During the investigation of an outbreak of diarrhea in suckling rats, a virus morphologically identical to but antigenically distinct from rotaviruses was identified. The disease was characterized clinically by erythema and cracking and bleeding of the perianal skin associated with the excretion of poorly formed fecal pellets, liquid, and gas. Light microscopy-observable changes consisted of small intestinal villous atrophy, villous epithelial necrosis, and villous epithelial syncytial cell formation. The cytoplasm of the epithelial syncytial cells contained large numbers of 80-nm viral particles that were often associated with reticular aggregates of electron-dense material. Viral infection principally involved the luminal one-fourth to one-third of the intestinal villi as determined by indirect immunofluorescence. This rotavirus-like agent contained 11 double-stranded RNA segments; however, the migration pattern of these segments in polyacrylamide gels differed from the electrophoretic pattern which is characteristic of the typical rotaviruses. The agent had a buoyant density in CsCl of 1.36 to 1.4 g/cm3 and was labile at pH 3 and at 56°C; however, infectivity of viral inocula was not altered by extensive treatment with ether or by pH 5 buffers. This disease, which we have named infectious diarrhea of infant rats, is the first recognized viral diarrhea of rats and appears to be a good model for the study of the recently recognized group of atypical rotaviruses.

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Mastocytosis KIT D816V AML Microdissection A B S T R A C TThe KIT mutation D816V is associated with autonomous growth of mast cells (MC) and is detectable in most patients with systemic mastocytosis (SM), including cases with associated hematologic non-MC-lineage disease (AHNMD). Recently, KIT D816V was reported to be expressed in patients with acute myeloid leukemia (AML). However, it was not clarified whether these patients have co-existing occult SM. We investigated neoplastic cells in 101 patients with AML for expression of KIT D816V. In 7/101 patients (6.9%), KIT D816V was detectable. After a thorough histologic, molecular, and biochemical analysis, all 7 cases were found to have an associated SM, leading to the final diagnosis SM-AML. Microdissected tryptaseþ MC displayed KIT D816V in all patients tested, whereas CD34þ blasts exhibited KIT D816V in only 2/4 patients. In one AML patient, SM without KIT D816V was detected.In all other patients, no associated SM was found, and leukemic blasts were negative for KIT D816V. In summary, our data show that KIT D816V in AML is highly associated with co-existing SM (SM-AML). Moreover, our data show that AML blasts may lack this transforming target-mutant, which may be important when considering the use of KIT D816V-targeting drugs for treatment of patients with KIT D816V-positive AML.ª 2010 Federation of European Biochemical Societies.Published by Elsevier B.V. All rights reserved. IntroductionAcute myeloid leukemia (AML) is a life-threatening hematopoi- E-mail address: peter.valent@meduniwien.ac.at (P. Valent). Abbreviations: AML, acute myeloid leukemia; ASM, aggressive systemic mastocytosis; BM, bone marrow; CMML, chronic myelomonocytic leukemia; FAB, FrencheAmericaneBritish; FCS, fetal calf serum; MC, mast cell(s); MCL, mast cell leukemia; PB, peripheral blood; PBS, phosphate-buffered saline; RFLP, restriction fragment length polymorphism; RT, room temperature; SCF, stem cell factor; SM, systemic mastocytosis; TK, tyrosine kinase.

Protease activated receptor-2 (PAR-2) is the receptor for the prototype mast cell product tryptase. PAR-2 expression by cells of the human germinal epithelium was reported, but the exact cellular sites of testicular expression remained unknown. That became of interest, because mast cells, expressing tryptase, were found in the walls of seminiferous tubules of patients suffering from sub-and infertility. This location suggested that mast cells via tryptase might be able to influence PAR-2-expressing cells in the germinal epi-thelium. To explore these points, we used testicular paraffin-embedded sections for immunohistochemistry. PAR-2-positive cells were mostly basally located cells of the seminiferous epithelium, namely spermatogonia. Some stained for the receptor for GDNF (GFRalpha-1), and possibly represent spermatogonial stem cells (SSCs). As true human SSCs could not be examined, we turned to TCam-2 seminoma cells, expressing PAR-2 and stem cell markers, including GFRalpha-1. TCam-2 cells robustly responded to stimulation with a specific PAR-2 agonist (SLIGKV) by increased intracellular Ca 2+ levels. Recombinant tryptase and trypsin, but not a control peptide (VKGILS) evoked this response, implying functional PAR-2. Video imaging and caspase 3/7 assays showed that SLIGKV and tryptase prevented spontaneous apoptosis and increased proliferation of TCam-2 cells. The expression of the marker of pluripo-tency OCT3/4 was unchanged upon activation of PAR-2, suggesting that the stem cell-like character is not changed. Furthermore, human germ cell cancers were examined. A subset of seminoma and carcinoma in situ samples expressed PAR-2, indicating that yet unknown subgroups exist. Collectively, the descriptive data obtained in human testicular sections, in germ cell cancers and the functional results in TCam-2 cells imply a trophic role of mast cell-derived tryptase for human germ cells. This may be relevant for sub-types of human germ cell cancers, and possibly SSCs. It also raises the possibility that PAR-2 agonists might be useful for the in vitro propagation of human SSCs.

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