Methemoglobin Is an Endogenous Toll-Like Receptor 4 Ligand—Relevance to Subarachnoid Hemorrhage

Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage (SAH), and may be responsible for important complications of SAH. Signaling by Toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NFκB) in microglia plays a critical role in neuronal damage after SAH. Three molecules derived from erythrocyte breakdown have been postulated to be endogenous TLR4 ligands: methemoglobin (metHgb), heme and hemin. However, poor water solubility of heme and hemin, and lipopolysaccharide (LPS) contamination have confounded our understanding of these molecules as endogenous TLR4 ligands. We used a 5-step process to obtain highly purified LPS-free metHgb, as confirmed by Fourier Transform Ion Cyclotron Resonance mass spectrometry and by the Limulus amebocyte lysate assay. Using this preparation, we show that metHgb is a TLR4 ligand at physiologically relevant concentrations. metHgb caused time- and dose-dependent secretion of the proinflammatory cytokine, tumor necrosis factor α (TNFα), from microglial and macrophage cell lines, with secretion inhibited by siRNA directed against TLR4, by the TLR4-specific inhibitors, Rs-LPS and TAK-242, and by anti-CD14 antibodies. Injection of purified LPS-free metHgb into the rat subarachnoid space induced microglial activation and TNFα upregulation. Together, our findings support the hypothesis that, following SAH, metHgb in the subarachnoid space can promote widespread TLR4-mediated neuroinflammation.     

Experimental Evaluation of Food-Grade Semi-Refined Carrageenan Toxicity

The safety of food additives E407 and E407a has raised concerns in the scientific community. Thus, this study aims to assess the local and systemic toxic effects of the common food additive E407a in rats orally exposed to it for two weeks. Complex evaluations of the effects of semi-refined carrageenan (E407a) on rats upon oral exposure were performed. Local effects of E407a on the intestine were analyzed using routine histological stains and CD68 immunostaining. Furthermore, circulating levels of inflammatory markers were assessed. A fluorescent probe O1O (2- (2′-OH-phenyl)-5-phenyl-1,3-oxazole) was used for evaluating the state of leukocyte cell membranes. Cell death modes of leukocytes were analyzed by flow cytometry using Annexin V and 7-aminoactinomycin D staining. Oral administration of the common food additive E407a was found to be associated with altered small and large intestinal morphology, infiltration of the lamina propria in the small intestine with macrophages (CD68⁺ cells), high systemic levels of inflammation markers, and changes in the lipid order of the phospholipid bilayer in the cell membranes of leukocytes, alongside the activation of their apoptosis. Our findings suggest that oral exposure to E407a through rats results in the development of intestinal inflammation.     

Novel Approach for the Synthesis of Chlorophosphazene Cycles with a Defined Size via Controlled Cyclization of Linear Oligodichlorophosphazenes [Cl(PCl2=N)n–PCl3]+[PCl6]−

Despite a significant number of investigations in the field of phosphazene chemistry, the formation mechanism of this class of cyclic compounds is still poorly studied. At the same time, a thorough understanding of this process is necessary, both for the direct production of phosphazene rings of a given size and for the controlled cyclization reaction when it is secondary and undesirable. We synthesized a series of short linear phosphazene oligomers with the general formula Cl[PCl2=N]n–PCl₃⁺PCl₆^– and studied their tendency to form cyclic structures under the influence of elevated temperatures or in the presence of nitrogen-containing agents, such as hexamethyldisilazane (HMDS) or ammonium chloride. It was established that linear oligophosphazenes are inert when heated in the absence of the mentioned cyclization agents, and the formation of cyclic products occurs only when these agents are involved in the process. The ability to obtain the desired size phosphazene cycle from corresponding linear chains is shown for the first time. Known obstacles, such as side interaction with the PCl₆^– counterion and a tendency of longer chains to undergo crosslinking elongation instead of cyclization are still relevant, and ways to overcome them are being discussed.     

LanGT2 Catalyzes the First Glycosylation Step during landomycin A biosynthesis

The glycosyltransferase LanGT2 is involved in the biosynthesis of the hexasaccharide side chain of the angucyclic antibiotic landomycin A. Its function was elucidated by targeted gene inactivation of lanGT2. The main metabolite of the obtained mutant was identified as tetrangulol (4), the progenitor of the landomycin aglycon (7). The lack of the sugar side chain indicates that LanGT2 catalyzes the priming glycosyl transfer in the hexasaccharide biosynthesis: the attachment of a D-olivose to O-8 of the polyketide backbone. Heterologous expression of urdGT2 from S. fradiae Tü2717 in this mutant resulted in the production of a novel C-glycosylated angucycline (6).     

The use of hybrid anaerobic solid–liquid (HASL) system for the treatment of lipid‐containing food waste

The hybrid anaerobic solid–liquid (HASL) system was a modified two‐phase anaerobic digester developed for bioconversion of food waste. The aim of this study was to estimate the feasibility of the HASL system for the treatment of food waste with a high content of lipids. The presence of lipids in food waste increased the energy value of nutrients but could inhibit growth of methanogens. The positive effect of lipids on the performance of anaerobic digestion dominated when the contents of lipids were in the range from 20 to 30% of total solids of food waste. Lipid contents of 40% diminished the production of volatile fatty acids in the acidogenic reactor as well as biogas production and the concentration of total bacteria and methanogens in the methanogenic reactor. Therefore, the HASL system can be used for the treatment of lipid‐containing food wastes if the lipid content is below 40% of total solids. Copyright © 2005 Society of Chemical Industry     

Structure,magnetic and magnetocaloric properties of RE11Ge8In2 (RE = Gd–Tm)

A new tetragonal Gd₁₁Ge₈In₂ phase has been obtained by arc-melting and annealing at 800 °C. The structure has been determined and refined from single crystal X-ray diffraction data in the I4/mmm space group with a = 11.2091(6) and c = 16.3994(9) Å. Phases with the RE₁₁Ge₈In₂ (RE = Gd–Tm) composition were subsequently synthesized and their structures were refined using X-ray powder diffraction methods. Magnetic measurements carried out on RE₁₁Ge₈In₂ (RE = Gd–Tm) indicated a ferromagnetic ordering in all phases. The magnetocaloric effect in terms of the magnetic entropy change, ΔS_mag, was evaluated for the Gd-, Tb- and Tm-containing samples, and the largest |ΔS_mag| value of 10.6 J/kg K was obtained for Tm₁₁Ge₈In₂.     

Microfluidic characterization and continuous separation of cells and particles using conducting poly(dimethyl siloxane) electrode induced alternating current-dielectrophoresis

This paper presents a poly(dimethyl siloxane) (PDMS) polymer microfluidic device using alternating current (ac) dielectrophoresis (DEP) for separating live cells from interfering particles of similar sizes by their polarizabilities under continuous flow and for characterizing DEP behaviors of cells in stagnant flow. The ac-DEP force is generated by three-dimensional (3D) conducting PDMS composite electrodes fabricated on a sidewall of the device main channel. Such 3D PDMS composite electrodes are made by dispersing microsized silver (Ag) fillers into PDMS gel. The sidewall AgPDMS electrodes can generate a 3D electric field that uniformly distributes throughout the channel height and varies along the channel lateral direction, thereby producing stronger lateral DEP effects over the entire channel. This allows not only easy observation of cell/particle lateral motion but also using the lateral DEP force for manipulation of cells/particles. The former feature is used to characterize the frequency-dependent DEP behaviors of Saccharomyces cerevisiae (yeast) and Escherichia coli (bacteria). The latter is utilized for continuous separation of live yeast and bacterial cells from similar-size latex particles as well as live yeast cells from dead yeast cells. The separation efficiency of 97% is achieved in all cases. The demonstration of these functions shows promising applications of the microfluidic device.     

Recent development and new ideas in the field of dispersive multilayer optics

A dispersive-mirror-based laser permits a dramatic simplification of high-power femtosecond and attosecond systems and affords promise for their further development toward shorter pulse durations, higher peak powers, and higher average powers with user-friendly systems. The result of the continuous development of dispersive mirrors permits pulse compression down to almost single cycle pulses of 3?fs duration. These design approaches together with the existing modern deposition technology pave the way for the manufacture of dielectric multilayer coatings able to compress pulses of tens of picoseconds duration down to a few femtoseconds.     

Analysis of dynamic matching networks for the ICRF system at ASDEX Upgrade

The ICRF (Ion Cyclotron Range of Frequencies) system, used to heat the plasma of ASDEX Upgrade, consists of RF generators, 3 dB hybrids, coaxial transmission lines, matching networks and inductive loop antennas. The maximum power achievable by the generator strongly depends on the amplitude and phase of the reflection coefficient. Hence, matching of the antenna input impedance to the generator output impedance is essential for the ICRF heating system. The coupling between the ICRF antennas and the plasma is subject to relatively fast variations (few ms). The changes are caused by the modification of plasma edge conditions, such as L–H mode transitions, gas puffing or ELMs (Edge Localized Modes). These variations change the impedance of the ICRF antennas. For optimal operation of the ICRF system, a continuous, and fast matching is therefore preferable. A MATLAB^® based simulation tool has been developed to analyse matching networks for the ICRF system at ASDEX Upgrade. The program is highly flexible, and can solve the matching calculations for different conditions and configurations of the system. The results are presented in a Smith chart.