The proposed method and analysis of luminance contrast values will help revisit the viability of the existing lighting guidelines and develop perceptual lighting metrics that take into account the lighting-related needs and preferences of senior populations.
A sample is considered photo-cytotoxic if it causes the cell culture to be < 50% viable when exposed to light and if the % cell viability of the culture with the sample in the dark is more than double the % cell viability in the presence of light [5 8].
In a statement Tuesday, the company stressed that the move was not a recall, but was based on the products' commercial viability "in light of changing market dynamics, and is not related to safety or efficacy".
"For the past several months, teams from both companies have been studying the viability of the projects in light of significant changes in business conditions since the projects were announced in January and April of 2008," Chrysler and Nissan said in a joint statement.
Figure 33a shows the viability of HeLa cells after light irradiation by 662-nm laser at a power density of 0.2 W/cm2 for 5 min and Fig. 33b shows the changes of Ce6 fluorescence intensity in cells as a function of incubation time.
With the separate use of riboflavin or UVA-light illumination, viability of KC keratocytes did not change significantly compared to controls (P > 0.34).
Preliminary experiments showed that both cell lines maintained >90% viability, based on flow cytometric assessment of light scatter and propidium iodide exclusion, following exposure to up to 60 μ M gemcitabine for up to 48 h.
Cercariae were collected by exposing infected snails to light and the number and viability of cercariae were determined under a light microscope before challenge.
The HA treatment groups in the presence of light showed greater reduced viability count compared to darkness exposure groups.
