Expression of phosphorylated eIF4E-binding protein 1, but not of eIF4E itself, predicts survival in male breast cancer

Background: Male breast cancer is rare and treatment is based on data from females. High expression/activity of eukaryotic initiation factor 4E (eIF4E) denotes a poor prognosis in female breast cancer, and the eIF4E pathway has been targeted therapeutically. eIF4E activity in female breast cancer is deregulated by eIF4E over-expression and by phosphorylation of its binding protein, 4E-BP1, which relieves inhibitory association between eIF4E and 4E-BP1. The relevance of the eIF4E pathway in male breast cancer is unknown. Methods: We have assessed expression levels of eIF4E, 4E-BP1, 4E-BP2 and phosphorylated 4E-BP1 (p4E-BP1) using immunohistochemistry in a large cohort of male breast cancers (n=337) and have examined correlations with prognostic factors and survival. Results: Neither eIF4E expression or estimated eIF4E activity were associated with prognosis. However, a highly significant correlation was found between p4E-BP1 expression and disease-free survival, linking any detectable p4E-BP1 with poor survival (univariate log rank p=0.001; multivariate HR 8.8, p=0.0001). Conclusions: Our data provide no support for direct therapeutic targeting of eIF4E in male breast cancer, unlike in females. However, as p4E-BP1 gives powerful prognostic insights that are unrelated to eIF4E function, p4E-BP1 may identify male breast cancers potentially suitable for therapies directed at the upstream kinase, mTOR

A CLASP-modulated cell edge barrier mechanism drives cell-wide cortical microtubule organization in Arabidopsis

It is well known that the parallel order of microtubules in the plant cell cortex defines the direction of cell expansion, yet it remains unclear how microtubule orientation is controlled, especially on a cell-wide basis. Here we show through 4D imaging and computational modelling that plant cell polyhedral geometry provides spatial input that determines array orientation and heterogeneity. Microtubules depolymerize when encountering sharp cell edges head-on, whereas those oriented parallel to those sharp edges remain. Edge-induced microtubule depolymerization, however, is overcome by the microtubule-associated protein CLASP, which accumulates at specific cell edges, enables microtubule growth around sharp edges and promotes formation of microtubule bundles that span adjacent cell faces. By computationally modelling dynamic 'microtubules on a cube' with edges differentially permissive to microtubule passage, we show that the CLASP-edge complex is a 'tuneable' microtubule organizer, with the inherent flexibility to generate the numerous cortical array patterns observed in nature

The Fission Yeast XMAP215 Homolog Dis1p Is Involved in Microtubule Bundle Organization

Microtubules are essential for a variety of fundamental cellular processes such as organelle positioning and control of cell shape. Schizosaccharomyces pombe is an ideal organism for studying the function and organization of microtubules into bundles in interphase cells. Using light microscopy and electron tomography we analyzed the bundle organization of interphase microtubules in S. pombe. We show that cells lacking ase1p and klp2p still contain microtubule bundles. In addition, we show that ase1p is the major determinant of inter-microtubule spacing in interphase bundles since ase1 deleted cells have an inter-microtubule spacing that differs from that observed in wild-type cells. We then identified dis1p, a XMAP215 homologue, as factor that promotes the stabilization of microtubule bundles. In wild-type cells dis1p partially co-localized with ase1p at regions of microtubule overlap. In cells deleted for ase1 and klp2, dis1p accumulated at the overlap regions of interphase microtubule bundles. In cells lacking all three proteins, both microtubule bundling and inter-microtubule spacing were further reduced, suggesting that Dis1p contributes to interphase microtubule bundling

Microwave pulse compression using helically corrugated waveguides and its potential for generating ultra-high power RF radiation

The use of a helically corrugated waveguide as a dispersive medium for microwave pulse compression will be presented. The helically corrugated waveguide has a large variation in group-velocity with frequency, in a region far from cut-off. This compressor does not suffer from reflections associated with operation near to cut-off and therefore can be used at the output of a high-power microwave device. © 2004 IEEE

Waveguide system for high-power microwave pulse compression

X-band passive microwave pulse compression is an interesting area of research in vacuum electronics. Applications include radar technology, plasma diagnostics etc. [1] The scientific study of producing high-power nanosecond microwave pulses, using passive sweep-frequency compression, was undertaken. Two novel helically corrugated waveguides were investigated; 3-fold and 5-fold, respectively. The 3-fold structure couples a TE1,1 travelling wave with a near cut-off TE2,1 wave producing a region far from cut-off with a large change in group velocity as a function of frequency. A 2.08 metre long copper helical waveguide was used to compress a 80ns, 5.5kW frequency-swept pulse from a high power TWT (TMD PTC6321), driven by an arbitrary waveform generator and vector signal generator, to a 1.5ns, 135kW pulse containing similar to 75% of the energy of the input pulse. To enhance the power capabilities of the microwave pulse compressor a more overmoded larger diameter 5-fold helical waveguide structure which adiabatically couples a TE3,1 traveling wave and a near cut-off TE2,2 wave was studied. Analysis of the dispersion characteristics carried out using CST MWS will be presented