Synthesis of novel crownophanes containing two phenolic moieties via a tandem claisen rearrangement

A series of crownophanes containing two phenolic moieties within a macrocyclic ring have been successfully synthesized by a one-step thermal reaction from the corresponding macrocyclic polyethers by using a “Tandem Claisen Rearrangement”.     

Total synthesis of antibiotic streptothricin F

The first total synthesis of streptothricin F was achieved and its structure was unequivocally confirmed.     

Routing Problems on the Mesh of Buses

The mesh of buses (MBUSs) is a parallel computation model which consists ofn×nprocessors,nrow buses, andncolumn buses, but no local connections between neighboring processors. Annlower bound for the permutation routing on this model is shown. The proof does not depend on common predetermined assumptions such as “if a packet has to move horizontally then it has to ride on a horizontal bus at least once.” As for upper bounds, a 1.5nalgorithm is shown.     

Synthesis of 4-o-(N-acetyl-β-D-glucosaminyl)-6-o-acyl-N-acetylmuramyl-L-alanyl-D-isoglutamine

Long-chain acyl derivatives of the disaccharide dipeptide, which is a common building unit of bacterial cell walls, were synthesized in order to test their immunostimulating activity.     

Thrombocytogenesis by megakaryocyte; Interpretation by protoplatelet hypothesis

Serial transmission electron microscopy of human megakaryocytes (MKs) revealed their polyploidization and gradual maturation through consecutive transition in characteristics of various organelles and others. At the beginning of differentiation, MK with ploidy 32N, e.g., has 16 centrosomes in the cell center surrounded by 32N nucleus. Each bundle of microtubules (MTs) emanated from the respective centrosome supports and organizes 16 equally volumed cytoplasmic compartments which together compose one single 32N MK. During the differentiation, single centriole separated from the centriole pair, i.e., centrosome, migrates to the most periphery of the cell through MT bundle, corresponding to a half of the interphase array originated from one centrosome, supporting one "putative cytoplasmic compartment" (PCC). Platelet demarcation membrane (DM) is constructed on the boundary surface between neighbouring PCCs. Matured PCC, composing of a tandem array of platelet territories covered by a sheet of DM is designated as protoplatelet. Eventually, the rupture of MK results in release of platelets from protoplatelets. (Communicated by Tadamitsu Kishimoto, M.J.A.).