Extracellular ATP and adenosine modulate tumor necrosis factor-induced lysis of L929 cells in the presence of actinomycin D

Extracellular ATP in concentrations of 0.5 to 2.5 mM modulates TNF-induced cytolysis of L929 cells in the presence of actinomycin D. When present throughout the entire assay period, it inhibits the TNF-induced cytolysis. ADP was less active whereas AMP and GTP were nonreactive. However, inhibition was also achieved by adenosine that was nearly as active as ATP. Yet, the inhibitory effect of ATP was not due to hydrolysis by ectoenzymes to form adenosine. Thus, the nonhydrolyzable ATP analogue adenyl(beta-gamma-methylendiphosphate) was equally effective in inhibiting TNF-induced cytolysis. Moreover, no conversion of ATP into adenosine was observed during the entire assay period. However, inhibition no longer occurred when the TNF and ATP containing medium was removed after 5 h and replaced by a fresh medium containing TNF and no ATP. We now observed substantial enhancement of the TNF-induced cytolysis by ATP. Finally, treatment with N6-(R-phenylisopropyl)adenosine or with aminophylline, which are thought to downregulate adenosine receptors and to prevent binding of ligands to adenosine receptors, respectively, abolishes adenosine and ATP-mediated inhibition. Again, substantial enhancement of the TNF-induced cytolysis was observed by ATP and only a minor effect by adenosine. The results together suggest that ATP interacts with purinoceptors on the plasma membrane and is capable to enhance and inhibit TNF-induced cytolysis under appropriate conditions. The outcome of the ATP-induced modulation may be influenced by adenosine receptors.     

Raman spectroscopic investigation of the interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes.

The interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes is investigated by Laser-Raman spectroscopy. As revealed by the methylene C-H stretching mode the phase transition of the hydrocarbon chains near 40 degree C is eliminated in the presence of gramicidin A. Liposomes prepared from a mixture of lecithin and cholesterol seem to be unaffected by gramicidin A and show only the normal broadened phase transition.     

Copy number and distribution of P and I mobile elements in Drosophila melanogaster populations

The distribution of the number of copies of P and I transposable elements per genome was investigated by in situ hybridization for a large set of Drosophila melanogaster strains. These included the P, Q and M types of the P-M system of hybrid dysgenesis. P element copy number varied widely (range 5–59). P and Q strains had around 40 copies whereas M strains generally had lower numbers (between 5 and 35) with one extreme value (52). The copy number of I elements appeared to be precisely regulated, as no strains were found outside the 15±5 range. The number of copies of the two families were independent. An excess of P copies on the X chromosome compared with the autosomes was found for the P and Q strains, but not for M strains. Among X-inserted P sites, a very high frequency of occupation was found at the tip of the X chromosome (cytological site 1A), especially for P and Q strains. The possible regulatory role in the P-M system of X-inserted P sites is discussed.     

Mutations for the autosomal recessive and autosomal dominant forms of polycystic kidney disease are not allelic

Summary The autosomal dominant form of polycystic kidney disease (ADPKD) has been linked to the -globin gene locus on 16p. Linkage studies between the autosomal recessive type (ARPKD) and the 3 HVR of the -globin gene cluster showed that the ARPKD and ADPKD are not allelic.     

Serum-free growth medium for the cultivation of a wide spectrum of mammalian cells in stirred bioreactors

A serum free medium was developed, that could be used for the large scale propagation of various cell lines in bioreactors. The medium is based on a 1:1 mixture of Iscove's Modified Dulbecco's Medium and Ham's Medium F12, supplemented with transferrin, insulin and a BSA/oleic acid complex. Several myelomas, hybridomas derived from different myelomas and spleen cells, and other lymphoid and non-lymphoid cell lines were cultivated at growth rates comparable to those observed using serum-supplemented media. There was furthermore no reduction in the formation of products such as monoclonal antibodies or recombinant human interleukin-2.Abbreviations Ag8 Mouse myeloma cell line P3-X63-Ag8.653 - BME Basal Medium Eagle - BSA Bovine Serum Albumin - DMEM Dulbecco's Modified Eagle's Medium - EDTA Ethylenediaminete-traacetic Acid - e-PC Phosphatidyl choline from egg yolk - FCS Fetal Calf Serum - FGF Fibroblast Growth Factor - GHL Glycyl-histidyl-lysine - HDL High Density Lipoprotein - HPL Human Plasma Lipid - IF 1:1 mixture of IMDM and Ham's F12 - IMDM Iscove's Modified Dulbecco's medium - LDL Low Density Lipoprotein - NS1 Mouse myeloma cell line NSI-1-Ag4-1 - PBS Phosphate Buffered Saline - s-PC Phosphatidylcholine from soy beans - s-PE Phosphatidylethanolamine from soy beans - s-lecithin lecithin from soy beans     

Multipoint linkage analysis of the short arm of chromosome 11 in non-insulin dependent diabetes including maturity onset diabetes of youth

Summary Members of three families with maturity onset diabetes of youth (MODY) and seven with common type 2 diabetes were typed for six DNA markers (H-RAS, INS, HBBC, PTH, CALC1, CAT) on the short arm of chromosome 11. Using conventional pairwise linkage analysis, close linkage in the MODY families was excluded for all six markers. By multipoint analysis and a genetic map of the short arm of chromosome 11, MODY was excluded from a region of at least 35 and up to 60 centiMorgans (cM) on the short arm of chromosome 11. Multipoint analysis in the type 2 families also excludes linkage to the INS, H-RAS region of at least 3 and up to 30 cM. This study using multipoint linkage analysis in non-insulin dependent diabetes provides strong evidence against a role for mutations in or around the insulin gene in the causation of MODY or type 2 diabetes in the families studied.