Mutability of mononucleotide repeats, not oxidative stress, explains the discrepancy between laboratory-accumulated mutations and the natural allele-frequency spectrum in C. elegans.

Important clues about natural selection can be gleaned from discrepancies between the properties of segregating genetic variants and of mutations accumulated experimentally under minimal selection, provided the mutational process is the same in the laboratory as in nature. The base-substitution spectrum differs between C. elegans laboratory mutation accumulation (MA) experiments and the standing site-frequency spectrum, which has been argued to be in part owing to increased oxidative stress in the laboratory environment. Using genome sequence data from C. elegans MA lines carrying a mutation (mev-1) that increases the cellular titer of reactive oxygen species (ROS), leading to increased oxidative stress, we find the base-substitution spectrum is similar between mev-1, its wild-type progenitor (N2), and another set of MA lines derived from a different wild strain (PB306). Conversely, the rate of short insertions is greater in mev-1, consistent with studies in other organisms in which environmental stress increased the rate of insertion-deletion mutations. Further, the mutational properties of mononucleotide repeats in all strains are different from those of nonmononucleotide sequence, both for indels and base-substitutions, and whereas the nonmononucleotide spectra are fairly similar between MA lines and wild isolates, the mononucleotide spectra are very different, with a greater frequency of A:T → T:A transversions and an increased proportion of ±1-bp indels. The discrepancy in mutational spectra between laboratory MA experiments and natural variation is likely owing to a consistent (but unknown) effect of the laboratory environment that manifests itself via different modes of mutability and/or repair at mononucleotide loci.

Eosinophilic and neutrophilic leukemoid reaction in a woman with spindle cell sarcoma: a case report.

INTRODUCTION: We report a case of a patient with marked eosinophilia and neutrophilia as a manifestation of a spindle cell sarcoma. CASE PRESENTATION: A 41-year-old African American woman presented with an enlarging, painful mass in her right knee area. Four years previously, she had had a mass similar to this diagnosed as an osteosarcoma, and had undergone a radical resection and hinge-knee replacement. Before the surgery, she was treated with neoadjuvant docetaxel and gemcitabine. A biopsy was taken from the recurrent mass, and histological examination revealed high-grade soft-tissue sarcoma. The patient received no further treatment. Complete blood counts revealed a white blood cell (WBC) count of 13.6 to 17.9 × 109/L, with neutrophils being 8.2 to 10.9 × 109/L and eosinophils 1.8 to 1.9 × 109/L. At readmission six months later, WBC was 126.7 × 109/L, with neutrophils being 57.02 × 109/L and eosinophils 60.82 × 109/L. The eosinophils peaked at 77.79 × 109/L two days later. Evaluations for allergies, infection, and autoimmune mechanisms were negative. Bone marrow revealed increased eosinophils without blasts. After resection, blood counts abruptly decreased to the normal range. Pathology confirmed high-grade spindle cell sarcoma. Approximately one year after resection, the patient was readmitted with metastatic disease to her lungs. During this presentation, her eosinophil and neutrophil count was again increased. WBC was 107.8 × 109/L, with eosinophil count of 47.43 × 109/L and neutrophil count of 44.10 × 109/L. Interleukin-5 was normal, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was elevated at 208.8 (normal < 4.8). CONCLUSION: In our case, the patient had eosinophilia and neutrophilia associated with a spindle cell sarcoma, possibly representing a paraneoplastic syndrome secondary to GM-CSF. There were no signs of infectious, allergic, or autoimmune causes for the eosinophilia or neutrophilia. Even though the occurrence of eosinophilia and neutrophilia with malignancy is rare, patients who have either condition without an apparent cause should be checked for malignancy.