Effects of allyl methyl trisulfide on glutathione S‐transferase activity and BP‐induced neoplasia in the mouse

Allyl methyl trisulfide (AMT), a constituent of garlic oil, was studied for its effects on glutathione S‐transferase (GST) activity and on benzo[a]pyrene (BP)‐induced neoplasia of the forestomach and lungs of female A/J mice. AMT induced increased GST activity in the forestomach, small bowel mucosa, liver, and lung. The forestomach and small bowel mucosa responded to a single low dose of AMT (3.0 μmol) given by oral intubation, whereas liver and lung were less reactive. A dose schedule of two administrations of 15 μmol AMT given 48 hours apart gave close‐to‐maximum induction in all four tissues and was chosen for investigation of its inhibitory effects. With this dose schedule, AMT produced an inhibition of BP‐induced neoptasia of the forestomach as shown by a greater than 70% reduction in the number of tumors found at the completion of the experiment. Inhibition of pulmonary neoplasia did not occur. AMT is a member of a new class of naturally occurring chemicals that have the capacity to inhibit chemical carcinogenesis.     

Nanoscale mapping of refractive index by using scattering-type scanning near-field optical microscopy

We present a novel method for nanoscale reconstruction of complex refractive index by using scattering-type Scanning Near-field Optical Microscopy (s-SNOM). Our method relies on correlating s-SNOM experimental image data with computational data obtained through simulation of the classical oscillating point-dipole model. This results in assigning a certain dielectric function for every pixel of the s-SNOM images, which further results in nanoscale mapping of the refractive index. This method is employed on human erythrocytes to demonstrate the approach in a biologically relevant manner. The presented results advance the current knowledge on the capabilities of s-SNOM to extract quantitative information with nanoscale resolution from optical data sets with biological application.