In order to clarify the mechanism of photo-damage caused by eugenol (4-allyl-2-methoxyphenol), we measured cell survival in the presence of eugenol at concentrations of 10
−3–10
−7
m, with and ...without VL (visible light) irradiation by a VL dental lamp and at various pHs (7.2, 7.8 and 8.2) using two different cells (HSG, a human submandibular gland tumor cell line; HGF, a human gingival fibroblast in primary culture). Also, ROS (reactive oxygen species) generation in the above adherent single cells was measured by ACAS laser cytometry combined with CDFH-DA, a peroxide probe. The survival of both HSG and HGF cells treated with eugenol was significantly decreased as the VL irradiation time and/or the pH of the medium was increased. The amount of ROS generated from eugenol was also enhanced by increasing the VL irradiation time and elevating the pH of the medium. Cytotoxicity and ROS generation of HGF cells were significantly lower than that of HSG cells. Glutathione (1
m
m) or cysteine (1
m
m) protected the photo damages. We conclude that the cytotoxicity of VL-irradiated eugenol possibly was caused by the generation of eugenol radicals and additionally by ROS, both of which were produced dependent on the dose of eugenol, length of irradiation time, and pH of the medium.
To assess gene expression of a membrane-bound G-protein-coupled fatty acid receptor, GPR40, in the human pancreas and islet cell tumors obtained at surgery were analyzed. The mRNA level of the GPR40 ...gene in isolated pancreatic islets was approximately 20-fold higher than that in the pancreas, and the level was comparable to or rather higher than that of the sulfonylurea receptor 1 gene, which is known to be expressed abundantly in human pancreatic β cells. A large amount of GPR40 mRNA was detected in tissue extracts from two cases of insulinoma, whereas the expression was undetectable in glucagonoma or gastrinoma. The present study demonstrates that GPR40 mRNA is expressed predominantly in pancreatic islets in humans and that GPR40 mRNA is expressed solely in human insulinoma among islet cell tumors. These results indicate that GPR40 is probably expressed in pancreatic β cells in the human pancreas.
Ghrelin is a 28-amino acid peptide that regulates GH release together with GHRH and somatostatin. The expression of ghrelin has been detected in the stomach, small intestine, hypothalamus, pituitary ...gland, kidney, placenta, and testis. Recently it was reported that ghrelin is present in pancreatic α-cells and that it stimulates insulin secretion. In this study, we examined the ghrelin expression in two cases of glucagonoma and two cases of insulinoma by Northern blot analysis and immunohistochemistry. Ghrelin expression was identified in a case of glucagonoma associated with multiple endocrine neoplasm type I both by Northern blot analysis using total RNA and by immunohistochemistry, although the plasma ghrelin level was not elevated. This is the first case of tumor in which ghrelin gene expression was detected by Northern blot analysis using total RNA.
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