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Fig. 5 | Respiratory Research

Fig. 5

From: Propylene glycol, a component of electronic cigarette liquid, damages epithelial cells in human small airways

Fig. 5

PG induces cell apoptosis. SAECs were cultured with 0–4% PG or Gly. Caspase 3/7-positive cells were assessed every 3 h up to 24 h using IncuCyte Zoom. Data were adjusted with cell surface area. A Representative images of SAECs exposure to 4% PG or Gly at 24 h. Green signals indicate caspase 3/7-positive cells. Scale bar = 300 µm. B Effect of PG on caspase 3/7-positive cell count, time-course. C Effect of PG on caspase 3/7-positive cell count at 24 h. Data are expressed as a relative value to control (indicated as a grey bar). D Effect of Gly on caspase 3/7-positive cell count, time-course. E Effect of Gly on caspase 3/7-positive cell count at 24 h. Data are expressed as a relative value to control (indicated as a grey bar). F Effect of PG and Gly on cleaved PARP1 expression at 24 h. Representative western blot images are shown. β-actin was used as a loading control. Band size is indicated on the upper right. Densitometric analysis of cleaved PARP1 expression, normalized to that of β-actin. Data are expressed as a relative value to control (without PG and Gly, indicated as a grey bar). Three batches of SAECs were evaluated on two separate occasions. Values are mean ± SEM. Statistical significance was determined using Two-way ANOVA. PG propylene glycol, Gly glycerol, SAECs small airway epithelial cells, PARP poly (ADP-ribose) polymerase, SEM standard error of the mean

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