In this study, the authors show an empirical guideline for designing hole transport materials (HTMs) that suppress rises in driving voltage even with a few hundred nanometer thick film in the organic light emitting diodes (OLEDs). In a device structure of indium tin oxide (110nm)/hole transport layer (HTL) (Xnm)∕4,4′-N,N′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (10nm)/tris-(8-hydroxyquinoline)aluminum (Alq3) (50nm)∕MgAg (100nm)∕Ag (10nm), the authors compared electroluminescence characteristics of the OLEDs having a thin-film HTL (X=50nm) and a thick-film HTL (X=300nm) using 13 kinds of HTMs. They observed a closed correlation between suppression of the driving voltage and the HTMs’ thermal characteristics. Highly thermally stable HTMs resulted in a small increase in the driving voltage.

The attraction of leucocytes to allografts is essential for rejection. The process is controlled by chemokines. In order to clarify the role of lymphotactin (a cytokine that represents a novel branch of the chemokine superfamily) in regulating leucocyte trafficking during graft rejection, we used rat renal transplantation models to examine its gene expression and the distribution of lymphotactin-expressing cells in renal grafts. Lymphotactin mRNA was upregulated strongly in acutely rejecting renal allografts. The mRNA was undetectable in isografts, chronically rejecting renal allografts or normal kidney. Once lymphotactin was expressed, large numbers of infiltrating lymphocytes were seen. Moreover extended studies demonstrated that in cultured rat spleen cells the expression of lymphotactin mRNA was markedly induced by phytohaemagglutinin (PHA) or phorbol myristate acetate (PMA), and such induction was inhibited by the immunosuppressive drugs FK506 and cyclosporin. Collectively, these observations provide new evidence demonstrating that lymphotactin is a key regulator of lymphocyte motility and adhesiveness during acute allograft rejection. FK506 and cyclosporin inhibition of lymphotactin expression is likely to represent an important molecular mechanism of the action of the drugs.

Humanpro-urokinase CDNAwas isolated from the CDNAlibrary constructed from human kidney mRNAusing the dC/dG homopo.lymer tailing method and Okayama-Berg method with pBR322as a vector. Amature polypeptide starting with Ser was produced in Escherichia coli under the control of the tac promoter and the Shine-Dalgarno sequence of the catechol 2,3-oxygenase gene derived from Pseudomonas putida. By replacing the sequence coding for N-terminal eight amino acids of pro-urokinase with the synthetic DNAoligomer, the bacterial pro-urokinase had a molecular weight of 47,000 daltons and accounted for 15%of the insoluble fraction of E. coli proteins in induced cells. Its biological activity was restored by renaturing the bacterial product. The activity of bacterial pro-urokinase was 450 IU/ml culture. Plasminogen activators play a role in plasminogen dependent fibrinolysis in a controlling blood clot lysis system. Two types of

The conditioned medium of a HTLV-I-carrying T cell line HUT-102 showed cytotoxic activity against a mouse fibroblast cell line L-M. We prepared the cDNA library from HUT-102 poly(A)+ RNA and screened it using oligonucleotide probes that correspond to the amino acid sequences conserved in tumor necrosis factor (TNF) and lymphotoxin (LT). As a result we obtained two kinds of cDNA clones encoding LT in which amino acid residue 26t of mature LT is different; one is Asn and another is Thr. The sequence of the genomic clones obtained using a polymerase chain reaction method showed that the HUT-102 genome also contains two types of LT genes. Recombinant LTs expressed in Escherichia coli exhibited the same level of cytolytic activity against L-M cells. These results indicate that the cytotoxin constitutively produced by HUT-102 cells include two kinds of LT.

A precursor of salmon calcitonin I (SCT) was produced in Escherichia coli transformed by recombinant plasmids. A double-stranded DNAcoding for SCT-Gly, preceded by ATGand followed by tandem stop codons, was constructed using a combination of chemical synthesis and enzymatic assembly. The gene for the N-terminal portion of metapyrocatechase (C23O) and its preceding ribosome binding site derived from Pseudomonas putida were fused to the synthetic gene. Introduction of this fragment into E. coli resulted in the synthesis of the fusion protein at high efficiency under the control of the tac promoter. After cleavage of the protein with cyanogen bromide, SCT-Gly was purified to homogeneity by gel filtration and by reverse phase chromatography. The structure of the peptide was confirmed by amino acid composition and sequencing analyses. The hypocalcemic activity of the bacterial product was estimated as about one-seventh of that of SCT.