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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 national programme for paediatric transplants currently implemented at the Istituto Superiore di Sanità is one of the first results of the efforts devoted to the definition of an efficient co-ordination policy of the transplantation activity in Italy. Since 1997 the programme has allowed all transplant centres throughout Italy to share unified waiting lists for kidney, heart, lung and liver, which gives paediatric patients a much better possibility than with local waiting lists. We present the regulations, criteria and operative solutions adopted to make the programme work, and the analysis of the data collected in these three years. The analysis gives statistical information on the composition and evolution of waiting lists and transplants done, which may be useful in the continuous process of revision and improvement of the criteria for recipient selection.

To plan health services it is essential to gauge the needs. In transplant field in Italy, the first suitable data for waiting lists were collected in 1998. The data collected by Istituto Superiore di Sanità gave us a shot of patients field in waiting list at that time. We here analyse more significant data about heart, liver and kidney waiting lists. The situation is very different among north, centre and south of Italy: in South, where transplant activity is low, we found rare transplant centres, and most of patients prefer north centres. In kidney waiting list we found 1100 patients living in southern regions but registered in the waiting list of a different region. These data can help in planning development lines in Italy.

The thesis of this study is that the use of discrete simulations is the most appropriate instrument to support the definition of a kidney allocation procedure. We first furnished a general description of what it means to run a simulation to solve the problems related to the study of the statistical characteristics of any population. In the second part of the paper we mathematically formalized the subject of our study: the statistical properties of waiting lists, allocation algorithm and transplants. The third part reported the results of several simulations we have done with the aim to show the potential of these methods at assessing the most appropriate adjustments for the optimization of any allocation scheme.