Female Sprague-Dawley rats were treated orally with 25mg STE/kg every other day for 90 days.38 In order to obtain information regarding the cytotoxicity of STE, the ultrastructural changes occurring in livers of rats following administration of STE were examined under light and electron microscopy. Groups of rats were killed on days 30, 45, 60, and 90 by decapitation, and livers were fixed for light and electron microscopy.38 Samples of liver from each animal were fixed in paraformaldehyde and glutaraldehyde, pH 7.4, for electron microscopy. A tissue buffer ratio of at least 1:10 was used in all cases. Sections approximately 5^m thick were cut. Samples of livers from each control and experimental animal were fixed in 10% buffered formalin for light microscopy. The samples were dehydrated by standard procedures and embedded in paraffin. Sections approximately 5^m thick were cut, stained with hematoxylin and eosin (H & E), and examined under a light microscope. Electron microscopy revealed that in the perisinusoidal spaces an accumulation of indistinct filamentous material occurred following 60 days of treatment, occupying most of the sinusoids. Moreover, the lipids were in a state of disintegration. Significant increases in 90-kDa protein expression were also observed due to chronic treatment with STE. Western blot analysis using a polyclonal mouse antibody against heat shock/stress protein 90 (HSP90) confirmed that the overexpressed proteins were heat shock/stress proteins (HSPs).38 The HSPs are believed to serve as adaptive or survival functions involving a rapid but transient reprogramming of cellular metabolic activity to protect cells from oxidative damage.39


Both concentration- and time-dependent effects of STE were assessed on cellular viability in a primary culture of human oral keratinocytes (NHOK), derived from oral cavities of normal human subjects, by the Trypan blue exclusion technique.40 The control and STE-treated NHOK cells were trypsinized, centrifuged, and resuspended in culture medium. Each cell suspension (0.10ml) was mixed with 0.1ml Trypan blue solution (0.2% PBS). Live and dead cells were counted using a hemocytometer, and blue-stained cells were counted as nonviable. The percentage viability was calculated based on the percentage of unstained cells. A concentration-dependent effect (0 to 400 ^g/ml) on cell death was observed with treatment of STE, and most cells lost their adhesiveness within 24h when incubated with high concentrations of STE (>250^g/ml). However, 55 to 70% of the cells were still viable.2840

Quit Smoking For Good

Quit Smoking For Good

Quit smoking for good! Stop your bad habits for good, learn to cope with the addiction of cigarettes and how to curb cravings and begin a new life. You will never again have to leave a meeting and find a place outside to smoke, losing valuable time. This is the key to your freedom from addiction, take the first step!

Get My Free Ebook

Post a comment