Human lung cell growth is not stimulated by lead ions after lead chromate-induced genotoxicity

Chromate compounds are known human lung carcinogens. Water solubility is an important factor in the carcinogenicity of these compounds with the most potent carcinogenic compounds being water-insoluble or ‘particulate’. Previously we have shown that particulate chromates dissolve extracellularly releasing chromium (Cr) and lead (Pb) ions and only the Cr ions induce genotoxicity. Pb ions have been considered to have epigenetic effects and it is thought that these may enhance the carcinogenic activity of lead chromate, perhaps by stimulating Cr-damaged cells to divide. However, this possibility has not been directly tested. Accordingly, we investigated the ability of Pb ions to stimulate human lung cells and possibly force lead chromate-damaged cells to grow. We found that at concentrations of lead chromate that induced damage, human lung cells exhibited cell cycle arrest and growth inhibition that were very similar to those observed for sodium chromate. Moreover, we found that soluble Pb ions were not growth stimulatory to human lung cells and in fact induced progressive mitotic arrest. These data indicate that lead chromate-generated Cr ions cause growth inhibition and cell cycle arrest and that Pb does not induce epigenetic effects that stimulate chromate-damaged cells to grow.     

Generation and characterization of two transgenic mouse lines expressing human ApoE2 in neurons and glial cells

Apolipoprotein E (apoE) isoforms are key determinants of susceptibility to late-onset Alzheimer's disease (AD). The epsilon 4 and epsilon 2 alleles have been associated with increased and decreased risk for AD, respectively. We have generated and characterized transgenic mice in which the human apoE2 gene is expressed under the control of the platelet-derived growth factor B-chain (PDGF-B) promoter, or the transferrin (TF) promoter. S1 nuclease analysis and immunoblotting showed that the PDGF-B apoE2 mice express apoE2 exclusively in the brain whereas the TF apoE2 mice express apoE2 in the liver and in the brain. In the TF apoE2 mouse line, apoE2 is also detected in the plasma. The PDGF-B apoE2 and the TF apoE2 transgenic mice were bred back to apoE(-)(/)(-) background. Immunohistochemical analysis showed that the PDGF apoE2 x apoE(-)(/)(-) and the TF apoE2 x apoE(-)(/)(-) mice express human apoE2 within the neocortex in hippocampal neurons and glial cells, respectively. ApoE(-)(/)(-) mice have been shown to develop age-dependent loss of synaptophysin. Immunoblotting of mouse brain extracts and immunohistochemical analysis of brain sections showed that apoE expression in both apoE2 x apoE(-)(/)(-) transgenic lines was associated with significant recovery of brain synaptophysin levels as compared to the levels of apoE(-)(/)(-) littermates of the same age. These apoE2-expressing mice, when bred back on amyloid precursor protein (APP) transgenic mice or other mouse lines featuring alterations in lipoprotein metabolism, may provide new mouse models for elucidating the role of apoE2 in lipid homeostasis in the brain and in the pathogenesis of AD.     

Fortification of a protein-free cell culture medium with plant peptones improves cultivation and productivity of an interferon-γ-producing CHO cell line

A strong tendency is currently emerging to remove not only serum but also any product of animal origin from animal cell culture media during production of recombinant proteins. This should facilitate downstream processing and improve biosafety. One way consists in the fortification of protein-free nutritive media with plant protein hydrolysates. To investigate the effects of plant peptones on mammalian cell cultivation and productivity, CHO 320 cells, a clone of CHO K1 cells genetically modified to secrete human interferon-gamma (IFN-gamma), were first adapted to cultivation in suspension in a protein-free medium. Both cell growth and IFN-gamma secretion were found to be equivalent to those reached in serum-containing medium. Eight plant peptones, selected on the basis of their content in free amino acids and oligopeptides, as well as molecular weight distribution of oligopeptides, were tested for their ability to improve culture parameters. These were improved in the presence of three peptones, all having an important fraction of oligopeptides ranging from 1 to 10 kDa and a small proportion of peptides higher than 10 kDa. These peptones do not seem to add significantly to the nutritive potential to basal protein-free nutritive medium. Nevertheless, supplementation of an oligopeptide-enriched wheat peptone improved cell growth by up to 30% and IFN-gamma production by up to 60% in shake-flask experiments. These results suggest that the use of plant peptones with potential growth factor-like or antiapoptotic bioactivities could improve mammalian cell cultivation in protein-free media while increasing the product biosafety.     

Contribution of the hormone-response elements of the proximal ApoA-I promoter, ApoCIII enhancer, and C/EBP binding site of the proximal ApoA-I promoter to the hepatic and intestinal expression of the ApoA-I and ApoCIII genes in transgenic mice

We have generated and studied the pattern of expression of transgenic mouse lines carrying the human apoA-I and apoCIII gene cluster mutated at different sites. In two lines, we have either mutated the hormone-response element (HRE) of element G of the apoCIII enhancer or the C/EBP binding site of the proximal apoA-I promoter. In a third line, we have mutated the two HREs of the apoA-I promoter and the HRE of the apoCIII enhancer. Mutations in the HRE of element G reduced the hepatic and intestinal expressions of the reporter chloramphenicol acetyltransferase (CAT) gene (which substituted the apoCIII gene) to 4 and 13% of the wild-type (WT) control, whereas the hepatic and intestinal expressions of the apoA-I gene were reduced to 92 and 25% of the WT control, respectively. A mutation in the C/EBP site increased the hepatic and intestinal expressions of the apoA-I gene approximately 1.25- and 1.6-fold, respectively, and did not affect the expression of the CAT gene. The mutation in the three HNF-4 binding sites of the apoA-I promoter/apoCIII enhancer nearly abolished the expression of apoA-I and the reporter CAT gene in all tissues. These findings establish the importance of the HREs for the hepatic and intestinal expressions of the apoA-I and apoCIII genes and suggest that C/EBP does not play a central role in the expression of the apoA-I gene.     

Rupture of totally implantable central venous access devices (Intraports) in patients with cancer: report of four cases

Background  

Totally implantable central venous access devices (intraports) are commonly used in cancer patients to administer chemotherapy or parenteral nutrition. Rupture of intraport is a rare complication.     

Sonoporation: Mechanistic insights and ongoing challenges for gene transfer

Microbubbles first developed as ultrasound contrast agents have been used to assist ultrasound for cellular drug and gene delivery. Their oscillation behavior during ultrasound exposure leads to transient membrane permeability of surrounding cells, facilitating targeted local delivery. The increased cell uptake of extracellular compounds by ultrasound in the presence of microbubbles is attributed to a phenomenon called sonoporation. In this review, we summarize current state of the art concerning microbubble–cell interactions and cellular effects leading to sonoporation and its application for gene delivery. Optimization of sonoporation protocol and composition of microbubbles for gene delivery are discussed.     

Carbon Source-Induced Modifications in the Mycolic Acid Content and Cell Wall Permeability of Rhodococcus erythropolis E1

The influence of the carbon source on cell wall properties was analyzed in an efficient alkane-degrading strain of Rhodococcus erythropolis (strain E1), with particular focus on the mycolic acid content. A clear correlation was observed between the carbon source and the mycolic acid profiles as estimated by high-performance liquid chromatography and mass spectrometry. Two types of mycolic acid patterns were observed after growth either on saturated linear alkanes or on short-chain alkanoates. One type of pattern was characterized by the lack of odd-numbered carbon chains and resulted from growth on linear alkanes with even numbers of carbon atoms. The second type of pattern was characterized by mycolic acids with both even- and odd-numbered carbon chains and resulted from growth on compounds with odd-numbered carbon chains, on branched alkanes, or on mixtures of different compounds. Cellular short-chain fatty acids were twice as abundant during growth on a branched alkane (pristane) as during growth on acetate, while equal amounts of mycolic acids were found under both conditions. More hydrocarbon-like compounds and less polysaccharide were exposed at the cell wall surface during growth on alkanes. Whatever the substrate, the cells had the same affinity for aqueous-nonaqueous solvent interfaces. By contrast, bacteria displayed completely opposite susceptibilities to hydrophilic and hydrophobic antibiotics and were found to be strongly stained by hydrophobic dyes after growth on pristane but not after growth on acetate. Taken together, these data show that the cell wall composition of R. erythropolis E1 is influenced by the nutritional regimen and that the most marked effect is a radical change in cell wall permeability.