[Laboratory Performance Study of the Japanese Official Method to Detect Genetically Modified Papaya Line PRSV-YK].

Since the establishment of procedures for the safety assessment of food products that use recombinant DNA technology, the manufacture, import, and sale of genetically modified (GM) foods that have not undergone safety assessment are prohibited under the Food Sanitation Act. Therefore, a performance study to confirm the GM food testing operations of each laboratory is very important to ensure the reliability of the GM food monitoring system. In 2022, GM papaya line PRSV-YK-which has not yet been authorized in Japan-was selected for testing, and a papaya paste and a DNA solution were used as the test samples. With these samples, a laboratory performance study of the DNA extraction and real-time PCR operations was conducted. This confirmed that the 18 participating laboratories were generally performing the DNA extraction and real-time PCR operations correctly. However, some laboratories using certain DNA amplification reagent with some real-time PCR instruments were not able to determine the PRSV-YK detection test. This suggests that the PRSV-YK detection test may not be able to correctly detect samples containing GM papaya when performed with these combinations of instruments and reagent. In order to ensure the reliability of the PRSV-YK detection test, it is necessary to examine in detail how the combination of DNA polymerase reagents and real-time PCR instruments affects the detection limit, and to implement an appropriate solution.

[Proficiency Testing Schemes for Food Nutrition Analysis in Japan (2017-2018)].

This paper deals with proficiency testing schemes for food nutrition analysis in Japan. In schemes in 2017 and 2018, 65 and 73 organizations participated, respectively, and more than 70% of the participants were public organizations responsible for a nutrition-labeling compliance test. The food matrices were pork and chicken sausages, and analytes were protein, fat, ash, moisture, carbohydrate, energy, sodium, salt equivalent, calcium (2018 only), and iron (2018 only). The organizations reporting inadequate laboratory values in one or more nutrients for mandatory declaration (energy, protein, fat, carbohydrate, or salt equivalent) were 11 and 15% of all organizations and 9 and 13% of public organizations in the 2017 and 2018 schemes, respectively. The approximate relative standard deviations for proficiency assessment (RSDr) were as follows: protein, 2%; fat, 3%; ash, 2%; moisture, 0.5%; carbohydrate, 9%; energy, 1%; sodium (salt equivalent), 4%; calcium, 7%; and iron, 7%. Notably, the large RSDr value for carbohydrate may cause inconsistency among laboratories in compliance tests for foods containing several grams or less of carbohydrate per 100 grams.

Tracheal instillation of diesel exhaust particles component causes blood and pulmonary neutrophilia and enhances myocardial oxidative stress in mice.

The influences of inhaling particulate air-pollutants on hematopoiesis and myocardial oxidative stress were investigated in mice by intratracheal instillation (IT) of diesel exhaust particles (DEP), its dichloromethane soluble-component (DMSC) or residual particle-component (RPC). After IT, time courses of cytokine levels in bronchial alveolar lavage fluid (BALF), peripheral blood cell count, myocardial myeloperoxidase (MPO) activity and myocardial chemokine levels were observed for 24 hr. RPC caused sustained blood neutrophilia while that caused by DEP and DMSC was transient. RPC also caused sustained elevations of granulocyte colony-stimulating factor (G-CSF) and interleukin (IL)-6 levels in BALF. Furthermore, IL-1beta level in BALF in the RPC group was significantly elevated at 24 hr after IT. Significant positive correlations were observed between blood neutrophil count and IL-6/G-CSF levels in BALF. MPO activity in the myocardium was increased by RPC at 12 and 24 hr after IT while the activities in the kidney and the liver were not affected. Significant correlation was also observed between myocardial MPO activity and blood neutrophil count at 12 hr after IT, for all three substances. From these results, it was concluded that particle component of DEP may enhance myocardial oxidative stress via blood neutrophilia and the elevation of cytokine levels in BALF.