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Biomedical subjects

G C Viberti

Publications and source records attributed to G C Viberti.

At least 19 recordsLinked to original sources
PubMed2006

Metabolic syndrome in obese Caucasian children: prevalence using WHO-derived criteria and association with nontraditional cardiovascular risk factors.

OBJECTIVE: Studies on the prevalence of metabolic syndrome (MS) in European obese children using child-based criteria are scanty. Moreover, it is unknown if nontraditional cardiovascular disease (CVD) risk factors are associated with the MS at this early age in these subjects. DESIGN AND SUBJECTS: We studied the prevalence of the MS in 588 Caucasian obese children and adolescents by devising a World Health Organization derived definition and child-specific criteria, whose deviation from normalcy was based on an age, sex, and ethnically comparable control group of 1363 subjects. In a subgroup of 206 obese children, we investigated the association of the MS with nontraditional CVD risk factors. MEASUREMENTS: Fasting blood samples for glucose and lipids measurements were taken in both control and obese children. In addition, the obese children underwent an oral glucose tolerance test. In the subgroup of 206 obese children, albumin excretion rate , plasma uric acid, fibrinogen, plasminogen activator inhibitor type 1(PAI-1), C-reactive protein, interleukin 6 and white blood cells were also measured. RESULTS: The prevalence of MS was 23.3%. A similar prevalence of 23% of MS was recorded in the subgroup of 206 obese children in whom measurements of nontraditional CVD risk factors were available. After adjustment for the degree of obesity, subjects with MS had significantly higher uric acid (6.6+/-0.23 vs 6.1+/-0.12 mg/dl, P<0.0001) and PAI-1 plasma concentrations (231.4+/-25.50 vs 214.3+/-12.96 ng/ml, P<0.05) and a higher frequency of microalbuminuria (37 vs 20%, P<0.05) than those without MS. Microalbuminuria, uric acid and PAI-1 explained 10.6% of the variance of MS. CONCLUSION: Approximately, a quarter of Caucasian obese children have the MS. The association of MS with several nontraditional risk factors for CVD early in life suggests a heightened CVD risk in these individuals.

Adolescent↗
PubMed2003

P38 mitogen-activated protein kinase mediates hexosamine-induced TGFbeta1 mRNA expression in human mesangial cells.

AIMS/HYPOTHESIS: The hexosamine pathway has been implicated in the induction of TGFbeta1 expression and in the pathophysiology of diabetic glomerulopathy. Glucose-induced TGFbeta1 expression is mediated by p38 mitogen-activated-protein-kinase (p38-MAPK) and this kinase is activated in the diabetic glomeruli. We examined whether the p38-MAPK is implicated in hexosamine-induced TGFbeta1 mRNA expression in human mesangial cells. GFAT overexpression induced an increase in p38-MAPK activation after 6 and 12 h incubation in normal glucose, and this was prevented by the GFAT inhibitor azaserine. Furthermore, high glucose enhanced p38-MAPK activation in GFAT tranfected cells ( p</=0.04). P38-MAPK inhibition using SB202190 (1 micro mol/l) reduced hexosamine-induced TGFbeta1 expression in normal and high glucose. The activation of the p38-MAPK was dependent on protein kinase-C. METHODS: The products of the hexosamine biosynthetic pathway were increased by the addition of glucosamine or by the overexpression of the rate-limiting enzyme of the hexosamine pathway, glutamine: fructose-6-phosphate amidotransferase (GFAT). RESULTS: Glucosamine addition resulted in cell death. UDP-N-Acetylglucosamine, one of the major hexosamine end-products, was increased in normal (7 mmol/l) and high (25 mmol/l) glucose conditions in GFAT-transfected cells compared to control transfected cells by twofold and 1.7-fold respectively ( p</=0.04) and this was accompanied by a 1.6- and 2.3-fold increase ( p</=0.02) in TGFbeta1 mRNA expression. Addition of the GFAT inhibitor azaserine (10 micro mol/l) prevented the induction of TGFbeta1 in GFAT transfected cells. CONCLUSION/INTERPRETATION: Overexpression of GFAT increases hexosamine accumulation which mediates TGFbeta1 expression via a protein kinase-C and p38-MAPK dependent mechanism. Increased glucose concentrations magnify these effects.

Cells, Cultured↗
PubMed2003

Rosiglitazone: potential beneficial impact on cardiovascular disease.

Rosiglitazone, a potent member of the thiazolidinedione class of oral antidiabetic agents, reduces hyperglycaemia by improving insulin sensitivity--an important underlying factor in the development of both type 2 diabetes and its related cardiovascular complications. Rosiglitazone has now been available in clinical practice for more than three years, so there is a large body of evidence supporting its efficacy and safety as an antihyperglycaemic agent in patients with type 2 diabetes. Given the significant burden imposed on patients and healthcare resources by diabetes-related cardiovascular disease (CVD), there is growing interest in the thiazolidinediones in terms of their potential to ameliorate CVD risk factors as a result of their insulin-sensitising action and thus improve cardiovascular outcomes in individuals with type 2 diabetes. As reviewed below, rosiglitazone has a beneficial impact on a number of factors associated with insulin resistance and CVD, including microalbuminuria, hypertension, dyslipidaemia, visceral fat, elevated plasminogen activator inhibitor-1 levels and increased concentrations of C-reactive protein. These thiazolidinedione compounds are not problem-free and the long-term implications of some of rosiglitazone side-effects such as weight gain, changes in LDL-cholesterol concentration and fluid retention remain to be resolved. Large-scale clinical outcome studies should give a clearer picture for rosiglitazone and related thiazolidinediones in relation to the extent of their impact on diabetes disease progression and incident cardiovascular events.

Albuminuria↗
PubMed2002

The Decorin gene 179 allelic variant is associated with a slower progression of renal disease in patients with type 1 diabetes.

UNLABELLED: Background genetic factors may influence the variability in the rate of progression of kidney disease in type 1 diabetes. In diabetes, progressive mesangial matrix expansion and glomerular sclerosis are, to a large extent, mediated by TGF-beta1. Decorin, a proteoglycan which is a component of the extracellular matrix, regulates TGF-beta1 activity and expression. We have examined the relationship between the 179/183/185 polymorphism of the Decorin gene and the progression of diabetic nephropathy. METHODS: From a cohort of 175 European patients with diabetic nephropathy, we studied 79 patients who were selected because they had a follow-up of at least 2 years (average 6.5 years; range: 2.5-15 years), and regular measurements of serum creatinine on 5 or more occasions. Creatinine clearance (CrCl) calculated from serum creatinine concentration was used as a measure of derived glomerular filtration rate (dGFR). All patients were on antihypertensive therapy. RESULTS: The rate of dGFR decline in the whole cohort was [median (range)] 4.6 (-3.8 to 18) ml/min/year. No patient with 185 allele was found. Patients with 179/183 and 179/179 genotype (n = 14), who were considered together and named 179 carriers, had a slower rate of GFR decline [2.1 (0.06-11.7) ml/min/year] as compared to patients with Decorin 183/183 genotype (n = 65) [5.6 (-3.8 to 18) ml/min/year; p < 0.001]. In addition, when considering individual data, patients carrying the 179 allele had a 3.0 (95%CI: 1.8-4.2)-fold higher probability to be slow progressors (i.e. GFR decline below the median). This difference could not be accounted for by differences in duration of disease, type and duration of antihypertensive therapy, albumin excretion rate, blood glucose or blood pressure control. In a multivariate logistic analysis albumin excretion rate (p < 0.001), mean arterial pressure (p = 0.07) and Decorin gene polymorphism (p = 0.036), but not HbA1c, were independently correlated with the rate of dGFR fall. CONCLUSION: The 179 allele variant of the Decorin gene is related to a slower progression of DN in type 1 diabetic patients with albuminuria and receiving antihypertensive therapy.

Adult↗
PubMed2001

Subclinical hypothyroidism in obese patients: relation to resting energy expenditure, serum leptin, body composition, and lipid profile.

OBJECTIVE: To evaluate whether subclinical hypothyroidism (SH) affects resting energy expenditure (REE) as well as body composition, lipid profile, and serum leptin in obese patients. RESEARCH METHODS AND PROCEDURES: A total of 108 obese patients with SH defined as normal free thyroxine levels and thyroid-stimulating hormone (TSH) values of > 4.38 microU/ml (mean +/- 2 SD of the values of our reference group of obese patients with normal thyroid function) were compared with a group of 131 obese patients matched for age, sex, and body mass index (BMI) but with normal TSH levels. We assessed estimated daily caloric intake by 7-day recall, REE by indirect calorimetry, body composition by bioelectrical impedance analysis, serum leptin by radioimmunoassay, and lipid profile (i.e., total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides). RESULTS: All of the variables measured were not different between the euthyroid obese patients and those with SH. In a multiple regression model with REE expressed for kilograms of fat free mass (REE/kgFFM) as a dependent variable and percentage of fat mass, BMI, waist-to-hip ratio, age, TSH, free thyroxine, serum leptin, and caloric intake as independent variables, only percentage of fat mass was significantly correlated with REE/kgFFM in both groups. In the SH group only, BMI, waist-to-hip ratio, age, and TSH were related to REE/kgFFM and explained 69.5% of its variability. After dividing the patients with SH using a cutoff TSH value of 5.7 microU/ml, which represents 3 SD above the mean of TSH levels of the group of obese patients with normal thyroid function, only REE/kgFFM was significantly different and lower in the group of more severely hypothyroid patients. DISCUSSION: In patients with obesity, SH affects energy expenditure only when TSH is clearly above the normal range; it does not change body composition and lipid profile. We suggest that, at least in obese patients, evaluation of TSH levels may be useful to rule out a possible impairment of resting energy expenditure due to a reduced peripheral effect of thyroid hormones.

Basal Metabolism↗
PubMed2001

An aid to the early detection and management of diabetic nephropathy: assessment of a new point of care microalbuminuria system in the diabetic clinic.

AIMS: To compare the performance of the DCA2000 microalbuminuria system for albumin and creatinine concentrations and the albumin:creatinine ratio (ACR) with laboratory measurements in the hospital diabetes clinic and to assess the ease of use and applicability by standard clinic personnel. METHODS: Urine albumin and creatinine concentration and ACR were measured in 154 diabetic patient samples and in 77 normal subjects. Both albumin assays are based on immunoturbidimetry. The DCA2000 system utilizes reagent cartridges processed automatically. RESULTS: Control material within-run precision (coefficient of variation (CV)) for albumin and creatinine ranged up to 7.1% and 3.3% respectively. Between-run CVs ranged from 2.1% to 4.3%. Method comparisons yielded correlation coefficients > 0.99 for albumin, creatinine and ACR, only a small negative bias of 3.2 mg/l for albumin and 0.10 mg/mmol for ACR, no concentration-related bias for ACR and no between-method difference for either albumin (P = 0.195) or ACR (P = 0.341). At a laboratory albumin concentration cut-off of 20 mg/l the sensitivity, specificity, negative and positive predictive values were 92.4% 100% 92.7% and 100%. Normal reference range mean albumin, creatinine and ACR values for the DCA2000 and the laboratory were 7.7 mg/l vs. 9.0 mg/l 13.0 mmol/l vs. 12.6 mmol/l and 0.66 mg/mmol vs. 0.81 mg/mmol respectively. Clinic personnel found that the DCA2000 system was easy to use suited the clinic environment and generated confidence in the results. CONCLUSIONS: This point of care system safely substitutes laboratory-based measurements. Ease of use and low cost make it suitable for screening and monitoring diabetes treatment. It facilitates the use of random urines, and may obviate the need for timed samples. This approach has a clear place in the battle to reduce the diabetic vascular disease burden.

Adolescent↗
PubMed2000

Role of insulin-like growth factor (IGF)-1 in the modulation of renal haemodynamics in Type I diabetic patients.

AIMS/HYPOTHESIS: We investigated in normotensive Type I (insulin-dependent) diabetic patients with normoalbuminuria the role of growth hormone-induced IGF-1 in the modulation of renal haemodynamics. METHODS: We measured glomerular filtration (GFR) and renal plasma flow (RPF) at baseline and at 24 h after injection of different doses of growth hormone (0.1, 0.2, 0.4 U x kg(-1) x body weight(-1) in six patients with normal GFR under a euglycaemic clamp. We also examined a 24 h profile of plasma growth hormone and IGF-1 during usual insulin therapy in two other groups each with seven patients with a lower (from 93 to 114 ml x min(-1) x (1.73 m2)(-1) and higher (from 121 to 146 ml min(-1) x (1.73 m2)(-1) GFR. RESULTS: Plasma growth hormone concentrations peaked 2 h after its injection and plasma concentrations of IGF-1 peaked about 24 h after the growth hormone injection. There was a significant increase in GFR and RPF 24 h after the highest dose of the growth hormone injection (corresponding to the highest IGF-1 concentration), from baseline values of 115 +/- 24 and 536 +/- 141 ml x min(-1) x (1.73 m2)(-1) to 160 +/- 33 and 657 +/- 137 ml x min(-1) x (1.73 m2)(-1), respectively (p < 0.01 for GFR and p < 0.05 for RPF). No differences were observed in the 24 h profile of growth hormone and IGF-1 plasma concentrations between the two groups; growth hormone and IGF-1 concentrations were lower than those obtained after the injection of 0.4 U x kg(-1) x body weight(-1) of growth hormone. CONCLUSION/INTERPRETATION: These results show that pharmacological growth hormone-induced IGF-1 concentrations are required to modify renal haemodynamics in Type I diabetic patients and suggest that, under the "physiological" conditions of diabetes, IGF-1 has no role as a mediator of glomerular hyperfiltration.

Adult↗
PubMed2000

Leptin plasma concentrations are dependent on body fat distribution in obese patients.

AIM: To evaluate whether fat distribution plays a role in determining serum leptin concentrations. PATIENTS AND METHODS: One-hundred and forty-seven obese patients, 77 males and 70 females, aged 45.1 +/- 13.2 y (mean +/- s.d.; range 21-73 y), with body mass index (BMI) ranging from 30 to 55 kg/m2 (mean 42.3 +/- 5.9). Ultrasound assessment of the thickness of subcutaneous and preperitoneal fat was carried out and calculation of their ratio as abdominal fat index (AFI), waist-hip ratio (WHR), body composition by bioelectrical impedance to evaluate the percentage of fat mass (FM%) and total amount of fat (FMKg) were also determined. Plasma leptin was measured by radio immuno assay (RIA). RESULTS: In the whole group of patients, serum leptin concentrations were 37.2 +/- 18.4 ng/ml (range 6-101.3 ng/ml); in spite of BMI values not being significantly different, women had leptin values significantly higher (47.4 +/- 17.4 ng/ml) (P < 0.01) than males (28.1 +/- 15.1 ng/ml), also after correction for fat mass. The mean thickness of abdominal subcutaneous fat was 33.7 +/- 12.9 mm and it was significantly (P < 0.001) higher in female (40.9 +/- 10.6 mm) than in male (27.1 +/- 11.2 mm) patients; preperitoneal thickness was 22.9 +/- 7.1 mm, with significantly (P < 0.05) higher values in males (24.2 +/- 6.8 mm) than in females (21.7 +/- 7.3 mm). Accordingly, AFI (in all patients 0.84 +/- 0.6) was significantly higher in males (1.09 +/- 0.6) than in females (0.56 +/- 0.2). In the overall population, leptin concentrations were directly and significantly related to subcutaneous but not preperitoneal fat; they showed a strong inverse relationship with AFI and WHR. When the results were evaluated dividing the patients according to gender, subcutaneous fat thickness showed a stronger association with leptin levels in males than in females, whereas no association was found with preperitoneal fat thickness. Leptin and AFI values were significantly related only in men. WHR values were not correlated with leptin concentrations in either sex. When fat mass was added to the model, subcutaneous fat thickness, AFI and WHR remained independently associated with leptin concentrations. Age and diabetes did not influence these measures. CONCLUSIONS: Fat distribution contributes to the variability in serum leptin in obese patients. In particular, subcutaneous abdominal fat is a determinant of leptin concentration, also independently of the amount of fat mass, whereas the contribution of preperitoneal visceral fat is not significant.

Abdomen↗
PubMed2000

Defective intracellular antioxidant enzyme production in type 1 diabetic patients with nephropathy.

There is an individual susceptibility to diabetic nephropathy, and oxidative stress is believed to play an important role in the pathogenesis of diabetic complications. Active oxygen species induce antioxidant enzyme expression in tissues, an effect considered to be a defensive mechanism. To test whether altered intracellular antioxidant enzyme production might explain the predisposition to diabetic nephropathy, we studied the effect of long-term (12 weeks) exposure to normal (5 mmol/l) or high (22 mmol/l) glucose concentrations on fibroblast antioxidant enzyme gene expression and protein activity in type 1 diabetic patients with and without nephropathy, nondiabetic nephropathic patients, and nondiabetic control subjects. Under conditions of normal glucose concentration in the culture media, CuZnSuperoxide-dismutase, MnSuperoxide-dismutase, catalase, and glutathione-peroxidase activity and mRNA expression were not different among the four groups. Under high-glucose conditions, CuZnSuperoxide-dismutase mRNA and activity increased similarly in all groups (P < 0.001 vs. basal), whereas MnSuperoxide-dismutase did not change. In contrast, catalase mRNA and activity as well as glutathione-peroxidase mRNA and activity increased in fibroblasts from type 1 diabetic patients without nephropathy (P < 0.001), in fibroblasts from nondiabetic nephropathic patients (P < 0.001), and in fibroblasts from nondiabetic control subjects (P < 0.001), but not in fibroblasts from type 1 diabetic patients with nephropathy. Exposure to high glucose concentrations significantly increased lipid peroxidation in cells, higher levels being found in cells from diabetic patients with nephropathy (P < 0.001). These data, while confirming that exposure to high glucose concentrations induces an antioxidant defense in skin fibroblasts from normal subjects, demonstrate a failure of this defensive mechanism in cells from type 1 diabetic patients with nephropathy, whereas skin fibroblasts from diabetic patients without complications or from nondiabetic nephropathic patients have an intact antioxidant response to glucose-induced oxidative stress.

Adult↗
PubMed2000

A PC-1 amino acid variant (K121Q) is associated with faster progression of renal disease in patients with type 1 diabetes and albuminuria.

Insulin resistance characterizes type 1 diabetes in patients with albuminuria. A PC-1 glycoprotein amino acid variant, K121Q, is associated with insulin resistance. We examined the impact of the PC-1 K121Q variant on the rate of decline of the glomerular filtration rate (GFR) by creatinine clearance derived from the Cockroft-Gault formula in 77 type 1 diabetic patients with albuminuria who were followed for an average of 6.5 years (range 2.5-15). Patients carrying the Q allele (n = 22; 20 with KQ and 2 with QQ genotypes) had a faster GFR decline than those patients with the KK genotype (n = 55) (median 7.2 vs. 3.7 ml x min(-1) x year(-1); range 0.16 to 16.6 vs. -3.8 to 16.0 ml x min(-1) x year(-1); P < 0.001). Significantly more patients carrying the Q allele belonged to the highest tertile of GFR decline (odds ratio = 5.7, 95% CI 4.1-7.2, P = 0.02). Levels of blood pressure, HbA1c, and albuminuria were comparable in the two genotype groups. Albuminuria (P = 0.001), mean blood pressure (P = 0.046), and PC-1 genotype (P = 0.036) independently correlated with GFR decline. Because all patients were receiving antihypertensive treatment, the faster GFR decline in the patients carrying the Q allele could be the result of reduced sensitivity to the renoprotective effect of antihypertensive therapy. PC-1 genotyping identifies type 1 diabetic patients with a faster progression of diabetic nephropathy.

Adult↗
PubMed2000

Mechanical stretch-induced fibronectin and transforming growth factor-beta1 production in human mesangial cells is p38 mitogen-activated protein kinase-dependent.

Hemodynamic abnormalities are important in the pathogenesis of the excess mesangial matrix deposition of diabetic and other glomerulopathies. p38-Mitogen-activated protein (MAP) kinase, an important intracellular signaling molecule, is activated in the glomeruli of diabetic rats. We studied, in human mesangial cells, the effect of stretch on p38 MAP kinase activation and the role of p38 MAP kinase in stretch-induced fibronectin and transforming growth factor-beta1 (TGF-beta1) accumulation. p38 MAP kinase was activated by stretch in a rapid (11-fold increase at 30 min, P < 0.001) and sustained manner (3-fold increase at 33 h, P < 0.001); this activation was mediated by protein kinase C (PKC). Stretch-induced fibronectin and TGF-beta1 protein levels were completely abolished (100% inhibition, P < 0.001; and 92% inhibition, P < 0.01, respectively) by SB203580, a specific p38 MAP kinase inhibitor. At 33 h, TGF-beta1 blockade did not affect stretch-induced fibronectin production, but partially prevented stretch-induced p38 MAP kinase activation (59% inhibition, P < 0.05). TGF-beta1 induced fibronectin accumulation after 72 h of exposure via a p38 MAP kinase-dependent mechanism (30% increase over control, P < 0.01). In human mesangial cells, stretch activates, via a PKC-dependent mechanism, p38 MAP kinase, which independently induces TGF-beta1 and fibronectin. In turn, TGF-beta1 contributes to maintaining late p38 MAP kinase activation, which perpetuates fibronectin accumulation.

Biomechanical Phenomena↗
PubMed2000

Low-dose ramipril reduces microalbuminuria in type 1 diabetic patients without hypertension: results of a randomized controlled trial.

OBJECTIVE: To assess if low (1.25 mg) and/or standard (5 mg) doses of the ACE inhibitor ramipril could prevent progression of microalbuminuria (incipient diabetic nephropathy) in normotensive type 1 diabetic patients. RESEARCH DESIGN AND METHODS: This study, using a multicenter randomized placebo-controlled double-blind parallel group, was conducted over 2 years in 28 outpatient diabetic clinics in the U.K. and Ireland. We screened 334 type 1 diabetic patients with suspected microalbuminuria and normal blood pressure; of these, 140 patients 18-65 years of age with a diagnosis of type 1 diabetes and persistent microalbuminuria, defined as urinary albumin excretion rate (AER) of 20-200 microg/min, were enrolled in the study. RESULTS: The proportion of patients progressing to macroalbuminuria was reduced in the ramipril groups but did not reach statistical significance over 2 years. AER was significantly lower at year 2 in the combined ramipril-treated patients versus placebo (P = 0.013). More patients on ramipril regressed to normoalbuminuria (<20 microg/min), with 11% for 1.25 mg ramipril, 20% for 5 mg ramipril, and 4% for placebo (P = 0.053). Blood pressure was significantly reduced to a similar extent with both 1.25 and 5 mg ramipril. Supine systolic blood pressure increased from 130 to 134 mmHg in the placebo group and fell in the 1.25 mg ramipril group (from 132 to 129 mmHg) and in the 5 mg ramipril group (from 134 to 130 mmHg) (P = 0.003, compared with placebo). No statistically significant changes were observed in glomerular filtration rate (GFR) between the placebo- and ramipril-treated groups during the 2-year period. CONCLUSIONS: Microalbuminuria is reduced significantly by ramipril treatment in type 1 diabetic patients without hypertension. Although the magnitude of the response was greater, there is no significant difference between responses to 1.25 or 5 mg ramipril. Small but highly significant reductions in systolic and mean arterial pressures occur in ramipril-treated patients. GFR is stable at this stage of the evolution of diabetic nephropathy and is unaffected by ramipril treatment for 2 years.

Adolescent↗