In vitro expansion of tissue cells by conditional proliferation.

Cell therapies rely on the implantation of well-characterized functional cells with defined properties. Often, the cells of interest do not proliferate in vitro and thus cannot be expanded to the amount needed for characterization, purification, manipulation, or cloning. Here, we describe a method that allows the reversible expansion of cells by the introduction of a proliferator gene controlled by a regulatable expression module.

Soluble VEGF receptors.

The three human VEGF receptors 1-3 mediate biological signals important for new blood vessel formation and lymphangiogenesis. Soluble VEGF receptors contain all the information necessary for high affinity ligand binding and have been used as experimental tools and regulators in several angiogenic in vitro and in vivo models. Recombinant receptor molecules can be used for specific inhibition of VEGF mediated signal transduction and for blocking tumor angiogenesis by limiting the amount of VEGF secreted from tumor cells or stroma cells.

Renaturation and purification of bone morphogenetic protein-2 produced as inclusion bodies in high-cell-density cultures of recombinant Escherichia coli.

Eschericha coli was genetically engineered to produce recombinant human bone morphogenetic protein-2 (rhBMP-2) in a non-active aggregated form using a temperature-inducible expression system. High concentrations of both biomass (75 g cell dry weight per liter of culture broth) and inactive rhBMP-2 (8.6 gl(-1)) were obtained by applying a high-cell-density cultivation procedure.

The microbial diversity in picoplankton enrichment cultures: a molecular screening of marine isolates.

Picoplankton bacteria from a North Sea water sample were cultured under a variety of different conditions (nutrients, temperature, light, agitation, adhesion). Fluorescent in situ hybridization (FISH) analysis of the enrichments showed complex communities which were dominated by gamma-Proteobacteria or beta-Proteobacteria, followed by alpha-Proteobacteria and bacteria from the Cytophaga/Flavobacterium/Bacteroides (CFB) cluster. Among 410 isolates, a high degree of diversity was found, both with respect to colony color and morphology and with respect to genetic diversity.

Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant Pseudomonas putida strain.

A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.

Expression and localization of placenta growth factor and PlGF receptors in human meningiomas.

It has previously been suggested that in human brain tumours, endothelial cell proliferation during angiogenesis is regulated by a paracrine mechanism involving vascular endothelial growth factor (VEGF) and its receptors (VEGF receptor 1 and VEGF receptor 2). The mechanism of growth factor up-regulation is based on hypoxic activation of mRNA expression and mRNA stabilization and genetic events, leading to an increase of growth factor gene expression. The role of the other newly discovered VEGF family members with a high specificity for endothelial cells in the pathogenesis of glial neoplasms is unknown.

Detection and quantification of complexed and free soluble human vascular endothelial growth factor receptor-1 (sVEGFR-1) by ELISA.

Vascular endothelial growth factor (VEGF) is an important factor for endothelial cell proliferation and a key regulator of blood vessel development in embryos and angiogenesis in adult tissues. Its biological activity is mediated by two receptor tyrosine kinases, VEGFR-1 (Flt-1) and VEGFR-2 (KDR). In contrast to VEGFR-2, a naturally occurring soluble form of the VEGFR-1 (sVEGFR-1) is produced by endothelial cells by differential splicing of the flt-1 gene, and it is a secreted gene product.

Efficacy in aquatic microcosms of a genetically engineered pseudomonad applicable for bioremediation.

A genetically engineered microorganism (GEM), Pseudomonas sp. B13 FRI (pFRC20P) (abbreviated FR120), has previously been engineered to simultaneously mineralize mixtures of methylated and chlorinated benzoic acids and phenols through a modified ortho cleavage pathway. In this study, its performance was investigated both in different types of aquatic microcosms and in pure culture to determine (1) if under simulated in situ conditions the genetically engineered pathway effectively removes mixtures of model pollutants simultaneously, quickly, and completely; (2) where the optimum pollutant concentration range for this activity lies; and (3) how physical, chemical, and biological factors in the microcosms influence degradation rates.

Pseudomonas putida Strains Which Constitutively Overexpress Mercury Resistance for Biodetoxification of Organomercurial Pollutants.

Improved biocatalysts for mercury (Hg) remediation were generated by random mutagenesis of Pseudomonas putida with a minitransposon containing merTPAB, the structural genes specifying organomercury resistance. Subsequent selection for derivatives exhibiting elevated resistance levels to phenylmercury allowed the isolation of strains that constitutively express merTPAB at high levels, conferring the ability to cleave Hg from an organic moiety and reduce the freed Hg(II) to the less toxic elemental form, Hg, at greater rates. Constitutive overexpression of merTPAB had no apparent effect on culture growth rates, even when Hg(II) was initially present at otherwise toxic concentrations.

Bacterial infection of wounds: fibronectin-mediated adherence group A and C streptococci to fibrin thrombi in vitro.

Adherence of group A, B, and C streptococci to fibrin thrombi was studied by using a novel fluorochrome microassay carried out in microdilution plates in which fibrin thrombi had been prepared by clotting citrated human, cattle, or horse plasma. Substantial adherence was observed with various strains of group A and C streptococci, whereas little was observed with group B streptococci. Adherence of all group A and C streptococcal strains decreased by up to 40% when fibronectin was depleted from the plasmas used for preparing fibrin thrombi, and fibronectin repletion increased adherence of streptococci in a dose-dependent manner.