Search PubMed⌕ Search

Biomedical subjects

M Chambon

Publications and source records attributed to M Chambon.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cathepsin D cytosolic assay and immunohistochemical quantification in human prostate tumors.

We quantified cathepsin D by immunoradiometric assay (IRMA) and quantitative immunohistochemistry in fifteen human prostate cancers, seventeen BPH, and nine normal prostates. The cytosolic cathepsin D concentration was higher in prostatic carcinoma (mean: 31.5 pmol/mg cytosol proteins; range: 10.2-66.2) than in normal prostate (16.0 pmol/mg cytosol proteins; 7.2-25.5; P = 0.01). Prostatic hyperplasia showed intermediate values (20.2 pmol/mg cytosol proteins; 7.6-33.9). Immunostaining of cathepsin D and prostatic acid phosphatase on serial frozen sections of prostate tissues was only observed in glandular epithelial cells. Immunostaining was quantified by computer-assisted image analysis as an quantitative immuno-cytochemical score (QIC score) expressed in arbitrary units (A.U.). QIC scores for cathepsin D were dispersed and had a tendency to be higher in benign prostatic hyperplasia (mean: 178.3 A.U.; range: 95-297) compared to normal prostate (85.2 A.U.; 2-173 P < 0.01) and prostatic carcinoma (90.0 A.U.; 21-179 P = 0.0002). Prostatic cathepsin D levels in cytosols or immunostaining sections were independent of other clinicobiological parameters.

Acid Phosphatase↗
PubMed1994

Replication of echo virus type 25 JV-4 reference strain and wild type strains in MRC5 cells compared with that of poliovirus type 1.

In echo virus type 25/JV-4 the shut off of host cell protein synthesis took significantly longer and the kinetics of the synthesis of viral proteins and viral RNA occurred much later than in the poliovirus. However, these characteristics impaired neither polyprotein processing nor virus production in the JV-4 strain. In contrast the two wild strains M.1262 and Th.222 had a lower virus yield than strain JV-4. The presence of a high Mr protein in the pattern of viral proteins of wild strains suggested that a defect in the polyprotein processing was responsible for the decreased virus yield. The infectious cycle of strain Th.222 differed from that of strains JV-4 and M.1262 in the rapid inhibition of host cell translation and the extent of viral protein synthesis. The sensitivity to actinomycin D was also investigated. Strain M.1262 was found to be insensitive. The virus yield of strains JV-4 and Th.222 was three- and fourfold lower respectively in the presence of actinomycin D. This sensitivity to the antibiotic was observed during viral RNA synthesis in strain JV-4 and during viral protein synthesis in strain Th.222. These results suggest that cellular factors are involved in the replication of echo virus type 25 strains in MRC5 cells.

Cell Line↗
PubMed1994

Mineral balance and whole body bone mineral content in very low-birth-weight infants.

Fat and mineral metabolic balance studies were performed in 25 normal very low-birth-weight infants (< or = 1500 g at birth) fed either pooled pasteurized human milk supplemented with calcium, phosphorus and magnesium, or a preterm formula. Calcium, phosphorus and magnesium intake were similar in both groups and averaged 100 mg/kg/day, 72 mg/kg/day and 8 mg/kg/day, respectively. Calcium and phosphorus retention was higher in the subjects fed fortified human milk than in those receiving a preterm formula (65 +/- 14 and 62 +/- 9 mg/kg/day versus 55 +/- 12 and 47 +/- 7 mg/kg/day respectively). The difference was only significant for phosphorus. Magnesium retention was similar in the two groups and averaged 3 mg/kg/day. Fat intake and absorption was significantly higher in the preterm formula fed group than in the one fed fortified human milk (5.5 +/- 0.4 g/kg/day and 88 +/- 4% versus 4.2 +/- 1 g/kg/day, 79 +/- 6% respectively). Assessment of the whole body bone mineral content by dual energy X-ray absorptiometry was performed at 3 and 6 months of age in another group of 25 low-birth-weight infants fed either fortified human milk or a preterm formula. Whole body bone mineral content (BMCt) was low (43.3 +/- 30.8 g of hydroxyapatite) at 3 months of age (theoretical term) compared to normal full-term newborns at birth. There was no significant influence of the diet. At 6 months of age, BMCt reached 168.6 +/- 36.6 g, a value similar to that of full-term newborns, with no significant difference between the two regimen groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Density↗
PubMed1994

Comparative sensitivity of the echovirus type 25 JV-4 prototype strain and two recent isolates to glutaraldehyde at low concentrations.

The sensitivity of two recently isolated antigenic variants of echovirus type 25 (Montpellier 76-1262 and Thionville 86-222) to glutaraldehyde (GTA) at low concentrations was compared with that of the JV-4 prototype strain. The purified viruses were treated under the same conditions with GTA at concentrations ranging from 0.002 to 0.10%. The wild strains exhibited significantly lower sensitivity to GTA than did the prototype strain; with 0.10% GTA, a 2 log10 unit reduction was obtained in 5 min for JV-4 and in 60 and 80 min for Montpellier 76-1262 and Thionville 86-222, respectively. A comparison with previous results obtained with poliovirus type 1 showed that the inactivation rates of echovirus type 25 wild strains were fivefold lower than those of the poliovirus type 1 Sabin strain. The comparative electrophoretic and immunoblot analyses showed differences in the results of GTA binding with capsid proteins of the viruses. Unlike in the poliovirus type 1 Mahoney strain and in the echovirus type 25 JV-4 reference strain, GTA produced only minor intermolecular cross-linkings in the viral particles of the two wild strains of echovirus type 25. Our results suggest that there are both intertypic and intratypic differences in the GTA sensitivities of enterovirus strains. They are of relevance to disinfection procedures in digestive endoscopy and to the choice of the enterovirus strain used for evaluating the efficacy of disinfectants.

Capsid↗
PubMed1992

Activity of glutaraldehyde at low concentrations against capsid proteins of poliovirus type 1 and echovirus type 25.

The activity of glutaraldehyde (GTA) against capsid proteins of poliovirus type 1 and echovirus type 25 was studied to understand the mode of action of this reagent against enteroviruses. The viruses were treated with GTA concentrations ranging from 0.005 to 0.10%. In the poliovirus particles, high-molecular-weight products were formed by 0.05% GTA, whereas in the echovirus particles, they were formed at 0.005% GTA. These products consist of complexes composed essentially of VP1 and VP3. There seemed to be differences in the composition of the complexes in the two viruses. Cross-linkings between the two polypeptides of the poliovirus capsid may be due to the accessibility to GTA of lysine residues on the loops of VP1 and VP3, which twist out from the surface of the shell.

Adsorption↗
PubMed1991

Nosocomial rotavirus infections in adult renal transplant recipients.

We conducted a 24-month survey of hospital-acquired rotavirus infections in 20 renal transplant recipients who received their graft during 1988. Four cases of nosocomial rotavirus infection were diagnosed (20% of patients), 3-34 days after graft. Two patients presented with severe diarrhoea and two with fever alone. The cases occurred mainly during the winter months and remained sporadic. None of our patients was found to have chronic excretion of rotaviruses. Contacts from paediatric cases can be ruled out. We concluded that rotavirus nosocomial infections were frequent in adult renal transplant recipients and suggest that screening for rotavirus is regularly performed in these immunodeficient patients who are very susceptible to hypovolaemia.

Adult↗
PubMed1991

Activity of glutaraldehyde at low concentrations (less than 2%) against poliovirus and its relevance to gastrointestinal endoscope disinfection procedures.

The activity of glutaraldehyde (GTA) at low concentrations (less than 2%) against poliovirus was assessed by a suspension procedure. The inactivation kinetics showed that concentrations of less than or equal to 0.10% were effective against purified poliovirus at pH 7.2; a 1 log10 reduction was obtained in 70 min with 0.02% GTA, and a 3 log10 reduction was obtained in 30 min with 0.10% GTA. GTA activity at low concentrations was greatly enhanced at alkaline pH, but was completely abolished at acid pH. In contrast, the inactivation assays on poliovirus RNA showed that it was highly resistant to GTA at concentrations up to 1.0% at pH 7.2. At pH 8.3 a low inactivation was noticed with 1.0% GTA. Our results are of relevance to hospital practice in digestive endoscopy investigations because there has been an increasing tendency to use low concentrations of GTA and very short contact times in disinfection procedures.

Disinfection↗
PubMed1991

Heterogeneity of capsid proteins of echovirus type 25 wild-type strain and prototype strain, studied by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting were used to compare the capsid proteins of 19 antigenic variants of echovirus type 25 wild-type strains isolated in France between 1976 and 1987 with those of the prototype JV-4 reference strain isolated in 1957. Immunoblots were developed by using polyclonal sera from rabbits and mice immunized with the reference strain. Immunoblotting patterns revealed reactivity only against viral protein VP1 for sera from both animals. Comparative immunoblotting patterns showed differences in the electrophoretic mobilities of viral protein VP1, especially for the Montpellier 76.1262 wild-type strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of [35S]methioinine-labeled viral polypeptides revealed that the two variant strains, Montpellier 76.1262 and Thionville 86.222, exhibited significant and reproducible shifts in the relative mobilities of VP1 and VP3 and, to a lesser extent, in those of VP0 and VP2. The relative mobility of VP4 seemed very similar for the JV-4 reference strain and the two variants. Interestingly, the structural differences in VP1 and VP3 of Montpellier 76.1262 were not correlated with the pattern of neutralization by monoclonal antibodies, unlike in our previous study, in which this strain differed from the prototype strain in only two epitopes. We concluded that, in addition to the heterogeneity of their biological and antigenic properties that we observed previously, echovirus type 25 wild-type strains may exhibit differences in their structural proteins.

Animals↗
PubMed1990

Impact on routine diagnosis of echovirus infections of intratypic differentiation and antigenic variation in echovirus type 25 studied by using monoclonal antibodies.

We studied the biological and antigenic properties of wild strains of echovirus type 25 isolated in France between 1982 and 1987 and compared them with the JV-4 prototype strains isolated in 1957. The wild strains differed from the prototype strain in their cellular tropism. The prototype strain grew readily in five cell lines (MRC5, MA 104, Vero, BGM, and HT 29-18), while for wild strains MRC5 and HT 29-18 cells were the most sensitive and supported growth to high titres (between 4.5 and 7.4 50% tissue culture infective doses per 0.05 ml). Plaques produced by wild strains were larger (6.05 +/- 0.94 mm in diameter [mean +/- standard deviation]) than those of the prototype strain (2.3 +/- 0.97 mm in diameter) and heterogeneous, even after cloning by three terminal dilution passages, which suggested heterogeneous virus populations. Virus neutralization with polyclonal monovalent sera showed that wild strains were significantly less neutralized by two reference immune sera than the prototype strain was. Monoclonal antibodies were raised against the echovirus type 25 JV-4 prototype strain. Nine clones with neutralizing activity were identified. Heterologous neutralizations of 14 clinical isolates revealed highly conserved, moderately conserved, and poorly conserved epitopes. The natural isolates differed from the prototype strain in two to four epitopes and can be classified into four different groups. We concluded that echovirus type 25, like coxsackie- and polioviruses, consists of heterogeneous viral populations with respect to biological and antigenic properties. In term of viral diagnosis, it may become increasingly difficult to identify recently isolated strains because of their antigenic variation.

Antibodies, Monoclonal↗
PubMed1990

Regulation of fatty acid synthetase by progesterone in normal and tumoral human mammary glands.

Progesterone and estrogens play an important role in the control of growth, differentiation and function of mammary epithelial cells. Their mechanism of action can be studied in human metastatic breast cancer cell lines (MCF7, T47D, ZR75-1...) that contain progesterone and estrogen receptors. We used this system to try to define progestin-regulated human genes which would permit to study progestin-regulation of gene expression in cell culture and to develop clinical markers of progestin-responsiveness. This paper summarizes our investigation of the progestin-regulated 250K protein, recently identified as human fatty acid synthetase (FAS).

Breast↗
PubMed1989

[A simple and rapid method to test the permeability of condoms to viruses].

phi x 174 and T7 coliphages can be used to find out if condoms are virus-proof. Protection against hepatitis B virus or papillomavirus contamination is not assured when T7, a 65 nm broad virus, leaks through the condom. The simple test can be used to establish a quality control norm for condoms.

Bacteriophage phi X 174↗
PubMed1989

Progestins and androgens stimulate lipid accumulation in T47D breast cancer cells via their own receptors.

Using electron microscopy, in the human breast cancer cell line T47D, the synthetic progestin R5020, and 5 alpha-dihydrotestosterone were shown to increase significantly the number of lipid droplets per cell section compared to control cells or estradiol- and dexamethasone-treated cells. Lipid accumulation, as measured by Oil Red O dying and by [2-14C]acetate incorporation, was observed at concentrations as low as 10 pM R5020 and 1 nM 5 alpha-dihydrotestosterone, and was always more abundant after progestin treatment. The progestin antagonist RU486 inhibited, in a dose-dependent manner, lipid accumulation initiated by the two hormones, whereas the androgen antagonist flutamide inhibited only the effect initiated by 5 alpha-dihydrotestosterone. Cytoplasmic lipid droplets accumulation was not observed in the BT20 breast cancer cell line, which contains neither progesterone nor androgen receptors. These results indicate that progestins and androgens increase lipid accumulation by interacting with their own receptor. Chromatographic analysis of [2-14C]acetate labeled lipids showed that R5020 and 5 alpha-dihydrotestosterone enhanced the accumulation of cellular triglycerides at least in part by increasing their synthesis and decreased the quantity of lipids released into the medium. To conclude, we have shown that progestins and androgens, via their own receptor, can induce the same triglyceride accumulation in T47D cells. This effect follows fatty acid synthetase induction and precedes cell growth inhibition, two responses also triggered by progestin and androgen in these cells.

Acetates↗
PubMed1989

[Gingival hyperpigmentation caused by dental restorations: the mechanism of detoxification using selenium].

X-ray microanalysis and electron diffraction made on granular metallic deposits of the gingival lamina propria, inducing partial periodontal tattoos, demonstrated that these deposits consisted of crystalline particles combining silver, sulphur and selenium. The role of selenium precipitating of silver and other metals as well as its role in detoxication are discussed.

Chemical Precipitation↗
PubMed1987

Fatty acid synthetase and its mRNA are induced by progestins in breast cancer cells.

The growth of hormone-dependent breast cancer cell lines (MCF7 and T47D) is inhibited in vitro by progestins which also induce several proteins. We have cloned cDNA sequences corresponding to one of them, a 250-kDa protein, and have shown that the corresponding mRNA is also rapidly induced by progestins (Chalbos D., Westley B., May F.E.B., Alibert C., and Rochefort H. (1986) Nucleic Acids Res. 14, 965-982). We show here that the 250-kDa protein is very similar, if not identical, to fatty acid synthetase: fatty acid synthetase is regulated to the same extent by progestins, the 250-kDa protein is specifically immunoprecipitated by antibodies to fatty acid synthetase, and fatty acid synthetase covalently labeled by [14C]pantothenate is immunoprecipitated by antibodies to the 250-kDa protein. The induction of fatty acid synthetase by progestin in cancer cells thus provides another model for studying the mechanism regulating steroid transcription in human cells. Since fatty acid synthetase regulation by progestins appears to be the opposite in cancer and normal mammary cells, this observation may also be a clue for understanding the role of progestins in mammary carcinogenesis.

Antibodies↗
PubMed1987

Estrogen-induced lysosomal proteases secreted by breast cancer cells: a role in carcinogenesis?

In an attempt to understand the mechanism by which estrogens stimulate cell proliferation and mammary carcinogenesis, metastatic human breast cancer cell lines (MCF7, ZR75-1) were found to secrete a 52,000 dalton (52K) protein under estrogen stimulation. Following its purification to homogeneity, the 52K protein was identified as a secreted procathepsin-D-like aspartyl protease bearing mannose-6-phosphate signals. This precursor displays an in vitro autocrine mitogenic activity on estrogen-deprived MCF7 cells and is able to degrade basement membrane and proteoglycans following its autoactivation. The total protease (52K + 48K and 34K) was detected and assayed by monoclonal antibodies and was found to be highly concentrated in proliferative and cystic mastopathies. In breast cancer, its cytosolic concentration appears to be correlated more to tumor invasiveness than to hormone responsiveness. The mRNA of the 52K protease accumulates rapidly following estradiol treatment, as was shown by Northern blot analysis with cloned cDNA. The 52K cathepsin-D-like protease is the first example of a lysosomal protease induced by estrogens in cancer cells. Results obtained using different approaches suggest that two cysteinyl cathepsins are also related to cell transformation and invasiveness. It has been proposed that cathepsin-B is involved in breast cancer and metastatic melanoma, and its regulation by estrogen has been shown in the rat uterus. Cathepsin-L corresponds to the major excreted protein (MEP) whose synthesis and secretion are markedly increased by transformation of NIH 3T3 cells with Ki ras and are regulated by several growth factors. In addition to secreted autocrine growth factors and to other proteases (plasminogen activator, collagenase), lysosomal cathepsins may therefore play an important role in the process of tumor growth and invasion as long as their precursor is secreted abundantly.

Breast Neoplasms↗
PubMed1987

Phosphorylation, glycosylation, and proteolytic activity of the 52-kD estrogen-induced protein secreted by MCF7 cells.

We have studied the posttranslational modifications of the 52-kD protein, an estrogen-regulated autocrine mitogen secreted by several human breast cancer cells in culture (Westley, B., and H. Rochefort, 1980, Cell, 20:353-362). The secreted 52-kD protein was found to be phosphorylated mostly (94%) on high-mannose N-linked oligosaccharide chains, and mannose-6-phosphate signals were identified. The phosphate signal was totally removed by alkaline phosphatase hydrolysis. The secreted 52-kD protein was partly taken up by MCF7 cells via mannose-6-phosphate receptors and processed into 48- and 34-kD protein moieties as with lysosomal hydrolases. By electron microscopy, immunoperoxidase staining revealed most of the reactive proteins in lysosomes. After complete purification by immunoaffinity chromatography, we identified both the secreted 52-kD protein and its processed cellular forms as aspartic and acidic proteinases specifically inhibited by pepstatin. The 52-kD protease is secreted in breast cancer cells under its inactive proenzyme form, which can be autoactivated at acidic pH with a slight decrease of molecular mass. The enzyme of breast cancer cells, when compared with cathepsin D(s) of normal tissue, was found to be similar in molecular weight, enzymatic activities (inhibitors, substrates, specific activities), and immunoreactivity. However, the 52-kD protein and its cellular processed forms of breast cancer cells were totally sensitive to endo-beta-N-acetylglucosaminidase H (Endo H), whereas several cellular cathepsin D(s) of normal tissue were partially Endo H-resistant. This difference, in addition to others concerning tissue distribution, mitogenic activity and hormonal regulation, strongly suggests that the 52-kD cathepsin D-like enzyme of breast cancer cells is different from previously described cathepsin D(s). The 52-kD estrogen-induced lysosomal proteinase may have important functions in facilitating the mammary cancer cells to proliferate, migrate, and metastasize.

Breast Neoplasms↗