Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Type I diabetes is characterized by the deficiency of endocrine beta cells in the pancreatic islets of Langerhans and transplantation of islet cells can be an effective therapeutic approach. Embryonic stem cells can be differentiated into any cell type, and therefore represent an unlimited source of islet cells for the transplantation and treatment for type I diabetes. We have adopted an easy and reproducible in vitro differentiation system with a reduced serum concentration plus nicotinamide to generate early pancreatic progenitor cells from embryonic stem cells. Gene expression analysis indicated that the differentiated cells expressed not only endoderm markers such as GATA-4, HNF-3beta, but also early markers of pancreatic development including key transcription factors PDX-1 and IAPP. Some pancreatic specific markers, such as insulin I, insulin II, Glu-2 and glucagon, were also expressed to some extent at the mRNA level. Differentiated ES cells showed low level immunoreactivity for insulin. However, transplantation of these early pancreatic progenitor clusters into STZ-induced diabetic mice failed to reverse the hyperglycemic state of the disease as reported previously. The results suggest that culture manipulation can direct ES cells to differentiate into early pancreatic progenitor cells committing to pancreatic islet cell fate, but these cells cannot function normally to reduce blood glucose of diabetic mice at this stage.
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PMID:Differentiation of embryonic stem cells towards pancreatic progenitor cells and their transplantation into streptozotocin-induced diabetic mice. 1827 10

Dipeptidyl peptidase (DPP)-IV inhibitors are expected to become a useful new class of antidiabetic agent. The aim of the present study is to characterize the in vitro and in vivo profile of ASP8497, (2S,4S)-4-fluoro-1-({[4-methyl-1-(methylsulfonyl)piperidin-4-yl]amino}acetyl)pyrrolidine-2-carbonitrile monofumarate, which is a novel DPP-IV inhibitor. ASP8497 inhibited DPP-IV in plasma from mice, rats, dogs and humans with IC(50) values of 3.86, 2.36, 5.53 and 5.30 nM, respectively. In contrast, ASP8497 did not potently inhibit DPP8 or DPP9 activity (IC(50)>200 nM). Kinetic analysis indicated that ASP8497 inhibits DPP-IV activity in a competitive manner. In streptozotocin-nicotinamide-induced diabetic mice, ASP8497 (3 mg/kg) significantly reduced glucose excursion during the oral glucose tolerance test conducted 0.5 and 8.5 h after administration, with increases in plasma insulin and active glucagon-like peptide-1 (GLP-1) levels. In contrast, ASP8497 (3 and 30 mg/kg) did not cause hypoglycemia in fasted normal mice. Furthermore, administration of exogenous GLP-1 induced significant inhibition of gastric emptying and small intestinal transit rates, but ASP8497 (30 mg/kg) had no significant effects in normal mice. These present preclinical studies indicate that ASP8497 is a novel selective DPP-IV inhibitor with long-acting antidiabetic effect that might be a potential agent for type 2 diabetes.
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PMID:ASP8497 is a novel selective and competitive dipeptidyl peptidase-IV inhibitor with antihyperglycemic activity. 1846 82

A major obstacle to successful islet transplantation for both type 1 and 2 diabetes is an inadequate supply of insulin-producing tissue. In vitro transdifferentiation of human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) into insulin-producing cells could provide an abundant source of cells for this procedure. For this study, we isolated and characterized human UCB-MSCs and induced them in vitro to differentiate into islet-like cell clusters using a 15-day protocol based on a combination of high-glucose, retinoic acid, nicotinamide, epidermal growth factor, and exendin-4. These clusters appeared about 9 days after pancreatic differentiation; expressed pancreatic beta-cell markers, including insulin, glucagon, Glut-2, PDX1, Pax4, and Ngn3; and could synthesize and secrete functional islet proteins at the end of the inducing protocol. The insulin-positive cells accounted for (25.2-3.36)% of whole induced cells. Although insulin secretion of those insulin-producing cells did not respond to glucose challenge very well, human UCB-MSCs have the ability to differentiate into islet-like cells in vitro and may be a potential new source for islet transplantation.
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PMID:In vitro cultivation of islet-like cell clusters from human umbilical cord blood-derived mesenchymal stem cells. 1851 40

The major obstacle in using pancreatic islet transplantation to cure type I and some type II diabetes is the shortage of the donors. One of ways to overcome such obstacle is to isolate and clone pancreatic stem cells as "seed cells" and induce their differentiation into functional islets as an abundant transplantation source. In this study, a monoclonal human pancreatic stem cell (mhPSC) line was obtained from abortive fetal pancreatic tissues. Pancreatic tissues were taken from abortive fetus by sterile procedures, and digested into single cells and cell clusters with 0.1% type IV collagenase. Cultured in modified glucose-low DMEM with 10% fetal bovine serum (FBS), these single cells and cell clusters adhered to culture dishes, and then primary epidermal-like pancreatic stem cells started to clone. After digesting with 0.25% trypsin and 0.04% EDTA, fibroblasts and other cells were gradually eliminated and epithelioid pancreatic stem cells were gradually purified during generations. Using clone-ring selection, the mhPSCs were obtained. After addition of 10 ng/mL epidermal growth factor (EGF) in cell culture medium, the mhPSCs quickly grew and formed a gravelstone-like monolayer. Continuously proliferated, a mhPSC line, which was derived from a male abortive fetus of 4 months old, has been passed through 50 generations. More than 1 x 10(9) mhPSCs were cryo-preserved in liquid nitrogen. Karyotype analysis showed that the chromosome set of the mhPSC line was normal diploid. Immunocytochemistry results demonstrated that the mhPSC line was positive for the pdx1, glucagon, nestin and CK19, and negative for the insulin, CD34, CD44 and CD45 protein expression. RT-PCR revealed further that the mhPSCs expressed transcription factors of the pdx1, glucagon, nestin and CK19. Also, in vitro induced with beta-mercaptoethanol, the mhPSCs differentiated into nerve cells that expressed the NF protein. Induced with nicotinamide, the mhPSCs differentiated into functional islet-like clusters, as identified by dithizone staining, which expressed the transcription factor of the insulin and secreted the insulin and C-peptide. Furthermore, the transplantation of mhPSCs-induced pancreatic islets into the subcapsular region of the kidney in streptozotocin-induced diabetic rats could reduce blood glucose levels and prolong the life time.
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PMID:Establishing a human pancreatic stem cell line and transplanting induced pancreatic islets to reverse experimental diabetes in rats. 1872 23

Islet-like cells derived from embryonic stem (ES) cells may be a promising therapeutic option for future diabetes treatment. Here, we demonstrated a five-stage protocol with adding exendin-4 instead of nicotinamide finally could generate islet-like cells from human embryonic stem (ES) cells. Immunofluorescence analysis revealed a high percentage of c-peptide positive cells in the derivation. However, in addition to insulin/c-peptide, most cells also coexpressed PDX-1 (pancreas duodenum homeobox-1), glucagon, somatostatin or pancreatic polypeptide. Insulin and other pancreatic beta-cell-specific genes were all present in the differentiated cells. Insulin secretion could be detected and increased significantly by adding KCL in high glucose concentration in vitro. Furthermore, subcutaneous transplantation of scaffolds seeded with the islet-like cells or cell transplantation under kidney capsules for further differentiation in vivo could improve 6h fasted blood glucose levels and diabetic phenotypes in streptozotocin-induced diabetic SCID mice. More interestingly, blood vessels of host origin, characterized by mouse CD31 immunostaining, invaded the cell-scaffold complexes. This work reveals a five-stage protocol with adding exendin-4 may be an effective protocol on the differentiation of human ES cells into islet-like cells, and suggests scaffolds can serve as vehicles for islet-like cell transplantation.
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PMID:The reversal of hyperglycaemia in diabetic mice using PLGA scaffolds seeded with islet-like cells derived from human embryonic stem cells. 1913 50

Gastrointestinal hormone glucagon-like peptide-1 (GLP-1) has a potent glucose-dependent insulinotropic effect and is rapidly degraded by dipeptidyl peptidase (DPP)-IV. Therefore, the use of DPP-IV inhibitors is being actively explored as a novel approach to the treatment of type 2 diabetes. The present study investigated the antidiabetic effects of the DPP-IV inhibitor ASP8497 in streptozotocin-nicotinamide-induced mildly diabetic mice which possess aggravation of glucose tolerance due to loss of early-phase insulin secretion. ASP8497 exhibited good oral bioavailability with potent inhibition of plasma DPP-IV activity. This inhibitory activity lasted up to 24 h when administered at 5 mg/kg twice a day or 10 mg/kg once a day. A single oral administration of ASP8497 (0.3-3 mg/kg) significantly improved glucose tolerance by increasing plasma insulin and GLP-1 levels during the oral glucose or liquid meal tolerance tests. These effects were seen not only immediately, but also 8 h after administration. In contrast, ASP8497 (0.3-10 mg/kg) had no significant effect on blood glucose and plasma insulin levels under fasting conditions. Furthermore, repeated administration of ASP8497 (5 mg/kg twice a day or 10 mg/kg once a day) for 25 days significantly decreased nonfasting blood glucose and HbA(1c) levels. These results suggest that ASP8497 is a potent and long-acting DPP-IV inhibitor that improves glucose tolerance through glucose-dependent insulinotropic action via the elevation of the GLP-1 level in streptozotocin-nicotinamide-induced mildly diabetic mice. It is expected to be useful as a therapeutic agent for impaired glucose tolerance and type 2 diabetes.
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PMID:Evaluation of the antidiabetic effects of dipeptidyl peptidase-IV inhibitor ASP8497 in streptozotocin-nicotinamide-induced mildly diabetic mice. 1917 82

The present study investigated the antidiabetic effects of the dipeptidyl peptidase (DPP)-IV inhibitors ASP8497 and vildagliptin, and the sulfonylureas glibenclamide and gliclazide in streptozotocin-nicotinamide-induced mildly diabetic mice. A single administration of ASP8497 and vildagliptin significantly improved glucose tolerance by increasing plasma insulin and glucagon-like peptide-1 levels. In addition, a single administration of glibenclamide and gliclazide also caused significant improvement in glucose tolerance with an accompanying increase in the plasma insulin level. Subsequently, the effects of a 1-week chronic daily dosing of DPP-IV inhibitors and sulfonylureas were investigated. All drugs significantly improved glucose tolerance on day 1 of chronic daily dosing. After 1 week of chronic daily dosing, the DPP-IV inhibitors caused a significant improvement in glucose tolerance similar to those observed on day 1 by increasing the plasma insulin and glucagon-like peptide-1 levels. In contrast, the sulfonylureas had no significant improving or insulinotropic effect. Furthermore, ASP8497 also had an antihyperglycemic effect and improved pancreatic histopathologic lesions in a 4-week chronic daily dosing study. These results suggest that chronic daily dosing of sulfonylureas had virtually no antidiabetic effects because of marked attenuation of the insulinotropic action in streptozotocin-nicotinamide-induced mildly diabetic mice. In contrast, the antidiabetic efficacy of DPP-IV inhibitors, including ASP8497, did not change even after chronic daily dosing; therefore, DPP-IV inhibitors are useful as a therapeutic agent for impaired glucose tolerance and type 2 diabetes mellitus.
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PMID:Antidiabetic effects of dipeptidyl peptidase-IV inhibitors and sulfonylureas in streptozotocin-nicotinamide-induced mildly diabetic mice. 1921 55

Fasting hyperglycemia in patients with type 2 diabetes mellitus (T2DM) is attributed to increased hepatic gluconeogenesis, which has been ascribed to increased transcriptional expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase, catalytic (G6Pc). To test this hypothesis, we examined hepatic expression of these 2 key gluconeogenic enzymes in 2 rodent models of fasting hyperglycemia and in patients with T2DM. In rats, high-fat feeding (HFF) induces insulin resistance but a robust beta-cell response prevents hyperglycemia. Fasting hyperglycemia was induced in the first rat model by using nicotinamide and streptozotocin to prevent beta-cell compensation, in combination with HFF (STZ/HFF). In a second model, control and HFF rats were infused with somatostatin, followed by portal vein infusion of insulin and glucagon. Finally, the expression of these enzymes was measured in liver biopsy samples obtained from insulin sensitive, insulin resistant, and untreated T2DM patients undergoing bariatric surgery. Rats treated with STZ/HFF developed modest fasting hyperglycemia (119 +/- 4 vs. 153 +/- 6 mg/dL, P < 0.001) and increased rates of endogenous glucose production (EGP) (4.6 +/- 0.6 vs. 6.9 +/- 0.6 mg/kg/min, P = 0.02). Surprisingly, the expression of PEPCK or G6Pc was not increased. Matching plasma insulin and glucagon with portal infusions led to higher plasma glucoses in the HFF rats (147 +/- 4 vs. 161 +/- 4 mg/dL, P = 0.05) with higher rates of EGP and gluconeogenesis. However, PEPCK and G6Pc expression remained unchanged. Finally, in patients with T2DM, hepatic expression of PEPCK or G6Pc was not increased. Thus, in contrast to current dogma, these data demonstrate that increased transcriptional expression of PEPCK1 and G6Pc does not account for increased gluconeogenesis and fasting hyperglycemia in patients with T2DM.
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PMID:Fasting hyperglycemia is not associated with increased expression of PEPCK or G6Pc in patients with Type 2 Diabetes. 1958 43

Pyridoxal phosphate and pyridoxamine phosphate, the catalytically active forms of vitamin B(6), influence brain function by participating at stages in metabolism of proteins, lipids, carbohydrates, other coenzymes and hormones. Vitamin B(6) participates in the metabolism of amino acids in the form of decarboxylation, transamination, deamination, racemization and desulfhydration reactions. The crucial roles that these coenzymes play in the maintenance of functional integrity of the brain become evident when one realizes that some compounds implicated as neurotransmitters are synthesized and/or metabolized by the aid of the vitamin B(6)-dependent enzymatic reactions. These include dopamine, norepinephrine and serotonin, tyramine, tryptamine, taurine, histamine, gamma aminobutyric acid, and even acetylcholine indirectly. In recent years, the above-mentioned biogenic amines have become of considerable interest to neurobiologists who are investigating the etiology and the pathological manifestations of many disorders of the central nervous system such as Parkinsonism, Huntington's chorea, minimal brain disfunction, schizophrenia, depression, sleep disorders and seizure disorders. Vitamin B(6) deficiency in these cases is characterized by anemia, growth retardation and alteration in neuronal function, including neuropathies, hyperirritability, hyperexcitability and convulsions. The importance of vitamin B(6) in the study of brain function assumes still greater significance when one considers the effects of nutritional deficiencies on growth and development of the brain and mental processes and in the involvement of vitamin B(6) in some inborn errors of metabolism which result in mental retardation. Vitamin B(6) deficiency results in a lowered concentration of Coenzyme A in blood, in reduced absorption and storage of vitamin B(12), and in increased excretion of vitamin C. Furthermore, vitamin B(6) acts synergistically with vitamin E to control metabolism of unsaturated fats, with vitamin C in tyrosine metabolism and with niacin in its action and participates in niacin synthesis. In addition, vitamin B(6) deficiency results in insufficiency of insulin and in alteration of the functions of adrenal and pituitary glands, since it is involved in the synthesis of growth hormone, follicle-stimulating hormone, luteinizing hormone, aldosterone, glucagon, cortisol, estradiol, testosterone and epinephrine. It is hoped that by understanding the factors that regulate the synthesis, binding, storage and degradation of pyridoxal phosphate in the brain, a better insight into the role of vitamin B(6) in neurobiology may be gained.
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PMID:Regulation and function of pyridoxal phosphate in CNS. 1964 63

The aim of the work described here was to improve our understanding of beta-cell function (BCF) and beta-cell mass (BCM) and their relationship in vivo using the minipig as a model for some of the aspects of human type 2 diabetes (T2DM). More specifically, the aim was to evaluate the following questions: How is BCF, especially high frequency pulsatile insulin secretion, affected by a primary reduction in BCM or by primary obesity or a combination of the two in the minipig? Can evaluation of BCF in vivo be used as a surrogate measure to predict BCM in minipigs over a range of BCM and body weight? We first developed a minipig model of reduced BCM and mild diabetes using administration of a combination of streptozotocin (STZ) and nicotinamide (NIA) as a tool to study effects of a primary reduction of BCM on BCF. The model was characterized using a mixed-meal oral glucose tolerance test and intravenous stimulation with glucose and arginine as well as by histology of the pancreas after euthanasia. It was shown that stable, moderate diabetes can be induced and that the model is characterized by fasting and postprandial hyperglycemia, reduced insulin secretion and reduced BCM. Several defects in insulin secretion are well documented in human T2DM; however, the role in the pathogenesis and the possible clinical relevance of high frequency (rapid) pulsatile insulin secretion is still debated. We therefore investigated this phenomenon in normal minipigs and found easily detectable pulses in peripheral vein plasma samples that were shown to be correlated with pulses found in portal vein plasma. Furthermore, the rapid kinetics of insulin in the minipig strongly facilitates pulse detection. These characteristics make the minipig particularly suitable for studying the occurrence of disturbed pulsatility in relation to T2DM. Disturbances of rapid pulsatile insulin secretion have been reported to be a very early event in the development of T2DM and include disorderliness of pulses and reduced ability to entrain pulses with glucose. However, the role of reduced BCM and/or obesity in the development of these defects in humans is unknown. Therefore, the investigations were extended to include lean NIA/STZ minipigs where it was shown that a primary reduction of BCM leads to reduced insulin pulse mass but does not change periodicity of the pulses or the ability of glucose to entrain pulses. In contrast, obesity was found to be associated with reduced pulsatile insulin secretion and improved orderliness of glucose entrained pulses in the minipig. Furthermore obesity was associated with pancreatic lipid accumulation and increased beta-cell volume, although BCM relative to body weight was not changed. Finally, a combination of obesity and reduced BCM resulted in severely disturbed insulin secretion and severe morphological changes. Thus, results from NIA/STZ minipigs suggest that not all of the defects of rapid pulsatile insulin secretion seen in human T2DM can be explained by a primary reduction of BCM mass or up to 2 weeks of mild hyperglycemia. Furthermore, based on the results from obese minipigs, obesity in itself induces small defects in rapid pulsatile insulin secretion and the combination of obesity and reduced BCM leads to further deterioration of BCF. Another major characteristic of human diabetes is thought to be reduction of BCM and the ability to follow this parameter over time would greatly improve our understanding of disease progression and allow evaluation of pharmacological methods to increase BCM. BCM cannot, at present, be measured in vivo in humans. We therefore set out to further validate data from smaller studies in lean non-human primates and minipigs showing a correlation between measures of BCF in vivo and BCM. In a large study in lean minipigs with a range of BCM, we found that a strong stimulation of insulin secretion with a combination of glucose and arginine resulted in the best correlation to BCM, as determined using stereology. A similar relationship was also shown in a group of both lean and obese animals, thereby supporting the application of similar methods to estimate BCM in humans over a range of body weights. Since changes in rapid pulsatile insulin secretion are detectable early in the development of diabetes and in obesity, we hypothesized that this parameter could also be highly correlated to BCM as it has been shown in smaller studies in lean minipigs. However, rapid pulsatile insulin secretion did not show a better correlation to BCM than combined stimulation with glucose and arginine, and thus analysis of pulses does not provide a better surrogate marker for BCM in the minipig. To evaluate the weaker correlation of glucose stimulation compared to combined glucose and arginine stimulation in vivo with BCM, we further investigated BCF in lean, beta-cell reduced minipigs by studying BCF in vitro after isolation and perfusion of their pancreases to investigate the ability of the remaining beta-cells to compensate for the loss of BCM by increasing insulin secretion per BCM. The perfused pancreas was chosen in order to allow direct measurement of the insulin secretion without the effects of peripheral tissues. During the perfusion, it was shown that the remaining beta-cells were indeed able to compensate for the loss of BCM to a large extent in response to stimulation with glucose and glucagon-like peptide-1 but not in response to arginine. This shows that the type of stimulus applied is important for the ability to compensate for reduced BCM from the remaining population of beta-cells, and further supports the use of combined stimulation with glucose and arginine for estimation of BCM in vivo. In conclusion, an animal model of reduced BCM and mild diabetes has been developed and characterized. The model has been used to evaluate effects of a primary reduction of BCM, showing a reduced rapid insulin pulse mass but normal periodicity and entrainability of the pulses, whereas obesity was associated with reduced rapid pulsatile insulin secretion. Thus, based on these data, the disturbed rapid pulsatile insulin secretion seen in T2DM humans may not directly be explained by the reduced BCM in diabetes, whereas obesity may be related to the reduced pulsatility. Furthermore, the model has been used to establish a correlation between extensive stimulation of insulin secretion in vivo and BCM obtained by stereology in both lean and obese animals. The ability to estimate BCM based on in vivo experiments in the minipig would allow longitudinal studies on changes in this parameter over time in the intact animal and support application of similar methods in humans. Such methods could be useful for the diagnosis and the measurement of the effectiveness of treatment of diabetes in humans in the future.
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PMID:Beta-cell function and mass in type 2 diabetes. 1972 71


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