Development of LD 3 Wavelength Pulsed Laser for PDD and PDT

A new LD (Laser Diode) was developed to specifically excite protoporphyrin IX (PpIX), a photochemotherapeutic agent that is selectively produced in human tumor tissues following administration of 5- aminolevulinic acid (5-ALA), as well as its photoproduct. PpIX emits red fluorescence if it is exposed by the blue light (410 nm) of the laser. During fluorescent diagnosis, the 2 wavelengths of red excitation (635 and 665 nm) from the LD laser were both exposed to the tumor at the same time. Both wavelengths were effectively absorbance matched for the PpIX and the photoproduct produced during irradiation. There is an overlap in the spectral characteristics of the PpIX absorbance and emission. Both processes occur at 635 nm. As such, a continuous wave laser cannot excite PpIX and monitor its emission simultaneously. We therefore developed a pulsed CW laser that could time gate between the blue and red lights, enabling us to both excite and monitor the PpIX at the same time. In future, this laser will be used in a risk assessment protocol for the treatment of elderly patients and to also assess the relative cost this treatment in comparison with other cancer treatments

Raman Study on Lipid Droplets in Hepatic Cells Co-Cultured with Fatty Acids

The purpose of the present study was to investigate molecular compositions of lipid droplets changing in live hepatic cells stimulated with major fatty acids in the human body, i.e., palmitic, stearic, oleic, and linoleic acids. HepG2 cells were used as the model hepatic cells. Morphological changes of lipid droplets were observed by optical microscopy and transmission electron microscopy (TEM) during co-cultivation with fatty acids up to 5 days. The compositional changes in the fatty chains included in the lipid droplets were analyzed via Raman spectroscopy and chemometrics. The growth curves of the cells indicated that palmitic, stearic, and linoleic acids induced cell death in HepG2 cells, but oleic acid did not. Microscopic observations suggested that the rates of fat accumulation were high for oleic and linoleic acids, but low for palmitic and stearic acids. Raman analysis indicated that linoleic fatty chains taken into the cells are modified into oleic fatty chains. These results suggest that the signaling pathway of cell death is independent of fat stimulations. Moreover, these results suggest that hepatic cells have a high affinity for linoleic acid, but linoleic acid induces cell death in these cells. This may be one of the causes of inflammation in nonalcoholic fatty liver disease (NAFLD)