Extracellular Vesicles: Messengers of p53 in Tumor–Stroma Communication and Cancer Metastasis

Tumor progression to a metastatic and ultimately lethal stage relies on a tumor-supporting microenvironment that is generated by reciprocal communication between tumor and stromal host cells. The tumor–stroma crosstalk is instructed by the genetic alterations of the tumor cells—the most frequent being mutations in the gene Tumor protein p53 (TP53) that are clinically correlated with metastasis, drug resistance and poor patient survival. The crucial mediators of tumor–stroma communication are tumor-derived extracellular vesicles (EVs), in particular exosomes, which operate both locally within the primary tumor and in distant organs, at pre-metastatic niches as the future sites of metastasis. Here, we review how wild-type and mutant p53 proteins control the secretion, size, and especially the RNA and protein cargo of tumor-derived EVs. We highlight how EVs extend the cell-autonomous tumor suppressive activity of wild-type p53 into the tumor microenvironment (TME), and how mutant p53 proteins switch EVs into oncogenic messengers that reprogram tumor–host communication within the entire organism so as to promote metastatic tumor cell dissemination.     

Semi‐Markovian modelling and performance analysis of variable rate traffic in ATM networks

Semi‐Markovian processes (SMP) serve as a versatile means to model various traffic types generated by sources or superposed from links in ATM networks. An efficient discrete time analysis method is proposed for SMP/G/1 queueing systems to evaluate ATM switches with non‐renewal input. Some basic results are derived for the autocorrelation function of semi‐Markovian processes and for the effect of state space reduction on autocorrelation, which show how to represent correlated traffic with given characteristic by an adequate SMP model of limited size. This revised version was published online in June 2006 with corrections to the Cover Date.     

IV-Controlling in einem Systemhaus

This paper analyses the characteristics of software houses as service providers. The tasks of internal IT-services are determined from these characteristics and a reporting system for the IT-controlling is outlined. The concept results from the analysis of one of the 25 largest German software houses. The paper concludes with a case study of the fiscal year 2000 IT-controlling report of the above-mentioned firm.     

Graphite formation on Ni film by chemical vapor deposition

Thin film formation of graphite by chemical vapor deposition using 2-methyl-1,2′-naphthyl ketone as a starting material was carried out on Ni film substrates. On Ni films directly deposited on quartz glass, the graphite films were obtained when the Ni film thickness was above 1 000 Å and above 5 000 Å at 700 °C and 1 000 °C, respectively. Depositions on thinner Ni film substrates comprise amorphous carbon (a-C) or graphite tubes which was owing to the thermal coagulation of the Ni film into droplets. On the other hand, graphite film was obtained on the Ni film with thickness 10 Å when a-C was inserted between the Ni film and the quartz glass. The coagulation of the Ni film is considered to be avoided by inserting a-C layer.     

Positive interpolation with rational quadratic splines

A necessary and sufficient criterion is presented under which the property of positivity carry over from the data set to rational quadratic spline interpolants. The criterion can always be satisfied if the occuring parameters are properly chosen.