Abstract: Photochemical demethylation reactions in solutions of thiazine dyes, in which the dye molecules act as both sensitizer and substrate, are reduced by quenching triple-state dye molecules, returning them to the unreactive ground state.

Abstract: The location at which tissue samples are obtained to determine whether cells exhibit characeristics associated with cell differentiation or cancer by molecular analysis is determined by topically applying to epithelial tissue a dye that selectively stains cancer and precancerous tissue.

Abstract: In a light-directed method of identifying abnormal mucosal tissue, any suspect sites revealed by a light that selectively aids in visualizing abnormal tissue are marked with a dye facilitate further evaluation of the suspect tissue.

Abstract: Photochemical demethylation reactions in solutions of thiazine dyes, in which the dye molecules act as both sensitizer and substrate, are reduced by quenching triple-state dye molecules, returning them to the unreactive ground state.

Abstract: Methods of detecting progression from precancer to cancer are provided utilizing toluidine blue staining as well as detecting allelic variation at microsatellite loci. An allelic variation in one or more locus is indicative of a progression from precancer to cancer.

Abstract: Photochemical demethylation reactions in solutions of thiazine dyes, in which the dye molecules act as both sensitizer and substrate, are reduced by quenching triple-state dye molecules, returning them to the unreactive ground state.

Abstract: In diagnostic testing for cancer and precancer of the epithelium, the undesired binding of cancer-selective dyes to proteins in the extracellular matrix, which may lead to false positives, is reduced by applying to the epithelium being tested, before application of the dye, a solution of a non-toxic amphiphilic protein in a pharmacolgically acceptable solvent.

Abstract: Compounds having the structural formula (A) wherein X is hydrogen, methyl, or Y; Y is —NH—R or hydrogen; and R is methyl or formula (B) are useful as in vivo stains for the detection of dysplastic tissue.

Abstract: Photochemical demethylation reactions in solutions of thiazine dyes, in which the dye molecules act as both sensitizer and substrate, are reduced by quenching triple-state dye molecules, returning them to the unreactive around state.

Abstract: The location at which tissue samples are obtained to determine whether cells exhibit characeristics associated with cell differentiation or cancer by molecular analysis is determined by topically applying to epithelial tissue a dye that selectively stains cancer and precancerous tissue.

Abstract: A prognostic method for early prediction of eventual development of invasive cancer comprises identifying suspect cancerous and precancerous tissue sites by applying a dye which selectively stains such sites, followed by molecular genetic analysis to determine whether the DNA of such sites exhibits allelic losses for mutation of tumor suppressor genes.

Abstract: A diagnostic method for detecting cancerous epithelial cells by selectively marking the mitochondria of the cancer cells, by delivering to the epithelium a cationic supravital mitochondrial marking agent. Selective killing of cancerous epithelial cells in the presence of normal cells is effected by delivering a cationic supravital mitochondrial marking agent to epithelial cancer cells. The killing agent can also comprise the reaction product of the marking agent and a cancer chemotherapeutic drug.

Abstract: A diagnostic method for detecting cancerous epithelial cells by selectively marking the mitochondria of the cancer cells, by delivering to the epithelium a cationic supravital mitochondrial marking agent. Selective killing of cancerous epithelial cells in the presence of normal cells is effected by delivering a cationic supravital mitochondrial marking agent to epithelial cancer cells.

Abstract: A process for synthesizing 2-amino-5-dimethlyaminophenyl thiosulfonic acid comprises the step of oxidizing N,N′-dimethyl-&rgr;-phenylene-diamine in the presence of a source of thiosulfate ions, while maintaining the temperature of the reaction mixture not higher than about 10° C. This compound is useful as an intermediate in the synthesis of toluidine blue ∘.

Abstract: A process for synthesizing 2-amino-5-dimethlyaminophenyl thiosulfonic acid comprises the step of oxidizing N,N′-dimethyl-&rgr;-phenylene-diamine in the presence of a source of thiosulfate ions, while maintaining the temperature of the reaction mixture not higher than about 10° C. This compound is useful as an intermediate in the synthesis of toluidine blue O. A process for manufacturing toluidine blue O with improved yield, includes the step of preparing the intermediate 2-amino-5-diethylaminopropyl thiosulfonic acid according to the above described procedure.

Abstract: A process for synthesizing 2-amino-5-dimethlyaminophenyl thiosulfonic acid comprises the step of oxidizing N,N′-dimethyl-&rgr;-phenylene-diamine in the presence of a source of thiosulfate ions, while maintaining the temperature of the reaction mixture not higher than about 10° C. This compound is useful as an intermediate in the synthesis of toluidine blue O.

Abstract: A process for synthesizing 2-amino-5-dimethlyaminophenyl thiosulfonic acid comprises the step of oxidizing N,N′-dimethyl-&rgr;-phenylene-diamine in the presence of a source of thiosulfate ions, while maintaining the temperature of the reaction mixture not higher than about 10° C. This compound is useful as an intermediate in the synthesis of toluidine blue O. A process for manufacturing toluidine blue O with improved yield, includes the step of preparing the intermediate 2-amino-5-diethylaminopropyl thiosulfonic acid according to the above described procedure.

Abstract: N-demethylated and N,N-demethylated derivatives of toluidine blue O and compositions which include these derivatives and the conformational isomers of toluidine blue O. Improved methods for the detection of dysplastic oral tissue using such compositions.Processes for synthesis of toluidine blue O products, in which a complexing agent is introduced prior to the last stage of oxidation of a three-step synthesis from N,N-dimethyl-.rho.-phenylenediamine.An HPLC method for characterizing toluidine blue O products in which the mobile phase is an aqueous solution of an organic acid.