A series of phosphorus porphyrin complexes ([(RO)2P(tpp)]Cl, tpp = tetraphenylporphyrinato group, R = -(CH2CH2O)m(CH2)nH; 1a: m = 2, n = 2; 1b: m = 2, n = 4; 1c: m = 2, n = 6; 1d: m = 3, n = 6) were used for the photodynamic therapy (PDT) of human biliary cancer cell line (NOZ) when exposed to the irradiation of light emitting diodes (LEDs). A Dulbecco's modified Eagle's medium (DMEM) containing NOZ cells (2000 cell well(-1)) and 1 (0-100 nM) was introduced into a 96-well microplate and incubated for 24 h to accumulate 1 into the NOZ cells and to multiply the NOZ cells until the cell number reached 10(4) cells well(-1). After replacing the DMEM medium containing 1 with a fresh DMEM medium without 1, the plates were irradiated for 30 min at 610 nm. After incubation was performed for 24 h in dark conditions, the cell viability of the NOZ cells was determined using the MTT assay. The half maximuminhibitory concentrations 50 (IC50) of 1a-1d were found to be in the range of 33.7-58.7 nM for NOZ. These IC50 values for the NOZ were one hundredth the IC50 value (7.57 μM) for mono-l-aspartyl chlorin e6 (laserphyrin®). Thus, it was found that the PDT activity of 1a-1d was much higher than the mono-l-aspartyl chlorin e6. Similarly, IC50 vales of 1a-1d for HeLa cells were found to be 27.8-52.5 nM. This showed that 1a-1d had high photodynamic activity in cancer cells. At the same time, it was speculated that an LED is a useful light source for deactivating the cancer cells because it can excite the sensitizers with peak width in their absorption spectra using the light of the specified wave length with band width of 10-20 nm; LEDs provide a homogeneous light distribution for the target cells.

OBJECTIVES:Diets that induce a high glycemic response might increase the risk of biliary tract cancer (BTC). We evaluated the hypothesis that diets with high glycemic load (GL) and high glycemic index (GI), which are measures of the glycemic effect of foods, are associated with an increased incidence of BTC.

METHODS:We used data from a population-based prospective study of 76,014 Swedish adults (age 45-83 years; 57% men) who were free of cancer and had completed a food-frequency questionnaire in the autumn of 1997. Incident cancer cases were ascertained by linkage with the Swedish Cancer Registry. Data were analyzed using Cox proportional hazards regression models.

RESULTS:During a mean follow-up of 13.3 years (1,010,777 person-years), we identified 140 extrahepatic BTC cases (including 77 gallbladder cancers) and 23 intrahepatic BTC cases. A high dietary GL was associated with an increased risk of BTC. The multivariable relative risks for the highest versus lowest quartile of dietary GL were 1.63 (95% confidence interval (95% CI), 1.01-2.63) for extrahepatic BTC, 2.14 (95% CI, 1.06-4.33) for gallbladder cancer, and 3.46 (95% CI, 1.22-9.84) for intrahepatic BTC. Dietary GI was statistically significantly positively associated with risk of extrahepatic BTC and gallbladder cancer. We observed no statistically significant association between carbohydrate intake and BTC risk, although all associations were positive.

CONCLUSION:Although these data do not prove a causal relationship, they are consistent with the hypothesis that high-GL and high-GI diets are associated with an increased risk of BTC.