Sodium Selenide Toxicity Is Mediated by O2-Dependent DNA Breaks

Hydrogen selenide is a recurrent metabolite of selenium compounds. However, few experiments studied the direct link between this toxic agent and cell death. To address this question, we first screened a systematic collection of Saccharomyces cerevisiae haploid knockout strains for sensitivity to sodium selenide, a donor for hydrogen selenide (H2Se/HSe−/Se2−). Among the genes whose deletion caused hypresensitivity, homologous recombination and DNA damage checkpoint genes were over-represented, suggesting that DNA double-strand breaks are a dominant cause of hydrogen selenide toxicity. Consistent with this hypothesis, treatment of S. cerevisiae cells with sodium selenide triggered G2/M checkpoint activation and induced in vivo chromosome fragmentation. In vitro, sodium selenide directly induced DNA phosphodiester-bond breaks via an O2-dependent reaction. The reaction was inhibited by mannitol, a hydroxyl radical quencher, but not by superoxide dismutase or catalase, strongly suggesting the involvement of hydroxyl radicals and ruling out participations of superoxide anions or hydrogen peroxide. The •OH signature could indeed be detected by electron spin resonance upon exposure of a solution of sodium selenide to O2. Finally we showed that, in vivo, toxicity strictly depended on the presence of O2. Therefore, by combining genome-wide and biochemical approaches, we demonstrated that, in yeast cells, hydrogen selenide induces toxic DNA breaks through an O2-dependent radical-based mechanism

Indagine sulla migrazione sud-nord del bambino malato.

Objective of the multicentric study was to analyze the motivations and the clinical problems related to the intensive migration of sick children from the regions of souther Italy towards pediatric hospitals in the northern regions. From june to december 1982 all children admitted to 10 main pediatric centers of the norther region, coming directly from the souther regions, were contacted and precoded form filled with parents and the attending physician. Official statistics from the northern regions suggest that at least 25,000 sick children, coming from the South, are admitted every years to the northern region pediatric wards. The highest migration is actually from Calabria and Sicily. The vast majority (51%) of them are not referred by hospitals of physicians, and come, with no documents, spontaneously. About half of them refer that they lost confidence with pediatric care in the South, had negative experience, though that in their region there were no well equipped center for their problem. The last was referred also for minor ailmets, which may have not required an hospital admission. 63% of the cases went North because of previous arrengements for follow up in definite centers, at dismission from the northern hospital 78% received a program to come back there for follow up. The diagnosis was already known before admission to North in 65% of cases, also in cases of uncommon diseases. Among the clinical problems mental retardation and convulsions had the highest prevalence, followed by neoplasms, leukemia and kidney pathology. About 40% of them were found affected by minor ailments

La valutazione dei servizi e dei programmi di abilitazione psicoeducativa per bambini e adolescenti autistici

Il lavoro riporta i principali risultati di una indagine sperimentale alla quale hanno partecipato, come unit\ue0 operative, sei regioni italiane ed alcuni istituti clinici e di ricerca. Lo studio si \ue8 indirizzato a indagare il delicato aspetto dei servizi per bambini e adolescenti affetti da autismo, cercando di mettere in evidenza le modalit\ue0 di intervento adottate in vari contesti nazionali, l'efficacia degli stessi, l'apprezzamento da parte delle famiglie, il delicato rapporto costo-efficacia degli interventi. Molto significativa ai fini della ricerca \ue8 risultato anche il contributo fornito dell'associazione delle famiglie di soggetti con autismo (ANGSA)