Rapid increases in the membrane expression of neutral endopeptidase (CD10), aminopeptidase N (CD13), tyrosine phosphatase (CD45), and Fc gamma-RIII (CD16) upon stimulation of human peripheral leukocytes with human C5a.

Rapid increases in the membrane expression of C3 receptors on granulocytes and monocytes in response to the anaphylatoxin C5a have previously been described. In this study we demonstrate increases in the membrane expression of neutral endopeptidase (NEP, CD10, CALLA), aminopeptidase N (APN, CD13), tyrosine phosphatase (CD45/CD45Ro) and the Fc R Fc gamma-RIII (CD16) on granulocytes within minutes of treatment with human C5a. Monocytes responded to C5a with increases in CD13 and CD45/CD45Ro. These membrane modulations could be prevented by preincubating the C5a preparations with anti-C5a mAb C17/5 but not by pretreating the cells with cycloheximide. Increases of CD10, CD13, and CD11b but not CD11a (LFA-1) were also observed in leukocytes from patients undergoing hemodialysis with cuprophan membranes. The increase of CD16 on granulocytes was dependent on the presence of plasma during in vitro activation with C5a indicating that plasma contains inhibitors which prevent the previously described loss of Fc gamma-RIII upon stimulation of the cells.     

Tumor necrosis factor signal transduction. Tissue-specific serine phosphorylation of a 26-kDa cytosolic protein

Binding of tumor necrosis factor-alpha (TNF-alpha) to its receptor on U937 cells results in rapid and TNF dose-dependent phosphorylation of a cytosolic protein with an apparent molecular mass of 26,000 kDa (p26) and an isoelectric point of 5.6. Half-maximal phosphorylation of p26 was achieved at concentrations of 1.8 ng/ml and was detectable within 20 s of TNF-alpha treatment. p26 is phosphorylated exclusively at serine residues. p26 phosphorylation occurs at 37 degrees C as well as at 14 degrees C, indicating that internalization of the TNF receptor is not required for serine kinase activation. Dephosphorylation of p26 starts 10 min after TNF-induced phosphorylation, suggesting a possible regulatory function of this cytosolic protein within the post-TNF receptor signaling system. p26 is also phosphorylated upon treatment with lymphotoxin. In contrast, both interferon-gamma and lipopolysaccharide fail to induce p26 phosphorylation. Whereas phosphorylated p26 was detected in the TNF-sensitive breast cancer cell line CRL1500, other TNF-responsive tumor cell lines investigated lacked enhanced phosphorylation of p26 in response to TNF, indicating that the 26-kDa phosphoprotein (pp26) may be a cell type-specific second messenger molecule involved in TNF signal transduction in some, but not all, target cells. p26 is also phosphorylated in a subclone of U937 (U937.C27) that responds to TNF-alpha with differentiation, yet is resistant to TNF-alpha-mediated growth inhibition. In contrast, p26 is not phosphorylated in another U937 derivative (U937.G3) that is resistant to both TNF-alpha-induced growth arrest and differentiation, suggesting that pp26 may play a role in the TNF signaling pathway linked to differentiation processes rather than to growth control.     

Inhibition of flower formation by antisense repression of mitochondrial citrate synthase in transgenic potato plants leads to a specific disintegration of the ovary tissues of flowers.

The tricarboxylic acid (TCA) cycle constitutes a major component of the mitochondrial metabolism of eucaryotes, including higher plants. To analyze the importance of this pathway, we down-regulated mitochondrial citrate synthase (mCS; EC 4.1.3.7), the first enzyme of the TCA cycle, in transgenic potato plants using an antisense RNA approach. Several transformants were identified with reduced citrate synthase activity (down to approximately 6% of wild-type activity). These plants were indistinguishable from wild-type plants in the greenhouse during vegetative growth. A major change, however, was seen upon initiation of the generative phase (flower formation). In the case of transgenic plants with a strong reduction in citrate synthase activity (< 30% of wild-type levels), flower buds formed > 2 weeks later as compared with wild-type plants. Furthermore, flower buds from these plants did not develop into mature flowers but rather were aborted at an early stage of development. Microscopic analysis showed that in these cases ovaries disintegrated during flower development. We conclude that the TCA cycle is of major importance during the transition from the vegetative to the generative phase.     

Peptide modification by introduction ofα-trifluoromethyl substituted amino acids

Summary Methodology for the synthesis and incorporation of-trifluoromethyl substituted amino acids into N- and C-terminal position of peptides is described. The incorporation of-trifluoromethyl substituted amino acids into strategical positions of peptides enhances proteolytic stability and lipophilicity. Furthermore, it improves transport rates in vivo and permeability through certain body barriers.     

Thiopyronine sensitized photodynamic effect on ribosome synthesis and ribosome content in saccharomyces cells

Summary The content and the synthesis of membrane bound and free ribosomes in growing yeast cells was investigated after photodynamic treatment of the cells with thiopyronine and visible light. It was shown that the synthesis of ribosomes is inhibited after photodynamic treatment and that as a consequence, the content of ribosomes in the cell is diminished.     

A new progestin (Sa 45.249) for cycle control in pigs communication I: Hormonal activities and dosage

Sa 45.249 was applied for 12 days to groups of ten gilts each. A daily dose of 3, 6, 12 or 24 mg inhibited cyclic functions effectively; estrus was observed 4.5 ± 0.8, 4.8 ± 0.8, 5.2 ± 0.9 and 6.1 ± 0.6 days after cessation of treatment, respectively. All animals were slaughtered 8 days after induced estrus. Only animals treated with 3 mg showed a high incidence of ovarian cysts simultaneously with the occurrence of corpora lutea. In animals treated with higher dosages, only one (6 mg) had 4 cystic follicles, but simultaneously 12 corpora lutea. In another study, the effectiveness of Sa 45.249, applied at different doses, for differing time periods, and starting at different days of the cycle, was investigated. Doses ranged from 3 to 9 mg/day, duration of treatment from 8 to 16 days and treatments commenced on days 2, 5, 10, 15 or 19 of the cycle. An increase in the daily doses of 1 mg resulted in a delay of estrus of less than 0.1 day. Of 99 gilts, 93 showed an estrus 6.5 ± 1.7 days after cessation of treatment. None of the variables studied had a significant effect on the occurrence of estrus or the interval between treatment and the onset of heat.