Luisa Schenetti

1H HR-MAS and genomic analysis of human tumor biopsies discriminate between high and low grade astrocytomas

We investigate the profile of choline metabolites and the expression of the genes of the Kennedy pathway in biopsies of human gliomas (n = 23) using 1H High Resolution Magic Angle Spinning (HR‐MAS, 11.7 Tesla, 277 K, 4000 Hz) and individual genetic assays. 1H HR‐MAS spectra allowed the resolution and relative quantification by the LCModel of the resonances from choline (Cho), phosphocholine (PC) and glycerophosphorylcholine (GPC), the three main components of the combined tCho peak observed in gliomas by in vivo 1H NMR spectroscopy. All glioma biopsies depicted a prominent tCho peak. However, the relative contributions of Cho, PC, and GPC to tCho were different for low and high grade gliomas. Whereas GPC is the main component in low grade gliomas, the high grade gliomas show a dominant contribution of PC. This circumstance allowed the discrimination of high and low grade gliomas by 1H HR‐MAS, a result that could not be obtained using the tCho/Cr ratio commonly used by in vivo 1H NMR spectroscopy. The expression of the genes involved in choline metabolism has been investigated in the same biopsies. High grade gliomas depict an upregulation of the β gene of choline kinase and phospholipase C, as well as a downregulation of the cytidyltransferase B gene, the balance of these being consistent with the accumulation of PC. In the low grade gliomas, phospholipase A1 and lysophospholypase are upregulated and phospholipase D is downregulated, supporting the accumulation of GPC. The present findings offer a promising procedure that will potentially help to accurately grade glioma tumors using 1H HR‐MAS, providing in addition the genetic background for the alterations of choline metabolism observed in high and low grade gliomas. Copyright

Discrimination of Healthy and Neoplastic Human Colon Tissues by ex Vivo HR-MAS NMR Spectroscopy and Chemometric Analyses

The metabolic profile of human healthy and neoplastic colorectal tissues was obtained using ex vivo High-Resolution Magic Angle Spinning (HR-MAS) NMR spectroscopy. Principal Components Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) were applied to NMR data in order to highlight the biochemical differences between healthy and neoplastic colorectal tissues. The synergic combination of ex vivo HR-MAS NMR spectroscopy with Multivariate Data Analysis enables discrimination between healthy and tumoral colorectal tissues and identification of the increase of taurine, acetate, lactate, and lipids, and the decrease of polyols and sugars as tumoral characteristics. Moreover, it was found that macroscopically/histologically normal colorectal tissues, collected at least 15 cm from the adenocarcinoma, are characterized by a metabolic pattern quite similar to that typical of tumoral lesions. It was shown that ex vivo HR-MAS NMR spectroscopy, performed on intact specimens, may be of great potentiality in the clinical evaluation of human neoplastic colorectal tissues and that the biochemical data represent the molecular basis for an accurate and noninvasive clinical applications of in vivo NMR spectroscopy.

Electrostatic layer-by-layer construction and characterization of photoelectrochemical solar cells based on water soluble polythiophenes and carbon nanotubes

Positively and negatively charged functionalized polythiophenes and single walled carbon nanotubes were sequentially adsorbed on indium tin oxide electrodes by electrostatic and van der Waals interactions using the layer-by-layer deposition method. The resulting donor/acceptor photoelectrodes were tested as photoelectrochemical cells. Upon illumination, monochromatic incident photoconversion efficiencies of 8.2 and 4.3% were determined for eight stacks of single walled carbon nanotubes with ammonium and sulfonate polythiophene derivatives, respectively.

Gas sensing measurements and analysis of the optical properties of poly[3-(butylthio)thiophene] Langmuir–Blodgett films

Abstract Films of poly[(3-butylthio)thiophene] were prepared via Langmuir–Blodgett (LB) deposition and casting techniques for applications in gas sensor devices. A description of the preparation of the sensing layer is given for both methods: the LB deposition of the polymer in mixture with arachidic acid and the solvent casting by using directly a solution of the polymer in chloroform. In both cases, alumina substrates equipped with gold interdigitated electrodes have been used. In particular, the samples so prepared show variation in the electrical conductivity when exposed to NO2-oxidising or NH3-reducing agents at a working temperature of about 100°C. The refractive index n and the extinction coefficient k at normal incidence have been determined in the 400–800 nm spectral range and an energy gap (highest occupied-molecular-orbital or conduction band (HOMO)–lowest unoccupied molecular-orbital or valence band (LUMO) separation) of about 1.9 eV has been estimated.

Synthesis of 5-methoxylated 3-pyrrolin-2-ones via the rearrangement of chlorinated pyrrolidin-2-ones

The reaction of N-substituted 4-methyl-2-pyrrolidinones or 4-diethoxyphosphoryl analogues, carrying at least two chlorine atoms between the C(3) and C(6) carbons, with alkaline methoxide in methanol afforded the corresponding 5-methoxylated 3-pyrrolin-2-ones, useful adducts for the preparation of agrochemicals or medicinal compounds.

Synthesis and characterization of poly[3-(butylthio)thiophene]: a regioregular head-to-tail polymer

Poly[3-(butylthio)thiophene] was obtained from 2,5-dibromo-3-(butylthio)thiophene according to the method of Kobayashi. The polymer was characterized as having regioregular head-to-tail (HT) connections with significant extended conjugation length and optical properties, such as solvatochromism and photoluminescence. The polymer is soluble in common organic solvents and can easily form films.

Biochemical Alterations from Normal Mucosa to Gastric Cancer by Ex vivo Magnetic Resonance Spectroscopy

Background and Aims: The metabolic profile and morphologic aspects of normal and pathologic human gastric mucosa were studied. The aim of the present research was the application of ex vivo high-resolution magic angle spinning magnetic resonance spectroscopy (HR-MAS MRS) to the human gastric tissue to get information on the molecular steps involved in gastric carcinogenesis and the identification of biochemical markers useful for the development of in vivo MRS methodologies to diagnose gastric pathologies in clinical situations. Methods: Twelve normal subjects, five with autoimmune atrophic gastritis, five with Helicobacter pylori infection, and five with adenocarcinoma were examined. Ten biopsies were taken during endoscopy from each patient. Specimens from carcinoma were also obtained during gastrectomy. Of the 10 biopsies, 4 were used for histologic evaluation, 4 were fixed in glutaraldehyde and processed for transmission and scanning electron microscopy, and 2 were immersed in liquid nitrogen and stored at −85°C for monodimensional and bidimensional ex vivo HR-MAS MRS analysis. Results: Ex vivo HR-MAS MRS identified glycine, alanine, free choline, and triglycerides as possible molecular markers related to the human gastric mucosa differentiation toward preneoplastic and neoplastic conditions. Ultrastructural studies of autoimmune atrophic gastritis and gastric adenocarcinoma revealed lipid accumulations intracellularly and extracellularly associated with a severe prenecrotic hypoxia and mitochondria degeneration. Conclusions: This is the first report of synergic applications of ex vivo HR-MAS MRS and electron microscopy in studying the human gastric mucosa differentiation. This research provides useful information about some molecular steps involved in gastric carcinogenesis. The biochemical data obtained on gastric pathologic tissue could represent the basis for clinical applications of in vivo MRS. (Cancer Epidemiol Biomarkers Prev 2008;17(6):1386–95)

STABILITY STUDIES OF CHONDROITIN SULFATE

The stability of chondroitin sulfate (CS) was studied under acidic, neutral and basic conditions at 30 and 60 degrees C. CS is remarkably stable under neutral conditions at low temperature, while it degrades at 60 degrees C producing low-molecular-mass fragments and desulfated products. This decomposition process begins at ca. 500-600 h and is consistent with an acid-catalyzed hydrolysis of glycosidic linkages caused by a drop in pH resulting from acidic products. Under basic conditions, a breakdown of glycosidic linkages causes a decrease in molecular mass due to the beta-elimination reaction, confirmed by a strong increase of absorbance at 232 nm and 1H NMR. Virtually no loss of O-sulfate groups can be detected in the base-treated CS. Under acidic conditions, the molecular mass decreases probably through hydrolysis of polysaccharidic linkages resulting in an increased number of reducing end groups. Little or no beta-elimination occurs. A loss of O-sulfate groups was detected, producing desulfated derivatives.

Citron and lemon under the lens of HR-MAS NMR spectroscopy.

High Resolution Magic Angle Spinning (HR-MAS) is an NMR technique that can be applied to semi-solid samples. Flavedo, albedo, pulp, seeds, and oil gland content of lemon and citron were studied through HR-MAS NMR spectroscopy, which was used directly on intact tissue specimens without any physicochemical manipulation. HR-MAS NMR proved to be a very suitable technique for detecting terpenes, sugars, organic acids, aminoacids and osmolites. It is valuable in observing changes in sugars, principal organic acids (mainly citric and malic) and ethanol contents of pulp specimens and this strongly point to its use to follow fruit ripening, or commercial assessment of fruit maturity. HR-MAS NMR was also used to derive the molar percentage of fatty acid components of lipids in seeds, which can change depending on the Citrus species and varieties. Finally, this technique was employed to elucidate the metabolic profile of mold flavedo.

Synthesis and electrochemical characterisation of novel sonogel–carbon–polythiophene microstructured electrodes

Abstract A sonogel–carbon–polythiophene microstructured electrode has been synthesised via sonocatalytic procedure. The composite material was characterised by cyclic voltammetry, atomic force microscopy and optical microscopy. A comparison with a similar polythiophene directly cast on a platinum electrode has been made. In contrast with the degrading behaviour (overoxidation) observed at sufficiently positive potentials for alkylsulphanyl substituted polythiophenes cast on the electrode surface, the entrapment of the polymer inside a composite material drastically enhances the stability of the redox-active phase towards irreversible oxidation. In addition, the sonogel–carbon–polythiophene composite represents a good approach to test and, possibly, exploit the electrochemical properties of the polymer which, due to its complete insolubility in the common organic solvents, cannot be adequately cast on an electrode surface or electrosynthesised.