Capturing Linear Intermediates and C-Terminal Variants during Maturation of the Thiopeptide GE2270

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Multiplex genotyping of KRAS point mutations in tumor cell DNA by allele-specific real-time PCR on a centrifugal microfluidic disk segment

Point Mutations on the Kirsten rat sarcoma viral oncogene homolog (KRAS) have been identified as an important predictive biomarker for response to cancer therapy targeting the epidermal growth factor receptor. KRAS mutations are prevalent in up to 40 % of all colorectal carcinomas, and routinely conducted KRAS genotyping is becoming mandatory to predict therapy success and to reduce therapy costs. We report a low-cost, disposable and ready-to-use centrifugal microfluidic cartridge (termed GeneSlice) containing preloaded primers and probes. The GeneSlice cartridge enables the parallel detection of the seven most relevant KRAS point mutations by allele-specific real-time PCR. It represents a cost effective alternative to dideoxy-sequencing with a faster time-to-result (~ 2 h versus up to 20 h in case of dd-sequencing). Microfluidic processing of the GeneSlice along with allele-specific amplification and real-time detection are conducted in a slightly modified, commercially available PCR thermocycler. Intra-chip standard deviation of C_q values on the GeneSlices is negligible (GeneSlice 1: C_q,std.dev. = 0.13; GeneSlice 2: C_q,std.dev?=?0.26). In 23 of 24 experiments, the data for genotyping 6 cancer cell lines (n?=?4 per cell line) agreed with dd-sequencing. Additionally, DNA derived from microdissected formalin-fixed and paraffin embedded colorectal carcinomas of two cases was genotyped correctly and reproducibly (n?=?3 per patient; one GeneSlice excluded from evaluation). The GeneSlice therefore clearly demonstrated the potential to become a valuable tool for routine diagnostics of KRAS mutations by reducing costs and hands-on time. Figure

Photograph of a centrifugal microfluidic cartridge “GeneSlice” for multiplex genotyping of KRAS point mutations from tumor cell DNA by allele-specific real-time PCR. Information about the mutation status is required to predict success of state-of-the-art cancer therapy with antibodies     

Measurement of stimulated Hawking emission in an analogue system

Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. To address this issue experimentally, we utilize the analogy between the propagation of fields around black holes and surface waves on moving water. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include surface wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep-water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process.     

Spectral dimension as a probe of the ultraviolet continuum regime of causal dynamical triangulations

We explore the ultraviolet continuum regime of causal dynamical triangulations, as probed by the flow of the spectral dimension. We set up a framework in which one can find continuum theories that can in principle fully reproduce the behavior of the latter in this regime. In particular, we show that, in 2 + 1 dimensions, Ho?ava-Lifshitz gravity can mimic the flow of the spectral dimension in causal dynamical triangulations to high accuracy and over a wide range of scales. This seems to provide evidence for an important connection between the two theories.     

Unexpected Coordination Behaviour of a Polypyrrole Ligand

The first coordination compounds of a hexapyrrin reveal an unexpected binding mode of longer open‐chain oligopyrroles to transition metal ions as observed by the X‐ray structural analysis of a Pd^II derivative.     

Vector bundles of degree zero over an elliptic curveFibrés vectoriels de degré zéro sur une courbe elliptique

In this Note we study indecomposable vector bundles of degree zero over an elliptic curve. We show that each bundle generates a ring and a Tannakian category, such that the ring and the group scheme associated to the Tannakian category are of the same dimension. Furthermore we show that the result does not extend to curves of genus 2. To cite this article: S. Lekaus, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 351–354.     

Ba6Ge25: low-temperature Ge-Ge bond breaking during temperature-induced structure transformation

In order to find the optimal conditions for sample preparation of the binary germanide Ba₆Ge₂₅, the germanium-rich part of the Ba-Ge phase diagram was redetermined by means of metallography, X-ray powder diffraction and differential thermal analysis. The temperature behavior of cubic Ba₆Ge₂₅ was investigated both on polycrystalline samples and single crystals. The temperature dependence of the lattice parameter exhibits two anomalies at about 180 and 230 K, respectively, which are caused by a structure transformation in two steps with hysteresis. Powder (T=10-295 K) and single-crystal (T=95-295 K) X-ray diffraction studies confirm that the symmetry of Ba₆Ge₂₅ (space group P4₁32) remains unchanged within the entire temperature range. A reconstructive behavior of the structural transformation is observed, involving Ge-Ge bond breaking and barium cation displacements. Some Ge4 type atoms (∼28%) are so significantly displaced during cooling that Ge4-Ge6 bonds break and new three-bonded (3b)Ge⁻ species (electron acceptors) are formed. Consequently, the number of charge carriers is reduced, affecting the physical properties. The reversible bond breaking involved in this process is a typical characteristic of a solid-state chemical reaction.     

The computer as “an exercise and repetition” medium in mathematics lessons: Educational Effectiveness of Tablet PCs

The request of a new educational culture within the classroom goes hand in hand with the introduction of the new Educational Standards. That is they are essentially connected with a paradigm shift. The Project supports this aim via different tasks administered through Tablet PC's within the scope of exercise and repetition phase of learning. The central concern is to find appropriate lesson approaches through computer use in everyday life at school, which are conductive for the math learners and are at the same time easy to effectively implement in other classrooms. In the summer of 2004 the use of Tablet-PCs in school took place in two 9th classes of an Ostalbkreis secondary school in Baden-Württenberg. We report on the effectiveness of this new technology in the classroom.