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Archives of Toxicology Aug 2023Mutagenicity testing is an essential component of health safety assessment. Duplex Sequencing (DS), an emerging high-accuracy DNA sequencing technology, may provide...
Mutagenicity testing is an essential component of health safety assessment. Duplex Sequencing (DS), an emerging high-accuracy DNA sequencing technology, may provide substantial advantages over conventional mutagenicity assays. DS could be used to eliminate reliance on standalone reporter assays and provide mechanistic information alongside mutation frequency (MF) data. However, the performance of DS must be thoroughly assessed before it can be routinely implemented for standard testing. We used DS to study spontaneous and procarbazine (PRC)-induced mutations in the bone marrow (BM) of MutaMouse males across a panel of 20 diverse genomic targets. Mice were exposed to 0, 6.25, 12.5, or 25 mg/kg-bw/day for 28 days by oral gavage and BM sampled 42 days post-exposure. Results were compared with those obtained using the conventional lacZ viral plaque assay on the same samples. DS detected significant increases in mutation frequencies and changes to mutation spectra at all PRC doses. Low intra-group variability within DS samples allowed for detection of increases at lower doses than the lacZ assay. While the lacZ assay initially yielded a higher fold-change in mutant frequency than DS, inclusion of clonal mutations in DS mutation frequencies reduced this discrepancy. Power analyses suggested that three animals per dose group and 500 million duplex base pairs per sample is sufficient to detect a 1.5-fold increase in mutations with > 80% power. Overall, we demonstrate several advantages of DS over classical mutagenicity assays and provide data to support efforts to identify optimal study designs for the application of DS as a regulatory test.
Topics: Male; Mice; Animals; Procarbazine; Mutation Rate; Bone Marrow; Mutagens; Mutation; Mutagenicity Tests; Mice, Transgenic; Lac Operon
PubMed: 37341741
DOI: 10.1007/s00204-023-03527-y -
Journal of Nippon Medical School =... Sep 2023Intracranial tumors are rare in persons with Down syndrome. Although germ cell tumors and gliomas have been reported in Down syndrome, primary central nervous system...
Intracranial tumors are rare in persons with Down syndrome. Although germ cell tumors and gliomas have been reported in Down syndrome, primary central nervous system lymphoma (PCNSL) has not. We report a case of PCNSL in a 48-year-old man with Down syndrome and no history of malignant tumors. He visited our hospital for evaluation of left hemiparesis and gait disturbance. A thorough examination revealed brain tumors, and analysis of a biopsy specimen of the tumor confirmed a diagnosis of PCNSL. The final pathological diagnosis was diffuse large B-cell lymphoma of the central nervous system. Chemotherapy with rituximab, methotrexate, procarbazine, and vincristine was administered, and whole-brain irradiation was planned in conjunction with chemotherapy. It is unclear whether chromosomal abnormalities related to Down syndrome were involved in the development of PCNSL. Further molecular biological analysis may clarify the mechanism of combined Down syndrome and PCNSL.
Topics: Male; Humans; Middle Aged; Down Syndrome; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Lymphoma, Large B-Cell, Diffuse; Central Nervous System; Central Nervous System Neoplasms
PubMed: 35644559
DOI: 10.1272/jnms.JNMS.2023_90-502