proteins of high molecular weight into transportable and useful hydrolysed products. Protease activities are strictly regulated by specific inhibitors and through the activation of zymogens to develop their proteolytic activity at the right place and at the proper time. All these events associated with senescence have deep effects on the relocation of nutrients and as a consequence, on grain quality and crop yield. Thus, it can be considered that nutrient recycling is the common destiny of two processes, plant senescence and, proteolysis. This review article covers the most recent findings about leaf senescence features mediated by abiotic and biotic stresses as well as the participants and steps required in this physiological process, paying special attention to C1A cysteine proteases, their specific inhibitors, known as cystatins, and their potential targets, particularly the chloroplastic proteins as source for nitrogen recycling.

Gcg-XTEN: an improved glucagon capable of preventing hypoglycemia without increasing baseline blood glucose.

Directory of Open Access Journals (Sweden)

Nathan C Geething

2010-04-01

Full Text Available While the majority of current diabetes treatments focus on reducing blood glucose levels, hypoglycemia represents a significant risk associated with insulin treatment. Glucagon plays a major regulatory role in controlling hypoglycemia in vivo, but its short half-life and hyperglycemic effects prevent its therapeutic use for non-acute applications. The goal of this study was to identify a modified form of glucagon suitable for prophylactic treatment of hypoglycemia without increasing baseline blood glucose levels.Through application of the XTEN technology, we report the construction of a glucagon fusion protein with an extended exposure profile (Gcg-XTEN. The in vivo half-life of the construct was tuned to support nightly dosing through design and testing in cynomolgus monkeys. Efficacy of the construct was assessed in beagle dogs using an insulin challenge to induce hypoglycemia. Dose ranging of Gcg-XTEN in fasted beagle dogs demonstrated that the compound was biologically active with a pharmacodynamic profile consistent with the designed half-life. Prophylactic administration of 0.6 nmol/kg Gcg-XTEN to dogs conferred resistance to a hypoglycemic challenge at 6 hours post-dose without affecting baseline blood glucose levels. Consistent with the designed pharmacokinetic profile, hypoglycemia resistance was not observed at 12 hours post-dose. Importantly, the solubility and stability of the glucagon peptide were also significantly improved by fusion to XTEN.The data show that Gcg-XTEN is effective in preventing hypoglycemia without the associated hyperglycemia expected for unmodified glucagon. While the plasma clearance of this Gcg-XTEN has been optimized for overnight dosing, specifically for the treatment of nocturnal hypoglycemia, constructs with significantly longer exposure profiles are feasible. Such constructs may have multiple applications such as allowing for more aggressive insulin treatment regimens, treating hypoglycemia due to insulin

Visualization of glucagon secretion from pancreatic α cells by bioluminescence video microscopy: Identification of secretion sites in the intercellular contact regions

International Nuclear Information System (INIS)

Yokawa, Satoru; Suzuki, Takahiro; Inouye, Satoshi; Inoh, Yoshikazu; Suzuki, Ryo; Kanamori, Takao; Furuno, Tadahide; Hirashima, Naohide

2017-01-01

We have firstly visualized glucagon secretion using a method of video-rate bioluminescence imaging. The fusion protein of proglucagon and Gaussia luciferase (PGCG-GLase) was used as a reporter to detect glucagon secretion and was efficiently expressed in mouse pancreatic α cells (αTC1.6) using a preferred human codon-optimized gene. In the culture medium of the cells expressing PGCG-GLase, luminescence activity determined with a luminometer was increased with low glucose stimulation and KCl-induced depolarization, as observed for glucagon secretion. From immunochemical analyses, PGCG-GLase stably expressed in clonal αTC1.6 cells was correctly processed and released by secretory granules. Luminescence signals of the secreted PGCG-GLase from the stable cells were visualized by video-rate bioluminescence microscopy. The video images showed an increase in glucagon secretion from clustered cells in response to stimulation by KCl. The secretory events were observed frequently at the intercellular contact regions. Thus, the localization and frequency of glucagon secretion might be regulated by cell-cell adhesion. - Highlights: • The fused protein of proglucagon to Gaussia luciferase was used as a reporter. • The fusion protein was highly expressed using a preferred human-codon optimized gene. • Glucagon secretion stimulated by depolarization was determined by luminescence. • Glucagon secretion in α cells was visualized by bioluminescence imaging. • Glucagon secretion sites were localized in the intercellular contact regions.

Neonatal intramuscular injection of plasmid encoding glucagon-like

Indian Academy of Sciences (India)

Glucagon-like peptide-1 (GLP-1) has been implicated in the regulation of neuroendocrine and behavioural responses, but it is yet to be determined whether and how neonatal GLP-1 overexpression may modify hippocampal GR expression and thus programme adolescent behaviour in rats. Two-dayold pups were injected ...

A primary study on texture modification and proteolysis of mao-tofu ...

African Journals Online (AJOL)

Proteolysis occurred during fermentation was evaluated by SDS-PAGE and chemical analysis. Results from Texture Profile Analysis showed that adhesiveness of mao-tofu had an increase trend while hardness, cohesiveness and springiness had a decrease trend as fermentation progressed. SEM analysis showed that the ...

Significance of glucagon for insulin secretion and hepatic glycogenolysis during exercise in rats

DEFF Research Database (Denmark)

Richter, Erik; Galbo, H; Holst, J J

1981-01-01

The significance of glucagon and of the sympatho-adrenal system for insulin secretion and hepatic glycogen depletion during exercise was studied. Male rats were either adrenodemedullated and chemically sympathectomized with 6-hydroxydopamine (SX) or sham-treated (C). During light ether anesthesia......, cardiac blood for glucose analysis and a biopsy of the liver were obtained, and either antigen-stripped glucagon antibodies (A) or control gamma globulins (N) in saline were injected through the cardiac cannula. Subsequently, the rats swam in tepid water (33-34 degree C) for 100 minutes with a tail weight...... attached (2% of body weight). Then cardiac blood was drawn for analysis of glucose, insulin and glucagon, and a sample of the liver was collected. In both CA and CN rats, the blood glucose concentration tended to increase (p less than 0.1) during exercise, whereas hepatic glycogen depletion and the plasma...

The contribution of glucagon in an Artificial Pancreas for people with type 1 diabetes

DEFF Research Database (Denmark)

Bátora, Vladimír; Tárník, Marián; Murgas, Ján

2015-01-01

insulin to treat hyperglycemia as well as glucagon to ensure fast recovery from hypoglycemic episodes. Two separate model predictive controllers (MPC) based on patient-specific models handle insulin and glucagon infusion. In addition, the control algorithm consists of a Kalman filter and a meal time...... and a bolus overestimated by 60%. During normal operation both strategies provide similar results. The contribution of glucagon becomes evident after administration of the overestimated insulin bolus. In a 10h period following an overbolused meal, the bihormonal strategy reduces time spent in hypoglycemia...... insulin bolus calculator. The feedback is obtained from a continuous glucose monitor (CGM). We implement a bihormonal simulation model with time-varying parameters available for 3 subjects to compare the strategies. We consider a protocol with 3 events - a correct mealtime insulin bolus, a missed bolus...

Collagen fibril architecture, domain organization, and triple-helical conformation govern its proteolysis.

Science.gov (United States)

Perumal, Shiamalee; Antipova, Olga; Orgel, Joseph P R O

2008-02-26

We describe the molecular structure of the collagen fibril and how it affects collagen proteolysis or "collagenolysis." The fibril-forming collagens are major components of all mammalian connective tissues, providing the structural and organizational framework for skin, blood vessels, bone, tendon, and other tissues. The triple helix of the collagen molecule is resistant to most proteinases, and the matrix metalloproteinases that do proteolyze collagen are affected by the architecture of collagen fibrils, which are notably more resistant to collagenolysis than lone collagen monomers. Until now, there has been no molecular explanation for this. Full or limited proteolysis of the collagen fibril is known to be a key process in normal growth, development, repair, and cell differentiation, and in cancerous tumor progression and heart disease. Peptide fragments generated by collagenolysis, and the conformation of exposed sites on the fibril as a result of limited proteolysis, regulate these processes and that of cellular attachment, but it is not known how or why. Using computational and molecular visualization methods, we found that the arrangement of collagen monomers in the fibril (its architecture) protects areas vulnerable to collagenolysis and strictly governs the process. This in turn affects the accessibility of a cell interaction site located near the cleavage region. Our observations suggest that the C-terminal telopeptide must be proteolyzed before collagenase can gain access to the cleavage site. Collagenase then binds to the substrate's "interaction domain," which facilitates the triple-helix unwinding/dissociation function of the enzyme before collagenolysis.

Exaggerated secretion of glucagon-like peptide-1 (GLP-1) could cause reactive hypoglycaemia

DEFF Research Database (Denmark)

Toft-Nielsen, M; Madsbad, Sten; Holst, Jens Juul

1998-01-01

The plasma concentrations of the insulinotropic incretin hormone, glucagon-like peptide-1 (GLP-1) are abnormally high after oral glucose in partially gastrectomised subjects with reactive hypoglycaemia, suggesting a causal relationship. Because of the glucose-dependency of its effects, it is impo......The plasma concentrations of the insulinotropic incretin hormone, glucagon-like peptide-1 (GLP-1) are abnormally high after oral glucose in partially gastrectomised subjects with reactive hypoglycaemia, suggesting a causal relationship. Because of the glucose-dependency of its effects...

Peptides Displayed as High Density Brush Polymers Resist Proteolysis and Retain Bioactivity

Science.gov (United States)

2015-01-01

We describe a strategy for rendering peptides resistant to proteolysis by formulating them as high-density brush polymers. The utility of this approach is demonstrated by polymerizing well-established cell-penetrating peptides (CPPs) and showing that the resulting polymers are not only resistant to proteolysis but also maintain their ability to enter cells. The scope of this design concept is explored by studying the proteolytic resistance of brush polymers composed of peptides that are substrates for either thrombin or a metalloprotease. Finally, we demonstrate that the proteolytic susceptibility of peptide brush polymers can be tuned by adjusting the density of the polymer brush and offer in silico models to rationalize this finding. We contend that this strategy offers a plausible method of preparing peptides for in vivo use, where rapid digestion by proteases has traditionally restricted their utility. PMID:25314576

Validation of a Simulation Model Describing the Glucose-Insulin-Glucagon Pharmacodynamics in Patients with Type 1 Diabetes

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Ranjan, Ajenthen; Møller, Jan Kloppenborg

Currently, no consensus exists on a model describing endogenous glucose production (EGP) as a function of glucagon concentrations. Reliable simulations to determine the glucagon dose preventing or treating hypoglycemia or to tune a dual-hormone artificial pancreas control algorithm need a validat...

The effect of glucagon infusion on kidney function in short-term insulin-dependent juvenile diabetics

DEFF Research Database (Denmark)

Parving, H H; Christiansen, J S; Noer, I

1980-01-01

Kidney function was studied in nine, metabolically well controlled, short-term insulin-dependent male diabetics before and during glucagon infusion of 4 to 5 and 8 to 10 ng/kg/min. Glomerular filtration rate, effective renal plasma flow (steady-state infusion technique, with urinary collections......, using 125I-iothalamate and 131I-iodohippurate), and urinary albumin and beta 2-microglobulin excretion rates were measured. The mean plasma glucagon concentration increased during infusion from 254 +/- 19 pg/ml to 440 +/- 31 pg/ml (low dose) and 730 +/- 52 pg/ml (high dose). Glomerular filtration rate...... increased in all subjects from 133 +/- 5 before the glucagon infusion to 141 +/- 4 with the low dose, and 148 +/- 7 ml/min/1.73 m2 with the high dose (p

Label-free detection of insulin and glucagon within human islets of Langerhans using Raman spectroscopy.

Directory of Open Access Journals (Sweden)

Janneke Hilderink

Full Text Available Intrahepatic transplantation of donor islets of Langerhans is a promising therapy for patients with type 1 diabetes. It is of critical importance to accurately monitor islet quality before transplantation, which is currently done by standard histological methods that are performed off-line and require extensive sample preparation. As an alternative, we propose Raman spectroscopy which is a non-destructive and label-free technique that allows continuous real-time monitoring of the tissue to study biological changes as they occur. By performing Raman spectroscopic measurements on purified insulin and glucagon, we showed that the 520 cm(-1 band assigned to disulfide bridges in insulin, and the 1552 cm(-1 band assigned to tryptophan in glucagon are mutually exclusive and could therefore be used as indirect markers for the label-free distinction between both hormones. High-resolution hyperspectral Raman imaging for these bands showed the distribution of disulfide bridges and tryptophan at sub-micrometer scale, which correlated with the location of insulin and glucagon as revealed by conventional immunohistochemistry. As a measure for this correlation, quantitative analysis was performed comparing the Raman images with the fluorescence images, resulting in Dice coefficients (ranging between 0 and 1 of 0.36 for insulin and 0.19 for glucagon. Although the use of separate microscope systems with different spatial resolution and the use of indirect Raman markers cause some image mismatch, our findings indicate that Raman bands for disulfide bridges and tryptophan can be used as distinctive markers for the label-free detection of insulin and glucagon in human islets of Langerhans.

Low-Carbohydrate Diet Impairs the Effect of Glucagon in the Treatment of Insulin-Induced Mild Hypoglycemia

DEFF Research Database (Denmark)

Ranjan, Ajenthen; Schmidt, Signe; Damm-Frydenberg, Camilla

2017-01-01

OBJECTIVE: This study compared the ability of glucagon to restore plasma glucose (PG) after mild hypoglycemia in patients with type 1 diabetes on an isocaloric high-carbohydrate diet (HCD) versus a low-carbohydrate diet (LCD). RESEARCH DESIGN AND METHODS: Ten patients with insulin pump-treated type...... 1 diabetes randomly completed 1 week of the HCD (≥250 g/day) and 1 week of the LCD (≤50 g/day). After each week, mild hypoglycemia was induced by a subcutaneous insulin bolus in the fasting state. When PG reached 3.9 mmol/L, 100 µg glucagon was given subcutaneously, followed by 500 µg glucagon 2 h...... later. RESULTS: Compared with the HCD, the LCD resulted in lower incremental rises in PG after the first (mean ± SEM: 1.3 ± 0.3 vs. 2.7 ± 0.4 mmol/L, P = 0.002) and second glucagon bolus (4.1 ± 0.2 vs. 5.6 ± 0.5 mmol/L, P = 0.002). No differences were observed between the diets regarding concentrations...

Angiopoietin-like protein 4 is an exercise-induced hepatokine in humans, regulated by glucagon and cAMP

Directory of Open Access Journals (Sweden)

Bodil Ingerslev

2017-10-01

Conclusions: The data suggest that exercise-induced ANGPTL4 is secreted from the liver and driven by a glucagon-cAMP-PKA pathway in humans. These findings link the liver, insulin/glucagon, and lipid metabolism together, which could implicate a role of ANGPTL4 in metabolic diseases.

Myocardial overexpression of TIMP3 after myocardial infarction exerts beneficial effects by promoting angiogenesis and suppressing early proteolysis.

Science.gov (United States)

Takawale, Abhijit; Zhang, Pu; Azad, Abul; Wang, Wang; Wang, Xiuhua; Murray, Allan G; Kassiri, Zamaneh

2017-08-01

Myocardial infarction (MI) results in loss of cardiomyocytes, adverse extracellular matrix (ECM) and structural remodeling, and left ventricular (LV) dilation and dysfunction. Tissue inhibitors of metalloproteinase (TIMPs) inhibit matrix metalloproteinases (MMPs), the main regulators of ECM turnover. TIMPs also have MMP-independent functions. TIMP3 levels are reduced in the heart within 24 h of MI in mice. We investigated if overexpression of TIMP3 post-MI limits adverse remodeling and LV dilation and dysfunction. MI was induced by left anterior descending coronary artery ligation in 10- to 12-wk-old male C57BL/6J mice, and adenoviral constructs expressing human (h)TIMP3 (Ad-hTIMP3) or no TIMP (Ad-Null) were injected in the peri-infarct zone (5.4 × 10 7 plaque-forming units/heart, 5 injections/heart). Cardiac function assessed by echocardiography showed improved LV physiology and reduced LV dilation after TIMP3 overexpression compared with the Ad-Null-MI group. Post-MI adverse remodeling was attenuated in the Ad-hTIMP3-MI group, as assessed by greater cardiomyocyte density, less infarct expansion, and ECM disruption. TIMP3 overexpression blunted the early rise in proteolytic activities post-MI. A higher density of coronary arteries and a greater number of proliferating endothelial cells were detected in the infarct and peri-infarct regions in the Ad-hTIMP3-MI group compared with the Ad-Null-MI group. In vitro three-dimensional angiogenesis assay confirmed that recombinant TIMP3 promotes angiogenesis in human endothelial cells, although biphasically and in a dose-dependent manner. Intriguingly, overexpression of Ad-hTIMP3 at 10-fold higher concentration had no beneficial effects, consistent with antiangiogenic effects of TIMP3 at higher doses. In conclusion, optimal overexpression of TIMP3 can be a promising therapeutic approach to limit adverse post-MI remodeling by dually inhibiting early proteolysis and promoting angiogenesis. NEW & NOTEWORTHY Here, we report

The influence of glucagon on postprandial hyperglycaemia in children 5 years after onset of type 1 diabetes

DEFF Research Database (Denmark)

Fredheim, Siri; Andersen, Marie-Louise M; Pörksen, Sven

2015-01-01

comprised 129 children (66 boys) with type 1 diabetes whose mean (SD) age at onset was 10.0 (3.9) years. Liquid mixed-meal tests were performed prospectively at 1, 3, 6 and 12 months and a subset of 40 patients completed follow-up at 60 months. Postprandial (90 min) plasma levels of glucagon, glucose (PG......AIMS/HYPOTHESIS: The influence of glucagon on glycaemic control in type 1 diabetes is debated. We investigated the relationship between postprandial glucagon levels and HbA1c during a period up to 60 months after diagnosis of childhood type 1 diabetes. METHODS: The Danish remission phase cohort...... function in the first 5 years after diagnosis of type 1 diabetes. The positive association of glucagon with total GLP-1 and PG suggests that physiological regulation of alpha cell secretion in type 1 diabetes is seriously disturbed....

Toxoplasma gondii infection shifts dendritic cells into an amoeboid rapid migration mode encompassing podosome dissolution, secretion of TIMP-1, and reduced proteolysis of extracellular matrix.

Science.gov (United States)

Ólafsson, Einar B; Varas-Godoy, Manuel; Barragan, Antonio

2018-03-01

Dendritic cells (DCs) infected by Toxoplasma gondii rapidly acquire a hypermigratory phenotype that promotes systemic parasite dissemination by a "Trojan horse" mechanism in mice. Recent paradigms of leukocyte migration have identified the amoeboid migration mode of DCs as particularly suited for rapid locomotion in extracellular matrix and tissues. Here, we have developed a microscopy-based high-throughput approach to assess motility and matrix degradation by Toxoplasma-challenged murine and human DCs. DCs challenged with T. gondii exhibited dependency on metalloproteinase activity for hypermotility and transmigration but, strikingly, also dramatically reduced pericellular proteolysis. Toxoplasma-challenged DCs up-regulated expression and secretion of tissue inhibitor of metalloproteinases-1 (TIMP-1) and their supernatants impaired matrix degradation by naïve DCs and by-stander DCs dose dependently. Gene silencing of TIMP-1 by short hairpin RNA restored matrix degradation activity in Toxoplasma-infected DCs. Additionally, dissolution of podosome structures in parasitised DCs coincided with abrogated matrix degradation. Toxoplasma lysates inhibited pericellular proteolysis in a MyD88-dependent fashion whereas abrogated proteolysis persevered in Toxoplasma-infected MyD88-deficient DCs. This indicated that both TLR/MyD88-dependent and TLR/MyD88-independent signalling pathways mediated podosome dissolution and the abrogated matrix degradation. We report that increased TIMP-1 secretion and cytoskeletal rearrangements encompassing podosome dissolution are features of Toxoplasma-induced hypermigration of DCs with an impact on matrix degradation. Jointly, the data highlight how an obligate intracellular parasite orchestrates key regulatory cellular processes consistent with non-proteolytic amoeboid migration of the vehicle cells that facilitate its dissemination. © 2017 John Wiley & Sons Ltd.

Complete sequences of glucagon-like peptide-1 from human and pig small intestine

DEFF Research Database (Denmark)

Orskov, C; Bersani, M; Johnsen, A H

1989-01-01

intestine of the proglucagon precursor were determined by pairs of basic amino acid residues flanking the two peptides. Earlier studies have shown that synthetic glucagon-like peptide-1 (GLP-1) synthesized according to the proposed structure (proglucagon 71-108 or because residue 108 is Gly, 72-107 amide......) had no physiological effects, whereas a truncated from of GLP-1, corresponding to proglucagon 78-107 amide, strongly stimulated insulin secretion and depressed glucagon secretion. To determine the amino acid sequence of the naturally occurring peptide we isolated GLP-1 from human small intestine...

Granzyme B-dependent proteolysis acts as a switch to enhance the proinflammatory activity of IL-1α.

LENUS (Irish Health Repository)

Afonina, Inna S

2011-10-21

Granzyme B is a cytotoxic lymphocyte-derived protease that plays a central role in promoting apoptosis of virus-infected target cells, through direct proteolysis and activation of constituents of the cell death machinery. However, previous studies have also implicated granzymes A and B in the production of proinflammatory cytokines, via a mechanism that remains undefined. Here we show that IL-1α is a substrate for granzyme B and that proteolysis potently enhanced the biological activity of this cytokine in vitro as well as in vivo. Consistent with this, compared with full-length IL-1α, granzyme B-processed IL-1α exhibited more potent activity as an immunoadjuvant in vivo. Furthermore, proteolysis of IL-1α within the same region, by proteases such as calpain and elastase, was also found to enhance its biological potency. Thus, IL-1α processing by multiple immune-related proteases, including granzyme B, acts as a switch to enhance the proinflammatory properties of this cytokine.

Lysosomal proteolysis and autophagy require presenilin 1 and are disrupted by Alzheimer-related PS1 mutations.

Science.gov (United States)

Lee, Ju-Hyun; Yu, W Haung; Kumar, Asok; Lee, Sooyeon; Mohan, Panaiyur S; Peterhoff, Corrinne M; Wolfe, Devin M; Martinez-Vicente, Marta; Massey, Ashish C; Sovak, Guy; Uchiyama, Yasuo; Westaway, David; Cuervo, Ana Maria; Nixon, Ralph A

2010-06-25

Macroautophagy is a lysosomal degradative pathway essential for neuron survival. Here, we show that macroautophagy requires the Alzheimer's disease (AD)-related protein presenilin-1 (PS1). In PS1 null blastocysts, neurons from mice hypomorphic for PS1 or conditionally depleted of PS1, substrate proteolysis and autophagosome clearance during macroautophagy are prevented as a result of a selective impairment of autolysosome acidification and cathepsin activation. These deficits are caused by failed PS1-dependent targeting of the v-ATPase V0a1 subunit to lysosomes. N-glycosylation of the V0a1 subunit, essential for its efficient ER-to-lysosome delivery, requires the selective binding of PS1 holoprotein to the unglycosylated subunit and the Sec61alpha/oligosaccharyltransferase complex. PS1 mutations causing early-onset AD produce a similar lysosomal/autophagy phenotype in fibroblasts from AD patients. PS1 is therefore essential for v-ATPase targeting to lysosomes, lysosome acidification, and proteolysis during autophagy. Defective lysosomal proteolysis represents a basis for pathogenic protein accumulations and neuronal cell death in AD and suggests previously unidentified therapeutic targets.

Catalase rs769214 SNP in elderly malnutrition and during renutrition: is glucagon to blame?

Science.gov (United States)

Hebert-Schuster, M; Cottart, C H; Laguillier-Morizot, C; Raynaud-Simon, A; Golmard, J L; Cynober, L; Beaudeux, J L; Fabre, E E; Nivet-Antoine, V

2011-10-15

Impaired glucose tolerance is common during aging. The transcription factor PAX6 is involved in glucose homeostasis. Computational promoter sequence analysis of the catalase gene highlighted a putative PAX6 binding site on the rs769214 polymorphism A allele. Creation of this binding site has been suggested to explain renutrition inefficiency in malnourished elderly patients. Our aim was to evaluate the link between the rs769214 polymorphism of the catalase gene and glucose homeostasis in malnourished elderly patients at inclusion and during renutrition. Thirty-three malnourished elderly Caucasian inpatients were recruited. Nutritional and inflammatory statuses were assessed and a multiplex adipokine analysis was conducted at inclusion and discharge from the Geriatric Nutritional Care Unit at Charles-Foix Hospital (Ivry-sur-Seine, France). Serum glucagon, PAI-1, and TNF-α levels were significantly lower in the A-allele carriers at inclusion. During renutrition, A-allele carriers exhibited increased serum glucagon, PAI-1, and TNF-α variation. After renutrition, levels of these parameters were similar for A-allele carriers and G-allele carriers. A logistic ordinal multivariate regression analysis linked only variation of glucagon to rs769214 SNP. These results support a role for catalase SNP in the efficiency of renutrition in malnourished elderly patients via the modulation of glucagon secretion, probably involving PAX6. Copyright © 2011 Elsevier Inc. All rights reserved.

Polymorphism, metastable species and interconversion: the many states of glucagon fibrils

DEFF Research Database (Denmark)

Ghodke, Shirin D; Jensen, Grethe Vestergaard; Svane, Anna Sigrid P.

2014-01-01

physicochemical conditions such as high temperature, pressure, mechanical and chemical stress. Factors such as peptide concentration, accessible surface area, surface hydration of the glucagon molecular state, contact surface, temperature and ionic strength all contribute to fibrillar structure and stability...... fibril upon incubation at elevated temperatures (but not vice versa), indicating that fibrils are fundamentally malleable if they have not attained the most stable fibrillar state. While the effect of pressure on glucagon is complex (accelerating fibrillation at intermediate pressures and decelerating...... it at higher pressures), the thermal expansion coefficients obtained from these studies agree well with our previous calorimetric studies to reveal reduced or increased hydration of fibrils (leading to reduced or increased stability) depending on fibrillation conditions. Finally, we report...

Treating Severe Hypoglycemia: Rapid Mixing of Lyophilized Glucagon and Diluent at Point of Care With the Enject GlucaPen

OpenAIRE

Rylander, Dick

2014-01-01

Severe hypoglycemia (SH) is a common problem in type 1 diabetes (T1D). Annually, nearly 1 of 5 persons with long-standing T1D will have SH. Though injections of glucagon are effective in treating SH, liquid formulations of glucagon are biochemically very unstable. For this reason, available preparations of glucagon are lyophilized; the powder and the diluent must be mixed at the point of care prior to administration and any remaining drug must be discarded. The process of mixing and delivery ...

Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus

Directory of Open Access Journals (Sweden)

Grzegorz eWiera

2015-11-01

Full Text Available Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed LTP that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tPA/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1 and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.

Preserved inhibitory potency of GLP-1 on glucagon secretion in type 2 diabetes mellitus

DEFF Research Database (Denmark)

Hare, Kristine J; Knop, Filip K; Asmar, Meena

2009-01-01

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) is insulinotropic, but its effect on the alpha-cell is less clear. We investigated the dose-response relationship for GLP-1-induced glucagon suppression in patients with type 2 diabetes (T2DM) and healthy controls. DESIGN: Ten patients with T2DM (duration...... to d 2 (1733 +/- 193 3h x pmol/liter; P 2DM. A similar reduction in AUC for glucagon was observed in healthy controls [1122 +/- 186 (d 1) vs. 1733 +/- 312 3h x pmol/liter (d 2); P diabetic alpha-cell appears to be highly sensitive to the inhibitory...... of DM, 4 +/- 1 yr; glycosylated hemoglobin, 7.1 +/- 0.3%) were studied on 2 d, with stepwise increasing GLP-1 infusions (0.25, 0.5, 1.0, and 2.0 pmol x kg(-1) x min(-1)) (d 1) or saline (d 2) with plasma glucose (PG) clamped at fasting level. On d 3, patient PG was normalized overnight using a variable...

Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production

DEFF Research Database (Denmark)

Wewer Albrechtsen, Nicolai J.; Kuhre, Rune E.; Hornburg, Daniel

2017-01-01

that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in......Glucagon is secreted from pancreatic α cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among...... which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β cells demonstrated...

Colon distension, perceived burden and side-effects of CT-colonography for screening using hyoscine butylbromide or glucagon hydrochloride as bowel relaxant

International Nuclear Information System (INIS)

Haan, Margriet C. de; Boellaard, Thierry N.; Bossuyt, Patrick M.; Stoker, Jaap

2012-01-01

Objective: Compare colonic distension and perceived burden of CT-colonography between participants receiving hyoscine butylbromide (buscopan) and glucagon hydrochloride as bowel relaxant. Materials and methods: Data were collected within a screening trial. Participants received 20 mg buscopan intravenously or 1 mg of glucagon intravenously (if buscopan contra-indicated). Colon distension per segment was assessed using a 4-point scale (prone and supine). Data on perceived burden of CT-colonography were collected using a questionnaire two weeks after the examination. Outcome measures between groups were compared using propensity score matching. We used a stratified Wilcoxon–Mann–Whitney test statistic for quantitative and Cochran–Mantel–Haenszel statistics for categorical variables. Results: 541 participants were included: 336 (62%) received buscopan and 205 received glucagon. All buscopan recipients had an adequately distended colon, compared to 96% in the glucagon group (RR 7.31, 95% CI: 1.61–33.28). More glucagon recipients scored the insufflation as rather or extremely burdensome (25% vs. 16%; overall mean score 2.7 vs. 2.4; p < 0.001) and more found the entire CT-colonography rather or extremely burdensome (14% vs. 7%; 2.2 vs. 1.9; p = 0.001). Most frequently reported side effects were a dry mouth in the buscopan group (15%) and nausea in the glucagon group (13%). Conclusion: Compared to glucagon, premedication with buscopan results in significantly more adequately distended colons and a less burdensome procedure. When buscopan can be used, it is the preferred bowel relaxant.

Colon distension, perceived burden and side-effects of CT-colonography for screening using hyoscine butylbromide or glucagon hydrochloride as bowel relaxant

Energy Technology Data Exchange (ETDEWEB)

Haan, Margriet C. de, E-mail: margrietcdehaan@gmail.com [Department of Radiology, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Boellaard, Thierry N., E-mail: t.n.boellaard@amc.uva.nl [Department of Radiology, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Bossuyt, Patrick M., E-mail: p.m.bossuyt@amc.uva.nl [Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Stoker, Jaap, E-mail: j.stoker@amc.uva.nl [Department of Radiology, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands)

2012-08-15

Objective: Compare colonic distension and perceived burden of CT-colonography between participants receiving hyoscine butylbromide (buscopan) and glucagon hydrochloride as bowel relaxant. Materials and methods: Data were collected within a screening trial. Participants received 20 mg buscopan intravenously or 1 mg of glucagon intravenously (if buscopan contra-indicated). Colon distension per segment was assessed using a 4-point scale (prone and supine). Data on perceived burden of CT-colonography were collected using a questionnaire two weeks after the examination. Outcome measures between groups were compared using propensity score matching. We used a stratified Wilcoxon-Mann-Whitney test statistic for quantitative and Cochran-Mantel-Haenszel statistics for categorical variables. Results: 541 participants were included: 336 (62%) received buscopan and 205 received glucagon. All buscopan recipients had an adequately distended colon, compared to 96% in the glucagon group (RR 7.31, 95% CI: 1.61-33.28). More glucagon recipients scored the insufflation as rather or extremely burdensome (25% vs. 16%; overall mean score 2.7 vs. 2.4; p < 0.001) and more found the entire CT-colonography rather or extremely burdensome (14% vs. 7%; 2.2 vs. 1.9; p = 0.001). Most frequently reported side effects were a dry mouth in the buscopan group (15%) and nausea in the glucagon group (13%). Conclusion: Compared to glucagon, premedication with buscopan results in significantly more adequately distended colons and a less burdensome procedure. When buscopan can be used, it is the preferred bowel relaxant.

Nutrient-induced glucagon like peptide-1 release is modulated by serotonin.

Science.gov (United States)

Ripken, Dina; van der Wielen, Nikkie; Wortelboer, Heleen M; Meijerink, Jocelijn; Witkamp, Renger F; Hendriks, Henk F J

2016-06-01

Glucagon like peptide-1 (GLP-1) and serotonin are both involved in food intake regulation. GLP-1 release is stimulated upon nutrient interaction with G-protein coupled receptors by enteroendocrine cells (EEC), whereas serotonin is released from enterochromaffin cells (ECC). The central hypothesis for the current study was that nutrient-induced GLP-1 release from EECs is modulated by serotonin through a process involving serotonin receptor interaction. This was studied by assessing the effects of serotonin reuptake inhibition by fluoxetine on nutrient-induced GLP-1, PYY and CCK release from isolated pig intestinal segments. Next, serotonin-induced GLP-1 release was studied in enteroendocrine STC-1 cells, where effects of serotonin receptor inhibition were studied using specific and non-specific antagonists. Casein (1% w/v), safflower oil (3.35% w/v), sucrose (50mM) and rebaudioside A (12.5mM) stimulated GLP-1 release from intestinal segments, whereas casein only stimulated PYY and CCK release. Combining nutrients with fluoxetine further increased nutrient-induced GLP-1, PYY and CCK release. Serotonin release from intestinal tissue segments was stimulated by casein and safflower oil while sucrose and rebaudioside A had no effect. The combination with fluoxetine (0.155μM) further enhanced casein and safflower oil induced-serotonin release. Exposure of ileal tissue segments to serotonin (30μM) stimulated GLP-1 release whereas it did not induce PYY and CCK release. Serotonin (30 and 100μM) also stimulated GLP-1 release from STC-1 cells, which was inhibited by the non-specific 5HT receptor antagonist asenapine (1 and 10μM). These data suggest that nutrient-induced GLP-1 release is modulated by serotonin through a receptor mediated process. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Aberrant expression of glucagon receptors in adrenal glands of a patient with Cushing's syndrome and ACTH-independent macronodular adrenal hyperplasia

Directory of Open Access Journals (Sweden)

Valeria de Miguel

2010-06-01

Full Text Available Adrenocorticotropin (ACTH independent bilateral macronodular adrenal hyperplasia (AIMAH is a rare cause of Cushing´s syndrome, characterized by bilateral adrenal lesions and excess cortisol production despite ACTH suppression. Cortisol synthesis is produced in response to abnormal activation of G-protein- coupled receptors, such as gastric inhibitory peptide, vasopressin, beta adrenergic agonists, LH/hCG and serotonin receptors. The aim of this study was to analyze the expression of glucagon receptors in adrenal glands from an AIMAH patient. A patient with ACTH-independent Cushing´s syndrome and bilateral macronodular adrenal hyperplasia was screened for altered activation of adrenal receptors by physiological (mixed meal and pharmacological (gonadotrophin releasing hormone, ACTH and glucagon tests. The results showed abnormally high levels of serum cortisol after stimulation with glucagon. Hypercortisolism was successfully managed with ketoconazole treatment. Interestingly, a 4-month treatment with a somatostatin analogue (octreotide was also able to reduce cortisol secretion. Finally, Cushing's syndrome was cured after bilateral adrenalectomy. Abnormal mRNA expression for glucagon receptor in the patient´s adrenal glands was observed by Real-Time PCR procedure. These results strongly suggest that the mechanism of AIMAH causing Cushing´s syndrome in this case involves the illicit activation of adrenal glucagon receptors. This is the first case reported of AIMAH associated with ectopic glucagon receptors.

Neural regulation of glucagon-like peptide-1 secretion in pigs

DEFF Research Database (Denmark)

Hansen, Lene; Lampert, Sarah; Mineo, Hitoshi

2004-01-01

Glucagon-like peptide (GLP)-1 is secreted rapidly from the intestine postprandially. We therefore investigated its possible neural regulation. With the use of isolated perfused porcine ileum, GLP-1 secretion was measured in response to electrical stimulation of the mixed, perivascular nerve supply...

Immunocytochemical detection of glucagon and insulin cells in endocrine pancreas and cyclic disparity of plasma glucose in the turtle Melanochelys trijuga.

Science.gov (United States)

Chandavar, Vidya R; Naik, Prakash R

2008-06-01

The present investigation was carried out to know the seasonal variation in plasma glucose,insulin and glucagon cells during the reproductive cycle of untreated Melanochelys trijuga. Pancreatic endocrine cells were immunochemically localized.Insulin-immunoreactive (IR) cells occurred in groups of 3-20 and were in close apposition, while glucagon-IR cells were distributed individually between the exocrine pancreas or formed anastomosing cords where cells were not intimately attached. Whenever both IR cell types were present together forming an islet,insulin-IR cells formed clusters in the centre with glucagon-IR cells being scattered at the periphery. Glucagon-IR cells seemed to be secretory throughout the pancreas during the reproductive cycle,while insulin-IR cells were found to be pulsating in their secretion. Mean size of the islet was 1.306, 0.184 and 2.558 mm in the regenerative, reproductive and regressive periods,respectively. In general,insulin-IR cells measured 5.18 (mu)m and glucagon-IR cells 5.22 (mu)m in their longest axis. Invariably, glucagon-IR cells were more in number than insulin-IR cells. The fasting plasma glucose level was 69.97 mg% during the regenerative period, which increased to 97.96 mg% during the reproductive period,and reached a peak value of 113.52 mg% in the regressive period.

Immunohistochemical expression of insulin, glucagon, and somatostatin in pancreatic islets of horses with and without insulin resistance.

Science.gov (United States)

Newkirk, Kim M; Ehrensing, Gordon; Odoi, Agricola; Boston, Raymond C; Frank, Nicholas

2018-02-01

OBJECTIVE To assess insulin, glucagon, and somatostatin expression within pancreatic islets of horses with and without insulin resistance. ANIMALS 10 insulin-resistant horses and 13 insulin-sensitive horses. PROCEDURES For each horse, food was withheld for at least 10 hours before a blood sample was collected for determination of serum insulin concentration. Horses with a serum insulin concentration horses with a serum insulin concentration > 20 μU/mL underwent a frequently sampled IV glucose tolerance test to determine sensitivity to insulin by minimal model analysis. Horses with a sensitivity to insulin horses were euthanized with a barbiturate overdose, and pancreatic specimens were harvested and immunohistochemically stained for determination of insulin, glucagon, and somatostatin expression in pancreatic islets. Islet hormone expression was compared between insulin-resistant and insulin-sensitive horses. RESULTS Cells expressing insulin, glucagon, and somatostatin made up approximately 62%, 12%, and 7%, respectively, of pancreatic islet cells in insulin-resistant horses and 64%, 18%, and 9%, respectively, of pancreatic islet cells in insulin-sensitive horses. Expression of insulin and somatostatin did not differ between insulin-resistant and insulin-sensitive horses, but the median percentage of glucagon-expressing cells in the islets of insulin-resistant horses was significantly less than that in insulin-sensitive horses. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that, in insulin-resistant horses, insulin secretion was not increased but glucagon production might be downregulated as a compensatory response to hyperinsulinemia.

Glucagon-like peptide-1, glucose homeostasis and diabetes

DEFF Research Database (Denmark)

Holst, Jens Juul; Deacon, Carolyn F; Vilsbøll, Tina

2008-01-01

Incretins, enhancers of insulin secretion, are essential for glucose tolerance, and a reduction in their function might contribute to poor beta-cell function in patients with type-2 diabetes mellitus. However, at supraphysiological doses, the incretin glucagon-like peptide-1 (GLP-1) protects...... as therapies for type-2 diabetes and have recently reached the market. The pathophysiological basis the clinical use of these therapeutics is reviewed here....

Cross-Validation of a Glucose-Insulin-Glucagon Pharmacodynamics Model for Simulation using Data from Patients with Type 1 Diabetes

DEFF Research Database (Denmark)

Wendt, Sabrina Lyngbye; Ranjan, Ajenthen; Møller, Jan Kloppenborg

2017-01-01

three PD model test fits in each of the seven subjects. Thus, we successfully validated the PD model by leave-one-out cross-validation in seven out of eight T1D patients. Conclusions: The PD model accurately simulates glucose excursions based on plasma insulin and glucagon concentrations. The reported...... for concentrations of glucagon, insulin, and glucose. We fitted pharmacokinetic (PK) models to insulin and glucagon data using maximum likelihood and maximum a posteriori estimation methods. Similarly, we fitted a pharmacodynamic (PD) model to glucose data. The PD model included multiplicative effects of insulin...... and glucagon on EGP. Bias and precision of PD model test fits were assessed by mean predictive error (MPE) and mean absolute predictive error (MAPE). Results: Assuming constant variables in a subject across nonoutlier visits and using thresholds of ±15% MPE and 20% MAPE, we accepted at least one and at most...

Bystander protein protects potential vaccine-targeting ligands against intestinal proteolysis.

Science.gov (United States)

Reuter, Fabian; Bade, Steffen; Hirst, Timothy R; Frey, Andreas

2009-07-20

Endowing mucosal vaccines with ligands that target antigen to mucosal lymphoid tissues may improve immunization efficacy provided that the ligands withstand the proteolytic environment of the gastro-intestinal tract until they reach their destination. Our aim was to investigate whether and how three renowned ligands - Ulex europaeus agglutinin I and the B subunits of cholera toxin and E. coli heat-labile enterotoxin - master this challenge. We assessed the digestive power of natural murine intestinal fluid (natIF) using assays for trypsin, chymotrypsin and pancreatic elastase along with a test for nonspecific proteolysis. The natIF was compared with simulated murine intestinal fluid (simIF) that resembled the trypsin, chymotrypsin and elastase activities of its natural counterpart but lacked or contained albumins as additional protease substrates. The ligands were exposed to the digestive fluids and degradation was determined. The studies revealed that (i) the three pancreatic endoproteases constitute only one third of the total protease activity of natIF and (ii) the ligands resist proteolysis in natIF and protein-enriched simIF over 3 h but (iii) are partially destroyed in simIF that lacks additional protease substrate. We assume that the proteins of natIF are preferred substrates for the intestinal proteases and thus can protect vaccine-targeting ligands from destruction.

Decreased rate of protein synthesis, caspase-3 activity, and ubiquitin-proteasome proteolysis in soleus muscles from growing rats fed a low-protein, high-carbohydrate diet.

Science.gov (United States)

Batistela, Emanuele; Pereira, Mayara Peron; Siqueira, Juliany Torres; Paula-Gomes, Silvia; Zanon, Neusa Maria; Oliveira, Eduardo Brandt; Navegantes, Luiz Carlos Carvalho; Kettelhut, Isis C; Andrade, Claudia Marlise Balbinotti; Kawashita, Nair Honda; Baviera, Amanda Martins

2014-06-01

The aim of this study was to investigate the changes in the rates of both protein synthesis and breakdown, and the activation of intracellular effectors that control these processes in soleus muscles from growing rats fed a low-protein, high-carbohydrate (LPHC) diet for 15 days. The mass and the protein content, as well as the rate of protein synthesis, were decreased in the soleus from LPHC-fed rats. The availability of amino acids was diminished, since the levels of various essential amino acids were decreased in the plasma of LPHC-fed rats. Overall rate of proteolysis was also decreased, explained by reductions in the mRNA levels of atrogin-1 and MuRF-1, ubiquitin conjugates, proteasome activity, and in the activity of caspase-3. Soleus muscles from LPHC-fed rats showed increased insulin sensitivity, with increased levels of insulin receptor and phosphorylation levels of AKT, which probably explains the inhibition of both the caspase-3 activity and the ubiquitin-proteasome system. The fall of muscle proteolysis seems to represent an adaptive response that contributes to spare proteins in a condition of diminished availability of dietary amino acids. Furthermore, the decreased rate of protein synthesis may be the driving factor to the lower muscle mass gain in growing rats fed the LPHC diet.

[Study on correlation of glucagons, type 2 diabetes and impaired glucose regulation].

Science.gov (United States)

Xu, Tao; Shi, Me; Qiu, Yun-Xia; Wang, Yan-Gang

2014-06-01

To analyze the changes of patients with type 2 diabetes in different stages in glucagon (GC) and free fatty acid (FFA) in fasting, OGT and L-Arg experiments, and discusses the role of pancreatic alphabeta cells in diabetes pathogenesis by studying the relations among indexes such as glucagon (GC), free fatty acid (FFA) and blood glucose (BG), insulin, insulin homeostasis model (HOMA) and glucose metabolism hormone secretion curve, in order to provide theoretical basis for the treatment of diabetes. Study objects were divided into the T2DM group (45 cases), the IGT group (28 cases) and the NGT group (30 cases) for an OGTT experiment and then an L-Arg experiment on the next day. Under the fasting state, their blood glucose (FBG), insulin (F), glucagon (FGC), free fatty acid (FFA) were detected to calculate HOMA-beta, insulin sensitivity index (ISI) and HOMA-IR of different groups. Meanwhile, efforts were made to calculate different time quantum detected in OGTT and L-Arg experiments and area under the curve AUC(BG), AUC(INS) and AUC(GC). Obvious overall differences were observed in FFA and FGC of the three groups. FGC of each group was negatively correlated with HOMA-beta and ISI. Among all of the 103 study objects, FGC was positively correlated with FBG and HOMA-IR and negatively correlated with HOMA-beta and ISI, with no correlation with FINS; FFA was positively correlated with FBG, HOMA-IR and negatively correlated with FINS, HOMA-beta, ISI. FGC and FFA were positively correlated in the T2DM group and the IGT group, but with no statistical correlation in the NGT group. The sequence of the three study objects was T2DM > IGR > NGT in AUC(GC) in the OGTT experiment and T2DM > IGR > NGT in in AUC(GC) in the L-Arg experiment, with the significant positive correlation between AUC(GC) and AUC(BG) and significant negative correlation with AUC(INS). Glucagon and free fatty acid of T2DM and IGT patients increased, which was positively correlated with blood glucose and HOMA

Meal-stimulated glucagon release is associated with postprandial blood glucose level and does not interfere with glycemic control in children and adolescents with new-onset type 1 diabetes

DEFF Research Database (Denmark)

Pörksen, Sven; Nielsen, Lotte B; Kaas, Anne

2007-01-01

The role of glucagon in hyperglycemia in type 1 diabetes is unresolved, and in vitro studies suggest that increasing blood glucose might stimulate glucagon secretion.......The role of glucagon in hyperglycemia in type 1 diabetes is unresolved, and in vitro studies suggest that increasing blood glucose might stimulate glucagon secretion....

Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism

DEFF Research Database (Denmark)

Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob

2018-01-01

The relationship between gut and skeleton is increasingly recognised as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibi......-clinical investigations, clinical trials are needed to clarify if similar effects are present and clinically relevant in humans. This article is protected by copyright. All rights reserved....

Role of calpain in eccentric contraction-induced proteolysis of Ca2+-regulatory proteins and force depression in rat fast-twitch skeletal muscle.

Science.gov (United States)

Kanzaki, Keita; Watanabe, Daiki; Kuratani, Mai; Yamada, Takashi; Matsunaga, Satoshi; Wada, Masanobu

2017-02-01

The aim of this study was to examine the in vivo effects of eccentric contraction (ECC) on calpain-dependent proteolysis of Ca 2+ -regulatory proteins and force production in fast-twitch skeletal muscles. Rat extensor digitorum longus muscles were exposed to 200 repeated ECC in situ and excised immediately [recovery 0 (REC0)] or 3 days [recovery 3 (REC3)] after cessation of ECC. Calpain inhibitor (CI)-treated rats were intraperitoneally injected with MDL-28170 before ECC and during REC3. Tetanic force was markedly reduced at REC0 and remained reduced at REC3. CI treatment ameliorated the ECC-induced force decline but only at REC3. No evidence was found for proteolysis of dihydropyridine receptor (DHPR), junctophilin (JP)1, JP2, ryanodine receptor (RyR), sarcoplasmic reticulum Ca 2+ -ATPase (SERCA)1a, or junctional face protein-45 at REC0. At REC3, ECC resulted in decreases in DHPR, JP1, JP2, RyR, and SERCA1a. CI treatment prevented the decreases in DHPR, JP1, and JP2, whereas it had little effect on RyR and SERCA1a. These findings suggest that DHPR, JP1, and JP2, but not RyR and SERCA1a, undergo calpain-dependent proteolysis in in vivo muscles subjected to ECC and that impaired function of DHPR and/or JP might cause prolonged force deficits with ECC. NEW & NOTEWORTHY Calpain-dependent proteolysis is one of the contributing factors to muscle damage that occurs with eccentric contraction (ECC). It is unclear, however, whether calpains account for proteolysis of Ca 2+ -regulatory proteins in in vivo muscles subjected to ECC. Here, we provide evidence that dihydropyridine receptor and junctophilin, but not ryanodine receptor and sarcoplasmic reticulum Ca 2+ -ATPase, undergo calpain-dependent proteolysis. Copyright © 2017 the American Physiological Society.

Glucagon receptor knockout mice are protected against acute olanzapine-induced hyperglycemia.

Science.gov (United States)

Castellani, Laura N; Peppler, Willem T; Sutton, Charles D; Whitfield, Jamie; Charron, Maureen J; Wright, David C

2017-08-01

To determine if glucagon is involved in mediating the increase in blood glucose levels caused by the second-generation antipsychotic drug olanzapine. Whole body glucagon receptor deficient mice (Gcgr -/- ) or WT littermate controls were injected with olanzapine (5mg/kg BW IP) and changes in blood glucose measured over the following 120min. Separate cohorts of mice were treated with olanzapine and changes in pyruvate tolerance, insulin tolerance and whole body substrate oxidation were determined. Olanzapine treatment increased serum glucagon and lead to rapid increases in blood glucose concentrations in WT mice. Gcgr -/- mice were protected against olanzapine-induced increases in blood glucose but this was not explained by differences in terminal serum insulin concentrations, enhanced AKT phosphorylation in skeletal muscle, adipose tissue or liver or differences in RER. In both genotypes olanzapine induced an equivalent degree of insulin resistance as measured using an insulin tolerance test. Olanzapine treatment led to an exaggerated glucose response to a pyruvate challenge in WT but not Gcgr -/- mice and this was paralleled by reductions in the protein content of PEPCK and G6Pase in livers from Gcgr -/- mice. Gcgr -/- mice are protected against olanzapine-induced increases in blood glucose. This is likely a result of reductions in liver glucose output, perhaps secondary to decreases in PEPCK and G6Pase protein content. Our findings highlight the central role of the liver in mediating olanzapine-induced disturbances in glucose homeostasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thirty days of resveratrol supplementation does not affect postprandial incretin hormone responses, but suppresses postprandial glucagon in obese subjects

DEFF Research Database (Denmark)

Knop, F K; Konings, E; Timmers, S

2013-01-01

AIMS: Resveratrol, a natural polyphenolic compound produced by various plants (e.g. red grapes) and found in red wine, has glucose-lowering effects in humans and rodent models of obesity and/or diabetes. The mechanisms behind these effects have been suggested to include resveratrol......-induced secretion of the gut incretin hormone glucagon-like peptide-1. We investigated postprandial incretin hormone and glucagon responses in obese human subjects before and after 30 days of resveratrol supplementation. METHODS: Postprandial plasma responses of the incretin hormones glucagon-like peptide-1...... and glucose-dependent insulinotropic polypeptide and glucagon were evaluated in 10 obese men [subjects characteristics (mean ± standard error of the mean): age 52 ± 2 years; BMI 32 ± 1 kg/m(2) , fasting plasma glucose 5.5 ± 0.1 mmol/l] who had been given a dietary supplement of resveratrol (Resvida(®) 150 mg...

Possible contribution of taurine to distorted glucagon secretion in intra-islet insulin deficiency: a metabolome analysis using a novel α-cell model of insulin-deficient diabetes.

Directory of Open Access Journals (Sweden)

Megumi Bessho

Full Text Available Glycemic instability is a serious problem in patients with insulin-deficient diabetes, and it may be due in part to abnormal endogenous glucagon secretion. However, the intracellular metabolic mechanism(s involved in the aberrant glucagon response under the condition of insulin deficiency has not yet been elucidated. To investigate the metabolic traits that underlie the distortion of glucagon secretion under insulin deficient conditions, we generated an αTC1-6 cell line with stable knockdown of the insulin receptor (IRKD, i.e., an in vitro α-cell model for insulin-deficient diabetes, which exhibits an abnormal glucagon response to glucose. A comprehensive metabolomic analysis of the IRKD αTC1-6 cells (IRKD cells revealed some candidate metabolites whose levels differed markedly compared to those in control αTC1-6 cells, but also which could affect the glucagon release in IRKD cells. Of these candidates, taurine was remarkably increased in the IRKD cells and was identified as a stimulator of glucagon in αTC1-6 cells. Taurine also paradoxically exaggerated the glucagon secretion at a high glucose concentration in IRKD cells and islets with IRKD. These results indicate that the metabolic alterations induced by IRKD in α-cells, especially the increase of taurine, may lead to the distorted glucagon response in IRKD cells, suggesting the importance of taurine in the paradoxical glucagon response and the resultant glucose instability in insulin-deficient diabetes.

Glucagonostatic actions and reduction of fasting hyperglycemia by exogenous glucagon-like peptide I(7-36) amide in type I diabetic patients

DEFF Research Database (Denmark)

Creutzfeldt, W O; Kleine, N; Willms, B

1996-01-01

. kg-1 . min-1 GLP-1 or placebo was infused intravenously in the morning (plasma glucose 13.7 +/- 0.9 mmol/l; plasma insulin 26 +/- 4 pmol/l). Glucose (glucose oxidase method), insulin, C-peptide, glucagon, GLP-1, cortisol, growth hormone (immunoassays), triglycerides, cholesterol, and nonesterified......OBJECTIVE: Glucagon-like peptide I(7-36) amide (GLP-1) is a physiological incretin hormone that, in slightly supraphysiological doses, stimulates insulin secretion, lowers glucagon concentrations, and thereby normalizes elevated fasting plasma glucose concentrations in type II diabetic patients...... fatty acids (enzymatic tests) were measured. RESULTS: Glucagon was reduced from approximately 8 to 4 pmol/l, and plasma glucose was lowered from 13.4 +/- 1.0 to 10.0 +/- 1.2 mmol/l with GLP-1 administration (plasma concentrations approximately 100 pmol, P

Discovery of Anti-Hypertensive Oligopeptides from Adlay Based on In Silico Proteolysis and Virtual Screening

Directory of Open Access Journals (Sweden)

Liansheng Qiao

2016-12-01

Full Text Available Adlay (Coix larchryma-jobi L. was the commonly used Traditional Chinese Medicine (TCM with high content of seed storage protein. The hydrolyzed bioactive oligopeptides of adlay have been proven to be anti-hypertensive effective components. However, the structures and anti-hypertensive mechanism of bioactive oligopeptides from adlay were not clear. To discover the definite anti-hypertensive oligopeptides from adlay, in silico proteolysis and virtual screening were implemented to obtain potential oligopeptides, which were further identified by biochemistry assay and molecular dynamics simulation. In this paper, ten sequences of adlay prolamins were collected and in silico hydrolyzed to construct the oligopeptide library with 134 oligopeptides. This library was reverse screened by anti-hypertensive pharmacophore database, which was constructed by our research team and contained ten anti-hypertensive targets. Angiotensin-I converting enzyme (ACE was identified as the main potential target for the anti-hypertensive activity of adlay oligopeptides. Three crystal structures of ACE were utilized for docking studies and 19 oligopeptides were finally identified with potential ACE inhibitory activity. According to mapping features and evaluation indexes of pharmacophore and docking, three oligopeptides were selected for biochemistry assay. An oligopeptide sequence, NPATY (IC50 = 61.88 ± 2.77 µM, was identified as the ACE inhibitor by reverse-phase high performance liquid chromatography (RP-HPLC assay. Molecular dynamics simulation of NPATY was further utilized to analyze interactive bonds and key residues. ALA354 was identified as a key residue of ACE inhibitors. Hydrophobic effect of VAL518 and electrostatic effects of HIS383, HIS387, HIS513 and Zn2+ were also regarded as playing a key role in inhibiting ACE activities. This study provides a research strategy to explore the pharmacological mechanism of Traditional Chinese Medicine (TCM proteins based on

LSD1 demethylase and the methyl-binding protein PHF20L1 prevent SET7 methyltransferase-dependent proteolysis of the stem-cell protein SOX2.

Science.gov (United States)

Zhang, Chunxiao; Hoang, Nam; Leng, Feng; Saxena, Lovely; Lee, Logan; Alejo, Salvador; Qi, Dandan; Khal, Anthony; Sun, Hong; Lu, Fei; Zhang, Hui

2018-03-09

The pluripotency-controlling stem-cell protein SRY-box 2 (SOX2) plays a pivotal role in maintaining the self-renewal and pluripotency of embryonic stem cells and also of teratocarcinoma or embryonic carcinoma cells. SOX2 is monomethylated at lysine 119 (Lys-119) in mouse embryonic stem cells by the SET7 methyltransferase, and this methylation triggers ubiquitin-dependent SOX2 proteolysis. However, the molecular regulators and mechanisms controlling SET7-induced SOX2 proteolysis are unknown. Here, we report that in human ovarian teratocarcinoma PA-1 cells, methylation-dependent SOX2 proteolysis is dynamically regulated by the LSD1 lysine demethylase and a methyl-binding protein, PHD finger protein 20-like 1 (PHF20L1). We found that LSD1 not only removes the methyl group from monomethylated Lys-117 (equivalent to Lys-119 in mouse SOX2), but it also demethylates monomethylated Lys-42 in SOX2, a reaction that SET7 also regulated and that also triggered SOX2 proteolysis. Our studies further revealed that PHF20L1 binds both monomethylated Lys-42 and Lys-117 in SOX2 and thereby prevents SOX2 proteolysis. Down-regulation of either LSD1 or PHF20L1 promoted SOX2 proteolysis, which was prevented by SET7 inactivation in both PA-1 and mouse embryonic stem cells. Our studies also disclosed that LSD1 and PHF20L1 normally regulate the growth of pluripotent mouse embryonic stem cells and PA-1 cells by preventing methylation-dependent SOX2 proteolysis. In conclusion, our findings reveal an important mechanism by which the stability of the pluripotency-controlling stem-cell protein SOX2 is dynamically regulated by the activities of SET7, LSD1, and PHF20L1 in pluripotent stem cells. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Impaired crosstalk between pulsatile insulin and glucagon secretion in prediabetic individuals

DEFF Research Database (Denmark)

Rohrer, Stefan; Menge, Björn A; Grüber, Lena

2012-01-01

Postprandial hyperglucagonemia is frequently found in patients with diabetes. Recently, a loss of the inverse relationship between pulsatile insulin and glucagon secretion has been reported in patients with type 2 diabetes. The crosstalk between pulsatile islet hormone secretion in prediabetic...

Glucagon-like peptide-1 analogue prevents nonalcoholic steatohepatitis in non-obese mice.

Science.gov (United States)

Yamamoto, Takaya; Nakade, Yukiomi; Yamauchi, Taeko; Kobayashi, Yuji; Ishii, Norimitsu; Ohashi, Tomohiko; Ito, Kiyoaki; Sato, Ken; Fukuzawa, Yoshitaka; Yoneda, Masashi

2016-02-28

To investigate whether a glucagon-like peptide-1 (GLP-1) analogue inhibits nonalcoholic steatohepatitis (NASH), which is being increasingly recognized in Asia, in non-obese mice. A methionine-choline-deficient diet (MCD) along with exendin-4 (20 μg/kg per day, ip), a GLP-1 analogue, or saline was administered to male db/db mice (non-obese NASH model). Four or eight weeks after commencement of the diet, the mice were sacrificed and their livers were excised. The excised livers were examined by histochemistry for evidence of hepatic steatosis and inflammation. Hepatic triglyceride (TG) and free fatty acid (FFA) content was measured, and the expression of hepatic fat metabolism- and inflammation-related genes was evaluated. Oxidative stress-related parameters and macrophage recruitment were also examined using immunohistochemistry. Four weeks of MCD feeding induced hepatic steatosis and inflammation and increased the hepatic TG and FFA content. The expression of fatty acid transport protein 4 (FATP4), a hepatic FFA influx-related gene; macrophage recruitment; and the level of malondialdehyde (MDA), an oxidative stress marker, were significantly augmented by a 4-wk MCD. The levels of hepatic sterol regulatory element-binding protein-1c (SREBP-1c) mRNA (lipogenesis-related gene) and acyl-coenzyme A oxidase 1 (ACOX1) mRNA (β-oxidation-related gene) had decreased at 4 wk and further decreased at 8 wk. However, the level of microsomal triglyceride transfer protein mRNA (a lipid excretion-related gene) remained unchanged. The administration of exendin-4 significantly attenuated the MCD-induced increase in hepatic steatosis, hepatic TG and FFA content, and FATP4 expression as well as the MCD-induced augmentation of hepatic inflammation, macrophage recruitment, and MDA levels. Additionally, it further decreased the hepatic SREBP-1c level and alleviated the MCD-mediated inhibition of the ACOX1 mRNA level. These results suggest that GLP-1 inhibits hepatic steatosis and

Immunohistochemical localization of glucagon and pancreatic polypeptide on rat endocrine pancreas: coexistence in rat islet cells

Directory of Open Access Journals (Sweden)

YH Huang

2009-08-01

Full Text Available We used immunofluorescence double staining method to investigate the cellular localization of glucagon and pancreatic polypeptide (PP in rat pancreatic islets. The results showed that both A-cells (glucagon-secreting cells and PP-cells (PPsecreting cells were located in the periphery of the islets. However, A-cells and PP-cells had a different regional distribution. Most of A-cells were located in the splenic lobe but a few of them were in the duodenal lobe of the pancreas. In contrast, the majority of PP-cells were found in the duodenal lobe and a few of them were in the splenic lobe of the pancreas. Furthermore, we found that 67.74% A-cells had PP immunoreactivity, 70.92% PP-cells contained glucagon immunoreactivity with immunofluorescence double staining. Our data support the concept of a common precursor stem cell for pancreatic hormone-producing cells.

Yak milk casein as potential precursor of angiotensin I-converting enzyme inhibitory peptides based on in silico proteolysis.

Science.gov (United States)

Lin, Kai; Zhang, Lan-Wei; Han, Xue; Xin, Liang; Meng, Zhao-Xu; Gong, Pi-Min; Cheng, Da-You

2018-07-15

Yak milk casein was selected as a potential precursor of bioactive peptides based on in silico analysis. Most notable among these are the angiotensin I-converting enzyme (ACE) inhibitory peptides. First, yak milk casein has high homology with cow milk casein by homologous analysis. The potential of yak milk casein for the releasing bioactive peptides was evaluated by determining the frequency of occurrence of fragments with a given activity. Through the BIOPEP database analysis, there are many bioactive peptides in yak milk casein sequences. Then, an in silico proteolysis using single or combined enzymes to obtained ACE inhibitory peptides was investigated. Cytotoxicity analysis using the online toxic prediction tool ToxinPred revealed that all in silico proteolysis derived ACE inhibitory peptides are non-cytotoxic. Overall, the present study highlights a in silico proteolysis approach to assist the yak milk casein releasing ACE inhibitory peptides and provides a guidance for the actual hydrolysis of proteins for the production of bioactive peptides. Copyright © 2018 Elsevier Ltd. All rights reserved.

Glucagon increase after chronic AT₁ blockade is more likely related to an indirect leptin-dependent than to a pancreatic α-cell-dependent mechanism

DEFF Research Database (Denmark)

Mildner, Martin; Müller-Fielitz, Helge; Stölting, Ines

2017-01-01

II stimulation (0.01-100 μM) in α cells (InR1G9) and isolated murine islets. We determined plasma glucagon in rats that were chronically treated with AngII (9 μg/h) or the ARBs telmisartan (8 mg/kg/day) and candesartan (16 mg/kg/day) and correlated glucagon with additional hormones (e.g. leptin). Glucagon...... with AngII or candesartan and also when Sprague Dawley rats were treated with telmisartan in parallel to high-calorie feeding. Plasma glucagon and leptin negatively correlated in ARB-treated rats. The glucagon release from InR1G9 cells or islets after AngII, AngIV or Ang(1-7) is unspecific since it only...

Diacylglycerol acyltransferase-1 (DGAT1 inhibition perturbs postprandial gut hormone release.

Directory of Open Access Journals (Sweden)

Hua V Lin

Full Text Available Diacylglycerol acyltransferase-1 (DGAT1 is a potential therapeutic target for treatment of obesity and related metabolic diseases. However, the degree of DGAT1 inhibition required for metabolic benefits is unclear. Here we show that partial DGAT1 deficiency in mice suppressed postprandial triglyceridemia, led to elevations in glucagon-like peptide-1 (GLP-1 and peptide YY (PYY only following meals with very high lipid content, and did not protect from diet-induced obesity. Maximal DGAT1 inhibition led to enhanced GLP-1 and PYY secretion following meals with physiologically relevant lipid content. Finally, combination of DGAT1 inhibition with dipeptidyl-peptidase-4 (DPP-4 inhibition led to further enhancements in active GLP-1 in mice and dogs. The current study suggests that targeting DGAT1 to enhance postprandial gut hormone secretion requires maximal inhibition, and suggests combination with DPP-4i as a potential strategy to develop DGAT1 inhibitors for treatment of metabolic diseases.

Glucose-Dependent Insulinotropic Polypeptide Augments Glucagon Responses to Hypoglycemia in Type 1 Diabetes

DEFF Research Database (Denmark)

Christensen, Mikkel; Calanna, Salvatore; Sparre-Ulrich, Alexander H

2015-01-01

constituted a "recovery phase." During the recovery phase, GIP infusions elicited larger glucagon responses (164 ± 50 [GIP] vs. 23 ± 25 [GLP-1] vs. 17 ± 46 [saline] min ⋅ pmol/L, P endogenous glucose production was higher with GIP and lower with GLP-1 compared with saline (P ... days, significantly less exogenous glucose was needed to keep plasma glucose above 2 mmol/L (155 ± 36 [GIP] vs. 232 ± 40 [GLP-1] vs. 212 ± 56 [saline] mg ⋅ kg(-1), P ... similar on all days. Our results suggest that during hypoglycemia in patients with T1DM, exogenous GIP increases glucagon responses during the recovery phase after hypoglycemia and reduces the need for glucose administration....

Cell cycle- and cell growth-regulated proteolysis of mammalian CDC6 is dependent on APC-CDH1

DEFF Research Database (Denmark)

Petersen, B O; Wagener, C; Marinoni, F

2000-01-01

is targeted for ubiquitin-mediated proteolysis by the anaphase promoting complex (APC)/cyclosome in G(1). A combination of point mutations in the destruction box and KEN-box motifs in CDC6 stabilizes the protein in G(1) and in quiescent cells. Furthermore, APC, in association with CDH1, ubiquitinates CDC6...... in vitro, and both APC and CDH1 are required and limiting for CDC6 proteolysis in vivo. Although a stable mutant of CDC6 is biologically active, overexpression of this mutant or wild-type CDC6 is not sufficient to induce multiple rounds of DNA replication in the same cell cycle. The APC-CDH1-dependent...

Nutrient-induced glucagon like peptide-1 release is modulated by serotonin

NARCIS (Netherlands)

Ripken, D.; Wielen, N. van der; Wortelboer, H.M.; Meijerink, J.; Witkamp, R.F.; Hendriks, H.F.J.

2016-01-01

Glucagon like peptide-1 (GLP-1) and serotonin are both involved in food intake regulation. GLP-1 release is stimulated upon nutrient interaction with G-protein coupled receptors by enteroendocrine cells (EEC), whereas serotonin is released from enterochromaffin cells (ECC). The central hypothesis

Autophagic dysfunction in a lysosomal storage disorder due to impaired proteolysis

OpenAIRE

Elrick, Matthew J.; Lieberman, Andrew P.

2013-01-01

Alterations in macroautophagy (hereafter referred to as “autophagy”) are a common feature of lysosomal storage disorders, and have been hypothesized to play a major role in the pathogenesis of these diseases. We have recently reported multiple defects in autophagy contributing to the lysosomal storage disorder Niemann-Pick type C (NPC). These include increased formation of autophagosomes, slowed turnover of autophagosomes secondary to impaired lysosomal proteolysis, and delivery of stored lip...

Proteolysis of bovine beta-lactoglobulin during thermal treatment in subdenaturing conditions highlights some structural features of the temperature-modified protein and yields fragments with low immunoreactivity

DEFF Research Database (Denmark)

Iametti, S.; Rasmussen, P.; Frøkiær, Hanne

2002-01-01

Bovine beta-lactoglobulin was hydrolyzed with trypsin or chymotrypsin in the course of heat treatment at 55, 60 and 65 C at neutral pH. At these temperatures beta-lactoglobulin undergoes significant but reversible structural changes. In the conditions used in the present study, beta......-lactoglobulin was virtually insensitive to proteolysis by either enzyme at room temperature, but underwent extensive proteolysis when either protease was present during the heat treatment. High-temperature proteolysis occurs in a progressive manner. Mass spectrometry analysis of some large-sized breakdown intermediates...

Polymorphism of glucagon-like peptide-1 receptor gene (rs1042044 ...

African Journals Online (AJOL)

Previous investigations indicated that glucagon-like peptide-1 (GLP-1) played important roles in bone turnover via GLP-1 receptors (GLP1Rs) in postmenopausal state. Furthermore, polymorphisms in GLP1R gene were suggested to affect the function of GLP1Rs and be associated with many diseases. However, the ...

The fluctuation of blood glucose, insulin and glucagon concentrations before and after insulin therapy in type 1 diabetes

Science.gov (United States)

Arif, Idam; Nasir, Zulfa

2015-09-01

A dynamical-systems model of plasma glucose, insulin and glucagon concentrations has been developed to investigate the effects of insulin therapy on blood glucose, insulin and glucagon regulations in type 1 diabetic patients. Simulation results show that the normal regulation of blood glucose concentration depends on insulin and glucagon concentrations. On type 1 diabetic case, the role of insulin on regulating blood glucose is not optimal because of the destruction of β cells in pancreas. These β cells destructions cause hyperglycemic episode affecting the whole body metabolism. To get over this, type 1 diabetic patients need insulin therapy to control the blood glucose level. This research has been done by using rapid acting insulin (lispro), long-acting insulin (glargine) and the combination between them to know the effects of insulin therapy on blood glucose, insulin and glucagon concentrations. Simulation results show that these different types of insulin have different effects on blood glucose concentration. Insulin therapy using lispro shows better blood glucose control after consumption of meals. Glargin gives better blood glucose control between meals and during sleep. Combination between lispro and glargine shows better glycemic control for whole day blood glucose level.

The glucagon test in the diagnosis of growth hormone deficiency in children with short stature younger than 6 years.

Science.gov (United States)

Secco, Andrea; di Iorgi, Natascia; Napoli, Flavia; Calandra, Erika; Ghezzi, Michele; Frassinetti, Costanza; Parodi, Stefano; Casini, Maria Rosaria; Lorini, Renata; Loche, Sandro; Maghnie, Mohamad

2009-11-01

Few studies have addressed the diagnostic role of the glucagon test in children with suspected GH deficiency (GHD). The objective of the study was to investigate the diagnostic value of the glucagon test as an alternative test to insulin tolerance test (ITT) and arginine in GHD children younger than 6 yr. This study was conducted in two pediatric endocrinology centers. Forty-eight children (median age 4.2 yr, median height -3.0 sd score) with GHD confirmed by a peak GH to ITT and arginine less than 10 microg/liter (median 4.7 and 3.4 microg/liter, respectively) underwent a glucagon stimulation test. Magnetic resonance imaging showed normal hypothalamic-pituitary anatomy in 24 children, isolated anterior pituitary hypoplasia in seven, and structural hypothalamic-pituitary abnormalities in 17. Median GH peak response to glucagon (13.5 microg/liter) was significantly higher than that observed after ITT and arginine (P short stature. Normative data for this test in young children need to be established before its use in clinical practice.

Nutrient-induced glucagon like peptide-1 release is modulated by serotonin

NARCIS (Netherlands)

Ripken, Dina; Wielen, van der Nikkie; Wortelboer, Heleen M.; Meijerink, Jocelijn; Witkamp, Renger F.; Hendriks, Henk F.J.

2016-01-01

Glucagon like peptide-1 (GLP-1) and serotonin are both involved in food intake regulation. GLP-1 release is stimulated upon nutrient interaction with G-protein coupled receptors by enteroendocrine cells (EEC), whereas serotonin is released from enterochromaffin cells (ECC). The central hypothesis

GLP-1/glucagon receptor co-agonism for treatment of obesity.

Science.gov (United States)

Sánchez-Garrido, Miguel A; Brandt, Sara J; Clemmensen, Christoffer; Müller, Timo D; DiMarchi, Richard D; Tschöp, Matthias H

2017-10-01

Over a relatively short period, obesity and type 2 diabetes have come to represent a large medical and economic burden to global societies. The epidemic rise in the prevalence of obesity has metabolic consequences and is paralleled by an increased occurrence of other diseases, such as diabetes, cancer and cardiovascular complications. Together, obesity and type 2 diabetes constitute one of the more preventable causes of premature death and the identification of novel, safe and effective anti-obesity drugs is of utmost importance. Pharmacological attempts to treat obesity have had limited success, with notable adverse effects, rendering bariatric surgery as the only current therapy for substantially improving body weight. Novel unimolecular, multifunctional peptides have emerged as one of the most promising medicinal approaches to enhance metabolic efficacy and restore normal body weight. In this review, we will mainly focus on the discovery and translational relevance of dual agonists that pharmacologically function at the receptors for glucagon and glucagon-like peptide-1. Such peptides have advanced to clinical evaluation and inspired the pursuit of multiple related approaches to achieving polypharmacy within single molecules.

Increased intracellular proteolysis reduces disease severity in an ER stress-associated dwarfism.

Science.gov (United States)

Mullan, Lorna A; Mularczyk, Ewa J; Kung, Louise H; Forouhan, Mitra; Wragg, Jordan Ma; Goodacre, Royston; Bateman, John F; Swanton, Eileithyia; Briggs, Michael D; Boot-Handford, Raymond P

2017-10-02

The short-limbed dwarfism metaphyseal chondrodysplasia type Schmid (MCDS) is linked to mutations in type X collagen, which increase ER stress by inducing misfolding of the mutant protein and subsequently disrupting hypertrophic chondrocyte differentiation. Here, we show that carbamazepine (CBZ), an autophagy-stimulating drug that is clinically approved for the treatment of seizures and bipolar disease, reduced the ER stress induced by 4 different MCDS-causing mutant forms of collagen X in human cell culture. Depending on the nature of the mutation, CBZ application stimulated proteolysis of misfolded collagen X by either autophagy or proteasomal degradation, thereby reducing intracellular accumulation of mutant collagen. In MCDS mice expressing the Col10a1.pN617K mutation, CBZ reduced the MCDS-associated expansion of the growth plate hypertrophic zone, attenuated enhanced expression of ER stress markers such as Bip and Atf4, increased bone growth, and reduced skeletal dysplasia. CBZ produced these beneficial effects by reducing the MCDS-associated abnormalities in hypertrophic chondrocyte differentiation. Stimulation of intracellular proteolysis using CBZ treatment may therefore be a clinically viable way of treating the ER stress-associated dwarfism MCDS.

Unprecedented high insulin secretion in a healthy human subject after intravenous glucagon-like peptide-1

DEFF Research Database (Denmark)

Knop, Filip K; Lund, Asger; Madsbad, Sten

2014-01-01

BACKGROUND: The gut-derived incretin hormones, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, are released in response to ingestion of nutrients. Both hormones are highly insulinotropic in strictly glucose-dependent fashions and glucagon-like peptide-1 is often referred...... to as one of the most insulinotropic substances known. CASE PRESENTATION: Plasma insulin and C-peptide concentrations were measured in a healthy Caucasian male (age: 53 years; body mass index: 28.6 kg/m2; fasting plasma glucose: 5.7 mM; 2 h plasma glucose value following 75 g-oral glucose tolerance test: 3...

Involvement of μ/m-calpain in the proteolysis and meat quality changes during postmortem storage of chicken breast muscle.

Science.gov (United States)

Zhao, Liang; Xing, Tong; Huang, Jichao; Qiao, Yan; Chen, Yulian; Huang, Ming

2018-02-01

The objective of this study was to investigate the role of calpain isotypes, especially poultry-specific μ/m-calpain in the proteolysis and meat quality changes of chicken breast muscle during postmortem storage. Calpain activity was detected by casein zymography, while the degradation of titin, desmin and Troponin-T was analyzed by sodium dodecyl sulfate - polyacrylamide gel electrophoresis and western blot. Meat quality indicators such as water holding capacity and tenderness were also studied. The correlation analysis between calpain activity, proteolysis and the changes in meat quality indicators indicated that there were strong correlations for μ-calpain during the first 12 h of storage, while such strong correlations for μ/m-calpain were only found in samples stored from 12 h to 7 days. Our study suggested that μ-calpain played a major role in meat quality changes while μ/m-calpain could also be involved but played a limited role in the proteolysis and meat quality changes during 12 h to 7 days postmortem storage of chicken breast muscle. © 2017 Japanese Society of Animal Science.

The use of in situ proteolysis in the crystallization of murine CstF-77

International Nuclear Information System (INIS)

Bai, Yun; Auperin, Thierry C.; Tong, Liang

2007-01-01

In situ proteolysis with fungal protease or subtilisin is crucial for the crystallization of murine CstF-77. The cleavage-stimulation factor (CstF) is required for the cleavage of the 3′-end of messenger RNA precursors in eukaryotes. During structure determination of the 77 kDa subunit of the murine CstF complex (CstF-77), it was serendipitously discovered that a solution infected by a fungus was crucial for the crystallization of this protein. CstF-77 was partially proteolyzed during crystallization; this was very likely to have been catalyzed by a protease secreted by the fungus. It was found that the fungal protease can be replaced by subtilisin and this in situ proteolysis protocol produced crystals of sufficient size for structural studies. After an extensive search, it was found that 55% glucose can be used as a cryoprotectant while maintaining the diffraction quality of the crystals; most other commonly used cryoprotectants were detrimental to the diffraction quality

Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning

DEFF Research Database (Denmark)

Thymann, Thomas; Le Huërou-Luron, I; Petersen, Y M

2014-01-01

Transition from sow’s milk to solid feed is associated with intestinal atrophy and diarrhea. We hypothesized that the intestinotrophic hormone glucagon-like peptide 2 (GLP-2) would induce a dose- and health status-dependent effect on gut adaptation. In Exp. 1, weaned pigs (average BW at weaning 4...

Effects of glucagon-like peptide-1 on endothelial function in type 2 diabetes patients with stable coronary artery disease

DEFF Research Database (Denmark)

Nyström, Thomas; Gutniak, Mark K; Zhang, Qimin

2004-01-01

GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus...... and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S......(I)) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S(I). Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial...

Cholinergic signaling mediates the effects of xenin-25 on secretion of pancreatic polypeptide but not insulin or glucagon in humans with impaired glucose tolerance.

Directory of Open Access Journals (Sweden)

Songyan Wang

Full Text Available We previously demonstrated that infusion of an intestinal peptide called xenin-25 (Xen amplifies the effects of glucose-dependent insulinotropic polypeptide (GIP on insulin secretion rates (ISRs and plasma glucagon levels in humans. However, these effects of Xen, but not GIP, were blunted in humans with type 2 diabetes. Thus, Xen rather than GIP signaling to islets fails early during development of type 2 diabetes. The current crossover study determines if cholinergic signaling relays the effects of Xen on insulin and glucagon release in humans as in mice. Fasted subjects with impaired glucose tolerance were studied. On eight separate occasions, each person underwent a single graded glucose infusion- two each with infusion of albumin, Xen, GIP, and GIP plus Xen. Each infusate was administered ± atropine. Heart rate and plasma glucose, insulin, C-peptide, glucagon, and pancreatic polypeptide (PP levels were measured. ISRs were calculated from C-peptide levels. All peptides profoundly increased PP responses. From 0 to 40 min, peptide(s infusions had little effect on plasma glucose concentrations. However, GIP, but not Xen, rapidly and transiently increased ISRs and glucagon levels. Both responses were further amplified when Xen was co-administered with GIP. From 40 to 240 min, glucose levels and ISRs continually increased while glucagon concentrations declined, regardless of infusate. Atropine increased resting heart rate and blocked all PP responses but did not affect ISRs or plasma glucagon levels during any of the peptide infusions. Thus, cholinergic signaling mediates the effects of Xen on insulin and glucagon release in mice but not humans.

Characterization of linear forms of the circular enterocin AS-48 obtained by limited proteolysis

NARCIS (Netherlands)

Montalbán-López, Manuel; Spolaore, Barbara; Pinato, Odra; Martínez-Bueno, Manuel; Valdivia, Eva; Maqueda, Mercedes; Fontana, Angelo

2008-01-01

AS-48 is a 70-residue circular peptide from Enterococcus faecalis with a broad antibacterial activity. Here, we produced by limited proteolysis a protein species carrying a single nicking and fragments of 55 and 38 residues. Nicked AS-48 showed a lower helicity by far-ultraviolet circular dichroism

The separate and combined impact of the intestinal hormones, GIP, GLP-1, and GLP-2, on glucagon secretion in type 2 diabetes

DEFF Research Database (Denmark)

Lund, Asger; Vilsbøll, Tina; Bagger, Jonatan I

2011-01-01

Type 2 diabetes mellitus (T2DM) is associated with reduced suppression of glucagon during oral glucose tolerance test (OGTT), whereas isoglycemic intravenous glucose infusion (IIGI) results in normal glucagon suppression in these patients. We examined the role of the intestinal hormones glucose...

Orlistat inhibition of intestinal lipase acutely increases appetite and attenuates postprandial glucagon-like peptide-1-(7-36)-amide-1, cholecystokinin, and peptide YY concentrations

DEFF Research Database (Denmark)

Ellrichmann, Mark; Kapelle, Mario; Ritter, Peter R

2008-01-01

of Orlistat or placebo. Gastric emptying, gallbladder volume and the plasma levels of CCK, PYY, GLP-1, and ghrelin were determined and appetite sensations were measured using visual analogue scales. RESULTS: Gastric emptying was accelerated by Orlistat administration (P emptying.......0001), whereas appetite and prospective food consumption increased (P gastric and gallbladder emptying and reduces...... whether Orlistat alters the secretion of glucagon-like peptide-1-(7-36)-amide (GLP-1), cholecystokinin (CCK), peptide YY (PYY), and ghrelin as well as postprandial appetite sensations. METHODS: Twenty-five healthy human volunteers were examined with a solid-liquid test meal after the oral administration...

Age-related changes in factor VII proteolysis in vivo.

Science.gov (United States)

Ofosu, F A; Craven, S; Dewar, L; Anvari, N; Andrew, M; Blajchman, M A

1996-08-01

Previous studies have reported that pre-operative plasmas of patients over the age of 40 years who developed post-operative deep vein thrombosis (DVT) had approximately twice the amount of proteolysed factor VII found in plasmas of patients in whom prophylaxis with heparin or low M(r) heparin was successful. These and other studies also reported higher concentrations of thrombin-antithrombin III in pre- and post-operative plasmas of patients who developed post-operative thrombosis than in plasmas of patients in whom prophylaxis was successful. Whether the extent of factor VII proteolysis seen in the patients who developed post-operative DVT is related to the severity of their disease or age is not known. This report investigated age-related changes in the concentrations of total factor VII protein, factor VII zymogen, factor VIIa, tissue factor pathway inhibitor, thrombin-antithrombin III, and prothrombin fragment 1 + 2 in normal plasmas and the relationships between these parameters. With the exception of thrombin-antithrombin III, statistically significant increases in the concentrations of these parameters with age were found. Additionally, the differences between the concentrations of total factor VII protein and factor VII zymogen, an index factor VII proteolysis in vivo, were statistically significant only for individuals over age 40. Using linear regression analysis, a significant correlation was found to exist between the concentrations of plasma factor VIIa and prothrombin fragment 1 + 2. Since factor VIIa-tissue factor probably initiates coagulation in vivo, we hypothesize that the elevated plasma factor VIIa (reflecting a less tightly regulated tissue factor activity and therefore increased thrombin production in vivo) accounts for the high risk for post-operative thrombosis seen in individuals over the age of 40.

Glucagon-like peptide-1, a new hormone of the entero-insular axis

DEFF Research Database (Denmark)

Orskov, C

1992-01-01

reported in Type 2 (noninsulin-dependent) diabetic patients, however, the consequences of the elevation are not yet known. However, elevated levels of glucagon-like peptide-1 in patients with increased gastric emptying rate (post-gastrectomy syndromes) may be responsible for the exaggerated insulin...

Glucagon-like peptide 1 receptor agonists: a new approach to type 2 ...

African Journals Online (AJOL)

Hypoglycaemia and weight gain that are associated with many antidiabetic medications may interfere with the implementation and long-term application of treatment strategies. Glucose homeostasis is dependent on a complex interplay of multiple hormones and gastrointestinal peptides, including glucagon-like peptide 1 ...

[Glucagon-like peptide 2, a neurotransmitter with a newly discovered role in the regulation of food ingestion].

Science.gov (United States)

Tang-Christensen, M; Larsen, P J; Thulesen, J; Nielsen, J R; Vrang, N

2001-01-15

We report here that glucagon-like peptide 2(GLP-2) and its receptor constitute a distinct projection system connecting the nucleus of the solitary tract with the dorsomedial hypothalamic nucleus (DMH). The DMH contains a dense plexus of GLP-2 immunoreactive fibres and is the only hypothalamic nucleus expressing GLP-2 receptor mRNA. Consistent with this, central application of GLP-2 activates the expression of neurones solely in the DMH. Furthermore, central administration of GLP-2 causes a dose-related, a pharmacologically and behaviourally specific inhibition of food intake in rats. Surprisingly, the alleged GLP-1 receptor antagonist, Exending (9-39), proved a functional antagonist of centrally applied GLP-2. These data implicate GLP-2 as an important neurotransmitter in the regulation of food intake and likely bodyweight. Our data therefore point to the DMH as a crossroad for endocrine and visceral information affecting feeding behaviour.

Pharmacokinetics and pharmacodynamics of various glucagon dosages at different blood glucose levels

NARCIS (Netherlands)

Blauw, H.; Wendl, I.; DeVries, J. H.; Heise, T.; Jax, T.

2016-01-01

To evaluate the pharmacokinetics and pharmacodynamics of different doses of glucagon administered subcutaneously (s.c.) at different blood glucose levels. This study was an open-label, randomized, three-period, cross-over experiment in 6 patients with type 1 diabetes. During each of the three

Use of high-gradient magnetic fishing for reducing proteolysis during fermentation

DEFF Research Database (Denmark)

Maury, Trine Lütken; Ottow, Kim Ekelund; Brask, Jesper

2012-01-01

Proteolysis during fermentation may have a severe impact on the yield and quality of a secreted product. In the current study, we demonstrate the use of high-gradient magnetic fishing (HGMF) as an efficient alternative to the more conventional methods of preventing proteolytic degradation....... Bacitracin-linked magnetic affinity adsorbents were employed directly in a fermenter during Bacillus licheniformis cultivation to remove trace amounts of unwanted proteases. The constructed magnetic adsorbents had excellent, highly specific binding characteristics in the fermentation broth (K(d) = 1...

Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism.

Science.gov (United States)

Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob; Kassem, Moustapha; Frost, Morten

2018-01-01

The relationship between gut and skeleton is increasingly recognized as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibit several physiological functions including regulation of islet hormone secretion and glucose levels. A number of GLP-1 receptor agonists (GLP-1RAs) are currently used in treatment of type 2 diabetes and obesity. However, GIP and GLP-1 cognate receptors are widely expressed suggesting that incretin hormones mediate effects beyond control of glucose homeostasis, and reports on associations between incretin hormones and bone metabolism have emerged. The aim of this MiniReview was to provide an overview of current knowledge regarding the in vivo and in vitro effects of GIP and GLP-1 on bone metabolism. We identified a total of 30 pre-clinical and clinical investigations of the effects of GIP, GLP-1 and GLP-1RAs on bone turnover markers, bone mineral density (BMD), bone microarchitecture and fracture risk. Studies conducted in cell cultures and rodents demonstrated that GIP and GLP-1 play a role in regulating skeletal homeostasis, with pre-clinical data suggesting that GIP inhibits bone resorption whereas GLP-1 may promote bone formation and enhance bone material properties. These effects are not corroborated by clinical studies. While there is evidence of effects of GIP and GLP-1 on bone metabolism in pre-clinical investigations, clinical trials are needed to clarify whether similar effects are present and clinically relevant in humans. © 2017 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Oleic acid stimulates glucagon-like peptide-1 release from enteroendocrine cells by modulating cell respiration and glycolysis.

Science.gov (United States)

Clara, Rosmarie; Langhans, Wolfgang; Mansouri, Abdelhak

2016-03-01

Glucagon-like peptide-1 (GLP-1) is a potent satiating and incretin hormone released by enteroendocrine L-cells in response to eating. Dietary fat, in particular monounsaturated fatty acids, such as oleic acid (OA), potently stimulates GLP-1 secretion from L-cells. It is, however, unclear whether the intracellular metabolic handling of OA is involved in this effect. First we determined the optimal medium for the bioenergetics measurements. Then we examined the effect of OA on the metabolism of the immortalized enteroendocrine GLUTag cell model and assessed GLP-1 release in parallel. We measured oxygen consumption rate and extracellular acidification rate in response to OA and to different metabolic inhibitors with the Seahorse extracellular flux analyzer. OA increased cellular respiration and potently stimulated GLP-1 release. The fatty acid oxidation inhibitor etomoxir did neither reduce OA-induced respiration nor affect the OA-induced GLP-1 release. In contrast, inhibition of the respiratory chain or of downstream steps of aerobic glycolysis reduced the OA-induced GLP-1 release, and an inhibition of the first step of glycolysis by addition of 2-deoxy-d-glucose even abolished it. These findings indicate that an indirect stimulation of glycolysis is crucial for the OA-induced release of GLP-1. Copyright © 2015 Elsevier Inc. All rights reserved.

[Pharmacological mechanism analysis of oligopeptide from Pinctada fucata based on in silico proteolysis and protein interaction network].

Science.gov (United States)

Chen, Yan-Kun; Qiao, Lian-Sheng; Huo, Xiao-Qian; Zhang, Xu; Han, Na; Zhang, Yan-Ling

2017-09-01

Pinctada fucata oligopeptide is one of key pharmaceutical effective constituents of P. fucata. It is significant to analyze its pharmacological effect and mechanism. This study aims to discover the potential oligopeptides from P. fucata and analyze the mechanism of P. fucata oligopeptide based on in silico technologies and protein interaction network(PIN). First, main protein sequences of P. fucata were collected, and oligopeptides were obtained using in silico gastrointestinal tract proteolysis. Then, key potential targets of P. fucata oligopeptides were obtained through pharmacophore screening. The protein-protein interaction(PPI) of targets was achieved and implemented to construct PIN and analyze the mechanism of P. fucata oligopeptides. P. fucata oligopeptide database was constructed based on in silico technologies, including 458 oligopeptides. Twelve modules were identified from PIN by a graph theoretic clustering algorithm Molecular Complex Detection(MCODE) and analyzed by Gene ontology(GO) enrichment. The results indicated that P. fucata oligopeptides have an effect in treating neurological diseases, such as Alzheimer's disease. In silico proteolysis could be used to analyze the protein sequences of traditional Chinese medicine(TCM). According to the combination of in silico proteolysis and PIN, the biological activity of oligopeptides could be interpreted rapidly based on the known TCM protein sequence. The study provides the methodology basis for rapidly and efficiently implementing the mechanism analysis of TCM oligopeptides. Copyright© by the Chinese Pharmaceutical Association.

Glucagon-like peptide-2 inhibits antral emptying in man, but is not as potent as glucagon-like peptide-1

DEFF Research Database (Denmark)

Nagell, C F; Wettergren, A; Pedersen, J F

2004-01-01

with GLP-1 inhibits gastric emptying and the sensation of hunger in man. METHODS: Eight healthy volunteers were tested in a double-blind, placebo-controlled fashion. Antral emptying of a liquid meal and hunger ratings were determined using ultrasound technology and visual analogue scales scoring during...... infusions of saline, GLP-2 (0.5, and 1.0 pmol kg body wt(-1) min(-1)), GLP-1 (0.5 pmol kg body wt(-1) min(-1)) or GLP-1 and GLP-2 (0.5 pmol kg body wt(-1) min(-1)). RESULTS: The GLP-2 infusions resulted in a dose-dependent increase in antral emptying time (35%; ns and 75%; P = 0.049) compared to saline...

Glucagon like peptide-1-induced glucose metabolism in differentiated human muscle satellite cells is attenuated by hyperglycemia

DEFF Research Database (Denmark)

Green, Charlotte J; Henriksen, Tora I; Pedersen, Bente K

2012-01-01

Glucagon like peptide-1 (GLP-1) stimulates insulin secretion from the pancreas but also has extra-pancreatic effects. GLP-1 may stimulate glucose uptake in cultured muscle cells but the mechanism is not clearly defined. Furthermore, while the pancreatic effects of GLP-1 are glucose-dependent, the......Glucagon like peptide-1 (GLP-1) stimulates insulin secretion from the pancreas but also has extra-pancreatic effects. GLP-1 may stimulate glucose uptake in cultured muscle cells but the mechanism is not clearly defined. Furthermore, while the pancreatic effects of GLP-1 are glucose...

Overexpression of the essential Sis1 chaperone reduces TDP-43 effects on toxicity and proteolysis

Science.gov (United States)

Park, Sei-Kyoung; Hong, Joo Y.; Arslan, Fatih; Tietsort, Alex; Tank, Elizabeth M. H.; Li, Xingli

2017-01-01

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by selective loss of motor neurons with inclusions frequently containing the RNA/DNA binding protein TDP-43. Using a yeast model of ALS exhibiting TDP-43 dependent toxicity, we now show that TDP-43 overexpression dramatically alters cell shape and reduces ubiquitin dependent proteolysis of a reporter construct. Furthermore, we show that an excess of the Hsp40 chaperone, Sis1, reduced TDP-43’s effect on toxicity, cell shape and proteolysis. The strength of these effects was influenced by the presence of the endogenous yeast prion, [PIN+]. Although overexpression of Sis1 altered the TDP-43 aggregation pattern, we did not detect physical association of Sis1 with TDP-43, suggesting the possibility of indirect effects on TDP-43 aggregation. Furthermore, overexpression of the mammalian Sis1 homologue, DNAJB1, relieves TDP-43 mediated toxicity in primary rodent cortical neurons, suggesting that Sis1 and its homologues may have neuroprotective effects in ALS. PMID:28531192

Negative Energy Balance Blocks Neural and Behavioral Responses to Acute Stress by "Silencing" Central Glucagon-Like Peptide 1 Signaling in Rats.

Science.gov (United States)

Maniscalco, James W; Zheng, Huiyuan; Gordon, Patrick J; Rinaman, Linda

2015-07-29

acute stress to activate hindbrain neurons that are immunoreactive for either prolactin-releasing peptide or glucagon-like peptide 1, and attenuates the activation of their stress-sensitive projection targets in the limbic forebrain. In nonfasted rats, central antagonism of glucagon-like peptide 1 receptors partially mimics the effect of an overnight fast by blocking the ability of acute stress to inhibit food intake, and by attenuating stress-induced activation of hindbrain and limbic forebrain neurons. We propose that caloric restriction attenuates behavioral and physiological responses to acute stress by "silencing" central glucagon-like peptide 1 signaling pathways. Copyright © 2015 the authors 0270-6474/15/3510701-14$15.00/0.

The ATPase and protease domains of yeast mitochondrial Lon : Roles in proteolysis and respiration-dependent growth

NARCIS (Netherlands)

van Dijl, JM; Kutejova, E; Suda, K; Perecko, D; Schatz, G; Suzuki, CK

1998-01-01

The ATP-dependent Lon protease of Saccharomyces cerevisiae mitochondria is required for selective proteolysis in the matrix, maintenance of mitochondrial DNA, and respiration-dependent growth. Lon may also possess a chaperone-like function that facilitates protein degradation and protein-complex

Proteolysis inside the membrane is a rate-governed reaction not driven by substrate affinity.

Science.gov (United States)

Dickey, Seth W; Baker, Rosanna P; Cho, Sangwoo; Urban, Siniša

2013-12-05

Enzymatic cleavage of transmembrane anchors to release proteins from the membrane controls diverse signaling pathways and is implicated in more than a dozen diseases. How catalysis works within the viscous, water-excluding, two-dimensional membrane is unknown. We developed an inducible reconstitution system to interrogate rhomboid proteolysis quantitatively within the membrane in real time. Remarkably, rhomboid proteases displayed no physiological affinity for substrates (K(d) ~190 μM/0.1 mol%). Instead, ~10,000-fold differences in proteolytic efficiency with substrate mutants and diverse rhomboid proteases were reflected in k(cat) values alone. Analysis of gate-open mutant and solvent isotope effects revealed that substrate gating, not hydrolysis, is rate limiting. Ultimately, a single proteolytic event within the membrane normally takes minutes. Rhomboid intramembrane proteolysis is thus a slow, kinetically controlled reaction not driven by transmembrane protein-protein affinity. These properties are unlike those of other studied proteases or membrane proteins but are strikingly reminiscent of one subset of DNA-repair enzymes, raising important mechanistic and drug-design implications. Copyright © 2013 Elsevier Inc. All rights reserved.

Localization of glucagon and insulin cells and its variation with respect to physiological events in Eutropis carinata

OpenAIRE

Vidya. R. Chandavar; Prakash. R. Naik

2011-01-01

The aim of the present investigation was to localize glucagon and insulin immunoreactive (IR) cells of pancreas during annual seasonal cycle of reproduction and to find out whether they had any effect on the regulation of plasma glucose level in the skink Eutropis carinata. Immunolocalized pancreatic cells revealed significantly different mean numbers in different periods of reproduction. The numbers of glucagon-IR and insulin-IR cells were highest in recrudescent period which was corresponde...

Additive effects of glucagon-like peptide 1 and pioglitazone in patients with type 2 diabetes

DEFF Research Database (Denmark)

Zander, Mette; Christiansen, Allan; Madsbad, Sten

2004-01-01

plasma levels of glucose, insulin, glucagon, free fatty acids (FFAs), and sensation of appetite. RESULTS: Fasting plasma glucose decreased from 13.5 +/- 1.2 mmol/l (saline) to 11.7 +/- 1.2 (GLP-1) and 11.5 +/- 1.2 (pioglitazone) and further decreased to 9.9 +/- 1.0 (combination) (P ...-hour mean plasma glucose levels were reduced from 13.7 +/- 1.1 mmol/l (saline) to 10.6 +/- 1.0 (GLP-1) and 12.0 +/- 1.2 (pioglitazone) and were further reduced to 9.5 +/- 0.8 (combination) (P ....01). Glucagon levels were reduced in GLP-1 and combination therapy compared with saline and monotherapy with pioglitazone (P Sensation of appetite was reduced during monotherapy...

Plasma levels of glucagon like peptide-1 associate with diastolic function in elderly men

DEFF Research Database (Denmark)

Nathanson, D; Zethelius, B; Berne, C

2011-01-01

Congestive heart failure is a major cause of morbidity and mortality in diabetes. Besides the glycaemic effects of glucagon-like peptide 1 (GLP-1) mimetics, their effects on the heart are of interest....

Study on the inter-relationship among the changes of serum levels of leptin, insulin and glucagon in patients with DM2 complicated with hypertension

International Nuclear Information System (INIS)

Zeng Zhiwei; Yan Songqin; Tan Wei

2006-01-01

Objective: To investigate the inter-relationship among the changes of serum leptin, insulin and glucagon levels in patients with type 2 diabetes mellitus (DM2) complicated with hypertension. Methods: Serum leptin, insulin and glucagon levels were, measured with RIA in 30 DM2 patients complicated with hypertension, 30 DM2 patients without hypertension and 30 controls. Results: Serum levels of leptin, insulin and glucagon in all the DM2 patients were significantly higher than those in controls (P<0.01). In addition, the serum levels in DM2 patients with hypertension were significantly higher than those in DM2 patients without hypertension (P<0.05). These levels were positively correlated with the severity of hypertension. Conclusion: The role played by leptin and glucagon in the pathogenesis of type 2 diabetes mellitns should be furthur studied. (authors)

Oligomerization of a Glucagon-like Peptide 1 Analog: Bridging Experiment and Simulations

DEFF Research Database (Denmark)

Frederiksen, Tine Maja; Sønderby, Pernille; Ryberg, Line A.

2015-01-01

The glucagon-like peptide 1 (GLP-1) analog, liraglutide, is a GLP-1 agonist and is used in the treatment of type-2 diabetes mellitus and obesity. From a pharmaceutical perspective, it is important to know the oligomerization state of liraglutide with respect to stability. Compared to GLP-1...

Incorporation of Allium sativum in yogurt: In vitro study on inhibition of diabetes- and hypertension-associated enzymes

Directory of Open Access Journals (Sweden)

Shabboo Amirdivani Amirdivani

2015-06-01

Full Text Available The effects of inclusion of Allium sativum on yogurt formation and subsequent storage (4°C, up to 28 days on proteolysis, microbial activity, the inhibition of a-amylase, a-glucosidase and angiotensin-1 converting enzyme (ACE-1 in vitro were investigated. A. sativum-yogurt showed higher rates of pH reduction and increment of TA than plain-yogurt during incubation at 41°C. Highest proteolysis,  on day 7 showed in A. sativum-yogurt (62.7±0.80 mg/mL, which was 2-flod higher than plain yogurt (31.0±0.96 mg/mL. Bacterial counts in A.sativum-yogurt were higher for Lactobacillus spp. but lower for S. thermophillus (p<0.05 compared to those in plain yogurt throughout refrigerated storage. Highest inhibitory activities for α-amylase were recorded on day 14 of storage for A. sativum- and plain-yogurts (IC50= 13.7±1.99and 26.3±2.15mg respectively; p<0.05 and on day 7 for α-glucosidase (IC50= 120.7±22.71 and 192.3±33.24mg respectively; p<0.05. The highest anti-ACE-I activity was observed on day 7 of refrigerated storage with A. sativum-yogurt (IC50=6.9±0.23mg being more potent than plain-yogurt (IC50=9.7±0.12mg; p<0.05. A. sativum-yogurt was not favoured for overall aroma, sourness and bitterness in the sensory evaluations but recorded the same overall preference as plain yogurt. A. sativum enhanced the fermentation of yogurt in favour of the population of Lactobacillus spp, stimulated proteolysis of milk proteins and increased the in vitro inhibition of key enzymes associated with diabetes and hypertension.

Paralog-divergent Features May Help Reduce Off-target Effects of Drugs: Hints from Glucagon Subfamily Analysis

Directory of Open Access Journals (Sweden)

Zhining Sa

2017-08-01

Full Text Available Side effects from targeted drugs remain a serious concern. One reason is the nonselective binding of a drug to unintended proteins such as its paralogs, which are highly homologous in sequences and have similar structures and drug-binding pockets. To identify targetable differences between paralogs, we analyzed two types (type-I and type-II of functional divergence between two paralogs in the known target protein receptor family G-protein coupled receptors (GPCRs at the amino acid level. Paralogous protein receptors in glucagon-like subfamily, glucagon receptor (GCGR and glucagon-like peptide-1 receptor (GLP-1R, exhibit divergence in ligands and are clinically validated drug targets for type 2 diabetes. Our data showed that type-II amino acids were significantly enriched in the binding sites of antagonist MK-0893 to GCGR, which had a radical shift in physicochemical properties between GCGR and GLP-1R. We also examined the role of type-I amino acids between GCGR and GLP-1R. The divergent features between GCGR and GLP-1R paralogs may be helpful in their discrimination, thus enabling the identification of binding sites to reduce undesirable side effects and increase the target specificity of drugs.

A longitudinal study of plasma insulin and glucagon in women with previous gestational diabetes

DEFF Research Database (Denmark)

Damm, P; Kühl, C; Hornnes, P

1995-01-01

OBJECTIVE: To investigate whether plasma insulin or glucagon predicts later development of diabetes in women with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: The subjects studied were 91 women with diet-treated GDM and 33 healthy women. Plasma insulin and glucagon during a 50...... at follow-up (2 had insulin-dependent diabetes mellitus, 13 had non-insulin-dependent diabetes mellitus, and 12 had impaired glucose tolerance). Compared with the control subjects, women with previous GDM had relatively impaired insulin secretion (decreased insulinogenic index and delayed peak insulin...... for subsequent development of overt diabetes (logistic regression analysis). CONCLUSIONS: Women who develop GDM have a relative insulin secretion deficiency, the severity of which is predictive for later development of diabetes. Furthermore, our data indicate that their relatively reduced beta-cell function may...

Relationship between Optimum Mini-doses of Glucagon and Insulin Levels when Treating Mild Hypoglycaemia in Patients with Type 1 Diabetes - A Simulation Study

DEFF Research Database (Denmark)

Ranjan, Ajenthen; Wendt, Sabrina Lyngbye; Schmidt, Signe

2017-01-01

-treated type 1 diabetes. In each simulation, one of ten different and individualized subcutaneous insulin boluses was administered to decrease plasma glucose (PG) from 7.0 to ≤3.9 mmol/l. Insulin levels were estimated as ratio of actual to baseline serum insulin concentration (se/ba-insulin), insulin on board...... (IOB) or percentage of IOB to total daily insulin dose (IOB/TDD). Insulin bolus sizes were chosen to provide pre-defined insulin levels when PG reached 3.9 mmol/l, where one of 17 subcutaneous glucagon boluses was administered. Optimum glucagon bolus to treat mild hypoglycaemia at varying insulin...... levels was the lowest dose that in most patients caused PG peak between 5.0 and 10.0 mmol/l and sustained PG ≥ 3.9 mmol/l for 2 hr after the bolus. PG response to glucagon declined with increasing insulin levels. The glucagon dose to optimally treat mild hypoglycaemia depended exponentially on insulin...

Lak of influence of glucagon on glucose homeostasis after prolonged exercise in rats

DEFF Research Database (Denmark)

Galbo, H; Richter, Erik; Holst, J J

1977-01-01

The significance of glucagon for post-exercise glucose homeostasis has been studied in rats fasted overnight. Immediately after exhaustive swimming either rabbit-antiglucagon serum or normal rabbit serum was injected by cardiac puncture. Cardiac blood and samples of liver and muscle tissue were...

Chemical Hybridization of Glucagon and Thyroid Hormone Optimizes Therapeutic Impact for Metabolic Disease

DEFF Research Database (Denmark)

Finan, Brian; Clemmensen, Christoffer; Zhu, Zhimeng

2016-01-01

Glucagon and thyroid hormone (T3) exhibit therapeutic potential for metabolic disease but also exhibit undesired effects. We achieved synergistic effects of these two hormones and mitigation of their adverse effects by engineering chemical conjugates enabling delivery of both activities within on...

Continuous fast Fourier transforms cyclic voltammetry as a new approach for investigation of skim milk k-casein proteolysis, a comparative study.

Science.gov (United States)

Shayeh, Javad Shabani; Sefidbakht, Yahya; Siadat, Seyed Omid Ranaei; Niknam, Kaveh

2017-10-01

Cheese production is relied upon the action of Rennet on the casein micelles of milk. Chymosin assay methods are usually time consuming and offline. Herein, we report a new electrochemical technique for studying the proteolysis of K-casein. The interaction of rennet and its substrate was studied by fast Fourier transform continuous cyclic voltammetry (FFTCCV) based on a determination of k-casein in aqueous solution. FFTCCV technique is a very useful method for studying the enzymatic procedures. Fast response, no need of modified electrodes or complex equipment is some of FFTCCV advantages. Various concentrations of enzyme and substrate were selected and the increase in the appearance of charged species in solution as a result of the addition of rennet was studied. Data obtained using FFTCCV technique were also confirmed by turbidity analysis. The results show that rennet proteolysis activity occurs in much shorter time scales compare with its aggregation. Hence, following the appearance of charged segments as a result of proteolysis could be under consideration as a rapid and online method. Copyright © 2017 Elsevier B.V. All rights reserved.

Early phase glucagon and insulin secretory abnormalities, but not incretin secretion, are similarly responsible for hyperglycemia after ingestion of nutrients

DEFF Research Database (Denmark)

Yabe, Daisuke; Kuroe, Akira; Watanabe, Koin

2015-01-01

AIMS: Hypersecretion of glucagon and reduced insulin secretion both contribute to hyperglycemia in type 2 diabetes (T2DM). However, the relative contributions of impaired glucagon and insulin secretions in glucose excursions at the various stages of T2DM development remain to be determined. METHODS...... secretions but not incretin secretion are involved in hyperglycemia after ingestion of nutrients in T2DM of even a short duration....

Fixed ratio combinations of glucagon like peptide 1 receptor agonists with basal insulin: a systematic review and meta-analysis.

Science.gov (United States)

Liakopoulou, Paraskevi; Liakos, Aris; Vasilakou, Despoina; Athanasiadou, Eleni; Bekiari, Eleni; Kazakos, Kyriakos; Tsapas, Apostolos

2017-06-01

Basal insulin controls primarily fasting plasma glucose but causes hypoglycaemia and weight gain, whilst glucagon like peptide 1 receptor agonists induce weight loss without increasing risk for hypoglycaemia. We conducted a systematic review and meta-analysis of randomised controlled trials to investigate the efficacy and safety of fixed ratio combinations of basal insulin with glucagon like peptide 1 receptor agonists. We searched Medline, Embase, and the Cochrane Library as well as conference abstracts up to December 2016. We assessed change in haemoglobin A 1c , body weight, and incidence of hypoglycaemia and gastrointestinal adverse events. We included eight studies with 5732 participants in the systematic review. Switch from basal insulin to fixed ratio combinations with a glucagon like peptide 1 receptor agonist was associated with 0.72% reduction in haemoglobin A 1c [95% confidence interval -1.03 to -0.41; I 2  = 93%] and 2.35 kg reduction in body weight (95% confidence interval -3.52 to -1.19; I 2  = 93%), reducing also risk for hypoglycaemia [odds ratio 0.70; 95% confidence interval 0.57 to 0.86; I 2  = 85%] but increasing incidence of nausea (odds ratio 6.89; 95% confidence interval 3.73-12.74; I 2  = 79%). Similarly, switching patients from treatment with a glucagon like peptide 1 receptor agonist to a fixed ratio combination with basal insulin was associated with 0.94% reduction in haemoglobin A 1c (95% confidence interval -1.11 to -0.77) and an increase in body weight by 2.89 kg (95% confidence interval 2.17-3.61). Fixed ratio combinations of basal insulin with glucagon like peptide 1 receptor agonists improve glycaemic control whilst balancing out risk for hypoglycaemia and gastrointestinal side effects.

Glucagon-like peptide-1 receptor agonists for the treatment of type 2 diabetes

DEFF Research Database (Denmark)

Lund, Asger; Knop, Filip K; Vilsbøll, Tina

2014-01-01

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone, secreted in response to ingestion of nutrients, and has important effects on several of the pathophysiological features of type 2 diabetes (T2D). The effects include potentiation of insulin secretion, suppression of glucagon secretion...... effects. This review gives an overview of the clinical data on GLP-1R agonists that have been compared in head-to-head studies and focuses on relevant differences between the compounds. Highlighting these similarities and differences could be beneficial for physicians in choosing the best treatment......, slowing of gastric emptying and suppression of appetite. In circulation, GLP-1 has a half-life of approximately 2min due to rapid degradation by the enzyme dipeptidyl peptidase 4 (DPP-4). Because of this short half-life GLP-1 receptor (GLP-1R) agonists, resistant to degradation by DPP-4 have been...

Short-term glucagon stimulation test of C-peptide effect on glucose utilization in patients with type 1 diabetes mellitus.

Science.gov (United States)

Mojto, Viliam; Rausova, Zuzana; Chrenova, Jana; Dedik, Ladislav

2015-12-01

This work aimed to evaluate the use of a four-point glucagon stimulation test of C-peptide effect on glucose utilization in type 1 diabetic patients using a new mathematical model. A group of 32 type 1 diabetic patients and a group of 10 healthy control subjects underwent a four-point glucagon stimulation test with blood sampling at 0, 6, 15 and 30 min after 1 mg glucagon bolus intravenous administration. Pharmacokinetic and pharmacokinetic/pharmacodynamic models of C-peptide effect on glucose utilization versus area under curve (AUC) were used. A two-sample t test and ANOVA with Bonferroni correction were used to test the significance of differences between parameters. A significant difference between control and patient groups regarding the coefficient of whole-body glucose utilization and AUC C-peptide/AUC glucose ratio (p ≪ 0.001 and p = 0.002, respectively) was observed. The high correlation (r = 0.97) between modeled coefficient of whole-body glucose utilization and numerically calculated AUC C-peptide/AUC glucose ratio related to entire cohort indicated the stability of used method. The short-term four-point glucagon stimulation test allows the numerically calculated AUC C-peptide/AUC glucose ratio and/or the coefficient of whole-body glucose utilization calculated from model to be used to diagnostically identify type 1 diabetic patients.

Bile acids induce glucagon-like peptide 2 secretion with limited effects on intestinal adaptation in early weaned pigs

DEFF Research Database (Denmark)

Ipharraguerre, Ignacio R; Tedó, Gemma; Menoyo, David

2013-01-01

Early weaning is a stressful event characterized by a transient period of intestinal atrophy that may be mediated by reduced secretion of glucagon-like peptide (GLP) 2. We tested whether enterally fed bile acids or plant sterols could increase nutrient-dependent GLP-2 secretion and improve.......05) but did not affect plasma GLP-1 and feed intake. The intestinal expression of glucagon-like peptide 2 receptor, sodium-dependent bile acid transporter, farnesoid X receptor, and guanosine protein-coupled bile acid receptor genes were not affected by CDC treatment. The intragastric administration of CDC...

Secretion of glucagon-like peptide-1 in patients with type 2 diabetes mellitus

DEFF Research Database (Denmark)

Calanna, S; Christensen, M; Holst, Jens Juul

2013-01-01

We carried out a systematic review of clinical studies investigating glucagon-like peptide-1 (GLP-1) secretion in patients with type 2 diabetes and non-diabetic controls and performed meta-analyses of plasma total GLP-1 concentrations during an OGTT and/or meal test....

Glucagon and insulin response to meals in non-obese and obese Dutch women

NARCIS (Netherlands)

Hill, P.; Garbaczewski, L.; Koppeschaar, H.; Thijssen, J.H.H.; Waard, F. de

1987-01-01

Many digestive complaints are associated with abnormalities in gastrointestinal peptide hormone function. To investigate the effect of obesity on the release of pancreatic peptide hormones, we have compared the release of insulin and glucagon in non-obese-obese Dutch women in response to isocaloric

Chloroquine inhibits accessory cell presentation of soluble natural and synthetic protein antigens

DEFF Research Database (Denmark)

Buus, S; Werdelin, O

1984-01-01

We have studied the in vitro effect of the lysosomotrophic agent, chloroquine, on the presentation of soluble protein antigens by guinea pig accessory cells. Chloroquine inhibited the capacity of antigen-pulsed accessory cells to stimulate proliferation in appropriately primed T cells. The effect...... was time- and dose-dependent. A brief treatment solely of the accessory cells with the drug compromised their ability to stimulate primed T cells in a subsequent culture provided the accessory cells were treated with chloroquine before their exposure to the antigen. These results suggest that chloroquine...... acts on an early event in the antigen handling by accessory cells. Chloroquine is a well known inhibitor of lysosomal proteolysis, and it is likely that its effect on antigen presentation is caused by an inhibition of antigen degradation....

L-lysine escinat, thiotriazolin, gordox and mydocalm influence on oxygen tension in the intestinal wall and acid-base balance and limited proteolysis in intestinal venous blood in terms of intraabdominal hypertension modeling

Directory of Open Access Journals (Sweden)

Sapegin V.I.

2014-11-01

Full Text Available In acute experiments on rabbits there were studied changes in oxygen tension in the intestinal wall tissues, acid-base balance and limited proteolysis and its inhibitors in intestinal venous blood, protective action of L-lysine escinat (0,15 mg/kg / single dose, thiotriazolin (25 mg/kg / single dose, aprotinin (gordox (10,000 units/kg / single dose in sequential modeling of standard levels increasing of intra-abdominal hypertension (IAH — 50, 100, 150, 200, 250, 300, 350 m H2O, and also of tolperison (mydocalm (5 mg/kg / single dose on modeling of stable 3-hour IAH 200 m H2O. The IAH modeling was performed by means of stand of our construction. Under the influence of IAH the compensated metabolic acidosis in intestinal venous blood with a compensative hyperpnoe develops, decline of oxygen tension in tissues and activating of a limited proteolysis as well as decline of its inhibitors activity in intestinal venous blood occur. By the degree of metabolic acidosis prevention investigational preparations were distributed as follows gordox > thiotriazolin = L-lysine escinat = mydocalm, and by prevention of decline of oxygen tension in tissues — thiotriazolin > L-lysine escinat > mydocalm > gordox, it is is connected with different rate of methabolic products excretion into the blood, due to the influence on blood circulation and transcapilary exchange. By the degree of prevention of proteolytic activity and inhibitory potential changes, investigational preparations were distributed as follows: gordox > mydocalm > thiotriazolin > L-lysine escinat, this is connected with inhibition of proteolysis in gordox, and in other ones – with reduction of ischemic damage of tissues. Owing to different mechanism of action thiotriazolin, L-lysine escinat and mydocalm may be simultaneously recommended for a conservative treatment of patients with intraabdominal hypertension syndrome.

Protein- and diabetes-induced glomerular hyperfiltration: role of glucagon, vasopressin, and urea.

Science.gov (United States)

Bankir, Lise; Roussel, Ronan; Bouby, Nadine

2015-07-01

A single protein-rich meal (or an infusion of amino acids) is known to increase the glomerular filtration rate (GFR) for a few hours, a phenomenon known as "hyperfiltration." It is important to understand the factors that initiate this upregulation because it becomes maladaptive in the long term. Several mediators and paracrine factors have been shown to participate in this upregulation, but they are not directly triggered by protein intake. Here, we explain how a rise in glucagon and in vasopressin secretion, directly induced by protein ingestion, might be the initial factors triggering the hepatic and renal events leading to an increase in the GFR. Their effects include metabolic actions in the liver and stimulation of sodium chloride reabsorption in the thick ascending limb. Glucagon is not only a glucoregulatory hormone. It is also important for the excretion of nitrogen end products by stimulating both urea synthesis in the liver (along with gluconeogenesis from amino acids) and urea excretion by the kidney. Vasopressin allows the concentration of nitrogenous end products (urea, ammonia, etc.) and other protein-associated wastes in a hyperosmotic urine, thus allowing a very significant water economy characteristic of all terrestrial mammals. No hyperfiltration occurs in the absence of one or the other hormone. Experimental results suggest that the combined actions of these two hormones, along with the complex intrarenal handling of urea, lead to alter the composition of the tubular fluid at the macula densa and to reduce the intensity of the signal activating the tubuloglomerular feedback control of GFR, thus allowing GFR to raise. Altogether, glucagon, vasopressin, and urea contribute to set up the best compromise between efficient urea excretion and water economy. Copyright © 2015 the American Physiological Society.

Effects of chronic glucagon-like peptide-2 therapy during weaning in neonatal pigs

DEFF Research Database (Denmark)

Sigalet, David L; de Heuvel, Elaine; Wallace, Laurie

2014-01-01

BACKGROUND: The enteroendocrine hormone glucagon like peptide-2 (GLP-2) and its ligands are under development as therapeutic agents for a variety of intestinal pathologies. A number of these conditions occur in neonates and infants, and thus a detailed understanding of the effects of GLP-2 during...

Effects of proteolysis on the adenosinetriphosphatase activities of thymus myosin

International Nuclear Information System (INIS)

Vu, N.D.; Wagner, P.D.

1987-01-01

Limited proteolysis was used to identify regions on the heavy chains of calf thymus myosin which may be involved in ATP and actin binding. Assignments of the various proteolytic fragments to different parts of the myosin heavy chain were based on solubility, gel filtration, electron microscopy, and binding of 32 P-labeled regulatory light chains. Chymotrypsin rapidly cleaved within the head of thymus myosin to give a 70,000-dalton N-terminal fragment and a 140,000-dalton C-terminal fragment. These two fragments did not dissociate under nondenaturing conditions. Cleavage within the myosin tail to give heavy meromyosin occurred more slowly. Cleavage at the site 70,000 daltons from the N-terminus of the heavy chain caused about a 30-fold decrease in the actin concentration required to achieve half-maximal stimulation of the magnesium-adenosinetriphosphatase (Mg-ATPase) activity of unphosphorylated thymus myosin. The actin-activated ATPase activity of this digested myosin was only slightly affected by light chain phosphorylation. Actin inhibited the cleavage at this site by chymotrypsin. In the presence of ATP, chymotrypsin rapidly cleaved the thymus myosin heavy chain at an additional site about 4000 daltons from the N-terminus. Cleavage at this site caused a 2-fold increase in the ethylenediaminetetraacetic acid-ATPase activity and 3-fold decreases in the Ca 2+ - and Mg-ATPase activities of thymus myosin. Thus, cleavage at the N-terminus of thymus myosin was affected by ATP, and this cleavage altered ATPase activity. Papain cleaved the thymus myosin heavy chain about 94,000 daltons from the N-terminus to give subfragment 1. Although this subfragment 1 contained intact light chains, its actin-activated ATPase activity was not affected by light chain phosphorylation

Inhibition of dipeptidyl peptidase-4: The mechanisms of action and clinical use of vildagliptin for the management of type 2 diabetes

Directory of Open Access Journals (Sweden)

Galina Smushkin

2009-06-01

Full Text Available Galina Smushkin, Adrian VellaDivision of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, MN, USAAbstract: Postprandial hyperglycemia in type 2 diabetes is characterized by impaired insulin secretion and action, decreased glucose effectiveness and defective suppression of glucagon secretion. Newly available therapies for type 2 diabetes target the pathway of the incretin hormone glucagon-like peptide-1 (GLP-1. Oral inhibitors of dipeptidyl peptidase-4 (DPP-4 raise the level of endogenous GLP-1 by inhibiting its clearance thereby lowering fasting and postprandial glucose concentrations. Unlike compounds which act as agonists of the GLP-1 receptor, DPP-4 inhibitors are not associated with significant effects on gastrointestinal motility, which led to a controversy around the mechanisms responsible for their glucose-lowering effects. Here we review the evidence in regards to the mechanisms whereby DPP-4 inhibitors lower glucose concentrations. Their effects are most likely mediated by an increase in endogenous GLP-1, although additional mechanisms may be involved. The pharmacology, efficacy and safety of vildagliptin, a novel DPP-4 inhibitor, are also discussed.Keywords: insulin secretion, insulin action, incretin, DPP-4 inhibitor, glucagon-like peptide 1

Regulatory Proteolysis in Arabidopsis-Pathogen Interactions.

Science.gov (United States)

Pogány, Miklós; Dankó, Tamás; Kámán-Tóth, Evelin; Schwarczinger, Ildikó; Bozsó, Zoltán

2015-09-24

Approximately two and a half percent of protein coding genes in Arabidopsis encode enzymes with known or putative proteolytic activity. Proteases possess not only common housekeeping functions by recycling nonfunctional proteins. By irreversibly cleaving other proteins, they regulate crucial developmental processes and control responses to environmental changes. Regulatory proteolysis is also indispensable in interactions between plants and their microbial pathogens. Proteolytic cleavage is simultaneously used both by plant cells, to recognize and inactivate invading pathogens, and by microbes, to overcome the immune system of the plant and successfully colonize host cells. In this review, we present available results on the group of proteases in the model plant Arabidopsis thaliana whose functions in microbial pathogenesis were confirmed. Pathogen-derived proteolytic factors are also discussed when they are involved in the cleavage of host metabolites. Considering the wealth of review papers available in the field of the ubiquitin-26S proteasome system results on the ubiquitin cascade are not presented. Arabidopsis and its pathogens are conferred with abundant sets of proteases. This review compiles a list of those that are apparently involved in an interaction between the plant and its pathogens, also presenting their molecular partners when available.

Effect of the Glucagon-like Peptide-1 Analogue Exenatide Extended Release in Cats with Newly Diagnosed Diabetes Mellitus.

Science.gov (United States)

Riederer, A; Zini, E; Salesov, E; Fracassi, F; Padrutt, I; Macha, K; Stöckle, T M; Lutz, T A; Reusch, C E

2016-01-01

Exenatide extended release (ER) is a glucagon-like peptide-1 analogue that increases insulin secretion, inhibits glucagon secretion and induces satiation in humans with type 2 diabetes mellitus. The use of exenatide ER is safe and stimulates insulin secretion in healthy cats. The objective of this study is to assess the safety of exenatide ER and its effect on body weight, remission and metabolic control in newly diagnosed diabetic cats receiving insulin and a low-carbohydrate diet. Thirty client-owned cats. Prospective placebo-controlled clinical trial. Cats were treated with exenatide ER or 0.9% saline, administered SC, once weekly. Both groups received insulin glargine and a low-carbohydrate diet. Exenatide ER was administered for 16 weeks, or in cats that achieved remission it was given for 4 weeks after discontinuing insulin treatment. Nonparametric tests were used for statistical analysis. Cats in the exenatide ER and placebo groups had transient adverse signs including decreased appetite (60% vs. 20%, respectively, P = .06) and vomiting (53% vs. 40%, respectively, P = .715). Body weight increased significantly in the placebo group (P = .002), but not in cats receiving exenatide ER. Cats on exenatide ER achieved remission or good metabolic control in 40% or 89%, respectively, whereas in control cats percentages were 20% or 58% (P = .427 and P = .178, respectively). Exenatide ER is safe in diabetic cats and does not result in weight gain. Our pilot study suggests that, should there be an additional clinically relevant beneficial effect of exenatide ER in insulin-treated cats on rate of remission and good metabolic control, it would likely approximate 20% and 30%, respectively. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Effect of pulp preconditioning on acidification, proteolysis, sugars and free fatty acids concentration during fermentation of cocoa (Theobroma cacao) beans.

Science.gov (United States)

Afoakwa, Emmanuel Ohene; Quao, Jennifer; Budu, Agnes Simpson; Takrama, Jemmy; Saalia, Firibu Kwesi

2011-11-01

Changes in acidification, proteolysis, sugars and free fatty acids (FFAs) concentrations of Ghanaian cocoa beans as affected by pulp preconditioning (pod storage or PS) and fermentation were investigated. Non-volatile acidity, pH, proteolysis, sugars (total, reducing and non-reducing) and FFAs concentrations were analysed using standard methods. Increasing PS consistently decreased the non-volatile acidity with concomitant increase in pH during fermentation of the beans. Fermentation decreased the pH of the unstored beans from 6.7 to 4.9 within the first 4 days and then increased slightly again to 5.3 by the sixth day. Protein, total sugars and non-reducing sugars decreased significantly (p cocoa beans was largely affected by fermentation than by PS.

Glucagon-like peptide-2 induces rapid digestive adaptation following intestinal resection in preterm neonates

Science.gov (United States)

Short bowel syndrome (SBS) is a frequent complication after intestinal resection in infants suffering from intestinal disease. We tested whether treatment with the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) increases intestinal volume and function in the period immediately following in...

Exaggerated glucagon-like peptide-1 and blunted glucose-dependent insulinotropic peptide secretion are associated with Roux-en-Y gastric bypass but not adjustable gastric banding

DEFF Research Database (Denmark)

Korner, Judith; Bessler, Marc; Inabnet, William

2007-01-01

BACKGROUND: The aim of this study was to measure the circulating levels of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon in patients who had undergone adjustable gastric banding (BND) or Roux-en-Y gastric bypass (RYGB) to understand the differences...

Proteolysis targeting peptide (PROTAP) strategy for protein ubiquitination and degradation.

Science.gov (United States)

Zheng, Jing; Tan, Chunyan; Xue, Pengcheng; Cao, Jiakun; Liu, Feng; Tan, Ying; Jiang, Yuyang

2016-02-19

Ubiquitination proteasome pathway (UPP) is the most important and selective way to degrade proteins in vivo. Here, a novel proteolysis targeting peptide (PROTAP) strategy, composed of a target protein binding peptide, a linker and a ubiquitin E3 ligase recognition peptide, was designed to recruit both target protein and E3 ligase and then induce polyubiquitination and degradation of the target protein through UPP. In our study, the PROTAP strategy was proved to be a general method with high specificity using Bcl-xL protein as model target in vitro and in cells, which indicates that the strategy has great potential for in vivo application. Copyright © 2016 Elsevier Inc. All rights reserved.

Radio-immunoassays for glucagon-like peptides 1 and 2 (GLP-1 and GLP-2)

DEFF Research Database (Denmark)

Orskov, C; Holst, J J

1987-01-01

in rabbits after carbodiimide conjugation of peptides to BSA. The selected antisera showed neither mutual cross-reactivity nor cross-reacted with any other peptide of the glucagon family. Trypsin digestion experiments showed that both antisera were directed against the C-terminus of the antigen peptides...

Insulin alleviates degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system in septic rats.

Science.gov (United States)

Chen, Qiyi; Li, Ning; Zhu, Weiming; Li, Weiqin; Tang, Shaoqiu; Yu, Wenkui; Gao, Tao; Zhang, Juanjuan; Li, Jieshou

2011-06-03

Hypercatabolism is common under septic conditions. Skeletal muscle is the main target organ for hypercatabolism, and this phenomenon is a vital factor in the deterioration of recovery in septic patients. In skeletal muscle, activation of the ubiquitin-proteasome system plays an important role in hypercatabolism under septic status. Insulin is a vital anticatabolic hormone and previous evidence suggests that insulin administration inhibits various steps in the ubiquitin-proteasome system. However, whether insulin can alleviate the degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system under septic condition is unclear. This paper confirmed that mRNA and protein levels of the ubiquitin-proteasome system were upregulated and molecular markers of skeletal muscle proteolysis (tyrosine and 3-methylhistidine) simultaneously increased in the skeletal muscle of septic rats. Septic rats were infused with insulin at a constant rate of 2.4 mU.kg-1.min-1 for 8 hours. Concentrations of mRNA and proteins of the ubiquitin-proteasome system and molecular markers of skeletal muscle proteolysis were mildly affected. When the insulin infusion dose increased to 4.8 mU.kg-1.min-1, mRNA for ubiquitin, E2-14 KDa, and the C2 subunit were all sharply downregulated. At the same time, the levels of ubiquitinated proteins, E2-14KDa, and the C2 subunit protein were significantly reduced. Tyrosine and 3-methylhistidine decreased significantly. We concluded that the ubiquitin-proteasome system is important skeletal muscle hypercatabolism in septic rats. Infusion of insulin can reverse the detrimental metabolism of skeletal muscle by inhibiting the ubiquitin-proteasome system, and the effect is proportional to the insulin infusion dose.

Proteolysis of proBDNF is a key regulator in the formation of memory.

Directory of Open Access Journals (Sweden)

Philip Barnes

2008-09-01

Full Text Available It is essential to understand the molecular processes underlying long-term memory to provide therapeutic targets of aberrant memory that produce pathological behaviour in humans. Under conditions of recall, fully-consolidated memories can undergo reconsolidation or extinction. These retrieval-mediated memory processes may rely on distinct molecular processes. The cellular mechanisms initiating the signature molecular events are not known. Using infusions of protein synthesis inhibitors, antisense oligonucleotide targeting brain-derived neurotrophic factor (BDNF mRNA or tPA-STOP (an inhibitor of the proteolysis of BDNF protein into the hippocampus of the awake rat, we show that acquisition and extinction of contextual fear memory depended on the increased and decreased proteolysis of proBDNF (precursor BDNF in the hippocampus, respectively. Conditions of retrieval that are known to initiate the reconsolidation of contextual fear memory, a BDNF-independent memory process, were not correlated with altered proBDNF cleavage. Thus, the processing of BDNF was associated with the acquisition of new information and the updating of information about a salient stimulus. Furthermore, the differential requirement for the processing of proBDNF by tPA in distinct memory processes suggest that the molecular events actively engaged to support the storage and/or the successful retrieval of memory depends on the integration of ongoing experience with past learning.

SGLT2 inhibition in the diabetic kidney – an update

Science.gov (United States)

Novikov, Aleksandra; Vallon, Volker

2016-01-01

Purpose of review The sodium glucose cotransporter SGLT2 reabsorbs most of the glucose filtered by the kidneys. SGLT2 inhibitors reduce glucose reabsorption thereby lowering blood glucose levels and have been approved as new anti-hyperglycemic drugs. While the therapeutic strategy is very promising, many questions remain. Recent findings Using validated antibodies SGLT2 expression was localized to the brush border of the early proximal tubule in human kidney and was found upregulated in genetic murine models of type 1 and 2 diabetes. SGLT2 may functionally interact with the Na/H exchanger NHE3 in the proximal tubule. SGLT1-mediated reabsorption explains the fractional glucose reabsorption of 40–50% during SGLT2 inhibition. SGLT2 is expressed on pancreatic alpha cells where its inhibition induces glucagon secretion. SGLT2 inhibition lowers GFR in hyperfiltering diabetic patients consistent with the tubular hypothesis of diabetic hyperfiltration. New data indicate a potential of SGLT2 inhibition for renal medullary hypoxia and ketoacidosis, but also for blood glucose effect-dependent and independent nephroprotective actions, renal gluconeogenesis inhibition, reduction in cardiovascular mortality, and cancer therapy. Summary The findings expand and refine our understanding of SGLT2 and its inhibition, have relevance for clinical practice, and will help interpret ongoing clinical trials on the long-term safety and cardiovascular effects of SGLT2 inhibitors. PMID:26575393

Increased Postprandial GIP and Glucagon Responses, But Unaltered GLP-1 Response after Intervention with Steroid Hormone, Relative Physical Inactivity, And High-Calorie Diet in Healthy Subjects

DEFF Research Database (Denmark)

Hansen, Katrine B; Vilsbøll, Tina; Bagger, Jonatan I

2011-01-01

Objective:Increased postprandial glucose-dependent insulinotropic polypeptide (GIP) and glucagon responses and reduced postprandial glucagon-like peptide-1 (GLP-1) responses have been observed in some patients with type 2 diabetes mellitus. The causality of these pathophysiological traits...... postprandial GLP-1 responses as observed in some individuals with type 2 diabetes mellitus....... is unknown. We aimed to determine the impact of insulin resistance and reduced glucose tolerance on postprandial GIP, GLP-1, and glucagon responses in healthy subjects. Research Design and Methods:A 4-h 2200 KJ-liquid meal test was performed in 10 healthy Caucasian males without family history of diabetes...

Proteolysis of Sardine (Sardina pilchardus and Anchovy (Stolephorus commersonii by Commercial Enzymes in Saline Solutions

Directory of Open Access Journals (Sweden)

Chau Minh Le

2015-01-01

Full Text Available Fish sauce production is a very long process and there is a great interest in shortening it. Among the different strategies to speed up this process, the addition of external proteases could be a solution. This study focuses on the eff ect of two commercial enzymes (Protamex and Protex 51FP on the proteolysis of two fish species traditionally converted into fish sauce: sardine and anchovy, by comparison with classical autolysis. Hydrolysis reactions were conducted with fresh fish at a temperature of 30 °C and under different saline conditions (from 0 to 30 % NaCl. Hydrolysis degree and liquefaction of the raw material were used to follow the process. As expected, the proteolysis decreased with increasing amount of salt. Regarding the fi sh species, higher rate of liquefaction and higher hydrolysis degree were obtained with anchovy. Between the two proteases, Protex 51FP gave better results with both fi sh types. This study demonstrates that the addition of commercial proteases could be helpful for the liquefaction of fi sh and cleavage of peptide bonds that occur during fi sh sauce production and thus speed up the production process.

The Relationship between Glucagon-Like Peptide 2 and Feeding Intolerance in Preterm Infants

DEFF Research Database (Denmark)

Ozer, Esra Arun; Holst, Jens Juul; Duman, Nuray

2008-01-01

Glucagon-like peptide 2 (GLP-2) is a hormone produced primarily in the distal intestine, stimulated by enteral nutrients, and playing diverse roles in the intestinal adaptation and growth. We aimed to investigate whether GLP-2 may play a role in the development of feeding intolerance which is a c...... with low levels of GLP-2 carry a risk for development of feeding intolerance. It may, therefore, be of relevance to investigate the therapeutic and prophylactic effects of GLP-2 administration in the preterm babies.......Glucagon-like peptide 2 (GLP-2) is a hormone produced primarily in the distal intestine, stimulated by enteral nutrients, and playing diverse roles in the intestinal adaptation and growth. We aimed to investigate whether GLP-2 may play a role in the development of feeding intolerance which...... is a common problem in preterm newborns resulting from the intestinal immaturity. The study included 20 term and 28 preterm neonates. Of preterm babies, 13 showed feeding intolerance fulfilling at least one of the following criteria: abdominal distension, increased gastric residual volume and presence of bile...

CONTRIBUTION OF LIVER NERVES, GLUCAGON, AND ADRENALINE TO THE GLYCEMIC RESPONSE TO EXERCISE IN RATS

NARCIS (Netherlands)

VAN DIJK, G; BALKAN, B; LINDFELDT, J; BOUWS, G; SCHEURINK, AJW; AHREN, B; STEFFENS, AB

The contribution of hepatic sympathetic innervation, glucagon and adrenaline to the glycaemic response to exercise was investigated in rats. Hepatically denervated (LDX) or sham operated (SHAM) rats with permanent catheters were therefore submitted to swimming with or without infusion of

Contribution of liver nerves, glucagon, and adrenaline to the glycaemic response to exercise in rats

NARCIS (Netherlands)

van Dijk, Gertjan; Balkan, B.; Lindfeldt, J.; Bouws, G.; Scheurink, A.J.W.; Ahrén, B.; Steffens, A.B.

1994-01-01

The contribution of hepatic sympathetic innervation, glucagon and adrenaline to the glycaemic response to exercise was investigated in rats. Hepatically denervated (LDX) or sham operated (SHAM) rats with permanent catheters were therefore submitted to swimming with or without infusion of

Allosteric regulation of rhomboid intramembrane proteolysis.

Science.gov (United States)

Arutyunova, Elena; Panwar, Pankaj; Skiba, Pauline M; Gale, Nicola; Mak, Michelle W; Lemieux, M Joanne

2014-09-01

Proteolysis within the lipid bilayer is poorly understood, in particular the regulation of substrate cleavage. Rhomboids are a family of ubiquitous intramembrane serine proteases that harbour a buried active site and are known to cleave transmembrane substrates with broad specificity. In vitro gel and Förster resonance energy transfer (FRET)-based kinetic assays were developed to analyse cleavage of the transmembrane substrate psTatA (TatA from Providencia stuartii). We demonstrate significant differences in catalytic efficiency (kcat/K0.5) values for transmembrane substrate psTatA (TatA from Providencia stuartii) cleavage for three rhomboids: AarA from P. stuartii, ecGlpG from Escherichia coli and hiGlpG from Haemophilus influenzae demonstrating that rhomboids specifically recognize this substrate. Furthermore, binding of psTatA occurs with positive cooperativity. Competitive binding studies reveal an exosite-mediated mode of substrate binding, indicating allostery plays a role in substrate catalysis. We reveal that exosite formation is dependent on the oligomeric state of rhomboids, and when dimers are dissociated, allosteric substrate activation is not observed. We present a novel mechanism for specific substrate cleavage involving several dynamic processes including positive cooperativity and homotropic allostery for this interesting class of intramembrane proteases. © 2014 The Authors.

Autophagic dysfunction in a lysosomal storage disorder due to impaired proteolysis.

Science.gov (United States)

Elrick, Matthew J; Lieberman, Andrew P

2013-02-01

Alterations in macroautophagy (hereafter referred to as "autophagy") are a common feature of lysosomal storage disorders, and have been hypothesized to play a major role in the pathogenesis of these diseases. We have recently reported multiple defects in autophagy contributing to the lysosomal storage disorder Niemann-Pick type C (NPC). These include increased formation of autophagosomes, slowed turnover of autophagosomes secondary to impaired lysosomal proteolysis, and delivery of stored lipids to the lysosome via autophagy. The study summarized here describes novel methods for the interrogation of individual stages of the autophagic pathway, and suggests mechanisms by which lipid storage may result in broader lysosomal dysfunction.

Acute disruption of glucagon secretion or action does not improve glucose tolerance in an insulin-deficient mouse model of diabetes

DEFF Research Database (Denmark)

Steenberg, Vivi R.; Jensen, Signe Marie; Pedersen, Jens

2016-01-01

receptor antagonism, in order to evaluate the effect of these on glucose tolerance. Methods: Severe diabetes was induced in transgenic and wild-type mice by streptozotocin. Glucose metab. was investigated using OGTT in transgenic mice with the human diphtheria toxin receptor expressed in proglucagon...... producing cells allowing for diphtheria toxin (DT)-induced alpha cell ablation and in mice treated with either a specific high affinity glucagon antibody or a specific glucagon receptor antagonist. Results: Near-total alpha cell elimination was induced in transgenic mice upon DT administration and resulted...

Characterization of glucagon-like peptide-1 receptor beta-arrestin 2 interaction: a high-affinity receptor phenotype

DEFF Research Database (Denmark)

Jorgensen, Rasmus; Martini, Lene; Schwartz, Thue W

2005-01-01

To dissect the interaction between beta-arrestin ((beta)arr) and family B G protein-coupled receptors, we constructed fusion proteins between the glucagon-like peptide 1 receptor and (beta)arr2. The fusion constructs had an increase in apparent affinity selectively for glucagon, suggesting...... that (beta)arr2 interaction locks the receptor in a high-affinity conformation, which can be explored by some, but not all, ligands. The fusion constructs adopted a signaling phenotype governed by the tethered (beta)arr2 with an attenuated G protein-mediated cAMP signal and a higher maximal internalization...... of that which has previously been characterized for family A G protein-coupled receptors, suggesting similarities in the effect of (beta)arr interaction between family A and B receptors also at the molecular level....

Phenylalanine metabolism in isolated rat liver cells. Effects of glucagon and diabetes.

OpenAIRE

Carr, F P; Pogson, C I

1981-01-01

1. Methods are described for monitoring the metabolic flux through phenylalanine hydroxylase, the tyrosine catabolic pathway and phenylalanine: pyruvate transaminase in isolated liver cell incubations. 2. The relationship between hydroxylase flux and phenylalanine concentration is sigmoidal. 3. Glucagon increases hydroxylase activity at low, near-physiological, substrate concentrations only. The hormone does not affect the rate of formation of phenylpyruvate. 4. Experimental diabetes (for 10 ...

Conformational changes in DNA gyrase revealed by limited proteolysis

DEFF Research Database (Denmark)

Kampranis, S C; Maxwell, A

1998-01-01

We have used limited proteolysis to identify conformational changes in DNA gyrase. Gyrase exhibits a proteolytic fingerprint dominated by two fragments, one of approximately 62 kDa, deriving from the A protein, and another of approximately 25 kDa from the B protein. Quinolone binding to the enzyme......-DNA intermediate by calcium ions does not reveal any protection, suggesting that the quinolone-induced conformational change is different from an "open-gate" state of the enzyme. A quinolone-resistant mutant of gyrase fails to give the characteristic quinolone-associated proteolytic signature. The ATP...... does not prevent dimerization since incubation of the enzyme-DNA complex with both ADPNP and quinolones gives rise to a complex whose proteolytic pattern retains the characteristic signature of dimerization but has lost the quinolone-induced protection. As a result, the quinolone-gyrase complex can...

A fasting inducible switch modulates gluconeogenesis via activator/coactivator exchange

DEFF Research Database (Denmark)

Liu, Yi; Dentin, Renaud; Chen, Danica

2008-01-01

During early fasting, increases in skeletal muscle proteolysis liberate free amino acids for hepatic gluconeogenesis in response to pancreatic glucagon. Hepatic glucose output diminishes during the late protein-sparing phase of fasting, when ketone body production by the liver supplies compensatory...... expression through the dephosphorylation and nuclear shuttling of forkhead box O1 (FOXO1). Here we show that a fasting-inducible switch, consisting of the histone acetyltransferase p300 and the nutrient-sensing deacetylase sirtuin 1 (SIRT1), maintains energy balance in mice through the sequential induction...... of CRTC2 and FOXO1. After glucagon induction, CRTC2 stimulated gluconeogenic gene expression by an association with p300, which we show here is also activated by dephosphorylation at Ser 89 during fasting. In turn, p300 increased hepatic CRTC2 activity by acetylating it at Lys 628, a site that also...

Additive glucose-lowering effects of glucagon-like peptide-1 and metformin in type 2 diabetes

DEFF Research Database (Denmark)

Zander, M; Taskiran, M; Toft-Nielsen, M B

2001-01-01

) alternating with GLP-1 (continuous subcutaneous infusion of 2.4 pmol x kg(-1) x min(-1)) alternating with a combination of metformin and GLP-1 for 48 h. Under fixed energy intake, we examined the effects on plasma glucose, insulin, C-peptide, glucagon, and appetite. RESULTS: Fasting plasma glucose (day 2...... this study to investigate the effect of a combination therapy with GLP-1 and metformin, which could theoretically be additive, in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: In a semiblinded randomized crossover study, seven patients received treatment with metformin (1,500 mg daily orally......) and 11.7 +/- 0.8 (GLP-1) to 9.8 +/- 0.5 (combination) (P = 0.02, no difference between GLP-1 and metformin). Insulin levels were similar between the three regimens, but glucagon levels were significantly reduced with GLP-1 compared with metformin (P = 0.0003). Combination therapy had no additional effect...

The beta-cell response to glucagon and mixed meal stimulation in non-insulin dependent diabetes

DEFF Research Database (Denmark)

Gjessing, H J; Damsgaard, E M; Matzen, L E

1988-01-01

The aim of this study was to evaluate the correlations of the C-peptide and insulin responses after stimulation with glucagon intravenously as well as the 24-h urinary excretion of C-peptide to the C-peptide response to a standard mixed meal in 30 patients with non-insulin dependent diabetes...... plasma C-peptide (r = 0.55, p less than 0.01). The C-peptide and insulin responses after meal stimulation correlated modestly inversely with HbA1. In conclusion, measurement of C-peptide in fasting state, as well as measurements of C-peptide and insulin after glucagon stimulation, only modestly predict...... the C-peptide response to physiologic stimulation in NIDDM. Twenty-four-hour urinary C-peptide excretion does not predict this response. Patients with NIDDM seem to show a better metabolic control if they have a more pronounced beta-cell response to physiologic stimulation....

Integrative function of adrenaline receptors for glucagon-like peptide-1 exocytosis in enteroendocrine L cell line GLUTag.

Science.gov (United States)

Harada, Kazuki; Kitaguchi, Tetsuya; Tsuboi, Takashi

2015-05-15

Adrenaline reacts with three types of adrenergic receptors, α1, α2 and β-adrenergic receptors (ARs), inducing many physiological events including exocytosis. Although adrenaline has been shown to induce glucagon-like peptide-1 (GLP-1) secretion from intestinal L cells, the precise molecular mechanism by which adrenaline regulates GLP-1 secretion remains unknown. Here we show by live cell imaging that all types of adrenergic receptors are stimulated by adrenaline in enteroendocrine L cell line GLUTag cells and are involved in GLP-1 exocytosis. We performed RT-PCR analysis and found that α1B-, α2A-, α2B-, and β1-ARs were expressed in GLUTag cells. Application of adrenaline induced a significant increase of intracellular Ca(2+) and cAMP concentration ([Ca(2+)]i and [cAMP]i, respectively), and GLP-1 exocytosis in GLUTag cells. Blockade of α1-AR inhibited adrenaline-induced [Ca(2+)]i increase and exocytosis but not [cAMP]i increase, while blockade of β1-AR inhibited adrenaline-induced [cAMP]i increase and exocytosis but not [Ca(2+)]i increase. Furthermore, overexpression of α2A-AR suppressed the adrenaline-induced [cAMP]i increase and exocytosis. These results suggest that the fine-turning of GLP-1 secretion from enteroendocrine L cells is established by the balance between α1-, α2-, and β-ARs activation. Copyright © 2015 Elsevier Inc. All rights reserved.

Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

Energy Technology Data Exchange (ETDEWEB)

Goto, Hiromasa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Nomiyama, Takashi, E-mail: tnomiyama@fukuoka-u.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Kawamori, Ryuzo [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Beta Cell Biology and Regeneration, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Fujitani, Yoshio; Hirose, Takahisa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Watada, Hirotaka, E-mail: hwatada@juntendo.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan)

2011-02-04

Research highlights: {yields} Exendin-4 reduces neointimal formation after vascular injury in a mouse model. {yields} Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. {yields} Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. {yields} Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

International Nuclear Information System (INIS)

Goto, Hiromasa; Nomiyama, Takashi; Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio; Kawamori, Ryuzo; Fujitani, Yoshio; Hirose, Takahisa; Watada, Hirotaka

2011-01-01

Research highlights: → Exendin-4 reduces neointimal formation after vascular injury in a mouse model. → Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. → Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. → Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Glucagon-like Peptide-1 and the Central/Peripheral Nervous System

DEFF Research Database (Denmark)

Muscogiuri, Giovanna; DeFronzo, Ralph A; Gastaldelli, Amalia

2017-01-01

Glucagon-like peptide-1 (GLP-1) is released in response to meals and exerts important roles in the maintenance of normal glucose homeostasis. GLP-1 is also important in the regulation of neurologic and cognitive functions. These actions are mediated via neurons in the nucleus of the solitary trac...... human trials report a neuroprotective effect of GLP-1-RAs in Alzheimer's and Parkinson's disease. In this review, we discuss the role of GLP-1 and GLP-1-RAs in the nervous system with focus on GLP-1 actions on appetite regulation, glucose homeostasis, and neuroprotection....

Does Glucagon-like Peptide-1 Ameliorate Oxidative Stress in Diabetes?

DEFF Research Database (Denmark)

Petersen, Karen Ekkelund; Rakipovski, Günaj; Raun, Kirsten

2016-01-01

Glucagon-like peptide-1 (GLP-1) has shown to influence the oxidative stress status in a number of in vitro, in vivo and clinical studies. Well-known effects of GLP-1 including better glycemic control, decreased food intake, increased insulin release and increased insulin sensitivity may indirectly...... a controversial topic but could hold a therapeutic potential against micro- and macrovascular diabetic complications. This review discusses the presently available knowledge from experimental and clinical studies on the effects of GLP-1 on oxidative stress in diabetes and diabetes-related complications....

Additive effects of glucagon-like peptide 1 and pioglitazone in patients with type 2 diabetes

DEFF Research Database (Denmark)

Zander, Mette; Christiansen, Allan; Madsbad, Sten

2004-01-01

.01). Glucagon levels were reduced in GLP-1 and combination therapy compared with saline and monotherapy with pioglitazone (P breakfast (area under the curve, 0-3 h) were reduced in combination therapy compared with saline (P = 0.03). Sensation of appetite was reduced during monotherapy...

Effect of chenodeoxycholic acid and the bile acid sequestrant colesevelam on glucagon-like peptide-1 secretion

DEFF Research Database (Denmark)

Hansen, Morten; Scheltema, Matthijs J; Sonne, David P

2016-01-01

AIMS: In patients with type 2 diabetes, rectal administration of bile acids increases glucagon-like peptide-1 (GLP-1) secretion and reduces plasma glucose. In addition, oral bile acid sequestrants (BASs) reduce blood glucose by an unknown mechanism. In this study we evaluated the effects...... of the primary human bile acid, chenodeoxycholic acid (CDCA), and the BAS, colesevelam, instilled into the stomach, on plasma levels of GLP-1, glucose-dependent insulinotropic polypeptide, glucose, insulin, C-peptide, glucagon, cholecystokinin and gastrin as well as gastric emptying, gallbladder volume, appetite......, and delayed gastric emptying. We speculate that bile acid-induced activation of TGR5 on L cells increases GLP-1 secretion, which in turn may result in amplification of glucose-stimulated insulin secretion. Furthermore our data suggest that colesevelam does not have an acute effect on GLP-1 secretion in humans....

The effect of nutrition on immunoreactive glucagon and its related forms occurring in the gut, pancreas and plasma of normal and pancreatectomised pigs

International Nuclear Information System (INIS)

Fourie, A.J.

1983-08-01

This thesis deals with the short-term effects of feeding or starvation upon the distribution of molecular species of glucagon in the gastrointestinal tissues, pancreas and blood entering and leaving the liver and kidney of sham operated or pancreatectomised pigs. The glucagon was quantitated by radioammunoassay. Further characterization of the molecular species present was made using gel filtration chromatography, and also by enzymatic digestion of extracted samples with trypsin or trypsin followed by carboxypeptidase

Normalization of glucose concentrations and deceleration of gastric emptying after solid meals during intravenous glucagon-like peptide 1 in patients with type 2 diabetes

DEFF Research Database (Denmark)

Meier, Juris J; Gallwitz, Baptist; Salmen, Stefan

2003-01-01

in the fasting state and after a solid test meal (containing [(13)C]octanoic acid). Blood was drawn for glucose, insulin, C-peptide, glucagon, and GLP-1 determinations. The gastric emptying rate was calculated from the (13)CO(2) excretion rates in breath samples. Statistics were determined using repeated......The effects of different i.v. doses of glucagon-like peptide 1 (GLP-1) on glucose homeostasis and gastric emptying were compared in patients with type 2 diabetes. Twelve patients with type 2 diabetes received three different infusion rates of GLP-1 (0.4, 0.8, and 1.2 pmol/kg x min) or placebo...... ingestion (P = 0.0031 and 0.0074, respectively). Glucagon secretion was suppressed with GLP-1. Gastric emptying was decelerated by GLP-1 in a dose-dependent fashion (P

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

Science.gov (United States)

Thompson, Aiysha; Stephens, Jeffrey W; Bain, Stephen C; Kanamarlapudi, Venkateswarlu

2016-01-01

The glucagon-like peptide receptor (GLP-1R), which is a G-protein coupled receptor (GPCR), signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R) expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39) and JANT-4 and the orthosteric binding site mutation (V36A) in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

Directory of Open Access Journals (Sweden)

Aiysha Thompson

Full Text Available The glucagon-like peptide receptor (GLP-1R, which is a G-protein coupled receptor (GPCR, signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39 and JANT-4 and the orthosteric binding site mutation (V36A in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

Proteolysis of virulence regulator ToxR is associated with entry of Vibrio cholerae into a dormant state.

Directory of Open Access Journals (Sweden)

Salvador Almagro-Moreno

2015-04-01

Full Text Available Vibrio cholerae O1 is a natural inhabitant of aquatic environments and causes the diarrheal disease, cholera. Two of its primary virulence regulators, TcpP and ToxR, are localized in the inner membrane. TcpP is encoded on the Vibrio Pathogenicity Island (VPI, a horizontally acquired mobile genetic element, and functions primarily in virulence gene regulation. TcpP has been shown to undergo regulated intramembrane proteolysis (RIP in response to environmental conditions that are unfavorable for virulence gene expression. ToxR is encoded in the ancestral genome and is present in non-pathogenic strains of V. cholerae, indicating it has roles outside of the human host. In this study, we show that ToxR undergoes RIP in V. cholerae in response to nutrient limitation at alkaline pH, a condition that occurs during the stationary phase of growth. This process involves the site-2 protease RseP (YaeL, and is dependent upon the RpoE-mediated periplasmic stress response, as deletion mutants for the genes encoding these two proteins cannot proteolyze ToxR under nutrient limitation at alkaline pH. We determined that the loss of ToxR, genetically or by proteolysis, is associated with entry of V. cholerae into a dormant state in which the bacterium is normally found in the aquatic environment called viable but nonculturable (VBNC. Strains that can proteolyze ToxR, or do not encode it, lose culturability, experience a change in morphology associated with cells in VBNC, yet remain viable under nutrient limitation at alkaline pH. On the other hand, mutant strains that cannot proteolyze ToxR remain culturable and maintain the morphology of cells in an active state of growth. Overall, our findings provide a link between the proteolysis of a virulence regulator and the entry of a pathogen into an environmentally persistent state.

Effects of subcutaneous, low-dose glucagon on insulin-induced mild hypoglycaemia in patients with insulin pump treated type 1 diabetes

DEFF Research Database (Denmark)

Ranjan, Ajenthen; Schmidt, S; Madsbad, Sten

2016-01-01

AIM: To investigate the dose-response relationship of subcutaneous glucagon administration on plasma glucose and on counterregulatory hormone responses during subcutaneous insulin induced mild hypoglycaemia in patients with type 1 diabetes treated with insulin pumps. MATERIALS AND METHODS: Eight...... hypoglycaemia in patients with type 1 diabetes....... insulin pump treated patients completed a blinded, randomized, placebo-controlled study. Hypoglycaemia was induced in the fasting state by a subcutaneous insulin bolus and when plasma glucose reached 3.4 mmol/l (95%CI 3.2-3.5), a subcutaneous bolus of either 100, 200, 300 µg glucagon or saline...

The role of extracellular proteolysis in synaptic plasticity of the central nervous system 

Directory of Open Access Journals (Sweden)

Anna Konopka

2012-11-01

Full Text Available The extracellular matrix (ECM of the central nervous system has a specific structure and protein composition that are different from those in other organs. Today we know that the ECM not only provides physical scaffolding for the neurons and glia, but also actively modifies their functions. Over the last two decades, a growing body of research evidence has been collected, suggesting an important role of ECM proteolysis in synaptic plasticity of the brain. So far the majority of data concern two large families of proteases: the serine proteases and the matrix metalloproteinases. The members of these families are localized at the synapses, and are secreted into the extracellular space in an activity-dependent manner. The proteases remodel the local environment as well as influencing synapse structure and function. The structural modifications induced by proteases include shape and size changes, as well as synapse elimination, and synaptogenesis. The functional changes include modifications of receptor function in the postsynaptic part of the synapse, as well as the potentiation or depression of neurotransmitter secretion by the presynaptic site. The present review summarizes the current view on the role of extracellular proteolysis in the physiological synaptic plasticity underlying the phenomena of learning and memory, as well as in the pathological plasticity occurring during epileptogenesis or development of drug addiction. 

Impact of microencapsulated peptidase (Aspergillus oryzae) on cheddar cheese proteolysis and its biologically active peptide profile.

Science.gov (United States)

Seneweera, Saman; Kailasapathy, Kaila

2011-07-01

We investigated the delivery of calcium-alginate encapsulated peptidase (Flavourzyme(®), Aspergillus oryzae) on proteolysis of Cheddar cheese. Physical and chemical characteristics such as moisture, pH and fat content were measured, and no differences were found between control and experimental cheese at day 0. SDS-PAGE analysis clearly showed that proteolysis of α and k casein was significantly accelerated after three months of maturity in the experimental cheese. A large number of low molecular weight peptides were found in the water soluble fraction of the experimental cheeses and some of these peptides were new. N-terminal amino acid sequence analysis identified these as P(1), Leu-Thu-Glu; P(3), Asp-Val-Pro-Ser-Glu) and relatively abundant stable peptides P(2), P(4), Arg-Pro-Lys-His-Pro-Ile; P(5), Arg-Pro-Lys-His-Pro-Ile-Lys and P(6). These peptides were mainly originated from αs1-CN and β-CN. Three of the identified peptides (P(1), P(2), P(3) and P(4)) are known to biologically active and P(1) and P(3) were only present in experimental cheese suggesting that experimental cheese has improved health benefits.

A glucagon-like peptide-1 receptor agonist reduces intracranial pressure in a rat model of hydrocephalus

DEFF Research Database (Denmark)

Botfield, Hannah F; Uldall, Maria S; Westgate, Connar S J

2017-01-01

Current therapies for reducing raised intracranial pressure (ICP) under conditions such as idiopathic intracranial hypertension or hydrocephalus have limited efficacy and tolerability. Thus, there is a pressing need to identify alternative drugs. Glucagon-like peptide-1 receptor (GLP-1R) agonists...

Inhibition of PIP4Kγ ameliorates the pathological effects of mutant huntingtin protein.

Science.gov (United States)

Al-Ramahi, Ismael; Panapakkam Giridharan, Sai Srinivas; Chen, Yu-Chi; Patnaik, Samarjit; Safren, Nathaniel; Hasegawa, Junya; de Haro, Maria; Wagner Gee, Amanda K; Titus, Steven A; Jeong, Hyunkyung; Clarke, Jonathan; Krainc, Dimitri; Zheng, Wei; Irvine, Robin F; Barmada, Sami; Ferrer, Marc; Southall, Noel; Weisman, Lois S; Botas, Juan; Marugan, Juan Jose

2017-12-26

The discovery of the causative gene for Huntington's disease (HD) has promoted numerous efforts to uncover cellular pathways that lower levels of mutant huntingtin protein (mHtt) and potentially forestall the appearance of HD-related neurological defects. Using a cell-based model of pathogenic huntingtin expression, we identified a class of compounds that protect cells through selective inhibition of a lipid kinase, PIP4Kγ. Pharmacological inhibition or knock-down of PIP4Kγ modulates the equilibrium between phosphatidylinositide (PI) species within the cell and increases basal autophagy, reducing the total amount of mHtt protein in human patient fibroblasts and aggregates in neurons. In two Drosophila models of Huntington's disease, genetic knockdown of PIP4K ameliorated neuronal dysfunction and degeneration as assessed using motor performance and retinal degeneration assays respectively. Together, these results suggest that PIP4Kγ is a druggable target whose inhibition enhances productive autophagy and mHtt proteolysis, revealing a useful pharmacological point of intervention for the treatment of Huntington's disease, and potentially for other neurodegenerative disorders.

Combined contributions of over-secreted glucagon-like peptide 1 and suppressed insulin secretion to hyperglycemia induced by gatifloxacin in rats

Energy Technology Data Exchange (ETDEWEB)

Yu, Yunli, E-mail: chrisyu1255@yahoo.com.cn [Department of Pharmaceutics, The Second Affiliated Hospital of Soochow University, Suzhou 215004 (China); Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Wang, Xinting, E-mail: wxinting1986@yahoo.com.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Can, E-mail: ltsan@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Yao, Dan, E-mail: erinyao@126.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Shanghai Institute of Materia Medica, Shanghai 201203 (China); Hu, Mengyue, E-mail: juliahmy@126.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Li, Jia, E-mail: ljbzd@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Hu, Nan, E-mail: hn_324@163.com [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Li, E-mail: liulee@cpu.edu.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China); Liu, Xiaodong, E-mail: xdliu@cpu.edu.cn [Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009 (China)

2013-02-01

Accumulating evidences have showed that gatifloxacin causes dysglycemia in both diabetic and non-diabetic patients. Our preliminary study demonstrated that gatifloxacin stimulated glucagon-like peptide 1 (GLP-1) secretion from intestinal cells. The aim of the study was to investigate the association between gatifloxacin-stimulated GLP-1 release and dysglycemia in both normal and streptozotocin-induced diabetic rats and explore the possible mechanisms. Oral administration of gatifloxacin (100 mg/kg/day and 200 mg/kg/day) for 3 and 12 days led to marked elevation of GLP-1 levels, accompanied by significant decrease in insulin levels and increase in plasma glucose. Similar results were found in normal rats treated with 3-day gatifloxacin. Gatifloxacin-stimulated GLP-1 release was further confirmed in NCI-H716 cells, which was abolished by diazoxide, a K{sub ATP} channel opener. QT-PCR analysis showed that gatifloxacin also upregulated expression of proglucagon and prohormone convertase 3 mRNA. To clarify the contradiction on elevated GLP-1 without insulinotropic effect, effects of GLP-1 and gatifloxacin on insulin release were investigated using INS-1 cells. We found that short exposure (2 h) to GLP-1 stimulated insulin secretion and biosynthesis, whereas long exposure (24 h and 48 h) to high level of GLP-1 inhibited insulin secretion and biosynthesis. Moreover, we also confirmed gatifloxacin acutely stimulated insulin secretion while chronically inhibited insulin biosynthesis. All the results gave an inference that gatifloxacin stimulated over-secretion of GLP-1, in turn, high levels of GLP-1 and gatifloxacin synergistically impaired insulin release, worsening hyperglycemia. -- Highlights: ► Gatifloxacin induced hyperglycemia both in diabetic rats and normal rats. ► Gatifloxacin enhanced GLP-1 secretion but inhibited insulin secretion in rats. ► Long-term exposure to high GLP-1 inhibited insulin secretion and biosynthesis. ► GLP-1 over-secretion may be

Combined contributions of over-secreted glucagon-like peptide 1 and suppressed insulin secretion to hyperglycemia induced by gatifloxacin in rats

International Nuclear Information System (INIS)

Yu, Yunli; Wang, Xinting; Liu, Can; Yao, Dan; Hu, Mengyue; Li, Jia; Hu, Nan; Liu, Li; Liu, Xiaodong

2013-01-01

Accumulating evidences have showed that gatifloxacin causes dysglycemia in both diabetic and non-diabetic patients. Our preliminary study demonstrated that gatifloxacin stimulated glucagon-like peptide 1 (GLP-1) secretion from intestinal cells. The aim of the study was to investigate the association between gatifloxacin-stimulated GLP-1 release and dysglycemia in both normal and streptozotocin-induced diabetic rats and explore the possible mechanisms. Oral administration of gatifloxacin (100 mg/kg/day and 200 mg/kg/day) for 3 and 12 days led to marked elevation of GLP-1 levels, accompanied by significant decrease in insulin levels and increase in plasma glucose. Similar results were found in normal rats treated with 3-day gatifloxacin. Gatifloxacin-stimulated GLP-1 release was further confirmed in NCI-H716 cells, which was abolished by diazoxide, a K ATP channel opener. QT-PCR analysis showed that gatifloxacin also upregulated expression of proglucagon and prohormone convertase 3 mRNA. To clarify the contradiction on elevated GLP-1 without insulinotropic effect, effects of GLP-1 and gatifloxacin on insulin release were investigated using INS-1 cells. We found that short exposure (2 h) to GLP-1 stimulated insulin secretion and biosynthesis, whereas long exposure (24 h and 48 h) to high level of GLP-1 inhibited insulin secretion and biosynthesis. Moreover, we also confirmed gatifloxacin acutely stimulated insulin secretion while chronically inhibited insulin biosynthesis. All the results gave an inference that gatifloxacin stimulated over-secretion of GLP-1, in turn, high levels of GLP-1 and gatifloxacin synergistically impaired insulin release, worsening hyperglycemia. -- Highlights: ► Gatifloxacin induced hyperglycemia both in diabetic rats and normal rats. ► Gatifloxacin enhanced GLP-1 secretion but inhibited insulin secretion in rats. ► Long-term exposure to high GLP-1 inhibited insulin secretion and biosynthesis. ► GLP-1 over-secretion may be involved in

The Effect of Glucagon-Like Peptide 1 Receptor Agonists on Weight Loss in Type 2 Diabetes: A Systematic Review and Mixed Treatment Comparison Meta-Analysis.

Directory of Open Access Journals (Sweden)

Jessica E Potts

Full Text Available To determine the effects of glucagon-like peptide-1 receptor agonists compared with placebo and other anti-diabetic agents on weight loss in overweight or obese patients with type 2 diabetes mellitus.Electronic searches were conducted for randomised controlled trials that compared a glucagon-like peptide-1 receptor agonist therapy at a clinically relevant dose with a comparator treatment (other type 2 diabetes treatment or placebo in adults with type 2 diabetes and a mean body mass index ≥ 25 kg/m2. Pair-wise meta-analyses and mixed treatment comparisons were conducted to examine the difference in weight change at six months between the glucagon-like peptide-1 receptor agonists and each comparator.In the mixed treatment comparison (27 trials, the glucagon-like peptide-1 receptor agonists were the most successful in terms of weight loss; exenatide 2 mg/week: -1.62 kg (95% CrI: -2.95 kg, -0.30 kg, exenatide 20 μg: -1.37 kg (95% CI: -222 kg, -0.52 kg, liraglutide 1.2 mg: -1.01 kg (95%CrI: -2.41 kg, 0.38 kg and liraglutide 1.8 mg: -1.51 kg (95% CI: -2.67 kg, -0.37 kg compared with placebo. There were no differences between the GLP-1 receptor agonists in terms of weight loss.This review provides evidence that glucagon-like peptide-1 receptor agonist therapies are associated with weight loss in overweight or obese patients with type 2 diabetes with no difference in weight loss seen between the different types of GLP-1 receptor agonists assessed.

Enzymatically structured emulsions in simulated gastrointestinal environment: impact on interfacial proteolysis and diffusion in intestinal mucus.

Science.gov (United States)

Macierzanka, Adam; Böttger, Franziska; Rigby, Neil M; Lille, Martina; Poutanen, Kaisa; Mills, E N Clare; Mackie, Alan R

2012-12-18

Fundamental knowledge of physicochemical interactions in the gastrointestinal environment is required in order to support rational designing of protein-stabilized colloidal food and pharmaceutical delivery systems with controlled behavior. In this paper, we report on the colloidal behavior of emulsions stabilized with the milk protein sodium caseinate (Na-Cas), and exposed to conditions simulating the human upper gastrointestinal tract. In particular, we looked at how the kinetics of proteolysis was affected by adsorption to an oil-water interface in emulsion and whether the proteolysis and the emulsion stability could be manipulated by enzymatic structuring of the interface. After cross-linking with the enzyme transglutaminase, the protein was digested with use of an in vitro model of gastro-duodenal proteolysis in the presence or absence of physiologically relevant surfactants (phosphatidylcholine, PC; bile salts, BS). Significant differences were found between the rates of digestion of Na-Cas cross-linked in emulsion (adsorbed protein) and in solution. In emulsion, the digestion of a population of polypeptides of M(r) ca. 50-100 kDa was significantly retarded through the gastric digestion. The persistent interfacial polypeptides maintained the original emulsion droplet size and prevented the system from phase separating. Rapid pepsinolysis of adsorbed, non-cross-linked Na-Cas and its displacement by PC led to emulsion destabilization. These results suggest that structuring of emulsions by enzymatic cross-linking of the interfacial protein may affect the phase behavior of emulsion in the stomach and the gastric digestion rate in vivo. Measurements of ζ-potential revealed that BS displaced the remaining protein from the oil droplets during the simulated duodenal phase of digestion. Diffusion of the postdigestion emulsion droplets through ex vivo porcine intestinal mucus was only significant in the presence of BS due to the high negative charge these

Sequence analysis of PROTEOLYSIS 6 from Solanum lycopersicum

Science.gov (United States)

Roslan, Nur Farhana; Chew, Bee Lyn; Goh, Hoe-Han; Isa, Nurulhikma Md

2018-04-01

The N-end rule pathway is a protein degradation pathway that relates the protein half-life with the identity of its N-terminal residues. A destabilizing N-terminal residues is created by enzymatic reaction or chemical modifications. This destabilized substrate will be recognized by PROTEOLYSIS 6 (PRT6) protein, which encodes an E3 ligase enzyme and resulted in substrate degradation by proteasome. PRT6 has been studied in Arabidopsis thaliana and barley but not yet been studied in fleshy fruit plants. Hence, this study was carried out in tomato that is known as the model for fleshy fruit plants. BLASTX analysis identified that Solyc09g010830 which encodes for a PRT6 gene in tomato based on its sequence similarity with PRT6 in A. thaliana. In silico gene expression analysis shows that PRT6 gene was highly expressed in tomato fruits breaker +5. Co-expression analysis shows that PRT6 may not only involved in abiotic stresses but also in biotic stresses. The objective is to analyze the sequence and characterize PRT6 gene in tomato.

Two Alkaloids from Bulbs of Lycoris sanguinea MAXIM. Suppress PEPCK Expression by Inhibiting the Phosphorylation of CREB.

Science.gov (United States)

Yun, Young Sook; Tajima, Miki; Takahashi, Shigeru; Takahashi, Yuji; Umemura, Mariko; Nakano, Haruo; Park, Hyun Sun; Inoue, Hideshi

2016-10-01

In the fasting state, gluconeogenesis is upregulated by glucagon. Glucagon stimulates cyclic adenosine monophosphate production, which induces the expression of key enzymes for gluconeogenesis, such as cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), which are involved in gluconeogenesis through the protein kinase A/cAMP response element-binding protein (CREB) pathway. Using a luciferase reporter gene assay, a methanol extract of the bulbs of Lycoris sanguinea M AXIM. var. kiushiana Makino was found to suppress cAMP-enhanced PEPCK-C promoter activity. In addition, two alkaloids, lycoricidine and lycoricidinol, in the extract were identified as active constituents. In forskolin-stimulated human hepatoma cells, these alkaloids suppressed the expression of a reporter gene under the control of cAMP response element and also prevented increases in the endogenous levels of phosphorylated CREB and PEPCK mRNA expression. These results suggest that lycoricidine and lycoricidinol suppress PEPCK-C expression by inhibiting the phosphorylation of CREB and may thus have the potential to prevent excessive gluconeogenesis in type 2 diabetes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Glutamine-Elicited Secretion of Glucagon-Like Peptide 1 Is Governed by an Activated Glutamate Dehydrogenase.

Science.gov (United States)

Andersson, Lotta E; Shcherbina, Liliya; Al-Majdoub, Mahmoud; Vishnu, Neelanjan; Arroyo, Claudia Balderas; Aste Carrara, Jonathan; Wollheim, Claes B; Fex, Malin; Mulder, Hindrik; Wierup, Nils; Spégel, Peter

2018-03-01

Glucagon-like peptide 1 (GLP-1), secreted from intestinal L cells, glucose dependently stimulates insulin secretion from β-cells. This glucose dependence prevents hypoglycemia, rendering GLP-1 analogs a useful and safe treatment modality in type 2 diabetes. Although the amino acid glutamine is a potent elicitor of GLP-1 secretion, the responsible mechanism remains unclear. We investigated how GLP-1 secretion is metabolically coupled in L cells (GLUTag) and in vivo in mice using the insulin-secreting cell line INS-1 832/13 as reference. A membrane-permeable glutamate analog (dimethylglutamate [DMG]), acting downstream of electrogenic transporters, elicited similar alterations in metabolism as glutamine in both cell lines. Both DMG and glutamine alone elicited GLP-1 secretion in GLUTag cells and in vivo, whereas activation of glutamate dehydrogenase (GDH) was required to stimulate insulin secretion from INS-1 832/13 cells. Pharmacological inhibition in vivo of GDH blocked secretion of GLP-1 in response to DMG. In conclusion, our results suggest that nonelectrogenic nutrient uptake and metabolism play an important role in L cell stimulus-secretion coupling. Metabolism of glutamine and related analogs by GDH in the L cell may explain why GLP-1 secretion, but not that of insulin, is activated by these secretagogues in vivo. © 2017 by the American Diabetes Association.

Problems of the radioimmunological determination of plasmaglucagon

International Nuclear Information System (INIS)

Boettger, I.

1978-01-01

The radioimmunological determination of plasmaglucagon technically needs special sampling and storage of the plasma, inhibition of the proteolytic degradation of I 125 -glucagon during incubation ('incubation damage') by the addition of the proteaseinhibitor aprotinin (Trasylol ) and the use of glucagonantisera which only specifically raceact with pancreatic or 'true' extrapancreatic glucagon, but not with 'gut GLI (glucagon-like immunoreactivity)'. When interpreting the data of the specifically determined total glucagon immunoreactivity (GIR) one has to put into consideration the inclusion in the measurements of the four plasma-GIR-components 'BPG'(big plasma glucagon) or 'interference factor', 'big glucagon' or 'LGI(large glucagon immunoreactivity)' or 'proglucagon', 'true' glucagon, and degradation products of glucagon or it's precursors. In certain cases, following gel filtration, these four fractions have to be put into the glucagon-RIA individually. (orig.) 891 MG [de

Proinsulin, GLP-1, and glucagon are associated with partial remission in children and adolescents with newly diagnosed type 1 diabetes

DEFF Research Database (Denmark)

Kaas, A.; Andersen, M. L. M.; Fredheim, Siri

2012-01-01

.002) were significantly lower in remitters than in non-remitters at 6 and 12 months. Proinsulin associated positively with GLP-1 at 1 month (p = 0.004) and negatively at 6 (p = 0.002) and 12 months (p = 0.0002). Conclusions: In type 1 diabetes, patients in partial remission have higher levels of proinsulin......1C), glucagon-like peptide-1 (GLP-1), glucagon, and remission status the first year after diagnosis of type 1 diabetes. Methods: Juvenile patients (n = 275) were followed 1, 6, and 12 months after diagnosis. At each visit, partial remission was defined as IDAA1C = 9%. The patients had a liquid meal...

A safety and pharmacokinetic dosing study of glucagon-like peptide 2 in infants with intestinal failure

DEFF Research Database (Denmark)

Sigalet, David L; Brindle, Mary E; Boctor, Dana

2017-01-01

BACKGROUND & AIMS: Glucagon-like peptide 2 (GLP-2) analogues are approved for adults with intestinal failure (IF), but no studies have included infants. This study examined the pharmacokinetics (PK), safety, and nutritional effects of GLP-2 in infants with IF. METHODS: With parental consent (Health...

Intravenous glucagon-like peptide 1 normalizes blood glucose after major surgery in patients with type 2 diabetes

DEFF Research Database (Denmark)

Meier, Juris J; Weyhe, Dirk; Michaely, Mark

2004-01-01

of GLP-1 (1.2 pmol x kg x min) and placebo over 8 hrs, each administered in randomized order in the fasting state. C-reactive protein concentrations of 4.9+/-4.2 mg/dL indicated a systemic inflammation. Blood was drawn in 30-min intervals for glucose (glucose oxidase), insulin, C-peptide, glucagon...... practicability and the risk of hypoglycemia. Therefore, the glucose-lowering effect of the incretin hormone glucagon-like peptide 1 (GLP-1) was investigated in patients with type 2 diabetes after major surgery. DESIGN: Randomised clinical study. SETTING: A surgical unit of a university hospital. PATIENTS......, and GLP-1 (specific immunoassays). Statistics were done with repeated-measures analysis of variance and Duncan's post hoc tests. MAIN RESULTS: During the intravenous infusion of GLP-1, plasma glucose concentrations were significantly lowered, reaching the normoglycemic fasting glucose range within 150...

The Degradome database: mammalian proteases and diseases of proteolysis.

Science.gov (United States)

Quesada, Víctor; Ordóñez, Gonzalo R; Sánchez, Luis M; Puente, Xose S; López-Otín, Carlos

2009-01-01

The degradome is defined as the complete set of proteases present in an organism. The recent availability of whole genomic sequences from multiple organisms has led us to predict the contents of the degradomes of several mammalian species. To ensure the fidelity of these predictions, our methods have included manual curation of individual sequences and, when necessary, direct cloning and sequencing experiments. The results of these studies in human, chimpanzee, mouse and rat have been incorporated into the Degradome database, which can be accessed through a web interface at http://degradome.uniovi.es. The annotations about each individual protease can be retrieved by browsing catalytic classes and families or by searching specific terms. This web site also provides detailed information about genetic diseases of proteolysis, a growing field of great importance for multiple users. Finally, the user can find additional information about protease structures, protease inhibitors, ancillary domains of proteases and differences between mammalian degradomes.

The exaggerated glucagon-like peptide-1 response is important for the improved β-cell function and glucose tolerance after Roux-en-Y gastric bypass in patients with type 2 diabetes

DEFF Research Database (Denmark)

Jørgensen, Nils B; Dirksen, Carsten; Bojsen-Møller, Kirstine N

2013-01-01

β-cell function is improved in patients with type 2 diabetes in response to an oral glucose stimulus after Roux-en-Y gastric bypass (RYGB) surgery. This has been linked to an exaggerated glucagon-like peptide 1 (GLP-1) secretion, but causality has not been established. The aim of this study...... consisted of two experimental days, allowing a meal test with infusion of saline or Ex-9 in random order. After RYGB, glucose tolerance improved, β-cell glucose sensitivity (β-GS) doubled, the GLP-1 response greatly increased and glucagon secretion was augmented. GLP-1R blockade did not affect β......-cell function and meal-induced glucagon release before the operation, but did impair glucose tolerance. After RYGB, β-GS decreased to preoperative levels, glucagon secretion increased and glucose tolerance was impaired by Ex-9 infusion. Thus, the exaggerated effect of GLP-1 after RYGB is of major importance...

Intestinal permeability and glucagon-like peptide-2 in children with autism

DEFF Research Database (Denmark)

Robertson, Marli A; Sigalet, David L; Holst, Jens Juul

2008-01-01

We measured small intestinal permeability using a lactulose:mannitol sugar permeability test in a group of children with autism, with current or previous gastrointestinal complaints. Secondly, we examined whether children with autism had an abnormal glucagon-like peptide-2 (GLP-2) response...... to feeding. Results were compared with sibling controls and children without developmental disabilities. We enrolled 14 children with autism, 7 developmentally normal siblings of these children and 8 healthy, developmentally normal, unrelated children. Our study did not detect differences in these measures...... of gastrointestinal function in a group of children with autism....

Synaptotagmin-7 is a principal Ca2+ sensor for Ca2+ -induced glucagon exocytosis in pancreas

DEFF Research Database (Denmark)

Gustavsson, Natalia; Wei, Shun-Hui; Hoang, Dong Nhut

2009-01-01

Hormones such as glucagon are secreted by Ca(2+)-induced exocytosis of large dense-core vesicles, but the mechanisms involved have only been partially elucidated. Studies of pancreatic beta-cells secreting insulin revealed that synaptotagmin-7 alone is not sufficient to mediate Ca(2+)-dependent i...

Changes in yogurt fermentation characteristics, and antioxidant potential and in vitro inhibition of angiotensin-1 converting enzyme upon the inclusion of peppermint, dill and basil

OpenAIRE

Amirdivani, Shabboo

2011-01-01

The present study investigated the effects of peppermint (Mentha piperita), dill (Anethum graveolens) and basil (Ocimum basilicum) on yogurt formation, proteolysis and inhibition of angiotensin-1 converting enzyme (ACE). Herbal-yogurts had faster rates of pH reduction than plain-yogurt. All herbal-yogurts had higher (p < 0.05) antioxidant activities than plain-yogurt, both at the end of fermentation and throughout the storage period. The o-phthalaldehyde (OPA) peptides in herbal-yogurts in...

Calpain-mediated proteolysis of tropomodulin isoforms leads to thin filament elongation in dystrophic skeletal muscle.

Science.gov (United States)

Gokhin, David S; Tierney, Matthew T; Sui, Zhenhua; Sacco, Alessandra; Fowler, Velia M

2014-03-01

Duchenne muscular dystrophy (DMD) induces sarcolemmal mechanical instability and rupture, hyperactivity of intracellular calpains, and proteolytic breakdown of muscle structural proteins. Here we identify the two sarcomeric tropomodulin (Tmod) isoforms, Tmod1 and Tmod4, as novel proteolytic targets of m-calpain, with Tmod1 exhibiting ∼10-fold greater sensitivity to calpain-mediated cleavage than Tmod4 in situ. In mdx mice, increased m-calpain levels in dystrophic soleus muscle are associated with loss of Tmod1 from the thin filament pointed ends, resulting in ∼11% increase in thin filament lengths. In mdx/mTR mice, a more severe model of DMD, Tmod1 disappears from the thin filament pointed ends in both tibialis anterior (TA) and soleus muscles, whereas Tmod4 additionally disappears from soleus muscle, resulting in thin filament length increases of ∼10 and ∼12% in TA and soleus muscles, respectively. In both mdx and mdx/mTR mice, both TA and soleus muscles exhibit normal localization of α-actinin, the nebulin M1M2M3 domain, Tmod3, and cytoplasmic γ-actin, indicating that m-calpain does not cause wholesale proteolysis of other sarcomeric and actin cytoskeletal proteins in dystrophic skeletal muscle. These results implicate Tmod proteolysis and resultant thin filament length misspecification as novel mechanisms that may contribute to DMD pathology, affecting muscles in a use- and disease severity-dependent manner.

Human monoclonal antibodies against glucagon receptor improve glucose homeostasis by suppression of hepatic glucose output in diet-induced obese mice.

Directory of Open Access Journals (Sweden)

Wook-Dong Kim

Full Text Available AIM: Glucagon is an essential regulator of hepatic glucose production (HGP, which provides an alternative therapeutic target for managing type 2 diabetes with glucagon antagonists. We studied the effect of a novel human monoclonal antibody against glucagon receptor (GCGR, NPB112, on glucose homeostasis in diet-induced obese (DIO mice. METHODS: The glucose-lowering efficacy and safety of NPB112 were investigated in DIO mice with human GCGR for 11 weeks, and a hyperinsulinemic-euglycemic clamp study was conducted to measure HGP. RESULTS: Single intraperitoneal injection of NPB112 with 5 mg/kg effectively decreased blood glucose levels in DIO mice for 5 days. A significant reduction in blood glucose was observed in DIO mice treated with NPB112 at a dose ≥5 mg/kg for 6 weeks, and its glucose-lowering effect was dose-dependent. Long-term administration of NPB112 also caused a mild 29% elevation in glucagon level, which was returned to the normal range after discontinuation of treatment. The clamp study showed that DIO mice injected with NPB112 at 5 mg/kg were more insulin sensitive than control mice, indicating amelioration of insulin resistance by treatment with NPB112. DIO mice treated with NPB112 showed a significant improvement in the ability of insulin to suppress HGP, showing a 33% suppression (from 8.3 mg/kg/min to 5.6 mg/kg/min compared to the 2% suppression (from 9.8 mg/kg/min to 9.6 mg/kg/min in control mice. In addition, no hypoglycemia or adverse effect was observed during the treatment. CONCLUSIONS: A novel human monoclonal GCGR antibody, NPB112, effectively lowered the glucose level in diabetic animal models with mild and reversible hyperglucagonemia. Suppression of excess HGP with NPB112 may be a promising therapeutic modality for the treatment of type 2 diabetes.

Oxyntomodulin differentially affects glucagon-like peptide-1 receptor beta-arrestin recruitment and signaling through Galpha(s)

DEFF Research Database (Denmark)

Jorgensen, Rasmus; Kubale, Valentina; Vrecl, Milka

2007-01-01

The glucagon-like peptide (GLP)-1 receptor is a promising target for the treatment of type 2 diabetes and obesity, and there is great interest in characterizing the pharmacology of the GLP-1 receptor and its ligands. In the present report, we have applied bioluminescence resonance energy transfer...

Involvement of endogenous glucagon-like peptide-1 in regulation of gastric motility and pancreatic endocrine secretion

DEFF Research Database (Denmark)

Witte, Anne-Barbara; Grybäck, Per; Jacobsson, Hans

2011-01-01

Objective. To study the role of endogenous glucagon-like peptide-1 (GLP-1) on gastric emptying rates of a solid meal as well as postprandial hormone secretion and glucose disposal. Material and methods. In nine healthy subjects, gastric emptying of a 310-kcal radio-labelled solid meal and plasma ...

Regulation of progranulin expression in human microglia and proteolysis of progranulin by matrix metalloproteinase-12 (MMP-12.

Directory of Open Access Journals (Sweden)

Hyeon-Sook Suh

Full Text Available The essential role of progranulin (PGRN as a neurotrophic factor has been demonstrated by the discovery that haploinsufficiency due to GRN gene mutations causes frontotemporal lobar dementia. In addition to neurons, microglia in vivo express PGRN, but little is known about the regulation of PGRN expression by microglia.In the current study, we examined the regulation of expression and function of PGRN, its proteolytic enzyme macrophage elastase (MMP-12, as well as the inhibitor of PGRN proteolysis, secretory leukocyte protease inhibitor (SLPI, in human CNS cells.Cultures of primary human microglia and astrocytes were stimulated with the TLR ligands (LPS or poly IC, Th1 cytokines (IL-1/IFNγ, or Th2 cytokines (IL-4, IL-13. Results were analyzed by Q-PCR, immunoblotting or ELISA. The roles of MMP-12 and SLPI in PGRN cleavage were also examined.Unstimulated microglia produced nanogram levels of PGRN, and PGRN release from microglia was suppressed by the TLR ligands or IL-1/IFNγ, but increased by IL-4 or IL-13. Unexpectedly, while astrocytes stimulated with proinflammatory factors released large amounts of SLPI, none were detected in microglial cultures. We also identified MMP-12 as a PGRN proteolytic enzyme, and SLPI as an inhibitor of MMP-12-induced PGRN proteolysis. Experiments employing PGRN siRNA demonstrated that microglial PGRN was involved in the cytokine and chemokine production following TLR3/4 activation, with its effect on TNFα being the most conspicuous.Our study is the first detailed examination of PGRN in human microglia. Our results establish microglia as a significant source of PGRN, and MMP-12 and SLPI as modulators of PGRN proteolysis. Negative and positive regulation of microglial PGRN release by the proinflammatory/Th1 and the Th2 stimuli, respectively, suggests a fundamentally different aspect of PGRN regulation compared to other known microglial activation products. Microglial PGRN appears to function as an endogenous

Proghrelin-derived peptides influence the secretion of insulin, glucagon, pancreatic polypeptide and somatostatin: a study on isolated islets from mouse and rat pancreas

DEFF Research Database (Denmark)

Qader, S.S.; Hakanson, R.; Lundquist, I.

2008-01-01

ghrelin, and to the 23-amino acid peptide obestatin, claimed to be a physiological opponent of acyl ghrelin. This study examines the effects of the proghrelin products, alone and in combinations, on the secretion of insulin, glucagon, pancreatic polypeptide (PP) and somatostatin from isolated islets...... times higher concentration than acyl ghrelin (corresponding to the ratio of the two peptides in circulation), desacyl ghrelin abolished the effects of acyl ghrelin but not those of obestatin. Acyl ghrelin and obestatin affected the secretion of glucagon, PP and somatostatin at physiologically relevant...

The Vildagliptin Experience - 25 Years Since the Initiation of the Novartis Glucagon-like Peptide-1 Based Therapy Programme and 10 Years Since the First Vildagliptin Registration.

Science.gov (United States)

Foley, James E; Ahrén, Bo

2017-08-01

The discovery of the incretin hormone glucagon like peptide-1 (GLP-1), and its usefulness in the treatment of type 2 diabetes mellitus (T2DM) followed by the finding that dipeptidyl peptidase-4 (DPP-4) inhibition prevents GLP-1 inactivation, led to the discovery of DPP-728. In 1999, studies with DPP-728 established the first proof-of-concept that DPP-4 inhibition improves glycaemic control in patients with T2DM. Further efforts to improve the binding kinetics of DPP-728 resulted in the discovery of vildagliptin (LAF237). In the last 20 years, a plethora of studies conducted by Novartis in collaboration with external investigators has demonstrated the mechanism of action of vildagliptin and its efficacy as monotherapy and as an add-on therapy for patients with T2DM. The studies establish that vildagliptin is a selective DPP-4 inhibitor that blocks GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) inactivation, thereby prolonging their action, resulting in improved glycaemic control. This review aims to discuss the discovery and development of vildagliptin, with an emphasis on mechanism of action and clinical efficacy.

Inappropriate suppression of glucagon during OGTT but not during isoglycaemic i.v. glucose infusion contributes to the reduced incretin effect in type 2 diabetes mellitus

DEFF Research Database (Denmark)

Knop, F K; Vilsbøll, T; Madsbad, S

2007-01-01

AIMS/HYPOTHESIS: We investigated glucagon responses during OGTT and isoglycaemic i.v. glucose infusion, respectively, to further elucidate the mechanisms behind the glucose intolerance in patients with type 2 diabetes. MATERIALS AND METHODS: Ten patients (eight men) with type 2 diabetes (age: 64...... during the 2 days was obtained in both groups. In the control subjects no difference in glucagon suppression during the first 45 min of OGTT and isoglycaemic i.v. glucose infusion (-36 +/- 12 vs -64 +/- 23 mmol/l x 45 min; p = NS) was observed, whereas in the group of patients with type 2 diabetes...... significant glucagon suppression only occurred following isoglycaemic i.v. glucose infusion (-63 +/- 21 vs 10 +/- 16 mmol/l x 45 min; p = 0.002). The incretin effect was significantly reduced in patients with type 2 diabetes compared with control subjects, but no significant differences in the secretion...

Time-Course of Muscle Mass Loss, Damage, and Proteolysis in Gastrocnemius following Unloading and Reloading: Implications in Chronic Diseases

Science.gov (United States)

Chacon-Cabrera, Alba; Lund-Palau, Helena; Gea, Joaquim; Barreiro, Esther

2016-01-01

Background Disuse muscle atrophy is a major comorbidity in patients with chronic diseases including cancer. We sought to explore the kinetics of molecular mechanisms shown to be involved in muscle mass loss throughout time in a mouse model of disuse muscle atrophy and recovery following immobilization. Methods Body and muscle weights, grip strength, muscle phenotype (fiber type composition and morphometry and muscle structural alterations), proteolysis, contractile proteins, systemic troponin I, and mitochondrial content were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15 and 30 days) of non-invasive hindlimb immobilization (plastic splint, I cohorts) and in those exposed to reloading for different time-points (1, 3, 7, 15, and 30 days, R cohorts) following a seven-day period of immobilization. Groups of control animals were also used. Results Compared to non-exposed controls, muscle weight, limb strength, slow- and fast-twitch cross-sectional areas, mtDNA/nDNA, and myosin content were decreased in mice of I cohorts, whereas tyrosine release, ubiquitin-proteasome activity, muscle injury and systemic troponin I levels were increased. Gastrocnemius reloading following splint removal improved muscle mass loss, strength, fiber atrophy, injury, myosin content, and mtDNA/nDNA, while reducing ubiquitin-proteasome activity and proteolysis. Conclusions A consistent program of molecular and cellular events leading to reduced gastrocnemius muscle mass and mitochondrial content and reduced strength, enhanced proteolysis, and injury, was seen in this non-invasive mouse model of disuse muscle atrophy. Unloading of the muscle following removal of the splint significantly improved the alterations seen during unloading, characterized by a specific kinetic profile of molecular events involved in muscle regeneration. These findings have implications in patients with chronic diseases including cancer in whom physical activity may be severely compromised. PMID

The Vip3Ag4 Insecticidal Protoxin from Bacillus thuringiensis Adopts A Tetrameric Configuration That Is Maintained on Proteolysis

Directory of Open Access Journals (Sweden)

Leopoldo Palma

2017-05-01

Full Text Available The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy. Sites sensitive to proteolysis by trypsin are identified and the trypsin-cleaved protein appears to retain a similar structure as an octomeric complex comprising four copies each of the ~65 kDa and ~21 kDa products of proteolysis. This processed form of the toxin may represent the active toxin. The quality and monodispersity of the protein produced in this study make Vip3Ag4 a candidate for more detailed structural analysis using cryo-electron microscopy.

Glucagon-like peptide-1 receptor agonists and risk of acute pancreatitis in patients with type 2 diabetes

DEFF Research Database (Denmark)

Storgaard, Heidi; Cold, Frederik; Gluud, Lise L

2017-01-01

Glucagon-like peptide-1 receptor agonist (GLP-1RAs) labels warn about acute pancreatitis (AP) and impose upon doctors the obligation to inform patients about symptoms of AP. Here we systematically reviewed the risk of AP in randomized placebo-controlled trials (RCTs) investigating the effect of GLP...

Exendin-4, but not glucagon-like peptide-1, is cleared exclusively by glomerular filtration in anaesthetised pigs

DEFF Research Database (Denmark)

Simonsen, L; Holst, Jens Juul; Deacon, C F

2006-01-01

AIMS/HYPOTHESIS: The insulinotropic hormone, glucagon-like peptide-1 (GLP-1), is rapidly degraded in vivo as a result of the combination of extensive enzymatic degradation and renal extraction. The GLP-1 receptor agonist, exendin-4, has a longer duration of action, and has recently been approved ...

Glucagon-like peptide 2 improves nutrient absorption and nutritional status in short-bowel patients with no colon

DEFF Research Database (Denmark)

Jeppesen, P B; Hartmann, B; Thulesen, J

2001-01-01

Glucagon-like peptide 2 (GLP-2) is intestinotrophic, antisecretory, and transit-modulating in rodents, and it is mainly secreted from the intestinal mucosa of the terminal ileum and colon after food ingestion. We assessed the effect of GLP-2 on the gastrointestinal function in patients without a ...

Effect of pulsed electric field on the proteolysis of cold boned beef M. Longissimus lumborum and M. Semimembranosus.

Science.gov (United States)

Suwandy, Via; Carne, Alan; van de Ven, Remy; Bekhit, Alaa El-Din A; Hopkins, David L

2015-02-01

The effects of pulsed electric field (PEF) and ageing (3, 7, 14 and 21 days) on the shear force, protein profile, and post-mortem proteolysis of beef loins (M. Longissimus lumborum, LL) and topsides (M. Semimembranosus, SM) were investigated using a range of pulsed electric field treatments [voltages (5 and 10 kV) and frequencies (20, 50, and 90 Hz)]. PEF treatment decreased the shear force of beef LL and SM muscles by up to 19%. The reduction in the shear force in the LL was not affected by the treatment intensity whereas the reduction in the SM was dependent on PEF frequency. PEF treated beef loins showed increased proteolysis, both early post-mortem and during subsequent post-mortem storage reflected by increased degradation of troponin-T and desmin. The most prominent troponin-T degradation was found in samples treated with 5 kV-90 Hz, 10 kV-20 Hz at day 3 and day 7 post-treatment in addition to 10 kV-50 Hz in subsequent post-treatment times. The degradation of desmin in PEF treated beef loins increased with ageing time.

Glucagon-like peptide 1 (7-36) amide stimulates exocytosis in human pancreatic beta-cells by both proximal and distal regulatory steps in stimulus-secretion coupling

DEFF Research Database (Denmark)

Gromada, J; Bokvist, K; Ding, W G

1998-01-01

The effect of glucagon-like peptide 1(7-36) amide [GLP-1(7-36) amide] on membrane potential, whole-cell ATP-sensitive potassium channel (K[ATP]) and Ca2+ currents, cytoplasmic Ca2+ concentration, and exocytosis was explored in single human beta-cells. GLP-1(7-36) amide induced membrane...... depolarization that was associated with inhibition of whole-cell K(ATP) current. In addition, GLP-1(7-36) amide (and forskolin) produced greater than fourfold potentiation of Ca2+-dependent exocytosis. The latter effect resulted in part (40%) from acceleration of Ca2+ influx through voltage-dependent (L-type) Ca......2+ channels. More importantly, GLP-1(7-36) amide (via generation of cyclic AMP and activation of protein kinase A) potentiated exocytosis at a site distal to a rise in the cytoplasmic Ca2+ concentration. Photorelease of caged cAMP produced a two- to threefold potentiation of exocytosis when...

Effects of gender, body weight, and blood glucose dynamics on the growth hormone response to the glucagon stimulation test in patients with pituitary disease.

Science.gov (United States)

Wilson, Jessica R; Utz, Andrea L; Devin, Jessica K

2016-02-01

Body weight blunts the growth hormone (GH) response to provocative stimuli. The appropriate GH cut-off to confirm GH deficiency in obese and overweight patients undergoing the glucagon stimulation test (GST) has recently been questioned. We hypothesized that the peak GH would be inversely related to the nadir blood glucose (BG) after glucagon and that this may be a mechanism influencing peak GH in overweight patients. This retrospective study examined effects of gender, body weight, and BG dynamics on GH response to GST in patients evaluated in our Pituitary Center. Adult patients who underwent GST from September 2009-2014 were included. Continuous variable comparisons were analyzed using the Mann-Whitney U-test and categorical data by Fisher's Exact Test. Spearman correlation was used to determine associations between continuous variables. 42 patients (N=28, 66.7% female) had sufficient data for analysis. Obese patients (N=26) had a reduced GH response, summarized as GH area under the curve (AUC) (p=0.03 vs. non-obese patients) and higher BG during GST, summarized as AUC (pAUC (rs=-0.45; p=0.01), peak GH response (rs=-0.42; p=0.02) and nadir BG (rs=0.48; pAUC (rs=-0.38; p=0.03) and peak GH (rs=-0.37; p=0.04) such that patients (N=32) with higher nadir BG had lower peak GH in response to glucagon. Obese patients, particularly women, do not respond as robustly to glucagon stimulation. These data suggest that there exists an altered BG profile during GST in obese individuals, and that a less robust hypoglycemic stimulus may contribute to an impaired GH response. We suggest measuring BG levels during glucagon stimulation testing to assist with clinical interpretation of GH dynamics. The diagnostic accuracy of the GST in patients with known disorders in glucose metabolism and those taking anti-diabetic medications deserves further study. Copyright © 2015 Elsevier Ltd. All rights reserved.

Histopathological growth pattern, proteolysis and angiogenesis in chemonaive patients resected for multiple colorectal liver metastases

DEFF Research Database (Denmark)

Eefsen, Rikke Løvendahl; Van den Eynden, Gert G; Høyer-Hansen, Gunilla

2012-01-01

The purpose of this study was to characterise growth patterns, proteolysis, and angiogenesis in colorectal liver metastases from chemonaive patients with multiple liver metastases. Twenty-four patients were included in the study, resected for a median of 2.6 metastases. The growth pattern......-type plasminogen activator receptor (P = 0.0008). Angiogenesis was most pronounced in metastases with a pushing growth pattern in comparison to those with desmoplastic (P = 0.0007) and replacement growth pattern (P = 0.021). Although a minor fraction of the patients harboured metastases with different growth...

Glucose-induced glucagon-like Peptide 1 secretion is deficient in patients with non-alcoholic fatty liver disease.

Directory of Open Access Journals (Sweden)

Christine Bernsmeier

Full Text Available The incretins glucagon-like peptide-1 (GLP-1 and glucose-dependent insulinotropic polypeptide (GIP are gastrointestinal peptide hormones regulating postprandial insulin release from pancreatic β-cells. GLP-1 agonism is a treatment strategy in Type 2 diabetes and is evaluated in Non-alcoholic fatty liver disease (NAFLD. However, the role of incretins in its pathophysiology is insufficiently understood. Studies in mice suggest improvement of hepatic steatosis by GLP-1 agonism. We determined the secretion of incretins after oral glucose administration in non-diabetic NAFLD patients.N=52 patients (n=16 NAFLD and n=36 Non-alcoholic steatohepatitis (NASH patients and n=50 matched healthy controls were included. Standardized oral glucose tolerance test was performed. Glucose, insulin, glucagon, GLP-1 and GIP plasma levels were measured sequentially for 120 minutes after glucose administration.Glucose induced GLP-1 secretion was significantly decreased in patients compared to controls (p<0.001. In contrast, GIP secretion was unchanged. There was no difference in GLP-1 and GIP secretion between NAFLD and NASH subgroups. All patients were insulin resistant, however HOMA2-IR was highest in the NASH subgroup. Fasting and glucose-induced insulin secretion was higher in NAFLD and NASH compared to controls, while the glucose lowering effect was diminished. Concomitantly, fasting glucagon secretion was significantly elevated in NAFLD and NASH.Glucose-induced GLP-1 secretion is deficient in patients with NAFLD and NASH. GIP secretion is contrarily preserved. Insulin resistance, with hyperinsulinemia and hyperglucagonemia, is present in all patients, and is more severe in NASH compared to NAFLD. These pathophysiologic findings endorse the current evaluation of GLP-1 agonism for the treatment of NAFLD.

Comparison of a carbohydrate-free diet vs. fasting on plasma glucose, insulin and glucagon in type 2 diabetes.

Science.gov (United States)

Nuttall, Frank Q; Almokayyad, Rami M; Gannon, Mary C

2015-02-01

Hyperglycemia improves when patients with type 2 diabetes are placed on a weight-loss diet. Improvement typically occurs soon after diet implementation. This rapid response could result from low fuel supply (calories), lower carbohydrate content of the weight-loss diet, and/or weight loss per se. To differentiate these effects, glucose, insulin, C-peptide and glucagon were determined during the last 24 h of a 3-day period without food (severe calorie restriction) and a calorie-sufficient, carbohydrate-free diet. Seven subjects with untreated type 2 diabetes were studied. A randomized-crossover design with a 4-week washout period between arms was used. Results from both the calorie-sufficient, carbohydrate-free diet and the 3-day fast were compared with the initial standard diet consisting of 55% carbohydrate, 15% protein and 30% fat. The overnight fasting glucose concentration decreased from 196 (standard diet) to 160 (carbohydrate-free diet) to 127 mg/dl (fasting). The 24 h glucose and insulin area responses decreased by 35% and 48% on day 3 of the carbohydrate-free diet, and by 49% and 69% after fasting. Overnight basal insulin and glucagon remained unchanged. Short-term fasting dramatically lowered overnight fasting and 24 h integrated glucose concentrations. Carbohydrate restriction per se could account for 71% of the reduction. Insulin could not entirely explain the glucose responses. In the absence of carbohydrate, the net insulin response was 28% of the standard diet. Glucagon did not contribute to the metabolic adaptations observed. Published by Elsevier Inc.

Glucagon suppression during OGTT worsens while suppression during IVGTT sustains alongside development of glucose intolerance in patients with chronic pancreatitis

DEFF Research Database (Denmark)

Knop, F K; Vilsbøll, T; Larsen, Steen

2010-01-01

To examine plasma glucagon responses to oral and intravenous (iv) glucose in patients with chronic pancreatitis (CP) and either normal glucose tolerance (NGT), secondary impaired glucose tolerance (IGT) or secondary diabetes mellitus (DM)....

Pancreatic beta-cell overexpression of the glucagon receptor gene results in enhanced beta-cell function and mass

DEFF Research Database (Denmark)

Gelling, Richard W; Vuguin, Patricia M; Du, Xiu Quan

2009-01-01

in vivo, we generated mice overexpressing the Gcgr specifically on pancreatic beta-cells (RIP-Gcgr). In vivo and in vitro insulin secretion in response to glucagon and glucose was increased 1.7- to 3.9-fold in RIP-Gcgr mice compared with controls. Consistent with the observed increase in insulin release...

Co-culture of clonal beta cells with GLP-1 and glucagon-secreting cell line impacts on beta cell insulin secretion, proliferation and susceptibility to cytotoxins.

Science.gov (United States)

Green, Alastair D; Vasu, Srividya; Moffett, R Charlotte; Flatt, Peter R

2016-06-01

We investigated the direct effects on insulin releasing MIN6 cells of chronic exposure to GLP-1, glucagon or a combination of both peptides secreted from GLUTag L-cell and αTC1.9 alpha-cell lines in co-culture. MIN6, GLUTag and αTC1.9 cell lines exhibited high cellular hormone content and release of insulin, GLP-1 and glucagon, respectively. Co-culture of MIN6 cells with GLUTag cells significantly increased cellular insulin content, beta-cell proliferation, insulin secretory responses to a range of established secretogogues and afforded protection against exposure cytotoxic concentrations of glucose, lipid, streptozotocin or cytokines. Benefits of co-culture of MIN6 cells with αTC1.9 alphacells were limited to enhanced beta-cell proliferation with marginal positive actions on both insulin secretion and cellular protection. In contrast, co-culture of MIN6 with GLUTag cells plus αTC1.9 cells, markedly enhanced both insulin secretory responses and protection against beta-cell toxins compared with co-culture with GLUTag cells alone. These data indicate important long-term effects of conjoint GLP-1 and glucagon exposure on beta-cell function. This illustrates the possible functional significance of alpha-cell GLP-1 production as well as direct beneficial effects of dual agonism at beta-cell GLP-1 and glucagon receptors. Copyright © 2016 Elsevier B.V. and Société française de biochimie et biologie Moléculaire (SFBBM). All rights reserved.

Glucagon-Like Peptide 1 Prevents Reactive Oxygen Species-Induced Endothelial Cell Senescence Through the Activation of Protein Kinase A

NARCIS (Netherlands)

Oeseburg, Hisko; de Boer, Rudolf A.; Buikema, Hendrik; van der Harst, Pim; van Gilst, Wiek H.; Sillje, Herman H. W.

Objective-Endothelial cell senescence is an important contributor to vascular aging and is increased under diabetic conditions. Here we investigated whether the antidiabetic hormone glucagon-like peptide 1 (GLP-1) could prevent oxidative stress-induced cellular senescence in endothelial cells.

Exogenous glucagon-like peptide-2 (GLP-2) augments GLP-2 receptor mRNA and maintains proglucagon mRNA levels in resected rats

DEFF Research Database (Denmark)

Koopmann, Matthew C; Nelson, David W; Murali, Sangita G

2008-01-01

BACKGROUND: Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent proglucagon-derived hormone that stimulates intestinal adaptive growth. Our aim was to determine whether exogenous GLP-2 increases resection-induced adaptation without diminishing endogenous proglucagon and GLP-2 receptor express...... augments adaptive growth and digestive capacity of the residual small intestine in a rat model of mid-small bowel resection by increasing plasma GLP-2 concentrations and GLP-2 receptor expression without diminishing endogenous proglucagon expression.......BACKGROUND: Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent proglucagon-derived hormone that stimulates intestinal adaptive growth. Our aim was to determine whether exogenous GLP-2 increases resection-induced adaptation without diminishing endogenous proglucagon and GLP-2 receptor...

Determinants of the effectiveness of glucagon-like peptide-1 in type 2 diabetes

DEFF Research Database (Denmark)

Toft-Nielsen, M B; Madsbad, Sten; Holst, J J

2001-01-01

.0003). Nonresponders were not identified. Multiple regression analysis with Kg or Nadir plasma glucose as the dependent parameter and body mass index, age, gender, diabetes duration, and significantly correlated parameters (in multiple regression for Kg: fasting plasma glucose, fasting nonesterified fatty acid......, dipeptidyl peptidase activity, peak insulin, and the logarithm of beta-cell function; and for Nadir plasma glucose: fasting plasma glucose, fasting nonesterified fatty acid, dipeptidyl peptidase activity, delta glucagon decrement, F-GLP-1 total, logarithm of beta-cell function, and Kg) as independent...

Inhibition of proteases and phospholipases A2 from Bothrops atrox and Crotalus durissus terrificus snake venoms by ascorbic acid, vitamin E, and B-complex vitamins.

Science.gov (United States)

Oliveira, Carlos H M; Simão, Anderson A; Trento, Marcus V C; César, Pedro H S; Marcussi, Silvana

2016-01-01

The enzyme inhibition by natural and/ or low-cost compounds may represent a valuable adjunct to traditional serotherapy performed in cases of snakebite, mainly with a view to mitigate the local effects of envenoming. The objective of this study was to evaluate possible interactions between vitamins and enzymes that comprise Bothrops atrox and Crotalus durissus terrificus venoms, in vitro. Proteolysis inhibition assays (substrates: azocasein, collagen, gelatin and fibrinogen), hemolysis, coagulation, hemagglutination were carried out using different proportions of vitamins in face of to inhibit minimum effective dose of each venom. The vitamins were responsible for reducing 100% of breaking azocasein by C.d.t. venom, thrombolysis induced by B. atrox and fibrinogenolysis induced by both venoms. It is suggested the presence of interactions between vitamin and the active site of enzymes, for example the interactions between hydrophobic regions present in the enzymes and vitamin E, as well as the inhibitions exercised by antioxidant mechanism.

Comparison Review of Short-Acting and Long-Acting Glucagon-like Peptide-1 Receptor Agonists

OpenAIRE

Uccellatore, Annachiara; Genovese, Stefano; Dicembrini, Ilaria; Mannucci, Edoardo; Ceriello, Antonio

2015-01-01

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) are useful tools for treating type 2 diabetes mellitus. In their recent position statement, the American Diabetes Association and European Association for the Study of Diabetes recommend GLP1-RAs as add-on to metformin when therapeutic goals are not achieved with monotherapy, particularly for patients who wish to avoid weight gain or hypoglycemia. GLP1-RAs differ substantially in their duration of action, frequency of administratio...

Real-time trafficking and signaling of the glucagon-like peptide-1 receptor

DEFF Research Database (Denmark)

Roed, Sarah Noerklit; Wismann, Pernille; Underwood, Christina Rye

2014-01-01

The glucagon-like peptide-1 incretin receptor (GLP-1R) of family B G protein-coupled receptors (GPCRs) is a major drug target in type-2-diabetes due to its regulatory effect on post-prandial blood-glucose levels. The mechanism(s) controlling GLP-1R mediated signaling are far from fully understood....... A fundamental mechanism controlling the signaling capacity of GPCRs is the post-endocytic trafficking of receptors between recycling and degradative fates. Here, we combined microscopy with novel real-time assays to monitor both receptor trafficking and signaling in living cells. We find that the human GLP-1R...

Effect of glucagon-like peptide-1 (proglucagon 78-107amide) on hepatic glucose production in healthy man

DEFF Research Database (Denmark)

Hvidberg, A; Nielsen, M T; Hilsted, J

1994-01-01

at rates of 25 and 75 pmol.kg-1.h-1 into eight healthy volunteers after an overnight fast and measured plasma concentrations of glucose, insulin, and glucagon and glucose turnover by a technique involving infusion of 3-3H-glucose. Plasma levels of GLP-1 increased by 21.3 +/- 3.1 and 75.4 +/- 3.2 pmol....../L during the infusion, changes that were within physiologic limits. In a control experiment only saline was infused. During GLP-1 infusion, plasma glucose level decreased significantly (from 5.3 +/- 0.1 to 4.7 +/- 0.1 and 4.3 +/- 0.1 pmol/L at the end of the two infusion periods). Despite this, plasma...... insulin level increased significantly (from 20.5 +/- 2.9 to a peak value of 33.5 +/- 5.2 pmol/L during the second period), and plasma glucagon level decreased (from 9.3 +/- 1.7 to 7.1 +/- 1.0 pmol/L). Glucose rate of appearance (Ra) decreased significantly to 75% +/- 6% of the preinfusion values during...

Probing the 3-D Structure, Dynamics, and Stability of Bacterial Collagenase Collagen Binding Domain (apo- versus holo-) by Limited Proteolysis MALDI-TOF MS

Science.gov (United States)

Sides, Cynthia R.; Liyanage, Rohana; Lay, Jackson O.; Philominathan, Sagaya Theresa Leena; Matsushita, Osamu; Sakon, Joshua

2012-03-01

Pairing limited proteolysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to probe clostridial collagenase collagen binding domain (CBD) reveals the solution dynamics and stability of the protein, as these factors are crucial to CBD effectiveness as a drug-delivery vehicle. MS analysis of proteolytic digests indicates initial cleavage sites, thereby specifying the less stable and highly accessible regions of CBD. Modulation of protein structure and stability upon metal binding is shown through MS analysis of calcium-bound and cobalt-bound CBD proteolytic digests. Previously determined X-ray crystal structures illustrate that calcium binding induces secondary structure transformation in the highly mobile N-terminal arm and increases protein stability. MS-based detection of exposed residues confirms protein flexibility, accentuates N-terminal dynamics, and demonstrates increased global protein stability exported by calcium binding. Additionally, apo- and calcium-bound CBD proteolysis sites correlate well with crystallographic B-factors, accessibility, and enzyme specificity. MS-observed cleavage sites with no clear correlations are explained either by crystal contacts of the X-ray crystal structures or by observed differences between Molecules A and B in the X-ray crystal structures. The study newly reveals the absence of the βA strand and thus the very dynamic N-terminal linker, as corroborated by the solution X-ray scattering results. Cobalt binding has a regional effect on the solution phase stability of CBD, as limited proteolysis data implies the capture of an intermediate-CBD solution structure when cobalt is bound.

Calpain Inhibition Reduces Axolemmal Leakage in Traumatic Axonal Injury

Directory of Open Access Journals (Sweden)

János Sándor

2009-12-01

Full Text Available Calcium-induced, calpain-mediated proteolysis (CMSP has recently been implicated to the pathogenesis of diffuse (traumatic axonal injury (TAI. Some studies suggested that subaxolemmal CMSP may contribute to axolemmal permeability (AP alterations observed in TAI. Seeking direct evidence for this premise we investigated whether subaxolemmal CMSP may contribute to axolemmal permeability alterations (APA and pre-injury calpain-inhibition could reduce AP in a rat model of TAI. Horseradish peroxidase (HRP, a tracer that accumulates in axons with APA was administered one hour prior to injury into the lateral ventricle; 30 min preinjury a single tail vein bolus injection of 30 mg/kg MDL-28170 (a calpain inhibitor or its vehicle was applied in Wistar rats exposed to impact acceleration brain injury. Histological detection of traumatically injured axonal segments accumulating HRP and statistical analysis revealed that pre-injury administration of the calpain inhibitor MDL-28170 significantly reduced the average length of HRP-labeled axonal segments. The axono-protective effect of pre-injury calpain inhibition recently demonstrated with classical immunohistochemical markers of TAI was further corroborated in this experiment; significant reduction of the length of labeled axons in the drug-treated rats implicate CMSP in the progression of altered AP in TAI.

Administration of a dipeptidyl peptidase IV inhibitor enhances the intestinal adaptation in a mouse model of short bowel syndrome

DEFF Research Database (Denmark)

Okawada, Manabu; Holst, Jens Juul; Teitelbaum, Daniel H

2011-01-01

Glucagon-like peptide-2 induces small intestine mucosal epithelial cell proliferation and may have benefit for patients who suffer from short bowel syndrome. However, glucagon-like peptide-2 is inactivated rapidly in vivo by dipeptidyl peptidase IV. Therefore, we hypothesized that selectively inh...... inhibiting dipeptidyl peptidase IV would prolong the circulating life of glucagon-like peptide-2 and lead to increased intestinal adaptation after development of short bowel syndrome....

Proteolysis of truncated hemolysin A yields a stable dimerization interface

Energy Technology Data Exchange (ETDEWEB)

Novak, Walter R.P.; Bhattacharyya, Basudeb; Grilley, Daniel P.; Weaver, Todd M. (Wabash); (UW)

2017-02-21

Wild-type and variant forms of HpmA265 (truncated hemolysin A) fromProteus mirabilisreveal a right-handed, parallel β-helix capped and flanked by segments of antiparallel β-strands. The low-salt crystal structures form a dimeric structureviathe implementation of on-edge main-chain hydrogen bonds donated by residues 243–263 of adjacent monomers. Surprisingly, in the high-salt structures of two variants, Y134A and Q125A-Y134A, a new dimeric interface is formedviamain-chain hydrogen bonds donated by residues 203–215 of adjacent monomers, and a previously unobserved tetramer is formed. In addition, an eight-stranded antiparallel β-sheet is formed from the flap regions of crystallographically related monomers in the high-salt structures. This new interface is possible owing to additional proteolysis of these variants after Tyr240. The interface formed in the high-salt crystal forms of hemolysin A variants may mimic the on-edge β-strand positioning used in template-assisted hemolytic activity.

Prandial subcutaneous injections of glucagon-like peptide-1 cause weight loss in obese human subjects

DEFF Research Database (Denmark)

Näslund, Erik; King, N; Mansten, S

2004-01-01

Recombinant glucagon-like peptide-1 (7-36)amide (rGLP-1) was recently shown to cause significant weight loss in type 2 diabetics when administered for 6 weeks as a continuous subcutaneous infusion. The mechanisms responsible for the weight loss are not clarified. In the present study, rGLP-1 was ...... as a probable mechanism of action of increased satiety, decreased hunger and, hence, reduced food intake with an ensuing weight loss....

Ketose induced respiratory inhibition in isolated hepatocytes.

Science.gov (United States)

Martínez, P; Carrascosa, J M; Núñez de Castro, I

1987-06-01

The addition of 10 mM fructose or 10 mM tagatose to a suspension of hepatocytes caused respiratory inhibition, whereas no change in oxygen uptake was observed following the addition of glucose. However, incubations in the presence of fructose showed a high, aerobic glycolytic activity. Tagatose is phosphorylated to tagatose 1-phosphate but is not further metabolized by cell free liver extract. Moreover, the addition of fructose to glucagon treated cells also caused the Crabtree-like effect. The concentration of adenine nucleotides and inorganic phosphate (Pi) in the mitochondrial and cytosolic compartments during incubation (time 30 min) was determined by the digitonin fractionation procedure. In the presence of 10 mM fructose or tagatose, the total adenine nucleotide pools decreased by 40%; however, glucose produced no change. The addition of ketoses diminished the asymmetric distribution of extramitochondrial (ATP/ADP)e ratio and intramitochondrial (ATP/ADP)i ratio. At the same time the total mitochondrial Pi fell from 17 mM to 6-7 mM. The mitochondrial membrane potential (-161 mV) in the presence of fructose showed no changes during the 30 min experimental period. An increase in the NADH/NAD+ ratio was observed. These results suggest that in hepatocytes the inhibition of respiration is not necessarily linked with the enhanced aerobic glycolysis, by competition for common substrates.

Glucagon-like peptide-2 (GLP-2) increases net amino acid utilization by the portal-drained viscera of ruminating calves

DEFF Research Database (Denmark)

Taylor-Edwards, C C; Burrin, D G; Kristensen, Niels Bastian

2012-01-01

Glucagon-like peptide-2 (GLP-2) increases small intestinal mass and blood flow in ruminant calves, but its impact on nutrient metabolism across the portal-drained viscera (PDV) and liver is unknown. Eight Holstein calves with catheters in the carotid artery, mesenteric vein, portal vein and hepat...

Inhibition of Vascular c-Jun N-Terminal Kinase 2 Improves Obesity-Induced Endothelial Dysfunction After Roux-en-Y Gastric Bypass.

Science.gov (United States)

Doytcheva, Petia; Bächler, Thomas; Tarasco, Erika; Marzolla, Vincenzo; Engeli, Michael; Pellegrini, Giovanni; Stivala, Simona; Rohrer, Lucia; Tona, Francesco; Camici, Giovanni G; Vanhoutte, Paul M; Matter, Christian M; Lutz, Thomas A; Lüscher, Thomas F; Osto, Elena

2017-11-14

Roux-en-Y gastric bypass (RYGB) reduces obesity-associated comorbidities and cardiovascular mortality. RYGB improves endothelial dysfunction, reducing c-Jun N-terminal kinase (JNK) vascular phosphorylation. JNK activation links obesity with insulin resistance and endothelial dysfunction. Herein, we examined whether JNK1 or JNK2 mediates obesity-induced endothelial dysfunction and if pharmacological JNK inhibition can mimic RYGB vascular benefits. After 7 weeks of a high-fat high-cholesterol diet, obese rats underwent RYGB or sham surgery; sham-operated ad libitum-fed rats received, for 8 days, either the control peptide D-TAT or the JNK peptide inhibitor D-JNKi-1 (20 mg/kg per day subcutaneous). JNK peptide inhibitor D-JNKi-1 treatment improved endothelial vasorelaxation in response to insulin and glucagon-like peptide-1, as observed after RYGB. Obesity increased aortic phosphorylation of JNK2, but not of JNK1. RYGB and JNK peptide inhibitor D-JNKi-1 treatment blunted aortic JNK2 phosphorylation via activation of glucagon-like peptide-1-mediated signaling. The inhibitory phosphorylation of insulin receptor substrate-1 was reduced, whereas the protein kinase B/endothelial NO synthase pathway was increased and oxidative stress was decreased, resulting in improved vascular NO bioavailability. Decreased aortic JNK2 phosphorylation after RYGB rapidly improves obesity-induced endothelial dysfunction. Pharmacological JNK inhibition mimics the endothelial protective effects of RYGB. These findings highlight the therapeutic potential of novel strategies targeting vascular JNK2 against the severe cardiovascular disease associated with obesity. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Glucagon-like peptide 1 and inhibitors of dipeptidyl peptidase IV in the treatment of type 2 diabetes mellitus

DEFF Research Database (Denmark)

Holst, Jens Juul; Deacon, Carolyn F

2004-01-01

Proof-of-concept for the efficacy of a glucagon-like peptide 1 (GLP-1)-based therapy of patients with type 2 diabetes was provided in 2002 by means of prolonged continuous subcutaneous infusion of native GLP-1. Since then, several long-acting analogues of GLP-1, as well as inhibitors of dipeptidyl...

Impact of the TCF7L2 genotype on risk of hypoglycaemia and glucagon secretion during hypoglycaemia

DEFF Research Database (Denmark)

Kristensen, Peter L; Pedersen-Bjergaard, Ulrik; Due-Andersen, Rikke

2016-01-01

hypoglycaemia and a higher frequency of severe hypoglycaemia (SH) in type 1 diabetes (T1DM). MATERIAL AND METHODS: This is a post hoc study of an earlier prospective observational study of SH and four mechanistic studies of physiological responses to hypoglycaemia. 269 patients with T1DM were followed in a one......-year observational study. A log-linear negative binomial model was applied with events of SH as dependent variable and TCF7L2 alleles as explanatory variable. In four experimental studies including 65 people, TCF7L2 genotyping was done and plasma glucagon concentration during experimental hypoglycaemia...... was determined. RESULTS: Incidences of SH were TT 0.54, TC 0.98 and CC 1.01 episodes per patient-year with no significant difference between groups. During experimental hypoglycaemia, the TCF7L2 polymorphism did not influence glucagon secretion. DISCUSSION: Patients with T1DM carrying the T allele of the TCF7L2...

Continuous subcutaneous infusion of glucagon-like peptide 1 lowers plasma glucose and reduces appetite in type 2 diabetic patients

DEFF Research Database (Denmark)

Toft-Nielsen, M B; Madsbad, Sten; Holst, J J

1999-01-01

OBJECTIVE: The gut hormone glucagon-like peptide 1 (GLP-1) has insulinotropic and anorectic effects during intravenous infusion and has been proposed as a new treatment for type 2 diabetes and obesity. The effect of a single subcutaneous injection is brief because of rapid degradation. We therefore......, previously shown to lower blood glucose effectively in type 2 diabetic patients. Fasting plasma glucose (day 2) decreased from 14.1 +/- 0.9 (saline) to 12.2 +/- 0.7 mmol/l (GLP-1), P = 0.009, and 24-h mean plasma glucose decreased from 15.4 +/- 1.0 to 13.0 +/- 1.0 mmol/l, P = 0.0009. Fasting and total area...... under the curve for insulin and C-peptide levels were significantly higher during the GLP-1 administration, whereas glucagon levels were unchanged. Neither triglycerides nor free fatty acids were affected. GLP-1 administration decreased hunger and prospective food intake and increased satiety, whereas...

Glucagon-like peptide-1 analogs against antipsychotic-induced weight gain

DEFF Research Database (Denmark)

Ebdrup, Bjørn H; Knop, Filip K; Ishøy, Pelle L

2012-01-01

between schizophrenia and overweight patients. DISCUSSION: Current interventions against antipsychotic-induced weight gain do not facilitate a substantial and lasting weight loss. GLP-1 analogues used in the treatment of type 2 diabetes are associated with significant and sustained weight loss...... are already compromised in normal weight patients with schizophrenia. Here we outline the current strategies against antipsychotic-induced weight gain, and we describe peripheral and cerebral effects of the gut hormone glucagon-like peptide-1 (GLP-1). Moreover, we account for similarities in brain changes...... in overweight patients. Potential effects of treating schizophrenia patients with antipsychotic-induced weight gain with GLP-1 analogues are discussed. CONCLUSIONS: We propose that adjunctive treatment with GLP-1 analogues may constitute a new avenue to treat and prevent metabolic and cerebral deficiencies...

Discovery, characterization, and clinical development of the glucagon-like peptides

DEFF Research Database (Denmark)

Drucker, Daniel J; Habener, Joel F; Holst, Jens Juul

2017-01-01

that GLP-2 promotes mucosal growth in the intestine is described, and key findings from both preclinical studies and the GLP-2 clinical development program for short bowel syndrome (SBS) are reviewed. Finally, we summarize recent progress in GLP biology, highlighting emerging concepts and scientific......The discovery, characterization, and clinical development of glucagon-like-peptide-1 (GLP-1) spans more than 30 years and includes contributions from multiple investigators, science recognized by the 2017 Harrington Award Prize for Innovation in Medicine. Herein, we provide perspectives...... on the historical events and key experimental findings establishing the biology of GLP-1 as an insulin-stimulating glucoregulatory hormone. Important attributes of GLP-1 action and enteroendocrine science are reviewed, with emphasis on mechanistic advances and clinical proof-of-concept studies. The discovery...

Imaging Proteolysis by Living Human Breast Cancer Cells

Directory of Open Access Journals (Sweden)

Mansoureh Sameni

2000-01-01

Full Text Available Malignant progression is accompanied by degradation of extracellular matrix proteins. Here we describe a novel confocal assay in which we can observe proteolysis by living human breast cancer cells (BT20 and BT549 through the use of quenchedfluorescent protein substrates. Degradation thus was imaged, by confocal optical sectioning, as an accumulation of fluorescent products. With the BT20 cells, fluorescence was localized to pericellular focal areas that coincide with pits in the underlying matrix. In contrast, fluorescence was localized to intracellular vesicles in the BT549 cells, vesicles that also label for lysosomal markers. Neither intracellular nor pericellular fluorescence was observed in the BT549 cells in the presence of cytochalasin B, suggesting that degradation occurred intracellularly and was dependent on endocytic uptake of substrate. In the presence of a cathepsin 13-selective cysteine protease inhibitor, intracellular fluorescence was decreased ~90% and pericellular fluorescence decreased 67% to 96%, depending on the protein substrate. Matrix metallo protease inhibitors reduced pericellular fluorescence ~50%, i.e., comparably to a serine and a broad spectrum cysteine protease inhibitor. Our results suggest that: 1 a proteolytic cascade participates in pericellular digestion of matrix proteins by living human breast cancer cells, and 2 the cysteine protease cathepsin B participates in both pericellular and intracellular digestion of matrix proteins by living human breast cancer cells.

Colon distension, perceived burden and side-effects of CT-colonography for screening using hyoscine butylbromide or glucagon hydrochloride as bowel relaxant

NARCIS (Netherlands)

de Haan, Margriet C.; Boellaard, Thierry N.; Bossuyt, Patrick M.; Stoker, Jaap

2012-01-01

Objective: Compare colonic distension and perceived burden of CT-colonography between participants receiving hyoscine butylbromide (buscopan) and glucagon hydrochloride as bowel relaxant. Materials and methods: Data were collected within a screening trial. Participants received 20 mg buscopan

Acute effects of the Glucagon-Like Peptide 2 analogue, teduglutide, on intestinal adaptation in newborn pigs with short bowel syndrome

DEFF Research Database (Denmark)

Thymann, Thomas; Stoll, Barbara; Mecklenburg, Lars

2014-01-01

Neonatal short bowel syndrome following massive gut resection associates with malabsorption of nutrients. The intestinotrophic factor glucagon-like peptide 2 (GLP-2) improves gut function in adult short bowel patients, but its effect in pediatric patients remains unknown. Our objective was to test...

Recombinant PrPSc shares structural features with brain-derived PrPSc: Insights from limited proteolysis.

Science.gov (United States)

Sevillano, Alejandro M; Fernández-Borges, Natalia; Younas, Neelam; Wang, Fei; R Elezgarai, Saioa; Bravo, Susana; Vázquez-Fernández, Ester; Rosa, Isaac; Eraña, Hasier; Gil, David; Veiga, Sonia; Vidal, Enric; Erickson-Beltran, Melissa L; Guitián, Esteban; Silva, Christopher J; Nonno, Romolo; Ma, Jiyan; Castilla, Joaquín; R Requena, Jesús

2018-01-01

Very solid evidence suggests that the core of full length PrPSc is a 4-rung β-solenoid, and that individual PrPSc subunits stack to form amyloid fibers. We recently used limited proteolysis to map the β-strands and connecting loops that make up the PrPSc solenoid. Using high resolution SDS-PAGE followed by epitope analysis, and mass spectrometry, we identified positions ~116/118, 133-134, 141, 152-153, 162, 169 and 179 (murine numbering) as Proteinase K (PK) cleavage sites in PrPSc. Such sites likely define loops and/or borders of β-strands, helping us to predict the threading of the β-solenoid. We have now extended this approach to recombinant PrPSc (recPrPSc). The term recPrPSc refers to bona fide recombinant prions prepared by PMCA, exhibiting infectivity with attack rates of ~100%. Limited proteolysis of mouse and bank vole recPrPSc species yielded N-terminally truncated PK-resistant fragments similar to those seen in brain-derived PrPSc, albeit with varying relative yields. Along with these fragments, doubly N- and C-terminally truncated fragments, in particular ~89/97-152, were detected in some recPrPSc preparations; similar fragments are characteristic of atypical strains of brain-derived PrPSc. Our results suggest a shared architecture of recPrPSc and brain PrPSc prions. The observed differences, in particular the distinct yields of specific PK-resistant fragments, are likely due to differences in threading which result in the specific biochemical characteristics of recPrPSc. Furthermore, recombinant PrPSc offers exciting opportunities for structural studies unachievable with brain-derived PrPSc.

The Antidiabetic Mechanisms of Polyphenols Related to Increased Glucagon-Like Peptide-1 (GLP1 and Insulin Signaling

Directory of Open Access Journals (Sweden)

J. Abraham Domínguez Avila

2017-05-01

Full Text Available Type-2 diabetes mellitus (T2DM is an endocrine disease related to impaired/absent insulin signaling. Dietary habits can either promote or mitigate the onset and severity of T2DM. Diets rich in fruits and vegetables have been correlated with a decreased incidence of T2DM, apparently due to their high polyphenol content. Polyphenols are compounds of plant origin with several documented bioactivities related to health promotion. The present review describes the antidiabetic effects of polyphenols, specifically related to the secretion and effects of insulin and glucagon-like peptide 1 (GLP1, an enteric hormone that stimulates postprandial insulin secretion. The evidence suggests that polyphenols from various sources stimulate L-cells to secrete GLP1, increase its half-life by inhibiting dipeptidyl peptidase-4 (DPP4, stimulate β-cells to secrete insulin and stimulate the peripheral response to insulin, increasing the overall effects of the GLP1-insulin axis. The glucose-lowering potential of polyphenols has been evidenced in various acute and chronic models of healthy and diabetic organisms. Some polyphenols appear to exert their effects similarly to pharmaceutical antidiabetics; thus, rigorous clinical trials are needed to fully validate this claim. The broad diversity of polyphenols has not allowed for entirely describing their mechanisms of action, but the evidence advocates for their regular consumption.

The effects of variations in dose and method of administration on glucagon like peptide-2 activity in the rat

DEFF Research Database (Denmark)

Kaji, Tatsuru; Tanaka, Hiroaki; Holst, Jens Juul

2008-01-01

Glucagon-like peptide-2 (GLP-2) is a potent, intestinal-specific trophic hormone. However, the relationship between the dose and timing of GLP-2 administration and these trophic effects is not clear. We investigated the effects of variations in the dose and timing of GLP-2 administration on its...

Over-expression of Follistatin-like 3 attenuates fat accumulation and improves insulin sensitivity in mice

DEFF Research Database (Denmark)

Brandt, Claus; Hansen, Rasmus Hvass; Hansen, Jakob Bondo

2015-01-01

-fat feeding. Body weight, food intake, fat accumulation by MR scanning, and glucose, insulin and glucagon tolerance were evaluated, as was the response in body weight and metabolic parameters to 24h fasting. Effects of fstl3 on pancreatic insulin and glucagon content, and pancreatic islet morphology were......OBJECTIVE: Follistatin-like 3 (fstl3), a natural inhibitor of members of the TGF-β family, increases during resistance training in human plasma. Fstl3 primarily binds myostatin and activin A, and thereby inhibits their functions. We hypothesize that blocking myostatin and activin A signalling....../glucagon ratio. Accordingly, fstl3 transfection improved counter-regulation to 24h fasting. CONCLUSION: Fstl3 over-expression regulates insulin and glucagon sensitivities through increased muscular insulin action, as well as increased hepatic glucagon sensitivity and pancreatic glucagon content....

GLP-1 receptor stimulation depresses heart rate variability and inhibits neurotransmission to cardiac vagal neurons.

Science.gov (United States)

Griffioen, Kathleen J; Wan, Ruiqian; Okun, Eitan; Wang, Xin; Lovett-Barr, Mary Rachael; Li, Yazhou; Mughal, Mohamed R; Mendelowitz, David; Mattson, Mark P

2011-01-01

glucagon-like peptide 1 (GLP-1) is an incretin hormone released from the gut in response to food intake. Whereas GLP-1 acts in the periphery to inhibit glucagon secretion and stimulate insulin release, it also acts in the central nervous system to mediate autonomic control of feeding, body temperature, and cardiovascular function. Because of its role as an incretin hormone, GLP-1 receptor analogs are used as a treatment for type 2 diabetes. Central or peripheral administration of GLP-1 increases blood pressure and heart rate, possibly by activating brainstem autonomic nuclei and increasing vagus nerve activity. However, the mechanism(s) by which GLP-1 receptor stimulation affects cardiovascular function are unknown. We used the long-lasting GLP-1 receptor agonist Exendin-4 (Ex-4) to test the hypothesis that GLP-1 signalling modulates central parasympathetic control of heart rate. using a telemetry system, we assessed heart rate in mice during central Ex-4 administration. Heart rate was increased by both acute and chronic central Ex-4 administration. Spectral analysis indicated that the high frequency and low frequency powers of heart rate variability were diminished by Ex-4 treatment. Finally, Ex-4 decreased both excitatory glutamatergic and inhibitory glycinergic neurotransmission to preganglionic parasympathetic cardiac vagal neurons. these data suggest that central GLP-1 receptor stimulation diminishes parasympathetic modulation of the heart thereby increasing heart rate.

Effect of truncated glucagon-like peptide-1 [proglucagon-(78-107) amide] on endocrine secretion from pig pancreas, antrum, and nonantral stomach

DEFF Research Database (Denmark)

Orskov, C; Holst, J J; Nielsen, O V

1988-01-01

We studied the effect of truncated glucagon-like peptide-1 [naturally occurring GLP-1; proglucagon-(78-107) amide], a potent insulinotropic peptide from the pig ileum, on endocrine and exocrine secretion of potential gastrointestinal target organs using isolated perfused preparations of the porcine...... pancreas, antrum, and nonantral part of the stomach. Truncated GLP-1 significantly increased somatostatin secretion from the pancreas at 10(-10) mol/liter and more than doubled the secretion at 10(-9) mol/liter, but had no effect on either somatostatin or gastrin secretion from the antrum...... or on somatostatin secretion from the nonantral stomach in concentrations up to 10(-8) mol/liter. Insulin secretion from the pancreas (with 7 mmol/liter glucose in the perfusate) increased 2-fold with truncated GLP-1 at 10(-10) mol/liter and almost 5-fold at 10(-9) mol/liter. Pancreatic glucagon secretion...

Glucagon-like peptide 1 abolishes the postprandial rise in triglyceride concentrations and lowers levels of non-esterified fatty acids in humans

DEFF Research Database (Denmark)

Meier, J J; Gethmann, A; Götze, O

2006-01-01

and gastric emptying were assessed. METHODS: 14 healthy male volunteers were studied with an i.v. infusion of GLP-1 (1.2 pmol kg(-1) min(-1)) or placebo over 390 min in the fasting state. A solid test meal was served and gastric emptying was determined using a (13)C-labelled sodium octanoate breath test......AIMS/HYPOTHESIS: Diabetic dyslipidaemia contributes to the excess morbidity and mortality in patients with type 2 diabetes. Exogenous glucagon-like peptide 1 (GLP-1) lowers postprandial glycaemia predominantly by slowing gastric emptying. Therefore, the effects of GLP-1 on postprandial lipid levels....... Venous blood was drawn frequently for measurement of glucose, insulin, C-peptide, glucagon, GLP-1, triglycerides and NEFA. RESULTS: GLP-1 administration lowered fasting and postprandial glycaemia (pGastric emptying was delayed by GLP-1 compared with placebo (p

Glucagon-like peptide 1 interacts with ghrelin and leptin to regulate glucose metabolism and food intake through vagal afferent neuron signaling.

Science.gov (United States)

Ronveaux, Charlotte C; Tomé, Daniel; Raybould, Helen E

2015-04-01

Emerging evidence has suggested a possible physiologic role for peripheral glucagon-like peptide 1 (GLP-1) in regulating glucose metabolism and food intake. The likely site of action of GLP-1 is on vagal afferent neurons (VANs). The vagal afferent pathway is the major neural pathway by which information about ingested nutrients reaches the central nervous system and influences feeding behavior. Peripheral GLP-1 acts on VANs to inhibit food intake. The mechanism of the GLP-1 receptor (GLP-1R) is unlike other gut-derived receptors; GLP-1Rs change their cellular localization according to feeding status rather than their protein concentrations. It is possible that several gut peptides are involved in mediating GLP-1R translocation. The mechanism of peripheral GLP-1R translocation still needs to be elucidated. We review data supporting the role of peripheral GLP-1 acting on VANs in influencing glucose homeostasis and feeding behavior. We highlight evidence demonstrating that GLP-1 interacts with ghrelin and leptin to induce satiation. Our aim was to understand the mechanism of peripheral GLP-1 in the development of noninvasive antiobesity treatments. © 2015 American Society for Nutrition.

Development of a specific affinity-matured exosite inhibitor to MT1-MMP that efficiently inhibits tumor cell invasion in vitro and metastasis in vivo

DEFF Research Database (Denmark)

Botkjaer, Kenneth A; Kwok, Hang Fai; Terp, Mikkel G

2016-01-01

therapeutic target. Here, we report the identification of antibody fragments to MT1-MMP that potently and specifically inhibit its cell surface functions. Lead antibody clones displayed inhibitory activity towards pro-MMP-2 activation, collagen-film degradation and gelatin-film degradation, and were shown......The membrane-associated matrix metalloproteinase-14, MT1-MMP, has been implicated in pericellular proteolysis with an important role in cellular invasion of collagenous tissues. It is substantially upregulated in various cancers and rheumatoid arthritis, and has been considered as a potential...... to bind to the MT1-MMP catalytic domain outside the active site cleft, inhibiting binding to triple helical collagen. Affinity maturation using CDR3 randomization created a second generation of antibody fragments with dissociation constants down to 0.11 nM, corresponding to an improved affinity of 332...

Saccharomyces boulardii protease inhibits Clostridium difficile toxin A effects in the rat ileum.

Science.gov (United States)

Castagliuolo, I; LaMont, J T; Nikulasson, S T; Pothoulakis, C

1996-01-01

Saccharomyces boulardii, a nonpathogenic yeast, is effective in treating some patients with Clostridium difficile diarrhea and colitis. We have previously reported that S. boulardii inhibits rat ileal secretion in response to C. difficile toxin A possibly by releasing a protease that digests the intestinal receptor for this toxin (C. Pothoulakis, C. P. Kelly, M. A. Joshi, N. Gao, C. J. O'Keane, I. Castagliuolo, and J. T. LaMont, Gastroenterology 104: 1108-1115, 1993). The aim of this study was to purify and characterize this protease. S. boulardii protease was partially purified by gel filtration on Sephadex G-50 and octyl-Sepharose. The effect of S. boulardii protease on rat ileal secretion, epithelial permeability, and morphology in response to toxin A was examined in rat ileal loops in vivo. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified S. boulardii protease revealed a major band at 54 kDa. Pretreatment of rat ileal brush border (BB) membranes with partially purified protease reduced specific toxin A receptor binding (by 26%). Partially purified protease digested the toxin A molecule and significantly reduced its binding to BB membranes in vitro (by 42%). Preincubation of toxin A with S. boulardii protease inhibited ileal secretion (46% inhibition, P < 0.01), mannitol permeability (74% inhibition, P < 0.01), and histologic damage caused by toxin A. Thus, S. boulardii protease inhibits the intestinal effects of C. difficile toxin A by proteolysis of the toxin and inhibition of toxin A binding to its BB receptor. Our results may be relevant to the mechanism by which S. boulardii exerts its protective effects in C. difficile infection in humans. PMID:8945570

The glucagon-like peptide-1 receptor in the ventromedial hypothalamus reduces short-term food intake in male mice by regulating nutrient sensor activity.

Science.gov (United States)

Burmeister, Melissa A; Brown, Jacob D; Ayala, Jennifer E; Stoffers, Doris A; Sandoval, Darleen A; Seeley, Randy J; Ayala, Julio E

2017-12-01

Pharmacological activation of the glucagon-like peptide-1 receptor (GLP-1R) in the ventromedial hypothalamus (VMH) reduces food intake. Here, we assessed whether suppression of food intake by GLP-1R agonists (GLP-1RA) in this region is dependent on AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR). We found that pharmacological inhibition of glycolysis, and thus activation of AMPK, in the VMH attenuates the anorectic effect of the GLP-1R agonist exendin-4 (Ex4), indicating that glucose metabolism and inhibition of AMPK are both required for this effect. Furthermore, we found that Ex4-mediated anorexia in the VMH involved mTOR but not acetyl-CoA carboxylase, two downstream targets of AMPK. We support this by showing that Ex4 activates mTOR signaling in the VMH and Chinese hamster ovary (CHO)-K1 cells. In contrast to the clear acute pharmacological impact of the these receptors on food intake, knockdown of the VMH Glp1r conferred no changes in energy balance in either chow- or high-fat-diet-fed mice, and the acute anorectic and glucose tolerance effects of peripherally dosed GLP-1RA were preserved. These results show that the VMH GLP-1R regulates food intake by engaging key nutrient sensors but is dispensable for the effects of GLP-1RA on nutrient homeostasis. Copyright © 2017 the American Physiological Society.

Cross-system excision of chaperone-mediated proteolysis in chaperone-assisted recombinant protein production

Science.gov (United States)

Martínez-Alonso, Mónica; Villaverde, Antonio

2010-01-01

Main Escherichia coli cytosolic chaperones such as DnaK are key components of the control quality network designed to minimize the prevalence of polypeptides with aberrant conformations. This is achieved by both favoring refolding activities but also stimulating proteolytic degradation of folding reluctant species. This last activity is responsible for the decrease of the proteolytic stability of recombinant proteins when co-produced along with DnaK, where an increase in solubility might be associated to a decrease in protein yield. However, when DnaK and its co-chaperone DnaJ are co-produced in cultured insect cells or whole insect larvae (and expectedly, in other heterologous hosts), only positive, folding-related effects of these chaperones are observed, in absence of proteolysis-mediated reduction of recombinant protein yield. PMID:21326941

Delegation of Glucagon(r) in the school setting: a comparison of state legislation.

Science.gov (United States)

Wilt, Lori; Foley, Marie

2011-06-01

Delegation of nursing procedures and medication in school is fraught with legal and ethical concerns for the school nurse. Because nurses may be responsible for coordinating care for several school buildings, delegation of nursing care and medication administration has occurred out of necessity. Nurse Practice Acts in some states, but not all, allow for delegation of medication to unlicensed assistive personnel. This article explores Glucagon(®) delegation laws in the United States and presents an argument against such delegation in states where Nurse Practice Acts do not allow for delegation of medication to unlicensed assistive personnel.

Novel combination treatment of type 2 diabetes DPP-4 inhibition + metformin

Directory of Open Access Journals (Sweden)

Bo Ahrén

2008-04-01

Full Text Available Bo AhrénDepartment of Clinical Sciences, Division of Medicine, Lund University, Lund, SwedenAbstract: Inhibition of dipeptidyl peptidase-4 (DPP-4 as a novel therapy for type 2 diabetes is based on prevention of the inactivation process of bioactive peptides, the most important in the context of treatment of diabetes of which is glucagon-like peptide-1 (GLP-1. Most clinical experience with DPP-4 inhibition is based on vildagliptin (GalvusR, Novartis and sitagliptin (JanuviaR, Merck. These compounds improve glycemic control both in monotherapy and in combination with other oral hyperglycemic agents. Both have also been shown to efficiently improve glycemic control when added to ongoing metformin therapy in patients with inadequate glycemic control. Under that condition, they reduce HbA1c levels by 0.65%–1.1% (baseline HbA1c 7.2–8.7% in studies up to 52 weeks of duration in combination versus continuous therapy with metformin alone. Sitagliptin has also been examined in initial combination therapy with metformin have; HbA1c was reduced by this combination by 2.1% (baseline HbA1c 8.8% after 24 weeks of treatment. Both fasting and prandial glucose are reduced by DPP-4 inhibition in combination with metformin in association with improvement of insulin secretion and insulin resistance and increase in concentrations of active GLP-1. The combination of DPP-4 inhibition and metformin has been shown to be highly tolerable with very low risk of hypoglycemia. Hence, DPP-4 inhibition in combination with metformin is an efficient, safe and tolerable combination therapy for type 2 diabetes.Keywords: DPP-4 inhibition, sitagliptin, vildagliptin, metformin, type 2 diabetes

Dipeptidyl peptidase IV inhibition enhances the intestinotrophic effect of glucagon-like peptide-2 in rats and mice

DEFF Research Database (Denmark)

Hartmann, B; Thulesen, J; Kissow, Hannelouise

2000-01-01

; 15 mg VP; 40 microg GLP-2, 40 microg GLP-2+15 mg VP; 40 microg GLP-2 (3-33). Mice were treated for 10 days with: saline; 5 microg GLP-2; 5 microg GLP-2+1.5 mg VP; 25 microg GLP-2; 25 microg GLP-2 (3-33). In both cases, body weight, intestinal weight, length, and morphometric data were measured. After...... (4.68 +/- 0.11%, relative to body weight), compared with the two control groups, [3.01 +/- 0.06% (VP) and 2.94 +/- 0.07% (NaCl)] and GLP-2 alone (3.52 +/- 0.10%). In mice, the growth effect of 5 microg GLP-2+VP was comparable with that of 25 microg GLP-2. GLP-2 (3-33) had no effect in rats......, but it had a weak effect on intestinal growth in mice. The extensive GLP-2 degradation in rats can be reduced by VP, and DPP-IV inhibition markedly enhances the intestinotrophic effect of GLP-2 in both rats and mice. We propose that DPP-IV inhibition may be considered to enhance the efficacy of GLP-2...

Glucagon-like peptide-2 increases mesenteric blood flow in humans

DEFF Research Database (Denmark)

Bremholm, Lasse; Hornum, Mads; Henriksen, Birthe Merete

2008-01-01

a significant association between IV and SC administration of synthetic GLP-2 and changes in mesenteric blood flow. An exponential dose-response relationship was observed after IV infusion. The meal-induced changes in mesenteric blood flow over time were similar to those obtained by SC GLP-2. Thus, our results......OBJECTIVE: Mesenteric blood flow is believed to be influenced by digestion and absorption of ingested macronutrients. We hypothesized that the intestinotrophic hormone, GLP-2 (glucagons-like peptide 2), may be involved in the regulation of mesenteric blood flow. Changes in mesenteric blood flow...... were measured by Doppler ultrasound scanning of the superior mesenteric artery (SMA). The aim of the study was to demonstrate the influence of GLP-2 on this flow, expressed as changes in resistance index (RI). MATERIAL AND METHODS: A homogeneous group of 10 fasting healthy volunteers completed a 2-day...

Sustained influence of metformin therapy on circulating glucagon-like peptide-1 levels in individuals with and without type 2 diabetes

DEFF Research Database (Denmark)

Preiss, David; Dawed, Adem; Welsh, Paul

2017-01-01

AIMS: To investigate, in the Carotid Atherosclerosis: Metformin for Insulin Resistance (CAMERA) trial (NCT00723307), whether the influence of metformin on the glucagon-like peptide (GLP)-1 axis in individuals with and without type 2 diabetes (T2DM) is sustained and related to changes in glycaemia...

Bile-induced secretion of glucagon-like peptide-1: pathophysiological implications in type 2 diabetes?

DEFF Research Database (Denmark)

Knop, Filip Krag

2010-01-01

During the last decades it has become clear that bile acids not only act as simple fat solubilizers, but additionally represent complex hormonal metabolic integrators. Bile acids activate both nuclear receptors (controlling transcription of genes involved in for example bile acid, cholesterol......, and glucose metabolism) and the cell surface G protein-coupled receptor TGR5 (modulating energy expenditure in brown fat and muscle cells). It has been shown that TGR5 is expressed in enteroendocrine L cells, which secrete the potent glucose-lowering incretin hormone glucagon-like peptide-1 (GLP-1). Recently...

A novel Meloidogyne graminicola effector, MgGPP, is secreted into host cells and undergoes glycosylation in concert with proteolysis to suppress plant defenses and promote parasitism.

Directory of Open Access Journals (Sweden)

Jiansong Chen

2017-04-01

Full Text Available Plant pathogen effectors can recruit the host post-translational machinery to mediate their post-translational modification (PTM and regulate their activity to facilitate parasitism, but few studies have focused on this phenomenon in the field of plant-parasitic nematodes. In this study, we show that the plant-parasitic nematode Meloidogyne graminicola has evolved a novel effector, MgGPP, that is exclusively expressed within the nematode subventral esophageal gland cells and up-regulated in the early parasitic stage of M. graminicola. The effector MgGPP plays a role in nematode parasitism. Transgenic rice lines expressing MgGPP become significantly more susceptible to M. graminicola infection than wild-type control plants, and conversely, in planta, the silencing of MgGPP through RNAi technology substantially increases the resistance of rice to M. graminicola. Significantly, we show that MgGPP is secreted into host plants and targeted to the ER, where the N-glycosylation and C-terminal proteolysis of MgGPP occur. C-terminal proteolysis promotes MgGPP to leave the ER, after which it is transported to the nucleus. In addition, N-glycosylation of MgGPP is required for suppressing the host response. The research data provide an intriguing example of in planta glycosylation in concert with proteolysis of a pathogen effector, which depict a novel mechanism by which parasitic nematodes could subjugate plant immunity and promote parasitism and may present a promising target for developing new strategies against nematode infections.

Adjunctive Role of Glucagon-Like Peptide-1 Receptor Agonists in the Management of Type 1 Diabetes Mellitus.

Science.gov (United States)

Harris, Kira B; Boland, Cassie L

2016-09-01

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are commonly used in combination with insulin to manage type 2 diabetes mellitus, and four agents are currently approved for this indication: exenatide, liraglutide, dulaglutide, and albiglutide. The distinctive properties of GLP-1 RAs-potential hemoglobin A1c (A1C) reduction, weight loss, potential to reduce insulin doses, and lower hypoglycemia risk-have made these agents potential treatment options for patients with type 1 diabetes mellitus (T1DM) as well. These positive effects are due to glucose-dependent insulin secretion, reduced glucagon secretion, increased satiety, and delayed gastric emptying. Patients with T1DM are unable to suppress glucagon during meals, which contributes to postprandial hyperglycemia and may be improved with GLP-1 therapy. In this review, we evaluated the available literature on the clinical efficacy and safety of GLP-1 RAs in patients with T1DM. We conducted a search of the PubMed (1966-May 2016) and Ovid (1946-May 2016) databases. Abstracts presented at the scientific and clinical sessions of the American Diabetes Association and the American Association of Clinical Endocrinologists were also searched. The references of the published articles were also reviewed to identify additional studies appropriate for inclusion. All identified articles published in English were evaluated. Studies were included if they evaluated the clinical use or safety of GLP-1 RAs in patients with T1DM. Twelve studies were included, with four evaluating exenatide, one evaluating exenatide extended release, and seven evaluating liraglutide. Both exenatide and liraglutide showed significant reductions in hemoglobin A1C, plasma glucose concentration, body weight, and insulin doses when administered to patients with T1DM already receiving insulin therapy, without increasing the occurrence of hypoglycemia. Adverse effects were mostly gastrointestinal in nature but were mild and transient. Patients who may

Defining Conditions for Optimal Inhibition of Food Intake in Rats by a Grape-Seed Derived Proanthocyanidin Extract.

Science.gov (United States)

Serrano, Joan; Casanova-Martí, Àngela; Blay, Mayte; Terra, Ximena; Ardévol, Anna; Pinent, Montserrat

2016-10-20

Food intake depends on homeostatic and non-homeostatic factors. In order to use grape seed proanthocyanidins (GSPE) as food intake limiting agents, it is important to define the key characteristics of their bioactivity within this complex function. We treated rats with acute and chronic treatments of GSPE at different doses to identify the importance of eating patterns and GSPE dose and the mechanistic aspects of GSPE. GSPE-induced food intake inhibition must be reproduced under non-stressful conditions and with a stable and synchronized feeding pattern. A minimum dose of around 350 mg GSPE/kg body weight (BW) is needed. GSPE components act by activating the Glucagon-like peptide-1 (GLP-1) receptor because their effect is blocked by Exendin 9-39. GSPE in turn acts on the hypothalamic center of food intake control probably because of increased GLP-1 production in the intestine. To conclude, GSPE inhibits food intake through GLP-1 signaling, but it needs to be dosed under optimal conditions to exert this effect.

Surface expression and limited proteolysis of ADAM10 are increased by a dominant negative inhibitor of dynamin

Directory of Open Access Journals (Sweden)

Slack Barbara E

2011-05-01

Full Text Available Abstract Background The amyloid precursor protein (APP is cleaved by β- and γ-secretases to generate toxic amyloid β (Aβ peptides. Alternatively, α-secretases cleave APP within the Aβ domain, precluding Aβ formation and releasing the soluble ectodomain, sAPPα. We previously showed that inhibition of the GTPase dynamin reduced APP internalization and increased release of sAPPα, apparently by prolonging the interaction between APP and α-secretases at the plasma membrane. This was accompanied by a reduction in Aβ generation. In the present study, we investigated whether surface expression of the α-secretase ADAM (a disintegrin and metalloprotease10 is also regulated by dynamin-dependent endocytosis. Results Transfection of human embryonic kidney (HEK cells stably expressing M3 muscarinic receptors with a dominant negative dynamin I mutant (dyn I K44A, increased surface expression of both immature, and mature, catalytically active forms of co-expressed ADAM10. Surface levels of ADAM10 were unaffected by activation of protein kinase C (PKC or M3 receptors, indicating that receptor-coupled shedding of the ADAM substrate APP is unlikely to be mediated by inhibition of ADAM10 endocytosis in this cell line. Dyn I K44A strongly increased the formation of a C-terminal fragment of ADAM10, consistent with earlier reports that the ADAM10 ectodomain is itself a target for sheddases. The abundance of this fragment was increased in the presence of a γ-secretase inhibitor, but was not affected by M3 receptor activation. The dynamin mutant did not affect the distribution of ADAM10 and its C-terminal fragment between raft and non-raft membrane compartments. Conclusions Surface expression and limited proteolysis of ADAM10 are regulated by dynamin-dependent endocytosis, but are unaffected by activation of signaling pathways that upregulate shedding of ADAM substrates such as APP. Modulation of ADAM10 internalization could affect cellular behavior in two

Acid-Mediated Tumor Proteolysis: Contribution of Cysteine Cathepsins

Directory of Open Access Journals (Sweden)

Jennifer M Rothberg

2013-10-01

Full Text Available One of the noncellular microenvironmental factors that contribute to malignancy of solid tumors is acidic peritumoral pH. We have previously demonstrated that extracellular acidosis leads to localization of the cysteine pro-tease cathepsin B on the tumor cell membrane and its secretion. The objective of the present study was to determine if an acidic extracellular pH such as that observed in vivo (i.e., pHe 6.8 affects the activity of proteases, e.g., cathepsin B, that contribute to degradation of collagen IV by tumor cells when grown in biologically relevant three-dimensional (3D cultures. For these studies, we used 1 3D reconstituted basement membrane overlay cultures of human carcinomas, 2 live cell imaging assays to assess proteolysis, and 3 in vivo imaging of active tumor proteases. At pHe 6.8, there were increases in pericellular active cysteine cathepsins and in degradation of dye-quenched collagen IV, which was partially blocked by a cathepsin B inhibitor. Imaging probes for active cysteine cathepsins localized to tumors in vivo. The amount of bound probe decreased in tumors in bicarbonate-treated mice, a treatment previously shown to increase peritumoral pHe and reduce local invasion of the tumors. Our results are consistent with the acid-mediated invasion hypothesis and with a role for cathepsin B in promoting degradation of a basement membrane protein substrate, i.e., type IV collagen, in an acidic peritumoral environment.

Amino acids and insulin act additively to regulate components of the ubiquitin-proteasome pathway in C2C12 myotubes

Directory of Open Access Journals (Sweden)

Lomax Michael A

2007-03-01

Full Text Available Abstract Background The ubiquitin-proteasome system is the predominant pathway for myofibrillar proteolysis but a previous study in C2C12 myotubes only observed alterations in lysosome-dependent proteolysis in response to complete starvation of amino acids or leucine from the media. Here, we determined the interaction between insulin and amino acids in the regulation of myotube proteolysis Results Incubation of C2C12 myotubes with 0.2 × physiological amino acids concentration (0.2 × PC AA, relative to 1.0 × PC AA, significantly increased total proteolysis and the expression of 14-kDa E2 ubiquitin conjugating enzyme (p Conclusion In a C2C12 myotube model of myofibrillar protein turnover, amino acid limitation increases proteolysis in a ubiquitin-proteasome-dependent manner. Increasing amino acids or leucine alone, act additively with insulin to down regulate proteolysis and expression of components of ubiquitin-proteasome pathway. The effects of amino acids on proteolysis but not insulin and leucine, are blocked by inhibition of the mTOR signalling pathway.

Glucagon-like peptide receptor agonists and dipeptidyl peptidase-4 inhibitors in the treatment of diabetes: a review of clinical trials

DEFF Research Database (Denmark)

Madsbad, Sten; Krarup, Thure; Deacon, Carolyn F

2008-01-01

-acting glucagon-like peptide-1 receptor agonists liraglutide and exenatide long-acting release reduce haemoglobin A1c by about 1.0-2.0% and have fewer gastrointestinal side-effects. The orally available dipeptidyl peptidase-4 inhibitors, that is sitagliptin and vildagliptin reduce haemoglobin A1c by 0...

Effect of Age on Blood Glucose and Plasma Insulin, Glucagon, Ghrelin, CCK, GIP, and GLP-1 Responses to Whey Protein Ingestion

Directory of Open Access Journals (Sweden)

Caroline Giezenaar

2017-12-01

Full Text Available Protein-rich supplements are used widely to prevent and manage undernutrition in older people. We have previously shown that healthy older, compared to younger, adults have less suppression of energy intake by whey protein—although the effects of age on appetite-related gut hormones are largely unknown. The aim of this study was to determine and compare the acute effects of whey protein loads on blood glucose and plasma gut hormone concentrations in older and younger adults. Sixteen healthy older (eight men, eight women; mean ± SEM: age: 72 ± 1 years; body mass index: 25 ± 1 kg/m2 and 16 younger (eight men, eight women; 24 ± 1 years; 23 ± 0.4 kg/m2 adults were studied on three occasions in which they ingested 30 g (120 kcal or 70 g (280 kcal whey protein, or a flavored-water control drink (~2 kcal. At regular intervals over 180 min, blood glucose and plasma insulin, glucagon, ghrelin, cholecystokinin (CCK, gastric inhibitory peptide (GIP, and glucagon-like peptide-1 (GLP-1 concentrations were measured. Plasma ghrelin was dose-dependently suppressed and insulin, glucagon, CCK, GIP, and GLP-1 concentrations were dose-dependently increased by the whey protein ingestion, while blood glucose concentrations were comparable during all study days. The stimulation of plasma CCK and GIP concentrations was greater in older than younger adults. In conclusion, orally ingested whey protein resulted in load-dependent gut hormone responses, which were greater for plasma CCK and GIP in older compared to younger adults.

GLP-1 and exendin-4 for imaging endocrine pancreas. A review. Labelled glucagon-like peptide-1 analogues: past, present and future

International Nuclear Information System (INIS)

Hubalewska-Dydejczyk, A.; Sowa-Staszczak, A.; Tomaszuk, M.; Stefańska, A.

2015-01-01

Glucagon-like peptide 1 (GLP-1) receptors expression has been found on many types of cancer cells. In case of benign insulinoma the density of those receptors is even higher than the density of somatostatin receptors. This article presents the results of clinical trials proving the utility of GLP-1 receptors imaging. Scintigraphy or positron emission tomography with the use of GLP-1 analogues labelled with appropriate radioisotopes ( 111I n, 99m Tc, 68 Ga, 18 F or 64 Cu) seem to be superior compared with other available techniques in diagnosis of hardly detectable benign insulinoma. While surgery is the only effective therapy for insulinoma patients, therefore proper preoperative localization of the tumor allows sparing operation. Glucagon-like peptide 1 receptors might become also a target for imaging of other tumors such as gastrinoma, pheochromocytoma and medullary thyroid cancer (MTC), which also were shown to over express this type of receptors. However, studies with larger groups of patients are required to prove the clinical usefulness of this indication. Moreover GLP-1 receptor imaging seems to be a potential tool to evaluate pancreatic beta cell mass (BCM). It may be useful in the early diagnosis of beta cell loss in preclinical phases of diabetes. The panceratic beta cells imaging may influence the prophylaxis of diabetes and management of diabetic patients. Presented results of clinical trials prove that glucagon-like peptide 1 receptor imaging might become helpful diagnostic strategy particularly in case of patients with benign insulinoma tumors, but also patients with gastrinoma, pheochromocytoma, medullary thyroid cancer and diabetes.

Incretin Effect and Glucagon Responses to Oral and Intravenous Glucose in Patients with Maturity Onset Diabetes of the Young - Type 2 and Type 3

DEFF Research Database (Denmark)

Ostoft, Signe H; Bagger, Jonatan I; Hansen, Torben

2014-01-01

Maturity onset diabetes of the young (MODY) is a clinically and genetically heterogeneous subgroup of non-autoimmune diabetes, constituting 1-2% of all diabetes. Because little is known about incretin function in patients with MODY, we studied the incretin effect and hormone responses to oral...... and intravenous glucose loads in patients with glucokinase (GCK)-diabetes (MODY2) and hepatocyte nuclear factor 1α (HNF1A)-diabetes (MODY3), respectively, and in matched healthy control individuals (CTRLs). Both MODY groups exhibited glucose intolerance after oral glucose (most pronounced in patients with HNF1A-diabetes...... incretin effect and inappropriate glucagon responses, whereas incretin effect and glucagon response to oral glucose remain unaffected in GCK-diabetes, reflecting important pathogenetic differences between the two MODY forms....

MBTPS2 mutations cause defective regulated intramembrane proteolysis in X-linked osteogenesis imperfecta

Science.gov (United States)

Lindert, Uschi; Cabral, Wayne A.; Ausavarat, Surasawadee; Tongkobpetch, Siraprapa; Ludin, Katja; Barnes, Aileen M.; Yeetong, Patra; Weis, Maryann; Krabichler, Birgit; Srichomthong, Chalurmpon; Makareeva, Elena N.; Janecke, Andreas R.; Leikin, Sergey; Röthlisberger, Benno; Rohrbach, Marianne; Kennerknecht, Ingo; Eyre, David R.; Suphapeetiporn, Kanya; Giunta, Cecilia; Marini, Joan C.; Shotelersuk, Vorasuk

2016-01-01

Osteogenesis imperfecta (OI) is a collagen-related bone dysplasia. We identified an X-linked recessive form of OI caused by defects in MBTPS2, which encodes site-2 metalloprotease (S2P). MBTPS2 missense mutations in two independent kindreds with moderate/severe OI cause substitutions at highly conserved S2P residues. Mutant S2P has normal stability, but impaired functioning in regulated intramembrane proteolysis (RIP) of OASIS, ATF6 and SREBP transcription factors, consistent with decreased proband secretion of type I collagen. Further, hydroxylation of the collagen lysine residue (K87) critical for crosslinking is reduced in proband bone tissue, consistent with decreased lysyl hydroxylase 1 in proband osteoblasts. Reduced collagen crosslinks presumptively undermine bone strength. Also, proband osteoblasts have broadly defective differentiation. These mutations provide evidence that RIP plays a fundamental role in normal bone development. PMID:27380894

An overview of once-weekly glucagon-like peptide-1 receptor agonists--available efficacy and safety data and perspectives for the future

DEFF Research Database (Denmark)

Madsbad, S; Kielgast, U; Asmar, M

2011-01-01

Incretin-based therapies, such as the injectable glucagon-like peptide-1 (GLP-1) receptor agonists and orally administered dipeptidyl peptidase-4 (DPP-4) inhibitors, have recently been introduced into clinical practice. At present, the GLP-1 receptor agonists need to be administered once or twice...

Common variants in the hERG (KCNH2) voltage-gated potassium channel are associated with altered fasting and glucose-stimulated plasma incretin and glucagon responses

DEFF Research Database (Denmark)

Engelbrechtsen, Line; Mahendran, Yuvaraj; Jonsson, Anna

2018-01-01

BACKGROUND: Patients with long QT syndrome due to rare loss-of-function mutations in the human ether-á-go-go-related gene (hERG) have prolonged QT interval, risk of arrhythmias, increased secretion of insulin and incretins and impaired glucagon response to hypoglycemia. This is caused by a dysfun......BACKGROUND: Patients with long QT syndrome due to rare loss-of-function mutations in the human ether-á-go-go-related gene (hERG) have prolonged QT interval, risk of arrhythmias, increased secretion of insulin and incretins and impaired glucagon response to hypoglycemia. This is caused...... by a dysfunctional Kv11.1 voltage-gated potassium channel. Based on these findings in patients with rare variants in hERG, we hypothesized that common variants in hERG may also lead to alterations in glucose homeostasis. Subsequently, we aimed to evaluate the effect of two common gain-of-function variants in hERG...... in hERG on QT-interval and circulation levels of incretins, insulin and glucagon. The Danish population-based Inter99 cohort (n = 5895) was used to assess the effect of common variants on QT-interval. The Danish ADDITION-PRO cohort was used (n = 1329) to study genetic associations with levels of GLP-1...

Plant lectin can target receptors containing sialic acid, exemplified by podoplanin, to inhibit transformed cell growth and migration.

Directory of Open Access Journals (Sweden)

Jhon Alberto Ochoa-Alvarez

Full Text Available Cancer is a leading cause of death of men and women worldwide. Tumor cell motility contributes to metastatic invasion that causes the vast majority of cancer deaths. Extracellular receptors modified by α2,3-sialic acids that promote this motility can serve as ideal chemotherapeutic targets. For example, the extracellular domain of the mucin receptor podoplanin (PDPN is highly O-glycosylated with α2,3-sialic acid linked to galactose. PDPN is activated by endogenous ligands to induce tumor cell motility and metastasis. Dietary lectins that target proteins containing α2,3-sialic acid inhibit tumor cell growth. However, anti-cancer lectins that have been examined thus far target receptors that have not been identified. We report here that a lectin from the seeds of Maackia amurensis (MASL with affinity for O-linked carbohydrate chains containing sialic acid targets PDPN to inhibit transformed cell growth and motility at nanomolar concentrations. Interestingly, the biological activity of this lectin survives gastrointestinal proteolysis and enters the cardiovascular system to inhibit melanoma cell growth, migration, and tumorigenesis. These studies demonstrate how lectins may be used to help develop dietary agents that target specific receptors to combat malignant cell growth.

Structural Basis for Regulated Proteolysis by the α-Secretase ADAM10.

Science.gov (United States)

Seegar, Tom C M; Killingsworth, Lauren B; Saha, Nayanendu; Meyer, Peter A; Patra, Dhabaleswar; Zimmerman, Brandon; Janes, Peter W; Rubinstein, Eric; Nikolov, Dimitar B; Skiniotis, Georgios; Kruse, Andrew C; Blacklow, Stephen C

2017-12-14

Cleavage of membrane-anchored proteins by ADAM (a disintegrin and metalloproteinase) endopeptidases plays a key role in a wide variety of biological signal transduction and protein turnover processes. Among ADAM family members, ADAM10 stands out as particularly important because it is both responsible for regulated proteolysis of Notch receptors and catalyzes the non-amyloidogenic α-secretase cleavage of the Alzheimer's precursor protein (APP). We present here the X-ray crystal structure of the ADAM10 ectodomain, which, together with biochemical and cellular studies, reveals how access to the enzyme active site is regulated. The enzyme adopts an unanticipated architecture in which the C-terminal cysteine-rich domain partially occludes the enzyme active site, preventing unfettered substrate access. Binding of a modulatory antibody to the cysteine-rich domain liberates the catalytic domain from autoinhibition, enhancing enzymatic activity toward a peptide substrate. Together, these studies reveal a mechanism for regulation of ADAM activity and offer a roadmap for its modulation. Copyright © 2017 Elsevier Inc. All rights reserved.

Moderate alcohol consumption is associated with improved insulin sensitivity, reduced basal insulin secretion rate and lower fasting glucagon concentration in healthy women

DEFF Research Database (Denmark)

Bonnet, F; Disse, E; Laville, M

2012-01-01

Moderate alcohol consumption is associated with a reduced risk of type 2 diabetes with a stronger effect in women. As the underlying mechanisms remain poorly characterised, we investigated its relationship with insulin resistance, insulin secretion, clearance of insulin and glucagon concentration....

Sustained glucagon-like peptide 1 expression from encapsulated transduced cells to treat obese diabetic rats

OpenAIRE

Moralejo, Daniel; Yanay, Ofer; Kernan, Kelly; Bailey, Adam; Lernmark, Ake; Osborne, William

2011-01-01

Obesity and type 2 diabetes (T2D) are two prevalent chronic diseases that have become a major public health concern in industrialized countries. T2D is characterized by hyperglycemia and islet beta cell dysfunction. Glucagon-like peptide 1 (GLP-1) promotes β cell proliferation and neogenesis and has a potent insulinotropic effect. Leptin receptor deficient male rats are obese and diabetic and provide a model of T2D. We hypothesized that their treatment by sustained expression of GLP-1 using e...

Steviol Glycoside Rebaudioside A Induces Glucagon-like Peptide-1 and Peptide YY Release in a Porcine ex Vivo Intestinal Model

NARCIS (Netherlands)

Ripken, D.; Wielen, N. van der; Wortelboer, H.M.; Meijerink, J.; Witkamp, R.F.; Hendriks, H.F.J.

2014-01-01

Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are hormones important for satiation and are involved in the process called “ileal brake”. The aim of this study was to investigate the GLP-1- and PYY-stimulating efficacy of rebaudioside A, casein, and sucrose. This was studied using tissue

Steviol glycoside rebaudioside A induces glucagon-like peptide-1 and peptide YY release in a porcine ex vivo intestinal model

NARCIS (Netherlands)

Ripken, D.; Wielen, van der N.; Wortelboer, H.M.; Meijerink, J.; Witkamp, R.F.; Hendriks, H.F.

2014-01-01

Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are hormones important for satiation and are involved in the process called "ileal brake". The aim of this study was to investigate the GLP-1- and PYY-stimulating efficacy of rebaudioside A, casein, and sucrose. This was studied using tissue

GLP-1/glucagon coagonism restores leptin responsiveness in obese mice chronically maintained on an obesogenic diet

DEFF Research Database (Denmark)

Clemmensen, Christoffer; Chabenne, Joseph; Finan, Brian

2014-01-01

We recently reported restoration of leptin responsiveness in diet-induced obese (DIO) mice using a pharmacologically optimized, polyethylene-glycolated (PEG)-leptin analog in combination with exendin-4 or FGF21. However, the return of leptin action required discontinuation of high-fat diet (HFD...... cotreatment. In summary, we report that GLP-1/glucagon coagonism restores leptin responsiveness in mice maintained on a HFD, thus emphasizing the translational value of this polypharmacotherapy for the treatment of obesity and diabetes....

Effect of monoclonal antibodies on limited proteolysis of native glycoprotein gD of herpes simplex virus type 1

International Nuclear Information System (INIS)

Eisenberg, R.J.; Long, D.; Pereira, L.; Hampar, B.; Zweig, M.; Cohen, G.H.

1982-01-01

We examined the properties of 17 monoclonal antibodies to glycoprotein gD of herpes simplex type 1 (HSV-1) (gD-1) and HSV-2 (gD-2). The antibodies recognized eight separate determinants of gD, based on differences in radioimmuno-precipitation and neutralization assays. The determinants were distributed as follows: three were gD-1 specific, one was gD-2 specific, and four were type common. Several type-specific and type-common determinants appeared to be involved in neutralization. We developed a procedure for examining the effect that binding of monoclonal antibody has on proteolysis of native gD-1 by Staphylococcus aureus protease V8. We showed that several different patterns of protease V8 cleavage were obtained, depending on the monoclonal antibody used. The proteolysis patterns were generally consistent with the immunological groupings. With four groups of antibodies, we found that fragments of gD-1 remained bound to antibody after V8 treatment. A 38,000-dalton fragment remained bound to antibodies in three different groups of monoclonal antibodies. This fragment appeared to contain one type-common and two type-specific determinants. A 12,000-dalton fragment remained bound to antibodies belonging to one type-common group of monoclonal antibodies. Tryptic peptide analysis revealed that the 12,000-dalton fragment represented a portion of the 38,000-dalton fragment and was enriched in a type-common arginine tryptic peptide

Dynamic assembly, localization and proteolysis of the Bacillus subtilis SMC complex

Directory of Open Access Journals (Sweden)

Rinn Cornelia

2005-06-01

Full Text Available Abstract Background SMC proteins are key components of several protein complexes that perform vital tasks in different chromosome dynamics. Bacterial SMC forms a complex with ScpA and ScpB that is essential for chromosome arrangement and segregation. The complex localizes to discrete centres on the nucleoids that during most of the time of the cell cycle localize in a bipolar manner. The complex binds to DNA and condenses DNA in an as yet unknown manner. Results We show that in vitro, ScpA and ScpB form different complexes with each other, among which the level of the putative 2 ScpA/4 ScpB complex showed a pronounced decrease in level upon addition of SMC protein. Different mutations of the ATPase-binding pocket of SMC reduced, but did not abolish interaction of mutant SMC with ScpA and ScpB. The loss of SMC ATPase activity led to a loss of function in vivo, and abolished proper localization of the SMC complex. The formation of bipolar SMC centres was also lost after repression of gyrase activity, and was abnormal during inhibition of replication, resulting in single central clusters. Resumption of replication quickly re-established bipolar SMC centres, showing that proper localization depends on ongoing replication. We also found that the SMC protein is subject to induced proteolysis, most strikingly as cells enter stationary phase, which is partly achieved by ClpX and LonA proteases. Atomic force microscopy revealed the existence of high order rosette-like SMC structures in vitro, which might explain the formation of the SMC centres in vivo. Conclusion Our data suggest that a ScpA/ScpB sub-complex is directly recruited into the SMC complex. This process does not require SMC ATPase activity, which, however, appears to facilitate loading of ScpA and ScpB. Thus, the activity of SMC could be regulated through binding and release of ScpA and ScpB, which has been shown to affect SMC ATPase activity. The proper bipolar localization of the SMC

The T allele of rs7903146 TCF7L2 is associated with impaired insulinotropic action of incretin hormones, reduced 24 h profiles of plasma insulin and glucagon, and increased hepatic glucose production in young healthy men

DEFF Research Database (Denmark)

Pilgaard, K; Jensen, C; Schou, J

2009-01-01

h glucose, insulin and glucagon profiles; OGTT; mixed meal test; IVGTT; hyperglycaemic clamp with co-infusion of glucagon-like peptide (GLP)-1 or glucose-dependent insulinotropic polypeptide (GIP); and a euglycaemic-hyperinsulinaemic clamp combined with glucose tracer infusion to study hepatic...... and peripheral insulin action. RESULTS: Carriers of the T allele were characterised by reduced 24 h insulin concentrations (p ...-phase insulinotropic action of GLP-1 (p = 0.03) and GIP (p = 0.07) during a 7 mmol/l hyperglycaemic clamp. Secretion of GLP-1 and GIP during the mixed meal test was normal. Despite elevated hepatic glucose production, carriers of the T allele had significantly reduced 24 h glucagon concentrations (p

Molecular Characterization of the RNA-Binding Protein Quaking-a in Megalobrama amblycephala: Response to High-Carbohydrate Feeding and Glucose/Insulin/Glucagon Treatment

Directory of Open Access Journals (Sweden)

Hua-Juan Shi

2018-04-01

Full Text Available The RNA-binding protein quaking-a (Qkia was cloned from the liver of blunt snout bream Megalobrama amblycephala through the rapid amplification of cDNA ends method, with its potential role in glucose metabolism investigated. The full-length cDNA of qkia covered 1,718 bp, with an open reading frame of 1,572 bp, which encodes 383 AA. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (97–99% among most fish and other higher vertebrates. The mRNA of qkia was detected in all examined organs/tissues. Then, the plasma glucose levels and tissue qkia expressions were determined in fish intraperitoneally injected with glucose [1.67 g per kg body weight (BW], insulin (0.052 mg/kg BW, and glucagon (0.075 mg/kg BW respectively, as well as in fish fed two dietary carbohydrate levels (31 and 41% for 12 weeks. Glucose administration induced a remarkable increase of plasma glucose with the highest value being recorded at 1 h. Thereafter, it reduced to the basal value. After glucose administration, qkia expressions significantly decreased with the lowest value being recorded at 1 h in liver and muscle and 8 h in brain, respectively. Then they gradually returned to the basal value. The insulin injection induced a significant decrease of plasma glucose with the lowest value being recorded at 1 h, whereas the opposite was true after glucagon load (the highest value was gained at 4 h. Subsequently, glucose levels gradually returned to the basal value. After insulin administration, the qkia expressions significantly decreased with the lowest value being attained at 2 h in brain and muscle and 1 h in liver, respectively. However, glucagon significantly stimulated the expressions of qkia in tissues with the highest value being gained at 6 h. Moreover, high dietary carbohydrate levels remarkably increased plasma glucose levels, but down-regulated the transcriptions of qkia in tissues. These results indicated that the gene of blunt

Differential effects of glucagon-like peptide-1 on microvascular recruitment and glucose metabolism in short- and long-term Insulin resistance

DEFF Research Database (Denmark)

Sjøberg, Kim Anker; Rattigan, Stephen; Jeppesen, Jacob Fuglsbjerg

2015-01-01

Acute infusion of glucagon-like-peptide-1 (GLP-1) has potent effects on blood flow distribution through the microcirculation in healthy humans and rats. High fat diet induces impairments in insulin-mediated microvascular recruitment (MVR) and muscle glucose uptake, and here we examined whether......-mediated glucose uptake in skeletal muscle by 90% (Prights...

Effects of glucagon-like peptide 1 on counterregulatory hormone responses, cognitive functions, and insulin secretion during hyperinsulinemic, stepped hypoglycemic clamp experiments in healthy volunteers

DEFF Research Database (Denmark)

Nauck, Michael A; Heimesaat, Markus M; Behle, Kai

2002-01-01

and neuroglucopenic symptoms were assessed, and cognitive function was tested at each plateau. Insulin secretion rates were estimated by deconvolution (two-compartment model of C-peptide kinetics). At insulin concentrations of approximately 45 mU/liter, glucose infusion rates were similar with and without GLP-1 (P......Glucagon-like peptide 1 (GLP-1) and analogues are being evaluated as a new therapeutic principle for the treatment of type 2 diabetes. GLP-1 suppresses glucagon secretion, which could lead to disturbances of hypoglycemia counterregulation. This has, however, not been tested. Nine healthy volunteers.......97). The other counterregulatory hormones and autonomic or neuroglucopenic symptom scores increased, and cognitive functions decreased with decreasing glucose concentrations, but there were no significant differences comparing experiments with GLP-1 or placebo, except for a significant reduction of GH responses...

Glucagon-like peptide 1 receptor activation regulates cocaine actions and dopamine homeostasis in the lateral septum by decreasing arachidonic acid levels

DEFF Research Database (Denmark)

Reddy, I A; Pino, J A; Weikop, P

2016-01-01

Agonism of the glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) has been effective at treating aspects of addictive behavior for a number of abused substances, including cocaine. However, the molecular mechanisms and brain circuits underlying the therapeutic effects of GLP-1R signaling on cocain...

Incretin physiology beyond glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide: cholecystokinin and gastrin peptides

DEFF Research Database (Denmark)

Rehfeld, J F

2011-01-01

and neonatal islets express significant amounts of gastrin, and human as well as porcine islet cells express the gastrin/CCK-B receptor abundantly. Therefore, exogenous gastrin and CCK peptides stimulate insulin and glucagon secretion in man. Accordingly, endogenous hypergastrinaemia is accompanied by islet...... cell hyperplasia and increased insulin secretion. Conventionally, the effect of gastrointestinal hormones on insulin secretion (the incretin effect) has been defined and quantified in relation to oral versus intravenous glucose loadings. Under these unphysiological conditions, the release of gastrin...

Crystal structure of the ligand-bound glucagon-like peptide-1 receptor extracellular domain.

Science.gov (United States)

Runge, Steffen; Thøgersen, Henning; Madsen, Kjeld; Lau, Jesper; Rudolph, Rainer

2008-04-25

The glucagon-like peptide-1 receptor (GLP-1R) belongs to Family B1 of the seven-transmembrane G protein-coupled receptors, and its natural agonist ligand is the peptide hormone glucagon-like peptide-1 (GLP-1). GLP-1 is involved in glucose homeostasis, and activation of GLP-1R in the plasma membrane of pancreatic beta-cells potentiates glucose-dependent insulin secretion. The N-terminal extracellular domain (nGLP-1R) is an important ligand binding domain that binds GLP-1 and the homologous peptide Exendin-4 with differential affinity. Exendin-4 has a C-terminal extension of nine amino acid residues known as the "Trp cage", which is absent in GLP-1. The Trp cage was believed to interact with nGLP-1R and thereby explain the superior affinity of Exendin-4. However, the molecular details that govern ligand binding and specificity of nGLP-1R remain undefined. Here we report the crystal structure of human nGLP-1R in complex with the antagonist Exendin-4(9-39) solved by the multiwavelength anomalous dispersion method to 2.2A resolution. The structure reveals that Exendin-4(9-39) is an amphipathic alpha-helix forming both hydrophobic and hydrophilic interactions with nGLP-1R. The Trp cage of Exendin-4 is not involved in binding to nGLP-1R. The hydrophobic binding site of nGLP-1R is defined by discontinuous segments including primarily a well defined alpha-helix in the N terminus of nGLP-1R and a loop between two antiparallel beta-strands. The structure provides for the first time detailed molecular insight into ligand binding of the human GLP-1 receptor, an established target for treatment of type 2 diabetes.

LX4211 increases serum glucagon-like peptide 1 and peptide YY levels by reducing sodium/glucose cotransporter 1 (SGLT1)-mediated absorption of intestinal glucose.

Science.gov (United States)

Powell, David R; Smith, Melinda; Greer, Jennifer; Harris, Angela; Zhao, Sharon; DaCosta, Christopher; Mseeh, Faika; Shadoan, Melanie K; Sands, Arthur; Zambrowicz, Brian; Ding, Zhi-Ming

2013-05-01

LX4211 [(2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-ethoxybenzyl)phenyl)-6-(methylthio)tetrahydro-2H-pyran-3,4,5-triol], a dual sodium/glucose cotransporter 1 (SGLT1) and SGLT2 inhibitor, is thought to decrease both renal glucose reabsorption by inhibiting SGLT2 and intestinal glucose absorption by inhibiting SGLT1. In clinical trials in patients with type 2 diabetes mellitus (T2DM), LX4211 treatment improved glycemic control while increasing circulating levels of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). To better understand how LX4211 increases GLP-1 and PYY levels, we challenged SGLT1 knockout (-/-) mice, SGLT2-/- mice, and LX4211-treated mice with oral glucose. LX4211-treated mice and SGLT1-/- mice had increased levels of plasma GLP-1, plasma PYY, and intestinal glucose during the 6 hours after a glucose-containing meal, as reflected by area under the curve (AUC) values, whereas SGLT2-/- mice showed no response. LX4211-treated mice and SGLT1-/- mice also had increased GLP-1 AUC values, decreased glucose-dependent insulinotropic polypeptide (GIP) AUC values, and decreased blood glucose excursions during the 6 hours after a challenge with oral glucose alone. However, GLP-1 and GIP levels were not increased in LX4211-treated mice and were decreased in SGLT1-/- mice, 5 minutes after oral glucose, consistent with studies linking decreased intestinal SGLT1 activity with reduced GLP-1 and GIP levels 5 minutes after oral glucose. These data suggest that LX4211 reduces intestinal glucose absorption by inhibiting SGLT1, resulting in net increases in GLP-1 and PYY release and decreases in GIP release and blood glucose excursions. The ability to inhibit both intestinal SGLT1 and renal SGLT2 provides LX4211 with a novel dual mechanism of action for improving glycemic control in patients with T2DM.

Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes

International Nuclear Information System (INIS)

Yano, Claudia L; Ventrucci, Gislaine; Field, William N; Tisdale, Michael J; Gomes-Marcondes, Maria Cristina C

2008-01-01

Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C 2 C 12 muscle cells. WF decreased the viability of C 2 C 12 myotubes, especially at concentrations of 20–25 μg.mL -1 . There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model

Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes

Directory of Open Access Journals (Sweden)

Tisdale Michael J

2008-01-01

Full Text Available Abstract Background Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. Methods In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF, which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells. Results WF decreased the viability of C2C12 myotubes, especially at concentrations of 20–25 μg.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. Conclusion These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model.

Rapid and efficient proteolysis through laser-assisted immobilized enzyme reactors.

Science.gov (United States)

Zhang, Peng; Gao, Mingxia; Zhu, Shaochun; Lei, Jie; Zhang, Xiangmin

2011-11-25

In this report, laser radiation (808nm) for the first time was employed to enhance the efficiency of proteolysis through immobilized enzyme reactor (IMER). IMER based monolithic support was prepared in the fused-silica capillary via a simple two-step procedure including acryloylation on trypsin surface and in situ aqueous polymerization/immobilization. The feasibility and high efficiency of the laser-assisted IMER were demonstrated by the digestion of bovine serum albumin (BSA), cytochrome c (Cyt-c) and β-casein. The digestion process was achieved in 60s. The peptides were identified by MALDI-TOF-MS, yielding the sequence coverage of 33% for BSA, 73% for Cyt-c and 22% for β-casein. The comparisons between the in-solution digestion and on IMER reaction with/without laser assistance were made. To further confirm its efficiency in proteome analysis, the laser-assisted IMER was also applied to the analysis of one fraction of human serum sample through two-dimensional (2-D) separation of strong anion exchange/reversed-phase liquid chromatography (SAX/RPLC). After a database search, 49 unique peptides corresponding to 5 proteins were identified. The results showed that the laser-assisted IMER provides a promising platform for the high-throughput protein identification. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of protein degradation on spot Mr distribution in 2-D gels – a case study of proteolysis during development of Streptomyces coelicolor cultures

Czech Academy of Sciences Publication Activity Database

Vohradský, Jiří; Branny, Pavel; Li, X.-M.; Thompson, CH. J.

2008-01-01

Roč. 8, č. 12 (2008), s. 2371-2375 ISSN 1615-9853 R&D Projects: GA ČR GA310/07/1009 Grant - others:AT(AT) EC Integrated Project ActinoGEN, LSHM-CT-2004-005224 Institutional research plan: CEZ:AV0Z50200510 Keywords : 2-de * proteolysis * streptomyces Subject RIV: EE - Microbiology, Virology Impact factor: 4.586, year: 2008

Glucagon-like peptide 1: A potential anti-inflammatory pathway in obesity-related asthma.

Science.gov (United States)

Nguyen, Dan-Vinh; Linderholm, Angela; Haczku, Angela; Kenyon, Nicholas

2017-12-01

Alterations in arginine metabolism and accelerated formation of advanced glycation end-products (AGEs), crucial mechanisms in obesity-related asthma, can be modulated by glucagon-like peptide 1 (GLP-1). l-arginine dysregulation in obesity promotes inflammation and bronchoconstriction. Prolonged hyperglycemia, dyslipidemia, and oxidative stress leads to production of AGEs, that bind to their receptor (RAGE) further potentiating inflammation. By binding to its widely distributed receptor, GLP-1 blunts the effects of RAGE activation and arginine dysregulation. The GLP-1 pathway, while comprehensively studied in the endocrine and cardiovascular literature, is under-recognized in pulmonary research. Insights into GLP-1 and the lung may lead to novel treatments for obesity-related asthma. Published by Elsevier Inc.

Glutamine Triggers and Potentiates Glucagon-Like Peptide-1 Secretion by Raising Cytosolic Ca2+ and cAMP

OpenAIRE

Tolhurst, Gwen; Zheng, Yue; Parker, Helen E.; Habib, Abdella M.; Reimann, Frank; Gribble, Fiona M.

2011-01-01

L-glutamine stimulates glucagon-like peptide 1 (GLP-1) secretion in human subjects and cell lines. As recent advances have enabled the study of primary GLP-1–releasing L cells, this study aimed to characterize glutamine-sensing pathways in native murine L cells. L cells were identified using transgenic mice with cell-specific expression of fluorescent markers. Cells were studied in primary colonic cultures from adult mice, or purified by flow cytometry for expression analysis. Intracellular C...

PROTEOLYSIS DURING MANUFACTURE AND RIPENING/STORING OF “OLOMOUCKÉ TVARŮŽKY” CHEESE (PGI

Directory of Open Access Journals (Sweden)

Vendula Pachlová

2015-02-01

Full Text Available Twenty-two free amino acid (FAA concentrations were observed during manufacture (1st, 3rd and 7th days of production and ripening period (42 days storing at 8°C of “Olomoucké tvarůžky” (PGI, smear acid cheese. Sensory attributes were also analysed during ripening period. The free amino acids were determined by means of ion-exchange chromatography. The development of the individual FAA content positively correlated with the ripening period (r = 0.7734–0.9229; P < 0.01.The results gave information about the development precursors (FAA of typically sensory active compound in “Olomoucké tvarůžky” (PGI during its production and especially ripening. In conclusion, we found that free amino acid concentration as finally products of proteolysis are positive with improved flavour.

The amino acid transporters of the glutamate/GABA-glutamine cycle and their impact on insulin and glucagon secretion

Directory of Open Access Journals (Sweden)

Monica eJenstad

2013-12-01

Full Text Available Intercellular communication is pivotal in optimising and synchronising cellular responses to keep internal homeostasis and to respond adequately to external stimuli. In the central nervous system (CNS, glutamatergic and GABAergic signals are postulated to be dependent on the glutamate/GABA-glutamine (GGG cycle for vesicular loading of neurotransmitters, for inactivating the signal and for the replenishment of the neurotransmitters. Islets of Langerhans release the hormones insulin and glucagon, but share similarities with CNS cells in for example transcriptional control of development and differentiation, and chromatin methylation. Interestingly, proteins involved in the CNS in secretion of the neurotransmitters and emitting their responses as well as the regulation of these processes, are also found in islet cells. Moreover, high levels of glutamate, GABA and glutamine and their respective vesicular and plasma membrane transporters have been shown in the islet cells and there is emerging support for these amino acids and their transporters playing important roles in the maturation and secretion of insulin and glucagon. In this review, we will discuss the feasibility of recent data in the field in relation to the biophysical properties of the transporters (Slc1, Slc17, Slc32 and Slc38 and physiology of hormone secretion in islets of Langerhans.

Relative contribution of glycogenolysis and gluconeogenesis to basal, glucagon- and nerve stimulation-dependent glucose output in the perfused liver from fed and fasted rats

NARCIS (Netherlands)

Beuers, U.; JUNGERMANN, K.

1990-01-01

The relative contribution to basal, glucagon- and nerve stimulation-enhanced glucose output of glycogenolysis (glucose output in the presence of the gluconeogenic inhibitor mercaptopicolinate) and gluconeogenesis (difference in glucose output in the absence and presence of the inhibitor) was

Physiology of the endocrine pancreas.

Science.gov (United States)

Engelking, L R

1997-11-01

The endocrine pancreas is composed of nests of cells called the islets of Langerhans, which comprise only about 20% of pancreatic cell mass and secrete insulin, glucagon, somatostatin, and pancreatic polypeptide. Insulin is anabolic, increasing storage of glucose, fatty acids and amino acids, while glucagon namely stimulates hepatic glycogenolysis, gluconeogenesis, and ketogenesis. Somatostatin acts as a paracrine agent to inhibit both insulin and glucagon release, and, therefore, to modulate their output. This article explores factors controlling release of these hormones, as well as the way in which they affect fuel metabolism in the whole animal.

Functional Consequences of Glucagon-like Peptide-1 Receptor Cross-talk and Trafficking

DEFF Research Database (Denmark)

Roed, Sarah Noerklit; Nøhr, Anne Cathrine; Wismann, Pernille

2015-01-01

The signaling capacity of seven-transmembrane/G-protein-coupled receptors (7TM/GPCRs) can be regulated through ligand-mediated receptor trafficking. Classically, the recycling of internalized receptors is associated with resensitization, whereas receptor degradation terminates signaling. We have......) and glucagon (GCGR) receptors. The interaction and cross-talk between coexpressed receptors is a wide phenomenon of the 7TM/GPCR superfamily. Numerous reports show functional consequences for signaling and trafficking of the involved receptors. On the basis of the high structural similarity and tissue...... coexpression, we here investigated the potential cross-talk between GLP-1R and GIPR or GCGR in both trafficking and signaling pathways. Using a real-time time-resolved FRET-based internalization assay, we show that GLP-1R, GIPR, and GCGR internalize with differential properties. Remarkably, upon coexpression...

Multifunctional amaranth cystatin inhibits endogenous and digestive insect cysteine endopeptidases: A potential tool to prevent proteolysis and for the control of insect pests.

Science.gov (United States)

Valdés-Rodríguez, Silvia; Galván-Ramírez, Juan Pablo; Guerrero-Rangel, Armando; Cedro-Tanda, Alberto

2015-01-01

In a previous study, the amaranth cystatin was characterized. This cystatin is believed to provide protection from abiotic stress because its transcription is induced in response to heat, drought, and salinity. It has also been shown that recombinant amaranth cystatin inhibits bromelain, ficin, and cysteine endopeptidases from fungal sources and also inhibits the growth of phytopathogenic fungi. In the present study, evidence is presented regarding the potential function of amaranth cystatin as a regulator of endogenous proteinases and insect digestive proteinases. During amaranth germination and seedling growth, different proteolytic profiles were observed at different pH levels in gelatin-containing SDS-PAGE. Most of the proteolytic enzymes detected at pH 4.5 were mainly inhibited by trans-epoxysuccinyl-leucyl amido(4-guanidino)butane (E-64) and the purified recombinant amaranth cystatin. Furthermore, the recombinant amaranth cystatin was active against insect proteinases. In particular, the E-64-sensitive proteolytic digestive enzymes from Callosobruchus maculatus, Zabrotes subfasciatus, and Acanthoscelides obtectus were inhibited by the amaranth cystatin. Taken together, these results suggest multiple roles for cystatin in amaranth, specifically during germination and seedling growth and in the protection of A. hypochondriacus against insect predation. Amaranth cystatin represents a promising tool for diverse applications in the control of insect pest and for preventing undesirable proteolytic activity. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Glucagon-like peptide-1 (GLP-1) raises blood-brain glucose transfer capacity and hexokinase activity in human brain

OpenAIRE

Gejl, Michael; Lerche, Susanne; Egefjord, L?rke; Brock, Birgitte; M?ller, Niels; Vang, Kim; Rodell, Anders B.; Bibby, Bo M.; Holst, Jens J.; Rungby, J?rgen; Gjedde, Albert

2013-01-01

In hyperglycemia, glucagon-like peptide-1 (GLP-1) lowers brain glucose concentration together with increased net blood-brain clearance and brain metabolism, but it is not known whether this effect depends on the prevailing plasma glucose (PG) concentration. In hypoglycemia, glucose depletion potentially impairs brain function. Here, we test the hypothesis that GLP-1 exacerbates the effect of hypoglycemia. To test the hypothesis, we determined glucose transport and consumption rates in seven h...

Tissue and plasma concentrations of amidated and glycine-extended glucagon-like peptide I in humans

DEFF Research Database (Denmark)

Orskov, C; Rabenhøj, L; Wettergren, A

1994-01-01

Using specific radioimmunoassays, we studied the occurrence of amidated and glycine-extended glucagon-like peptide I (GLP-I) molecules in the human small intestine and pancreas and in the circulation system in response to a breakfast meal. Through gel permeation chromatography of extracts...... plasma were 7 +/- 1 and 6 +/- 1 pM, respectively (n = 6). In response to a breakfast meal, the concentration of amidated GLP-I rose significantly amounting to 41 +/- 5 pM 90 min after the meal ingestion, whereas the concentration of glycine-extended GLP-I only rose slightly to a maximum of 10 +/- 1 p...

Small Molecule Drug Discovery at the Glucagon-Like Peptide-1 Receptor

Directory of Open Access Journals (Sweden)

Francis S. Willard

2012-01-01

Full Text Available The therapeutic success of peptide glucagon-like peptide-1 (GLP-1 receptor agonists for the treatment of type 2 diabetes mellitus has inspired discovery efforts aimed at developing orally available small molecule GLP-1 receptor agonists. Although the GLP-1 receptor is a member of the structurally complex class B1 family of GPCRs, in recent years, a diverse array of orthosteric and allosteric nonpeptide ligands has been reported. These compounds include antagonists, agonists, and positive allosteric modulators with intrinsic efficacy. In this paper, a comprehensive review of currently disclosed small molecule GLP-1 receptor ligands is presented. In addition, examples of “ligand bias” and “probe dependency” for the GLP-1 receptor are discussed; these emerging concepts may influence further optimization of known molecules or persuade designs of expanded screening strategies to identify novel chemical starting points for GLP-1 receptor drug discovery.

Glucagon-like peptide-1 decreases intracerebral glucose content by activating hexokinase and changing glucose clearance during hyperglycemia

DEFF Research Database (Denmark)

Gejl, Michael; Egefjord, Lærke; Lerche, Susanne

2012-01-01

Type 2 diabetes and hyperglycemia with the resulting increase of glucose concentrations in the brain impair the outcome of ischemic stroke, and may increase the risk of developing Alzheimer's disease (AD). Reports indicate that glucagon-like peptide-1 (GLP-1) may be neuroprotective in models of AD...... in the actions of GLUT1 and glucose metabolism: GLP-1 ensures less fluctuation of brain glucose levels in response to alterations in plasma glucose, which may prove to be neuroprotective during hyperglycemia....

Chenodeoxycholic acid stimulates glucagon-like peptide-1 secretion in patients after Roux-en-Y gastric bypass

DEFF Research Database (Denmark)

Nielsen, Signe; Svane, Maria S; Kuhre, Rune E

2017-01-01

(BMI 29.1 ± 1.2, age 37.0 ± 3.2 years, time from RYGB 32.3 ± 1.1 months, weight loss after RYGB 37.0 ± 3.1 kg) were studied in a placebo-controlled, crossover-study. On three different days, participants ingested (1) placebo (water), (2) UDCA 750 mg, (3) CDCA 1250 mg (highest recommended doses). Oral...... intake of CDCA increased plasma concentrations of GLP-1, C-peptide, glucagon, peptide YY, neurotensin, total bile acids, and fibroblast growth factor 19 significantly compared with placebo (all P

Modulation of the sympathetic nerve action on carbohydrate and ketone body metabolism by fatty acids, glucagon und insulin in perfused rat liver

NARCIS (Netherlands)

Küster, J.; Beuers, U.; JUNGERMANN, K.

1989-01-01

Rat liver was perfused in situ via the portal vein without recirculation: 1) Nerve stimulation (20 Hz, 2 ms, 20 V) increased glucose output and shifted lactate uptake to output; the alterations were diminished by oleate but not octanoate. 2) Glucagon (1nM) stimulated glucose output maximally also in

Simultaneous delivery of antibiotics neomycin and ampicillin in drinking water inhibits fermentation of resistant starch in rats.

Science.gov (United States)

Carvajal-Aldaz, Diana G; Guice, Justin L; Page, Ryan C; Raggio, Anne M; Martin, Roy J; Husseneder, Claudia; Durham, Holiday A; Geaghan, James; Janes, Marlene; Gauthier, Ted; Coulon, Diana; Keenan, Michael J

2017-03-01

Antibiotics ampicillin 1 g/L and neomycin 0.5 g/L were added to drinking water before or during feeding of resistant starch (RS) to rats to inhibit fermentation. In a preliminary study, antibiotics and no RS were given prior to rats receiving a transplant of cecal contents via gavage from donor rats fed RS (without antibiotics) or a water gavage before feeding resistant starch to both groups. Antibiotics given prior to feeding RS did not prevent later fermentation of RS regardless of either type of gavage. In the second study, antibiotics were given simultaneously with feeding of RS. This resulted in inhibition of fermentation of RS with cecal contents pH >8 and low amounts of acetate and butyrate. Rats treated with antibiotics had reduced Bifidobacteria spp., but similar Bacteroides spp. to control groups to reduce acetate and butyrate and preserve the production of propionate. Despite reduced fermentation, rats given antibiotics had increased glucagon-like peptide 1 (GLP-1) and cecum size, measures that are usually associated with fermentation. A simultaneous delivery of antibiotics inhibited fermentation of RS. However, increased GLP-1 and cecum size would be confounding effects in assessing the mechanism for beneficial effects of dietary RS by knocking out fermentation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exaggerated release and preserved insulinotropic action of glucagon-like peptide-1 underlie insulin hypersecretion in glucose-tolerant individuals after Roux-en-Y gastric bypass

DEFF Research Database (Denmark)

Dirksen, Carsten; Bojsen-Møller, Kirstine N; Jørgensen, Nils Bruun

2013-01-01

Roux-en-Y gastric bypass (RYGB) improves glycaemic control in part by increasing postprandial insulin secretion through exaggerated glucagon-like peptide (GLP)-1 release. However, it is unknown whether islet cell responsiveness to i.v. glucose, non-glucose (arginine) and incretin hormones...

The glucagon-like peptide-1 metabolite GLP-1-(9-36) amide reduces postprandial glycemia independently of gastric emptying and insulin secretion in humans

DEFF Research Database (Denmark)

Meier, Juris J; Gethmann, Arnica; Nauck, Michael A

2006-01-01

Glucagon-like peptide 1 (GLP-1) lowers glycemia by modulating gastric emptying and endocrine pancreatic secretion. Rapidly after its secretion, GLP-1-(7-36) amide is degraded to the metabolite GLP-1-(9-36) amide. The effects of GLP-1-(9-36) amide in humans are less well characterized. Fourteen...... healthy volunteers were studied with intravenous infusion of GLP-1-(7-36) amide, GLP-1-(9-36) amide, or placebo over 390 min. After 30 min, a solid test meal was served, and gastric emptying was assessed. Blood was drawn for GLP-1 (total and intact), glucose, insulin, C-peptide, and glucagon measurements....... Administration of GLP-1-(7-36) amide and GLP-1-(9-36) amide significantly raised total GLP-1 plasma levels. Plasma concentrations of intact GLP-1 increased to 21 +/- 5 pmol/l during the infusion of GLP-1-(7-36) amide but remained unchanged during GLP-1-(9-36) amide infusion [5 +/- 3 pmol/l; P

Angioplastic necrolytic migratory erythema. Unique association of necrolytic migratory erythema, extensive angioplasia, and high molecular weight glucagon-like polypeptide

International Nuclear Information System (INIS)

Franchimont, C.; Pierard, G.E.; Luyckx, A.S.; Gerard, J.; Lapiere, C.M.

1982-01-01

A diabetic patient developed necrolytic migratory erythema with extensive angioplasia and high molecular weight glucagon-like polypeptide. There was no associated neoplasm such as glucagonoma. Lesions in the skin were studied by standard optical microscopy and by radioautography after incorporation of tritiated thymidine. Alterations in the skin begin as focal necrosis in the epidermis and in epithelial structures of adnexa, followed by marked angioplasia and a superficial and deep perivascular dermatitis

Initiation of proteolysis of yeast fructose-1,6-bisphosphatase by pH-control of adenylate cyclase

International Nuclear Information System (INIS)

Holzer, H.; Purwin, C.; Pohlig, G.; Scheffers, W.A.; Nicolay, K.

1986-01-01

Addition of fermentable sugars or uncouplers such as CCCP to resting yeast cells grown on glucose initiates phosphorylation of fructose-1,6-bisphosphatase (FBPase). There is good evidence that phosphorylation marks FBPase for proteolytic degradation. 31 P-NMR measurements of the cytosolic pH of yeast cells demonstrated a decrease of the cytosolic pH from 7.0 to 6.5 after addition of glucose or CCCP to starved yeast. Activity of adenylate cyclase in permeabilized yeast cells increases 2-3-fold when the pH is lowered from 7.0 to 6.5. It is concluded that pH controlled activation of adenylate cyclase causes the previously described increase in cyclic AMP which leads to phosphorylation of FBPase and finally to proteolysis of FBPase

VEGFR2 Trafficking, Signaling and Proteolysis is Regulated by the Ubiquitin Isopeptidase USP8.

Science.gov (United States)

Smith, Gina A; Fearnley, Gareth W; Abdul-Zani, Izma; Wheatcroft, Stephen B; Tomlinson, Darren C; Harrison, Michael A; Ponnambalam, Sreenivasan

2016-01-01

Vascular endothelial growth factor A (VEGF-A) regulates many aspects of vascular function. VEGF-A binding to vascular endothelial growth factor receptor 2 (VEGFR2) stimulates endothelial signal transduction and regulates multiple cellular responses. Activated VEGFR2 undergoes ubiquitination but the enzymes that regulate this post-translational modification are unclear. In this study, the de-ubiquitinating enzyme, USP8, is shown to regulate VEGFR2 trafficking, de-ubiquitination, proteolysis and signal transduction. USP8-depleted endothelial cells displayed altered VEGFR2 ubiquitination and production of a unique VEGFR2 extracellular domain proteolytic fragment caused by VEGFR2 accumulation in the endosome-lysosome system. In addition, perturbed VEGFR2 trafficking impaired VEGF-A-stimulated signal transduction in USP8-depleted cells. Thus, regulation of VEGFR2 ubiquitination and de-ubiquitination has important consequences for the endothelial cell response and vascular physiology. © 2015 The Authors. Traffic published by John Wiley & Sons Ltd.

Bioactivity of a modified human Glucagon-like peptide-1.

Directory of Open Access Journals (Sweden)

Fangfang Xu

Full Text Available Diabetes has become the third largest cause of death in humans worldwide. Therefore, effective treatment for this disease remains a critical issue. Glucagon-like peptide-1 (GLP-1 plays an important role in glucose homeostasis, and therefore represents a promising candidate to use for the treatment of diabetes. Native GLP-1, however, is quickly degraded in in the circulatory system; which limits its clinical application. In the present study, a chemically-synthesized, modified analogue of human GLP-1 (mGLP-1 was designed. Our analyses indicated that, relative to native GLP-1, mGLP-1 is more resistant to trypsin and pancreatin degradation. mGLP-1 promotes mouse pancreatic β-cell proliferation by up-regulating the expression level of cyclin E, CDK2, Bcl-2 and down-regulating Bax, p21, and stimulates insulin secretion. An oral glucose tolerance test indicated that mGLP-1 significantly improved glucose tolerance in mice. Intraperitoneal injections of mGLP-1 into streptozotocin (STZ-induced type 2 diabetic mice significantly reduced blood sugar levels and stimulated insulin secretion. Oral gavages of mGLP-1 in diabetic mice did not result in significant hypoglycemic activity.

A cytosolic protein factor from the naked mole-rat activates proteasomes of other species and protects these from inhibition

Science.gov (United States)

Rodriguez, Karl A.; Osmulski, Pawel A.; Pierce, Anson; Weintraub, Susan T.; Gaczynska, Maria; Buffenstein, Rochelle

2015-01-01

The naked mole-rat maintains robust proteostasis and high levels of proteasome-mediated proteolysis for most of its exceptional (~31y) life span. Here, we report that the highly active proteasome from the naked mole-rat liver resists attenuation by a diverse suite of proteasome-specific small molecule inhibitors. Moreover, mouse, human, and yeast proteasomes exposed to the proteasome-depleted, naked mole-rat cytosolic fractions, recapitulate the observed inhibition resistance, and mammalian proteasomes also show increased activity. Gel filtration coupled with mass spectrometry and atomic force microscopy indicates that these traits are supported by a protein factor that resides in the cytosol. This factor interacts with the proteasome and modulates its activity. Although HSP72 and HSP40 (Hdj1) are among the constituents of this factor, the observed phenomenon, such as increasing peptidase activity and protecting against inhibition cannot be reconciled with any known chaperone functions. This novel function may contribute to the exceptional protein homeostasis in the naked mole-rat and allow it to successfully defy aging. PMID:25018089

Fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and urinary C-peptide in relation to clinical type of diabetes

DEFF Research Database (Denmark)

Gjessing, H J; Matzen, L E; Faber, O K

1989-01-01

with a fasting plasma C-peptide value less than 0.20 nmol/l, a glucagon stimulated plasma C-peptide value less than 0.32 nmol/l, and a urinary C-peptide value less than 3.1 nmol/l, or less than 0.54 nmol/mmol creatinine/24 h, or less than 5.4 nmol/24 h mainly were Type 1 diabetic patients; while patients with C...

Continuous subcutaneous infusion of glucagon-like peptide 1 lowers plasma glucose and reduces appetite in type 2 diabetic patients

DEFF Research Database (Denmark)

Toft-Nielsen, M B; Madsbad, Sten; Holst, J J

1999-01-01

OBJECTIVE: The gut hormone glucagon-like peptide 1 (GLP-1) has insulinotropic and anorectic effects during intravenous infusion and has been proposed as a new treatment for type 2 diabetes and obesity. The effect of a single subcutaneous injection is brief because of rapid degradation. We therefo....... CONCLUSIONS: We conclude that 48-h continuous subcutaneous infusion of GLP-1 in type 2 diabetic patients 1) lowers fasting as well as meal-related plasma glucose, 2) reduces appetite, 3) has no gastrointestinal side effects, and 4) has no negative effect on blood pressure.......OBJECTIVE: The gut hormone glucagon-like peptide 1 (GLP-1) has insulinotropic and anorectic effects during intravenous infusion and has been proposed as a new treatment for type 2 diabetes and obesity. The effect of a single subcutaneous injection is brief because of rapid degradation. We therefore......, previously shown to lower blood glucose effectively in type 2 diabetic patients. Fasting plasma glucose (day 2) decreased from 14.1 +/- 0.9 (saline) to 12.2 +/- 0.7 mmol/l (GLP-1), P = 0.009, and 24-h mean plasma glucose decreased from 15.4 +/- 1.0 to 13.0 +/- 1.0 mmol/l, P = 0.0009. Fasting and total area...

Treatment of type 2 diabetes with glucagon-like peptide-1 receptor agonists

DEFF Research Database (Denmark)

Hansen, K B; Knop, F K; Holst, Jens Juul

2009-01-01

of hypoglycaemia with GLP-1 receptor agonists is low, the compounds have clinically relevant effects on body weight, and data are suggesting beneficial effects on cardiovascular risk factors. Exenatide was released in 2005 for the treatment of type 2 diabetes and liraglutide is expected to be approved by the Food......The incretin system is an area of great interest for the development of new therapies for the management of type 2 diabetes. Existing antidiabetic drugs are often insufficient at getting patients to glycaemic goals. Furthermore, current treatment modalities are not able to prevent the continued...... ongoing decline in pancreatic beta-cell function and, lastly, they have a number of side effects including hypoglycaemia and weight gain. Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of pharmacological agents, which improve glucose homeostasis in a multifaceted way. Their effects...

Secretion of glucagon-like peptide-1 (GLP-1) in type 2 diabetes

DEFF Research Database (Denmark)

Nauck, M A; Vardarli, I; Deacon, C F

2011-01-01

The incretin hormones gastric inhibitory polypeptide and especially glucagon-like peptide (GLP) have an important physiological function in augmenting postprandial insulin secretion. Since GLP-1 may play a role in the pathophysiology and treatment of type 2 diabetes, assessment of meal-related GLP......-1 secretory responses in type 2 diabetic patients vs healthy individuals is of great interest. A common view states that GLP-1 secretion in patients with type 2 diabetes is deficient and that this applies to a lesser degree in individuals with impaired glucose tolerance. Such a deficiency...... with and without diabetes after oral glucose and mixed meals. Our analysis does not support the contention of a generalised defect in nutrient-related GLP-1 secretory responses in type 2 diabetes patients. Rather, factors are identified that may determine individual incretin secretory responses and explain some...