Sensitive detection of hydroxymethylcytosine levels in normal and neoplastic cells and tissues

A new sensitive analytical method using capillary electrophoresis with laser induced fluorescence (CE‐LIF) was applied for the simultaneous detection of DNA methylation and hydroxymethylation levels in human cancers of different origin. DNA hydroxymethylation, measured as 5‐hydroxymethylcytosine (5hmC) levels, was decreased in gliomas with mutation in the isocitrate dehydrogenase 1 (IDH1) gene when compared to IDH1‐wildtype gliomas. Independent from IDH1 mutation, 5hmC levels were decreased in lung carcinomas when compared to normal lung tissue. Reduced DNA hydroxymethylation was also observed upon dedifferentiation in cultured murine embryonic fibroblasts. Our data show that reduced DNA hydroxymethylation is related to cellular dedifferentiation and can be detected in various types of cancers, independent from the IDH1 mutation status. Quantitative determination of altered 5hmC levels may therefore have potential as a biomarker linked to cellular differentiation and tumorigenesis.     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)-Komplexe mit verschiedenen 1H-Phosphiren-Liganden,Kristallstrukturen von,und

Synthesis and Spectroscopic Characterization of some Pentacarbonyltungsten(0) Complexes with Various 1H-Phosphirene Ligands: Crystal Structures of , and The tungsten(0) complex 1 reacts upon heating with acetylene derivatives 2a–f in toluene to form benzonitrile and the complexes 4a–f ( 4a : R¹ ? Ph, R² ? H; 4b : R¹ ? Ph, R² ? CH₃; 4c : R¹ ? OEt, R² ? H; 4d : R¹ ? Ph, R² ? CO₂Et; 4e : R¹, R² ? CO₂Me; 4f : R¹, R² ? SiMe₃), which have been isolated by chromatography. Spectroscopic and mass spectrometric data are discussed. The crystal structures of the compounds 4a, b and d were determined by X-ray single crystal structure analysis ( 4a : space group P2₁/n, Z = 4, a = 937,5(2) pm, b = 2202,4(6) pm, c = 1266,3(4) pm, β = 108,94(4)°; 4b : space group P2₁/c, Z = 4, a = 1293,9(2) pm, b = 923,5(1) pm, c = 2223,4(3) pm, β = 92,385(6)°; 4d : space group P2₁/c, Z = 4, a = 955,2(2) pm, b = 3190,9(4) pm, c = 930,7(2) pm, β = 99,64(1)°).     

Covalent modification of a metal-organic framework with isocyanates: probing substrate scope and reactivity

Isoreticular metal-organic framework-3 (IRMOF-3) has been postsynthetically modified with isocyanates to generate unprecedented, microporous urea-functionalized frameworks.     

Capillary electrophoresis-based immunoassays: principles and quantitative applications

The use of CE as a tool to conduct immunoassays has been an area of increasing interest over the last decade. This approach combines the efficiency, small sample requirements, and relatively high speed of CE with the selectivity of antibodies as binding agents. This review examines the various assay formats and detection modes that have been reported for these assays, along with some representative applications. Most CE immunoassays in the past have employed homogeneous methods in which the sample and reagents are allowed to react in solution. These homogeneous methods have been conducted as both competitive binding immunoassays and as noncompetitive binding immunoassays. Fluorescent labels are most commonly used for detection in these assays, but enzyme labels have also been utilized for such work. Some additional work has been performed in CE immunoassays with heterogeneous methods in which either antibodies or an analog of the analyte is immobilized to a solid support. These heterogeneous methods can be used for the selective isolation of analytes prior to their separation by CE or to remove a given species from a sample/reagent mixture prior to analysis by CE. These CE immunoassays can be used with a variety of detection modes, such as fluorescence, UV/Vis absorbance, chemiluminescence, electrochemical measurements, MS, and surface plasmon resonance.     

Structural effects on interconversion of oxygen-substituted bisketenes and cyclobutenediones

Cyclobutenediones 5 disubstituted with HO (a), MeO (b), EtO (c), i-PrO (d), t-BuO (e), PhO (f), 4-MeOC6H4O (g), 4-O2NC6H4O (h), and 3,4-bridging OCH2CH2O (i) substituents upon laser flash photolysis gave the corresponding bisketenes 6a-i, as detected by their distinctive doublet IR absorptions between 2075 and 2106 and 2116 and 2140 cm-1. The reactivities in ring closure back to the cyclobutenediones were greatest for the group 6b-e, with the highest rate constant of 2.95 x 10(7) s-1 at 25 degrees C for 6e (RO = t-BuO) in isooctane, were less for 6a (RO = OH, k = 2.57 x 10(6) s-1 in CH3CN), while 6f-i were the least reactive, with the lowest rate constant of 3.8 x 10(4) s-1 in CH3CN for 6h (RO = 4-O2NC6H4O). The significantly reduced rate constants for 6f-i are attributed to diminution of the electron-donating ability of oxygen to the cyclobutenediones 5f-h by the ArO substituents compared to alkoxy groups and to angle strain in the bridged product cyclobutenedione 5i. The reactivities of the ArO-substituted bisketenes 6f-h in CH3CN varied by a factor of 50 and gave an excellent correlation of the observed rate constants log k with the sigma p constants of the aryl substituents. Computational studies at the B3LYP/6-31G(d) level of ring-closure barriers are consistent with the measured reactivities. Photolysis of squaric acid (5a) in solution provides a convenient preparation of deltic acid (7).     

A briefing on aurophilicity

There is now compelling experimental evidence for the existence of specific intra- and intermolecular bonding between seemingly closed-shell gold(i) centers (5d(10)) which manifests itself in all areas of gold chemistry. This "aurophilic interaction", which had not been predicted by conventional valence theory, was found to be associated with binding energies in some cases exceeding even those of strong hydrogen bonds and therefore to be highly significant in co-determining molecular structure and dynamics. In high-level theoretical treatments the attraction is rationalized as a "super van der Waals bonding" based on particularly strong relativistic, dispersion and correlation effects (critical review, 265 references).     

Artificial chemokines: combining chemistry and molecular biology for the elucidation of interleukin-8 functionality

How can we understand the contribution of individual parts or segments to complex structures? A typical strategy to answer this question is simulation of a segmental replacement followed by realization and investigation of the resulting effect in structure-activity studies. For proteins, this problem is commonly addressed by site-directed mutagenesis. A more general approach represents the exchange of whole secondary structure elements by rationally designed segments. For a demonstration of this possibility we identified the alpha-helix at the C-terminus of human interleukin-8 (hIL-8). Since this chemokine possesses four conserved cysteine residues, it can easily be altered by ligation strategies. A set of different segments, which are able to form amphiphilic helices, was synthesized to mimic the C-terminal alpha-helix. Beside sequences of alpha-amino acids, oligomers of non-natural beta(3)-amino acids with the side chains of canonical amino acids were introduced. Such beta-peptides form helices, which differ from the alpha-helix in handedness and dipole orientation. Variants of the semisynthetic hIL-8 proteins demonstrated clearly that the exact side chain orientation is of more importance than helix handedness and dipole orientation. The activity of a chimeric protein with a beta-peptide helix that mimics the side chain orientation of the native alpha-helix most perfectly is comparable to that of the native hIL-8. Concepts like this could be a first step toward the synthesis of proteins consisting of large artificial secondary structure elements.     

Measuring pre-service teachers’ self-efficacy in tutoring children in primary mathematics: an instrument

This article reports on the use of Rasch modelling to develop and validate an instrument measuring self-efficacy in tutoring children in primary mathematics (SETcPM). In response to the literature on teacher efficacy, the 20-item instrument aims to inform teacher educators, and is designed for novice pre-service teachers (nPSTs) preparing to teach mathematics in primary school (grades 1–7, ages 6–13). To ensure that the tasks of teaching are imaginable for nPSTs, the instrument targets the core activity of teaching mathematics: helping a generic child with mathematics tasks. We propose that SETcPM is measurable for the intended population and represents a central part of self-efficacy in teaching mathematics (SETM). Understanding the initial SETcPM of novices and mapping its development over the course of their training programme can contribute to a better understanding of SETM, and allow teacher educators to tailor their support.     

A new search for the atomic EDM of 129Xe at FRM-II

Permanent electric dipole moments (EDMs) arise due to the breaking of time-reversal or, equivalently, CP-symmetry. Although EDM searches have so far only set upper limits, which are many orders of magnitude larger than Standard Model (SM) predictions, the motivation for more sensitive searches is stronger than ever. A new effort at FRM-II incorporating ¹²⁹Xe and ³He as a co-magnetometer can potentially improve the current limit. The noble gas mixture of ¹²⁹Xe and ³He is simultanously polarized by spin-exchange optical pumping and then transferred into a high-performance magnetically shielded room. Inside, both species can freely precess in the presence of applied magnetic and electric fields. The precession signals are detected by LTc SQUID sensors. In EDM cells with silicon electrodes we observed spin lifetimes in excess of 2500 s without and with high-voltage applied. This meets one requirement to achieve our goal of improving the EDM limit on ¹²⁹Xe by several orders of magnitude.