CCN2/CTGF silencing blocks cell aggregation in embryonal carcinoma P19 cell

Connective tissue growth factor (CCN2/CTGF) is a matricellular-secreted protein involved in extracellular matrix remodeling. The P19 cell line is an embryonic carcinoma line widely used as a cellular model for differentiation and migration studies. In the present study, we employed an exogenous source of CCN2 and small interference RNA to address the role of CCN2 in the P19 cell aggregation phenomenon. Our data showed that increasing CCN2 protein concentrations from 0.1 to 20 nM decreased the number of cell clusters and dramatically increased cluster size without changing proliferation or cell survival, suggesting that CCN2 induced aggregation. In addition, CCN2 specific silencing inhibited typical P19 cell aggregation, which could be partially rescued by 20 nM CCN2. The present study demonstrates that CCN2 is a key molecule for cell aggregation of embryonic P19 cells.

CCN2/CTGF silencing blocks cell aggregation in embryonal carcinoma P19 cell.

Connective tissue growth factor (CCN2/CTGF) is a matricellular-secreted protein involved in extracellular matrix remodeling. The P19 cell line is an embryonic carcinoma line widely used as a cellular model for differentiation and migration studies. In the present study, we employed an exogenous source of CCN2 and small interference RNA to address the role of CCN2 in the P19 cell aggregation phenomenon. Our data showed that increasing CCN2 protein concentrations from 0.1 to 20 nM decreased the number of cell clusters and dramatically increased cluster size without changing proliferation or cell survival, suggesting that CCN2 induced aggregation. In addition, CCN2 specific silencing inhibited typical P19 cell aggregation, which could be partially rescued by 20 nM CCN2. The present study demonstrates that CCN2 is a key molecule for cell aggregation of embryonic P19 cells.

Isolation of Legionella species/serogroups from water cooling systems compared with potable water systems in Spanish healthcare facilities.

Surveillance of Legionella spp. in hospital water systems was performed in forty-four inpatient healthcare facilities in Spain during 2005-2006. A total of 2,341 samples were collected: 470 from cooling systems (cooling towers) and 1,871 from potable water systems. The latter included 211 from cold-water tanks and 260 from hot-water tanks, totalling 471 from central water reservoirs 136 from showers, 1,172 from unfiltered taps and 92 from filtered taps, totalling 1,400 from peripheral points. Temperature, chlorine levels and the presence of Legionella spp. were determined. In all, 373 (15.9%) samples yielded Legionella spp. Significantly higher isolation rates were obtained from cooling towers (23.8%) versus cold- and hot-water tanks (approximately 4.7%), due to the significantly higher number of samples positive for serogroup 1 (19.4 vs 0.9-3.5%). In potable water systems, no differences were found between central water tanks and showers, but significant differences in isolation rates between central water tanks and unfiltered taps were observed (4.7 vs 19.6%) due to differences in non-serogroup 1 L. pneumophila. Filters significantly decreased isolation rates of these serotypes (11 vs 0%). Some seasonal differences were noted, with higher isolation rates in summer for legionella serogroup 1 in cooling systems and for L. pneumophila serogroups 2-14 in potable water systems. In regression models, higher temperatures were associated with colonisation in cooling systems, while lower chlorine levels were associated with colonisation in potable water systems.

Candida albicans exocellular antigens released into a synthetic culture medium: characterization and serological response in rabbits.

Different exocellular extracts were isolated by concentrating the supernatants of yeast- and mycelial-phase Candida albicans cultures incubated in a synthetic medium. The only difference between the extracts obtained from the two phases was the presence in those obtained from mycelial cultures of a polysaccharide-rich, high-molecular-mass component, migrating in SDS-polyacrylamide gels at a position that would correspond to proteins with molecular masses of 245-265 kDa. The electrophoretic band patterns obtained before and after concanavalin A-Sepharose 4B affinity column treatments confirmed that the 245-265 kDa band was the only one of mannoprotein nature. The extract obtained from 24 h mycelial-phase culture (EA) was selected as the exocellular antigen for this work. The dry weight of EA obtained from 1 litre of culture medium was 30 mg; it contained 53% carbohydrate (18.3% glucose and 21.7% mannose measured by gas-liquid chromatography) and 10% protein. Rabbit antisera against EA were absorbed with yeast-phase organisms and used to stain Western blots of gels loaded with EAs. These antisera clearly recognized bands in the 21, 33 and 44 kDa areas. The antiserum obtained was employed to develop a double-antibody enzyme-linked immunosorbent assay for measuring EA concentrations in a culture medium. Most of the EA was released during the exponential phase of growth.

Heavy metals, chlorine and antibiotic resistance in Escherichia coli isolates from ambulatory patients.

The susceptibility of Escherichia coli strains isolated from ambulatory patients to heavy metals, chlorine and antibiotics was evaluated. It seemed that heavy metal resistance was associated with antibiotic resistance. On the other hand, chlorine resistant strains seemed to be more sensitive to antibiotics. Clinical and ecological implications of these results are discussed.

Bleomycin-kanamycin resistance as a marker of the presence of transposon Tn5 in clinical strains of Escherichia coli.

The aminoglycoside modifying enzyme aminoglycoside 3'-phosphotransferase II (APH(3')II) is encoded for on transposon Tn5 by the aphA gene, in the same operon as the ble gene determining bleomycin resistance. To document this linkage 82 kanamycin-resistant Escherichia coli strains of clinical origin were studied; all 18 isolates presenting bleomycin-kanamycin resistance were shown by an enzymatic assay to produce APH(3')II, and the presence of Tn5 was demonstrated by gene hybridization. Similarly, bleomycin-kanamycin resistance was shown to be linked to APH(3')II production in Salmonella spp. The epidemiology of strains with Tn5-encoded APH(3')II may thus be studied, at least in Escherichia coli, by a simple diffusion test using bleomycin and kanamycin discs.

Biochemical and immunochemical study of lysyl oxidase in experimental hepatic fibrosis in the rat.

Lysyl oxidase catalyzes the crosslinking of collagen and elastin. Lysyl oxidase activity was measured and localized in rat liver during the evolution of hepatic fibrosis induced by CCl4. Enzyme activity measured with DL-[6-3H]-lysine-labeled collagen substrates in liver and plasma increased sharply after approximately 3 wk of injection, reached a maximum at 6 wk, and then decreased. The increase in activity correlated histologically with early connective tissue septa formation, and the magnitude of increase was significantly greater than that found for the intracellular collagen biosynthetic enzymes protocollagen prolyl hydroxylase and lysyl hydroxylase. Indirect immunofluorescence studies showed that lysyl oxidase was present in association with collagen in the extracellular space. However, it was not possible to correlate the distribution pattern with a particular liver cell type. These observations suggest that serial measurements of lysyl oxidase activity in liver or plasma may be useful for correlating changes in connective tissue formation with histologic connective tissue deposition.