Nadia Bortolotti

Meal-Generated Oxidative Stress in Type 2 Diabetic Patients

OBJECTIVE Free radical production has been reported to be increased in diabetic patients and to be involved in the pathogenesis of diabetic complications. In this study, a standardized meal was administered to 10 type 2 diabetic patients and 10 healthy matched normal subjects to evaluate its effects on plasma oxidative stress generation. RESEARCH DESIGN AND METHODS In diabetic patients, at baseline and after the meal, plasma malondialdehyde (MDA), vitamin C, protein SH groups, uric acid, vitamin E, and total plasma radical-trapping parameter, which evaluates plasma antioxidant capacity due to known and unknown antioxidants present in the plasma as well as their mutual cooperation, were measured. RESULTS After the meal, plasma MDA and vitamin C increased, while protein SH groups, uric acid, vitamin E, and total plasma radical-trapping parameter decreased more significantly in the diabetic subjects than in control subjects. CONCLUSIONS This finding shows that in the absorptive phase, free radicals are produced in diabetic patients. Since plasma glucose, but not insulin, rose significantly more in diabetic subjects than in control subjects, hyperglycemia may play an important role in the generation of postprandial oxidative stress in diabetic patients.

Meal-induced oxidative stress and low-density lipoprotein oxidation in diabetes: The possible role of hyperglycemia

Oxidative stress and its contribution to low-density lipoprotein (LDL) oxidation have been implicated in the pathogenesis of vascular diabetic complications. However, the relationship between hyperglycemia, hyperinsulinemia, hyperlipidemia, and oxidative stress is still debated. If plasma glucose and/or insulin and/or lipid are some of the most important determinants of oxidative stress in diabetes, then their typical postprandial elevations in diabetes would be expected to favor oxidative stress and LDL oxidation. To test this hypothesis, in type 2 diabetic patients, we evaluated the effects of two different standard meals designed to produce different levels of postprandial hyperglycemia on the plasma oxidative status and LDL oxidation. The meals were administered in randomized order to each of 10 type 2 diabetic patients. Blood samples were collected at baseline and 60 and 120 minutes after the meals. In every sample, plasma levels of glucose, insulin, cholesterol, triglycerides, nonesterified fatty acids (NEFAs), malondialdehyde (MDA), and the total radical-trapping antioxidant parameter (TRAP) were measured. LDL susceptibility to oxidation was evaluated at baseline and after 120 minutes. Plasma glucose, insulin, triglycerides, and MDA increased and NEFAs and TRAP significantly decreased after either meal. The variations in plasma glucose, MDA, and TRAP were significantly greater and LDL was more susceptible to oxidation after the meal that produced a significantly higher degree of hyperglycemia. These results suggest that postprandial hyperglycemia may contribute to oxidative stress in diabetic patients, providing a mechanistic link between hyperglycemia and diabetic vascular disease.

Total Radical-Trapping Antioxidant Parameter in NIDDM Patients

OBJECTIVE The existence of an oxidative stress in diabetes is still debated. This is largely due to the lack of good tools to assay the level of oxidative stress. The use of total radical-trapping antioxidant parameter (TRAP) has recently been proposed to explore the antioxidant property of a plasma sample. TRAP may be either directly measured by a fluorescence-based method (TRAPm) or calculated (TRAPc) by a mathematical formula, taking into account the serum levels of four natural antioxidants: protein-bound SH (thiol) groups, uric acid, vitamin E, and vitamin C. The difference between TRAPm and TRAPc is due to antioxidants, which are still unidentified, and to the possible synergism among the antioxidants. RESEARCH DESIGN AND METHODS In this study, we evaluated malondialdehyde (MDA), TRAPm, TRAPc, protein-bound SH groups, uric acid, vitamin E, and vitamin C in 40 NIDDM patients and 40 matched normal control subjects. RESULTS TRAPm and TRAPc were significantly lower in diabetic patients. A good correlation between TRAPm and TRAPc was found in both NIDDM patients (r = 0.68, P < 0.0001) and control subjects (r = 0.74, P < 0.0001). Protein-bound SH groups and uric acid were significantly lower in diabetic subjects, while MDA and vitamin E level were significantly higher. After correction for serum triglycerides (MDA) and cholesterol (vitamin E), MDA lost significance, while vitamin E did not. Vitamin C was not different in the two groups. CONCLUSIONS These data show decreased TRAP levels in NIDDM patients, suggesting the existence of lower antioxidant defenses in diabetes. The decrease appears to be due to various antioxidants, some of them not yet clearly defined. TRAP may represent a more reliable estimation of serum antioxidant capacity than the measurement of each known antioxidants. The correlation found between TRAPm and TRAPc values suggests that TRAPc, easier to measure than TRAPm, might be adequately reliable for routine assessment of oxidative stress in diabetic patients.

Increased Circulating Intercellular Adhesion Molecule-1 Levels in Type II Diabetic Patients: The Possible Role of Metabolic Control and Oxidative Stress

Blood levels of the circulating form of the integrin intercellular adhesion molecule-1 (ICAM-1), malondialdehyde (MDA), and hemoglobin A1c (HbA1c) were studied at baseline and 3 months after improved metabolic control in 25 type II diabetic patients without signs of macroangiopathy, and were compared with those in 15 matched healthy normal controls. Circulating ICAM-1 and MDA levels were increased in diabetic patients, both at baseline and 3 months later. However, with improving metabolic control HbA1c, circulating ICAM-1, and MDA significantly decreased. A significant correlation between circulating ICAM-1, HbA1c, and MDA was found in diabetic patients at each time. Multiple regression analysis considering circulating ICAM-1 as the dependent variable and HbA1c and MDA as independent variables, showed a significant correlation between the three variable at each time. Similar correlations were found in control subjects. These data show increased levels of circulating ICAM-1 in type II diabetic patients, independent of the presence of macroangiopathy. Moreover, these results suggest that oxidative stress and metabolic control might participate in determining increased circulating ICAM-1 levels in both type II diabetic patients and normal subjects.

Red wine protects diabetic patients from meal-induced oxidative stress and thrombosis activation: a pleasant approach to the prevention of cardiovascular disease in diabetes

Background Oxidative stress and thrombosis have been reported to be increased in diabetic patients and involved in the pathogenesis of cardiovascular complications. It has been demonstrated in diabetic patients that consumption of a meal is accompanied by the generation of an oxidative stress and of a hypercoagulable state. It is well recognized that red wine shows antithrombotic activity and that its ingestion increases plasma antioxidant capacity in man. In this study the possibility that red wine consumption may reduce the oxidative stress and thrombosis produced postprandially in diabetic patients has been evaluated.

Characterization of the binding of Fe(III) to F1ATPase from bovine heart mitochondria

The binding of Fe(III) to F1ATPase purified from beef heart mitochondria has been characterized by chemical analyses and EPR spectroscopy. F1ATPase binds 2 of Fe(III)/mol of protein selectively in the presence of saturating concentrations of ATP. In the absence of nucleotides or in the presence of either saturating ADP or limiting ATP concentrations, the enzyme binds 1 equivalent of Fe(III). F1ATPase pretreated with 5′‐p‐fluorosulfonylbenzoyladenosine, that selectively modifies the noncatalytic sites, binds only 1 mol of Fe(III)/mol of protein in the presence of either saturating ATP or ADP. Fe(III)‐loaded F1ATPase containing either 1 or 2 equivalents of Fe(III) show identical EPR signals at g = 4.3. The signals are not perturbed by the binding of nucleotides to the enzyme while they are altered by phosphate addition. These results indicate that F1ATPase contains two distinct Fe(III)‐binding sites, which differ from nucleotide‐binding sites, and that one of these sites is opened up for Fe(III) uptake by conformational changes induced by binding of ATP to the loose non‐catalytic site.

Analysis of the conformation and stability of rat TTF‐1 homeodomain by circular dichroism

The conformational stability of TTF‐1HD has been determined by CD‐monitored thermal denaturation and isothermal urea unfolding studies. The Gibbs free energy of stabilization found are 1.44 and 1.26 kcal·mol−1, respectively. TTF‐1HD exhibits a T m of 42°C and a δC p of 80 cal·mol−1·K−1 indicating that TTF‐1HD, when free in solution, is a mobile flexible segment folded into loose helices. Such a flexibility would be relevant for the DNA‐binding function of this homeodomain. In fact, a small reduction of the α‐helical content of TTF‐1HD significally modifies its DNA‐binding activity.

Circulating standard CD44 isoform in patients with liver disease: relationship with other soluble adhesion molecules and evaluation of diagnostic usefulness.

OBJECTIVES To verify the diagnostic usefulness of soluble CD44 (sCD44) in liver diseases. METHODS We studied 142 subjects (90 male, 52 female): 14 had acute hepatitis (AH); 45, noncirrhotic chronic liver disease (CLD); 34, cirrhosis; 35 had extrahepatic diseases (EHD); and 14 were healthy controls. sCD44, soluble intercellular adhesion molecule-1 (slCAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured immunoenzymatically. RESULTS Patients with AH or cirrhosis had higher sCD44 in comparison to CLD, EHD, and controls (p < 0.01). On univariate analysis, sCD44 was associated with sVCAM-1, sICAM-1, bilirubin, cholinesterase, aspartate aminotransferase, and alkaline phosphatase (p < 0.001). By stepwise discriminant analysis, a set of variables, including sCD44 and sVCAM-1, were entered into a model that allocated correctly 79% of observations (p < 0.0001). However, when adhesion molecules were excluded, the model could still allocate correctly 72% of observations. CONCLUSION Although sCD44 concentration increases during severe acute or chronic liver disease, its measurement adds little to the clinical information provided by traditional liver biochemistry.

Ischemia-modified albumin in pregnancy.

OBJECTIVE In normal pregnancies, a hypoxic intrauterine environment seems necessary for early trophoblast development. In this context, maternal serum levels of ischemia-modified albumin (IMA) are elevated, reflecting the oxidative stress associated with placental development. The aim of this study was to evaluate IMA and pregnancy-associated plasma protein A (PAPP-A) in mothers bearing small-for-gestational-age (SGA) fetuses compared to normal pregnancies. STUDY DESIGN A prospective study was performed between June 2010 and June 2011. Serum total albumin, IMA and PAPP-A concentrations were determined in 81 pregnant women in three different periods: 1st trimester, 2nd trimester and postpartum. Two groups of subjects were retrospectively identified: Group (1) mothers bearing appropriate-for-gestational-age (AGA) fetuses, and Group (2) mothers bearing SGA fetuses. Serum total albumin and IMA concentrations were determined in 198 non-pregnant women as controls. RESULTS Serum IMA concentrations increase during gestation. IMA/albumin serum levels in the 1st trimester were significantly higher in subjects of Group (2) (p<0.05), whereas values of serum PAPP-A MoM were significantly lower (p<0.05). CONCLUSIONS Elevated IMA serum levels together with low levels of PAPP-A were detected in the 1st trimester in mothers bearing SGA fetuses, and this may reflect early placental changes occurring before clinical manifestation of SGA.

Value of serum C-reactive protein measurement in the detection of hepatocellular carcinoma superimposed on liver cirrhosis

We investigated whether, in Italian patients, C-reactive protein (CRP) determination could be considered a useful adjunct, complementary to α1-fetoprotein, in the detection of liver cancer. CRP was determined by particle-enhanced nephelometry in 171 subjects (102 male, 69 female). Fifty-five patients had mild chronic liver disease (CLD), 45 cirrhosis (CIR), 38 hepatocellular carcinoma (HCC); 33 subjects were healthy controls. Patients with HCC and CIR had higher CRP levels (P<0.05) than those found in patients with CLD and controls. CRP higher than 5 mg/l was found in 30/38 (78.9%) patients with HCC, 28/45 (62.2%) patients with CIR, 16/55 (29.1%) patients with CLD (χ2 56.0,P<0.0001). Sensitivity, specificity and diagnostic accuracy of CRP in diagnosing HCC with respect to CLD+CIR were: 78.9%, 56.0% and 34.9%. However, when considered only in the subgroup of patients with α1-fetoprotein below or equalling 30 ng/ml, they were 50.0%, 54.3% and 4.3% respectively. In conclusion, CRP concentration is frequently elevated in patients with HCC, however, it does not seem to improve the ability of α1-fetoprotein to discriminate HCC from CIR.