Biomedical subjects

G Tonolo

Publications and source records attributed to G Tonolo.

At least 19 recordsLinked to original sources

PubMed2006

Simvastatin maintains steady patterns of GFR and improves AER and expression of slit diaphragm proteins in type II diabetes.

The factors determining the course of glomerular filtration rate (GFR) and albumin excretion rate (AER) and the expression of mRNA of slit diaphragm (SD) and podocyte proteins in microalbuminuric, hypertensive type II diabetic patients are not fully understood. GFR, AER, and SD protein mRNA were studied in 86 microalbuminuric, hypertensive, type II diabetics at baseline and after 4-year random double-blind treatment either with 40 mg simvastatin (Group 1) or with 30 g cholestyramine (Group 2) per day. Both groups had at baseline a GFR decay per year in the previous 2-4 years of 3 ml/min/1.73 m(2). Both Groups 1 and 2 showed a significant decrease of low-density lipoprotein cholesterol levels after simvastatin and cholestyramine treatment (P<0.01). No change from base line values was observed as for hs-C-reactive protein and interleukin-6. A significant decrease of 8-hydroxydeoxyguanosine urinary excretion was observed after simvastatin treatment. GFR did not change from baseline with simvstatin, whereas a decrease was observed with cholestyramine treatment (simvastatin vs cholestyramine: -0.21 vs -2.75 ml/min/1.73 m(2), P<0.01). AER decreased in Group 1 (P<0.01), but not in Group 2 patients. Real-time polymerase chain reaction measurement of mRNA SD proteins (CD2AP, FAT, Actn 4, NPHS1, and NPHS2) significantly increased in kidney biopsy specimens after simvastatin, but not cholestyramine treatment. Simvastatin, but not cholestyramine, 4-year treatment maintains steady patterns of GFR, and improves AER and expression of SD proteins in type II diabetes, despite similar hypocholesterolemic effects in circulation.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2004

The role of the renin angiotensin hormonal system in the metabolic syndrome and type 2 diabetes.

Potentially important new findings have recently been reported concerning the so-called metabolic syndrome in relation to the renin-angiotensin system, ie, that treatment with inhibitors of the angiotensin-converting enzyme (ACE) not only decreases blood pressure levels but prevents the development of diabetes mellitus. The new findings described in this article highlight the potential role of the ACE system in the regulation of insulin sensitivity, thus contributing to the development of type 2 diabetes and metabolic syndrome. In addition to the well known selective effects of ACE inhibitors and angiotensin II receptor blockers in reducing microalbuminuria in diabetic patients, the potential ability of these drugs to reduce the risk of diabetes and the metabolic syndrome would support their use as first line agents not only in diabetic patients but also in selected groups of hypertensive patients, who are particularly at risk of developing metabolic complications. This information supports the Joint Guidelines for the Management of Arterial Hypertension by the European Society of Hypertension and the European Society of Cardiology, which highlight the crucial role of ACE inhibitors and the angiotensin II receptor blockers in preventing the development of diabetes in hypertensive patients.

Angiotensin Receptor Antagonists↗

PubMed2003

Plasma lipids and lipoprotein changes after biliopancreatic diversion for morbid obesity.

BACKGROUND: The reduction in plasma cholesterol with increase in large and lower dense LDL (pattern A) obtained by statins is usually associated with a prompt reduction in cardiovascular risk, but after bariatric surgery for morbid obesity a delay of some years is observed. No data regarding LDL pattern are available in obese subjects after biliopancreatic surgery. OBJECTIVE: To evaluate the modifications in LDL composition and LDL density after biliopancreatic surgery. SUBJECTS: 29 patients (17 type 2 diabetics (type 2) and 12 non-diabetics (ND)) with BMI <35, who failed previous attempts to decrease weight by diet, were studied before and 6 months after biliopancreatic diversion for morbid obesity. MEASUREMENTS: In all subjects, besides fasting circulating lipids, glucose and insulin, LDL and VLDL composition were determined and LDL density was evaluated as well. RESULTS: After surgery we observed a significant reduction of all circulating lipids, including apolipoprotein (Apo) B. The decrease was more marked for total cholesterol (-41%) than for triglycerides (-28%), without a significant difference between type 2 and ND. After surgery, LDL presented a marked decrease in the percentage of cholesterol (from 36 to 32%) with a marked increase in the percentage of triglycerides (from 13 to 18%), without appreciable modification of ApoB. After surgery, 1 patient changed from pattern B to A, while 2 patients previously pattern A became pattern B. Also a decrease in HDL and ApoAI was evident in all the subjects with an increase in the VLDL-1. CONCLUSIONS: Our data indicate that after biliopancreatic diversion, the plasma lipid profile improves along with improvement of plasma glucose and insulin sensitivity, but the LDLs become richer in triglycerides. It is possible that the greater atherogenicity of these LDLs is compensated by an improvement in the general metabolic condition.

Apolipoproteins B↗

PubMed2002

GAD65 and IA-2 autoantibodies are common in a subset of siblings of Sardinian Type 2 diabetes families.

UNLABELLED: Type 1 diabetes in Sardinia is very common in children, and we hypothesized that Latent Autoimmune Diabetes of Adult (LADA) might constitute a significant proportion of diabetes in adult Sardinian subjects. Since Type 2 diabetes is a familial disorder, we tested this hypothesis by investigating the prevalence of GAD65 and IA-2 autoantibodies (Ab) in Type 2 diabetes multiplex families of Sardinian ancestry enrolled in the Study Group for the Genetics of Diabetes in Sardinia. METHODS: A total of 684 individuals were ascertained from 252 Sardinian Type 2 diabetes multiplex families with 2.4 affected siblings per family comprising 190 families with two affected, 37 with three, 15 with four, 7 with five, and 3 with six, in addition to 80 unaffected siblings. Controls were household contacts representing 204 healthy spouses of affected siblings. Diagnosis was at 35-69 years of age and insulin was not given in the first 4 years after diagnosis. GAD65Ab and IA-2Ab were determined in standard radioligand binding assays. RESULTS: Among affected siblings GAD65Ab were positive in 8.8% of insulin-treated (n = 137; P = 0.0006), in 2.5% of non-insulin-treated (n = 467), and in 1.2% of non-diabetic siblings (n = 80) compared with 0.5% of controls (n = 204). IA-2Ab was positive in 6.6% insulin-treated (P = 0.04), 2.1% non-insulin-treated, and 2.5% non-diabetic siblings compared with 1.5% of controls. CONCLUSION: A high frequency of GAD65Ab and IA-2Ab as markers of Type 1 diabetes was found among Type 2 diabetes siblings from Sardinian multiplex families despite excluding those who had been treated with insulin during the first 4 years of disease. Our data support the hypothesis that LADA may be common in Sardinian Type 2 diabetes and stress the importance of investigating markers of Type 1 diabetes in studies of Type 2 diabetes.

Adult↗

PubMed2002

Low-dose dexamethasone in the rat: a model to study insulin resistance.

The main aim of this study was to set up a new animal model to study insulin resistance. Wistar rats (6 or 7 per group) received the following for 4 wk in experiment 1: 1) vehicle, 2) 2 microg/day subcutaneous dexamethasone, 3) metformin (400 mg x kg(-1) x day(-1) os), and 4) dexamethasone plus metformin. In experiment 2 the rats received the following: 1) vehicle, 2) dexamethasone, 3) dexamethasone plus arginine (2%; as substrate of the nitric oxide synthase for nitric oxide production) in tap water, and 4) dexamethasone plus isosorbide dinitrate (70 mg/kg; as direct nitric oxide donor) in tap water. Insulin sensitivity was significantly reduced by dexamethasone already at week 1, before the increase in blood pressure (day 15) and without significant changes in body weight compared with vehicle. Dexamethasone-treated rats had significantly higher triglycerides, hematocrit, and insulin, whereas serum total nitrates/ nitrites were lower compared with vehicle. The concomitant treatment with metformin minimized all the described effects of dexamethasone. In experiment 2, only isosorbide dinitrate was able to prevent the observed dexamethasone-induced metabolic, hemodynamic, and insulin sensitivity changes. Chronic low-dose subcutaneous dexamethasone (2 microg/day) is a useful model to study the relationships between insulin resistance and blood pressure in the rat, and dexamethasone might decrease insulin sensitivity and increase blood pressure through an endothelium-mediated mechanism.

Animals↗

PubMed2001

Identification of a new mutation in the alpha4(IV) collagen gene in a family with autosomal dominant Alport syndrome and hypercholesterolaemia.

BACKGROUND: Alport syndrome (AS) is a hereditary disease of the glomerular basement membrane in the kidney characterized by progressive renal failure, sensorineural deafness, and/or ocular abnormalities. In contrast to the well-known X-linked phenotype, very little is known about the autosomal dominant form. Rare autosomal forms of AS have been described with mutations in COL4A3 and COL4A4 at chromosome region 2q35-q37, but there have been no descriptions of dominant forms due to a mutation in COL4A4. METHODS: We describe a Sardinian family with a classical AS-phenotype plus hypercholesterolaemia, a clinical feature also present in Fechtner syndrome (FS), a disease that segregates as an autosomal dominant trait. RESULTS: A suggestive linkage (LOD=2.7) between AS and the COL4A3/A4 locus at 2q35-q37 was identified. Other candidate collagen genes encoding basement membrane collagen (COL4A1/A2 and COL4A5/A6) were excluded by linkage analysis (13q33-q34 and Xq22), or by sequence (COL4A3). DNA sequence analysis of the COL4A4 gene revealed that the Lys325Asn mutation was present in all affected family members, but was absent in all unaffected members and in a random sample of the Sardinian population. A clear indication of a gene-dosage effect was seen in the most severely affected family member, since she carried the mutation in the homozygous form. CONCLUSIONS: These data confirm the importance of collagen 4A4 as a component in the structural integrity of the glomerular basement membrane and confirm the phenotypic and genetic heterogeneity of collagen disorders.

Adult↗

PubMed2000

Additive effects of Simvastatin beyond its effects on LDL cholesterol in hypertensive type 2 diabetic patients.

BACKGROUND: Experimental evidence indicates that statins might have direct vascular effects independently from low-density lipoprotein (LDL) cholesterol reduction and we reported that the reduction in urinary albumin excretion rate during Simvastatin treatment in type 2 diabetic patients was not correlated with LDL-cholesterol decrease. However in humans there are no data regarding possible additional effects of Simvastatin on blood pressure and urinary albumin excretion beyond its capacity to lower serum cholesterol. PATIENTS AND METHODS: Twenty-six microalbuminuric hypertensive type 2 diabetic patients (diastolic blood pressure - after four months wash-out from the previous antihypertensive therapy - consistently > 90 and < 100 mmHg; plasma LDL-cholesterol > 3.9 and < 6.5 mmol L-1) were enrolled in the study. In random order, these patients received Simvastatin (20 mg day-1) or Cholestyramine (6 g three times a day) for a period of 10 months and after three months of wash-out (cross-over) the sequence was reversed for an additional 10 months. Blood pressure, lipid parameters, glycated haemoglobin and urinary albumin excretion were measured during the study. Additionally, in eight patients, urinary glycosaminoglycan excretion (GAG) was also measured during the study. RESULTS: Simvastatin and Cholestyramine were equally effective in reducing total and LDL cholesterol. Only during Simvastatin treatment a significant reduction in diastolic blood pressure and both 24 h urinary albumin and GAG excretion rates were observed, while no significant changes were seen with Cholestyramine treatment. CONCLUSIONS: Our results clearly show for the first time that the reduction of blood pressure, together with 24 h urinary albumin excretion rate - two established cardiovascular risk factors, obtained during Simvastatin therapy in hypertensive type 2 diabetic patients - is in large part independent from the reduction of LDL Cholesterol.

Albuminuria↗

PubMed2000

A new locus for autosomal recessive hypercholesterolemia maps to human chromosome 15q25-q26.

High serum cholesterol is an established risk factor for cardiovascular disease and is the prime target for therapeutic intervention in large groups of patients. The development of modern treatments for this major risk factor was propelled by the early realization that forms of severe hypercholesterolemia could be caused by dominantly inherited defects in the LDL receptor or in the APOB gene. Further understanding of the mechanisms contributing to early atherosclerosis will allow for new targets for therapy. We therefore identified and investigated the genetics of families from Sardinia that have recessive inheritance of precocious hypercholesterolemia. We used five families in an analysis of linkage of the autosomal recessive hypercholesterolemia locus, termed "ARH1," to chromosome 15q25-q26. A genomewide search mapped the disease-causing gene with a LOD score of 3.3 and excluded major contributions to the phenotype of other genes. A candidate gene present in the mapped chromosome region-the ligand-activated liver-transcription-factor gene ARP1 (apolipoprotein regulatory-protein gene)-has been excluded after DNA sequencing. The close-bred nature of the Sardinian population offers unique opportunities for isolation of this hypercholesterolemia-causing gene.

Adolescent↗

PubMed1999

High plasma prorenin in non diabetic siblings of non insulin-dependent diabetes mellitus patients.

In a large cohort (no. = 361) of NIDDM probands and their concordant/discordant siblings from no. = 132 families we studied: 1. the levels of plasma prorenin in non affected siblings of NIDDM probands as opposed to normal subjects without family history of diabetes, and 2. whether plasma prorenin raises in parallel to urinary protein loss in NIDDM patients. Prorenin (solid-phase trypsin) and micro-macroalbuminuria (radioimmunoassay) were evaluated. Plasma prorenin was higher in NIDDM probands and siblings than in non NIDDM siblings (37+/-31 vs. 25+/-15 ng/ml/h, p<0.0005) who, in turn, showed higher plasma prorenin than non diabetic controls without family history of diabetes (25+/-15 vs. 17+/-8 ng/ml/h, p<0.005). Plasma prorenin was higher in NIDDM siblings of micro-macroalbuminuric probands than in NIDDM siblings of non micro-macroalbuminuric probands (40+/-26 vs. 29+/-20 ng/ml/h, mean +/- SD, p = 0.0058) whereas no difference was found among non diabetic siblings (24+/-14 vs. 22+/-11 ng/ml/h, NS). Our data confirm that plasma prorenin is elevated in NIDDM patients, and show: 1. that the raise of plasma prorenin in non-NIDDM siblings of a diabetic patient does not depend entirely from the presence of diabetes, and 2. that plasma prorenin in NIDDM probands and their concordant siblings goes along with micro-macroalbuminuria.

Blood Pressure↗

PubMed1999

Lipoprotein metabolism during normal pregnancy.

OBJECTIVE: We sought to investigate the changes in circulating serum lipids and lipoproteins, including lipoprotein (a), and low-density lipoprotein size in women during normal pregnancy. STUDY DESIGN: Twenty-two women (mean age, 31 +/- 5 years; 13 primiparous subjects) were studied during uncomplicated pregnancy with normal outcome. Twenty-four nulliparous women of similar age (31 +/- 4 years) were studied as control subjects. RESULTS: Serum triglycerides and total and low-density lipoprotein cholesterol increased significantly during pregnancy in all women. Women with changes in low-density lipoprotein during the second and third trimesters showed a more marked increase in serum triglycerides, and this effect was slightly more evident in the multiparous subjects. No other differences were evident between primiparous and multiparous women apart from high-density lipoprotein cholesterol levels, which were slightly decreased in the latter subjects. CONCLUSIONS: Our results show that during normal pregnancy, the increase in plasma triglycerides may lead to the appearance of the atherogenic dense low-density lipoproteins in a subgroup of women. We suggest that the observed changes in low-density lipoprotein patterns during pregnancy might be used to identify those women who later in life will have these atherogenic small and dense low-density lipoproteins.

Adult↗

PubMed1999

Polymorphisms of angiotensin-converting enzyme and angiotensinogen genes in type 2 diabetic sibships in relation to albumin excretion rate.

Familial clustering of altered albumin excretion and nephropathy risk has been described in both type 1 and type 2 diabetes; moreover, an association of micro-macroalbuminuria and diabetic retinopathy has been recently reported in a large number of white families with type 2 diabetes. Conflicting reports, mainly comparing affected with unaffected unrelated subjects, have suggested a possible role of some genotypes of the renin-angiotensin system in conferring nephropathy risk in type 2 diabetes. To examine the role of genetic factors in influencing albuminuria in families, we studied the relation of angiotensin-converting enzymes (ACE) and angiotensinogen (AGN) genotypes with albumin excretion rate in a population of affected siblings of type 2 diabetic probands. We determined ACE insertion/deletion polymorphism and two polymorphisms of the AGN gene (T174M and M235T) in 160 families with at least one affected member. Defining proband as the patient with the longest known duration of diabetes, we compared the allelic distribution in diabetic probands with and without altered albumin excretion and in their siblings. Allelic distribution of these polymorphisms was similar in the two groups of probands, as well as in their siblings. Identity-by-State (IBS) analysis showed a link between AGN locus and arterial hypertension in these siblings, which was independent from the degree of renal involvement. Thus, our findings suggest that in white families with type 2 diabetes, there is no linkage between the degree of albumin excretion and ACE and AGN polymorphisms, whereas the latter is related to arterial hypertension, as previously found in patients without diabetes but with essential hypertension.

Albuminuria↗

PubMed1999

Association of Trp64Arg beta 3-adrenergic-receptor gene polymorphism with essential hypertension in the Sardinian population.

OBJECTIVE: To evaluate the possible association of three candidate gene polymorphisms with essential hypertension in the genetically homogeneous Sardinian population. SUBJECTS AND METHODS: We studied 494 unrelated, nondiabetic subjects, 213 (43.2%) with essential hypertension. All subjects underwent a 75 g oral glucose tolerance test with determination of glycemia and insulinemia and serum lipids. The polymorphisms evaluated comprised Trp64Arg of the beta 3-adrenergic receptor, Gly40Ser of the glucagon receptor gene and the insertion/deletion polymorphism of the angiotensin converting enzyme (ACE) gene. RESULTS: Among the overall population studied, 48 (9.7%) were heterozygous carriers of the Trp64Arg polymorphism. The frequency of the Trp64Arg variant was significantly higher in hypertensives (13.6%) than normotensives (6.8%; chi 2 5.73, P = 0.017). The 48 subjects with the Trp64Arg variant had significantly higher (P < 0.049) serum triglyceride levels than the 446 with the Trp64Trp variant, while no significant differences were observed, either fasting or during the 75 g oral glucose tolerance test, in glycemia and insulinemia. No differences were found between hypertensive and normotensive subjects for ACE gene insertion/deletion polymorphism nor in the frequency of the Gly40Ser coding change in exon 2 of the glucagon receptor gene. CONCLUSIONS: Our results are consistent with the thesis that the Trp64Arg polymorphism of the beta 3-adrenergic receptor gene is associated more often with the condition of high blood pressure than with normal blood pressure.

Alleles↗

PubMed1998

Serum apolipoprotein(a) concentrations and Apo(a) phenotypes in patients with liver cirrhosis.

OBJECTIVE: The liver is the major site of apolipoprotein(a) synthesis, and an inverse correlation between the size of apolipoprotein(a) isoforms and its serum levels have been described. We evaluated the Apo(a) serum levels and its isoforms in patients with liver cirrhosis at different stages of the disease (Childe Turcotte classification), and during the characteristic phase of liver synthesis decline. METHODS: We studied 84 patients with liver cirrhosis and 185 control subjects with normal liver function. RESULTS: Apo(a) serum levels were significantly lower (p < 0.01) in cirrhotic patients and, after 24 months, six patients showing a change from class A to class B had a statistically significant decrease in Apo(a) concentrations (p = 0.0313). Moreover, our data showed an inversion of the small/large isoforms ratio in patient with cirrhosis in spite of the reduction in plasma concentration. CONCLUSION: We showed a reduction of Apo(a) serum concentrations in a large number of patients with cirrhosis and, for the first time, during the characteristic phase of liver synthesis decline, confirming the liver as the major site of Apolipoprotein(a) synthesis. Moreover we showed in the cirrhotic patients that the normal correlation between Apo(a) isoforms and Apo(a) concentrations is not conserved and the low levels are not dependent upon a high prevalence of large isoforms.

Apolipoproteins A↗

PubMed1998

Insulin sensitivity and glucose effectiveness: minimal model analysis of regular and insulin-modified FSIGT.

The minimal model is widely used to evaluate insulin action on glucose disappearance from frequently sampled intravenous glucose tolerance tests (FSIGT). The common protocols are a regular (rFSIGT, single injection of 0.3 g/kg of glucose) and an insulin-modified test (mFSIGT, with an additional insulin administration at 20 min). This study compared the insulin sensitivity index (SI) and glucose effectiveness (SG) obtained in the same individual (16 normal subjects) with the two tests. SI was 7.11 +/- 0.80 10(-4).min-1.microU-1.ml in rFSIGT and 6.96 +/- 0.83 in mFSIGT (P = 0.656), regression r = 0.92, P < 0.0001; SG was 0.0260 +/- 0.0028 min-1 and 0.0357 +/- 0.0052, respectively, statistically different (P = 0.013) but still with a good regression (r = 0.66, P = 0.0051). SG and insulin amount during the early period correlated (r = 0.6, P = 0.015 in rFSIGT and r = 0.76, P = 0.0006 in mFSIGT). In summary, both FSIGTs with minimal model analysis provide the same SI, which is a very robust index. SG was different by 28% due probably to the relationship between SG and the amount of circulating insulin. In studies comparing groups, the simpler rFSIGT can still be used with the advantage of accounting for endogenous insulin, thus offering the possibility of direct inferences on the beta-cell activity.

Adult↗

PubMed1998

Biliopancreatic diversion for treatment of morbid obesity: experience in 50 cases.

BACKGROUND: Biliopancreatic diversion (BPD) by Scopinaro's method is an operation advocated by some surgeons as an effective treatment for morbid obesity. METHODS: Between February 1995 and April 1997 we performed BPD by Scopinaro's method on 50 patients with morbid obesity (23 males), average age 41.4 years (range 20-63 years), average body weight 135.08 kg (range 89-256 kg), mean body mass index (BMI) 50.65 kg/m2 (range 37.01-81.56 kg/m2). RESULTS: In all cases a gradual decrease in weight was obtained [mean BMI at 1 month: 44.8 kg/m2, at 6 months (31 patients): 35.09 kg/m2, at 1 year (23 patients): 31.36 kg/m2, at 18 months (14 patients): 29.89 kg/m2 and at 2 years (5 patients): 29.27 kg/m2]. At the same time a significant improvement in the pathological conditions associated with morbid obesity was observed. The patients were able to suspend oral antihypertensive and antidiabetic therapy as these parameters spontaneously returned to normal values by the sixth postoperative month; all cases showed a marked reduction in hypercholesterolemia and hypertriglyceridemia. Postoperative complications were: one death (2%) on the third day due to heart failure; two late intestinal occlusions (4%); one acute dilatation of the stomach (2%); one peritonitis caused by early dehiscence of the anastomosis (2%); five anastomotic ulcers (10%); two cases of protein malnutrition (4%). CONCLUSIONS: BPD by Scopinaro's method is a bariatric procedure which is technically complex. However is it safe and reproducible and it induces a substantial weight loss.

Adult↗

PubMed1998

Biliopancreatic diversion preserving the stomach and pylorus in the treatment of hypercholesterolemia and diabetes type II: results in the first 10 cases.

BACKGROUND: Besides weight loss Scopinaro's operation produces correction of hypercholesterolemia and noninsulin dependent diabetes mellitus in all patients who suffer from these conditions. These results encouraged us to perform biliopancreatic diversion (BPD) without gastric resection, thus preserving the functions of the stomach and pylorus in moderately overweight patients with hypercholesterolemia associated with diabetes type II and hypertriglyceridemia. METHODS: Between March 1996 and July 1997 we performed BPD without gastric resection on 10 moderately overweight patients [mean body mass index (BMI) = 33.2 kg/m2]. All patients had suffered from hypercholesterolemia and hypertriglyceridemia for more than 5 years. Ten patients suffered from diabetes type 11; four of them had had insulin treatment or oral anti-diabetic agents; the other patients all had hyperglycaemia in the fasted state and diabetes confirmed by preoperative oral glucose tolerance test (OGTT). Five patients suffered from hypertension. RESULTS: In all patients, cholesterol and triglyceride levels returned to normal within the first postoperative month. Glycemia also stabilized at normal values in nine patients within the early weeks after surgery. One patient who took 70 U of insulin reduced his daily intake to 35 U 2 months postoperatively. In all patients blood pressure returned to normal. Weight loss was predictably slight (10-15 kg). CONCLUSIONS: Our experience with the procedure found that this new method seems to be as effective in controlling lipidic metabolism and diabetes II as the original version of BPD. As expected, weight loss is only moderate, so that the modified BPD is not suitable for very obese patients.

Adult↗

PubMed1997

Physiological and genetic characterization of the Gly40Ser mutation in the glucagon receptor gene in the Sardinian population. The Sardinian Diabetes Genetic Study Group.

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.

Aged↗

PubMed1997

Clustering of albumin excretion rate abnormalities in Caucasian patients with NIDDM. The Italian NIDDM Nephropathy Study Group.

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 A1c 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) micrograms/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.

Albuminuria↗