Detection of specific Bacillus anthracis spore biomarkers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was applied for the characterization of Bacillus anthracis spore biomarkers. B. anthracis spores were extracted under a simple procedure, followed by linear mode analysis, using sinapinic acid as the matrix. Several markers with a mass range of 4-7 kDa were detected in three B. anthracis strains: Vollum, Sterne and V770-NP1-R. Similar spectra were also obtained for spore extracts of two members of the B. cereus group: B. thuringiensis and B. cereus, but not for B. mycoides, B. subtilis or B. licheniformis, suggesting that these markers are specific to closely related members of the B. cereus group. When alpha-cyano-4-hydroxycinnamic acid was used as the matrix, at least four additional new markers within a mass range of 2-4 kDa could be detected in all B. anthracis spore extracts. These markers, corresponding to a molecular weight of 2528.3, 2792.4, 3077.4, and 3590.7 Da, have not been observed in extracts of the three closely related Bacillus species - B. cereus, B. thuringiensis and B. mycoides. These unique B. anthracis biomarkers, which were isotopically resolved and reproducibly detected in the highly accurate MALDI-TOFMS reflectron mode, may be useful as a basis for rapid and specific identification of B. anthracis strains.     

NMR probe for the simultaneous acquisition of multiple samples.

A dual channel probe for the simultaneous acquisition of NMR data from multiple samples has been developed. This multiplex probe consists of two noninteracting sample coils that are each capable of detecting NMR signals at the same resonant frequency with good sensitivity and resolution. 13C free induction decays for the two samples, methanol (13C, 99%) and carbon tetrachloride (13C, 99%), were acquired simultaneously at 75.44 MHz using a single transmitter pulse and separate NMR receivers. S/N measurements are comparable to those observed using single coils. No evidence of cross talk is evident in the spectra even after considerable signal averaging. The probe demonstrates the feasibility of significant parallelism in NMR, which will be of interest in situations where high throughput analysis is desired.     

Electron radiation damage in copper in the high voltage electron microscope

The various factors influencing the nucleation of radiation damage in the HVEM are reviewed. A method for obtaining quantitative information from observations is given. The effect of reirradiation at room temperature on the damage formed at elevated temperatures is shown. This effect may give experimental information concerning the strain fields surrounding large dislocation loops.     

Hyperplane Envelopes and the Clairaut Equation

The subject of envelopes has been part of differential geometry from the beginning. This paper brings a modern perspective to the classical problem of envelopes of families of affine hyperplanes. In the process, the classical results are generalized and unified.     

Untersuchung von Mehl- und Backwaren

Ohne Zusammenfassung     

Uptake and biological responses to nano-Fe versus soluble FeCl3 in excised mussel gills

Nano-Fe particle uptake was experimentally examined in vitro using excised gills and blood cells of the edible blue mussel Mytilus sp. Whole gills were exposed to both Fe₂O₃ nanoparticles and a solution of the hydrated FeCl₃ salt, for up to 12 h, and blood cells for 30 min. Equimolar Fe⁺³ in the nano- and the soluble form was estimated under the assumption of dense spherical particles accommodating the same number of Fe⁺³ as in the dissolved salt solution, namely: 1,000 μg L⁻¹ Fe₂O₃ equivalent to 100 μg L⁻¹ FeCl₃·6H₂O. Putative toxic impact of nano-Fe in gill epithelia and blood cells was assessed by an array of techniques including light- and electron microscopy, biomarkers for oxidative stress (lipid peroxidation levels), neurotoxic effects (acetylcholinesterase activity) and cytotoxicity (neutral red retention). Total and filtered fractions (20 and 200 nm, respectively) of Fe were analysed by ICP-OES. Our results provide evidence for the following: (1) much of both the soluble (95%) and the nano-Fe (90%) were removed from the water column within 12 h; (2) dissolved- and nano-Fe seemed to follow different routes of uptake within the gill epithelium; (3) both nano-Fe and soluble FeCl₃ caused similar impairment of lysosomal stability in circulating blood cells; (4) lipid peroxidation in gills exposed to the two distinct forms of Fe was increased, while acetylcholinesterase activity was unaffected. In these short-term in vitro studies, there appears to be little difference in toxic response between exposure to the Fe salt and the nano-Fe indicating that, in this case, the nanoparticles do not invoke special properties affecting biological function in gills. However, with the use of nano-Fe as a food additive, clearly longer-term in vivo studies are warranted.     

Quinol-containing ligands enable high superoxide dismutase activity by modulating coordination number,charge, oxidation states and stability of manganese complexes throughout redox cycling

Reactivity assays previously suggested that two quinol-containing MRI contrast agent sensors for H₂O₂, [Mn(H2qp1)(MeCN)]²⁺ and [Mn(H4qp2)Br₂], could also catalytically degrade superoxide. Subsequently, [Zn(H2qp1)(OTf)]⁺ was found to use the redox activity of the H2qp1 ligand to catalyze the conversion of O₂˙⁻ to O₂ and H₂O₂, raising the possibility that the organic ligand, rather than the metal, could serve as the redox partner for O₂˙⁻ in the manganese chemistry. Here, we use stopped-flow kinetics and cryospray-ionization mass spectrometry (CSI-MS) analysis of the direct reactions between the manganese-containing contrast agents and O₂˙⁻ to confirm the activity and elucidate the catalytic mechanism. The obtained data are consistent with the operation of multiple parallel catalytic cycles, with both the quinol groups and manganese cycling through different oxidation states during the reactions with superoxide. The choice of ligand impacts the overall charges of the intermediates and allows us to visualize complementary sets of intermediates within the catalytic cycles using CSI-MS. With the diquinolic H4qp2, we detect Mn(iii)-superoxo intermediates with both reduced and oxidized forms of the ligand, a Mn(iii)-hydroperoxo compound, and what is formally a Mn(iv)-oxo species with the monoquinolate/mono-para-quinone form of H4qp2. With the monoquinolic H2qp1, we observe a Mn(ii)-superoxo ↔ Mn(iii)-peroxo intermediate with the oxidized para-quinone form of the ligand. The observation of these species suggests inner-sphere mechanisms for O₂˙⁻ oxidation and reduction that include both the ligand and manganese as redox partners. The higher positive charges of the complexes with the reduced and oxidized forms of H2qp1 compared to those with related forms of H4qp2 result in higher catalytic activity (k_cat ∼ 10⁸ M⁻¹ s⁻¹ at pH 7.4) that rivals those of the most active superoxide dismutase (SOD) mimics. The manganese complex with H2qp1 is markedly more stable in water than other highly active non-porphyrin-based and even some Mn(ii) porphyrin-based SOD mimics.

Manganese complexes with polydentate quinol-containing ligands are found to catalyze the degradation of superoxide through inner-sphere mechanisms. The redox activity of the ligand stabilizes higher-valent manganese species.