HeLa cells cell constants

Electrochemical Effect on a HeLa Cell at Constant Potential... 

Fig. 12 Transfection efficiencies for DOTAP/DOPC and MVLBisG2/DOPC complexes in four different cell lines, plotted against the mole fraction of cationic lipid. The data points were obtained at a constant pchg (7 for HeLa cells, 4.5 for all others), corresponding to a constant amount of DNA applied to the cells for each data point in a plot. Remarkably, MVLBisG2 complexes are significantly more transfectant in mouse embryonic fibroblasts, a cell line empirically know to be hard to transfect and of large practical importance as feeder cells for embryonic stem cells. Reprinted with permission from [24]. Copyright 2006 American Chemical Society...

As previously mentioned, degradable microspheres have gained attention as promising delivery vehicles for steroids in postmenopausal therapy. Copolymers of CL and d,l-LA were used to prepare microspheres for prolonged release of progesterone and [5-estradiol. The system offered a constant release for up to 40 days in vitro and 70 days in vivo [226]. Similarly, PCL copolymers have been considered useful for androgen replacement therapy in the treatment of aging men with a testosterone deficiency. Micelles of PCL-block-poly(ethylene oxide) released dihydrotestosterone in a controlled fashion over 30 days. The biocompatibility was confirmed in vitro in a HeLa cell culture [227]. 

Fig. 3A,B. SDS gradient gel electrophoresis and autoradiography of ADP-ribosylated proteins. Permeabilized HeLa cells (5 X 10 ) were incubated for 20 min at 26°C with 0.133 ijM [ P]-NAD, sp.act. 245.8 Ci mmoP, made up to 1 nM or 100 /lAf with non-radioactive NAD. Each assay contained about 5.9 X 10 cpm. Reactions (75 n ) were stopped by adding 75 n of solution containing 2% (w/v) SDS, 50 mM 2-mercaptoethanol, 6 M urea, 10 mM sodium bisulphite, 5 mM 4-aminobenzamidine, 0.5 mM PMSF, 0.15 iig of pepstatin and 0.15 Mg of leupeptin in 100 mM Tris-HCl pH 5.4 and 40% (v/v) glycerol. The mixture was immediately boiled for 4 min. Slab-gel electrophoresis was carried out in a 6-18% linear gradient polyacrylamide gel made in 25 mM sodium phosphate pH 6.8,1% (w/v) SDS and 3 M urea. A 4% stacking gel was used made in 10 mM sodium phosphate pH 6.0. The electrode buffer was 25 mM sodium phosphate pH 6.8, 1% SDS. Gels were subjected to electrophoresis for 6-7 h at a constant current of 40 mA.

Since quantitation of the absolute number of DNA chain breaks is difficult, we chose to express the number of breaks in terms of rad equivalents of DNA breaks [5]. A standard curve was constructed of the first order DNA elution rate through filters under alkaline conditions [5]. Cells were irradiated at doses of 7-rays from 0 to 1000 rad. A plot of the DNA elution rate constant was linear up to 800 rad. Next, the amount of time necessary to repair 400 rad equivalents of DNA damage was determined. The repair rate was linear for about 7. 5 min with completion of repair taking 10 min. We chose a time of 5 min at which time about 50% of the repair of 400 rad was accomplished in cells not exposed to synthetase inhibitors. HeLa cells were irradiated for 400 rad then incubated for 5 min in the presence or absence of synthetase inhibitors to permit DNA repair to be accomplished. Inhibitors utilized were 3-acetamidobenzamide (AAB, = 0.25 ijM), 3-aminobenzamide (AB, = 2.8 [jM), 3-methoxybenzamide (MB, = 0.41 juM), 3-hydroxybenzamide (HB, = 1.05 nM), benzamide (B, = 0.91 iM), and 3-nitrobenzamide (NB, = 1.03 iM) as deter-... 

Fig. 14 SEM image of optical fibre nanoring electrode (a) and cyclic voltammogram for the oxidation of 0.5 M ferrocenemethanol. Simultaneous topographic (c), fluorescence (d) and electrochemical (e) images of a single HeLa cell measured in shear force-regulated constant distance mode. Reproduced from ref. 142 with permission from the American Chemical...

HeLa cells were cultured in a CO2 incubator by controlling the CO2 concentration at 5% at a constant temperature of 35 C. The culture medium was McCOY s 5A mixed with 10% PBS. Cultured HeLa cells were treated with trypsin, washed, and collected by centrifugation. 

Figure 2. Time course of HeLa cell diameter change at a constant potential of -0.6 V vs Ag/AgCl.

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