Francesca Raffaelli

Reactive oxygen species plasmatic levels in ischemic stroke

Oxidative stress is probably one of the mechanisms involved in neuronal damage induced by ischemia-reperfusion, and the antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress. The aim of this study was to investigate the status of oxidative stress, NO and ONOO− levels in patients with atherothrombotic and lacunar acute ischemic stroke and iNOS, eNOS and nitrotyrosine expression in the same patients. Plasma ONOO− levels were significantly higher in patients than in controls while NO decreases in patients in respect to controls. Densitometric analysis of bands indicated that iNOS and N-Tyr protein levels were significantly higher in patients in respect to controls. This study has highlighted a significant NO decrease in our patients compared with controls and this is most probably due to the increased expression of inducible NO synthase by the effect of thrombotic attack. In fact, the constitutive NO isoforms, which produce small amounts of NO, are beneficial, while activation of the inducible isoform of NO, which produces much more NO, causes injury, being its toxicity greatly enhanced by generation of peroxynitrite. The significant ONOO− increase observed in our patients, compared to controls, is most probably due to reaction of NO with O2·−. These findings suggest that free radical production and oxidative stress in ischemic stroke might have a major role in the pathogenesis of ischemic brain injury. Peroxynitrite might be the main marker of brain damage and neurological impairment in acute ischemic stroke.

Oxidative Stress and Erythrocyte Membrane Alterations in Children with Autism: Correlation with Clinical Features

It has been suggested that oxidative stress may play a role in the pathogenesis of Autism Spectrum Disorders (ASD), but the literature reports somewhat contradictory results. To further investigate the issue, we evaluated a high number of peripheral oxidative stress parameters, and some related issues such as erythrocyte membrane functional features and lipid composition. Twenty-one autistic children (Au) aged 5 to 12 years, were gender and age-matched with 20 typically developing children (TD). Erythrocyte thiobarbituric acid reactive substances, urinary isoprostane and hexanoyl-lysine adduct levels were elevated in Au, thus confirming the occurrence of an imbalance of the redox status of Au, whilst other oxidative stress markers or associated parameters (urinary 8-oxo-dG, plasma radical absorbance capacity and carbonyl groups, erythrocyte superoxide dismutase and catalase activities) were unchanged. A very significant reduction of Na+/K+-ATPase activity (−66%, p<0.0001), a reduction of erythrocyte membrane fluidity and alteration in erythrocyte fatty acid membrane profile (increase in monounsaturated fatty acids, decrease in EPA and DHA-ω3 with a consequent increase in ω6/ω3 ratio) were found in Au compared to TD, without change in membrane sialic acid content. Some Au clinical features appear to be correlated with these findings; in particular, hyperactivity score appears to be related with some parameters of the lipidomic profile and membrane fluidity. Oxidative stress and erythrocyte membrane alterations may play a role in the pathogenesis of ASD and prompt the development of palliative therapeutic protocols. Moreover, the marked decrease in NKA could be potentially utilized as a peripheral biomarker of ASD.

Alzheimer's Disease and Diabetes: New Insights and Unifying Therapies

Several research groups have begun to associate the Alzheimer Disease (AD) to Diabetes Mellitus (DM), obesity and cardiovascular disease. This relationship is so close that some authors have defined Alzheimer Disease as Type 3 Diabetes. Numerous studies have shown that people with type 2 diabetes have twice the incidence of sporadic AD. Insulin deficiency or insulin resistance facilitates cerebral β-amyloidogenesis in murine model of AD, accompanied by a significant elevation in APP (Amyloid Precursor Protein) and BACE1 (β-site APP Cleaving Enzime 1). Similarly, deposits of Aβ produce a loss of neuronal surface insulin receptors and directly interfere with the insulin signaling pathway. Furthermore, as it is well known, these disorders are both associated to an increased cardiovascular risk and an altered cholesterol metabolism, so we have analyzed several therapies which recently have been suggested as a remedy to treat together AD and DM. The aim of the present review is to better understand the strengths and drawbacks of these therapies.

Oxidative stress in ischaemic stroke.

Eur J Clin Invest 2011; 41 (12): 1318–1322

Platelet membrane fluidity and Na+/K+ ATPase activity in acute stroke

Stroke is a consequence of a reduction in cerebral blood flow but the mechanisms involved in the production of ischemic damage are complex and probably not fully known. It is hypothesized that alterations in platelet membrane fluidity are directly related to the severity of the stroke as measured by the National Institute of Health Stroke Scale (NIHSS). Thus, the aim of the present study was to investigate Na+/K+ ATPase activity and platelet membrane fluidity, measured by fluorescent probes TMA-DPH and DPH in patients affected by ischemic stroke and controls in order to identify, if any, chemical-physical and/or functional modifications associated with cerebral ischemic damage. Patients were divided into three groups according to the presence of vascular risk factors (Diabetes Mellitus, Hypertension and Smoking) in order to evaluate the possible influence of each risk factor on the NIHSS score and both Na+/K+ ATPase activity and platelet membrane fluidity. Data showed a significant decrease in both Na+/K+ ATPase activity and platelet fluidity values in patients compared to controls. Moreover, all three groups showed a negative significant correlation between NIHSS and Na+/K+ ATPase activity and a positive significant correlation between NIHSS, TMA-DPH and DPH. In conclusion, the present data point out that alterations in the platelet membranes chemical-physical (decreased fluidity) and functional properties (reduced Na+/K+ ATPase activity) rose proportionally with NIHSS increase. These modifications and their interaction with some vascular risk factors might be involved in the pathogenesis of ischemic damage development.

Effect of consumption of dark chocolate on oxidative stress in lipoproteins and platelets in women and in men.

The goal of this research was to investigate the effects of 3 weeks consumption of 50 g flavonoid-rich dark chocolate on lipoprotein oxidative stress in vitro and in vivo in 25 women compared to 25 men. Levels of thiobarbituric acid-reactive substances, conjugated dienes and hydroperoxide levels in HDL and LDL before and after consumption of dark chocolate were determined. Moreover in platelets of the same subjects NO and peroxynitrite levels were studied. TBARs concentration in womens HDL decreased by 26.7% while in mens HDL 23.4%; lipid hydroperoxides decreased in womens HDL by 62.8% while in mens HDL they decreased by 21.1%. Conjugate diene formation decreased in womens HDL by 55.9%, while in mens HDL it decreased by 49.2%. Moreover TBARs concentration decreased in womens LDL by 26.7% after supplementation and in mens LDL by 21.6%; lipid hydroperoxides decreased in womens LDL by 83.6% while in mens LDL they decreased by 64.7%. Moreover conjugate diene formation decreased in womens LDL by 48.2%, while in mens LDL it decreased by 21.6%. After supplementation peroxynitrite values decreased in women by 24% and in men by 18.6% while NO increased after supplementation by 15.7% compared to basal determination in women, and by 32.2% in men. This study showed that a short-term intake of dark chocolate might improve the lipoprotein profile in healthy humans, more so in women than in men, and this might exert a protective effect on the cardiovascular system.

Role of raloxifene on platelet metabolism and plasma lipids

Background  This study was performed to understand the metabolic effects of raloxifene, a selective oestrogen receptor modulator, on platelets in healthy non‐obese postmenopausal women. The data were compared to untreated subjects.

Leptin and paraoxonase activity in cord blood from obese mothers

Abstract Objective: Obesity and/or psychopathological disorders of parents represent risk factors for childhood obesity. The aim of the study was to investigate the link between obesity in pregnancy and oxidative stress. Methods: Venous blood was collected from 37 women at the eighth month of gestation (19 obese and 28 normal weight). Cord blood was obtained at birth from newborns of obese mothers and controls. Cord blood and maternal blood was used to separate plasma to be used for the evaluation of leptin, oxidized LDL and paraoxonase (PON1) activity. Results: Higher levels of leptin were observed both in maternal blood and cord blood of children of obese women compared to normal-weight women. The data also showed lower levels of PON1 activity in plasma of obese women and in the cord blood of their children. Furthermore, a positive correlation was established between levels of PON1 activity in maternal blood and cord blood, suggesting a relationship between PON1 in maternal plasma and fetal cord blood. Conclusions: Essential obesity in pregnancy is associated with hyperleptinemia. PON1 exerts an antioxidant role; therefore, our results demonstrated that obesity exposes to an increased susceptibility to oxidative damage in both mothers and newborns.

Alterations of platelet biochemical and functional properties in newly diagnosed type 1 diabetes: a role in cardiovascular risk?

The involvement of platelets in the pathogenesis of diabetic vascular complications is supported by several studies. Type 1 diabetic (T1D) platelets show increased adhesiveness and aggregation related to a modification of nitric oxide synthase activity. Moreover, different cell types from diabetic patients showed a decreased membrane Na+/K+‐ATPase activity, which might be involved in diabetic complications. The aim of this study was to investigate whether T1D at onset is able to induce alterations of platelet physicochemical and functional properties and whether these changes are affected by hyperglycaemia.

Nitric oxide and peroxynitrite platelet levels in gestational hypertension and preeclampsia

The aim of the study was to investigate platelet nitric oxide (NO) pathways in women with Gestational Hypertension (GH), Preeclampsia (PE) and Controls. Platelet NOx and peroxynitrite (ONOO−) levels, inducible (iNOS) and endothelial nitric oxide synthase (eNOS) and Nitrotyrosine expression (N-Tyr) in 30 women with GH, 30 with PE and 30 healthy pregnant controls, age, parity and gestational age-matched, were assessed. Platelet NOx and ONOO− levels were significantly higher in GH and PE vs. Controls, with higher levels in GH vs. PE. At the same way, iNOS and N-Tyr were significantly higher in GH and PE vs. Controls, with higher levels in GH vs. PE. Since GH expressed higher amount of NO metabolites and higher activation of iNOS compared to PE, we can hypothesize that the severity of hypertensive pathology is almost not related to only NO metabolism, this research confirmed that GH and PE are associated with marked changes in NO pathways; it is not easy to understand if they could be interpreted as causes or consequence of these pathologic states.