Background. Issues regarding cancer stem cell (CSC) movement are important in neurosphere biology as cell-cell or cell-environment interactions may have significant impacts on CSC differentiation and contribute to the heterogeneity of the neurosphere. Aims. Despite the growing body of literature data on the biology of brain tumor stem cells, floating CSC-derived neurospheres have been scarcely characterized from a morphological and ultrastructural point of view. Results. Here we report a morphological and ultrastructural characterization performed by live imaging and scanning electron microscopy. Glioblastoma multiforme (GBM) CSC-derived neurospheres are heterogeneous and are constituted by cells, morphologically different, capable of forming highly dynamic structures. These dynamic structures are regulated by not serendipitous cell-cell interactions, and they synchronously pulsate following a cyclic course made of "fast" and "slow" alternate phases. Autocrine/paracrine non canonical Wnt signalling appears to be correlated with the association status of neurospheres. Conclusions. The results obtained suggest that GBM CSCs can behave both as independents cells and as "social" cells, highly interactive with other members of its species, giving rise to a sort of "multicellular organism".

The goal of the study is to evaluate if the use of rotary nickel-titanium (RNT) instruments, as Hedstroem files, is safe. Twelve twisted files (TF) RNT instruments size 06-25 were selected and randomly divided in 2 groups of 6 instruments each. Group A (new instruments) were used as control. Group B (test) instruments were clinically used only as Hedstroem files in a canal that had been previously instrumented to the working length with other 06-25 RNT instruments. Group B instruments were used only in the straight portion of the canal (1 minute at 1000 rpm). A cyclic fatigue test was performed for each instrument of groups. Data were statistically analyzed (Student's t-test). Results showed no significant difference (P > 0.05) between groups A and B. Data confirmed that the use of TF instruments as Hedstroem files is a safe procedure. Cross section images and volumes of the same instrument, before and after cyclic fatigue testing, have been obtained by means of microtomographic analysis to evaluate possible microstructure alterations.

Scopo dello studio è valutare se l'utilizzo degli strumenti rotanti nichel titanio come Hedstroem file è sicuro. Dodici twisted files (TF), dimensioni 06-25, sono stati selezionati e suddivisi random in 2 gruppi di 6 strumenti ciascuno. Il gruppo A (strumenti nuovi) composto da strumenti utilizzati come controllo. Il gruppo B (test) composto da strumenti utilizzati, clinicamente solo come Hedstroem file in un canale, in precedenza strumentato fino alla lunghezza di lavoro con altri strumenti rotanti 06-25. Gli strumenti del gruppo B sono stati utilizzati soltanto nella porzione rettilinea del canale (1 minuto a 1000 rpm). È stato eseguito un test di fatica ciclica sugli strumenti dei due gruppi. I dati sono stati analizzati statisticamente (Student's t-test). I risultati non mostrano differenze statisticamente significative (P > 0,05) tra i due gruppi. I dati raccolti hanno confermato che l'utilizzo dei TF come Hedstroem file rappresenta una procedura sicura. Tramite analisi microtomografica sono state ottenute delle immagini di sezioni e volumi dello stesso strumento, prima e dopo l'applicazione di fatica ciclica, per valutare eventuali alterazioni microstrutturali.