Masao Teramoto

Induction of basic helix-loop-helix protein DEC1 (BHLHB2)/Stra13/Sharp2 in response to the cyclic adenosine monophosphate pathway.

DEC1 (BHLHB2)/Stra13/Sharp2, a basic helix-loop-helix (bHLH) transcription factor has been suggested to be involved in the control of proliferation and/or differentiation of several cells including nerve cells, fibroblasts and chondrocytes. In the present study, we examined the effect of parathyroid hormone (PTH), dibutyryl cAMP (Bt2cAMP) and forskolin on the expression of DEC1 in various cells. In rabbit chondrocyte cultures, PTH or Bt2cAMP increased the DEC1 mRNA level within 1 h. Thereafter, the DEC1 mRNA level rapidly decreased to the basal level at 3 h, and increased at 6-24 h. In cultures of a mouse embryo prechondrogenic cell line ATDC5, PTH or forskolin, an activator of adenylate cyclase, also increased the DEC1 mRNA level within 1 h. Furthermore, in all evaluated cell lines of human fibroblasts, canine epithelial cells, human carcinoma, human glioblastoma and human melanoma, Bt2cAMP increased the DEC1 mRNA level within 1-3 h. Studies with actinomycin D and cycloheximide indicated that the enhancement of DEC1 mRNA by cAMP was not due to mRNA stabilization and did not require new protein synthesis. These findings suggest that DEC1 is a novel direct target for cAMP in wide types of cells, and that the bHLH protein is involved in the control of gene expression in cAMP-activated cells.

Membrane-bound transferrin-like protein (MTf): structure, evolution and selective expression during chondrogenic differentiation of mouse embryonic cells

Mouse membrane-bound transferrin-like protein (MTf) cDNA was cloned to examine its expression during chondrogenic differentiation in the mouse embryonic cell line ATDC5, and to analyze the phylogenetic relationships among the MTfs of four animal species and 23 other transferrin members. Phylogenetic analysis indicated that the MTf gene diverged from the common ancestor gene earlier than the genes of the other transferrins such as serum transferrin, lactoferrin and ovotransferrin, and that the divergence occurred after the divergence of vertebrates and invertebrates. MTf, as well as the other transferrins, consists of two repeated domains. The similarity between the N-terminal and the C-terminal domains of MTf is much higher than that of the other transferrins, although the five amino acid residues required for iron binding were not conserved in the C-terminal domain of MTf in contrast to the conservation of these residues in both domains of the other transferrins. Among various adult mouse tissues, MTf mRNA was expressed at the highest level in cartilage and at a moderate level in the testis. MTf mRNA was expressed only at very low levels in the brain, spleen, thymus, muscle, lung, skin and intestine, and hardly detected in the heart, kidney, stomach and liver. In cultures of the mouse ATDC5 cell line, MTf is developmentally expressed in parallel with the expression of type II collagen and aggrecan, in the pattern commensurate with the onset of chondrogenesis to form cartilage nodules. The structural characteristics and the expression pattern suggest that during development and in adult tissues, MTf has some functions that are different from those of other transferrins.

The Device of the Operation that Used Wiring Together for Intertrochanteric Fractures and Subtrochanteric Femoral Fractures

【目的】大腿骨転子部及び転子下骨折に対する内固定法の発展によりその成績は飛躍的に向上したが，まれにカットアウト等の合併症が出現する．その原因は主に整復不良，ラグスクリュー挿入位置不良である．我々は閉鎖的整復不良な症例に対しては積極的に観血的整復を行っている．整復位を鋼線締結で保持しCHSあるいはγネイルで内固定することで術後内反変形やカットアウトを防ぐことができた症例を報告し，その適応について考察する．【対象と方法】鋼線締結を併用しCHSあるいはγネイルを行った大腿骨転子部及び転子下骨折の10例である．平均年齢は76.7歳だった．骨折型をAO分類で分類した．【結果】全例でカットアウト等の合併症なく骨癒合した．荷重までの期間は平均23.5日だった．【結語】閉鎖的整復不良な症例に対しては内固定材の固定力を過信することなく観血的整復を行い，正確な整復位での内固定を目指すことで良好な成績が期待できる．