S. Materazzi

Applications of evolved gas analysis. Part 2: EGA by mass spectrometry

The analytical applications of the evolved gas analysis (EGA) performed by mass spectrometry, for the period extending from 2001 to 2004, are collected in this review. By this technique, the nature of volatile products released by a substance subjected to a controlled temperature program is on-line determined, with the possibility to prove a supposed reaction, either under isothermal or under heating conditions.

Polypyrrole-polysaccharide thin films characteristics: electrosynthesis and biological properties.

Polypyrrole-polysaccharide thin films were electropolymerized from starting solutions containing pyrrole and a polysaccharide, namely, heparin, chondroitin-4-sulphate or hyaluronic acid. The synthesized samples showed good chemical and physicochemical properties determined by the synthesis parameters such as the current density and time. For instance, the sample morphology was strictly correlated to the current density as follows: a smooth surface morphology was observed when the current density was in the range of 100-700 microA/cm(2), whereas high current (I > 1.0 mA/cm(2)) or longer time (synthesis charge > 100 mC/cm(2)) led to rough surfaces. The presence of polysaccharide within the polymeric matrix assured proper hydrophilicity to the samples. The optimized surface chemistry due to the presence of a polysaccharide and the controllable morphology allowed positive cell/substrate interactions and these are proved by cellular tests using MC3T3-E1 osteoblast cultures.

Thermogravimetry – Infrared Spectroscopy (TG-FTIR) Coupled Analysis

ABSTRACT In recent years, coupled or hyphenated techniques have become popular, and have been successfully applied to the solution of many analytical problems. HPLC-MS, tandem MS-MS, GC-FTIR, TLC-FID, GC-MS, etc. are but a few of the familiar abbreviations used for these one step, “double analysis” techniques. The coupling of thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) is a good practical example (TG-FTIR) of such an instrumental approach for solving specific analytical problems. This hyphenated technique provides a quantitative assessment of the process via the TG curve (the thermogram), and an identification of the decomposition products from the IR spectra of the evolved gases. The gases are transferred from the TGA instrument by means of a heated transfer-line to avoid the possibility of condensation. With such a combination, the sample may be introduced into the TGA instrument without any form of chemical or physical modification. Applying the sequential FTIR a...

Involvement of p53 in Phthalate Effects on Mouse and Rat Osteoblasts

The role of two estrogen‐mimicking compounds in regulating osteoblast activities were examined. Previously, our attention was focused on benzyl butyl phthalate (BBP) and di‐n‐butyl phthalate (DBP) since previous works showed that they enter the cytoplasm, bioaccumulate, modify actin cytoarchitecture and exert mitogenic effects involving microfilament disruption, and nuclear actin and lamin A regulation in Py1a rat osteoblasts. In this study we showed that BBP and DBP cause DNA base lesions both in MT3T3‐E1 osteoblasts and in mouse primary calvarial osteoblasts (COBs). In addition, treatment with the above effectors caused an increase of p53 and phospho‐p53 (ser‐15 and ser‐20) as well as an increase of apoptotic proteins with consequent decrease of cell viability. Moreover, treatment with phthalates did not modified p53 and phospho‐p53 expression in Py1a rat osteoblasts. It is of relevance that in p53 knockdown mouse osteoblasts a proliferative effect of phthalates, similar to that observed in rat Py1a osteoblasts, was found. In conclusion, our data demonstrated that phthalates induce osteoblast apoptosis, which is, at least in part, mediated by p53 activation, suggesting that the proliferative effects could be due to p53 missing activation or p53 mutation. J. Cell. Biochem. 107: 316–327, 2009.

Prostaglandins differently regulate FGF-2 and FGF receptor expression and induce nuclear translocation in osteoblasts via MAPK kinase

We have previously reported that prostaglandin F2α (PGF2α) and its selective agonist fluprostenol increase basic fibroblast growth factor (FGF-2) mRNA and protein production in osteoblastic Py1a cells. The present report extends our previous studies by showing that Py1a cells express FGF receptor-2 (FGFR2) and that treatment with PGF2α or fluprostenol decreases FGFR2 mRNA. We have used confocal and electron microscopy to show that, under PGF2α stimulation, FGF-2 and FGFR2 proteins accumulate near the nuclear envelope and colocalize in the nucleus of Py1a cells. Pre-treatment with cycloheximide blocks nuclear labelling for FGF-2 in response to PGF2α. Treatment with SU5402 does not block prostaglandin-mediated nuclear internalization of FGF-2 or FGFR2. Various effectors have been used to investigate the signal transduction pathway. In particular, pre-treatment with phorbol 12-myristate 13-acetate (PMA) prevents the nuclear accumulation of FGF-2 and FGFR2 in response to PGF2α. Similar results are obtained by pre-treatment with the protein kinase C (PKC) inhibitor H-7. In addition, cells treated with PGF2α exhibit increased nuclear labelling for the mitogen-activated protein kinase (MAPK), p44/ERK2. Pre-treatment with PMA blocks prostaglandin-induced ERK2 nuclear labelling, as confirmed by Western blot analysis. We conclude that PGF2α stimulates nuclear translocation of FGF-2 and FGFR2 by a PKC-dependent pathway; we also suggest an involvement of MAPK/ERK2 in this process.

Mass Spectrometry Coupled to Thermogravimetry (TG-MS) for Evolved Gas Characterization: A Review.

INTRODUCTION Combining thermal analysis (TA) with gas-analykal techniques significantly enhances the possibilities for correctly interpreting the mechanism of thermally induced reactions, which involve the formation of gaseous species. Several techniques can be used for evolved gas analysis (EGA), ranging from simple, non-specific detection to the more elaborate multidimensional/multifunctional methods, such as gas chromatography (GC), infrared spectroscopy (IR) or mass spectrometry (MS), for gas detection and analysis [1]. While the GC methods were used as early as the 1960s [2], EGA by FTIR was described much later and was used for the analysis of pyrolytic and combustion products. Presently, there are several commercial FTIR systems available that can be coupled to a thermogravimetric analyzer (TGA), and a broad range of applications have been investigated by this important hyphenated technique [3].

Applications of evolved gas analysis Part 1: EGA by infrared spectroscopy

The analytical applications of the evolved gas analysis (EGA) performed by infrared spectroscopy, for the period extending from 2001 to 2004, are collected in this review. By this technique, the nature of volatile products released by a substance subjected to a controlled temperature program are on-line determined, with the possibility to prove a supposed reaction, either under isothermal or under heating conditions.

Thermodynamic data for Pb2+ and Zn2+ sequestration by biologically important S-donor ligands, at different temperatures and ionic strengths

Thermodynamic parameters for the interactions of cysteine (cys) and penicillamine (psh) with Pb(II) and glutathione (gsh) with Pb(II) and Zn(II) were determined in NaNO3 or NaCl aqueous solution by potentiometry, at different ionic strengths (0 < I ≤ 1 mol L−1) and temperatures (15 ≤ t ≤ 45 °C). For Pb2+ systems, the formation of PbL, PbLH, PbLH2 and PbL2 species was found, together with PbLOH for cys and psh, and PbL2H and PbL2H2 for gsh. The speciation models for Pb2+–psh and –gsh systems were confirmed by UV spectrophotometric measurements. For the Zn2+–gsh system, a more complex speciation model was obtained with the formation of ZnL, ZnLH, ZnLH2, ZnL2, ZnL2H, ZnL2H2, ZnLOH and ZnL2OH species. From the dependence of formation constants on temperature, rough ΔH values were evaluated: the main contribution to the complexation free energy is entropic in nature, with small enthalpic values. Moreover, from the dependence on ionic strength, formation constants extrapolated at I = 0 mol L−1 were obtained. The sequestering ability of the ligands towards Pb2+ and Zn2+ was evaluated by determining the pL0.5, i.e. the −log of the concentration of the ligand able to complex half of the metal ion fraction. All these ligands show good sequestering ability. For Pb2+–cys, –psh and –gsh systems, pL0.5 reaches the value of 8.2, 9.0 and 5.9, respectively, at pH = 7, I = 0.1 mol L−1 and t = 25 °C. Under the same experimental conditions, the sequestering ability of gsh towards Zn2+ is lower, with pL0.5 = 4.1.

Anti-apoptotic Bcl-2 enhancing requires FGF-2/FGF receptor 1 binding in mouse osteoblasts.

In this study, we investigated the role of prostaglandin F2α (PGF2α) in mouse osteoblast survival and the function of fibroblast growth factor 2 (FGF‐2) and fibroblast growth factor receptor 1 (FGFR1) in this process. In particular, for the first time, we demonstrated that PGF2α increased osteoblast survival in a dose‐dependent manner and we showed that the effect is correlated with an increase in Bcl‐2/Bax ratio. Furthermore, we demonstrated that PGF2α caused a decrement of the active caspases 9 and 3. By blocking FGF‐2 with the specific neutralizing antibody and by depletion of FGFR1 gene with a specific siRNA, we showed that FGFR1 and FGF‐2 are critical for the increment of Bcl‐2/Bax ratio and the decrement of the active caspases 9 and 3, induced by PGF2α. Moreover, transmission electron microscopy studies showed that PGF2α increased binding of FGF‐2 and FGFR1 and co‐localization of reactive sites at plasma membrane level. In conclusion, we report a novel mechanism in which PGF2α induces FGF‐2 binding to its specific cell surface receptor 1 leading to a cascade pathway that culminates with increased mouse osteoblast survival. J. Cell. Physiol. 214:145–152, 2008.

Thermal analysis and health safety

Hardwood dust is a human carcinogen; upon inhalation, it can cause sinonasal adenocarcinoma. Softwood, on the other hand, is only suspected of carcinogenic properties. However, the toxicology-based recommended exposure limits for hardwood and softwood dust in working environments have been derived identically. While it is very simple to distinguish the wood by morphological evaluations, the wood dust produced in working activities does not allow differentiation. Thermal analysis, especially thermogravimetry, was applied to evaluate the different characteristic thermal profile of standard hardwood and softwood dusts. The different TG and DTG traces allow to propose thermogravimetry as a new tool to distinguish and quantify the different dust origin.