Biomedical subjects

L Nanetti

Publications and source records attributed to L Nanetti.

At least 19 recordsLinked to original sources

PubMed2004

LDL and HDL affect nitric oxide metabolism in human astrocytoma cells.

Astrocytes provide structural, trophic and metabolic support to neurons and modulate synaptic activity. Under physiological conditions, neuronal-derived nitric oxide (NO) plays an important role in the modulation of a variety of central nervous system (CNS) functions. NO, although short lived, can travel sufficient distances to be able to act as an intercellular messenger in the brain. Its targets include adjacent neurons and astrocytes. The aim of the present study was performed in order to investigate the effects produced by incubation of lipoproteins, at different times, with human astrocytoma cells and thus measuring NO and its metabolite production. NO and peroxynitrite production, iNOS and nNOS expression by Western immunoblot were evaluated. The LDL and HDL-treated cells showed an increased production of NO, more evident after 12 h, compared to basal levels; concerning peroxynitrite production, LDL and HDL-treated cells showed a higher fluorescence, more evident at 3 h. nNOS and iNOS protein levels were significantly higher in the cells incubated with control LDL and HDL. The present work supports the hypothesis that lipoproteins can induce the formation of reactive astrocytes, inducing iNOS as reported by other authors, giving experimental support to a role played by LDL and HDL inducing a reactive response.

Aged↗

PubMed2004

Gestational diabetes affects platelet behaviour through modified oxidative radical metabolism.

AIMS: Patients with Type 1 and Type 2 diabetes mellitus show altered platelet function including decreased nitric oxide synthase (NOS) activity and increased peroxynitrite production. Gestational diabetes mellitus (GDM) is a clinical condition which is ideal for evaluating short-term effects of impaired glucose metabolism, ruling out the possibility that the platelet abnormalities are a consequence of diabetic complications. The aim of the present work was to study NO metabolism in platelets from pregnant women with GDM. The production of peroxides was also studied as it is strongly involved in peroxynitrite formation. METHODS: Platelet NOS activity and peroxynitrite production, levels of hydroperoxides and thiobarbituric acid reactive substances (TBARS) in platelet membranes in the basal state and after in vitro peroxidative stress with phenylhydrazine were determined in 40 pregnant women with GDM, 40 healthy pregnant women (pregnant controls) of comparable age and gestational age, and 15 healthy non-pregnant women (controls). RESULTS: NOS activity was significantly increased in both groups of pregnant women compared with non-pregnant ones, and in GDM women compared with pregnant controls. Production of peroxynitrite was higher in GDM women than in pregnant controls, who also had significantly reduced production compared with non-pregnant women. Basal levels of peroxidation of the platelet membranes evaluated either by hydroperoxide content and TBARS levels or the susceptibility to peroxidation were increased in GDM patients in comparison with both control groups. CONCLUSIONS: We have shown a modification in platelet NO and peroxynitrite production and an increase in platelet indicators of oxidative stress in GDM women compared with healthy pregnant women which might be at the basis of a cellular dysfunction.

Adult↗

PubMed2004

Modification induced by homocysteine and low-density lipoprotein on human aortic endothelial cells: an in vitro study.

The aim of the present study was to investigate the effect exerted by low-density lipoprotein (LDL) modified by homocysteine (Hcy)-thiolactone (Hcy-LDL) on functional properties on human endothelial cells. Hcy-thiolactone, a reactive product formed in human cells from enzymatic conversion of Hcy, was hypothesized to play an important role in Hcy-induced vascular damages. Using endothelial cultured cells [human aortic endothelial cells (HAEC)] as cellular model, we evaluated nitric oxide (NO) production, cytoplasmic Ca(2+) levels, Na(+)/K(+)-ATPase activity, and peroxynitrite production in cells incubated in the presence of control LDL or Hcy-LDL. Homocysteinylation of LDL was carried out by incubation of LDL, isolated from plasma of healthy subjects, with 100 microm Hcy-thiolactone. A significant increase in cytoplasmic Ca(2+) levels and peroxynitrite production and a decrease in Na(+)/K(+)-ATPase and NO production in HAEC incubated with Hcy-LDL compared with HAEC incubated with control LDL were observed. Moreover, a positive correlation was found between Na(+)/K(+)-ATPase activity and cytoplasmic Ca(2+) content and between peroxynitrite activity and cytoplasmic Ca(2+) content. In conclusion, our results demonstrated that LDL homocysteinylated in vitro induced alterations of functional properties and NO metabolism of human endothelial cells.

Adult↗

PubMed2003

Audiovisual mirror neurons and action recognition.

Many object-related actions can be recognized both by their sound and by their vision. Here we describe a population of neurons in the ventral premotor cortex of the monkey that discharge both when the animal performs a specific action and when it hears or sees the same action performed by another individual. These 'audiovisual mirror neurons' therefore represent actions independently of whether these actions are performed, heard or seen. The magnitude of auditory and visual responses did not differ significantly in half the neurons. A neurometric analysis revealed that based on the response of these neurons, two actions could be discriminated with 97% accuracy.

Acoustic Stimulation↗

PubMed2002

Reduced susceptibility to peroxidation of erythrocyte plasma membranes from centenarians.

The plasma membrane composition affects intracellular processes and the cellular susceptibility to free radical attack, which has been associated with the impairment of cellular functions occurring during senescence. The study of the modifications of the plasma membrane in centenarians might elucidate the biological mechanisms at the basis of longevity and successful aging. The work was performed in 190 subjects, divided into five groups according to the age range: (1) 21-40 years (n=25); (2) 41-60 years (n=30); (3) 61-80 years (n=30); (4) 81-99 years (n=50); and (5) centenarians (> or = 100 years) (n=55). The following determinations were performed on erythrocyte membranes: (i) the lipid peroxide level (Lp) evaluated as malondialdehyde content; (ii) susceptibility to in vitro oxidation evaluated as difference in the content of thiobarbituric acid-reactive substances before and after phenylhydrazine addition; (iii) unsaturated/saturated fatty acid ratio and individual polyunsaturated fatty acid composition measured by gas chromatography; and (iv) fluidity studied by means of the anisotropy of the probe 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). Erythrocyte membranes from centenarians showed: (i) decreased basal lipid peroxide levels and reduced susceptibility to peroxidation in comparison with elderly subjects; (ii) increased unsaturated/saturated fatty acid ratio in comparison with every other age group; (iii) higher levels of eicosapentaenoic and docosahexaenoic acid and reduced content of linoleic and arachidonic acid in comparison with elderly subjects; and (iv) decreased anisotropy of TMA-DPH, i.e. higher fluidity compared with all the other age groups. In conclusion, the present work demonstrates that erythrocyte membranes from centenarians show some distinct features in comparison with elderly subjects that might act in a protective way against injuries.

Adult↗

PubMed2002

Sialic acid content in erythrocyte membranes from pregnant women affected by gestational diabetes.

Sialic acid (SA) content, membrane fluidity, and Na(+)/K(+)-adenosine triphosphatase (ATPase) activity were determined in erythrocyte membrane from 10 nonpregnant women (HNPW), 16 pregnant women affected by gestational diabetes mellitus (GDM), and 25 healthy pregnant women (HPW). In GDM patients the membrane erythrocyte SA content was significantly increased compared with HNPW and membrane fluidity was significantly increased in comparison with HPW. Erythrocyte membrane Na(+)/K(+)-ATPase activity was significantly reduced in GDM patients compared both to HNPW and to HPW subjects. A significant inverse correlation was found between 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) anisotropy and erythrocyte membrane SA content in HNPW and in HPW, while this significant correlation was not observed in GDM. The present results indicate that in comparison with normal pregnancy GDM is characterized by deep alterations of the erythrocyte plasma membrane physicochemical properties (increased fluidity) and functional activities (reduced Na(+)/K(+)-ATPase activity). These modifications might be at the basis of the altered blood viscosity and placental perfusion observed under such conditions. Moreover, these results show that in physiological pregnancy and in the nonpregnant state, the erythrocyte surface membrane fluidity is inversely correlated with SA content, while in GDM there is an unbalance of this relation, which might be associated with the microcirculatory abnormality present in this disease.

Adult↗

PubMed1979