Development and in-vitro characterization of an implantable flow sensing transducer for hydrocephalus

An implantable transducer for monitoring the flow of Cerebrospinal fluid (CSF) for the treatment of hydrocephalus has been developed which is based on measuring the heat dissipation of a local thermal source. The transducer uses passive telemetry at 13.56MHz for power supply and read out of the measured flow rate. The in vitro performance of the transducer has been characterized using artificial Cerebrospinal Fluid (CSF) with increased protein concentration and artificial CSF with 10% fresh blood. After fresh blood was added to the artificial CSF a reduction of flow rate has been observed in case that the sensitive surface of the flow sensor is close to the sedimented erythrocytes. An increase of flow rate has been observed in case that the sensitive surface is in contact with the remaining plasma/artificial CSF mix above the sediment which can be explained by an asymmetric flow profile caused by the sedimentation of erythrocythes having increased viscosity compared to artificial CSF. After removal of blood from artificial CSF, no drift could be observed in the transducer measurement which could be associated to a deposition of proteins at the sensitive surface walls of the packaged flow transducer. The flow sensor specification requirement of +−10% for a flow range between 2ml/h and 40ml/h. could be confirmed at test conditions of 37°

Capillary-valve-based platform towards cell-on-chip mechanotransduction assays

Reliable in vitro models are required to understand the ability of cells to respond and adapt to mechanical stimuli. To mimic and interface with the microenvironment, lab-on-a-chip devices and microelectromechanical systems (MEMS) provide excellent options. However, little effort has been done in combining them. To address this shortcoming, we have developed a versatile microengineered platform which consists of two parts: an electrostatically actuated MEMS device used for mechanobiology assays, and a fluidic system for cell culture. A capillary valve allows inserting a silicon chip horizontally in the culture medium without leakage and without wetting of the electrostatic microactuators. The platform is designed for mechanotransduction assay on cells and aims specifically human mesenchymal stem cells. The proof of principle of the platform was performed by stable and long-term cultures of rat fibroblasts. We could also study the effect of periodic stress at various excitation frequencies

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

HERMES : revisions in the design for a high-resolution multi-element spectrograph for the AAT

The AAO is building an optical high resolution multi-object spectrograph for the AAT for Galactic Archaeology. The instrument has undergone significant design revision over that presented at the 2008 Marseilles SPIE meeting. The current design is a 4-channel VPH-grating based spectrograph providing a nominal spectral resolving power of 28,000 and a high-resolution mode of 45,000 with the use of a slit mask. The total spectral coverage is about 1000 Angstroms for up to 392 simultaneous targets within the 2 degree field of view. Major challenges in the design include the mechanical stability, grating and dichroic efficiencies, and fibre slit relay implementation. An overview of the current design and discussion of these challenges is presented.19 page(s

HERMES: revisions in the design for a high-resolution multi-element spectrograph for the AAT

The AAO is building an optical high resolution multi-object spectrograph for the AAT for Galactic Archaeology. The instrument has undergone significant design revision over that presented at the 2008 Marseilles SPIE meeting. The current design is a 4-channel VPH-grating based spectrograph providing a nominal spectral resolving power of 28,000 and a high-resolution mode of 45,000 with the use of a slit mask. The total spectral coverage is about 1000 Angstroms for up to 392 simultaneous targets within the 2 degree field of view. Major challenges in the design include the mechanical stability, grating and dichroic efficiencies, and fibre slit relay implementation. An overview of the current design and discussion of these challenges is presented.19 page(s