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Issakidis E, Lemaire M, Decottignies P, Jacquot JP, Miginiac-Maslow M. Direct evidence for the different roles of the N- and C-terminal regulatory disulfides of sorghum leaf NADP-malate dehydrogenase in its activation by reduced thioredoxin. FEBS Lett 1996; 392:121-4. [PMID: 8772188 DOI: 10.1016/0014-5793(96)00801-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Plant NADP-dependent malate dehydrogenase is activated through thiol/disulfide interchange with reduced thioredoxin. Previous studies showed that this process involves the reduction of two different disulfides per subunit: one N-terminal, the other C-terminal. Substitution of regulatory cysteines at each end by site-directed mutagenesis and comparison of activation kinetics of the mutants led us to propose a model for the activation mechanism where the C-terminal end shielded the access to the catalytic residues, whereas the N- terminal end was involved in the slow conformational change of the active site. In the present study, we took advantage of the previous identification of the catalytic histidine residue which can be specifically derivatized by diethyl pyrocarbonate to test the accessibility of the active site. The results clearly show that in the mutants where the C-terminal bridge is open the active site histidine is freely accessible to the reagent, whereas in the mutants where the N-terminal bridge is open, the active site cannot be reached without activation, thus demonstrating the validity of the model.
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Lemaire M, Bruelisauer A, Guntz P, Sato H. Dose-dependent brain penetration of SDZ PSC 833, a novel multidrug resistance-reversing cyclosporin, in rats. Cancer Chemother Pharmacol 1996; 38:481-6. [PMID: 8765444 DOI: 10.1007/s002800050515] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study quantitatively assessed the brain penetration of a potent P-glycoprotein inhibitor, SDZ PSC 833, and its effect on the blood-brain barrier (BBB) permeability (PS) of an anticancer agent, vincristine. At lower doses of SDZ PSC 833 the brain penetration, defined as the brain-to-blood partition coefficient (Kp), was very low in spite of the high lipophilicity of this compound. At higher doses, however, the brain penetration of SDZ PSC 833 was markedly increased. Since the blood pharmacokinetics of SDZ PSC 833 proved to be linear in the dose range studied, these results demonstrated a dose-dependent brain passage of SDZ PSC 833. The brain passage of cyclosporin A was also found to be dose-dependent. However, the potency of SDZ PSC 833 in inhibiting the efflux mechanism at the BBB was higher than that of cyclosporin A since 10 times higher doses of cyclosporin A were required to obtain the same Kp values recorded for SDZ PSC 833. Moreover, the coadministration of SDZ PSC 833 increased the brain penetration of cyclosporin A, whereas the latter did not modify that of SDZ PSC 833. The increase in SDZ PSC 833 and vincristine PS values observed at high blood levels of SDZ PSC 833 are consistent with the hypothesis of a saturation of the P-glycoprotein pump present at the BBB. The involvement of P-glycoprotein in the brain passage of SDZ PSC 833 could be of great significance for clinical application of the drug in the treatment of brain cancers when it is given in combination with anticancer agents.
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Meyer G, Lemaire M, Lyaku J, Pastoret PP, Thiry E. Establishment of a rabbit model for bovine herpesvirus type 5 neurological acute infection. Vet Microbiol 1996; 51:27-40. [PMID: 8828120 DOI: 10.1016/0378-1135(96)00016-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study was conducted to evaluate the suitability of the rabbit as a model for bovine, herpesvirus 5 (BHV-5) acute infection. In a preliminary experiment, a total of 24 one-month old New Zealand white rabbits were inoculated with BHV-5 or bovine herpesvirus 1 (BHV-1) by the intraconjunctival, intracerebral or intranasal routes. BHV-5 or BHV-1 inoculated in the conjunctiva induced virus proliferation in the eye mucosae and the nasal cavity of rabbits without meningo-encephalitis. On the other hand, only BHV-5 infection by intranasal or intracerebral routes produced a fatal meningo-encephalitis. The intranasal route was used in a further experiment for the establishment of a rabbit model for BHV-5 infection. A total of 45 rabbits were inoculated intranasally with BHV-5 or BHV-1. The results showed that intranasal inoculation of BHV-5 strain N569 in rabbits was followed by the development of a lethal meningo-encephalitis for 66% of rabbits while all BHV-1 infected rabbits remained healthy throughout this experiment (28 days). Analysis between the mortalities of rabbits infected with BHV-5 and BHV-1 were highly significant (p < 0.001). The presence of BHV-5 in the central nervous system (CNS) was confirmed by virus isolation (essentially the cerebrum, midbrain and pons) and by immunohistochemical staining of BHV-5 antigen (essentially in the neurons of the cerebrum) only in BHV-5 infected rabbits showing clinical signs of meningo-encephalitis. The findings obtained confirmed the suitability of a rabbit model for the establishment of BHV-5 neurological acute infection and also as a valuable tool for the comparative study of BHV-5 and BHV-1 neuropathogenicity.
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Nsouli B, Draye M, Allali H, Lemaire M, Thomas JP. Energy deposition and fragments production resulting from gamma-ray or ion beam irradiation of an ion exchange resin. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0168-1176(96)04381-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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130
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Béguin P, Lemaire M. The cellulosome: an exocellular, multiprotein complex specialized in cellulose degradation. Crit Rev Biochem Mol Biol 1996; 31:201-36. [PMID: 8817076 DOI: 10.3109/10409239609106584] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Clostridium thermocellum produces a highly active cellulase system that consists of a high-M(r) multienzyme complex termed cellulosome. Hydrolytic components of the cellulosome are organized around a large, noncatalytic glycoprotein termed CipA that acts both as a scaffolding component and a cellulose-binding factor. Catalytic subunits of the cellulosome bear conserved, noncatalytic subdomains, termed dockerin domains, which bind to receptor domains of CipA, termed cohesin domains. CipA includes nine cohesin domains, a cellulose-binding domain, and a specialized dockerin domain. Proteins of the cell envelope carrying cohesin domains that specifically bind the dockerin domain of CipA have been identified. These proteins may mediate anchoring of the cellulosomes to the cell surface. Cellulase complexes similar to the cellulosome of C. thermocellum are produced by several cellulolytic clostridia. High-M(r) multienzyme complexes have also been identified in anaerobic rumen fungi. The architecture of the fungal complexes also seems to rely on the interaction of conserved, noncatalytic docking domains with a scaffolding component. However, the sequence of the fungal docking domains bears no resemblance to the clostridial dockerin domains, suggesting that the fungal and clostridial complexes arose independently.
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Urwyler S, Campbell E, Fricker G, Jenner P, Lemaire M, McAllister KH, Neijt HC, Park CK, Perkins M, Rudin M, Sauter A, Smith L, Wiederhold KH, Müller W. Biphenyl-derivatives of 2-amino-7-phosphono-heptanoic acid, a novel class of potent competitive N-methyl-D-aspartate receptor antagonists--II. Pharmacological characterization in vivo. Neuropharmacology 1996; 35:655-69. [PMID: 8887975 DOI: 10.1016/0028-3908(96)84637-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A selection of biphenyl-analogues of 2-amino-7-phosphonoheptanoic acid (AP7), N-methyl-D-aspartate (NMDA) receptor antagonists with high affinity in vivo efficacy. The lead compound SDZ EAB 515 was found to inhibit L-phenylalanine uptake by the large neutral amino acid carrier in vitro and in vivo; active transport may thus confer a good bioavailability to this class of compounds. CNS effects were demonstrated by significant changes in 2-deoxyglucose-uptake in various brain regions at doses from 1 to 10 mg/kg i.p. With the most active agent, SDZ 220-581, full protection against maximal electroshock seizures (MES) was obtained at oral doses of 10 mg/kg in rats and in mice. The compound had a fast onset (< or = 1 hr) and a long duration (> or = 24 hr) of action. Motor-debilitating effects (impairment of rotarod performance) occurred at doses about 10 times higher than those required for protection against MES. Neuroprotective activity was demonstrated by the ability of the compounds to reduce the extent of quinolinic acid-induced striatal lesions in rats, in the dose range of 3-15 mg/kg (i.p.) or 10-50 mg/kg (p.o.). In the middle cerebral artery occlusion (MCAO) model of focal cerebral ischemia in rats, the test compounds reduced the infarct size by 40-50% when given i.v. before or by 20-30% when given i.v. 1 hr after MCAO. SDZ 220-581 provided 20-30% protection at > or = 2 x 10 mg/kg p.o. This compound also showed analgesic activity at low oral doses in a model of neuropathic pain, although higher doses were required in model of mechanical inflammatory hyperalgesia. Unexpectedly, SDZ 220-581 at low s.c. doses counteracted the antiparkinsonian effects of L-DOPA in MPTP-treated marmosets. (Sub)chronic administration of SDZ 220-581 did not reduce its ability to protect against quinolinic acid neurotoxicity, and no upregulation of NMDA receptors was detected using a [3H]CGP-39653 binding assay. In conclusion, from a series of biphenyl-AP7-derivatives, SDZ 220-581 is clearly the most active compound in vivo. Its pharmacological profile with a good, long-lasting oral activity might open up novel therapeutic applications for competitive NMDA receptor antagonists.
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Malhotra BK, Lemaire M, Brouillard JF, Sawchuk RJ. High-performance liquid chromatographic analysis of (S)-alpha-amino-5-phosphonomethyl[1,1'-biphenyl]-3-propanoic acid (EAB 515) in brain and blood microdialysate (on-line) and in plasma ultrafiltrate of freely moving rats. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 679:167-76. [PMID: 8998557 DOI: 10.1016/0378-4347(96)00020-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
(S)-alpha-Amino-5-phosphonomethyl[1,1'-biphenyl]-3-propanoic acid (EAB 515, I), a competitive antagonist of the N-methyl-D-aspartate receptor, has significant pharmacological activity in the central nervous system (CNS). An extremely sensitive and selective analytical method was developed for the simultaneous analysis of I and its hydroxylated analog (RDC, II) in the microdialysate (MD) and plasma ultrafiltrate (UF) of rats. Microdialysis was used for in vivo sampling of unbound drug in the CSF, cortical extracellular fluid and in the blood of freely moving rats. Compound II was used for retrodialysis-based in vivo calibration of microdialysis probes to estimate the recovery of I. Compound I, being extremely hydrophilic with a high degree of ionization at the physiological pH of 7.4, has limited access to the brain regions. This, combined with its low microdialysis recovery, made the estimation of low brain concentrations of I a challenge. The analytes in MD and UF were separated (within 5 min) by reversed-phase HPLC on a 250 x 4.6 mm I.D. Maxsil 5 microns RP-2 column, and fluorescence of the eluent was monitored at 255 nm (lambda ex) and 320 nm (lambda em). A 0.09% (v/v) aqueous solution of trifluoroacetic acid (1 ml/min) was used as the mobile phase. The response for I in MD and UF samples was linear from 5 to 2000 ng/ml and from 20 to 10,000 ng/ml, respectively. The between-run (n = 6) and within-run (n = 3) variability of the assay was < 15%. Plasma-protein binding of I (fu = 0.68) was determined to be linear from 0.1 to 10 micrograms/ml. The analytical sensitivity, precision and accuracy of this method was suitable for the characterization of the pharmacokinetics and the CNS distribution of I, following administration of intravenous (i.v.) infusion, single i.v. bolus and multiple i.v. bolus doses of I to freely moving rats, with continuous microdialysate sampling of multiple tissues and simultaneous on-line HPLC analysis. Pharmacokinetic parameters for I, as determined from concentrations in blood MD samples with on-line analysis, were in good agreement with those estimated from concentrations in the UF of plasma samples obtained by conventional sampling.
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Lemaire M, Miginiac-Maslow M, Decottignies P. The catalytic site of chloroplastic NADP-dependent malate dehydrogenase contains a His/Asp pair. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 236:947-52. [PMID: 8665917 DOI: 10.1111/j.1432-1033.1996.00947.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Plant chloroplastic NADP-malate dehydrogenase is unique among malate dehydrogenases because of its reductive activation in the light and cofactor specificity. In this paper, the role of His229 in sorghum leaf protein has been investigated by site-directed mutagenesis. His229 was replaced by Asn and Gln, both mutations yielding an inactive protein. The role of a conserved Asp (Asp201) as a possible partner of His229 in catalysis has been studied by the same approach. Both Asp mutants (D201A, D201N) were only slightly active and were essentially characterized by a dramatically increased Km for oxaloacetate (45-80-fold). pH dependence of catalytic rates revealed differences between the two Asp mutants. These results demonstrate that, in sorghum leaf NADP-dependent malate dehydrogenase, His229 is involved in catalysis in interaction with Asp201.
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Lemaire M, Issakidis E, Ruelland E, Decottignies P, Miginiac-Maslow M. An active-site cysteine of sorghum leaf NADP-malate dehydrogenase studied by site-directed mutagenesis. FEBS Lett 1996; 382:137-40. [PMID: 8612735 DOI: 10.1016/0014-5793(96)00153-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The chloroplast NADP-malate dehydrogenase is activated through the reduction of two different disulfides per subunit. The activated enzyme, as well as a permanently active mutant where all four regulatory cysteines were replaced are still sensitive to thiol reagents. This observation suggested the presence of an additional important cysteine at the active site. In an attempt to identify that cysteine, site-directed mutagenesis was performed on the cDNA encoding sorghum leaf NADP-malate dehydrogenase. The replacement of Cys-175 by an alanine yielded an enzyme whose sensitivity to thiol reagents was markedly decreased whereas its catalytic activity was enhanced. This finding suggests that Cys-175 has no catalytic function but is located close to the active site.
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van Amsterdam C, Boukhabza A, Ofner B, Pacha W, Lemaire M. Measurement of free concentration of SDZ ICM 567 in blood and muscle using microdialysis sampling. Biopharm Drug Dispos 1995; 16:521-7. [PMID: 7579033 DOI: 10.1002/bdd.2510160609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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137
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Lemaire M, Meyer G, Ernst E, Vanherreweghe V, Limbourg B, Pastoret PP, Thiry E. Latent bovine herpesvirus 1 infection in calves protected by colostral immunity. Vet Rec 1995; 137:70-1. [PMID: 8533236 DOI: 10.1136/vr.137.3.70] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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138
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Poynard T, Lemaire M, Agostini H. Meta-analysis of randomized clinical trials comparing lansoprazole with ranitidine or famotidine in the treatment of acute duodenal ulcer. Eur J Gastroenterol Hepatol 1995; 7:661-5. [PMID: 8590162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVE The aim was to compare the clinical efficacy of lansoprazole with the efficacies of ranitidine and famotidine in order to rank this drug in the hierarchy of duodenal ulcer treatments. METHODS All randomized clinical trials in which lansoprazole was used to treat patients with duodenal ulceration were reviewed. The meta-analysis included a quality assessment for each trial. The main criterion chosen for the meta-analysis was the endoscopic healing rate at 4 weeks; other criteria were the healing rate at 2 weeks and the absence of pain at 2 and 4 weeks. Statistical methods used were the Der Simonian and Laird method and the method of Peto et al. A sensitivity analysis was performed according to the H2 blocker type (famotidine or ranitidine). Odds ratios against histamine-receptor blockers were used to compare lansoprazole indirectly with omeprazole and other drugs. RESULTS Five double-blind trials were identified including 848 patients. The mean 4-week healing rate in patients treated with lansoprazole was 85%, which was significantly higher than the healing rate in patients treated with H2-receptor blockers (75%). This difference of 10% was significant (P < 0.01) according to the Der Simonian method, and the corresponding odds ratio of 2.27 (95% confidence interval 1.5-3.2) was significant according to the Peto method (P < 0.01). There was also a significant difference in favour of lansoprazole for 2-week healing rates (mean difference 20%, P < 0.01) and for the percentage of patients without pain at 2 weeks (mean difference 8%; P < 0.02). Indirect comparisons of 4-week healing rates showed no difference between 30 mg lansoprazole and 20 mg omeprazole and confirmed that both drugs had a greater efficacy than ranitidine, famotidine, nizitidine, cimetidine or sucralfate. CONCLUSION This meta-analysis showed that 30 mg lansoprazole was more effective in producing healing at 2 and 4 weeks than ranitidine or famotidine. Lansoprazole also led to a greater reduction in the percentage of patients free of pain at 2 weeks. The efficacy of lansoprazole was not different from that of omeprazole.
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Lemaire M, Ohayon H, Gounon P, Fujino T, Béguin P. OlpB, a new outer layer protein of Clostridium thermocellum, and binding of its S-layer-like domains to components of the cell envelope. J Bacteriol 1995; 177:2451-9. [PMID: 7730277 PMCID: PMC176904 DOI: 10.1128/jb.177.9.2451-2459.1995] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Several proteins of Clostridium thermocellum possess a C-terminal triplicated sequence related to bacterial cell surface proteins. This sequence was named the SLH domain (for S-layer homology), and it was proposed that it might serve to anchor proteins to the cell surface (A. Lupas, H. Engelhardt, J. Peters, U. Santarius, S. Volker, and W. Baumeister, J. Bacteriol. 176:1224-1233, 1994). This hypothesis was investigated by using the SLH-containing protein ORF1p from C. thermocellum as a model. Subcellular fractionation, immunoblotting, and electron microscopy of immunocytochemically labeled cells indicated that ORF1p was located on the surface of C. thermocellum. To detect C. thermocellum components interacting with the SLH domains of ORF1p, a probe was constructed by grafting these domains on the C terminus of the MalE protein of Escherichia coli. The SLH domains conferred on the chimeric protein (MalE-ORF1p-C) the ability to bind noncovalently to the peptidoglycan of C. thermocellum. In addition, 125I-labeled MalE-ORF1p-C was shown to bind to SLH-bearing proteins transferred onto nitrocellulose, and to a 26- to 28-kDa component of the cell envelope. These results agree with the hypothesis that SLH domains contribute to the binding of exocellular proteins to the cell surface of bacteria. The gene carrying ORF1 and its product, ORF1p, are renamed olpB and OlpB (for outer layer protein B), respectively.
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Charnick SB, Kawai R, Nedelman JR, Lemaire M, Niederberger W, Sato H. Perspectives in pharmacokinetics. Physiologically based pharmacokinetic modeling as a tool for drug development. JOURNAL OF PHARMACOKINETICS AND BIOPHARMACEUTICS 1995; 23:217-29. [PMID: 8719238 DOI: 10.1007/bf02354273] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Since the pioneering work of Haggard and Teorell in the first half of the 20th century, and of Bischoff and Dedrick in the late 1960s, physiologically based pharmacokinetic (PBPK) modeling has gone through cycles of general acceptance, and of healthy skepticism. Recently, however, the trend in the pharmaceuticals industry has been away from PBPK models. This is understandable when one considers the time and effort necessary to develop, test, and implement a typical PBPK model, and the fact that in the present-day environment for drug development, efficacy and safety must be demonstrated and drugs brought to market more rapidly. Although there are many modeling tools available to the pharmacokineticist today, many of which are preferable to PBPK modeling in most circumstances, there are several situations in which PBPK modeling provides distinct benefits that outweigh the drawbacks of increased time and effort for implementation. In this Commentary, we draw on our experience with this modeling technique in an industry setting to provide guidelines on when PBPK modeling techniques could be applied in an industrial setting to satisfy the needs of regulatory customers. We hope these guidelines will assist researchers in deciding when to apply PBPK modeling techniques. It is our contention that PBPK modeling should be viewed as one of many modeling tools for drug development.
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141
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Guyon V, Foos J, Guy A, Moutarde T, Chomel R, Draye M, Lemaire M. Synthesis and Utilization of New Extractants for Nuclear Hydrometallurgy. SEP SCI TECHNOL 1995. [DOI: 10.1080/01496399508010388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Draye M, Lemaire M, Chevillotte R, Chomel R, Doutreluingne P, Foos J, Guy A. Use of a Cross-Linked Poly(4-Vinylpyridine) for Nuclear Waste Treatment. SEP SCI TECHNOL 1995. [DOI: 10.1080/01496399508010344] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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143
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Guyon V, Guy A, Foos J, Lemaire M, Draye M. Lipophilic polythiamacrocycles as palladium extracting agents. Tetrahedron 1995. [DOI: 10.1016/0040-4020(95)00147-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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144
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Alonso MJ, Bruelisauer A, Misslin P, Lemaire M. Microdialysis sampling to determine the pharmacokinetics of unbound SDZ ICM 567 in blood and brain in awake, freely-moving rats. Pharm Res 1995; 12:291-4. [PMID: 7784347 DOI: 10.1023/a:1016247413935] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The free concentrations of the serotoninergic 5-HT3 antagonist SDZ ICM 567 in blood and in the central nervous system were examined in awake, freely-moving rats using blood and brain microdialysis coupled to liquid chromatography. Microdialysis probes were implanted in the jugular vein and in the frontal cortex and dialysis samples were simultaneously collected from both sites. Pharmacokinetic parameters were calculated after a 10 mg/kg intravenous dose of [14C]SDZ ICM 567. The elimination half lives measured in whole blood, brain and blood microdialysates were similar (congruent to 1.7 h). The AUC0-5h corresponding to the unbound drug was 462 +/- 142 ng.ml-1.h in blood dialysate, not significantly different from the AUC corresponding to the free concentration in whole blood, i.e. 586 +/- 63 ng.ml-1.h. The free fraction in blood obtained in vitro by equilibrium dialysis (21%) or by microdialysis (19%) was not statistically different from that obtained in vivo (17%) in microdialysis experiments. The unbound concentrations (AUC0-5h) of SDZ ICM 567 in the brain cortex were 86 +/- 24 ng.ml-1.h, lower than those expected from unbound blood concentrations, suggesting an active transport out of the central nervous system. Finally, microdialysis sampling allowed the determination of pharmacokinetic parameters of SDZ ICM 567 in blood and brain as well as the estimation of the free fraction of drug in blood.
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Léonard A, Baugnet-Mahieu L, Hung TH, Léonard ED, Lemaire M, Gerber GB. Chromosome aberrations in circulating lymphocytes after brachytherapy for uterus carcinoma. Acta Oncol 1995; 34:540-2. [PMID: 7605668 DOI: 10.3109/02841869509094024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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146
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Jacquot JP, Issakidis E, Decottignies P, Lemaire M, Miginiac-Maslow M. Analysis and manipulation of target enzymes for thioredoxin control. Methods Enzymol 1995; 252:240-52. [PMID: 7476358 DOI: 10.1016/0076-6879(95)52027-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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147
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Terasaki T, Mizuguchi H, Itoho C, Tamai I, Lemaire M, Tsuji A. Hepatic uptake of octreotide, a long-acting somatostatin analogue, via a bile acid transport system. Pharm Res 1995; 12:12-7. [PMID: 7724472 DOI: 10.1023/a:1016222217067] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The hepatic transport mechanism of octreotide (Sandostatin), a somatostatin analogue, was studied using freshly prepared rat hepatocytes. The initial uptake rate of octreotide represented exclusively a saturable transport process. The half-saturation constant, Kt, and the maximum uptake-rate, Jmax, for the uptake of octreotide were 91.1 +/- 28.4 microM and 104.6 +/- 19.7 pmol/mg protein/min, respectively. An energy requirement was demonstrated for [14C]octreotide uptake since metabolic inhibitors (DNP, rotenone, antimycin and NaCN) significantly reduced the initial uptake rate. [14C]octreotide uptake was also significantly inhibited by ouabain. [14C]octreotide uptake was reduced in the absence of Na+ in the uptake medium. [14C]octreotide uptake was significantly inhibited by bile acids, iodipamide, d-tubocurarine, whereas it was not inhibited by bilirubin, TEMA and insulin. Competitive inhibition of taurocholic acid was observed for octreotide uptake with the inhibition constant, Ki, of 82 +/- 17 microM. Moreover, a significant inhibitory effect of octreotide was observed for the Na+ dependent uptake of [14C]taurocholic acid. These results suggest that octreotide is transported into hepatocytes via a bile acid carrier-mediated system.
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148
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Baugnet-Mahieu L, Lemaire M, Léonard ED, Léonard A, Gerber GB, Leonard ED, Leonard A. Chromosome Aberrations after Treatment with Radioactive Iodine for Thyroid Cancer. Radiat Res 1994. [DOI: 10.2307/3579122] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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149
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Baugnet-Mahieu L, Lemaire M, Léonard ED, Léonard A, Gerber GB. Chromosome aberrations after treatment with radioactive iodine for thyroid cancer. Radiat Res 1994; 140:429-31. [PMID: 7972697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The study aimed to investigate whether the determination of chromosome aberrations in circulating blood lymphocytes could be useful to assess whole-body exposure from radioactive iodine released accidentally. Ten patients treated with two doses of 1850 MBq of 131I given 24 h apart for thyroid cancer were studied for chromosome aberrations (dicentrics) in blood samples taken before and at various times after exposure. The increase in the yield of aberrations caused by the exposure to iodine was small but statistically significant. Compared to published values for whole-body doses after such treatment, this increase appears to be somewhat smaller than expected from dose-effect relationships obtained for an acute exposure of lymphocytes in vitro or in vivo, a fact which could be explained by the low dose rate of the 131I exposure. Thus, in situations where a population was exposed as a result of the release of radioactive iodine, a determination of chromosome aberrations in blood lymphocytes would not appear to be very useful to determine exposure from iodine.
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Lemaire M, Schmitter JM, Issakidis E, Miginiac-Maslow M, Gadal P, Decottignies P. Essential histidine at the active site of sorghum leaf NADP-dependent malate dehydrogenase. J Biol Chem 1994; 269:27291-6. [PMID: 7961639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Chloroplastic NADP-dependent malate dehydrogenase (NADP-MDH) is a key enzyme in the photosynthetic CO2 fixation pathway of C4-plants. The presence of a histidine at its active site has been proposed, based on sequence alignment with nonchloroplastic NAD-dependent malate dehydrogenases. In order to investigate this hypothesis, the effect of diethylpyrocarbonate on the sorghum leaf enzyme has been tested. Diethylpyrocarbonate strongly inhibited NADP-MDH activity, its effect being dramatically decreased in the presence of substrates and reversed by hydroxylamine. When diethylpyrocarbonate-inactivated NADP-MDH was cleaved with trypsin, one peptide with increased absorbance at 240 nm was detected. Sequencing of this peptide and analysis by mass spectrometry demonstrated that histidine 229 was modified by diethylpyrocarbonate. This amino acid was changed to an alanine by site-directed mutagenesis, and the modified protein was produced in Escherichia coli. It was similar to the plant enzyme except that it was totally inactive. Taken together, these results indicate that His229 is an essential residue in the active site of sorghum NADP-MDH.
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