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Many industrial problems that arise during petroleum processing are related to the high concentration of asphaltenes. A good knowledge of the chemical composition of these macromolecules and a detailed understanding of the evolution of the colloïdal structures present in oil and its derivatives can play a decisive role in improving processing facilities. Asphaltenes are defined by their insolubility in n-heptane. Soluble molecules are called maltenes which can be fractionated by liquid chromatography in so-called resins, aromatic and saturated fractions. The major part of the research carried out on these complex molecules concerned the chemical composition determination from powerful techniques measurements as for instance IR or NMR methods. Nevertheless, very little information on the colloïdal structure of asphaltenes or resins in pure solvent or in real systems is accessible.The molecular weight determination was the first objective; several techniques, as vapour pressure osmometry (VPO), were used. The main conclusion of these determinations was the huge variation of the molecular weight measured by different methods. We used X-ray and neutron small angle scattering techniques in order to deduce the size polydispersity and the weight average molecular weight. Different systems as (i) asphaltenes or resins in solution with different solvents, or (ii) asphaltene and resin mixtures in suspension with good or bad solvents were investigated as a function of temperature increase. We have exhibited that the aggregation number, i.e. the number of smaller entities , can strongly vary with solvent composition and temperature. Resins appear as very good solvent for asphaltene molecules. Scattering measurements often exhibit strong scattered intensity at small scattering vector, showing the presence in the suspension of large heterogeneities in diluted solutions of asphaltenes and resins. We can suggest that these heterogeneities are due to concentration fluctuations. It exists in the diluted suspension regions more or less extended, where the asphaltene concentration is greater than the average asphaltene concentration. Cryo-scanning electron microscopy has confirmed the system inhomogeneity. A two phase system was clearly highlighted. The flocculation process was followed during n-heptane addition by scattering measurements and microscopy observations. Small angle X-ray scattering (SAXS) appears as a powerful tool for non-fractionated systems, as crude oil or other heavy derivatives. Density fluctuations were observed for a vacuum residue. L'industrie pétrolière est souvent confrontée a des problèmes industriels importants liés, entre autre, à la présence d'une forte concentration d'asphaltènes dans les fluides traités. Une meilleure connaissance de la composition de ces molécules et de l'évolution de leur structure colloïdale en solution ou dans leur milieu naturel est d'une grande importance pour mieux comprendre les mécanismes mis en jeu, et ainsi, pouvoir agir et limiter les problèmes rencontrés. Les asphaltènes correspondent à la fraction insoluble dans le n-heptane. Les molécules solubilisées dans l'alcane sont appelées maltènes et peuvent à leur tour être fractionnées par chromatographie en phase liquide; on obtient alors trois nouvelles fractions appelées résines, aromatiques et saturées. La plupart des travaux de recherche réalisés sur ces molécules complexes concernent la détermination de la composition chimique obtenue à l'aide de diverses techniques d'analyse telles la spectroscopie infrarouge et la résonance magnétique nucléaire. En revanche, peu d'informations sur la macrostructure colloïdale des asphaltènes sont disponibles dans la littérature. La détermination de la masse moléculaire a été le premier objectif : plusieurs méthodes, comme l'osmométrie à tension de vapeur, ont été appliquées. La conclusion principale de ces déterminations est la grande variation de la masse moléculaire mesurée suivant la technique employée. Nous avons fait appel à la diffusion des rayons X et des neutrons aux petits angles afin de mesurer la polydispersité en taille et la masse moléculaire moyenne en poids des macromolécules d'asphaltènes. Nous avons étudié différents systèmes constitués, soit par les asphaltènes ou les résines en solution dans différents solvants, soit par le mélange asphaltènes et résines en solution dans de plus ou moins bons solvants. Nous avons également suivi l'effet de la température sur ces systèmes. Les résultats obtenus montrent que l'agrégation, en d'autres termes, le nombre d'entités élémentaires formant la molécule, peut fortement varier en fonction de la nature du solvant et de la température. Les résines apparaissent comme un très bon solvant des asphaltènes. Les mesures de diffusion montrent une forte intensité diffusée à petites valeurs du vecteur de diffusion; elle traduit la présence dans le milieu d'hétérogénéités de taille assez étendue probablement dues à des fluctuations de la concentration en asphaltènes. Ainsi, il existe dans la suspension des régions plus ou moins étendues où la concentration en asphaltènes est supérieure à la concentration moyenne. La microscopie en mode cryogénique a permis de confirmer l'inhomogénéité du système. Un milieu composé de deux phases a clairement été visualisé. La diffusion des rayons X aux petits angles s'avère être une technique importante pour étudier les milieux non fractionnés, comme les bruts ou les résidus de distillation, pour lesquels aucune séparation au n-heptane n'a été réalisée. Nous avons pu mettre en évidence, pour ces systèmes, l'existence de fluctuations de densité à grande échelle.

Afin d'élaborer un modèle thermodynamique capable de décrire la floculation des asphaltènes en s'appuyant au maximum sur la réalité physicochimique, nous nous sommes efforc In order to develop a thermodynamic model able to describe the flocculation of asphaltenes according to their physicochemical properties, we have tried to give a better definition of the asphaltenes chemical structure and to show its influence on the mechanism of aggregation in solution. This work consisted in :- putting in evidence the physical and chemical polydispersity of asphaltenes;- studying simultaneously the nature and the localization of the chemical functions in the asphaltene oligomers (elemental analysis, analysis of the pyrolysed products, etc.) and their capacity to aggregate in solution (X-ray diffusion) to better understand the aggregation mechanims and to identify the functions responsible of this aggregation;- establishing a relation between the proportion of these functions and the size of the aggregates in order to take it in account in the thermodynamic model.The fractionation of a sample of asphaltenes with increasing quantities of n-heptane has allowed to separate different classes of aggregates. For each added quantity of n-heptane, the sample of asphaltenes has been separated in an insoluble fraction and a soluble one. The insoluble fraction contains the aggregates which firstly floculate. The elemental composition of each fraction has been determined by elemetal analysis. The pyrolysis in an open medium has allowed to break the aggregates in elementary patterns, the nature of the different patterns has been determined by liquid and gazeous chromatography. The size of the aggregates has been observed by X-ray diffusion.The results of this chemical characterization have shown that the initial sample of asphaltenes is formed by a group of oligomers having different elemental compositions and different chemical structures. The aggregates which firstly floculate, are the more aromatic and the richer in heteroatoms.The analysis of X-ray diffusion has underlined at once the physical polydispersity of the asphaltenes sample. It has shown that the aggregates which firstly floculate are the biggest in size.From this experimental set of data, it seems possible to describe the asphaltenes physical distribution in solution with a Flory's aggregation equilibrium for which the constant would be characteristic of their chemical structure.

The use of biological agents combined with methotrexate ( MTX) in rheumatoid arthritis ( RA) patients has strongly improved disease outcome. In this study, the effects of abatacept on the size and function of circulating B and T cells in RA patients not responding to anti-tumour necrosis factor ( TNF)-α have been analysed, with the aim of identifying immunological parameters helpful to choosing suitable tailored therapies. We analysed the frequency of peripheral B and T cell subsets, B cell function and T regulatory cell ( Treg) inhibitory function in 20 moderate/severe RA patients, according to the European League Against Rheumatism ( EULAR)/ American College of Rheumatology ( ACR) criteria, primary non-responders to one TNF-α blocking agent, who received abatacept + MTX. Patients were studied before and 6 months after therapy. We found that abatacept therapy significantly reduced disease activity score on 44 joints (DAS)/erythrocyte sedimentation rate ( ESR) values without causing severe side effects. The size of the circulating B and T cell compartments in RA patients was not significantly different from healthy donors, but B cell proliferation and plasma cell differentiation was impaired before therapy and restored by abatacept. While Treg cell frequency was normal, its inhibitory function was absent before therapy and was partially recovered 6 months after abatacept. B and Treg cell function is impaired in RA patients not responding to the first anti- TNF-α agent. Abatacept therapy was able to rescue immune function and led to an effective and safe clinical outcome, suggesting that RA patients, in whom anti- TNF-α failed, are immunologically prone to benefit from an agent targeting a different pathway. [ABSTRACT FROM AUTHOR]

X-linked inhibitor of apoptosis protein (XIAP) is a member of the inhibitor of apoptosis proteins family that selectively binds and inhibits caspase-3, -7 and -9. As such, XIAP is an extremely potent suppressor of apoptosis and an attractive target for cancer treatment. Che-1 is an antiapoptotic agent involved in the control of gene transcription and cell proliferation. Recently, we showed that the checkpoint kinases ATM/ATR and checkpoint kinase 2 physically and functionally interact with Che-1 and promote its phosphorylation and accumulation in response to DNA damage. These Che-1 modifications induce transcription of p53, and Che-1 depletion strongly sensitizes tumor cells to anticancer drugs. Here we show that Che-1 activates XIAP expression in response to DNA damage. This effect is mediated by Che-1 phosphorylation and requires NF-κB. Notably, we found that XIAP expression is necessary for antiapoptotic activity of Che-1 and that in vivo downregulation of Che-1 by small interference RNA strongly enhanced the cytotoxicity of anticancer drugs.Cell Death and Differentiation (2008) 15, 515–520; doi:10.1038/sj.cdd.4402284; published online 30 November 2007 [ABSTRACT FROM AUTHOR]

One of the main problems in the study or industrial application of transesterification processes for vegetable oils is how to measure the methyl ester content. In this work, a quick analytical method was developed for assessing the methyl ester content of purified 'fuel grade' transesterification products by applying a simple correlation with viscosity. The correlation was tested on a wide range of samples with various methyl ester contents; the results were in agreement with the values measured by gas-chromatographic analysis. In a defined range of weight fractions the correlation allows for the determination of the methyl ester content of purified transesterification products by a single viscosity measurement. This method is especially suitable for process control purposes as it determines the methyl ester content quickly and simply. [ABSTRACT FROM AUTHOR]

Abstract Background Nucleic acids designed to modulate the expression of target proteins remain a promising therapeutic strategy in several diseases, including cancer. However, clinical success is limited by the lack of efficient intracellular delivery. In this study we evaluated whether electroporation could increase the delivery of antisense oligodeoxynucleotides against bcl-2 (G3139) as well as the efficacy of combination chemotherapy in human melanoma xenografts. Methods Melanoma-bearing nude mice were treated i.v. with G3139 and/or cisplatin (DDP) followed by the application of trains of electric pulses to tumors. Western blot, immunohistochemistry and real-time PCR were performed to analyze protein and mRNA expression. The effect of electroporation on muscles was determined by histology, while tumor apoptosis and the proliferation index were analyzed by immunohistochemistry. Antisense oligodeoxynucleotides tumor accumulation was measured by FACS and confocal microscopy. Results The G3139/Electroporation combined therapy produced a significant inhibition of tumor growth (TWI, more than 50%) accompanied by a marked tumor re-growth delay (TRD, about 20 days). The efficacy of this treatment was due to the higher G3139 uptake in tumor cells which led to a marked down-regulation of bcl-2 protein expression. Moreover, the G3139/EP combination treatment resulted in an enhanced apoptotic index and a decreased proliferation rate of tumors. Finally, an increased tumor response was observed after treatment with the triple combination G3139/DDP/EP, showing a TWI of about 75% and TRD of 30 days. Conclusions These results demonstrate that electroporation is an effective strategy to improve the delivery of antisense oligodeoxynucleotides within tumor cells in vivo and it may be instrumental in optimizing the response of melanoma to chemotherapy. The high response rate observed in this study suggest to apply this strategy for the treatment of melanoma patients.

Abstract Background Cathepsins represent a group of proteases involved in determining the metastatic potential of cancer cells. Among these are cysteinyl- (e.g. cathepsin B and cathepsin L) and aspartyl-proteases (e.g. cathepsin D), normally present inside the lysosomes as inactive proenzymes. Once released in the extracellular space, cathepsins contribute to metastatic potential by facilitating cell migration and invasiveness. Results In the present work we first evaluated, by in vitro procedures, the role of cathepsins B, L and D, in the remodeling, spreading and invasiveness of eight different cell lines: four primary and four metastatic melanoma cell lines. Among these, we considered two cell lines derived from a primary cutaneous melanoma and from a supraclavicular lymph node metastasis of the same patient. To this purpose, the effects of specific chemical inhibitors of these proteases, i.e. CA-074 and CA-074Me for cathepsin B, Cathepsin inhibitor II for cathepsin L, and Pepstatin A for cathepsin D, were evaluated. In addition, we also analyzed the effects of the biological inhibitors of these cathepsins, i.e. specific antibodies, on cell invasiveness. We found that i) cathepsin B, but not cathepsins L and D, was highly expressed at the surface of metastatic but not of primary melanoma cell lines and that ii) CA-074, or specific antibodies to cathepsin B, hindered metastatic cell spreading and dissemination, whereas neither chemical nor biological inhibitors of cathepsins D and L had significant effects. Accordingly, in vivo studies, i.e. in murine xenografts, demonstrated that CA-074 significantly reduced human melanoma growth and the number of artificial lung metastases. Conclusions These results suggest a reappraisal of the use of cathepsin B inhibitors (either chemical or biological) as innovative strategy in the management of metastatic melanoma disease.

Abstract Background Nitric oxide-releasing nonsteroidal antiinflammatory drugs (NO-NSAIDs) are reported to be safer than NSAIDs because of their lower gastric toxicity. We compared the effect of a novel NO-releasing derivate, NCX 4040, with that of aspirin and its denitrated analog, NCX 4042, in in vitro and in vivo human colon cancer models and investigated the mechanisms of action underlying its antitumor activity. Methods In vitro cytotoxicity was evaluated on a panel of colon cancer lines (LoVo, LoVo Dx, WiDr and LRWZ) by sulforhodamine B assay. Cell cycle perturbations and apoptosis were evaluated by flow cytometry. Protein expression was detected by Western blot. In the in vivo experiments, tumor-bearing mice were treated with NCX 4040, five times a week, for six consecutive weeks. Results In the in vitro studies, aspirin and NCX 4042 did not induce an effect on any of the cell lines, whereas NCX 4040 produced a marked cytostatic dose-related effect, indicating a pivotal role of the -NO2 group. Furthermore, in LoVo and LRWZ cell lines, we observed caspase-9 and -3-mediated apoptosis, whereas no apoptotic effect was observed after drug exposure in WiDr or LoVo Dx cell lines. In in vivo studies, both NCX 4040 and its parental compound were administered per os. NCX 4040 induced a 40% reduction in tumor weight. Conversely, aspirin did not influence tumor growth at all. Conclusions NCX 4040, but not its parental compound, aspirin, showed an in vitro and in vivo antiproliferative activity, indicating its potential usefulness to treat colon cancer.