Training echo state networks for rotation-invariant bone marrow cell classification

The main principle of diagnostic pathology is the reliable interpretation of individual cells in context of the tissue architecture. Especially a confident examination of bone marrow specimen is dependent on a valid classification of myeloid cells. In this work, we propose a novel rotation-invariant learning scheme for multi-class echo state networks (ESNs), which achieves very high performance in automated bone marrow cell classification. Based on representing static images as temporal sequence of rotations, we show how ESNs robustly recognize cells of arbitrary rotations by taking advantage of their short-term memory capacity. The performance of our approach is compared to a classification random forest that learns rotation-invariance in a conventional way by exhaustively training on multiple rotations of individual samples. The methods were evaluated on a human bone marrow image database consisting of granulopoietic and erythropoietic cells in different maturation stages. Our ESN approach to cell classification does not rely on segmentation of cells or manual feature extraction and can therefore directly be applied to image data.

     

15d-PGJ2 Promotes ROS-Dependent Activation of MAPK-Induced Early Apoptosis in Osteosarcoma Cell In Vitro and in an Ex Ovo CAM Assay

Osteosarcoma (OS) is the most common type of bone tumor, and has limited therapy options. 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) has striking anti-tumor effects in various tumors. Here, we investigated molecular mechanisms that mediate anti-tumor effects of 15d-PGJ₂ in different OS cell lines. Human U2-OS and Saos-2 cells were treated with 15d-PGJ₂ and cell survival was measured by MTT assay. Cell proliferation and motility were investigated by scratch assay, the tumorigenic capacity by colony forming assay. Intracellular ROS was estimated by H₂DCFDA. Activation of MAPKs and cytoprotective proteins was detected by immunoblotting. Apoptosis was detected by immunoblotting and Annexin V/PI staining. The ex ovo CAM model was used to study growth capability of grafted 15d-PGJ₂-treated OS cells, followed by immunohistochemistry with hematoxylin/eosin and Ki-67. 15d-PGJ₂ substantially decreased cell viability, colony formation and wound closure capability of OS cells. Non-malignant human osteoblast was less affected by 15d-PGJ₂. 15d-PGJ₂ induced rapid intracellular ROS production and time-dependent activation of MAPKs (pERK1/2, pJNK and pp38). Tempol efficiently inhibited 15d-PGJ₂-induced ERK1/2 activation, while N-acetylcystein and pyrrolidine dithiocarbamate were less effective. Early but weak activation of cytoprotective proteins was overrun by induction of apoptosis. A structural analogue, 9,10-dihydro-15d-PGJ₂, did not show toxic effects in OS cells. In the CAM model, we grafted OS tumors with U2-OS, Saos-2 and MG-63 cells. 15d-PGJ₂ treatment resulted in significant growth inhibition, diminished tumor tissue density, and reduced tumor cell proliferation for all cell lines. Our in vitro and CAM data suggest 15d-PGJ₂ as a promising natural compound to interfere with OS tumor growth.