Detection of a stable nitroxide during chemical depolymerization of heparin

The use of low-molecular-weight heparins (LMWHs) has become common, since compared to unfractionated heparin (UFH), they have a much longer plasma half-life and lower incidence of side effects. LMWHs are derived from the depolymerization of UFH, obtained either chemically, physically or enzymatically. We employed electron spin resonance (ESR) spectroscopy to study the depolymerization of UFH by copper in the presence of hydrogen peroxide. A stable nitroxide radical was detected. This could be generated by the hydroxyl radical attack either to the N-SO⁻₃ group or to free amino groups present in the UFH preparation.     

Peroxynitrite decomposition catalyst prevents apoptotic cell death in a human astrocytoma cell line incubated with supernatants of HIV-infected macrophages

Background  

Oxidative stress has shown to contribute in the mechanisms underlying apoptotic cell death occuring in AIDS-dementia complex. Here we investigated the role of peroxynitrite in apoptosis occurring in astroglial cells incubated with supernatants of HIV-infected human primary macrophages (M/M).     

Investigation of unburned carbon particles in fly ash by means of laser light scattering

A new optical method to determine the percentage of unburned carbon particles in fly ash from combustion of pulverized coal has been developed. The technique exploits the different properties of particles of ash and coal in the elastic scattering of polarized light.     

Potentially important nighttime heterogeneous chemistry: NO3 with aldehydes and N2O5 with alcohols

We report the first measurements of the reactive uptake of NO(3) with condensed-phase aldehydes. Specifically, we studied NO(3) uptake on solid tridecanal and the uptake on liquid binary mixtures containing tridecanal and saturated organic molecules (diethyl sebacate, dioctyl sebacate, and squalane) which we call matrix molecules. Uptake on the solid was shown to be efficient, where γ = (1.6 ± 0.8) × 10(-2). For liquid binary mixtures the reactivity of aldehyde depended on the matrix molecule. Assuming a bulk reaction, H(matrix)√(D(matrix)k(2°,aldehyde)) varied by a factor of 2.6, and assuming a surface reaction H(matrix)(S)K(matrix)(S)k(2°,aldehyde)(S) varied by a factor of 2.9, where H(matrix)√(D(matrix)k(2°,aldehyde)) and H(matrix)(S)K(matrix)(S)k(2°,aldehyde)(S) are constants extracted from the data using the resistor model. By assuming either a bulk or surface reaction, the atmospheric lifetimes for aldehydes were estimated to range from 1.9-7.5 h. We also carried out detailed studies of N(2)O(5) uptake kinetics on alcohols. We show that uptake coefficients of N(2)O(5) for five different organics at 293 K varied by more than 2 orders of magnitude, ranging from 3 × 10(-4) to 1.8 × 10(-2). We show that the uptake coefficients correlate with √(D(alcohol)(OH concentration)) but more work is needed with other alcohols to completely understand the dependence. Using this kinetic data we show that the atmospheric lifetime of alcohols with respect to N(2)O(5) heterogeneous chemistry can vary from 0.6-130 h, depending on the physical and chemical properties of the organic liquid.     

Electrocortical effects of MDMA are potentiated by acoustic stimulation in rats

Background  

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known for its toxicological, psychopathological and abuse potential. Some environmental conditions, e.g. acoustic stimulation typical of the "rave scene" can influence the toxicity of this drug.     

Development and validation of a liquid chromatography–tandem mass spectrometry method for the simultaneous analysis of androgens,estrogens, glucocorticoids and progestagens in human serum

We present a liquid chromatography tandem mass spectrometry method for the simultaneous analysis of 16 endogenous steroids (androgens, estrogens, glucocorticoids and progestogens) in human serum. Samples (250 μl of matrix) were extracted with t-butylmethyl ether prior to LC–MS/MS analysis. The chromatographic separation was achieved on a reversed-phase column using a methanol–water gradient. The HPLC was coupled to a triple quadrupole mass spectrometer equipped with an electrospray ionization source with acquisition in multiple reaction monitoring mode. The method was validated using surrogate matrices and human serum samples. The specificity of the method was confirmed for all of the considered steroids; linearity was also assessed (R² > 0.99, lack-of-fit test) in the ranges of concentrations investigated. The lower limits of quantification were in the range 10–400 pg/ml depending on the target steroid. Accuracy was in the range 85–115% for all target steroids except for the lower limit of quantitation levels where it was 80–120%. The extraction recovery was always >65%. No significant matrix effects were observed. To test the reliability of the method, the analysis of serum samples collected from 10 healthy subjects (5 M/5F) was performed. The present method can be used to identify the trajectories of deviation from the concentration normality ranges applied to disorders of the gonadal and adrenal axes.     

Molecular modelling and enzymatic studies of acetylcholinesterase and butyrylcholinesterase recognition with paraquat and related compounds

The potent herbicide paraquat and three other analogues MPP+, MPDP+ and MPTP have a known toxicological profile linked to the ability to damage dopaminergic neurons. Other biological effects were recently addressed to this class of compounds, including the ability to interact with enzymatic targets involved in the Central Nervous System, such as the acetylcholinesterase (AChE) and the butyrylcholinesterase (BuChE). A combined molecular modelling and enzymatic study focusing onto their interaction against the AChE and BuChE is reported. The former study was performed by docking techniques using target known co-crystallographic models. The latter study was carried out by the widely adopted Ellman's method. In both studies the anti-Alzheimer FDA approved drug tacrine was used as reference inhibitor. Our results indicate that paraquat, MPTP, MPDP+ and MPP+ recognize both enzymatic cleft in a similar fashion compared to the reference inhibitor. A structure-activity correlation was found with the net charge of the ligands, indicating a major role of the electrostatic term in the recognition and inhibition of these compounds. Our data completed their enzymatic profile, added new information on the molecular mechanisms underlying their neurotoxicity useful for the rational design of new cholinesterase inhibitors.     

High-precision determination of the 13CO2/12CO2 isotope ratio using a portable 2.008-μm diode-laser spectrometer

A compact and portable diode-laser spectrometer is developed for high-precision measurements of the ¹³CO₂/¹²CO₂ isotope ratio. Ro-vibrational transitions belonging to different combination bands, around 2.008 m, are detected for the two isotopomers, using wavelength-modulation spectroscopy with first-harmonic detection. The determination of the isotope ratio is performed through a comparison between the spectra, simultaneously acquired in two different multiple-reflection cells designed to contain the sample and reference gases. The reproducibility of our method is extensively investigated over different time scales. In particular, the short-term precision of the isotope ratio determination is found to be 0.03%. We discuss the presence of possible systematic shifts in the -v alue and optimise the operating conditions to ensure accuracy within the precision level. A possible use for in-situ measurements in volcanic gases is also discussed. PACS 42.62.Fi; 42.55.Px; 33.20.Ea     

Toward an optimum use of the optical channel capacity

In recent decades, in addition to long-haul, high-capacity links, research activity in optical fiber communication systems has addressed possible advantageous applications in distribution networks, local and metropolitan area networks, CATV backbones and distribution, and high-speed computer networks. As a consequence, new possibilities in optical transmission systems have been explored to face the new requirements in terms of capacity, spectral efficiency, and receiver sensitivity. Among the possible solutions capable to exploit effectively the potentials offered by the optical channel, novel multilevel modulation formats have been proposed for future communication environment. This paper reviews multilevel modulation techniques for optical transmission: a comparative analysis is performed between conventional modulations, such as N-PSK and N-QAM, and new modulation/demodulation techniques, such as N-4QSK, N-SPSK, and PM-DD, taking into account both system performance and technological constraints.     

Protein expression patterns associated with advanced stage ovarian cancer

This is a comparative proteomic study on biopsies from patients with ovarian cancer to identify potential diagnostic/prognostic biomarkers in both healthy and tumor tissue, interstitial fluid (normal interstitial fluid and tumoral interstitial fluid and peritoneal effusion. Protein expression/identification was evaluated by 2-DE and MS analysis: six proteins showed differential expression in tumoral interstitial fluid and tumor tissue compared to normal interstitial fluid and healthy tissue: five were found to be downregulated and identified as galectin 3, glutathione S-transferase A-2, retinol binding protein 1, phosphatidylethanolamine-binding protein and annexin 5, while the calgranulin, was significantly upregulated in all pathological samples, including the ascitic fluid. Validation of S100A8 overexpression in carcinoma tissue was obtained by immunohistochemistry. To our knowledge, this is the first study to report an over-expression of calgranulin by 2-DE associated with MS/MS analysis on surgical biopsy. The reduced expression of galectin 3 and retinol binding protein 1 in cystic fluid and serum of patients with early stage disease is confirmed in this study. The results highlight alterations in proteins that control cell-cycle progression and apoptosis, as well as factors that modulate the activity of signal transduction pathways. Moreover, this study suggests that calgranulin expression may be used as a diagnostic and/or prognostic biomarker.