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Notes: Summary A Gly40Ser amino acid substitution in the glucagon receptor gene has been associated with non-insulin-dependent diabetes mellitus (NIDDM), but the questions raised about its physiological implications have not been resolved. The aim of this study was to determine the frequency of the Gly40Ser mutation in different regions of Sardinia and to investigate the physiological implications of the mutation in glucose and insulin homeostasis. We studied a population of 691 subjects, selected on the basis of their Sardinian origin. Only heterozygous subjects were found, 21 of 574 (3.6 %) in NIDDM patients and 5 of 117 in non-diabetic subjects (4.2 %). In northern Sardinia 3.4 % of the NIDDM patients were carriers of the Gly40Ser substitution, 1.4 % in central Sardinia, while 7.6 % carried the substitution in the Southern part. No significant differences were found between hypertensive and normotensive subjects with respect to the presence of Gly40Ser. Ten subjects with Gly40Ser were carefully matched for diabetic state, BMI, age, sex, and geographical origin with 10 patients with Gly40, and a glucagon infusion test was performed using 1, 3, 9 and 27 ng glucagon kg–1· min–1 for 30 min. Blood for determination of glucose, glucagon, and insulin concentrations was drawn at 15-min intervals from the Controlateral arm. Plasma glucagon increased dose-dependently during the infusion with no significant difference between the two groups. Carriers of Gly40Ser had a significantly lower (p 〈 0.02) increase in plasma glucose concentration in response to glucagon infusion compared to Gly40 homozygous subjects at all times, while the plasma insulin increase was not significantly different at any time. In conclusion, our results indicate that the Gly40Ser variation is not associated with NIDDM in the Sardinian population, and that its frequency varies in different parts of Sardinia. Moreover in vivo Gly40Ser plays a physiological role in the glucose homeostasis under glucagon control both in NIDDM and non-diabetic subjects. This latter result suggests that this amino acid substitution in the glucagon receptor may lead to a decreased blood glucose concentration because of the reduced stimulation of liver glucose output via the glucagon receptor. [Diabetologia (1997) 40: 89–94]

Notes: Abstract We describe cases of isolated functioning insulinoma occurring in two members of the same family (father and daughter). The father had a first encapsulated insulinoma diagnosed at 14 years of age and at the age of 33 years he was operated on for a second insulinoma infiltrating the exocrine pancreas with lymph node metastases. The daughter was operated on for an encapsulated insulinoma in the tail of the pancreas when she was 6 years old. No clinical and laboratory signs of other endocrine disturbances have so far been detected in either care or in any other members of the family. Our report suggests the possibility of multiple familial insulinoma, although this is an extremely rare condition. Our data also indicate that insulinomas, even if well controlled by medical treatment, should always be removed by surgery because malignancy cannot be excluded with certainty. Moreover, patients should be closely followed up, as recurrence may develop up to 15 years after surgery.

Notes: Abstract The plasma lipid changes commonly observed in patients with diabetic nephropathy may play a major role in determining the increased cardiovascular risk in these patients. Contrasting results have been reported on the patterns of lipids and lipoproteins in diabetic subjects with microalbuminuria. We examined 20 patients with type 1 (insulin-dependent) diabetes who had a urinary albumin excretion 〉30 mg/24 h (11 males and 9 females, age range 16–45 years, mean diabetes duration 11.7 years) and 20 type 1 diabetic patients without microalbuminuria matched for sex, age, diabetes duration, daily insulin requirement and degree of metabolic control. In all patients we measured plasma total cholesterol, highdensity lipoprotein (HDL)-cholesterol, triglycerides, apolipoproteins A1 and B and lipoprotein (a) [Lp(a)]. No significant differences were found for any parameter between subjects with a urinary albumin excretion 〈20 mg/ 24 h and microalbuminuric patients. Moreover in nondiabetic controls the levels of plasma Lp(a) and of the other parameters measured were not significantly different from those of the two diabetic groups. Our results suggest that in type 1 diabetic patients with fairly good glycaemic control microalbuminuria is not associated with significant changes in the lipoprotein pattern.

Notes: Abstract A significantly different prevalence in the Gly40Ser variant of the glucagon receptor gene in a small group of essential hypertensive patients compared with normotensive probands was described in a Caucasian population. It has been postulated that this variant may exacerbate the antinatriuretic effect of high plasma insulin levels commonly seen in hypertensive subjects, leading to volume expansion and rise in blood pressure level. The aim of this study was to evaluate the prevalence of the Gly40Ser variant in a population of 404 non-insulin-dependent diabetic patients of Sardinian origin. No association of the Gly40Ser variant with hypertension was seen in this large population.

Notes: Summary Progressive capillary occlusion often leads to severe retinopathy within 15–20 years of the onset of Type 1 (insulin-dependent) diabetes mellitus. Lipoprotein (a), a complex formed by apolipoprotein (a), apo B-100 and lipids, is considered an independent, genetically determined, predictor of cardiovascular disease. It may have antifibrinolytic properties in view of its similarity to plasminogen. To test the hypothesis that circulating lipoprotein (a) is associated with the process that leads to clinically active diabetic retinopathy, we measured the circulating levels of apolipoprotein (a) (which are strictly correlated with those of lipoprotein (a)) in two groups of patients with Type 1 diabetes of at least 15 years duration: 25 with active retinopathy and 27 without clinically detectable retinal lesions. Thirty-eight healthy subjects of the same age and sex served as controls. Serum apolipoprotein (a) was higher in the patients with active retinopathy (36(2-193) U/dl, geometric mean and range) than in those without clinically detectable retinal lesion (17(1–160)) and the control subjects (14(0–115)), p 〈 0.01 in both cases. The distribution of apolipoprotein (a) levels was skewed to the left, as expected, in the patients without clinically evident retinal lesions and the control groups, but there was a bimodal trend of distribution among those with active retinopathy. The levels of glycated haemoglobin were similar in the two groups of diabetic patients, and no significant differences were found for total and HDL cholesterol, triglycerides or apolipoproteins A1 and B between them and the control subjects. These preliminary results suggest that serum apolipoprotein (a) is elevated in patients with active retinopathy. The role of this lipoprotein as a predictor or a pathogenic effector of diabetic retinopathy, or both deserves further investigation.

Notes: Summary Proteinuria and nephropathy have been found to cluster in families of non-insulin-dependent diabetic (NIDDM) Pima Indian, and in Caucasian insulin-dependent diabetic (IDDM) patients. No information is at present available for Caucasian NIDDM patients. The aim of the present study was to determine whether micro-macroalbuminuria (AER + ) is associated with albumin excretion rate abnormalities in diabetic and non-diabetic siblings of probands with NIDDM and AER + . We identified 169 Caucasian families with one NIDDM proband (the patient with longest known NIDDM duration) (101 families with only NIDDM siblings, 33 families with both NIDDM and non-NIDDM siblings and 35 families with only non-NIDDM siblings). Of the probands 56 had AER + [Prob-NIDDM-(AER + )], 78 had AER– [Prob-NIDDM-(AER–)], 74 siblings of Prob-NIDDM-(AER + ), and 113 siblings of Prob-NIDDM-(AER–) also had NIDDM. Data on albuminuria and retinopathy from multiple sibling pairs when the size of the sibship was more than two was adjusted according to a weighting factor. The odds ratio for AER + , in siblings of Prob-NIDDM-(AER + ) adjusted for age, hypertension, glycated haemoglobin A1 c and other confounding variables was 3.94 (95 % confidence intervals: 1.93–9.01) as compared to siblings of Prob-NIDDM-(AER–). The 74 siblings of Prob-NIDDM-(AER + ) had higher prevalence of proliferative retinopathy than siblings of Prob-NIDDM-(AER–) (14 vs 2 %; p 〈 0.01). We also identified 66 non-diabetic siblings of 41 NIDDM probands with AER + and 36 non-diabetic siblings of 27 NIDDM probands with AER–. Albumin excretion was two times higher, although still within the normal range, in the non-diabetic siblings of Prob-NIDDM-(AER + ) than in siblings of Prob-NIDDM-(AER–) [median = 13.5 (range 0.5–148) vs 6.6 (range 1–17) μg/min (p 〈 0.05)]. In conclusion higher rates of albumin excretion aggregate in Caucasian families with NIDDM. Proliferative retinopathy is more frequently observed in families showing a clustering of AER + and NIDDM. These findings suggest that familial factors play a role in the pathogenesis of renal and retinal complications in NIDDM. [Diabetologia (1997) 40: 816–823]

Notes: Summary Pathogenetic mechanisms other than the quality of metabolic control may play a role in the development of diabetic nephropathy. Some cross-sectional studies have shown that elevated erythrocyte sodium-lithium countertransport (Na + /Li + CT) activity may be linked to incipient or overt nephropathy in insulin-dependent diabetic (IDDM) patients. The aim of the present work was to ascertain if high erythrocyte Na + /Li + CT activity anticipates the development of microalbuminuria in IDDM patients. Evaluation of this cation transport system was carried out in 159 normotensive, normoalbuminuric IDDM patients, who were divided into two groups: those with values above (Group A) and those with values below (Group B) the median level in the overall population (300 μmol/erythrocytes × h). A total of 79 patients in Group A and 80 in Group B underwent periodic examinations over a similar time period (5.2 years, range 3.3–7.4 years and 5.4 years, range 3.4–7.5 years, respectively). Median sodium-lithium countertransport activity was stable when evaluated after 2 and 4 years of follow-up. Only seven patients were excluded from the protocol because changes in their sodium-lithium countertransport activity placed them on the other side of the median value with respect to their baseline measurement. Thus, 152 patients completed the study (76 in Group A and 76 in Group B). Of the 76 patients in Group A, 17 developed persistent microalbuminuria (22.3 %). The number of patients in Group B showing persistent microalbuminuria was significantly lower (4 of 76; 5.2 %; p 〈 0.01). The sensitivity of erythrocyte Na + /Li + CT in predicting the development of microalbuminuria was 85 % and its specificity was 55 %. Seven patients of Group A and five of Group B developed arterial hypertension. Subjects in Group A had significantly higher mean HbA1 c values of twice yearly measurements than those in Group B (9.6 ± 1.7 vs 8.3 ± 1.7 %, p 〈 0.002, mean ± SD) despite similar daily insulin requirements. Systolic and diastolic blood pressure levels were also evaluated every 6 months and were significantly higher in the Group A than in the Group B patients, although on average within the normal range. The odds ratio for developing persistent microalbuminuria in IDDM with elevated baseline erythrocyte Na + /Li + CT activity after adjustment for gender and baseline albumin excretion rate, and mean 6 monthly plasma creatinine, HbA1 c and systolic and diastolic blood pressure levels was 4.2 (95 % confidence intervals 2.0–11.1). It was also found that the percentage of offspring having both parents with Na + /Li + CT activity above the median value was significantly higher in Group A than in Group B (Group A vs Group B: 35 vs 19 %; p 〈 0.01). On the contrary the percentage of offspring whose erythrocyte Na + /Li + CT was lower in both parents was lower in Group A than in Group B: 10 vs 38 %, p 〈 0.01). Parents of Group A offspring had arterial hypertension more frequently than those of Group B. These results indicate that erythrocyte Na + /Li + CT activity is a useful diagnostic tool in identifying normotensive, normoalbuminuric patients who may be predisposed to develop persistent microalbuminuria. This disorder in the cation transport system is associated with poor metabolic control, higher blood pressure, and male sex; it also appears to be, at least partly, genetically transmitted. [Diabetologia (1997) 40: 654–661]

Notes: Abstract We complete and correct some proofs of an earlier paper on distributional Borel summability and we add an application which can be useful in the discussion of semiclassical problems.

Notes: Abstract We prove that the Stark effect perturbation theory of a class of bound states uniquely determines the position and the width of the resonances by Distributional Borel Sum. In particular the small field asymptotics of the width is uniquely related to the large order asymptotics of the perturbation coefficients. Similar results apply to all the “resonances” of the anharmonic and double well oscillators.