Visualizing brain inflammation with a shingled-leg radio-frequency head probe for 19F/1H MRI

Magnetic resonance imaging (MRI) provides the opportunity of tracking cells in vivo. Major challenges in dissecting cells from the recipient tissue and signal sensitivity constraints albeit exist. In this study, we aimed to tackle these limitations in order to study inflammation in autoimmune encephalomyelitis. We constructed a very small dual-tunable radio frequency (RF) birdcage probe tailored for ¹⁹F (fluorine) and ¹H (proton) MR mouse neuroimaging. The novel design eliminated the need for extra electrical components on the probe structure and afforded a uniform -field as well as good SNR. We employed fluorescently-tagged ¹⁹F nanoparticles and could study the dynamics of inflammatory cells between CNS and lymphatic system during development of encephalomyelitis, even within regions of the brain that are otherwise not easily visualized by conventional probes. ¹⁹F/¹H MR Neuroimaging will allow us to study the nature of immune cell infiltration during brain inflammation over an extensive period of time.

Current CONtrolled Transmit And Receive Coil Elements (CONTAR) for Parallel Acquisition and Parallel Excitation Techniques at High-Field MRI

A novel intrinsically decoupled transmit and receive radio-frequency coil element is presented for applications in parallel imaging and parallel excitation techniques in high-field magnetic resonance imaging. Decoupling is achieved by a twofold strategy: during transmission elements are driven by current sources, while during signal reception resonant elements are switched to a high input impedance preamplifier. To avoid B(0) distortions by magnetic impurities or DC currents a resonant transmission line is used to relocate electronic components from the vicinity of the imaged object. The performance of a four-element array for 3 T magnetic resonance tomograph is analyzed by means of simulation, measurements of electromagnetic fields and bench experiments. The feasibility of parallel acquisition and parallel excitation is demonstrated and compared to that of a conventional power source-driven array of equivalent geometry. Due to their intrinsic decoupling the current-controlled elements are ideal basic building blocks for multi-element transmit and receive arrays of flexible geometry.

Synthesis and chromatography of [CpRu]+-complexed bastadin precursors

The eastern and western diaryl ether portions of the macrocyclic bastadins, natural products from the marine sponge Ianthella sp., have been assembled as [CpRu]+ complexes. In an HPLC study, aminopropyl-functionalised silica was found as a very suitable stationary phase for the chromatographic separation of the different cationic ruthenium sandwich complexes. It is now possible for the first time to effectively monitor and purify [CpRu]+ complexes and to carry them through several synthetic steps.

Synthesis of the marine natural product nalpha-(4-bromopyrrolyl-2-carbonyl)-L-homoarginine, a putative biogenetic precursor of the pyrrole-imidazole alkaloids

Lysine is proposed as an alternative biosynthetic precursor of the pyrrole-imidazole alkaloids frequently found in marine sponges. As a putative key intermediate, the natural product Nalpha-(4-bromopyrrolyl-2-carbonyl)-L-homoarginine (1) from the sponge Agelas wiedenmayeri was synthesized in the solid phase starting from Fmoc/Pmc-protected L-homoarginine and in solution starting from readily available L-lysine methyl ester.

Computer-Assisted Constitutional Assignment of Large Molecules: Cocon Analysis of Ascomycin

[structure: see text] The computer-assisted constitutional assignment of ascomycin (1) is discussed. This example demonstrates that the NMR-based structure generator COCON is able to analyze data sets of organic molecules covering the full known range in size and complexity. The structural proposals of ascomycin were validated by calculating the 13C NMR chemical shifts using the computer program SpecEdit. The enhanced calculation time of COCON achieved by preorganizing the input data is also demonstrated for the data sets of aflatoxin B1 (2), 11-hydroxyrotenone (3), and haemoventosin (4).

Eleutherobin, a novel cytotoxic agent that induces tubulin polymerization, is similar to paclitaxel (Taxol)

Eleutherobin is a novel natural product isolated from a marine soft coral that is extremely potent for inducing tubulin polymerization in vitro and is cytotoxic for cancer cells with an IC50 similar to that of paclitaxel. This compound is cross-resistant along with other multidrug-resistant agents against P-glycoprotein-expressing cells and is cross-resistant with paclitaxel against a cell line that has altered tubulin. In mechanistic studies, eleutherobin shares with paclitaxel the ability to induce tubulin polymerization in vitro and is most likely cytotoxic by virtue of this mechanism. Human colon carcinoma cells exposed to eleutherobin contain multiple micronuclei and microtubule bundles, and they arrest in mitosis, depending on concentration, cell line, and length of exposure. These morphological abnormalities appearing in cultured cells are indistinguishable from those induced by paclitaxel. Electron microscopy reveals that eleutherobin induces homogeneous populations of long, rigid microtubules similar to those formed by paclitaxel. Thus, eleutherobin is a new chemotype with a mechanism of action similar to that of paclitaxel and, as such, has promising potential as a new anticancer agent.