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Biomedical subjects

C Bailly

Publications and source records attributed to C Bailly.

At least 253 records · Page 14Linked to original sources
PubMed1990

Plasma membrane perturbations of KB3 cells induced by the bleomycin-iron complex.

The effect of the anticancer drug bleomycin on acyl chain order of KB cell membranes was examined by electron paramagnetic resonance and fluorescence polarization spectroscopies using respectively, the 5-doxyl stearic acid spin probe and the 1,6-diphenyl-1,3,5-hexatriene and the 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene fluorescent probes. Measurements of the order parameter, S, by the two techniques showed a perturbation of the plasma membrane fluidity with bleomycin-iron, while no effect was observed with bleomycin or iron alone. A kinetic study of the location of the 1,6-diphenyl-1,3,5-hexatriene fluorescent probe into the cell was followed by fluorescence microscopy. Lipid peroxidation measurements were also performed using isolated unsaturated lipids, intact cells, or isolated plasma membranes whose purity was checked by electronic microscopy. These membrane perturbation effects not observed with bleomycin-iron in the presence of a hydroxyl radical scavenger, dimethyl thiourea, or a chelating agent, desferrioxamine, were correlated with the ability of the complex to generate highly reactive oxygen species.

Bleomycin↗
PubMed1990

Modulation of HPV18 and BPV1 transcription in human keratinocytes by simian virus 40 large T antigen and adenovirus type 5 E1A antigen.

Transcription of early open reading frames initiated from the long control region (LCR) of HPV18 and BPV1 is known to be modulated by homologous and heterologous papillomarvirus E2 gene products. Using CAT constructs transfected into normal human keratinocytes, we show that SV40 large T antigen activates transcription from the LCR of both viruses, whereas Ad5-E1a antigen represses transcription from the HPV18-LCR but activates transcription from BPV1-LCR. Experiments using constructs containing subfragments of the HPV18-LCR cloned in enhancer configuration ahead of the SV40 early promoter or the HSV1-Tk promoter suggest that the effect of Ad5-E1a antigen on HPV18 transcription is probably due to a repression of the enhancer function of the LCR. The mechanism of transcription stimulation by SV40 large T antigen is less clear. The 230 bp Rsa1-Rsa1 central domain of the HPV18-LCR seems involved both in transcriptional stimulation by SV40 large T antigen and transcriptional inhibition by adenovirus E1a antigen.

Adenovirus Early Proteins↗
PubMed1990

Molecular recognition between oligopeptides and nucleic acids. DNA sequence specificity and binding properties of an acridine-linked netropsin hybrid ligand.

The binding to DNA of a mixed function ligand (NETGA) is described, in which a potential intercalating group, an acridine moiety, is incorporated at the carboxyl terminus of the minor groove binding oligopeptide netropsin skeleton. Scatchard analysis of absorption data provided evidence of two modes of binding to DNA with K1 = 9.1 x 10(5) M-1 at low r values (0.003-0.1), and a binding site size n = 10, indicative of binding of both moeities. At high binding ratios (greater than 0.1), K2 = 0.9 x 10(5) M-1 and n = 5 corresponding to external binding. Complementary strand MPE footprinting on a pBR322 restriction fragment showed NETGA binds to 5'-AAAT like netropsin. It causes enhanced cleavage by MPE, particularly at G-C rich sequences and remote from the preferred binding sites. Viscometry measurements provided evidence for biphasic modes of the two binding portions of NETGA. Fluorescence polarization and linear dichroism measurements were in accord with distinct modes of interaction of the acridine (intercalation) and oligopeptide (minor groove binding) portions of NETGA. LD measurements on NETGA indicate that the oligopeptide moiety (netropsin-like) has an orientation typical of minor groove binders, whereas the degree of intercalation of the acridine group is decreased by association of the oligopeptide moiety.

Aminoacridines↗
PubMed1990

Effects of parathyroid hormone and calcitonin on Na+, Cl-, K+, Mg2+ and Ca2+ transport in cortical and medullary thick ascending limbs of mouse kidney.

The effect of parathyroid hormone (PTH) on transepithelial Na+, Cl-, K+, Ca2+ and Mg2+ transport was investigated in isolated perfused cortical thick ascending limbs (cTAL) and that of human calcitonin (hCT) was tested in both cortical and medullary thick ascending limbs (mTAL) of the mouse nephron. The transepithelial ion net fluxes (Jx) were determined by electron probe analysis of the perfused and collected fluids. Simultaneously, the transepithelial voltage (PDte) and resistance (Rte) were recorded. In cTAL segments, PTH and hCT significantly stimulated the reabsorption of Na+, Cl-, Ca2+ and Mg2+, hCT generated a net K+ secretion towards the lumen and PTH tended to exert the same effect. Neither PDte nor Rte were significantly altered by either PTH or hCT. However, in the post-experimental period a significant decrease in PDte was noted. Time control experiments carried out under similar conditions revealed a significant decrease in PDte with time, which could have masked the hormonal response. In mTAL segments, Mg2+ and Ca2+ transport was close to zero, hCT did not exert any detectable effect on either PDte or Jcl-, JNa+, JK+, JMg2+ and JCa2+ in these segments. In conclusion, our data demonstrate that PTH and hCT stimulate NaCl reabsorption as well as Mg2+ and Ca2+ reabsorption in the cTAL segment of the mouse. These data are in agreement with and extend data obtained in vivo in the rat.

Animals↗
PubMed1990

Uptake and biological transformation of beta NiS and alpha Ni3S2 by human embryonic pulmonary epithelial cells (L132) in culture.

The cytotoxicity, biological transformation and interaction with plasma membranes of alpha Ni3S2 and beta NiS were studied on human embryonic pulmonary epithelial cells (L132 cell line) in culture. By establishing growth curves and survival curves, it was found that at equal molarity beta NiS has a higher inhibitory effect on cell growth than alpha Ni3S2 but a lower cytotoxic effect: the CL50 being 60 and 40 mumols/l respectively. As to their uptake, beta NiS crystals are preferentially phagocytized in their original form and then probably dissolved in the vacuoles, whereas alpha Ni3S2 is transformed in the extracellular space and in the phagocytic vacuoles into minute particles (10 nm) that are recovered bound to the cell membrane, phagocytic vacuoles and lysosomal membranes respectively. Energy dispersive spectrometry revealed that the particles bound to cell membranes no longer contain sulfur but only phosphorus and nickel as inorganic compounds. This observation suggests the formation of a Ni/P complex with the phosphate groups of membranous phospholipids and/or phosphotransferring proteins. The steady-state fluorescence polarization analysis, however, revealed a significant increase of membrane fluidity either induced by desaturation of aliphatic chains or directly by the cleavage of the fatty acid chains. These results clearly show a difference between beta NiS and alpha Ni3S2 concerning their cytotoxic effects, uptake, biological transformation and interaction with cell membranes.

Biotransformation↗
PubMed1990

Retinoic acid inhibits the production of collagenase by human epidermal keratinocytes.

Lattices made of collagen and fibroblasts can be used as dermal equivalents to grow human keratinocytes in vitro. When these cultures are performed in a medium containing delipidized serum, the lattice is eventually degraded by the growing epithelium. The digestion of the dermal equivalent is due to the secretion of a collagenase by the keratinocytes. This degradation does not occur in cultures containing total serum or supplemented with retinoic acid. We show in this paper that retinoic acid inhibits the secretion of this keratinocyte collagenase in a dose-dependent manner. In the light of this result, the possible involvement of collagenase inhibition in the therapeutic effect of retinoic acid in skin disorders and skin aging must be considered.

Blood Physiological Phenomena↗
PubMed1990

Isoproterenol increases Ca, Mg, and NaCl reabsorption in mouse thick ascending limb.

The effect of isoproterenol (Iso) on tubular transport in the thick ascending limb of Henle's loop (TAL) was investigated by in vitro microperfusion of MTAL (medullary) and CTAL (cortical) from White Swiss mouse kidney. The pattern of activation of adenylate cyclase along the distal tubule was investigated in this strain: results indicated that Iso stimulated adenylate cyclase fivefold in MTAL and ninefold in CTAL. Data from microperfusion experiments showed that Iso (10(-7) M in the bath) significantly and reversibly increased Ca and Mg reabsorption in CTAL. No net transport of Ca and Mg was observed in MTAL whether Iso was present or not. With regard to Na and Cl, Iso significantly stimulated their reabsorption in both segments and increased the transepithelial voltage in MTAL. Iso abolished K reabsorption in MTAL and induced a net K secretion in CTAL, the latter effect being also observed with 10(-9) M of Iso. When applied on CTAL, propranolol (10(-6) M in the bath) inhibited all these effects. These data indicate that beta-adrenergic agonists are involved in the multihormonal modulation of the TAL function.

Absorption↗
PubMed1990

Stability of conjugative and non-conjugative R-plasmids from Serratia marcescens to gyrase inhibitors.

The stability of conjugative and non-conjugative R-plasmids was compared using two gyrase inhibitors (novobiocin and ciprofloxacin). Conjugative R-plasmids from eighteen ticarcillin resistant Serratia marcescens were more stable than non-conjugative R-plasmids from eleven ticarcillin resistant bacteria of the same species. Moreover, novobiocin (gyrase B sub-unit inhibitor) is a better curing agent than ciprofloxacin (A sub-unit inhibitor).

Ciprofloxacin↗
PubMed1990

Evaluation of the sensitivity of microfilter paper assays in an anthropological study: results of samples from Cameroon and Tanzania.

Microfilter absorbed whole blood samples from 223 Tanzanian babies and 189 adults from Cameroon have been examined. Blood specimens are difficult to obtain from African suburban and rural areas, and lack of storage and transportation facilities can prevent the collection of samples. We evaluated some microassays employing whole blood collected on filter paper. This method is a well established technique in neonatal screening for endocrinometabolic diseases. We also developed microassays for whole dried blood spots to type AB0 blood groups and HIV disease using commercial reagents. Phenotype and gene frequencies for AB0 and hemoglobin systems as well as our results concerning the typings of thyroxine (T4), thyroid stimulating hormone (TSH), human immunodeficiency virus (HIV) and hepatitis B virus (HBV) are reported.

ABO Blood-Group System↗
PubMed1989

Subcellular distribution of a nitroxide spin-labeled netropsin in living KB cells. Electron paramagnetic resonance and sequence specificity studies.

A nitroxide spin-labeled netropsin was studied by EPR spectroscopy with respect to its uptake and localization in living KB cells. Whereas the drug was taken up readily, there was relatively little drug in the cytoplasm, but a significant concentration of the drug in the cell nucleus. The EPR signal in the latter site corresponded to a relatively freely rotating radical. The drug exhibited good intracellular stability up to 25 hr. While a delta Tm of 24 degrees between the spin-labeled netropsin and calf thymus DNA confirmed strong binding, the absence of any DNA elongation by viscometry was consistent with nonintercalative exterior binding which was confirmed to be minor groove specific by binding of the agent to T4 DNA with a delta Tm of 17.5 degrees. The sequence specificity of the DNA binding of the spin-labeled drug was confirmed by methidiumpropyl-EDTA (MPE) footprinting on a fragment of pBR322 DNA to be very similar to that of the parent netropsin, i.e. selective for AT-rich sites, with minor differences of protection afforded by introduction of the nitroxide label.

Base Sequence↗
PubMed1989

Design, synthesis, DNA binding, and biological activity of a series of DNA minor-groove-binding intercalating drugs.

A group of pseudopeptides, molecular combination of the natural antitumor agents distamycin or netropsin and the anilinoacridine chromophore (which is related to the synthetic antileukemic drug amsacrine) has been synthesized. Their DNA binding properties were determined and discussed in terms of their structural differences and in relation to their observed base-dependent binding. Binding data are consistent with a model in which the acridine nucleus occupies an intercalation site and the netropsin or distamycin residue resides in the DNA minor groove. Cytostatic and cytotoxic activities against a murine cell line are reported, as well as significant differences in the inhibition of DNA synthesis.

Animals↗
PubMed1989

Effects of glucagon on Na+, Cl-, K+, Mg2+ and Ca2+ transports in cortical and medullary thick ascending limbs of mouse kidney.

The effects of glucagon on transepithelial Na+, Cl-, K+, Ca2+ and Mg2+ net fluxes were investigated in isolated perfused cortical (cTAL) and medullary (mTAL) thick ascending limbs of Henle's loop of the mouse nephron. Transepithelial ion net fluxes (JNa+, JCl-, JK+, JCa2+, JMg2+) were determined by electron probe analysis of the collected tubular fluid. Simultaneously the transepithelial voltage (PDte) and the transepithelial resistance (Rte) were recorded. In cTAL-segments (n = 8), glucagon (1.2 x 10(-8) mol.1-1) stimulated significantly the reabsorption of Na+, Cl-, Ca2+ and Mg2+: JNa+ increased from 204 +/- 20 to 228 +/- 23 pmol.min-1.mm-1, JCl- from 203 +/- 18 to 234 +/- 21 pmol.min-1.mm-1, JCa2+ from 0.52 +/- 0.13 to 1.34 +/- 0.30 pmol.min-1.mm-1 and JMg2+ from 0.51 +/- 0.08 to 0.84 +/- 0.08 pmol.min-1.mm-1.JK+ remained unchanged: 3.2 +/- 1.3 versus 4.0 +/- 1.9 pmol.min-1.mm-1. Neither PDte (16.3 +/- 1.5 versus 15.9 +/- 1.4 mV) nor Rte (22.5 +/- 3.0 versus 20.3 +/- 2.6 omega cm2) were changed significantly by glucagon. However, in the post-experimental periods a significant decrease in PDte and increase in Rte were noted. In mTAL-segments (n = 9), Mg2+ and Ca2+ transports were close to zero and glucagon elicited no significant effect. The reabsorptions of Na+ and Cl-, however, were strongly stimulated: JNa+ increased from 153 +/- 17 to 226 +/- 30 pmol.min-1.mm-1 and JCl- from 151 +/- 23 to 243 +/- 30 pmol.min-1.mm-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Retinoic acid improves epidermal morphogenesis.

Hyper- and hypovitaminosis A both provoke epithelial pathologies in animals and humans. This suggests that a critical level of retinoic acid (RA) is required in vivo for the maintenance of normal architecture and function of these tissues. However, no beneficial, but only adverse effects of RA on epithelia have been so far observed in vitro. For instance, addition of RA to keratinocyte cultures has been shown to inhibit epidermal differentiation while this process is stimulated by serum delipidization, which reduces RA concentration in the medium. Assuming that the previous failure to demonstrate beneficial effects of RA on the epidermal phenotype in vitro was due to culture conditions too far from the in vivo conditions we decided to reevaluate the effect of RA in a culture system optimized for epidermal morphogenesis: the "emerged dermal equivalent." When human keratinocytes were grown in such a system with total fetal calf serum, the resulting epithelium was very similar to normal epidermis. But when delipidized serum was used, the epithelium was abnormal in the direction of excessive maturation (hyperkeratosis). When physiological concentrations of RA (10(-9) and 10(-8) M) were added to the delipidized serum supplement, a normal architecture (orthokeratosis) was restored. However, as classically described in the literature, higher RA concentrations (greater than 10(-7) M) reduced epidermal maturation and produced parakeratosis. Thus, although it is unquestionable that RA reduces the synthesis of epidermal-specific differentiation markers, an optimal epidermal morphogenesis seems to be achieved only in the presence of a critical RA concentration.

Cell Differentiation↗
PubMed1989

Clinical value of N-myc oncogene amplification in 52 patients with neuroblastoma included in recent therapeutic protocols.

Southern blot analysis of neuroblastoma (NB) cell DNA from 52 patients (58 samples) allowed the detection of an N-myc amplification on three of the 13 BM samples and three of 13 tumor samples at diagnosis, on two of 17 tumor samples taken after induction therapy, on three of seven BM samples and two of the five local tumor samples taken after relapse. N-myc was amplified in two of the 15 patients with stage I to III NB and in 10 of the 36 patients with stage IV neuroblastoma over 1 year of age. Conclusions from the analysis are as follows: first tumor samples obtained on previously treated patients are histologically modified and detection of N-myc amplification is not accurate; consequently N-myc amplification must be defined at diagnosis. Surgical biopsies of the primary tumors can, however, be delayed and malignant cells obtained by ultrasound-guided punctures or analyzed on bone marrow samples if they represent more than 50% of the total population. Second, any attempt to define the prognostic value must be performed on a group of patients treated with a new aggressive protocol of chemotherapy; it will require a multiparametric analysis including, in particular, results of an extensive clinical staging at diagnosis and histological criteria.

Child↗
PubMed1989

Immunological detection of neuroblastoma cells in bone marrow harvested for autologous transplantation.

In about 50% of patients with stage IV neuroblastoma, micrometastases are present in the bone marrow when it is harvested for an autograft to follow induction therapy, and the risk of graft contamination by neuroblastoma cells has been the rationale for the use of a purging procedure. However, bone marrow metastases are detected with trephine biopsies which only explore the sites biopsied and do not reflect potential contamination of the pooled marrow harvested for autograft. A two-colour fluorochrome labelling method is described which permits as few as 1 neuroblastoma cell in 100,000 normal bone marrow cells from the autograft to be detected. Three monoclonal antibodies (UJ13A, H11 and 11.14) which react with neuroblastoma cells are used as single reagent in combination with a fourth anti-panleucocyte antibody. This method requires only 2 h for the analysis of three million marrow cells from the autograft, and is more effective than alkaline phosphatase staining with the same monoclonal antibodies. Results were compared with conventional techniques (four biopsies and four aspirates) carried out at the same time in 34 consecutive patients. Of 18 cases with negative aspirates and biopsies, neuroblastoma cells were detected in two autografts by the immunological method. Of 16 cases with positive aspirates and/or biopsies, 10 autografts were positive by the immunological method and six were negative. Thus, marrow micrometastases were detected in 16 of the 34 patients, but the autograft contained malignant cells in only 12 of these patients and the immunological analysis demonstrated that the use of a purging procedure allowed the elimination of neuroblastoma cells from the autograft before its reinjection to the patients.

Antibodies, Monoclonal↗
PubMed1989

The human papillomavirus type 18 (HPV18) E2 gene product is a repressor of the HPV18 regulatory region in human keratinocytes.

The human papillomavirus type 18 (HPV18) long control region (LCR) harbors transcriptional promoter and enhancer elements. Recombinant plasmids bearing all or part of the HPV18 LCR cloned in enhancer or promoter configuration upstream of the chloramphenicol acetyltransferase (CAT) gene were transfected into human fibroblasts and keratinocytes. Although the HPV18 enhancer can function in the absence of E2 gene products in both fibroblasts and keratinocytes, the promoter activity of the HPV18 LCR is detectable in keratinocytes but not in fibroblasts, suggesting that it is tissue specific. This promoter activity was repressed in human keratinocytes not only by the bovine papillomavirus type 1 E2 gene product but also by the homologous HPV18 E2 gene product. The promoter involved in the HPV18 E2 repression is located within a 230-base-pair domain directly upstream of the E6 open reading frame of the HPV18 LCR and is probably the previously identified E6 promoter. Although one cannot rule out the possibility that this repressing effect is mediated by a truncated form of HPV18 E2 protein, as was previously demonstrated for bovine papillomavirus type 1, a more likely explanation would be that the full-length HPV18 E2 protein behaves as a repressor. Indeed, at the same doses at which it inhibits transcription from the homologous HPV18 LCR, the HPV18 E2 gene product activates transcription from constructs bearing E2-binding palindromes cloned in enhancer configuration upstream of a heterologous promoter. The fact that the homologous HPV18 E2 gene product acts as a transcriptional repressor of the HPV18 LCR suggests a possible explanation for the overexpression of E6 and E7 open reading frames in cervical carcinoma cells and in cell lines derived from them.

Base Sequence↗