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SDZ NIM 811 is a cyclosporin A analog that is completely devoid of immunosuppressive capacity but exhibits potent and selective anti-human immunodeficiency virus type 1 (HIV-1) activity. The mechanism of action of SDZ NIM 811 is clearly different from those of all other anti-HIV agents described so far. In cell-free assays, it is not an inhibitor of reverse transcriptase, protease, integrase, and it does not interfere with Rev or Tat function. SDZ NIM 811 does not down-regulate CD4 or inhibit fusion between infected and uninfected, CD4-expressing cells. p24 production from chronically HIV-infected cells is not impaired either. To elucidate the mode of action of SDZ NIM 811, we performed DNA PCR analysis in HIV-1 IIIB-infected MT4 cells in one cycle of virus replication. The effects of SDZ NIM 811 on the kinetics of viral DNA synthesis, appearance of two-long terminal repeat circles (2-LTR circles), and integration of DNA were studied. SDZ NIM 811 inhibited 2-LTR circle formation in a concentration-dependent manner, which is indicative of nuclear localization of preintegration complexes. Half-maximal inhibition was achieved at 0.17 microgram/ml; this concentration is close to the 50% inhibitory concentrations (0.01 to 0.2 microgram/ml) for viral growth inhibition. As expected, integration of proviral DNA into cellular DNA was also inhibited by SDZ NIM 811. Analysis of the viral particles produced by SDZ NIM 811-treated, chronically infected cells revealed amounts of capsid proteins, reverse transcriptase activity, and viral RNA comparable to those of the untreated control. However, these particles showed a dose-dependent reduction in infectivity (50% inhibitory concentration of 0.028 microgram/ml) which indicates that the assembly process is also impaired by SDZ NIM 811. Gag proteins are postulated to play a role not only in assembly but also in early steps of viral replication, e.g., nuclear localization of the preintegration complex. Recently, it was reported that HIV-1 Gag protein binds to cyclophilin A, the intracellular receptor for cyclosporin A. Interference with Gag-cyclophilin interaction may be the molecular basis for the antiviral activity of cyclosporin A and its analogs.

A new encapsulation method was developed for the cultivation of mammalian cells. The capsules were produced using a solution of sodium cellulose sulphate (CS)(1.5%) and poly-dimethyl-diallyl-ammoniumchloride (PDMDAAC). When CS droplets fell into the precipitation bath consisting of a 2% solution of PDMDAAC, immediately a membrane at the interphase was built up. The influences of varying encapsulation process parameters on capsule characteristics, cell growth, and monoclonal antibody production were tested. This new method showed advantages when compared to other methods mainly due to time simplicity of the whole process.

Summary: 1. On the basis of new theoretical considerations developed by us a new and reliable method has been elaborated for the rapid determination of water deficit in plant cultures. 2. In paper-chromatograms of plants optimally supplied with water free proline is shown to be present in very small amounts, usually only as traces. Comparative experiments showed that in cases of water shortage the proline content of the leaves of the plant strikingly increases. This commonly occurs in every phase of development of mono- and dicotyledons. 3. Drought-resistant plants synthetize more proline than varieties less resistant to water deficit when equally water deficient.4. By a method which does not require chromatography the procedure of tests has been accelerated so that leaf extract containing amino acid mixture was dropped onto a chromatogram paper and immediately treated with isatine. In this test the effect of slight, permanent or medium water deficit upon proline content is so great that extracts react with isatine to give an intense dark blue colour which suppresses the reddish-brown colour of other amino acids. 5. To avoid the necessity of preparing isatine reagent frequently, because it loses its amino acid sensitivity very rapidly, a new isatine solution has been formulated. Our isatine-paper indicator prepared with this solution keeps its reactivity with amino acids 5 to 6 months. 6. An unusually high proline concentration occurs also if the salt content of irrigation water or also of the soil is high. The increase of the proline level indicates therefore physiological dryness.

A NUMBER of compounds are known to be translocated in the transpiration stream. These include the building blocks needed for protein synthesis and also compounds postulated to play a part in the regulation of protein synthesis in leaves1,2. In the present investigation the spectrum of amino-acids translocated in the bleeding sap of three plant species was compared to provide data on the species specificity of the pattern observed.