Comparison of different staining procedures for the flow cytometric analysis of U-937 cells infected with different Leishmania-species.

The human macrophage cell line U-937 infected with different Leishmania species, Leishmania mexicana amazonensis (Lma), Leishmania donovani (Ld) and Leishmania infantum (Li), was analyzed by flow cytometry (FCM). Leishmania spp. were labeled with different stains prior to the infection of the U-937 cells (BCECF-Am, PKH2-GL and SYTO 17) or after the infection (AO, FITC-conjugated monoclonal antibodies, PI). Infected cells were analyzed by flow cytometry, fluorescence microscopy and in parallel microscopically after Giemsa staining. The data obtained by these two methods were compared to decide which method is mostly appropriate for detection and estimation of the infection rate. Three fluorescent stains were suitable: BCECF-Am, SYTO 17 and FITC-conjugated MoAb with 0.02% digitonin. None of the vital stains gave evaluable results after 3 days of incubation.

[Antiprotozoal effects of benzodiazepine derivatives]. / Antiprotozoäre Wirkungen von Benzodiazepinderivaten.

It is known that some derivatives of the benzodiazepine group act not only as antipsychotic drugs but also have inhibitory effects on the growth of protozoa. The influence of imipramine and its derivatives clomipramine and desipramine on the multiplication of Crithidia luciliae, Leishmania mexicana amazonensis, Trypanosoma cruzi and Trichomonas vaginalis was investigated using in vitro cultivation of the parasites and compared with the effects of chlorpromazine and metronidazole. All trypanosomatides used were inhibited by imipramine and its derivatives with clomipramine having the strongest influence on the growth of parasites (ID50 12.5-35 micrograms/ml). The Trichomonas vaginalis strain used was susceptible to metronidazole but it was nearly resistant to the tricyclic compounds tested (ID50 greater than 100 micrograms/ml).

Antiviral activity of Norakin (triperiden) and related anticholinergic antiparkinsonism drugs.

In view of the coincidence of antiviral and antiparkinsonism activities of amantadine four antiparkinsonism drugs, NorakinR (triperiden), ParkopanR (trihexyphenidyl), AntiparkinR (diethylbenzhydramine) and AkinetonR (biperiden) were tested for antiviral activity in various virus-cell systems. Norakin inhibited the replication of influenza A viruses in chick embryo fibroblast, MDCK and Ehrlich ascites tumour cells. It also inhibited the replication of measles virus in Vero cells, 50% inhibitory concentrations being 2-6 micrograms/ml. The drugs were also active against influenza B virus. Several representatives of other virus families, e.g. vaccinia, vesicular stomatitis, polio type 1 and herpes simplex type 1 viruses were insensitive to the compounds.

Occurrence of amantadine- and rimantadine-resistant influenza A virus strains during the 1980 epidemic.

The sensitivities to amantadine and rimantadine of influenza A virus epidemic strains were assayed by the haem-adsorption reduction test in mouse Ehrlich ascites cells in comparison with prototype strains and a rimantadine-resistant mutant. Besides a majority of sensitive strains, two relatively resistant epidemic strains were identified. The possible origin of resistant strains and their importance for medical practice are discussed.

Effects of 3'-fluorothymidine, nalidixic acid, and mitomycin C on temperature-sensitive mutants of the DNA polymerase of phage T4.

The temperature-sensitive DNA polymerase mutator mutants A58 and L98 are less inhibited by 3'-Fluorothymidine than the T4 wild type and the antimutator mutant CB121, in consequence of the assumed differences between the polymerase-associated exonuclease activities. This interpretation is confirmed by results with nalidixic acid and mitomycin C. The use of systems of different temperature-sensitive mutants of one or more genes is proposed for 1.) investigating the mode of action of drugs, 2.) studies on the mechanism of enzyme action and the functions affected in temperature-sensitive enzymes, and 3.) for enzyme-specific drug screening.