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  • 1
    ISSN: 1432-0428
    Keywords: Keywords GLP-1 [7 ; 36 amide] ; incretin ; insulin ; glucagon ; pharmacokinetics.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intravenous glucagon-like peptide (GLP)-1 [7–36 amide] can normalize plasma glucose in non-insulin-dependent diabetic (NIDDM) patients. Since this is no form for routine therapeutic administration, effects of subcutaneous GLP-1 at a high dose (1.5 nmol/kg body weight) were examined. Three groups of 8, 9 and 7 patients (61 ± 7, 61 ± 9, 50 ± 11 years; BMI 29.5 ± 2.5, 26.1 ± 2.3, 28.0 ± 4.2 kg/m2; HbA1 c 11.3 ± 1.5, 9.9 ± 1.0, 10.6 ± 0.7 %) were examined: after a single subcutaneous injection of 1.5 nmol/kg GLP [7–36 amide]; after repeated subcutaneous injections (0 and 120 min) in fasting patients; after a single, subcutaneous injection 30 min before a liquid test meal (amino acids 8 %, and sucrose 50 g in 400 ml), all compared with a placebo. Glucose (glucose oxidase), insulin, C-peptide, GLP-1 and glucagon (specific immunoassays) were measured. Gastric emptying was assessed 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 〈 0.0001, respectively) and inhibited glucagon secretion (p 〈 0.0001). In fasting patients the repeated administration of GLP-1 normalized plasma glucose (5.8 ± 0.4 mmol/l after 240 min vs 8.2 ± 0.7 mmol/l after a single dose, p = 0.0065). With the meal, subcutaneous GLP-1 led to a complete cessation of gastric emptying for 30–45 min (p 〈 0.0001 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 infusion. Preparations with retarded release of GLP-1 would appear more suitable for therapeutic purposes because elevation of GLP-1 concentrations for 4 rather than 2 h (repeated doses) normalized fasting plasma glucose better. In the short term, there appears to be no tachyphylaxis, since insulin stimulation and glucagon suppression were similar upon repeated administrations of GLP-1 [7–36 amide]. It may be easier to influence fasting hyperglycaemia by GLP-1 than to reduce meal-related increments in glycaemia. [Diabetologia (1996) 39: 1546–1553]
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  • 2
    ISSN: 1432-0428
    Keywords: Key words GLP-1 [7 ; 36 amide] ; incretin ; insulin ; glucagon ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intravenous infusions of glucagon-like peptide 1 (GLP-1) [7–36 amide] are glucose-dependently insulinotropic and glucagonostatic and normalize plasma glucose concentrations in non-insulin-dependent diabetic patients. It was the aim of this study to investigate whether subcutaneous GLP-1 [7–36 amide] also has an influence on insulin and glucagon secretion, and which doses are required for significant effects. Therefore, eight healthy volunteers (24 ± 2 years, body mass index [BMI] 21.9 ± 2.3 kg/m2) were studied in the fasting state on five occasions in randomized order. Placebo (0.9 % NaCl with 1 % human serum albumin) or GLP-1 [7–36 amide] in doses of 0.15, 0.5, 1.5 or 4.5 nmol/kg body weight (volume 1 ml or, at the highest dose, 2 ml) was administered subcutaneously. An intravenous glucose bolus (0.33 g/kg body weight) was injected 30 min later. Blood was drawn for the measurement of glucose, insulin, C-peptide, GLP-1 [7–36 amide], and glucagon using specific radioimmunoassays. There were dose-related increments in GLP-1 [7–36 amide] concentrations (p 〈 0.0001). However, basal values were reached again after 90–120 min. Before glucose administration, insulin (p 〈 0.0001) and C-peptide (p 〈 0.0004) increased, whereas glucagon (p = 0.0018) and glucose (p 〈 0.0001) decreased in a dose-dependent manner. After glucose stimulation, integrated increments in insulin (p = 0.0007) and C-peptide (p = 0.02) were augmented and kG-values increased (p 〈 0.0001) in a dose-related fashion. The extent of reactive hypoglycaemia was related to the GLP-1 [7–36 amide] dose. With the highest GLP-1 [7–36 amide] dose, at the time of peak plasma concentrations, most volunteers felt unwell, and nausea and vomiting were observed in four subjects. In conclusion, subcutaneous GLP-1 [7–36 amide] is also able to stimulate insulin and inhibit glucagon secretion, thereby altering glucose assimilation. However, with unmodified GLP-1 [7–36 amide], the duration of action is short, and with high doses side effects are common. [Diabetologia (1995) 38: 720–725]
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Type 2 (non-insulin-dependent) diabetes mellitus ; incretin hormones ; glucagon-like peptide 1 (7-36 amide) ; pancreatic glucagon ; enteroinsular axis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glucagon-like peptide 1 (GLP-1) (7-36 amide) is a physiological incretin hormone that is released after nutrient intake from the lower gut and stimulates insulin secretion at elevated plasma glucose concentrations. Previous work has shown that even in Type 2 (non-insulin-dependent) diabetic patients GLP-1 (7-36 amide) retains much of its insulinotropic action. However, it is not known whether the magnitude of this response is sufficient to normalize plasma glucose in Type 2 diabetic patients with poor metabolic control. Therefore, in 10 Type 2 diabetic patients with unsatisfactory metabolic control (HbAlc 11.6±1.7%) on diet and sulphonylurea therapy (in some patients supplemented by metformin or acarbose), 1.2 pmol ×kg−1×min−1 GLP-1 (7-36 amide) or placebo was infused intravenously in the fasting state (plasma glucose 13.1±0.6 mmol/l). In all patients, insulin (by 17.4±4.7 nmol ×1−1×min; p=0.0157) and C-peptide (by 228.0±39.1 nmol×1−1×min; p=0.0019) increased significantly over basal levels, glucagon was reduced (by -1418±308 pmol ×1−1×min) and plasma glucose reached normal fasting concentrations (4.9±0.3 mmol/l) within 4 h of GLP-1 (7-36 amide) administration, but not with placebo. When normal fasting plasma glucose concentrations were reached insulin returned towards basal levels and plasma glucose concentrations remained stable despite the ongoing infusion of GLP-1 (7-36 amide). Therefore, exogenous GLP-1 (7-36 amide) is an effective means of normalizing fasting plasma glucose concentrations in poorly-controlled Type 2 diabetic patients. The glucose-dependence of insulinotropic actions of GLP-1 (7-36 amide) appears to be retained in such patients.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: GLP-1 [7–36 amide] ; incretin ; insulin ; glucagon ; pharmacokinetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intravenous infusions of glucagon-like peptide 1 (GLP-1) [7–36 amide] are glucose-dependently insulinotropic and glucagonostatic and normalize plasma glucose concentrations in non-insulin-dependent diabetic patients. It was the aim of this study to investigate whether subcutaneous GLP-1 [7–36 amide] also has an influence on insulin and glucagon secretion, and which doses are required for significant effects. Therefore, eight healthy volunteers (24±2 years, body mass index [BMI] 21.9±2.3 kg/ m2) were studied in the fasting state on five occasions in randomized order. Placebo (0.9% NaCl with 1% human serum albumin) or GLP-1 [7–36 amide] in doses of 0.15, 0.5, 1.5 or 4.5 nmol/kg body weight (volume 1 ml or, at the highest dose, 2 ml) was administered subcutaneously. An intravenous glucose bolus (0.33 g/kg body weight) was injected 30 min later. Blood was drawn for the measurement of glucose, insulin, C-peptide, GLP-1 [7–36 amide], and glucagon using specific radioimmunoassays. There were dose-related increments in GLP-1 [7–36 amide] concentrations (p〈0.0001). However, basal values were reached again after 90–120 min. Before glucose administration, insulin (p〈0.0001) and C-peptide (p〈0.0004) increased, whereas glucagon (p = 0.0018) and glucose (p〈0.0001) decreased in a dose-dependent manner. After glucose stimulation, integrated increments in insulin (p=0.0007) and C-peptide (p=0.02) were augmented and kG-values increased (p〈0.0001) in a dose-related fashion. The extent of reactive hypoglycaemia was related to the GLP-1 [7–36 amide] dose. With the highest GLP-1 [7–36 amide] dose, at the time of peak plasma concentrations, most volunteers felt unwell, and nausea and vomiting were observed in four subjects. In conclusion, subcutaneous GLP-1 [7–36 amide] is also able to stimulate insulin and inhibit glucagon secretion, thereby altering glucose assimilation. However, with unmodified GLP-1 [7–36 amide], the duration of action is short, and with high doses side effects are common.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Pancreas transplantation ; insulin secretion ; pancreatic hormones ; oral glucose tolerance ; glucagon stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After successful pancreas transplantation, insulin-dependent diabetic patients are characterized by a normal or at worst impaired oral glucose tolerance (World Health Organisation criteria). It is not known which pathophysiological mechanisms cause the difference between normal and impaired oral glucose tolerance. Therefore, we studied 41 patients after successful combined pancreas-kidney transplantation using stimulation in the fasting state with oral glucose (75 g), intravenous glucose (0.33 g/kg) and glucagon bolus injection (1 mg i.v.). Glucose (glucose oxidase), insulin and C-peptide (immunoassay) were measured. Repeated-measures analysis of variance and multiple regression analysis were used to analyse the results which showed: 28 patients had a normal, and 13 patients had an impaired oral glucose tolerance. Impaired oral glucose tolerance was associated with a greatly reduced early phase insulin secretory response (insulin p〈0.0001; C-peptide p=0.037). Age (p=0.65), body mass index (p=0.94), immunosuppressive therapy (cyclosporin A p=0.84; predniso(lo)ne p=0.91; azathioprine p=0.60) and additional clinical parameters were not different. Reduced insulin secretory responses in patients with impaired oral glucose tolerance were also found with intravenous glucose or glucagon stimulations. Exocrine secretion (α-amylase in 24-h urine collections) also demonstrated reduced pancreatic function in these patients (−46%; p=0.04). Multiple regression analysis showed a significant correlation of 120-min glucose with ischaemia time (p=0.003) and the number of HLA-DR mismatches (p=0.026), but not with HLA-AB-mismatches (p=0.084). In conclusion, the pathophysiological basis of impaired oral glucose tolerance after pancreas transplantation is a reduced insulin secretory capacity. Transplant damage is most likely caused by perioperative influences (ischaemia) and by the extent of rejection damage related, for example, to DR-mismatches.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Keywords Insulin secretion, protein kinase, insulin secreting cells, human CaMK II, cloning of new subtypes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. The Ca2+/calmodulin-dependent protein kinase II (CaMK II) is highly expressed in pancreatic islets and associated with insulin secretion vesicles. The suppression of CaMK II disturbs insulin secretion and insulin gene expression. There are four isoforms of CaMK II, α to δ, that are expressed from different genes in mammals. Our aim was to identify the isoforms of CaMK II expressed in human beta cells by molecular cloning from a human insulinoma cDNA library and to assess its distribution in humans.¶Methods. The previously unknown complete coding sequences of human CaMK II β and the kinase domain of CaMK II δ were cloned from a human insulinoma cDNA library. Quantitative determination of CaMK II isoform mRNA was carried out in several tissues and beta cells purified by fluorescence activated cell sorting and compared to the housekeeping enzyme pyruvate dehydrogenase.¶Results. We found CaMK IIβ occurred in three splice variants and was highly expressed in endocrine tissues such as adrenals, pituitary and beta cells. Liver showed moderate expression but adipose tissue or lymphocytes had very low levels of CaMK II β-mRNA. In human beta cells CaMK II β and δ were expressed equally with pyruvate dehydrogenase whereas tenfold lower expression of CaMK II γ and no expression of CaMK IIα were found.¶Conclusion/interpretation. Although CaMK II δ is ubiquitously expressed, CaMK II β shows preferential expression in neuroendocrine tissues. In comparison with the expression of a key regulatory enzyme in glucose oxidation, pyruvate dehydrogenase, two of the four CaM kinases investigated are expressed at equally high levels, which supports an important role in beta-cell physiology. These results provide the basis for exploring the pathophysiological relevance of CaMK IIβ in human diabetes. [Diabetologia (2000) 43: 465–473]
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  • 7
    ISSN: 1432-0428
    Keywords: Keywords Pancreas transplantation ; insulin secretion ; pancreatic hormones ; oral glucose tolerance ; glucagon stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After successful pancreas transplantation, insulin-dependent diabetic patients are characterized by a normal or at worst impaired oral glucose tolerance (World Health Organisation criteria). It is not known which pathophysiological mechanisms cause the difference between normal and impaired oral glucose tolerance. Therefore, we studied 41 patients after successful combined pancreas-kidney transplantation using stimulation in the fasting state with oral glucose (75 g), intravenous glucose (0.33 g/kg) and glucagon bolus injection (1 mg i. v.). Glucose (glucose oxidase), insulin and C-peptide (immunoassay) were measured. Repeated-measures analysis of variance and multiple regression analysis were used to analyse the results which showed: 28 patients had a normal, and 13 patients had an impaired oral glucose tolerance. Impaired oral glucose tolerance was associated with a greatly reduced early phase insulin secretory response (insulin p 〈 0.0001; C-peptide p = 0.037). Age (p = 0.65), body mass index (p = 0.94), immunosuppressive therapy (cyclosporin A p = 0.84; predniso(lo)ne p = 0.91; azathioprine p = 0.60) and additional clinical parameters were not different. Reduced insulin secretory responses in patients with impaired oral glucose tolerance were also found with intravenous glucose or glucagon stimulations. Exocrine secretion (α-amylase in 24-h urine collections) also demonstrated reduced pancreatic function in these patients (–46 %; p = 0.04). Multiple regression analysis showed a significant correlation of 120-min glucose with ischaemia time (p = 0.003) and the number of HLA-DR mismatches (p = 0.026), but not with HLA-AB-mismatches (p = 0.084). In conclusion, the pathophysiological basis of impaired oral glucose tolerance after pancreas transplantation is a reduced insulin secretory capacity. Transplant damage is most likely caused by perioperative influences (ischaemia) and by the extent of rejection damage related, for example, to DR-mismatches. [Diabetologia (1996) 39: 462–468]
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 40 (1997), S. 984-986 
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1440
    Keywords: Pancreas transplantation ; Insulin secretion ; Pancreatic hormones ; Gastrointestinal peptide hormones ; Rènal elimination (clearance) ; Systemic venous pancreas drainage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The secretion of pancreatic and gastrointestinal hormones in the basal state and after nutrient stimuli (50 g glucose, 50 g protein, or 30 g triglyceride administered on separate occasions) was assessed in ten previously type-1-diabetic patients after successful combined kidney and pancreas transplantation (systemic venous drainage). Fasting values were compared to matched non-diabetic kidney-transplanted patients and related to kidney function (endogenous creatinine clearance) and to the type and dosage of immunosuppressive medication. In the fasting state, only IR insulin concentrations were higher in pancreas-kidney-transplanted patients (by 88%; P=0.001) than in the kidney graft recipients. There were significant inverse correlations of plasma C-peptide, GIP, and gastrin immunoreactivity to endogenous creatinine clearance (kidney function). In response to nutrients, insulin secretion (IR insulin, C-peptide) was significantly stimulated by glucose, and — to a lesser degree — also by protein. Pancreatic glucagon was suppressed by glucose and stimulated by protein ingestion. GIP was raised after glucose and triglyceride more than after protein (P=0.0003). GLP-1 immunoreactivity was stimulated by all nutrients, with a tendency towards higher responses to protein and fat (P=0.06). Gastrin was mainly raised by protein. In conclusion, the overall pattern of pancreatic and gastrointestinal hormone release is normal in patients after combined pancreas-kidney-transplantation, but there are some peculiarities due to (a) systemic venous drainage of the pancreas graft (elevated fasting IR insulin) and (b) impaired kidney function (negative correlation of fasting plasma values to endogenous creatinine clearance for C-peptide, GIP, and gastrin). The plasma levels of these important regulatory peptides and their responses to nutrient stimulation are compatible with and may contribute to the well-preserved endocrine function of the pancreatic grafts (normal or slightly impaired glucose tolerance, preserved incretin effect).
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  • 10
    ISSN: 1432-5233
    Keywords: Key words Glucagon-like peptide 1 ; Leptin ; Obesity ; C-peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glucagon-like peptide 1 [7–36 amide] (GLP-1) and the obese gene product (leptin) are thought to be involved in the central regulation of feeding. Both may act from the peripheral circulation to influence brain function. To study potential interactions, GLP-1 ([7–36 amide]: 0.4, 0.8 pmol kg–1 min–1 or placebo on separate occasions) was infused intravenously (from –30 to 240 min) into nine healthy volunteers [age 26±3 years, body mass index: 22.9±1.6 kg/m2, glycated haemoglobin HbA1c: 5.0%± 0.2% (normal: 4.0%–6.2%), creatinine: 1.1±0.1 mg/dl], and (at 0 min) a liquid test meal (50 g sucrose in 400 ml 8% amino acid, total amino acids 80 g/l) was administered via a nasogastric tube. Plasma leptin (radioimmunoassay, RIA), glucose, insulin (microparticle enzyme immunoassay), C-peptide (enzyme-linked immunosorbent assay) and GLP-1 (RIA) were measured, and statistical analysis was done with repeated-measures ANOVA and Student's t-test. Plasma leptin concentrations were 31±6 pmol/l in the basal state. They did not change within 240 min after meal ingestion nor in response to the infusion of exogenous GLP-1 [7–36 amide] (P=0.99 for the interaction of experiment and time) leading to GLP-1 mean plasma levels of 25±2 and 36±3 (basal 6±1) pmol/l. On the other hand, glucose (from basal 4.7±0.1 to 6.0±0.2 mmol/l at 15 min, P〈0.05) and insulin (from basal 28±2 to 325±78 pmol/l at 45 min, P〈0.05) increased clearly after the meal with placebo. In conclusion, (1) plasma leptin levels in normal human subjects show no short-term changes after feeding a liquid mixed meal and (2) do not appear to be directly influenced by physiological and pharmacological elevations in plasma GLP-1 [7–36 amide] concentrations. This does not exclude interactions at the cerebral (hypothalamic) level or on more long-term temporal scales.
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