Das Atomgewicht des Urans und des Bleis

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Rheological and biological properties of a hydrogel support for cells intended for intervertebral disc repair

<p>Abstract</p> <p>Background</p> <p>Cell-based approaches towards restoration of prolapsed or degenerated intervertebral discs are hampered by a lack of measures for safe administration and placement of cell suspensions within a treated disc. In order to overcome these risks, a serum albumin-based hydrogel has been developed that polymerizes after injection and anchors the administered cell suspension within the tissue.</p> <p>Methods</p> <p>A hydrogel composed of chemically activated albumin crosslinked by polyethylene glycol spacers was produced. The visco-elastic gel properties were determined by rheological measurement. Human intervertebral disc cells were cultured <it>in vitro </it>and <it>in vivo </it>in the hydrogel and their phenotype was tested by reverse-transcriptase polymerase chain reaction. Matrix production and deposition was monitored by immuno-histology and by biochemical analysis of collagen and glycosaminoglycan deposition. Species specific <it>in situ </it>hybridization was performed to discriminate between cells of human and murine origin in xenotransplants.</p> <p>Results</p> <p>The reproducibility of the gel formation process could be demonstrated. The visco-elastic properties were not influenced by storage of gel components. <it>In vitro </it>and <it>in vivo </it>(subcutaneous implants in mice) evidence is presented for cellular differentiation and matrix deposition within the hydrogel for human intervertebral disc cells even for donor cells that have been expanded in primary monolayer culture, stored in liquid nitrogen and re-activated in secondary monolayer culture. Upon injection into the animals, gels formed spheres that lasted for the duration of the experiments (14 days). The expression of cartilage- and disc-specific mRNAs was maintained in hydrogels <it>in vitro </it>and <it>in vivo</it>, demonstrating the maintenance of a stable specific cellular phenotype, compared to monolayer cells. Significantly higher levels of hyaluronan synthase isozymes-2 and -3 mRNA suggest cell functionalities towards those needed for the support of the regeneration of the intervertebral disc. Moreover, mouse implanted hydrogels accumulated 5 times more glycosaminoglycans and 50 times more collagen than the <it>in vitro </it>cultured gels, the latter instead releasing equivalent quantities of glycosaminoglycans and collagen into the culture medium. Matrix deposition could be specified by immunohistology for collagen types I and II, and aggrecan and was found only in areas where predominantly cells of human origin were detected by species specific <it>in situ </it>hybridization.</p> <p>Conclusions</p> <p>The data demonstrate that the hydrogels form stable implants capable to contain a specifically functional cell population within a physiological environment.</p

Boma Comme Destination Ecotouristique : Atouts, Potentialités et Contraintes

Abstract – This article studied the city of Boma in the “Kongo-central” (Bas-Congo) Province, (DRC), which is considered as favorable city for the ecotourism according to its  the strengths and potentials in tourism. Most unfortunately, the many beautiful sites that exist are abandoned there and sometimes neglected in favor of one or two sights only.Our investigations based on direct observations, review of reports and documents in the Boma City office, Agency of Boma National Tourist Office, and discussion with the representatives of ONT, we obtained some results.I was found the lack of a real policy of adaptation and ecotourism development in the City. The Boma residents as Congoleses had not yet acquired an ecotourism culture. The statistics had shown how many foreigners are so reluctant to consume the tourist product offered by the City. This publication had been focused on the promoting green tourism and the protection of the biodiversity.Keywords: Ecotourism, biodiversity, Boma, green tourism, Kongo-central (Bas-Congo) and DRC. Résume – Cet article étudie la ville de Boma dans la Province du Kongo-central (RDCongo) qui est considérée comme lieu favorable où doit être pratiqué un type particulier du tourisme, au regard des atouts et potentialités qu’elle regorge, il s’agit d’écotourisme. Fort malheureusement, les nombreux et beaux sites naturels qui y existent sont abandonnés et parfois négligés au profit d’un ou deux sites touristiques à peine.En effet, nos investigations basées sur l’observation directe, la revue des rapports et documents de la Mairie de Boma, de l’Agence de l’Office Nationale du Tourisme de Boma, et des travaux de recherche qui ont été réalisés en écotourisme, et l’entretien avec les représentants de l’Agence de l’ONT.Les résultats obtenus montrent que Boma manque d’une politique réelle dans l’adaptation et le développement d’écotourisme. De ce fait, les congolais en général, et les bomatraciens en particulier n’ont pas encore acquis une culture d’écotourisme, et les statistiques montrent combien les étrangers sont un peu trop réticents à consommer le même produit touristique. Cette publication est une vaste sensibilisation à la promotion du tourisme vert et à la protection de notre biodiversité

3-Methyl pyruvate enhances radiosensitivity through increasing mitochondria-derived reactive oxygen species in tumor cell lines

Considerable interest has recently been focused on the special characteristics of cancer metabolism, and several drugs designed to modulate cancer metabolism have been tested as potential anticancer agents. To date, however, very few studies have been conducted to investigate the combined effects of anticancer drugs and radiotherapy. In this study, to evaluate the role of mitochondria-derived reactive oxygen species (ROS) in the radiation-induced cell death of tumor cells, we have examined the effect of 3-methyl pyruvate (MP). MP is a membrane-permeable pyruvate derivative that is capable of activating mitochondrial energy metabolism in human lung carcinoma A549 cells and murine squamous carcinoma SCCVII cells. Pretreatment with MP significantly enhanced radiation-induced cell death in both cell lines, and also led to increases in the mitochondrial membrane potential, intracellular adenosine triphosphate content, and mitochondria-derived ROS production following the exposure of the cells to X-rays. In A549 cells, MP-induced radiosensitization was completely abolished by vitamin C. In contrast, it was partially abolished in SCCVII cells. These results therefore suggest that the treatment of the cells with MP induced radiosensitization via the production of excess mitochondria-derived ROS in tumor cells