Stefano Marini

Aβ(31–35) and Aβ(25–35) fragments of amyloid beta-protein induce cellular death through apoptotic signals: Role of the redox state of methionine-35

Taken together our result indicate that Aβ(31–35) and Aβ(25–35) peptides in non‐aggregated form, i.e., predominantly monomeric, are strongly neurotoxic, having the ability to enter within the cells, determining mitochondrial damage with an evident trigger of apoptotic signals. Such a mechanism of toxicity seems to be dependent by the redox state of methionine‐35.

Aβ(31–35) peptide induce apoptosis in PC 12 cells: Contrast with Aβ(25–35) peptide and examination of underlying mechanisms

Abstract The toxic behaviour of the two shorter sequences of the native Aβ amyloid peptide required for cytotoxicity i.e., Aβ(31–35) and Aβ(25–35) peptides, was studied. We have shown that Aβ(31–35) peptide induces neurotoxicity in undifferentiated PC 12 cell via an apoptotic cell death pathway, including caspase activation and DNA fragmentation. Aβ(25–35) peptide, like the shorter amyloid peptide has the ability to induce neurotoxicity, as evaluated by the MTS reduction assay and by adherent cell count, but the Aβ(25–35) peptide-induced neurotoxicity is not associated with any biochemical features of apoptosis. The differences observed between the neurotoxic properties of Aβ(31–35) and Aβ(25–35) peptides might result on their different ability to be internalised within the neuronal cells. Furthermore, this study reveals that the redox state of methionine residue, C-terminal in Aβ(31–35) and Aβ(25–35) peptides affect in a different way the toxic behaviour of these two short amyloid fragments. Taken together our results suggest that Aβ(31–35) peptide induces cell death by apoptosis, unlike the Aβ(25–35) peptide and that role played by methionine-35 in Aβ induced neurotoxicity might be related to the Aβ aggregation state.

In vivo cocaine administration influences lymphokine production and humoral immune response

SummaryThe effect of in vivo cocaine administration on in vitro mitogen-induced lymphokine production was examined. Splenocyte cultures from BALB/c mice treated with an acute (1 mg/kg) or daily cocaine administration (1 mg/kg/day for 7 consecutive days) were less responsive to induction of IFN-γ, IL-2 and IL-4 production by mitogen stimuli. We also evaluated the humoral immune response to both a T-dependent (HEL) and a T-independent antigen (rHBcAg). It was found that cocaine inhibits T-dependent antibody production only. This inhibition was greatest when cocaine was given during immunization. The results suggest that T-cell-mediated responses may be more affected by cocaine use/abuse.

Studies on the chemistry of pyrimidine derivatives with dimethyldioxirane: synthesis, cytotoxic effect and antiviral activity of new 5,6-oxiranyl-5,6-dihydro and 5-hydroxy-5,6-dihydro-6-substituted uracil derivatives and pyrimidine nucleosides

Abstract The oxidation of uracil derivatives and pyrimidine nucleosides performed in CH2Cl2 with dimethyldioxirane afforded new 5,6-oxiranyl-5,6-dihydro and cis -/ trans -5,6-dihvdroxv-5,6-dihydro-derivatives. When the oxidations were performed in the presence of methanol as nucleophile cis - and trans - 5-hydroxy-6-methoxy-5,6-dihydro derivatives were obtained in acceptable yields. Cis - and trans -1,3- dimethyl-5-hydroxy-6-alkylamino-5,6-dihydro uracils were obtained by nucleophilic ring opening of the 1,3-dimethyl-5,6-oxiranyl-5,6-dihydro uracil in the purified form. Interestingly some of the new title products revealed low cytotoxicity and selective antiviral activity against DNA and RNA Viruses. In particular, compound 17b shows a strong and selective inhibition of the Sendai virus with lower effect on Herpes Simplex-1 virus. Compound 17b is also able to slightly inhibit HIV-1 virus at high concentrations, but in this case a cytotoxic effect was observed.

Thymosin alpha one restores murine T-cell-mediated responses inhibited by In vivo cocaine administration

The effects of different in vivo thymosin alpha one (T alpha 1) treatments on T-cell responses inhibited by cocaine abuse were studied. Administration during cocaine treatment promoted a faster recovery of normal natural killer (NK) cell activity after the suspension of abuse. Suspension of cocaine plus repeated T alpha 1 administrations strongly restored NK activity and, interestingly, spleen cells from mice treated with T alpha 1 during and after cocaine administration achieved a very rapid recovery and the greatest stimulation of natural cytotoxicity. This last treatment also restored the cocaine-inhibited specific T-cell response (i.e. allogeneic cytotoxic T-lymphocyte (CTL) generation) and abrogated the cocaine-induced suppression of interferon gamma (IFN-gamma), interleukin 2 (IL-2) and IL-4 production. Finally restoration and induction of thymic cellularity were significant when T alpha 1 was given during and after cocaine administration. The present investigation provides evidence for the first time that thymic hormones could be of potential value in controlling cocaine-induced impairment of T-cell-mediated immunity in the mouse.

A potent and selective inhibition of parainfluenza 1 (Sendai) virus by new 6-oxiranyl-, 6-methyloxiranyluracils, and 4(3H)-pyrimidinone derivatives

Several new 6-oxiranyl-, 6-methyloxiranyluracils, and pyrimidinone derivatives, synthesized by the lithiation-alkylation sequence of 1,3,6-trimethyluracil, 1,3-dimethyl-6-chloromethyluracil, and 2-alkoxy-6-methyl-4(3H)-pyrimidinones, showed a potent and selective antiviral activity against the parainfluenza 1(Sendai) virus replication.

Proteasome Activity Is Affected by Fluctuations in Insulin-Degrading Enzyme Distribution

Insulin-Degrading-Enzyme (IDE) is a Zn2+-dependent peptidase highly conserved throughout evolution and ubiquitously distributed in mammalian tissues wherein it displays a prevalent cytosolic localization. We have recently demonstrated a novel Heat Shock Protein-like behaviour of IDE and its association with the 26S proteasome. In the present study, we examine the mechanistic and molecular features of IDE-26S proteasome interaction in a cell experimental model, extending the investigation also to the effect of IDE on the enzymatic activities of the 26S proteasome. Further, kinetic investigations indicate that the 26S proteasome activity undergoes a functional modulation by IDE through an extra-catalytic mechanism. The IDE-26S proteasome interaction was analyzed during the Heat Shock Response and we report novel findings on IDE intracellular distribution that might be of critical relevance for cell metabolism.

Synthesis, Cytotoxic Effect and Antiviral Activity of 1-(β-D-Arabinofuranosyl)-5-Bromo-N4-Substitutedcytosine and 1-(β-D-Arabinofuranosyl)-5-Bromo-4-Methoxypyrimidin-2(1h)-One Derivatives

A convenient and mild synthesis of 5-bromo-N4-substituted-1-(beta-D-arabinofuranosyl)cytosine and 5-bromo-O4-methyl-1-(beta-D-arabinofuranosyl)pyrimidin-2(1H)-one derivatives by selective oxyfunctionalization of the corresponding 4-thionucleosides with 3,3-dimethyldioxirane is reported. The cytotoxicity and the antiviral activity against parainfluenza 1 (Sendai virus) of all new synthesized products are also reported.

Retention of Mitochondria in Mature Human Red Blood Cells as the Result of Autophagy Impairment in Rett Syndrome

Rett Syndrome (RTT), which affects approximately 1:10.000 live births, is a X-linked pervasive neuro-developmental disorder which is caused, in the vast majority of cases, by a sporadic mutation in the Methyl-CpG-binding protein-2 (MeCP2) gene. This is a transcriptional activator/repressor with presumed pleiotropic activities. The broad tissue expression of MeCP2 suggests that it may be involved in several metabolic pathways, but the molecular mechanisms which provoke the onset and progression of the syndrome are largely unknown. In this paper, we report that primary fibroblasts that have been isolated from RTT patients display a defective formation of autophagosomes under conditions of nutrient starvation and that the mature Red Blood Cells of some RTT patients retain mitochondria. Moreover, we provide evidence regarding the accumulation of the p62/SQSTM1 protein and ubiquitin-aggregated structures in the cerebellum of Mecp2 knockout mouse model (Mecp2−/y) during transition from the non-symptomatic to the symptomatic stage of the disease. Hence, we propose that a defective autophagy could be involved in the RTT clinical phenotype, which introduces new molecular perspectives in the pathogenesis of the syndrome.

Production and characterization of monoclonal antibodies against l-carnitine: radioimmunologic assays for l-carnitine determination

Monoclonal antibodies against L-carnitine have been produced and characterized. These antibodies have been found to specifically bind L-carnitine and, with different affinities, other carnitine-related compounds. No binding was observed with choline or acetylcholine. These antibodies have been used to measure L-carnitine in biological samples and serum. Data obtained demonstrate that, in biological samples, by using radiolabelled carnitine, it is possible quickly to detect small amounts of carnitine. The high specificity of the test is clearly demonstrated.