On-chip wavelength multiplexed detection of cancer DNA biomarkers in blood

We have developed an optofluidic analysis system that processes biomolecular samples starting from whole blood and then analyzes and identifies multiple targets on a silicon-based molecular detection platform. We demonstrate blood filtration, sample extraction, target enrichment, and fluorescent labeling using programmable microfluidic circuits. We detect and identify multiple targets using a spectral multiplexing technique based on wavelength-dependent multi-spot excitation on an antiresonant reflecting optical waveguide chip. Specifically, we extract two types of melanoma biomarkers, mutated cell-free nucleic acids -BRAFV600E and NRAS, from whole blood. We detect and identify these two targets simultaneously using the spectral multiplexing approach with up to a 96% success rate. These results point the way toward a full front-to-back chip-based optofluidic compact system for high-performance analysis of complex biological samples.

MR Image Reconstruction Using a Combination of Compressed Sensing and Partial Fourier Acquisition: ESPReSSo

A Cartesian subsampling scheme is proposed incorporating the idea of PF acquisition and variable-density Poisson Disc (vdPD) subsampling by redistributing the sampling space onto a smaller region aiming to increase k-space sampling density for a given acceleration factor. Especially the normally sparse sampled high-frequency components benefit from this sampling redistribution, leading to improved edge delineation. The prospective subsampled and compacted k-space can be reconstructed by a seamless combination of a CS-algorithm with a Hermitian symmetry constraint accounting for the missing part of the k-space. This subsampling and reconstruction scheme is called Compressed Sensing Partial Subsampling (ESPReSSo) and was tested on in-vivo abdominal MRI datasets. Different reconstruction methods and regularizations are investigated and analyzed via global (intensity-based) and local (region-of-interest and line evaluation) image metrics, to conclude a clinical feasible setup. Results substantiate that ESPReSSo can provide improved edge delineation and regional homogeneity for multidimensional and multi-coil MRI datasets and is therefore useful in applications depending on well-defined tissue boundaries, such as image registration and segmentation or detection of small lesions in clinical diagnostics.

Enhancement of ARROW Photonic Device Performance via Thermal Annealing of PECVD-based SiO2 Waveguides

Silicon-based optofluidic devices are very attractive for applications in biophotonics and chemical sensing. Understanding and controlling the properties of their dielectric waveguides is critical for the performance of these chips. We report that thermal annealing of PECVD-grown silicon dioxide (SiO2) ridge waveguides results in considerable improvements to optical transmission and particle detection. There are two fundamental changes that yield higher optical transmission: (1) propagation loss in solid-core waveguides is reduced by over 70%, and (2) coupling efficiencies between solid- and liquid-core waveguides are optimized. The combined effects result in improved optical chip transmission by a factor of 100-1000 times. These improvements are shown to arise from the elimination of a high-index layer at the surface of the SiO2 caused by water absorption into the porous oxide. The effects of this layer on optical transmission and mode confinement are shown to be reversible by alternating subjection of waveguides to water and subsequent low temperature annealing. Finally, we show that annealing improves detection of fluorescent analytes in optofluidic chips with a signal-to-noise ratio improvement of 166x and a particle detection efficiency improvement of 94%.

Antimicrobial efficacy of sequentially applied eugenol against food spoilage micro-organisms

AIMS

Compare the survival behaviour of food spoilage micro-organisms treated with sequential doses or all at once treatments of eugenol.

METHODS AND RESULTS

Staphylococcus carnosus, Listeria innocua, Escherichia coli and Pseudomonas fluorescens were exposed to a minimal lethal concentration (MLC) initially, or to half doses over time, with first half dose applied immediately and a second half dose applied after 3, 4, 6 and 8 h, of eugenol. Direct plate counts were determined at regular time intervals. Population dynamics were analysed using a combined growth and mortality model. Effect of sequential dosing varied significantly between tested organisms. High antimicrobial efficacy on E. coli K12 was observed regardless of timing of the two doses. Reduced effectiveness was observed against Staph. carnosus and L. innocua the later the second half dose was applied. Complete cell reduction occurred after immediate exposure to full MLC dose, while sequential half doses were bacteriostatic regardless of application times.

CONCLUSION

Time in between antimicrobial dose application had substantial impact on effectiveness, attributed to organisms becoming more tolerant.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study contributes to the evaluation of encapsulated antimicrobial systems, where antimicrobials are released over time and antimicrobial concentrations may only reach MLC levels after some time.

Lateral femoral cutaneous nerve block after total hip arthroplasty: a randomised trial

BACKGROUND

Peripheral regional nerve blocks are commonly used for pain management after lower extremity surgery, but motor blockade can be a significant concern. The lateral femoral cutaneous nerve (LFCN) is a purely sensory nerve from the lumbar plexus. We hypothesised that an LFCN block would reduce movement-related pain after total hip arthroplasty (THA) in patients with moderate-to-severe pain.

METHODS

Sixty patients with visual analogue scale (VAS) score > 40 mm during 30-degree active flexion of the hip on either the first or second postoperative day after THA were included in this prospective, randomised, blinded, placebo-controlled trial. Group A received an LFCN block with 8 ml of 0.75% ropivacaine followed after 45 min by an additional LFCN block with 8 ml of saline. Group B received an LFCN block with 8 ml of saline followed after 45 min by an additional LFCN block with 8 ml of 0.75% ropivacaine.

RESULTS

We found a difference of 17 mm (95% CI, 4-31 mm; P < 0.02) in VAS pain score during 30-degree flexion of the hip 45 min after the first block (primary outcome) in favour of group A. No other significant difference between groups regarding pain during mobilisation and at rest was found. The overall non-responder rate (< 15 mm pain reduction) was 42%.

CONCLUSIONS

LFCN block reduced movement-related pain in patients with moderate-to-severe pain after THA. The substantial non-responder rate limits recommendations of this block as part of a standard analgesic treatment regimen.

[Expert recommendations: Hepatitis C and transplantation]

With the approval of new direct acting antiviral agents (DAA), therapeutic options for patients with chronic hepatitis C virus (HCV) infection are now generally available before and after liver transplantation (LT). Interferon-free DAA regimens are highly effective therapies and provide a good safety profile. However, the body of clinical evidence in this patient population is limited and the best treatment strategies for patients on the waiting list with (de)compensated cirrhosis and after LT are not well defined. The following recommendations for antiviral therapy in the context of LT are based on the currently available literature and clinical experience of experts in the field, and have been discussed in an expert meeting. The aim of this article is to guide clinicians in the decision making when treating patients before and after LT with DAAs.

Computation of the pressure field generated by surface acoustic waves in microchannels

The high-frequency pressure induced by a surface acoustic wave in the fluid filling a microchannel is computed by solving the full scattering problem. The microchannel is fabricated inside a container attached to the top of a piezoelectric substrate where the surface wave propagates. The finite element method is used. The pressure found in this way is compared with the pressure obtained by solving boundary-value problems formulated on the basis of simplifications which have been introduced in earlier papers by other research studies. The considered example shows that the difference between the results can be significant, ranging from several tens of percent up to several times in different points inside the channel.

Perforated hollow-core optical waveguides for on-chip atomic spectroscopy and gas sensing

A hollow-core waveguide structure for on-chip atomic spectroscopy is presented. The devices are based on Anti-Resonant Reflecting Optical Waveguides and may be used for a wide variety of applications which rely on the interaction of light with gases and vapors. The designs presented here feature short delivery paths of the atomic vapor into the hollow waveguide. They also have excellent environmental stability by incorporating buried solid-core waveguides to deliver light to the hollow cores. Completed chips were packaged with an Rb source and the F = 3 ≥ F' = 2, 3, 4 transitions of the D2 line in ⁸⁵Rb were monitored for optical absorption. Maximum absorption peak depths of 9% were measured.

Combined PET/MR: The Real Work Has Just Started. Summary Report of the Third International Workshop on PET/MR Imaging; February 17-21, 2014, Tübingen, Germany

This paper summarises the proceedings and discussions at the third annual workshop held in Tübingen, Germany, dedicated to the advancement of the technical, scientific and clinical applications of combined PET/MRI systems in humans. Two days of basic scientific and technical instructions with "hands-on" tutorials were followed by 3 days of invited presentations from active researchers in this and associated fields augmented by round-table discussions and dialogue boards with specific themes. These included the use of PET/MRI in paediatric oncology and in adult neurology, oncology and cardiology, the development of multi-parametric analyses, and efforts to standardise PET/MRI examinations to allow pooling of data for evaluating the technology. A poll taken on the final day demonstrated that over 50 % of those present felt that while PET/MRI technology underwent an inevitable slump after its much-anticipated initial launch, it was now entering a period of slow, progressive development, with new key applications emerging. In particular, researchers are focusing on exploiting the complementary nature of the physiological (PET) and biochemical (MRI/MRS) data within the morphological framework (MRI) that these devices can provide. Much of the discussion was summed up on the final day when one speaker commented on the state of PET/MRI: "the real work has just started".