A novel pretherapeutic gene expression-based risk score for treatment guidance in gastric cancer

Background

Perioperative chemotherapy is an established treatment of advanced gastric cancer patients. Treatment selection is based on clinical staging (cT). We aimed to establish and validate a prognostic score including clinical and molecular factors, to optimize treatment decisions for these patients.

Patients and methods

We analyzed 626 carcinomas of the stomach and of the gastro-esophageal junction from two academic centers including primarily resected and pre-/perioperatively treated patients. Patients were divided into a training (N = 269) and validation (N = 357) set. Expression of 11 target genes was measured by quantitative PCR in resected tumors. A risk score to predict overall survival (OS) was generated and validated. Intra-tumoral heterogeneity was assessed by analyzing 50 tumor areas from 10 patients.

Results

A risk score including the expression of CCL5, CTNNB1, EXOSC3 and LZTR1 and the clinical parameters cT, tumor localization and histopathologic type suggested two groups with a significant difference in OS [hazard ratio (HR) 0.30; 95% confidence interval (CI) 0.17-0.52]. The risk score was successfully validated in an independent cohort (HR 0.32; 95% CI 0.21-0.51; P < 0.001) as well as in subgroups of primarily resected (HR 0.30; 95% CI 0.17-0.54; P < 0.001) and pre-/perioperatively treated patients (HR 0.37; 95% CI 0.17-0.81; P = 0.009). A significant difference in OS of high- and low-risk patients was also found in primarily resected patients with intestinal (HR 0.45; 95% CI 0.23-0.90; P = 0.020) and nonintestinal-type carcinomas (HR 0.1; 95% CI 0.02-0.42; P < 0.001). Intra-tumor heterogeneity analysis indicated a classification reliability of 95% for a supposed analysis of three biopsies.

Conclusion

The identified risk score could substantially contribute to an improved management of gastric cancer patients in the context of perioperative chemotherapy.

Coherent X-ray diffraction imaging and characterization of strain in silicon-on-insulator nanostructures

Coherent X-ray diffraction imaging (CDI) has emerged in the last decade as a promising high resolution lens-less imaging approach for the characterization of various samples. It has made significant technical progress through developments in source, algorithm and imaging methodologies thus enabling important scientific breakthroughs in a broad range of disciplines. In this report, we will introduce the principles of forward scattering CDI and Bragg geometry CDI (BCDI), with an emphasis on the latter. BCDI exploits the ultra-high sensitivity of the diffraction pattern to the distortions of crystalline lattice. Its ability of imaging strain on the nanometer scale in three dimensions is highly novel. We will present the latest progress on the application of BCDI in investigating the strain relaxation behavior in nanoscale patterned strained silicon-on-insulator (sSOI) materials, aiming to understand and engineer strain for the design and implementation of new generation semiconductor devices.

Direct optical mapping of anisotropic stresses in nanowires using transverse optical phonon splitting

Strain engineering is ubiquitous in the design and fabrication of innovative, high-performance electronic, optoelectronic, and photovoltaic devices. The increasing importance of strain-engineered nanoscale materials has raised significant challenges at both fabrication and characterization levels. Raman scattering spectroscopy (RSS) is one of the most straightforward techniques that have been broadly utilized to estimate the strain in semiconductors. However, this technique is incapable of measuring the individual components of stress, thus only providing the average values of the in-plane strain. This inherit limitation severely diminishes the importance of RSS analysis and makes it ineffective in the predominant case of nanostructures and devices with a nonuniform distribution of strain. Herein, we circumvent this major limitation and demonstrate for the first time the application of RSS to simultaneously probe the two local stress in-plane components in individual ultrathin silicon nanowires based on the imaging of the splitting of the two forbidden transverse optical phonons.

Weitere aus dem Kulturmedium von Pseudomonas putida isolierte Pyridinderivate -Genuine Metaboliten oder Artefakte ?/Further Pyridine Derivatives Isolated from the Culture Medium of Pseudomonas putida - Genuine Metabolites or Artefacts ?

From the culture medium of Pseudomonas putida after treatment with CH2N2 besides the expected Pyridine-2,6-di(monothiocarboxylic acid)-di-S-methyl ester a series of pyridine derivatives could be isolated which could be shown to be artefacts formed from pyridine-2,6-di(monothiocarboxylic acid).

Improving accuracy and precision of strain analysis by energy-filtered nanobeam electron diffraction

This article deals with uncertainty in the analysis of strain in silicon nanoscale structures and devices using nanobeam electron diffraction (NBED). Specimen and instrument related errors and instabilities and their effects on NBED analysis are addressed using a nanopatterned ultrathin strained silicon layer directly on oxide as a model system. We demonstrate that zero-loss filtering significantly improves the NBED precision by decreasing the diffuse background in the diffraction patterns. To minimize the systematic deviations the acquired data were verified through a reliability test and then calibrated. Furthermore, the effect of strain relaxation by specimen preparation using a FIB is estimated by comparing profiles, which were acquired by analyzing slices of strained structures in a 220-nm-thick region of the sample (invasive preparation) and the entire strained nanostructures, which are embedded in a thicker region of the same sample (noninvasive preparation). Together with the random deviation, the corresponding systematic shift results in a total deviation of ∼1 × 10(-3) for NBED analyses, which is employed to estimate the measurement uncertainty in the thinner sample region. In contrast, the strain in the thick sample region is not affected by the preparation; the systematic shift reduces to a minimum, which improves the total deviation by ∼50%.

Mapping the "forbidden" transverse-optical phonon in single strained silicon (100) nanowire

The accurate manipulation of strain in silicon nanowires can unveil new fundamental properties and enable novel or enhanced functionalities. To exploit these potentialities, it is essential to overcome major challenges at the fabrication and characterization levels. With this perspective, we have investigated the strain behavior in nanowires fabricated by patterning and etching of 15 nm thick tensile strained silicon (100) membranes. To this end, we have developed a method to excite the "forbidden" transverse-optical (TO) phonons in single tensile strained silicon nanowires using high-resolution polarized Raman spectroscopy. Detecting this phonon is critical for precise analysis of strain in nanoscale systems. The intensity of the measured Raman spectra is analyzed based on three-dimensional field distribution of radial, azimuthal, and linear polarizations focused by a high numerical aperture lens. The effects of sample geometry on the sensitivity of TO measurement are addressed. A significantly higher sensitivity is demonstrated for nanowires as compared to thin layers. In-plane and out-of-plane strain profiles in single nanowires are obtained through the simultaneous probe of local TO and longitudinal-optical (LO) phonons. New insights into strained nanowires mechanical properties are inferred from the measured strain profiles.

Large-area porous alumina photonic crystals via imprint method

A perfect 2D porous alumina photonic crystal with 500 nm interpore distance was fabricated on an area of 4 cm2 via imprint methods and subsequent electrochemical anodization. A 4” imprint stamp consisting of a convex pyramid array was obtained by modern VLSI processing using DUV-lithography, anisotropic etching, LPCVD Si3N4 deposition and wafer bonding. The optical properties of the porous alumina photonic crystal were measured with an infrared microscope in Г-M direction. For both polarizations, a bandgap is observed at around 1 μm for r/a = 0.42. A reflectivity of almost unity for E-polarization in the region of the bandgap is a sign of the high quality of the structure, indicating almost no scattering losses. These experimental results could be correlated very well to the bandstructure as well as reflectivity calculations assuming a dielectric constant of å = 2.0 for the anodized alumina.

Observation of free surface-induced bending upon nanopatterning of ultrathin strained silicon layer

We provide evidence of nanopatterning-induced bending of an ultrathin tensile strained silicon layer directly on oxide. This strained layer is achieved through the epitaxial growth of silicon on a Si(0.84)Ge(0.16) virtual substrate and subsequent transfer onto a SiO(2)-capped silicon substrate by combining hydrophilic wafer bonding and the ion-cut process. Using high resolution transmission electron microscopy, we found that the upper face of the strained silicon nanostructures fabricated from the obtained heterostructure using electron beam lithography and dry reactive ion etching displays a concave shape. This bending results from the free-surface-induced strain relaxation, which implies lattice out-of-plane expansion near the edges and concomitant contraction at the center. For a ∼ 110 nm × 400 nm × 20 nm nanostructure, the bending is associated with an angle of 1.5° between the [Formula: see text] vertical atomic planes at the edges of the ∼ 110 nm side. No bending is, however, observed at the strained Si/SiO(2) interface. This phenomenon cannot be explained by the classical Stoney's formula or related formulations developed for nanoscale thin films. Here we employed a continuum mechanical approach to describe these observations using three-dimensional numerical calculations of relaxation-induced lattice displacements.

Serum levels of the adipokine lipocalin-2 are increased in preeclampsia

BACKGROUND

Preeclampsia (PE) is a serious complication in pregnancy which increases the future risk for vascular and metabolic disease in both mother and newborn. Recently, lipocalin-2 has been introduced as a novel adipokine which contributes to obesity, insulin resistance, and vascular disease.

AIM

In the current study, we investigated lipocalin-2 serum levels in PE patients as compared to healthy gestational age-matched controls.

SUBJECTS AND METHODS

Lipocalin-2 serum concentrations were quantified by enzyme-linked immunosorbent assay in control (no.=22) and PE (no.=22) patients. Furthermore, lipocalin-2 levels were correlated to clinical and biochemical measures of renal function, glucose, and lipid metabolism, as well as inflammation.

RESULTS

Median maternal lipocalin-2 concentrations were significantly increased in PE (121.3 μg/l) as compared to control subjects (99.8 μg/l) (p<0.05). Furthermore, circulating lipocalin 2 correlated positively with diastolic blood pressure, creatinine, and C reactive protein. In multivariate analyses, creatinine and C reactive protein remained independently associated with lipocalin-2 levels.

CONCLUSIONS

We demonstrate that maternal lipocalin-2 concentrations are significantly increased in PE. Furthermore, markers of renal function and inflammation independently predict circulating lipocalin-2.

Nanoscale patterning induced strain redistribution in ultrathin strained Si layers on oxide

We present a comparative study of the influence of the thickness on the strain behavior upon nanoscale patterning of ultrathin strained Si layers directly on oxide. The strained layers were grown on a SiGe virtual substrate and transferred onto a SiO(2)/Si substrate using wafer bonding and hydrogen ion induced exfoliation. The post-patterning strain was evaluated using UV micro-Raman spectroscopy for thin (20 nm) and thick (60 nm) nanostructures with lateral dimensions in the range of 80-400 nm. We found that about 40-50% of the initial strain is maintained in the 20 nm thick nanostructures, whereas this fraction drops significantly to approximately 2-20% for the 60 nm thick ones. This phenomenon of free surface induced relaxation is described using detailed three-dimensional finite element simulations. The simulated strain 3D maps confirm the limited relaxation in thin nanostructures. This result has direct implications for the fabrication and manipulation of strained Si nanodevices.

Fibroblast growth factor 19 serum levels: relation to renal function and metabolic parameters

Fibroblast growth factor 19 (FGF19) was recently introduced as a novel metabolic regulator reversing diabetes mellitus, hepatic steatosis, hyperlipidemia, and adiposity. In the current study, we determined circulating FGF19 levels in patients on chronic hemodialysis (CD) as compared to controls with a glomerular filtration rate (GFR) above 50 ml/min. FGF19 was measured by ELISA in control (n=60) and CD (n=60) patients and correlated to clinical and biochemical measures of renal function, glucose, and lipid metabolism, as well as inflammation, in both groups. Median serum FGF19 levels were 1.5-fold higher in CD patients (266.7 microg/l) as compared to subjects with a GFR above 50 ml/min (178.1 microg/l) (p=0.001). Furthermore, fasting glucose negatively and independently predicted circulating FGF19 in controls (p<0.05). Moreover, adiponectin was a positive and C-reactive protein was a negative independent predictor of FGF19 serum concentrations in CD patients. Taken together, we have demonstrated that circulating FGF19 levels are significantly increased in end-stage renal disease. Furthermore, FGF19 is associated with a beneficial metabolic profile in both control and CD patients.

Sub-20 nm Si/Ge superlattice nanowires by metal-assisted etching

An effective and low-cost method to fabricate hexagonally patterned, vertically aligned Si/Ge superlattice nanowires with diameters below 20 nm is presented. By combining the growth of Si/Ge superlattices by molecular beam epitaxy, prepatterning the substrate by anodic aluminum oxide masks, and finally metal-assisted chemical wet etching, this method generates highly ordered hexagonally patterned nanowires. This technique allows the fabrication of nanowires with a high area density of 10(10) wires/cm(2), including the control of their diameter and length.

Extended arrays of vertically aligned sub-10 nm diameter [100] Si nanowires by metal-assisted chemical etching

Large-area high density silicon nanowire (SiNW) arrays were fabricated by metal-assisted chemical etching of silicon, utilizing anodic aluminum oxide (AAO) as a patterning mask of a thin metallic film on a Si (100) substrate. Both the diameter of the pores in the AAO mask and the thickness of the metal film affected the diameter of SiNWs. The diameter of the SiNWs decreased with an increase of thickness of the metal film. Large-area SiNWs with average diameters of 20 nm down to 8 nm and wire densities as high as 10 (10) wires/cm (2) were accomplished. These SiNWs were single crystalline and vertically aligned to the (100) substrate. It was revealed by transmission electron microscopy that the SiNWs were of high crystalline quality and showed a smooth surface.

Regular dislocation networks in silicon as a tool for nanostructure devices used in optics, biology, and electronics

Well-controlled fabrication of dislocation networks in Si using direct wafer bonding opens broad possibilities for nanotechnology applications. Concepts of dislocation-network-based light emitters, manipulators of biomolecules, gettering and insulating layers, and three-dimensional buried conductive channels are presented and discussed. A prototype of a Si-based light emitter working at a wavelength of about 1.5 microm with an efficiency potential estimated at 1% is demonstrated.

[Prenatal diagnosis and management of fetal arrhythmias]

Reported in this paper are 25 cases of fetal arrhythmia handled at the Gynaecological Department of the Berlin School of Medicine (Charité) over a period of two years. They were subdivided by tachycardiac, bradycardiac, and simple forms, following ultrasound-assisted diagnosis (realtime, M-Mode, Doppler). This proved to be useful for better prenatal management and prognosis. The first and second forms were linked to higher rates of malformations or contributory and recordable causes, whereas the third form could be considered harmless, the more as spontaneous postnatal regression was to be expected. Successful experience is reported, as obtained from prenatal therapy either via the mother or by direct invasive treatment to the child (thigh, umbilical vein). Early referral to an adequately staffed and equipped centre and exclusion of cardiac defects are conditions for good success. Intrauterine deaths occurred in two cases due to cardiac malformations, and non-immunological fetal hydrops was established in four cases. Optimal management of the inhomogenous group of fetal arrhythmias should be undertaken in interdisciplinary teamwork at centres with experience in perinatal medicine.