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R Julien

Publications and source records attributed to R Julien.

At least 73 records · Page 4Linked to original sources
PubMed1991

Evidence for a ribosome-associated thiol protease cleaving wheat germ methionyl-tRNA synthetase.

A wheat germ protease is responsible for Mr 105,000 methionyl-tRNA synthetase hydrolysis, generating two fragments of Mr 82,000 (harbouring the catalytic domain) and 20,000, respectively. Specificity of the protease was sought for using different kinds of protein substrates. It turned out that charged peptides were preferentially cleaved and that no proteolysis occurred when proteins were replaced by small synthetic substrates, harbouring target sites similar to those cleaved in proteins. The protease could be a ribosomal protein, since it remained associated to ribosomal structure, even after treatment by deoxycholate, Triton X-100, 800 mM KC1 and puromycin. Nevertheless, it was still active after ribonuclease treatment of the ribosomes. An identical protease activity was found in rat liver, but not in E. coli.

Chromatography, Gel↗
PubMed1991

Evaluation of 2-methoxyacetic acid toxicity on mouse germ cells by flow cytometry.

Flow cytometric (FCM) DNA content measurements were carried out on testicular monocellular suspensions obtained from mice exposed per os to a single dose of 50, 100, 300, 600, and 900 mg/kg body weight (b.w.) of 2-methoxyacetic acid (MAA) in order to investigate its cytotoxic action on germ cells. The effects of MAA were evaluated 2, 7, 14, 28, and 45 d after treatment in terms of altered cell type ratios in FCM fluorescence distribution histograms. Testis weight and histological tissue sections were also analyzed. MAA induced marked changes in the relative percentages of tetraploid and haploid cells, indicating the occurrence of cytotoxic damage on primary spermatocytes. Multiparameter FCM analysis showed that, besides its action on nucleic acid synthesis, MAA can also affect the cellular energy metabolism reflected in an altered mitochondrial mass distribution on round spermatids surviving the MAA treatment. This study demonstrates that rapid and unique FCM procedures can be usefully applied in reproductive toxicology.

Acetates↗
PubMed1991

Immunochemical determination of porcine pancreatic colipase: differentiation between procolipase and its trypsin-activated form.

A noncompetitive enzyme-linked immunosorbent assay (ELISA) has been developed for the quantitative determination of porcine pancreatic colipase. Calibration curves were established by coating polystyrene immunoplates with pure procolipase or its trypsin-activated derivative. Bound antigen was detected with antiporcine procolipase polyclonal antibodies. Under optimizing conditions, the minimal detectable amount of porcine colipase was 0.1 ng, which is about 1,000 times less than the minimal amount that can be assayed titrimetrically. The useful range of the immunoassay was between 0.1 to 1 ng (2-20 micrograms/L). Under standard assay conditions, no distinction can be made between the precursor and activated forms of the cofactor. Results of immunochemical determinations of colipase in porcine pancreatic juice and tissue extract were in good agreement with those obtained with the potentiometric method. The specific determination of activated colipase in pancreatic juice was performed by coating the immunoplates with antigen in solution in PBS with 0.5 g/L of Tween 20. The detergent selectively impaired the binding of procolipase to the plate. Determination of colipase in human pancreatic juice carried out under the same experimental conditions showed that the minimal amount of human cofactor detectable with ELISA was 1 ng due to partial immunological crossreactivity of the human and porcine proteins. Immunoassay performed with antiporcine procolipase monoclonal antibodies (Mab) showed lower sensitivity than that performed with polyclonal antibodies. However, Mab 72.11, a monoclonal antibody that reacted only with porcine procolipase, allowed specific detection and differential determination of the precursor form of porcine colipase in pancreatic juice. ELISA performed with pure human colipase indicated that no antiporcine procolipase monoclonal antibodies cross-reacted with the human cofactor.

Animals↗
PubMed1991

Adhesion of K99 fimbriated Escherichia coli to pig intestinal epithelium: correlation of adhesive and non-adhesive phenotypes with the sialoglycolipid content.

Evidence for the existence of two phenotypes of piglets born to experimental herds was obtained based on the susceptibility of intestinal brush borders to adhesion of K99-positive Escherichia coli. The enterocytes of the K99-receptive piglets displayed a characteristic sialoglycolipid pattern, with a higher content of the monosialoglycolipids II3NeuGc-LacCer (GM3Gc), IV3NeuGc-nLcOse4Cer (SPGGc) and IV3NeuAc-nLcOse4Cer (SPG) and the oligosialogangliosides IV3NeuAc,II3NeuAc-GgOse4Cer (GD1a), II3(NeuAc)2-GgOse3Cer (GD2), II3(NeuAc)2-GgOse4Cer (GD1b) and IV3NeuAc,II3(NeuAc)2-GgOse4Cer (GT1b) when compared to the gangliosides of non-receptive piglets. The gangliosides from enterocytes of the non-receptive piglets were mainly the monosialogangliosides II3NeuAc-GgOse3Cer (GM2) and II3NeuAc-LacCer (GM3), only traces of the other sialoglycolipids being detected. Adhesion of 14C-labelled K99-positive E. coli cells to the piglet small intestinal sialoglycolipids, as tested by the thin-layer chromatogram overlay assay, revealed that the receptive enterocyte membrane was richer in glycolipids containing K99 receptor structures than the non-receptive enterocyte. Adhesion of K99-positive E. coli correlated with the degree of sialylation of the brush border glycolipids.

Animals↗
PubMed1990

Purified internal G-domain of translational initiation factor IF-2 displays guanine nucleotide binding properties.

Translational initiation factor IF-2 is involved in a multistep pathway leading to the synthesis of the first peptide bond. IF-2 is a guanine nucleotide binding protein (G-protein) and catalyzes GTP hydrolysis in the presence of ribosomes. According to sequence homologies with other G-proteins, particularly EF-Tu, a theoretical model for the tertiary structure of the putative G-domain of IF-2 has been previously proposed [Cenatiempo, Y., Deville, F., Dondon, J., Grunberg-Manago, M., Hershey, J. W. B., Hansen, H. F., Petersen, H. U., Clark, B. F. C., Kjeldgaard, M., La Cour, T. F. M., Mortensen, K. K., & Nyborg, J. (1987) Biochemistry 26, 5070-5076]. A short fragment of IF-2 encompassing the putative G-domain was purified by limited proteolysis of a chimeric protein, synthesized from a gene fusion, between a segment of the IF-2 gene and lacZ. The N- and C-terminal sequences of this IF-2 peptide were characterized. Its calculated length is 181 amino acids and its molecular mass 19.4 kDa, whereas it migrates at 14 kDa in SDS-polyacrylamide gels. This segment of IF-2 can form binary complexes with GDP and can be cross-linked to GTP, therefore indicating that it really corresponds to the G-domain. However, in contrast to the situation described for the purified G-domain of EF-Tu, the IF-2 fragment did not hydrolyze GTP even in the presence of ribosomes. It is assumed that active centers of IF-2 located outside the G-domain are needed for the latter reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

A new method for testing cell ageing using two mitochondria specific fluorescent probes.

Cell culture techniques have considerably improved our understanding of the numerous changes related to aging. For instance, murine lymphocytes obtained from animals older than 6 months progressively lose their, in vitro, proliferative capacity. Numerous studies have shown that this loss is due to changes in the mitochondrial compartment such as reduction in the transmembrane potential and/or membrane mass. Using two mitochondria specific probes with a potential-dependent (Rhodamine 123) or independent (Nonyl Acridine Orange) uptake, we found that the decline in the respiratory activity in the mouse occurred approximately 6 months prior to the decrease in mitochondrial membrane mass. The analysis of the Rh 123/NAO fluorescence ratio measured in splenocytes obtained from mice aged more than 6 months, showed that there was a linear loss of respiratory efficiency per unit of mitochondrial membrane mass. Moreover, cells with a ratio of less than 0.85 were incapable of proliferating and remained quiescent. The time separating the infection points of the two dye uptake curves might provide informations about the regulation and coordination of nuclear and/or mitochondrial genomes. Moreover, the ratio between the two fluorescent probes, in particular during the linear phase, may also have a predictive value.

Acridine Orange↗
PubMed1990

Specific interaction of the new fluorescent dye 10-N-nonyl acridine orange with inner mitochondrial membrane. A lipid-mediated inhibition of oxidative phosphorylation.

The fluorescent dye 10-N-nonyl acridine orange (NAO), known as specifically associated with mitochondria, has been reported to have a cytotoxic effect when high doses were applied to cells. Presently, the biochemical basis of its toxicity was investigated on isolated rat liver mitochondria. At low concentrations, NAO strongly inhibited state 3 respiration and ATP synthesis. At high concentrations, electron transport, ATP hydrolysis, Pi-transport and adenine nucleotide activities were also decreased. All these inhibitions can be explained by probe-cardiolipin interactions which could induce the collapse of energy conversion and/or the modification of membrane fluidity.

Acridine Orange↗
PubMed1990

Comparative flow cytometric analysis of bleomycin toxicity on normal and tumour sheep cell kinetics in vitro.

The cytotoxic effects of bleomycin on cell proliferation, morphology and cycle progression were compared in a sheep tumour cell line and in normal sheep sinus cells. They were concentration and time dependent, irreversible, and were accompanied by increased cell diameter and cytosolic synthetic activity. Cell accumulation in the G2M phase, without much change in the cell cycle progression through the S phase, was observed using flow cytometry. Although the tumour cells showed a greater sensitivity to low bleomycin concentrations compared to the normal cells, both cell types exhibited equal sensitivity to higher drug concentrations. Provided that tumour cells are also preferentially affected by bleomycin in vivo, these findings raise the possibility that bleomycin cytotoxicity can be reduced or avoided in normal tissue.

Animals↗
PubMed1990

3-Amino-6-methoxy-9-(2-hydroxyethylamino) acridine: a new fluorescent dye to detect Mycoplasma contamination in cell cultures.

A new fluorescent acridine orange derivative, 3-amino-6-methoxy-9-(2-hydroxyethylamino) acridine (AMHA), has been applied to Hela cells in order to set up appropriate conditions for the detection of mycoplasma contaminations. Since AMHA staining reveals intensely fluorescent nuclei and slight fluorescent cytoplasm, we can visualize and localize mycoplasma contamination on each cell. In combination with a shortened Chen's staining method (1977), AMHA should allow a better detection of mycoplasma in animal cell cultures than the well established Hoechst dye.

Aminoacridines↗
PubMed1990

Severe acne due to chronic amineptine overdose.

We report six women with severe acne lesions associated with taking amineptine, a tricyclic antidepressant. The lesions appeared after self-administration of high doses of the drug over long periods of time. They mainly occurred on the face, back, and thorax, but were also found on the extremities and in the perineal region. In five of the six cases, severity of cutaneous lesions appeared to be correlated with degree of overdose. The sixth patient never admitted having taken amineptine. Most of the patients had been unsuccessfully treated with isotretinoin for 18 months. In all six cases, chromatography of urinary 17-ketosteroids showed abnormal peaks and retention times which were different from those usually found for known steroids. In addition, the areas under these peaks were found to be a function of the degree of intoxication and of the clinical severity of the lesions. Mass spectrometry was used to qualitatively study urinary amineptine metabolites, disclosing compounds normally found only in trace amounts, as well as certain others heretofore not described in man. In two of the three patients who stopped taking amineptine, cutaneous lesions subsequently diminished, totally disappearing in the least severe case.

Acne Vulgaris↗
PubMed1990

Use of nonyl acridine orange and rhodamine 123 to follow biosynthesis and functional assembly of mitochondrial membrane during L1210 cell cycle.

Specific mitochondrial incorporation of 10 N-nonyl acridine orange (NAO) is demonstrated by subcellular fractionation of rat hepatocytes. Moreover, comparative studies with NAO and rhodamine 123 (Rh 123) prove that acridine orange-derivative uptake is independent of transmembrane mitochondrial potential, a property allowing its utilization for the assessment of mitochondrial membrane mass modifications under various physiological states. Using NAO and Rh 123, we have respectively followed the biosynthesis of mitochondrial membrane and its assembly under a functional state during the L1210 cell cycle. Their evolution occurs in two stages according to a well-defined sequential order. Mitochondrial biogenesis, as revealed by NAO incorporation, occurs essentially in the G1 phase (probably mitochondrion enlargement) but also starts in late S phase (probably mitochondrion division). The increased amount of functional mitochondrial membrane, monitored by Rh 123 uptake, is emphasized in late G1 (prerequisite to DNA synthesis) and during G2M phases (prerequisite to mitosis). This alternative succession of phases displays the existence of a time-lag between the biosynthesis of mitochondrial membrane and its functional organization. Such an analysis confirms the potential of the NAO probe to evaluate mitochondrial membrane mass changes in various biological fields.

Acridine Orange↗
PubMed1990

Increase in plasma 5 alpha-androstane-3 alpha,17 beta-diol glucuronide as a marker of peripheral androgen action in hirsutism: a side-effect induced by cyclosporine A.

Dose-dependent hypertrichosis is a common dermatological side-effect affecting the majority of patients treated with cyclosporine A (CSA). Previous studies have not demonstrated the influence of CSA on specific sex hormone levels. The aim of this study is to investigate whether CSA increases the activity of 5 alpha-reductase, an enzyme which transforms androgens into dihydrotestosterone in peripheral tissues. The metabolite which best reflects this activity is 5 alpha-androstane-3 alpha,17 beta-diol glucuronide (Adiol G). The study was carried out on 49 insulin-dependent diabetes patients participating in the double-blind "Cyclosporine-Diabète-France" clinical trial, of which 28 were treated with CSA (16 males and 12 females), and 21 received only placebo (10 males and 11 females). All patients underwent extensive clinical and laboratory evaluations prior to and during the present study. In addition to Adiol G, testosterone (T), dehydroepiandrosterone sulfate (DHEA S) and sex hormone-binding globulin (SHBG) were assayed. Levels of Adiol G increased significantly in CSA-treated groups: males, 11.86 +/- 2.58 vs 7.83 +/- 2.30 nmol/l; females, 4.48 +/- 2.70 vs 2.10 +/- 1.22 nmol/l; P less than 0.02 (comparison of means). There were no significant differences in this parameter before and during treatment in either the male or female placebo groups (paired t-test). During the treatment period, T, DHEA S, SHBG and the T/SHBG ratio did not significantly change with respect to their baseline values in any of the groups studied (comparison of means). Comparison (using paired t-test) showed a significant increase of DHEA S in CSA-treated groups: males, delta = 3.08 +/- 3.33 nmol/l, P less than 0.01; females, delta = 0.98 +/- 1.13 nmol/l, P less than 0.05. In conclusion, it is possible that CSA induces hypertrichosis or hirsutism by increasing 5 alpha-reductase activity in peripheral tissues. Nevertheless the role of increased DHEA S as a possible Adiol G precursor cannot be excluded.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1990

Androgen excess in women with acne alone compared with women with acne and/or hirsutism.

Acne is known to be one of the features of hyperandrogenism. The aim of the present work was to study women with persistent acne and without other evidence of hyperandrogenism, such as hirsutism, alopecia, or irregular menses. Among 87 female patients with acne and/or hirsutism, we defined three groups: group 1 (n = 29), patients having treatment-resistant acne without menstrual disturbance, alopecia, or hirsutism; group 2 (n = 27), patients with acne and hirsutism; and group 3 (n = 31), patients with hirsutism alone. Clinical chemistry criteria for hyperandrogenism were based on elevated values of one or more of the following parameters: plasma testosterone, delta-4-androstenedione, dehydroepiandrosterone, urinary 5 alpha-androstane 3 alpha-17 beta-diol, and 17-ketosteroids (with chromatography). Plasma and urine samples were drawn between the 18th and 25th days of the cycle. Among group 1 patients, we found 25 subjects (86%) with hyperandrogenism, according to these laboratory criteria. The etiologies were: polycystic ovary syndrome (36%), adrenal hypersecretion (40%, of which 12% showed secondary polycystic ovaries), isolated increase in 5 alpha-androstane 3 alpha-17 beta-diol (20%), and hyperandrogenism without diagnosis (4%). The parameters were found to be more elevated in these patients than in a control group of 30 normal volunteer women. In groups 2 and 3, the findings were essentially the same as in group 1, except for increased levels of testosterone and the testosterone/SHBG ratio. Furthermore, it was evident that persistent acne may be an isolated sign of hyperandrogenism.

Acne Vulgaris↗
PubMed1990

Glycoprotein glycans that inhibit adhesion of Escherichia coli mediated by K99 fimbriae: treatment of experimental colibacillosis.

Calf diarrhea due to infection by enterotoxigenic Escherichia coli was treated by administration of glycoprotein glycans derived from bovine plasma. The glycan moieties of the nonimmunoglobulin fraction of plasma mimicked the oligosaccharide moiety of intestinal receptors recognized by K99 pili. These glycoprotein glycans inhibited adhesion of E. coli K99+ ST+ to erythrocyte glycoconjugates in vitro, and they protected colostrum-deprived newborn calves against lethal doses of enterotoxigenic E. coli (10(10) bacteria). Adhesion of bacteria to the intestines (duodenum, jejunum, and ileum) was significantly reduced (by 2 orders of magnitude) in treated calves.

Animals↗
PubMed1989

10-N nonyl-acridine orange: a fluorescent probe which stains mitochondria independently of their energetic state.

The specificity of binding of 10-N Nonyl Acridine Orange to mitochondria, and more precisely to inner membranes, is demonstrated by subcellular fractionation of hepatocytes. Unlike Rhodamine 123, which is a preferential marker of the transmembrane potential, Nonyl Acridine Orange binding is essentially independent of the mitochondria energization state although a low uptake of this dye, in response to the potential, may be measured. So 10-N Nonyl acridine orange is an appropriate marker of the mitochondial membrane surface per unit of cell mass.

Acridine Orange↗
PubMed1989

Increased plasma 21-deoxycorticosterone (21-DB) levels in late-onset adrenal 21-hydroxylase deficiency suggest a mild defect of the mineralocorticoid pathway.

Plasma 21-deoxycorticosterone (21-DB) concentrations were measured before (basal) and 1 h after ACTH stimulation in a population of 34 normal subjects, 18 patients with the late-onset form of congenital adrenal hyperplasia (LO-CAH) due to 21-hydroxylase deficiency, and 19 LOCAH heterozygotes. For comparison, plasma 21-deoxycortisol (21-DOF) and 17-hydroxyprogesterone (17-OHP) were determined simultaneously in the same subjects. Plasma 21-DB concentrations as well as those of 21-DOF did not vary significantly as a function of age, sex, or phase of the menstrual cycle, in contrast to plasma 17-OHP. The mean plasma 21-DB concentrations in normal subjects (adult men, follicular and luteal phase women, and children) were 19.0 +/- 9.5 (+/- SD) pmol/L before and 73.2 +/- 31.0 after ACTH stimulation. In the LOCAH patient group, the mean post-ACTH plasma 21-DB concentration was 1736.0 +/- 1243.0 pmol/L, and all values were above the highest post-ACTH value (148.2 pmol/L) in the normal subjects. Similarly, in the LOCAH patients the post-ACTH plasma 21-DOF concentration was 33.7 +/- 20.3 nmol/L, and the post-ACTH plasma 17-OHP value was 134.0 +/- 70.6 nmol/L; all LOCAH patients had supranormal responses to ACTH. However, 38.9%, 11.2% and 16.7% of the basal plasma 21-DB, 21-DOF, and 17-OHP values in the LOCAH patients overlapped those in the normal subjects. There was a rather large overlap (63.2%) in post-ACTH plasma 21-DB levels between the LOCAH heterozygotes and the normal subjects; it was less than the overlap in plasma 17-OHP (74%) and more than the overlap in plasma 21-DOF values (5.2%) in these same 2 groups. There was moderate overlap (21%) in the post-ACTH plasma 21-DB levels between the LOCAH heterozygotes and LOCAH patients, but no overlap between these 2 groups for either 21-DOF or 17-OHP. The abnormally elevated post-ACTH plasma 21-DB levels found in all the LOCAH patients as well as in some LOCAH heterozygotes suggest the existence of minor 21-hydroxylase deficiency in the mineralocorticoid synthetic pathway in these patients in addition to the well known impairment in the glucocorticoid pathway demonstrated by the elevated post-ACTH 21-DOF and 17-OHP levels.

17-alpha-Hydroxyprogesterone↗
PubMed1989

[Effect of estroprogestative drugs on the secretion of corticoadrenal hormones].

Estro-progestative drugs (EPD) have been used for many years and multiple secondary effects have been reported concerning mainly the glucidic and lipidic metabolisms. Effects of EPD on steroid metabolism have also been described and the authors present a review of the literature on this subject. Particularly it appears that EPD affect: the glucocorticoid metabolism, with augmentation of total cortisol although not in its free-form (augmentation of transcortine), the adrenal androgens metabolism, with diminution of their circulating rates, the aldosterone metabolism with augmentation of its secretion. These biological constatations could help explaining some clinical features occurring with administration of EPD: diminution of hirsutism and/or acne, augmentation of body weight, appearance of hypertension.

Adrenal Cortex Hormones↗