Biomedical subjects

C Bailly

Publications and source records attributed to C Bailly.

At least 199 records · Page 11Linked to original sources

PubMed1995

Melanoma arising de novo in childhood: experience of the Gustave-Roussy Institute.

Between January 1956 and December 1990, 17 patients younger than 17 years with available pathological screens of de novo cutaneous melanoma, and with no other risk factors (xeroderma pigmentosum, giant congenital naevi, congenital melanoma or a proven family history of dysplastic naevus syndrome) were seen at the Gustave-Roussy Institute. The median age was 9 years and 9 months (range 2 years and 3 months-16 years and 9 months). The primary disease was located in the lower extremities in 10 cases, the trunk in five cases, and the upper extremities or head and neck in one case. The disease was localized for 10 patients at presentation (stage I), six had proven nodal metastasis (stage II) and one patient had nodal and breast metastases. The median thickness of the primary lesion was 2.89 mm (range 0.64-10). Five tumours were at level III on Clark's index, eight at level IV and four at level V. Six cases were classified as superficial spreading, two as unclassified radial growth, three nodular, three with Spitzoid cells, and three were unclassified. Two patients presented local recurrence with an initial unclassified melanoma, with a thickness greater than 2.5 mm. At a median follow-up time of 7 years, two patients had died from recurrent disease, and one patient had died from a second malignancy.

Adolescent↗

PubMed1995

Synthesis, DNA binding, and sequence specificity of DNA alkylation by some novel cyclic peptide-chlorambucil conjugates.

In an effort to investigate the potential of cyclic peptides as carriers for cytotoxic agents, we synthesized four cyclic peptide-chlorambucil conjugates: cyclo[Lys(CHB)-Lys(CHB)-Gaba-] (peptide Y), cyclo[Lys(CHB)-Gly-Lys(CHB)-Gaba-] (peptide A), cyclo[Lys(CHB)-beta-Ala-Lys(CHB)-Gaba-] (peptide B) and cyclo[Lys(CHB)-Gaba-Lys(CHB)-Gaba-] (peptide C). The cyclic peptides were synthesized by coupling protected amino acid residues in solution and the subsequent cyclization was performed by the pentafluorophenyl ester method as described previously (Sheh et al., 1990, 1993a,b). After deblocking the lysyl-carbobenzyloxy protecting group (Z), the conjugation was achieved by reaction with the pentafluorophenyl ester of chlorambucil (CHB). These cyclic peptides differ from one another in ring size and are disubstituted with CHB via the epsilon-amino group of the lysyl residue. The various conjugates were designed to study the effect of ring size on the mode of DNA binding and alkylation. A DNA-binding assay using lambda-DNA with ethidium bromide showed that whereas peptide Y and CHB have no observable binding affinity, the apparent binding constants for peptide A, peptide B and peptide C on lambda-DNA were determined to be 2.36 x 10(5), 1.27 x 10(5) and 3.50 x 10(5), respectively. Thus, it is suggested that cyclic peptides bearing aliphatic side chains attached to a ring larger in size than 14 members would be more favourable as regards augmenting the binding affinity. DNase I footprinting showed that no footprinting patterns were observed for the 253-mer fragment and 117-mer fragment with peptide A, but two new bands corresponding to G69 and G80 were observed for the 117-mer fragment. DNA alkylation studies using a piperidine cleavage assay on the 117-mer DNA fragment showed that the sequence selectivity, judged by reaction intensity observed with peptide A, peptide B and peptide C, was similar to that seen with CHB alone. The selectivity of alkylation for both CHB and its peptide derivatives appears to be: 3'-Pur-G-Pyr-5' > 3'-Pyr-G-Pyr-5' > 3'-Pyr-G-Pur-5' = 3'Pur-G-Pur-5'. However, there are apparent differences in the intensity of alkylation by peptides A, B, C and CHB at certain guanine residues.

Alkylation↗

PubMed1995

[Mucoepidermoid bronchial tumors. General review apropos of 2 new cases].

Muco epidermoïd tumors of the lung are rare tumors, derived from the minor salivary gland tissue of the proximal tracheo bronchial tree. We distinguish high grade and low grade malignity tumors. Authors are presenting two cases reports of mucoepidermoid tumors of the lung with a very aggressive behavior and a review of the literature. Attention is drawn to the difficult differential diagnosis with adenosquamous carcinoma of the lung.

Bronchial Neoplasms↗

PubMed1995

Design of composite drug molecules: mutual effects on binding to DNA of an intercalator, amsacrine, and a minor groove binder, netropsin.

A variety of spectroscopic and biochemical techniques have been employed to investigate the extent to which binding to DNA of an intercalator (amsacrine or its 4-carboxamide derivative SN16713) affects the binding of netropsin, a minor groove-targeted ligand, and vice versa. In general, rather little mutual interference has been found and the binding of one drug is compatible with binding of the other. The anilinoacridines exert little or no effect on the positioning of netropsin in the minor groove, judged by circular dichroism spectroscopy and electric linear dichroism, whereas netropsin has a perceptible effect on the intercalative binding of amsacrine, but not that of SN16713. Neither acridine drug prevents the netropsin-induced Z-->B structure reversion observed with poly(dG-dC).poly(dG-dC) in buffer containing 60% ethanol. The kinetics of dissociation of any one drug from its DNA complex are affected little, if at all, by the simultaneous presence of the other. Footprinting experiments with the several drugs singly or in combination reveal a certain amount of mutual interference, but the selective recognition of AT-rich sequences by netropsin tends to dominate the recognition pattern and is largely maintained in the presence of a considerable excess of amsacrine or its 4-carboxamide derivative.

Amsacrine↗

PubMed1995

Influence of the methyl substituents of a thiazole-containing lexitropsin on the mode of binding to DNA.

We have studied the DNA-binding properties of two thiazole-containing analogues of netropsin which differ by the absence (Thia-Nt) or presence (Methia-Nt) of methyl groups on the thiazole rings. The mode of binding to DNA of the two lexitropsins was investigated by circular dichroism, electric linear dichroism and viscosity measurements. The spectroscopic and hydrodynamic results indicate that the non-methylated lexitropsin binds to the minor groove of DNA, whereas the methylated analogue behaves as an intercalator. Our findings led to the notion that the methyl substituents on the thiazole rings might play a significant part in the intercalation process.

Animals↗

PubMed1995

Binding to DNA and cytotoxic evaluation of ascididemin, the major alkaloid from the Mediterranean ascidian Cystodytes dellechiajei.

The isolation of ascididemin from the Mediterranean ascidian Cystodytes dellechiajei is described. This alkaloid consists of a planar pentacyclic chromophore which was investigated for its DNA-binding and cytotoxic properties. Spectroscopic measurements provided evidence that the drug intercalates into DNA. DNase I footprinting assays indicated that the binding of ascididemin to GC-rich sequences is favoured over binding to AT-rich and mixed sequences. Chemical probes were used to detect ligand-induced structural changes in DNA. The alkaloid induces a hyper-reactivity of the DNA towards potassium permanganate, but not towards diethylpyrocarbonate, just as is the case with ethidium bromide; it has little effect on the catalytic activities of topoisomerases I and II. Ascididemin exhibits marked cytotoxicity towards human leukaemic cells in vitro and appears to be practically equally toxic for drug-sensitive and multidrug-resistant cell lines. The results suggest that DNA, but not topoisomerases, may represent the critical cellular target at which this marine alkaloid exhibits its potent cytotoxic properties in vitro.

Alkaloids↗

PubMed1995

[Granulomatous mastitis].

Six cases of granulomatous mastitis are reported. Based on a review of the relevant literature, the clinical features, etiology, and management of this pathologic entity are discussed. The definition of granulomatous mastitis is given and the characteristics that distinguish this condition from other inflammatory breast diseases are pointed out.

Adolescent↗

PubMed1994

Reaction of a biscationic distamycin-ellipticine hybrid ligand with DNA. Mode and sequence specificity of binding.

Molecular modeling of complexes between the octanucleotide d(CGATATCG)2 and either a monocationic or biscationic distamycin-ellipticine hybrid molecule predicted that the extra positive charge on the latter conjugate ligand should ensure tight fitting into the minor groove of the duplex without affecting intercalation of the ellipticine chromophore. To test this prediction, we have synthesized a biscationic compound Distel (2+) and investigated its interaction with DNA using various optical and gel electrophoresis techniques. Viscosity, fluorescence lifetime, and circular and linear dichroism measurements bear out the validity of the calculations and show that Distel (2+) does indeed come to lie with its distamycin moiety in the minor groove of DNA and its ellipticine ring intercalated nearby. Linear dichroism experiments with a range of polynucleotides indicate that, unlike its monocationic homologue, the biscationic ligand engages in bidentate binding to AT sequences but not to GC sequences. Footprinting studies employing DNase I and methidiumpropyl-EDTA.FeII as DNA cleaving agents reveal that the biscationic hybrid is notably selective for AT-rich sequences in DNA. The concentrations required to detect a clear footprint at AT sites with Distel (2+) are 4- to 10-fold lower than those required to produce comparable DNase I footprints with distamycin alone. Also, in accord with the energy-minimized model of the hybrid-oligonucleotide complex, chemical probing experiments using diethyl pyrocarbonate and osmium tetroxide reveal that the hybrid causes significant distortion of the DNA helix, explicable in terms of bending of the duplex toward the minor groove, which greatly enhances the reactivity toward probes in the major groove of the DNA. The experimental results help to identify the determinant factors, predominantly steric and electrostatic interactions, which shape the DNA-binding reaction. Thus, molecular modeling has correctly predicted the DNA-binding properties of a doubly charged ligand and shown that appending an auxiliary basic group onto the distamycin moiety was the right way to proceed in order to convert a nonspecific conjugate into a highly specific DNA reader.

Animals↗

PubMed1994

Daunomycin modifies the sequence-selective recognition of DNA by actinomycin.

The antitumour antibiotic actinomycin D normally binds to DNA by intercalation at sequences containing the CpG step, but in the presence of daunomycin it has been reported to interact with poly(dA-dT). This observation has neither been confirmed nor explained. Here we have used a photoreactive 7-azido derivative of actinomycin to study the effect of daunomycin on its binding to three DNA fragments. Daunomycin did indeed alter the binding of actinomycin to the DNA, such that the antibiotic was displaced from its primary GpC sites onto secondary sites in the DNA, though not to AT regions especially. These findings suggest a possible scientific explanation for the increased toxicity seen during combination chemotherapy with these two drugs.

Base Sequence↗

PubMed1994

The purine 2-amino group as a critical recognition element for binding of small molecules to DNA.

The expedient of preparing homologous DNA samples substituted with I for G, DAP for A, or both, has been used to investigate the role of the purine 2-amino group in determining the preferred binding sites for antibiotics on DNA. The selectivity of echinomycin for CpG steps, of actinomycin for GpC steps, and of netropsin for A + T-rich tracts, is seen to be radically altered in the substituted DNA molecules.

2-Aminopurine↗

PubMed1994

Stimulation of site-specific topoisomerase II-mediated DNA cleavage by an N-methylpyrrolecarboxamide-anilinoacridine conjugate: relation to DNA binding.

The DNA binding properties and effects on topoisomerase II of MePyGA, an anilinoacridine derivative bearing an N-methylpyrrolecarboxamide unit at position 1', have been compared with those of its precursor glycylanilinoacridine and the structurally related antileukaemic drug amsacrine. Electric linear dichroism spectroscopy reveals that MePyGA intercalates its acridine chromophore between DNA base pairs with a preference for GC-rich sequences, whereas both its structural analogue lacking the N-methylpyrrole unit and amsacrine intercalate into DNA without any strong sequence preference. The effects of the test drug on the catalytic activities of topoisomerase II were studied in vitro using purified calf thymus enzyme and 32P-labeled DNA. MePyGA stabilizes the topoisomerase II-DNA covalent complex and stimulates the cutting of DNA at a subset of preexisting topoisomerase II cleavage sites. The removal of the N-methylpyrrole unit abolishes both the GC-preferential binding to DNA and the topoisomerase II-mediated DNA cleavage. MePyGA and amsacrine stimulate the cleavage of DNA by topoisomerase II at different places: cleavage stimulated by amsacrine is consistent with the expected adenine requirement at position +1 whereas the predominant sites of DNA cleavage stimulated by MePyGA contain a cytosine at position +/- 1. This is the first instance where an anilinoacridine derivative differing only by the nature of the substituent at position 1' has been found to affect the catalytic activity of topoisomerase II differently. The spectroscopic and biochemical data lead to the conclusion that two functional domains can be identified in MePyGA: its anilino group can be regarded as a skeletal core to which are connected (i) the tricyclic acridine moiety which represents the DNA-binding domain and (ii) the N-methylpyrrole moiety which constitutes the topoisomerase II-targeted domain. The structure of the substituent at position 1' of the anilinoacridine chromophore evidently determines the location of the sites of DNA cleavage by topoisomerase II. These findings provide guidance for the synthesis and development of new topoisomerase II-targeted antitumor anilinoacridine derivatives.

Acridines↗

PubMed1994

Use of a photoactive derivative of actinomycin to investigate shuffling between binding sites on DNA.

A photoreactive analog of actinomycin (7-azidoactinomycin D) has been used in experiments to probe directly the shuffling hypothesis of Fox and Waring [Fox, K. R., & Waring, M. J. (1984) Nucleic Acids Res. 12, 9271-9285]. According to this theory, actinomycin D molecules initially interact with non-sequence-specific sites on DNA and subsequently "shuffle" along the polymer in a one-dimensional migratory fashion so as to locate their preferred sequence-dependent binding sites. In the study presented here, the drug-DNA complex was allowed to equilibrate (in the dark) for various periods of time, followed by photolysis which renders the complex irreversible and traps the ligand at its instantaneous binding sites. Visualization of the piperidine-labile sites and investigation of how the intensity of reaction at each site changes with time can provide direct confirmation of the shuffling hypothesis. The data reveal that actinomycin D does indeed engage in shuffling along the DNA. After only short equilibration times (20 s) actinomycin D is observed to bind to a variety of sites on the DNA, including many which are not regarded as canonical preferred binding sites at equilibrium. However, after longer periods of equilibration the intensity of reaction is shown to drop as a function of time at nonspecific sites, with corresponding increase at sequence-specific sites. In addition, base sequences which flank the intercalation sites can be seen to play a major role in influencing the binding and sequence specificity of actinomycin.

Base Sequence↗

PubMed1994

Interaction of human P1 and P2 protamines with DNA.

The interaction of two classes of human sperm protamines, P1 (HP1) and P2 (HP2, HP3, HP4), with DNA was investigated. Gel mobility shift assays with a range of DNA fragments of defined sizes show that, whatever its length, all the DNA is complexed with protamines at arginine to phosphate ratio of 0.1. Further addition of protamine molecules leads to a precipitation of the protamine-DNA complexes for arginine-phosphate ratio > or = 1.2. Fluorescence studies using the dye Hoescht 33258 as a fluorophore and DNAase I footprinting experiments suggest that P1 and P2 protamines bind at the DNA surface without apparent location in the minor or major groove of DNA. No differences in protamine-DNA interaction were observed between the two classes of human protamines P1 and P2. Moreover the binding to DNA was not influenced by the presence of zinc which induces the formation of a zinc-finger structure in protamine P2.

Binding, Competitive↗

PubMed1994

Localized chemical reactivity in DNA associated with the sequence-specific bisintercalation of echinomycin.

Four complementary footprinting and probing techniques utilizing DNAse I, methidiumpropyl EDTA (MPE).FeII, diethyl pyrocarbonate (DEPC) and KMnO4 as DNA-cleaving or DNA-modifying agents have been applied to investigate the sequence-specific binding to DNA of the antitumour antibiotic echinomycin. A 265 bp EcoRI-PvuII DNA restriction fragment excised from plasmid pBS was used as a substrate. Six regions of protection against DNAase I cleavage were located on the 265-mer: three sites encompass the sequences 5'-TCGA or 5'-GCGT and the three others contain 5'-GpG (CpC) dinucleotide sequences where the inhibition of DNAase I cutting by echinomycin is less pronounced. In contrast, MPE.FeII cleavage allows identification of only three echinomycin-binding sites on the 265-mer: two sites contain the sequence 5'-TCGA and one encompasses the sequence 5'-ACCA. Cleavage of DNA by MPE.FeII in the presence of echinomycin remains practically unaffected at the sequence 5'-GCGT, despite its identification by DNAase I as a strong site for binding the antibiotic, as well as at the two other sequences containing GpG steps. With both DNAase I and MPE.FeII, enhanced DNA cleavage is evident at AT-rich sequences in the presence of echinomycin. Enhanced reactivity towards KMnO4 and DEPC provides clear evidence for sequence-dependent conformational changes in DNA induced by the antibiotic. The experiments reveal that KMnO4 reacts most strongly with thymines located around, but not necessarily adjacent to, an echinomycin-binding site, whereas the carbethoxylation reactions caused by DEPC occur primarily at the adenine residues lying immediately 5' or 3' to the dinucleotide that denotes an echinomycin-binding site. The results reported here demonstrate that DEPC and KMnO4 serve as sensitive probes for different states of the DNA helix. It seems that the reaction with KMnO4 involves transient unstacking events, whereas the carbethoxylation reaction of DEPC requires larger-scale helix opening.

Base Sequence↗

PubMed1994

DNA recognition by intercalators and hybrid molecules.

Experiments are described which probe the role of the 2-amino group of guanine as a critical determinant of the recognition of nucleotide sequences in DNA by specific ligands. Homologous samples of tyrT DNA substituted with inosine or 2,6-diaminopurine residues in place of guanosine or adenine respectively yield characteristically modified footprinting patterns when challenged with sequence-selective antibiotics such as echinomycin, actinomycin or netropsin. The capacity of small molecules to recognise particular DNA sequences is exploited in the 'combilexin' strategy to target small molecules to defined sites in DNA. A composite molecule containing a distamycin moiety linked to an intercalating ellipticine derivative has been synthesised and shown to bind tightly to DNA but without much sequence-selectivity. Refinement of this molecule based on predictions from molecular modelling has led to the synthesis of a second generation derivative bearing an additional positive charge: this new hybrid molecule is strongly selective for binding to AT-rich tracts in DNA.

Antineoplastic Agents↗

PubMed1994

Interaction of two peptide-acridine conjugates containing the SPKK peptide motif with DNA and chromatin.

The interaction between DNA and two peptide-acridine conjugates containing one (1) or two (2) moieties of the Ser-Pro-Lys-Lys (SPKK) minor groove-binding peptide motif has been studied by a combination of hydrodynamic, biochemical and spectroscopic methods including diffusion-enhanced luminescence energy transfer (DELET) measurements with a Tb(III) lanthanide chelate as donor. Viscometric titrations do not reveal any significant difference between the two hybrid molecules which both unwind (by about 15 degrees) and extend the DNA similarly. DELET measurements show that the acridinyl chromophore of compounds 1 and 2 is much more accessible than that of a simple monointercalating drug such as acridine orange or ethidium. The accessibility factor increases proportionally with the peptide length, reflecting the extent of perturbation imposed upon the intercalating chromophore by the binding to DNA of the peptide moiety of the hybrids. Experiments with the osmium tetroxide-bispyridine reagent indicate that the two hybrid compounds both affect the local conformation of DNA rendering certain thymine residues conspicuously accessible to the probe. The drug-induced sites of hyperreactivity towards OsO4 in DNA are very similar with the exception of a short run of three T residues which is attacked more strongly in the presence of tetrapeptide-acridine conjugate 1 than with the octapeptide-acridine conjugate 2. These results are fully in agreement with previous footprinting studies and support the view that a minimum of two SPKK motifs is required to mimic the AT-specific minor groove binding antibiotic netropsin. On the basis of the DNA-binding properties of these two peptide-acridine hybrids, we present DNA-binding models in which the acridinyl moiety of compound 1 protrudes slightly outside the double helix but remains more or less parallel to the plane of the base-pairs. In contrast, with compound 2, where the octapeptide SPKKSPKK is bound to the minor groove, we postulate that the chromophore lies only partially overlapped with the base pairs in the intercalation site and, in addition, the heterocyclic chromophore is significantly tilted with respect to the double helix axis. Electric linear dichroism and DELET measurements with chromatin reveal that the presence of histone proteins affects the intercalative binding of compound 2 while it has practically no effect on the binding of compound 1.

Acridines↗

PubMed1994

Mode of DNA binding of bis-benzimidazoles and related structures studied by electric linear dichroism.

The binding mode of a series of bis-benzimidazole analogues of Hoechst 33258 to a variety of DNAs and polynucleotides has been investigated by electric linear dichroism. Two groups of compounds were examined: (i) benzoxazole and pyridoimidazole derivatives and (ii) pyridoimidazole analogs substituted with an N-alkoxyalkyl group either directed towards the minor groove or directed away from the minor groove. The ELD data indicate that the mode of binding of these drugs varies significantly with the sequence of the target DNA sequence. The DNA binding properties of these drugs are related to their topoisomerase inhibitory properties.

Base Sequence↗

PubMed1994

Comparative subcellular distribution of the copper complexes of bleomycin-A2 and deglycobleomycin-A2.

We have compared the cellular uptake and subcellular localization of 14C-labeled bleomycin-A2 (BLM) and deglycobleomycin-A2 in living KB3 cells. Both drugs exhibit poor internalization into cells but reveal significantly different intracellular distribution, with low and high accumulation into the cell nuclei for BLM and deglyco-BLM, respectively. The results indicate that the carbohydrate chain does not constitute a limiting factor for BLM permeation and is directly implicated in the intracellular distribution of the drug into cells.

Bleomycin↗