An alternative paper based tissue washing method for mass spectrometry imaging: localized washing and fragile tissue analysis

Surface treatment of biological tissue sections improves detection of peptides and proteins for mass spectrometry imaging. However, liquid surface treatments can result in diffusion of surface analytes and fragile tissue sections can be easily damaged by typical washing solvents. Here, we present a new surface washing procedure for mass spectrometry imaging. This procedure uses solvent wetted fiber-free paper to enable local washing of tissue sections for mass spectrometry imaging and tissue profiling experiments. In addition, the method allows fragile tissues that cannot be treated by conventional washing techniques to be analyzed by mass spectrometry imaging.     

Prospective study of a Bothrops jararacussu venom batch (Bj2015) – phospholipase A2 activity,immunogenicity, neurotoxicity,and myotoxicity parameters

Bothrops jararacussu venom’s (Bj2015) batch was biomonitored quarterly for one year to assess phospholipase A₂ (PLA₂) activity, immunogenicity, neurotoxicity, and myotoxicity. In silico models were applied to evaluate losses using decay model and recoveries by predictive trend analysis. Mice were immunized with Bj2015. Antibodies were detected by double-immunodiffusion and total protein and albumin were measured. Neuromuscular blockade-induced by 40 μg mL^?1 venom solution was carried out using mouse nerve phrenic-diaphragm preparation. Resulting muscles were submitted to light microscopy to evaluate the myotoxicity. PLA₂ activity of 0.1 mg mL^?1 Bj2015 was measured using 4-nitro-3-(octanoyloxy)benzoic acid as substrate. Over time, greater losses occurred in neurotoxicity than PLA₂, but not in myotoxicity and immunogenicity. Concluding, the neurotoxicity decrease can be related to enzymatic losses, including PLA₂. Depending on the purpose of use, the collected venom responds on a long time, avoiding unnecessary new collections, improving life quality of animals in captivity and increasing their longevity.     

Interface of covalently bonded phospholipids with a phosphorylcholine head: characterization, protein nonadsorption, and further functionalization

Surface anchored poly(methylhydrosiloxane) (PMHS) thin films on oxidized silicon wafers or glass substrates were functionalized via the SiH hydrosilylation reaction with the internal double bonds of 1,2-dilinoleoyl-sn-glycero-3-phosphorylcholine (18:2 Cis). The surface was characterized by X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, and scanning electron microscopy. These studies showed that the PMHS top layer could be efficiently modified resulting in an interfacial high density of phospholipids. Grafted phospholipids made the initially hydrophobic surface (θ = 106°) very hydrophilic and repellent toward avidin, bovine serum albumin, bovine fibrinogen, lysozyme, and α-chymotrypsin adsorption in phosphate saline buffer pH 7.4. The surface may constitute a new background-stable support with increased biocompatibility. Further possibilities of functionalization on the surface remain available owing to the formation of interfacial SiOH groups by Karstedt-catalyzed side reactions of SiH groups with water. The presence of interfacial SiOH groups was shown by zeta potential measurements. The reactivity and surface density of SiOH groups were checked by fluorescence after reaction of a monoethoxy silane coupling agent bearing Alexa as fluorescent probe.     

Formation and cleavage of C-H, C-C, and C-O bonds of ortho-methyl-substituted anisoles by late transition metals

2,6-Dimethyl-substituted anisoles can be converted into the corresponding 2-ethyl-6-methylphenols in a several-step reaction mediated by a TpMe2Ir(III) complex; use of the 13C-enriched anisoles, ArO13CH3, shows that the 13C label distributes across the two ethyl sites with a preference for the terminal position.     

Corrigendum to “Computing of the number of right coideal subalgebras of Uq(so2n+1)” [J. Algebra 341 (1) (2011) 279–296]

Adjoint functors and projectivization in representation theory of partially ordered sets are used to generalize the algorithms of differentiation by a maximal and by a minimal point. Conceptual explanations are given for the combinatorial construction of the derived set and for the differentiation functor.     

Total synthesis of biseokeaniamides A–C and late-stage electrochemically-enabled peptide analogue synthesis

The first total synthesis of cytotoxic cyanobacterial peptide natural products biseokeaniamides A–C is reported employing a robust solid-phase approach to peptide backbone construction followed by coupling of a key thiazole building block. To rapidly access natural product analogues, we have optimized an operationally simple electrochemical oxidative decarboxylation–nucleophilic addition pathway which exploits the reactivity of native C-terminal peptide carboxylates and abrogates the need for building block syntheses. Electrochemically-generated N,O-acetal intermediates are engaged with electron-rich aromatics and organometallic reagents to forge modified amino acids and peptides. The value of this late-stage modification method is highlighted by the expedient and divergent production of bioactive peptide analogues, including compounds which exhibit enhanced cytotoxicity relative to the biseokeaniamide natural products.

A late-stage electrochemical decarboxylation enables rapid access to structural analogues of biseokeaniamides A–C, cytotoxic lipopeptide natural products.     

Synthesis of aluminosilicates under high pressure and using sulfur as directing agent

Two aluminosilicates were prepared under hydrothermal conditions. Silica, sodium aluminate, sodium sulfide and sulfur were used as raw materials. Starting with similar reacting mixtures, analcime (zeolite, Na(Si₂Al)O₆·H₂O) and beidellite (clay, Na_0.3Al₂(Si, Al)₄O₁₀(OH)₂·2H₂O) were synthesized by varying pressures, 2 kbar and 1 kbar, respectively. Sulfur was present in both aluminosilicate surfaces, which confer to them particular adsorption properties. Additionally, water adsorption isotherms, under dynamical conditions, were obtained. Fractal dimension values and SEM micrographs reveal very different textural and morphological properties of the two prepared aluminosilicates     

A torsion-based solution to the hyperbolic regime of the $$J_2$$ -problem

A popular intermediary in the theory of artificial satellites is obtained after the elimination of parallactic terms from the \(J_2\)-problem Hamiltonian. The resulting quasi-Keplerian system is in turn converted into the Kepler problem by a torsion. When this reduction process is applied to unbounded orbits, the solution is made of Keplerian hyperbolae. For this last case, we show that the torsion-based solution provides an effective alternative to the Keplerian approximation customarily used in flyby computations. Also, we check that the extension of the torsion-based solution to higher orders of the oblateness coefficient yields the expected convergence of asymptotic solutions to the true orbit.