Elucidation of composition of chlorine compounds in acidic sodium chlorite solution using ion chromatography.

With the spread of coronavirus infections, the demand for disinfectants, such as a sodium chlorite solution, has increased worldwide. Sodium chlorite solution is a food additive and is used in a wide range of applications. There is evidence that chlorous acid or sodium chlorite is effective against various bacteria, but the actual mechanism is not well understood. One reason for this is that the composition of chlorine-based compounds contained in sodium chlorite solutions has not been clearly elucidated. The composition can vary greatly with pH. In addition, the conventional iodometric titration method, the N,N-diethyl-p-phenylenediamine sulfate (DPD) method and the absorption photometric method cannot clarify the composition. In this study, we attempted to elucidate the composition of a sodium chlorite solution using absorption spectrophotometry and ion chromatography (IC). IC is excellent for qualitative and quantitative analysis of trace ions. Through this, we aimed to develop an evaluation method that allows anyone to easily determine the bactericidal power of sodium chlorite. We found that commercially available sodium chlorite solution is 80% pure, with the remaining 20% potentially containing sodium hypochlorite solution. In addition, when sodium chlorite solution became acidified, its absorption spectrum exhibited a peak at 365 nm. Sodium chlorite solution is normally alkaline, and it cannot be measured by the DPD method, which is only applicable under acidic conditions. The presence of a peak at 365 nm indicates that the acidic sodium chlorite solution contains species with oxidizing power. On the other hand, the IC analysis showed a gradual decrease in chlorite ions in the acidic sodium chlorite solution. These results indicate that chlorite ions may not react with this DPD reagent, and other oxidizing species may be present in the acidic sodium chlorite solution. In summary, when a sodium chlorite solution becomes acidic, chlorine-based oxidizing species produce an absorption peak at 365 nm. Sodium hypochlorite and sodium chlorite solutions have completely different IC peak profiles. Although there are still many problems to be solved, we believe that the use of IC will facilitate the elucidation of the composition of sodium chlorite solution and its sterilization mechanism.

BSND is a Novel Immunohistochemical Marker for Oncocytic Salivary Gland Tumors.

BSND protein, which is involved in chloride transport, is expressed in normal kidney and the inner ear and is known as an immunohistochemical marker for chromophobe renal cell carcinoma (RCC) and renal oncocytoma; however, other organs and tumor types exhibiting BSND expression have not yet been reported. In this study, we investigated the expression of BSND using data from the Cancer Genome Atlas (TCGA) database and by performing immunohistochemical analyses. As a result, we found that BSND was also expressed in the striated duct cells of normal salivary glands. Next, BSND expression was examined immunohistochemically in 7 types of salivary gland tumors, and BSND positivity was found in Warthin's tumor (25 out of 25 cases; 100%) and oncocytoma (4/4; 100%), both of which are usually classified as oncocytic tumors, whereas BSND negativity was observed for pleomorphic adenoma (0/11), adenoid cystic carcinoma (0/7), acinic cell carcinoma (0/6), mucoepidermoid carcinoma (0/6), and salivary duct carcinoma (0/5). Finally, the expression of BSND mRNA in 30 types of tumors other than chromophobe RCC and salivary gland tumors was examined using data from the TCGA database, but none of these tumors exhibited BSND expression. These results suggest that BSND is expressed only in normal salivary glands and oncocytic salivary gland tumors such as Warthin's tumor and oncocytoma in addition to the two known organs and the two known renal tumor types mentioned above. The selective expression pattern of BSND suggests that BSND is an excellent novel immunohistochemical marker for oncocytic salivary gland tumors.