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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 16 (1979), S. 261-266 
    ISSN: 1432-0428
    Keywords: Perfused pancreas ; somatostatin ; insulin ; glucagon ; calcium ; acetylcholine ; glucose ; isoproterenol ; arginine ; radioimmunoassay ; dog pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of calcium on somatostatin secretion was investigated in the isolated, perfused canine pancreas preparation and compared with those of acetylcholine, glucose, isoproterenol and arginine. Calcium (5 mmol/l) stimulated somatostatin release in a typical biphasic response pattern being about 5 times as potent as acetylcholine (1 μmol/l), arginine (5 mmol/l), and isoproterenol (2 ng/ml) while the release of insulin and glucagon in response to calcium and the other secretagogues were of the same magnitude. Somatostatin release increased progressively when perfusate calcium was increased step-wise from 0 through 1.25 and 2.5 to 5.0 mmol/l. Calcium stimulated the secretion of somatostatin in the absence of glucose. The stimulatory effect of calcium was, however, modulated by the glucose concentration being about twice as large at 200 mg/100 ml as at 25 mg/100 ml glucose in the perfusion medium.
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  • 2
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; microalbuminuria ; blood pressure ; monounsaturated fat diet ; olive oil ; diet ; metabolic control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous studies have shown that unsaturated fat-enriched diets may have a beneficial effect on blood pressure in non-insulin-dependent diabetic (NIDDM) patients, whereas little is known about the effects on albuminuria. In a 3-week cross-over design we compared the effects of a currently recommended high-carbohydrate diet (50% carbohydrate, 30% fat [10% monounsaturated fat]) vs a diet rich in monounsaturated fat (30% carbohydrate, 50% fat [30% monounsaturated fat]) on urinary albumin excretion rate, 24-h ambulatory blood pressure and metabolic control in ten NIDDM patients with persistent microalbuminuria. The 24-h ambulatory blood pressure was similar before and after both the high-carbohydrate diet (mean±SD: 145/78±25/10 vs 143/79±19/10 mmHg (NS) and the monounsaturated fat diet: 140/78±16/8 vs 143/79±15/8 mmHg (NS). No changes were observed in day or night-time blood pressures. Urinary albumin excretion rate was unaffected after 3 weeks' treatment by the diets: from (geometric mean ×/÷ tolerance factor) 32.4×/÷2.1 to 36.0×/÷1.9 Μg/min (NS) vs from 34.2×/÷1.9 to 32.1×/÷2.1 Μg/min (NS). Fasting plasma glucose, serum fructosamine and HbA1c as well as lipid and lipoprotein concentrations were stable during both diets. Compared to the high-carbohydrate diet a reduction in the LDL/HDL cholesterol ratio was observed during the monounsaturated fat diet (p〈0.03). In conclusion, compared to a high-carbohydrate diet, 3 weeks' treatment with a monounsaturated fat diet did not affect the levels of 24-h ambulatory blood pressure or albuminuria in microalbuminuric NIDDM patients. Moreover, glycaemic control and lipoprotein levels were unchanged, although a potential beneficial effect on the LDL/HDL-cholesterol ratio was noted. Monounsaturated fat represents an alternative in the diets of NIDDM patients especially when caloric intake is not a concern.
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  • 3
    ISSN: 1432-0428
    Keywords: Key words Non-insulin-dependent diabetes mellitus; microalbuminuria ; blood pressure ; monounsaturated fat diet ; olive oil ; diet ; metabolic control.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous studies have shown that unsaturated fat-enriched diets may have a beneficial effect on blood pressure in non-insulin-dependent diabetic (NIDDM) patients, whereas little is known about the effects on albuminuria. In a 3-week cross-over design we compared the effects of a currently recommended high-carbohydrate diet (50 % carbohydrate, 30 % fat [10 % monounsaturated fat]) vs a diet rich in monounsaturated fat (30 % carbohydrate, 50 % fat [30 % monounsaturated fat]) on urinary albumin excretion rate, 24-h ambulatory blood pressure and metabolic control in ten NIDDM patients with persistent microalbuminuria. The 24-h ambulatory blood pressure was similar before and after both the high-carbohydrate diet (mean ± SD: 145/78 ± 25/10 vs 143/79 ± 19/10 mmHg (NS) and the monounsaturated fat diet: 140/78 ± 16/8 vs 143/79 ± 15/8 mmHg (NS). No changes were observed in day or night-time blood pressures. Urinary albumin excretion rate was unaffected after 3 weeks' treatment by the diets: from (geometric mean ×/7 tolerance factor) 32.4 ×/72.1 to 36.0 ×/7 1.9 μg/min (NS) vs from 34.2 ×/7 1.9 to 32.1 ×/7 2.1 μg/min (NS). Fasting plasma glucose, serum fructosamine and HbA1c as well as lipid and lipoprotein concentrations were stable during both diets. Compared to the high-carbohydrate diet a reduction in the LDL/HDL cholesterol ratio was observed during the monounsaturated fat diet (p 〈 0.03). In conclusion, compared to a high-carbohydrate diet, 3 weeks' treatment with a monounsaturated fat diet did not affect the levels of 24-h ambulatory blood pressure or albuminuria in microalbuminuric NIDDM patients. Moreover, glycaemic control and lipoprotein levels were unchanged, although a potential beneficial effect on the LDL/HDL-cholesterol ratio was noted. Monounsaturated fat represents an alternative in the diets of NIDDM patients especially when caloric intake is not a concern. [Diabetologia (1995) 38: 1069–1075]
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  • 4
    ISSN: 1432-0428
    Keywords: Echocardiography ; left ventricular function ; Type 1 diabetes ; metabolic control ; diabetic cardiopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cardiac function was investigated by echocardiography in 24 short-term Type 1 diabetic patients with a mean diabetes duration of 7 years (range 4–14 years) during conditions of ordinary metabolic control. Compared to 24 age and sex matched normal control subjects, measurements of myocardial contractility as left ventricular fractional shortening and mean circumferential shortening velocity were increased by 12% and 20% respectively. Another 8 Type 1 diabetic patients were examined during conditions of poor (hyperglycaemia and ketosis) and good metabolic control. Following improved glycaemic control, left ventricular fractional shortening and mean circumferential shortening velocity decreased by 16% and 24% respectively. Our findings show that short-term Type 1 diabetes is associated with increased myocardial contractility. Furthermore, this condition is related to the state of metabolic control.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 13 (1977), S. 297-303 
    ISSN: 1432-0428
    Keywords: Isolated ; perfused pancreas ; glucagon release ; calcium ; glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using the isolated, perfused canine pancreas the importance of calcium for the normal secretory function of the pancreatic alpha cell was investigated. It was found that 1. increases in perfusate Ca++ from 1.3 to 4.8 mM and from 1.3 to 8.2 mM during perfusion with glucose concentrations of 25 and 150 mg/100 ml stimulate the release of both glucagon and insulin in a dose-related and a glucose-dependent fashion. The hormone responses to increases in calcium were, with few exceptions, biphasic 2. a ‘Ca++ free’ medium inhibited release of both hormones, and increases in perfusate glucose from 25 to 150 mg/100 ml were unable to suppress glucagon or to stimulate insulin. Addition of calcium (8.2 mM) resulted in re-establishment of the normal regulatory role of glucose upon release of both hormones, now being in a hyperactivated state by the high Ca++ concentration; 3. sudden Ca++ depletion of the perfusate from 2 mM at a glucose concentration of 200 mg/100 ml inhibited immediately the release of both hormones to very low levels, which remained low until the addition of Ca++ (2 mM). Ca++ is therefore an essential requirement for the normal secretory process of pancreatic glucagon, possibly involving uptake and accumulation within the A cell, as established for the B cell. It is suggested that Ca++ exerts its effect on the microtubular microfilamentous system.
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  • 6
    ISSN: 1432-0428
    Keywords: Isolated perfused canine pancreas ; VIP ; GIP ; caerulein ; gastrin ; secretin ; glucagon ; bombesin ; acetyl choline ; adrenaline ; release of insulin ; release of glucagon ; release of PP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The release of pancreatic polypeptide (PP) by gut hormones, acetyl choline and adrenaline was investigated in an isolated perfused pancreas preparation. PP was potently released by 1 nmol/l caerulein (186±12%, p〈0.001) and gastric inhibitory peptide (GIP) (211±31%, p〈0.005) as well as by 1 [νmol/l acetyl choline (1097±59%, p〈0.001). A significant two-fold release of PP was also evoked by 1 nmol/l vasoactive intestinal peptide (VIP) (129±38%, p〈0.02 and gastrin (108±25% p〈0.01). Insulin release, induced by high glucose concentration was enhanced by both GIP (210 ±38%, p〈(0.01) and VIP (48±5%, p〈0.001). In addition GIP enhanced the release of glucagon by 179±18% (p〈0.001) at 1.4 mmol/l glucose and by 127±24% (p〈0.005) at 8.3 mmol/l glucose. Thus no simple inter-relationship appears to exist between the control of the three circulating islet hormones.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 19 (1980), S. 492-504 
    ISSN: 1432-0428
    Keywords: Pancreas ; dog pancreas ; diabetes ; somatostatin ; isolated perfused pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusions The role of cyclic AMP in the control of somatostatin release may be primarily that of a modulator without being an essential factor for initiation of somatostatin release. Much work is, however, still required to elucidate the exact nature of the role of cyclic AMP in the secretory mechanism of the D cell. All of the present evidence, however, points to a key regulatory role for calcium in the cascade of events that proceeds to the somatostatin secretion [24, 26, 30–33]. The data indicate that the changes in somatostatin secretion provoked by alterations in the extra-and intracellular levels of Na+ and K+ are secondary to changes in the intracellular level of calcium in the D cell. Caution should, however, be exercised in deducing from the results from cation fluxes in whole islets because of the mixed cell population studied. They cannot be assumed to represent the responses of the D cell alone because these cells make up only 5–15% of the total cell mass in the islet.
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  • 8
    ISSN: 1432-0428
    Keywords: Pancreas ; diabetes ; somatostatin ; glucagon ; insulin ; D-glyceraldehyde ; dihydroxyacetone ; mannoheptulose ; glucose ; arginine ; isolated perfused pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pancreatic D and A cell function is deranged in streptozotocin diabetes. To investigate this, the effect of D-glyceraldehyde, dihydroxyacetone, D-mannoheptulose and glucose variations during arginine stimulation on the release of somatostatin and glucagon from the isolated pancreas of normal and streptozotocin diabetic dogs was studied. Concentrations of the trioses, D-glyceraldehyde (1.25 and 2.5 mmol/l) and dihydroxyacetone (11 mmol/l), which normally stimulate D cells, did not influence the release of somatostatin in the diabetic dog. However, the higher concentration of D-glyceraldehyde (5 mmol/l) suppressed D cell secretion in the diabetic animals at 0 and 8.3 mmol/l glucose. A cell secretion was significantly suppressed at the higher glucose level in response to both 2.5 and 5 mmol/l of the triose. This inhibition may be explained by a non-specific effect induced by the high dose of this triose. The addition of 5 mmol/l mannoheptulose, which normally reduces glucose-induced somatostatin secretion and stimulates glucagon release, did not affect hormone secretion. In both the diabetic and the normal animals, arginine (5 mmol/l) stimulated somatostatin and glucagon secretion. Although arginine was able to stimulate D and A cell secretion in the diabetic dogs, it was however unable to restore the response to changes in glucose concentration between 1.4 and 8.3 mmol/l to normal. These results demonstrate that the abnormal pancreatic D and A cell function in streptozotocin diabetes is characterised by an impaired response to glucose and certain glucose metabolites and probably results from a specific defect in glucose recognition.
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  • 9
    ISSN: 1432-0428
    Keywords: Key words Autonomic function, diabetes mellitus, 24-h heart rate variability, microalbuminuria, sudden cardiac death, vagal function, autonomic neuropathy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The appearance of microalbuminuria in diabetic patients predicts development of macroalbuminuria and coronary heart disease. Autonomic dysfunction in ischaemic heart disease is related to an increased incidence of arrhythmic deaths. To assess sympathovagal balance in relation to microalbuminuria we performed 24-h spectral analysis of RR interval oscillations in 37 insulin-dependent diabetic patients. Patients were divided according to urinary albumin excretion as normo-(〈20 µg/min) (n =12), micro-(〉20 and 〈200 µg/min) (n =14) and macro-albuminuria (〉200 µg/min) (n =11). None had symptoms or signs of ischaemic heart disease at clinical examination or during stress testing. Fourteen matched healthy subjects served as controls. Overall RR interval variability was calculated as the 24-h standard deviation. The square root of power of the low-frequency (0.04–0.15 Hz) and high-frequency (0.15–0.40 Hz) component were considered indices of the sympathovagal interaction and vagal function, respectively. Patients with micro and macroalbuminuria had, compared to control subjects, significantly reduced 24-h standard deviation, a much smaller day/night difference in mean RR level and a significantly reduced amplitude of the low frequency and high frequency oscillations, which were even more reduced in macroalbuminuria. The differences in vagal function were also present after correction for mean RR level, and differences in physical training level and smoking. Insulin-dependent diabetic patients who develop microalbuminuria have significantly impaired vagal function and abnormal sympathovagal interaction, which is further deranged in macroalbuminuria. This early autonomic dysfunction may later contribute to a increased risk for sudden cardiac death. [Diabetologia (1994) 37: 788–796]
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  • 10
    ISSN: 1432-0428
    Keywords: Endothelin-1 ; islet of Langerhans ; mouse ; ion fluxes ; glucose ; insulin secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Endothelin-1 (ET-1), a potent endothelium-derived vasoconstrictor peptide, is secreted in response to insulin. Elevated circulating ET-1 levels have been found in patients with diabetes mellitus and vascular dysfunction. The question arises whether ET-1 acts as a direct modulator of insulin secretion. To test this, we studied the effects of ET-1 on isolated mouse islets of Langerhans. ET-1 (1 nmol/l-1 Μmol/l) dose-dependently stimulated insulin secretion from islets incubated in the presence of 16.7 mmol/l glucose (p〈0.05). The effect of ET-1 is glucose-dependent since no potentiation was found at 3.3 mmol/l glucose. Furthermore, ET-1 induced a large, transient increase in glucose-stimulated insulin secretion during islet perifusion in the presence (p〈0.001), but not in the absence, of extracellular Ca2+. The rate of 45Ca2+-efflux from 45Ca2+-prelabelled islets was transiently stimulated by ET-1 during perifusion at 16.7 mmol/l glucose in the presence of extracellular Ca2+ (p〈0.001). A short-lived increase in 45Ca2+-efflux was also observed in the absence of extracellular Ca2+ (p〈0.05). It is suggested that the effects of ET-1 on insulin secretion are critically dependent on influx via Ca2+-channels. In addition, ET-1 transiently enhanced 86Rb+-efflux from 86Rb+-prelabelled islets both in the presence (p〈0.001) and in the absence (p〈0.001) of extracellular Ca2+ suggesting that ET-1 does not elicit insulin secretion by inhibition of the potassium permeability. Our study provides evidence that ET-1 stimulates insulin secretion via a direct effect on the islets of Langerhans.
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