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  • 5-methoxyindoles  (6)
  • insulin secretion  (5)
  • growth hormone  (4)
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  • 1
    ISSN: 1432-0428
    Keywords: Phenformin ; sulphonylureas ; blood glucose ; lactate ; pyruvate ; ketone bodies ; alanine ; glycerol ; non-esterified fatty acids ; growth hormone ; gluconeogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve hour metabolic rhythms have been determined in two groups of subjects during combined therapy with a sulphonylurea and phenformin 50 mg twice daily. Subjects with clinical evidence of complications of diabetes showed greater abnormalities in concentrations of blood intermediary metabolites than a group of subjects without complications despite similar mean blood glucose concentrations in the two groups (7.6 mmol/l with complications; 7.3 mmol/l without complications). Mean blood lactate (1.93 mmol/l v 1.39 mmol/l), alanine (0.56 mmol/1 v 0.43 mmol/l), total blood ketone bodies (0.20 mmol/l v 0.14 mmol/l) and several other intermediary metabolites and their ratios were significantly higher in the group with diabetic complications. It is suggested that the differences between the two groups may arise from impaired disposal of phenformin leading to higher blood concentrations in the group with diabetic complications, despite normal liver function tests and plasma creatinine concentration. It is probable that this accumulation of phenformin results in more pronounced effect upon blood glucose and other intermediary metabolites. Thus, the metabolic abnormalities previously reported in patients treated by phenformin alone are also present during combined sulphonylurea and phenformin therapy, and in the presence of diabetic microangiopathy these abnormalities are accentuated.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Metabolic control ; artificial pancreas ; lactate ; pyruvate ; glycerol ; non-esterified fatty acids ; total ketone bodies ; glucose turnover ; glucose recycling ; glucagon ; growth hormone ; Type 1 diabetes ; subcutaneous insulin therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve insulin deficient Type 1 (insulin-dependent) diabetic subjects were studied over an 11 1/2 h period during both subcutaneous insulin therapy and closed loop insulin delivery, using a glucose controlled insulin infusion system (Biostator) programmed to maintain normoglycaemia. Results were compared with those from 21 age and weight-matched normal subjects. Using the Biostator, normoglycaemia was achieved in all diabetic subjects within 3.5 h and normal profiles maintained thereafter. Blood metabolite and hormone values were evaluated during the subsequent 8 h normoglycaemic period. Subcutaneous therapy resulted in abnormal glucose levels throughout the study period (mean 8 h value 8.3±0.7 compared with 5.6±0.3 mmol/l on feedback control and 5.5.±0.1 mmol/l in normal subjects). The mean value of lactate and pyruvate over the final 8 h period was 25% higher in diabetic patients than in normal subjects with no difference between the two insulin treatments (blood lactate: 0.94±0.04 on subcutaneous insulin, 0.91±0.04 on feedback control and 0.74±0.03 mmol/l in control subjects). The pre-prandial peaks of blood glycerol and plasma non-esterified fatty acids were significantly decreased or absent during both feedback control and subcutaneous therapy in comparison with the normal subjects, whereas after the midday and evening meals, total ketone body levels were significantly higher in the diabetic patients. Peripheral serum free insulin levels were two-to fourfold greater in the diabetic than in the normal subjects. There were no significant differences between levels in diabetic patients receiving subcutaneous insulin or on the Biostator. Glucose turnover (1600–1800 h) was normal on feedback control (1.41±0.20 versus 1.55±0.18 mg · kg-1 · min-1 in the normal subjects) but was significantly decreased during subcutaneous insulin (1.04±0.09 mg · kg-1 · min-1). There was, in addition, a decrease in glucose recycling during both subcutaneous insulin therapy and feedback control in the diabetic subjects. These data suggest that although fine control of glucose metabolism both in terms of circulating concentrations and rates of production can be achieved by feedback-control, insulin infusion by the peripheral route is associated with significant metabolic abnormalities, at least in the short term. Longer term studies and examination of portal insulin delivery seem warranted.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Key words Impaired glucose tolerance ; insulin sensitivity ; hepatic glucose output ; insulin secretion ; labelled infusion technique.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent evidence suggests that the postprandial hyperglycaemia in impaired glucose tolerance is primarily due to impaired suppression of basal hepatic glucose output. This in turn appears to be secondary to decreased first phase insulin secretion, although decreased hepatic insulin sensitivity, which is a feature of non-insulin-dependent diabetes mellitus, might also play a role. Eight mildly overweight subjects with impaired glucose tolerance and eight closely matched control subjects with normal glucose tolerance underwent an intravenous glucose tolerance test to assess first phase insulin secretion. Insulin sensitivity was examined by a 150-min hyperinsulinaemic-euglycaemic clamp. Somatostatin was infused from 150 min to suppress endogenous insulin secretion, and glucagon and insulin were replaced by constant infusion. Glucose with added dideuterated glucose (labelled infusion technique) was infused to maintain euglycaemia. First phase insulin secretion (Δ 0–10 min insulin area 7 Δ 0–10 min glucose area) was significantly decreased in the subjects with impaired glucose tolerance (median [range]: 1.2 [0.2–19.4] vs 9.1 [2.6–14.5] mU · mmol−1; p 〈 0.01). During the clamp, circulating insulin (93 ± 8 [mean ± SEM] and 81 ± 10 mU · l−1) and glucagon (54 ± 4 and 44 ± 6 ng · l−1) levels were comparable. Total glucose disposal was decreased in subjects with impaired glucose tolerance (2.78 ± 0.27 vs 4.47 ± 0.53 mg · kg−1· min−1; p 〈 0.02), and was primarily due to decreased non-oxidative glucose disposal. However, hepatic glucose output rates were comparable during the clamp (0.38 ± 0.10 and 0.30 ± 0.18 mg · kg−1· min−1). Therefore, the main defects in subjects with impaired glucose tolerance are decreased first phase insulin secretion and peripheral non-oxidative glucose disposal, but hepatic glucose output shows normal responsiveness to insulin. [Diabetologia (1995) 38: 699–704]
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Keywords C-peptide ; proinsulin ; insulin ; insulin secretion ; insulin resistance ; insulin clearance ; families ; adiposity ; glucose intolerance.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-diabetic first degree relatives of non-insulin-dependent diabetic (NIDDM) families are at increased risk of developing diabetes mellitus, and have been studied to identify early metabolic abnormalities. Hormone concentrations measured by specific enzyme immunoassays were assessed in non-diabetic relatives of North European extraction, and control subjects with no family history of diabetes were matched for age, sex and ethnicity. A 75-g oral glucose tolerance test was conducted and those with newly diagnosed NIDDM were excluded. Basal insulin resistance was determined by homeostasis model assessment (HOMA), and hepatic insulin clearance by C-peptide:insulin molar ratio. Relatives (n = 150) were heavier (BMI: p 〈 0.0001) than the control subjects (n = 152), and had an increased prevalence of impaired glucose tolerance (15 vs 3 %, p 〈 0.01). The relatives had increased fasting proinsulin levels and decreased C-peptide levels following the glucose load, while insulin levels were increased at all time points. To examine whether the differences in hormone levels were secondary to the differences in glucose tolerance and adiposity, we studied 100 normal glucose tolerant relatives and control subjects pair-matched for age, sex, waist-hip ratio and BMI. The differences in proinsulin levels were no longer apparent. However, the relatives remained more insulin resistant, and had decreased C-peptide levels and C-peptide:insulin ratios at all time points. In conclusion, we have identified several metabolic abnormalities in the normal glucose tolerant relatives, and propose that the decreased hepatic insulin clearance helps to maintain normoglycaemia in the face of combined insulin resistance and decreased insulin secretion. [Diabetologie (1997) 40: 1185–1190]
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Phenformin ; metformin ; glibenclamide ; blood glucose ; lactate ; alanine ; pyruvate ; ketone bodies ; maturity-onset diabetes ; diabetic control ; gluconeogenesis ; glycerol ; insulin ; triglycerides ; growth hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve hour metabolic rhythms have been performed on six maturity-onset diabetic subjects during successive periods of therapy with phenformin, metformin, and glibenclamide. Moderate control of blood glucose concentration was achieved with phenformin and metformin, the lowest concentrations being found with glibenclamide. Mean blood lactate concentration was grossly elevated during phenformin therapy, moderately elevated with metformin and normal during glibenclamide treatment. Similar patterns were found for the lactate/pyruvate ratio, alanine, glycerol and ketone bodies. Serum triglyceride concentrations were significantly higher during phenformin treatment than with the other two regimes. Serum insulin concentration was higher on glibenclamide than with either biguanide. Most of these effects of the biguanides could be accounted for by an inhibitory effect on hepatic gluconeogenesis. It is concluded that the use of biguanides as hypoglycaemic agents in diabetes is associated with the production of multiple metabolic abnormalities.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: C-peptide ; insulin secretion ; C-peptide pharmacokinetics ; insulin dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An understanding of the metabolic abnormalities rising from inappropriate insulin delivery in diabetic patients demands a knowledge of 24-h and basal insulin secretion rates in normal man. We have used biosynthetic human C-peptide to determine its kinetic parameters in 10 normal subjects and applied these to measurements of plasma concentrations in the same subjects to determine pancreatic secretion rate. Metabolic clearance rate measured by stepped primed infusion of biosynthetic human C-peptide at rates of 10, 19 and 26nmol/h was 4.7±0.7 (±SD) ml·kg−1·min−1, and was independent of infusion rate. Fractional clearance (T1/2, 26±3 min) and distribution volume (0.178±0.039 l/kg) were calculated from the decline in concentration after cessation of the highest rate infusion. Basal insulin secretion calculated from the C-peptide metabolic clearance rate and plasma concentrations for the period 02.00 to 07.00 hours was 1.3±0.4U/h. Over 24h total insulin secretion on a standard high carbohydrate diet was 63±15 U, calculated from the area under the C-peptide concentration curve. Basal insulin secretion, therefore, accounted for 50±8% of total insulin secretion. Although only 5.6±1.1% of C-peptide was detected in 24-h urine collections, urinary C-peptide excretion was significantly related to 24-h C-peptide secretion (r=0.74,p〈0.02).
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Impaired glucose tolerance ; insulin sensitivity ; hepatic glucose output ; insulin secretion ; labelled infusion technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent evidence suggests that the post-prandial hyperglycaemia in impaired glucose tolerance is primarily due to impaired suppression of basal hepatic glucose output. This in turn appears to be secondary to decreased first phase insulin secretion, although decreased hepatic insulin sensitivity, which is a feature of non-insulin-dependent diabetes mellitus, might also play a role. Eight mildly overweight subjects with impaired glucose tolerance and eight closely matched control subjects with normal glucose tolerance underwent an intravenous glucose tolerance test to assess first phase insulin secretion. Insulin sensitivity was examined by a 150-min hyperinsulinaemic-euglycaemic clamp. Somatostatin was infused from 150 min to suppress endogenous insulin secretion, and glucagon and insulin were replaced by constant infusion. Glucose with added dideuterated glucose (labelled infusion technique) was infused to maintain euglycaemia. First phase insulin secretion (Δ 0–10 min insulin area ÷Δ 0–10 min glucose area) was significantly decreased in the subjects with impaired glucose tolerance (median [range]: 1.2 [0.2–19.4] vs 9.1 [2.6–14.5] mU·mmol−1; p〈0.01). During the clamp, circulating insulin (93±8 [mean±SEM] and 81±10 mU·l−1) and glucagon (54±4 and 44±6 ng·l−1) levels were comparable. Total glucose disposal was decreased in subjects with impaired glucose tolerance (2.78±0.27 vs 4.47±0.53 mg·kg−1·min−1; p〈0.02), and was primarily due to decreased non-oxidative glucose disposal. However, hepatic glucose output rates were comparable during the clamp (0.38±0.10 and 0.30±0.18 mg·kg−1·min−1). Therefore, the main defects in subjects with impaired glucose tolerance are decreased first phase insulin secretion and peripheral non-oxidative glucose disposal, but hepatic glucose output shows normal responsiveness to insulin.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Keywords: Keywords Prediabetes ; physiological approach ; 24-h profile ; glucose ; insulin ; insulin secretion ; proinsulin ; non-esterified fatty acids ; gut incretin hormones ; intermediary metabolites.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. Insulin resistance is a common feature in relatives of patients with Type II (non-insulin-dependent) diabetes mellitus and abnormalities in beta-cell function can also exist. Insight into non-fasting carbohydrate metabolism in these potentially prediabetic subjects relies almost exclusively on studies in which glucose is infused or ingested or both. We aimed to characterize insulin secretion and aspects of hormonal and metabolic patterns in relatives using a physiological approach. Methods. We examined profiles of insulin, C peptide, proinsulin, gut incretin hormones and fuel substrates in 26 glucose tolerant but insulin resistant (clamp) relatives and 17 control subjects during a 24-hour period including three meals. Results. During the day plasma glucose was slightly raised in relatives (p 〈 0.05). Overall insulin secretion calculated on the basis of C peptide kinetics were increased in relatives (p 〈 0.0005) whereas incremental insulin secretion after all three meals were similar. Peak incremental insulin secretion tended, however, to be reduced in relatives (p 〈 0.10). Despite considerably increased insulin concentrations in relatives (70 %, p 〈 0.001), serum NEFA did not differ. Postprandial proinsulin concentrations (p 〈 0.05), but not proinsulin:insulin ratios, were increased in relatives. After meals concentrations of glucose-dependent-insulinotropic polypeptide (p 〈 0.05) were increased in relatives. Glucagon-like peptide-1 concentrations were similar. Conclusion/interpretation. Several hormonal and metabolic aberrations are present in healthy relatives of Type II diabetic patients during conditions that simulate daily living. Increased concentrations of glucose-dependent-insulinotropic polypeptide could indicate a beta-cell receptor defect for glucose-dependent-insulinotropic polypeptide in the prediabetic stage of Type II diabetes. Incremental insulin secretion after mixed meals appear normal in relatives, although a trend towards diminished peak values possibly signifies early beta-cell dysfunction. [Diabetologia (1999) 42: 1314–1323]
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 23-28 
    ISSN: 1432-1041
    Keywords: dopamine ; somatostatin ; insulin ; glucagon ; growth hormone ; plasma glucose ; NEFA ; lipolysis ; ketogenesis ; insulin-deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The metabolic effects of dopamine have been investigated by its infusion in normal man with and without simultaneous somatostatin administration. Dopamine was infused into overnight fasted men at 1.5 µg/kg/min (n=6) and 3.0 µg/kg/min (n=5) for 120 min. Plasma dopamine concentrations at 120 min were 78±9 nmol/l and 117±17 nmol/l respectively, associated with a marginal rise in plasma noradrenaline. Dopamine (1.5 µg/kg/min) induced an early and sustained rise in plasma glucagon (48±9 pg/ml versus 19±6 pg/ml in saline controls at 10 min, p〈0.01)and a transient elevation in serum growth hormone which peaked to 17.7 (range 4.5–71.8)mU/l at 60 min (7.2 (range 0.6–37.7) mU/l with saline, p〈0.05), but did not alter serum insulin, blood glucose or other metabolite levels. At 3.0 µg/kg/min, dopamine in addition provoked mild and transient elevations in blood glucose and serum insulin. Somatostatin (250 µg/h) suppressed circulating insulin, glucagon, and growth hormone levels and abolished the small hyperglycaemic effect seen with the higher dopamine dose. Somatostatin alone induced a progressive rise in circulating non-esterified fatty acid and 3-hydroxybutyrate levels reflecting insulin deficiency. This rise in NEFA and 3-hydroxybutyrate was increased by dopamine particularly at the higher dosage (plasma NEFA; somatostatin alone, 1.08±0.13 mmol/l; somatostatin plus dopamine 3 µg/kg/min, 1.44±0.17 mmol/l at 120 min, p〈0.01: blood 3-hydroxybutyrate; somatostatin alone, 0.32±0.04 mmol/l; somatostatin plus dopamine 3 µg/kg/min, 0.56±0.12 mmol/l at 120 min, p〈0.05). Thus: 1) dopamine at pharmacological dosage has minor effects when other endocrine mechanisms are intact, 2) it enhances lipolysis and ketogenesis during somatostatin-induced insulin deficiency, 3) the hyperglycaemic effect of the higher dopamine dose is probably mediated through stimulated glucagon secretion.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1435-1463
    Keywords: Pineal ; melatonin/5-methoxytryptophol ; 5-methoxyindoles ; pteridines ; red light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In previous investigations the change of circadian rhythmicity in pineal melatonin/5-methoxytryptophol synthesis of rats periodically exposed to red light was similar to that in pineals of rats incubated with pterin-6-aldehyde. These experiments were, however, performed with rats of different age and in different periods of the year. In the present study these two factors influencing pineal indole metabolism have been combined the experiments being carried out in rats aged 28 days and during the same day in the month of January. It was observed that under influence of red light the peak of melatonin/5-methoxytryptophol synthesis shifted towards daytime, whereas incubation with pterin-6-aldehyde did not cause such a shift. If under different experimental conditions the mean amount of melatonin/5-methoxytryptophol which was formed over a 24 hour period was compared, it appeared that pineals of rats exposed to white light incubated with reduced neopterin but not pineals incubated with pterin-6-aldehyde behave in this respect similar to pineals of rats exposed to red light. However, if the ratio between melatonin/5-methoxytryptophol and 5-methoxytryptamine is calculated pineals of white light exposed rats incubated in pterin-6-aldehyde behaved very similar to the pineals of rats exposed to red light. Although the role of pteridines remains obscure, it appears that the parameters 1. circadian rhythmicity and 2. the amount of 5-methoxyindoles and 3. the ratio between these indole derivatives might be of importance in analyzing their physiological effects. The influence of application of light of different wavelenghts and year rhythmicity is discussed.
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