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B Gallwitz

Publications and source records attributed to B Gallwitz.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Influence of impaired glucose tolerance on long-term survival after acute myocardial infarction].

BACKGROUND AND OBJECTIVE: An impaired glucose tolerance as well as type 2 diabetes are associated with an increased cardiovascular mortality. This study was undertaken to determine whether this is also true for impaired glucose tolerance in immediate temporal relation with an acute myocardial infarction (AMI). PATIENTS AND METHODS: The survival of 562 patients (232 females, 330 males; age 68 +/- 13 years) consecutively admitted to the intensive care unit of a medical department with the diagnosis of AMI, were prospectively evaluated over a span of more than 3 years. Type 2 diabetes had been previously known in 152, while it was newly diagnosed in 83 patients. Oral glucose tolerance tests (OGTT) were performed in 129, but the test was not performed in 222 patients. Survival was analysed with the Kaplan-Meier test. RESULTS: Among the 129 patients who had had an OGTT, it was normal in 60 (47%), 45 (35%) had impaired glucose tolerance and 24 (19%) were found to have previously undiagnosed diabetes (WHO criteria). Survival of all patients with type 2-diabetes was significantly worse than in the remainder of patients (p < 0.0001). In patients with impaired glucose tolerance the survival time was significantly shorter than in those with normal glucose tolerance (p = 0.029). Even after excluding those patients who had died in the acute post-infarction phase, the difference between patients with normal and with impaired glucose tolerance remained significant (p = 0.034). CONCLUSION: Patients with impaired glucose tolerance have a significantly shorter survival after AMI than those with a normal glucose tolerance. Blood glucose concentration 2 hours after oral glucose intake thus seems to be an important predictor of death after AMI.

Aged↗
PubMed2000

GLP-1-analogues resistant to degradation by dipeptidyl-peptidase IV in vitro.

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion and improves glycemic control in type 2 diabetes. In serum the peptide is degraded by dipeptidyl peptidase IV (DPP IV). The resulting short biological half-time limits the therapeutic use of GLP-1. DPP IV requires an intact alpha-amino-group of the N-terminal histidine of GLP-1 in order to perform its enzymatic activity. Therefore, the following GLP- analogues with alterations in the N-terminal position 1 were synthesized: N-methylated- (N-me-GLP-1), alpha-methylated (alpha-me-GLP-1), desamidated- (desamino-GLP-1) and imidazole-lactic-acid substituted GLP-1 (imi-GLP-1). All GLP-1 analogues except alpha-me-GLP-1 were hardly degraded by DPP IV in vitro. The GLP-1 analogues showed receptor affinity and in vitro biological activity comparable to native GLP-1 in RINm5F cells. GLP-1 receptor affinity was highest for imi-GLP-1, followed by alpha-me-GLP-1 and N-me-GLP-1. Only desamino-GLP-1 showed a 15-fold loss of receptor affinity compared to native GLP-1. All analogues stimulated intracellular cAMP production in RINm5F cells in concentrations comparable to GLP-1. N-terminal modifications might therefore be useful in the development of long-acting GLP-1 analogues for type 2 diabetes therapy.

Animals↗
PubMed2000

Insulin secretion defects in liver cirrhosis can be reversed by glucagon-like peptide-1.

Liver cirrhosis is often accompanied by a disturbed carbohydrate metabolism similar to type 2 diabetes. To investigate the severity of the defect in insulin secretion in this form of diabetes, we measured insulin release from isolated pancreatic islets of rats with CCl(4)-phenobarbital-induced liver cirrhosis. Cirrhosis was confirmed by clinical signs, elevated liver enzymes and histology. Fasting venous plasma glucose concentrations were equal in rats with liver cirrhosis and in controls. Plasma insulin and glucagon concentrations were significantly greater (P<0.01) in cirrhotic rats than in control animals. Glucose (16.7 mM)-induced stimulation of insulin release from pancreatic islets revealed a twofold increase in control and cirrhotic rats. Basal and stimulated insulin secretion, however, were significantly lower in cirrhotic animals. The incretin hormone, glucagon-like peptide-1 (GLP-1), has therapeutic potential for the treatment of type 2 diabetes. Therefore, islets from control and cirrhotic animals were incubated with GLP-1 in concentrations from 10(-)(11) to 10(-)(6) M. GLP-1 stimulated insulin release in a concentration-dependent manner. In islets from cirrhotic rats, basal and stimulated insulin secretion was blunted compared with controls. These data show that the hyperinsulinemia observed in liver cirrhosis is not due to an increase of insulin secretion from islets, but could be explained by decreased hepatic clearance of insulin. GLP-1 may ameliorate diabetes in patients with liver cirrhosis.

Analysis of Variance↗
PubMed1999

Biological activity of GLP-1-analogues with N-terminal modifications.

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion and improves glycemic control in type 2 diabetes. In serum the peptide is degraded by dipeptidyl peptidase IV (DPP IV). The resulting short biological half-time limits the therapeutic use of GLP-1. Therefore, various GLP-1 analogues with alterations in cleavage positions were synthesized. GLP-1-receptor binding was investigated in RINm5F cells. Biological activity of the GLP-1 analogues was investigated in vitro by measuring cAMP production in RINm5F cells. GLP-1 analogues with modifications in position 2 were not cleaved by DPP IV and showed receptor affinity and in vitro biological activity comparable to native GLP-1. Analogues with alterations in positions 2 and 8, 2 and 9 or 8 and 9 showed a significant decrease in receptor affinity and biological activity. In vivo biological activity was tested in pigs. GLP-1 analogues were administered subcutaneously followed by an intravenous bolus injection of glucose. Plasma glucose and insulin were monitored over 4 h. Compared to native GLP-1, analogues with an altered position 2 showed similar or increased potency and biological half-time. Other GLP-1 analogues were less active. Despite the lack of degradation of these GLP-1 analogues by DPP IV in vitro, their biological action is as short as that of GLP-1, except for desamino-GLP-1, indicating that other degradation enzymes are important in vivo. Alterations of GLP-1 in positions 8 or 9 result in a loss of biological activity without extending biological half-time.

Cyclic AMP↗
PubMed1999

Comparison of the effect of native glucagon-like peptide 1 and dipeptidyl peptidase IV-resistant analogues on insulin release from rat pancreatic islets.

BACKGROUND: Glucagon-like peptide 1 (GLP-1) stimulates insulin secretion and may improve glycaemic control in type 2 diabetes. Therapeutic use is limited by its rapid degradation, primarily by dipeptidyl peptidase IV. MATERIALS AND METHODS: Five GLP-1 analogues with alterations at cleavage positions were synthesized according to the Fmoc strategy and tested for metabolic stability by incubation with rat kidney membranes containing dipeptidyl peptidase IV activity. Their insulinotropic effect was compared in isolated rat pancreatic islets after 24 h maintenance in tissue culture. Ten islets per vial were incubated for 30 min; insulin was measured radioimmunologically. Each analogue was compared with GLP-1 in the same experiment. RESULTS: All analogues were biologically active in isolated islets in the potency order da2d8 = da2 > d2d9 > da2ds8 > desamino. At 16.7 mmol L-1 glucose, GLP-1 and GLP-1 analogues altered as position 2, or 2 and 8 significantly (P < 0.05) increased insulin release at 10(-9) mol L-1. N-terminal modification of GLP-1 confers resistance to dipeptidyl peptidase IV degradation in rat kidney membranes in vitro. CONCLUSIONS: The analogues tested are biologically active and resistant to degradation by dipeptidyl peptidase IV. Their greater metabolic stability may help to realize the potential of GLP-1 analogues in diabetes therapy.

Amino Acid Sequence↗
PubMed1998

Effect of human pancreastatin peptide (hP-16) on oral glucose tolerance in man.

The gastrointestinal peptide, pancreastatin, has been shown to inhibit insulin release and exocrine pancreatic secretion in the rat. Human pancreastatin-like peptides first isolated from a carcinoid tumor, are expressed in human islets of Langerhans. To investigate the influence of human pancreastatin-16 (hP-16) on oral glucose tolerance (OGTT) in non-diabetic humans, we synthesized the C-terminally amidated human pancreastatin peptide. Healthy male volunteers (n = 6) received in a double-blind placebo-controlled study a 75 g standard OGTT during the i.v. infusion of hP-16 (10 pmol/kg/min) or saline over a time period of 3 h. Peak glucose levels (mg/dl) declined from 151.4 +/- 10.3 (control) to 122.5 +/- 9.7 (hP-16) (mean +/- SEM), peak insulin levels (microU/ml) from 46.3 +/- 2.9 (hP-16) to 32.2 +/- 4.0 (control) and peak C-peptide levels (pmol/ml) from 1.9 +/- 0.1 (hP-16) to 1.2 +/- 0.1 (control). Integrated incremental glucose, insulin and C-peptide responses were reduced by 47% (p < 0.001), 23% (p < 0.05) and 15% (p < 0.05), respectively. In conclusion, these findings indicate that hP-16 attenuates the elevation of blood glucose and insulin levels after an oral glucose load in non-diabetic humans.

Adult↗
PubMed1997

Thyroid autoantibodies and thyroid dysfunction during treatment with interferon-alpha for chronic hepatitis C.

Interferon-alpha (2a or 2b) is increasingly used for treatment of chronic hepatitis C virus (HCV) infection. Recent reports suggested a correlation between increases in thyroid autoantibodies and the development of thyroid dysfunction during interferon-alpha therapy. In this study, we analyzed thyroid hormones and antithyroid antibodies at monthly intervals in 53 patients who received interferon alpha for chronic active hepatitis C infection. Of five patients with initially elevated levels of antithyroid peroxydase antibodies (anti-TPO), the antibodies increased further in two of them. Ten patients, who started interferon therapy with normal antibody levels, developed elevated anti-TPO antibodies for limited times during treatment. Levels of anti-TPO antibodies showed a marked fluctuation, and only three patients had increased anti-TPO antibodies persisting for longer than 3 mo. Antithyroglobulin antibodies appeared in four patients, all of whom were also positive for anti-TPO antibodies. No changes in TRAB levels were observed. All of these patients with elevated antithyroid antibodies remained in an euthyroid state. One patient with normal antithyroid antibodies developed thyroiditis with severe thyrotoxicosis after 9 wk of interferon therapy. These findings suggest that the induction of antithyroid antibodies during treatment with interferon-alpha does not indicate clinical relevant thyroid dysfunction. Routine measurement of antithyroid antibodies during interferon-alpha therapy does not seem to be mandatory.

Adult↗
PubMed1996

GLP-1/GIP chimeric peptides define the structural requirements for specific ligand-receptor interaction of GLP-1.

The gastrointestinal hormones glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) strongly stimulate insulin release. Despite their high N-terminal sequence similarity, GLP-1 does not bind to the GIP receptor and vice versa. To characterize the domains required for interaction of the peptide ligands with their specific receptors, we performed displacement studies with various synthetic GLP-1/GIP hybrid peptides on RINm5F insulinoma cells. Displacement of 125I-GIP and 125I-GLP-1 was measured using GLP-1/GIP chimeras which comprised GIP and GLP-1 sequences at different positions. The binding affinity to the GLP-1 receptor was found to be sensitive to GIP-like exchanges in the N-terminal 22 amino acids as well as in positions 13 and 15 (loss of affinity 280-fold to more than 1000-fold). C-terminal substitution of the GLP-1 sequence by GIP diminished the affinity towards the GLP-1 receptor only 20-fold. All hybrid peptides investigated showed minimal binding affinity for the GIP receptor, indicating that the entire GIP-sequence (1-31) is important for receptor recognition. These findings provide insight into the structural requirements for the specific interaction of two important insulinotropic peptides with their specific receptors.

Amino Acid Sequence↗
PubMed1994

Structure/activity characterization of glucagon-like peptide-1.

Glucagon-like peptide-1 is a gastrointestinal hormone that strongly stimulates insulin release via specific receptors on the pancreatic beta-cell. To characterize the side-chain groups required for interaction of glucagon-like peptide-1 with its receptor, we performed binding studies with alanine-substituted glucagon-like peptide-1 analogues on RINm5F insulinoma cells. The binding affinity and biological activity of glucagon-like peptide-1 have been found to be sensitive to alanine exchanges in the N-terminal positions 1, 4, 6 and the C-terminal positions 22 and 23. Alanine substitutions at positions 5, 8, 10-12, 14, 16-21 and 25-30 do not change receptor affinity. These findings could be exploited to design glucagon-like peptide-1 agonists and probably antagonists for further physiological studies.

Amino Acid Sequence↗