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Biomedical subjects

J Barbe

Publications and source records attributed to J Barbe.

At least 37 records · Page 2Linked to original sources
PubMed1993

Synthesis and antiparasitic activity of new 1-nitro, 1-amino and 1-acetamido 9-acridinones.

The synthesis of 1-amino-10-alkyl-9-acridinones 4 and 5 and of homologous 9-thio-acridinones 7 and 8 are described. Similarly, the synthesis of 1-nitro-4-(2'-aminoethylamino)-9-acridinones 13 and 15, is described. Compound 4 was used as starting material for the preparation of 10-alkyl-9-acridinone dimers 6, bridged with an alpha,omega-diamido chain. Compound 15 was selected for biological investigations on pathogenic parasite strains, and a promising antiamoebic activity could be shown.

Acanthamoeba↗
PubMed1992

Induction of ribonucleoside diphosphate reductase gene transcription by chemicals in Escherichia coli.

A fusion between the promoter of the nrdA gene of Escherichia coli and the lacZ gene has been constructed, and the induction of nrdA gene expression by 20 organic and 20 inorganic chemicals has been studied. The inducing compounds of the SOS genes, such as bleomycin, captan, ciprofloxacin, enoxacin, hydroxyurea, N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C, nalidixic acid, ofloxacin and hexavalent chromium compounds also trigger the expression of the nrdA gene. Other chemicals such as aluminium, manganese and zinc salts, reported as negative in the SOS Chromotest, are also inducers of the nrdA gene. These results suggest that ribonucleoside diphosphate reductase transcription is increased by chemicals able to either block DNA synthesis or to alter the enzymes participating in the DNA replication. Induction of nrdA gene is an effect to be further considered in the study of alterations produced by physical or chemical treatments which act upon DNA metabolism.

Escherichia coli↗
PubMed1991

Chromogenic method for rapid isolation of recA-like mutants of gram-negative bacteria.

We have devised a rapid and widely applicable color test for detecting recA-like mutants of gram-negative bacteria. The technique depends on decreased expression of an Escherichia coli recA-lacZ fusion in recA mutants and uses a broad-host-range plasmid to transfer the fusion gene into new species. We describe the isolation of a recA-like mutant of Pseudomonas syringae by this technique.

Escherichia coli↗
PubMed1990

Synthesis of two novel thioacridinic derivatives and comparison of their in vitro biological activities.

Two novel compounds, 3-amino-9-(diethylaminoethylthio) acridine and 9-diethylaminoethylthioacridine, were synthesized and characterized. They were shown to be cytotoxic against K562 and Raji cell lines. A concentration of 10(-5) M killed around 40% of the cells after 3 h time of incubation. Intercalation into DNA was more efficient when a protonated nitrogen was present in a side chain of the ring system. At the cytotoxic concentrations (10(-5) M, 10(-6) M), inhibition of nucleic acid synthesis in K562, Raji cell lines and human leukocytes has been shown. The results presented suggest that the cytotoxicity and the inhibition of nucleic acid synthesis of the two compounds studied are inversely related to their intercalating capability into the DNA helix.

Acridines↗
PubMed1989

Isolation of a high frequency donor of Rhodobacter capsulatus by integration of the plasmid pMT1000 into the chromosome.

The temperature-independent clone of Rhodobacter capsulatus UA7041, carrying the temperature-sensitive plasmid pMT1000, has been obtained by selection for plasmid markers at the non-permissive temperature. The transfer to Escherichia coli of all drug resistance encoded by pMT1000 was of about 10(-7) when the donor was the UA7041 strain, and of 5 x 10(-4) when the donor was the temperature-sensitive strain of R. capsulatus. Electrophoretic analyses showed no plasmid band typical of the autonomous pMT1000 in the UA7041 strain. Furthermore, UA7041 cells were also able to mobilize chromosomal markers of R. capsulatus at a frequency of about 10(-4) per donor cell. All these results lead us to conclude that the plasmid pMT1000 is integrated in the chromosome of the UA7041 strain. The analysis of the co-transfer frequencies of trp and his markers has shown that the chromosome mobilization in the UA7041 strain of R. capsulatus is unidirectional from a single origin. Our data also show that the pMT1000 plasmid may be useful to the construction of chromosomal, high-frequency donor strains.

Bacteria↗
PubMed1983

Discriminated induction of SOS functions in Escherichia coli by alkylating agents.

Treatment of Escherichia coli with the alkylating agents diethyl sulphate, ethyl methane-sulphonate and N-methyl-N'-nitrosoguanidine produces a different pattern of expression of SOS functions. There is a full induction of recA-dependent inhibition of cell respiration, a slight induction of lambda prophage, and no inhibition of cellular division. In a comparative study with bleomycin, an agent which is able to induce these three SOS functions, we have also shown that the differences in expression of SOS functions are not due to any variation in the pattern of DNA synthesis, or DNA degradation after treatment with alkylating agents. These results suggest that the kind of damage induced in the DNA may be important in determining which SOS function is expressed.

Alkylating Agents↗
PubMed1980

An improved method for routine analysis of polyamines in biological fluids with a conventional amino acid analyzer.

An accurate and precise mechanized ion-exchange chromatographic method for the estimation of polyamines in biological fluids is described. The method includes the recent improvements developed for ion-exchange analysis of polyamines: the use of sulfonated polystyrene cation-exchange resin with a bead diameter of less than 10 micrometers and a continuous fluorescent detection with o-phthalaldehyde. Four different procedures for the removal of protein before analysis of polyamines in plasma have been compared. Linearity of the fluorescence detection, reproducibility (intra, inter assay) and precision of the retention times are reported. Furthermore, the method is characterised by the simplicity of the sample preparation, a clear and rapid elution programme and especially by its routine applicability, as shown during the last six months in the Centre Antoine-Lacassagne.

Amino Acids↗
PubMed1980

[High resolution proton magnetic resonance study of a series of 9-substituted acridines: correlation with biological activities].

250 MHz 1H N.M.R. spectra of a set of 9-substituted derivatives of acridine as solutes in DMSO-d6 were studied. Because of ABCD coupling figures, magnetic parameters were determined by means of simulated spectra. Semi-empirical correlations were proposed for chemical shifts. Moreover, pi distribution in the heterocycle was investigated. Results are discussed in relation to some weak biological properties of the acridine drugs.

Acridines↗