Erythrocyte membrane fluidity in mild cognitive impairment and Alzheimer's disease patients.

Alzheimer's disease (AD) is the most common cause of dementia accounting for 60-70% of all demented cases and one of the leading sources of morbidity and mortality in the aging population. Most of the recent literature regards the relationship between plasma oxidative stress and AD, showing that markers of lipid peroxidation are significantly higher in AD and Mild Cognitive Impairment (MCI) patients with respect to control subjects. The increased generation of reactive oxygen species that occurs in AD may be also responsible for oxidative injury to erythrocyte membranes. Since erythrocyte membrane serves as a variable barrier to oxygen transport, changes in its stability can induce cellular hypoxia and the consequence brain tissue oxygenation. In this study, plasma oxygen radical absorbance capacity (ORAC) and erythrocyte membrane fluidity have been evaluated in control, MCI and AD patients. Moreover erythrocyte membrane acetylcholinesterase (AchE) activity has been measured in control and AD patients. Plasma ORAC significantly decreased in MCI and AD subjects with respect to the controls, while a decrease in erythrocyte membrane fluidity has been observed only in MCI patients. No significant differences were detected in erythrocyte AchE activity between control subjects and AD patients.

Effects of short-term hyperoxia on erythropoietin levels and microcirculation in critically Ill patients: a prospective observational pilot study.

BACKGROUND: The normobaric oxygen paradox states that a short exposure to normobaric hyperoxia followed by rapid return to normoxia creates a condition of 'relative hypoxia' which stimulates erythropoietin (EPO) production. Alterations in glutathione and reactive oxygen species (ROS) may be involved in this process. We tested the effects of short-term hyperoxia on EPO levels and the microcirculation in critically ill patients. METHODS: In this prospective, observational study, 20 hemodynamically stable, mechanically ventilated patients with inspired oxygen concentration (FiO2) ≤0.5 and PaO2/FiO2 ≥ 200 mmHg underwent a 2-hour exposure to hyperoxia (FiO2 1.0). A further 20 patients acted as controls. Serum EPO was measured at baseline, 24 h and 48 h. Serum glutathione (antioxidant) and ROS levels were assessed at baseline (t0), after 2 h of hyperoxia (t1) and 2 h after returning to their baseline FiO2 (t2). The microvascular response to hyperoxia was assessed using sublingual sidestream dark field videomicroscopy and thenar near-infrared spectroscopy with a vascular occlusion test. RESULTS: EPO increased within 48 h in patients exposed to hyperoxia from 16.1 [7.4-20.2] to 22.9 [14.1-37.2] IU/L (p = 0.022). Serum ROS transiently increased at t1, and glutathione increased at t2. Early reductions in microvascular density and perfusion were seen during hyperoxia (perfused small vessel density: 85% [95% confidence interval 79-90] of baseline). The response after 2 h of hyperoxia exposure was heterogeneous. Microvascular perfusion/density normalized upon returning to baseline FiO2. CONCLUSIONS: A two-hour exposure to hyperoxia in critically ill patients was associated with a slight increase in EPO levels within 48 h. Adequately controlled studies are needed to confirm the effect of short-term hyperoxia on erythropoiesis. TRIAL REGISTRATION: ClinicalTrials.gov ( www.clinicaltrials.gov ), NCT02481843 , registered 15th June 2015, retrospectively registered.

Dietary nitrate improves age-related hypertension and metabolic abnormalities in rats via modulation of angiotensin II receptor signaling and inhibition of superoxide generation.

Advanced age is associated with increased risk for cardiovascular disease and type 2 diabetes. A proposed central event is diminished amounts of nitric oxide (NO) due to reduced generation by endothelial NO synthase (eNOS) and increased oxidative stress. In addition, it is widely accepted that increased angiotensin II (ANG II) signaling is also implicated in the pathogenesis of endothelial dysfunction and hypertension by accelerating formation of reactive oxygen species. This study was designed to test the hypothesis that dietary nitrate supplementation could reduce blood pressure and improve glucose tolerance in aged rats, via attenuation of NADPH oxidase activity and ANG II receptor signaling. Dietary nitrate supplementation for two weeks reduced blood pressure (10-15mmHg) and improved glucose clearance in old, but not in young rats. These favorable effects were associated with increased insulin responses, reduced plasma creatinine as well as improved endothelial relaxation to acetylcholine and attenuated contractility to ANG II in resistance arteries. Mechanistically, nitrate reduced NADPH oxidase-mediated oxidative stress in the cardiovascular system and increased cGMP signaling. Finally, nitrate treatment in aged rats normalized the gene expression profile of ANG II receptors (AT1A, AT2, AT1A/AT2 ratio) in the renal and cardiovascular systems without altering plasma levels of renin or ANG II. Our results show that boosting the nitrate-nitrite-NO pathway can partly compensate for age-related disturbances in endogenous NO generation via inhibition of NADPH oxidase and modulation of ANG II receptor expression. These novel findings may have implications for nutrition-based preventive and therapeutic strategies against cardiovascular and metabolic diseases.

Inorganic nitrite attenuates NADPH oxidase-derived superoxide generation in activated macrophages via a nitric oxide-dependent mechanism.

Oxidative stress contributes to the pathogenesis of many disorders, including diabetes and cardiovascular disease. Immune cells are major sources of superoxide (O2(∙-)) as part of the innate host defense system, but exaggerated and sustained O2(∙-) generation may lead to progressive inflammation and organ injuries. Previous studies have proven organ-protective effects of inorganic nitrite, a precursor of nitric oxide (NO), in conditions manifested by oxidative stress and inflammation. However, the mechanisms are still not clear. This study aimed at investigating the potential role of nitrite in modulating NADPH oxidase (NOX) activity in immune cells. Mice peritoneal macrophages or human monocytes were activated by lipopolysaccharide (LPS), with or without coincubation with nitrite. O2(∙-) and peroxynitrite (ONOO(-)) formation were detected by lucigenin-based chemiluminescence and fluorescence techniques, respectively. The intracellular NO production was measured by DAF-FM DA fluorescence. NOX isoforms and inducible NO synthase (iNOS) expression were detected by qPCR. LPS increased both O2(∙-) and ONOO(-) production in macrophages, which was significantly reduced by nitrite (10µmol/L). Mechanistically, the effects of nitrite are (1) linked to increased NO generation, (2) similar to that observed with the NO donor DETA-NONOate, and (3) can be abolished by the NO scavenger carboxy-PTIO or by the xanthine oxidase (XO) inhibitor febuxostat. Nox2 expression was increased in activated macrophages, but was not influenced by nitrite. However, nitrite attenuated LPS-induced upregulation of iNOS expression. Similar to that observed in mice macrophages, nitrite also reduced O2(∙-) generation in LPS-activated human monocytes. In conclusion, XO-mediated reduction of nitrite attenuates NOX activity in activated macrophages, which may modulate the inflammatory response.

Higher Levels of Oxidized Low Density Lipoproteins in Alzheimer's Disease Patients: Roles for Platelet Activating Factor Acetyl Hydrolase and Paraoxonase-1.

Alzheimer's disease (AD) is associated with oxidative damage of low density lipoproteins (ox-LDL). In order to investigate whether higher levels of ox-LDL are related to alterations of the activity of enzymes involved in lipid metabolism, we studied the activity of paraoxonase-1 (PON1) and platelet activating factor acetylhydrolase (PAF-AH) in AD patients and the relationship between biochemical markers and severity of the disease. Levels of ox-LDL, PON1 (paraoxonase, arylesterase, and lactonase activities), and PAF-AH activity were evaluated in plasma from 49 patients affected by AD and from 34 control subjects matched for gender and age. Our results demonstrated alterations in the activities of PON1 and PAF-AH in AD patients compared to controls and showed, for the first time, a relationship between the activities of these enzymes, ox-LDL levels, and severity of the disease. A significant negative correlation was observed between the ratio PON1/PAF-AH and ox-LDL. Whatever the causes that contribute to a systemic oxidative stress in AD, our results have shown that AD patients exhibit higher PAF-AH activity than control subjects and higher ox-LDL. This phenomenon, in combination with diminished PON1 in these patients and, consequently, the relatively lower ratio PON1/PAF-AH activity, could contribute to inflammation and oxidative stress of plasma lipoproteins.

Effects of in vitro supplementation with Syzygium cumini (L.) on platelets from subjects affected by diabetes mellitus.

The aim of this study was to assess the in vitro effects of Syzygium cumini (L.) (Sc) incubation on platelets from patients with diabetes, in order to test its efficacy as a potential adjuvant therapy. This study was performed on 77 patients with diabetes [29 in good (DMgc) and 48 in poor glycemic control (DMpc)] and 85 controls. In patients, platelets were analyzed at recruitment and after in vitro Sc incubation (final concentration of 200 µg/ml for 3 hours at 37 °C), whereas in controls only basal evaluation was performed. Lipoperoxide and nitric oxide (NO) levels, superoxide dismutase (SOD) and Na(+)/K(+) ATPase activities, total antioxidant capacity (TAC), and membrane fluidity tested by anisotropy of fluorescent probes 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 1-6-phenyl-1,3,5-hexatriene (DPH) were determined. Collagen-induced platelet aggregation was also evaluated. In vitro Sc activity counteracts oxidative damage, by improving platelet function through augmented membrane fluidity and Na(+)/K(+) ATPase activity; it also enhances antioxidant system functionality by increasing NO levels, SOD activity, and TAC and by decreasing lipoperoxide levels both in whole samples and in DMgc and DMpc. In addition, a slight tendency towards collagen-induced platelet aggregation decrease after Sc was observed. However, all these parameters, even after improvement, did not reach the levels of control subjects. Our results suggest that Sc may have a preventive and protective effect in oxidative damage progression associated with diabetes mellitus and its complications. If our data will be confirmed, Sc supplementation might become a further tool in the management of this disease, especially in view of its easy availability, safety, low cost, and absence of side effects.

Oxytocin, its antagonist Atosiban, and preterm labor: a role for placental nitric oxide.

OBJECTIVE: The aim of the present study was to understand the role played by Atosiban, an oxytocin receptor antagonist, on trophoblastic human cells, and the molecular bases of its efficacy and safety in the treatment of preterm labor. NO, peroxinitrite production and NOS expression have been evaluated on placenta obtained from term and preterm labors. PATIENTS AND METHODS: We studied trophoblast cells isolated from selected placental tissue from 20 controls and 20 preterm patients after cesarean sections. Each sample was studied at basal state and after 2 hours incubation with oxytocin and Atosiban. RESULTS: Significant variations of NO levels, peroxynitrite production and iNOS and eNOS expression both in the preterm, term samples and in each of the considered groups were observed. In the control group Atosiban re-established NO levels that were reduced after incubation with oxytocin, while in preterm samples NO levels were not only re-established but, after incubation with Atosiban, significantly increased compared to basal levels. CONCLUSIONS: This confirms the beneficial role of Atosiban in prolonging the pregnancy of spontaneous labor at very early gestational periods. In conclusion, Atosiban might be an effective drug to prevent preterm labor, in the therapeutic approach to this pathology.

Interleukin-1ß, cyclooxygenase-2, and hypoxia-inducible factor-1α in asthenozoospermia.

Impaired male fertility may have a variety of causes, among which asthenozoospermia. In its etiology, several bioactive substances, such as cytokines may be involved. In this context, our aim was to evaluate the expression of interleukin-1ß, cyclooxygenase-2, and hypoxia-inducible factor-1α, in spermatozoa isolated from normospermic fertile donors and asthenozoospermic infertile patients. We evaluated twenty-eight infertile patients affected by idiopathic asthenozoospermia and twenty-three normospermic fertile donors, age-matched. Sperm parameters were evaluated; immunohistochemical analysis and enzyme-linked immunosorbent assay were then performed in isolated spermatozoa. Spermatozoa from the asthenozoospermic group presented an increased expression of IL-1ß, COX-2, and HIF-1α compared with the normospermic fertile subjects. Our results can lead us to speculate that the increased expression of these substances may influence sperm motility. Nevertheless, further studies are needed in order to assess whether these bioactive mediators have a potential relevance as targets in future therapeutic strategies for the treatment of male infertility.

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 ß-amyloidogenesis in murine model of AD, accompanied by a significant elevation in APP (Amyloid Precursor Protein) and BACE1 (ß-site APP Cleaving Enzime 1). Similarly, deposits of Aß 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.