Quantification of neurons in Alzheimer and control brains with ex vivo high resolution magic angle spinning proton magnetic resonance spectroscopy and stereology

Samples from human brains were examined with both stereologic methods for neuronal counting and high resolution magic angle spinning (HRMAS) proton magnetic resonance spectroscopy (1HMRS) for quantification of cellular metabolites. A statistically significant linear correlation between neuronal density and the concentration of N-acetylaspartate (NAA) in the superior temporal sulcus (STS) area was observed. Although NAA has been widely utilized as a neuronal marker in in vivo MRS, an emerging sub-discipline of diagnostic neuroradiology, the experimental proof of the unilateral relationship between NAA and neurons has yet to be confirmed. The observed correlation provides experimental evidence that NAA concentration is proportional to the neuronal density. Metabolite ratios measured from the STS area were compared to those from frontal association cortex for their sensitivities in differentiating Alzheimer disease brains from control brains.     

Distribution and mobility of phosphates and sodium ions in cheese by solid‐state 31P and double‐quantum filtered 23Na NMR spectroscopy

The feasibility of solid‐state magic angle spinning (MAS) ³¹P nuclear magnetic resonance (NMR) spectroscopy and ²³Na NMR spectroscopy to investigate both phosphates and Na⁺ ions distribution in semi‐hard cheeses in a non‐destructive way was studied. Two semi‐hard cheeses of known composition were made with two different salt contents. ³¹P Single‐pulse excitation and cross‐polarization MAS experiments allowed, for the first time, the identification and quantification of soluble and insoluble phosphates in the cheeses. The presence of a relatively ‘mobile’ fraction of colloidal phosphates was evidenced. The detection by ²³Na single‐quantum NMR experiments of all the sodium ions in the cheeses was validated. The presence of a fraction of ‘bound’ sodium ions was evidenced by ²³Na double‐quantum filtered NMR experiments. We demonstrated that NMR is a suitable tool to investigate both phosphates and Na⁺ ions distributions in cheeses. The impact of the sodium content on the various phosphorus forms distribution was discussed and results demonstrated that NMR would be an important tool for the cheese industry for the processes controls. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of total cholesterol in meat and poultry by gas chromatography: single-laboratory validation

The primary objective of this study was to determine the intralaboratory performance of a cholesterol determination method that combines direct saponification of a 1 g meat or poultry sample and GC quantification of liberated cholesterol without derivatization. Cholesterol was detected at 11.96 min using a GC-flame ionization detector (FID) system. With a 0.005 mg/mL 5alpha-cholestane internal standard and 0.008 to 0.020 mg/mL cholesterol standard series, the FID response was linearly correlated to standard concentrations with a coefficient of determination of 0.995 and a response factor of 0.66. The LOD and LOQ were 1.24 and 4.00 mg/100 g, respectively. Cholesterol could be analyzed within 6 days of preparation with high precision (CV of 0.92 to 2.69%) and accuracy (recovery of 93.24 to 100.56%). This simplified procedure allows for decreased errors and increased productivity, and the method proved to be reliable and able to withstand practical variation in procedural application. The method has been applied routinely with excellent precision to update data on the cholesterol content of beef, pork, and chicken in the U.S. Department of Agriculture National Nutrient Database for Standard Reference.     

Investigations into beam monitors at the AEg ̄ IS experiment

Detailed diagnostic of antiproton beams at low energies is required for essentially all experiments at the Antiproton Decelerator (AD), but will be particularly important for the future Extra Low ENergy Antiproton ring (ELENA) and its keV beam lines to the different experiments. Many monitors have been successfully developed and operated at the AD, but in particular beam profile monitoring remains a challenge. A dedicated beam instrumentation and detector test stand has recently been setup at the AE \(\bar {g}\) IS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). Located behind the actual experiment, it allows for parasitic use of the antiproton beam at different energies for testing and calibration. With the aim to explore and validate different candidate technologies for future low energy beam lines, as well as the downstream antihydrogen detector in AE \(\bar {g}\) IS, measurements have been carried out using Silicon strip and pixel detectors, a purpose-built secondary emission monitor and emulsions. Here, results from measurements and characterization of the different detector types with regard to their future use at the AD complex are presented.     

A transformed time-dependent Michaelis–Menten enzymatic reaction model and its asymptotic stability

The dynamic form of the Michaelis–Menten enzymatic reaction equations provide a time-dependent model in which a substrate $S$ reacts with an enzyme $E$ to form a complex $C$ which in turn is converted into a product $P$ and the enzyme $E$ . In the present paper, we show that this system of four nonlinear equations can be reduced to a single nonlinear differential equation, which is simpler to solve numerically than the system of four equations. Applying the Lyapunov stability theory, we prove that the non-zero equilibrium for this equation is globally asymptotically stable, and hence that the non-zero steady-state solution for the full Michaelis–Menten enzymatic reaction model is globally asymptotically stable for all values of the model parameters. As such, the steady-state solutions considered in the literature are stable. We finally discuss properties of the numerical solutions to the dynamic Michaelis–Menten enzymatic reaction model, and show that at small and large time scales the solutions may be approximated analytically.     

Structural and Conformational Analysis of 1-Butyl-3-methylimidazolium Nitrate

Journal of Chemical Crystallography - The crystal structures of two polymorphic forms of 1-butyl-3-methylimidazolium nitrate are reported. The form observed at 100 K and 200 K (Ia and Ib)...     

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-ones

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-one derivatives was the subject of investigations leading to the preparation of title compounds 11, 13, 14 and 26 . Target quinazolines 1 were synthesized in three ways; the route starting from o-vanillin via the intermediacy of 6-amino-2,3-dimethoxyacetophenone ( 19 ) was used for most of the preparative work. The unexpected formation of an acid-labile dimer of 13 was discovered and solid state ¹³C nmr was used for structural assignment. The 5-methoxy substituent in these systems shows anomalous spectral characteristics and, in one case, was cleaved in acid media to 22 .     

Photodegradation of polyethylene film

A structure occurs in radical-polymerized polyethylene which leads to formation of a triene on ultraviolet radiation. An inhibition of oxidative processes is observed while the triene or its precursor are being consumed. Subsequent formation of oxygenated products—hydroxyl, carbonyl, and carboxyl—is well behaved and arises from short wavelenght light. A crosslinking reaction is initiated by light of ～4000 Å wavelength.     

An asymmetric synthesis of indole alkaloids

Chiral formamidines derived from β-carbolines are metallated and alkylated stereoselectively opening a route to indole alkaloids and analogous compounds.