No abstract

Aberrant sialylation and altered sialyltransferase (ST) expressions are frequently found in many types of cancer. In this study, we examined the expressions of α 2,3-linked sialic acid residues and STs mRNA in human gastric cancer tissues. The relationship between the levels of α 2,3-linked sialic acid residues and the expression of STs mRNA was also analyzed. Maackia amurensis leukoagglutinin (MAL) specific for α 2,3-linked sialic acid was used for immunohistochemical staining. All gastric cancer tissues were positive for MAL staining, whereas adjacent normal tissues were negative. The extent of MAL staining was significantly correlated with the behavior of gastric cancer. The expression of STs mRNA was examined by real-time quantitative reverse transcription-polymerase chain reaction assay. The levels of ST3Gal IV and ST6GalI in gastric cancer tissues were significantly increased compared with those in adjacent normal tissues (P < 0.05), whereas the levels of ST3Gal I, ST3Gal III, and ST3Gal VI were not increased. Furthermore, the high expression of ST3Gal IV was closely related to the extent of MAL staining (P < 0.05) unlike that of ST6Gal I. These results indicated that gastric cancer tissues expressed high levels of α 2,3-linked sialic acid residues, ST3Gal IV, and ST6Gal I. The high expression of ST3Gal IV may contribute to the expression of α 2,3-linked sialic acid residues, which is associated with the malignant behavior of gastric cancer cells.

A visible-light-induced denitrogenative phosphorylation of benzotriazoles is presented, in which diverse substituted aryl phosphonates could be obtained in good to excellent yields. This efficient protocol exhibits good tolerance with various functional groups. Furthermore, the utility of this photochemical protocol is demonstrated by a gram-scale reaction, and a reasonable mechanism is proposed.

The one-step synthetic strategy for the preparation of the hitherto unknown calix[3]carbazole from readily available starting materials is described. Calix[3]carbazole is obtained in 20% yield, and it could selectively bind the N(C2H5)4(+) cation (tetraethylammonium, TEA) via cation-π interactions. The experimental and modeling results indicate that calix[3]carbazole possesses a larger π-cavity as well as a better chromophoric property than the traditional phenol-based macrocycles, and thus is capable of binding to and optically responding to the relatively large guest TEA.

No abstract