Individual Keratinocyte Necroses in the Epidermis Are Apoptotic Keratinocytes in the Skin.

The patient was a 44-year-old woman with Stevens-Johnson syndrome due to receiving Baktar® (sulfamethoxazole trimethoprim) medication at our outpatient dermatology clinic. The epidermis, dermis, and subcutaneous adipose tissue samples showed numerous necrotic keratinocytes in the epidermis. Apoptotic nuclei were visualized as diaminobenzidine brown deposits with immunoperoxidase staining for cleaved caspase-3. The cleaved caspase-3-positive findings were consistent with eosinophilic material that appeared to be necrotic cells within the epidermis. Therefore, these eosinophilic materials may be apoptotic bodies. Generally speaking, eosinophilic cells are considered necrotic keratinocytes, especially in Japan. To the best of our knowledge, no studies have used apoptotic immunohistochemical markers to examine whether these structures are apoptotic in a human specimen.

A new mechanism for reduced cell adhesion: Adsorption dynamics of collagen on a nanoporous gold surface.

Nanostructured materials such as nanoparticles and nanoporous materials strongly affect cell behaviors such as cell viability. Because cellular uptake of nanoporous materials does not occur, mechanisms for the effects of nanoporous materials on cells are different from those of nanoparticles. The effects of nanoporous materials on cells are thought to result from large conformational changes in the extracellular matrix (ECM) induced by the nanoporous materials, although the mechanotransduction and the critical focal adhesion cluster size also have an effect on the cell response. However, we show that the adhesion of mesenchymal stem cells to a gold surface is reduced for nanoporous gold (NPG), despite the conformational changes in collagen induced by NPG being below the detection limits of the experimental analyses. The adsorption dynamics of collagen on NPG are investigated by molecular dynamics simulations to determine the origin of the reduced cell adhesion to NPG. The adsorption energy of collagen on NPG is lower than that on flat gold (FG) despite there being little difference between the global conformation of collagen segments adsorbed on NPG compared with FG. This finding is related to the surface strain of NPG and the limited movement of collagen amino acids owing to interchain hydrogen bonds. The results obtained in this study provide new insight into the interactions between nanostructured materials and the ECM.