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Biomedical subjects

B Toussaint

Publications and source records attributed to B Toussaint.

At least 37 records · Page 2Linked to original sources
PubMed2000

Protein delivery by Pseudomonas type III secretion system: Ex vivo complementation of p67(phox)-deficient chronic granulomatous disease.

Bacterial type III secretion system drives the translocation of virulence factors into the cystosol of host target cells. In phagocytes and in Epstein-Barr virus immortalized B lymphocytes, NADPH oxidase generates O(-2) through an electron transfer chain the activity of which depends on the assembly of three, p67(phox), p47(phox) and p40(phox) cytosolic activating factors with Rac 1/2 and a membrane redox component, cytochrome b(558). In p67(phox) deficient chronic granulomatous disease (CGD) patients, p67-phox is missing and NADPH oxidase activity is abolished. ExoS is a virulence factor of Pseudomonas aeruginosa which is secreted via the type III secretion system: it was fused with p67(phox). Pseudomonas aeruginosa synthesized and translocated the hybrid ExoS-p67(phox) fusion protein into the cytosol of B lymphocytes via the type III secretion system. Purified ExoS-p67(phox) hybrid protein was as efficient as normal recombinant p67(phox) in cell-free reconstitution of NADPH oxidase activity. Therefore, ExoS-p67(phox) was transferred via the type III secretion system of Pseudomonas aeruginosa into the cytosol of B lymphocytes from a p67(phox)-deficient CGD patient and functionally reconstituted NADPH oxidase activity. In the complementation process, ExoS acted as a molecular courier for protein delivery: the reconstitution of an active NADPH oxidase complex suggests type III secretion system to be a new approach for cellular therapy.

B-Lymphocytes↗
PubMed2000

Determination of the enantiomers of 3-tert.-butylamino-1,2-propanediol by high-performance liquid chromatography coupled to evaporative light scattering detection.

A method for the separation and quantitation of the enantiomers of 3-tert.-butylamino-1,2-propanediol by high-performance liquid chromatography and evaporative light scattering detection has been developed. Separation of the enantiomers was performed in normal-phase liquid chromatography on a Chiralpak AS chiral stationary phase. The influence of the gas nature, gas pressure and temperature of the drift tube of the evaporative light scattering detector on the detection sensitivity was investigated. The method was validated in terms of linearity, limit of quantitation, accuracy and precision. The enantiomeric excess of (S)-3-tert.-butylamino-1,2-propanediol, used for the industrial synthesis of (S)-timolol, was measured from 0 to 94%.

Chromatography, High Pressure Liquid↗
PubMed2000

Postoperative brachytherapy alone for T1-2 N0 squamous cell carcinomas of the oral tongue and floor of mouth with close or positive margins.

PURPOSE: To evaluate the efficacy of postoperative brachytherapy alone (brachy) for Stage T1-2 squamous cell carcinomas (SCC) of the floor of mouth (FM) and the oral tongue (OT) with close or positive margins. METHODS AND MATERIALS: Between 1979 and 1993, 36 patients with T1-2 N0 (24 T1, 12 T2) OT (19), and FOM (17) SCC with close or positive margins following surgery underwent postoperative brachy. Mean patient age was 56 years (range 37-81) and sex ratio was 3.5:1 male:female. Mean surgery to brachy interval was 36 days (range 16-68). The technique used was interstitial Iridium-192 ((192)Ir) brachytherapy with plastic tubes and manual afterloading. Mean total dose was 60 Gy (range 50-67.4) at a mean dose rate of 0.64 Gy/h (range 0.32-0.94). Mean patient follow-up was 80 months. RESULTS: The 5-year actuarial overall and cause-specific survivals of the entire group were 75% and 85%, respectively. The local control was 88.5% at 2 years, with a plateau apparent after 23 months. Of the 4 local relapses, 2 were salvaged with surgery and external beam radiotherapy (EBR). No tumor or treatment factors, including tumor size, margin status, disease site, or radiation dose, were correlated with local control. The 2 head and neck second primaries underwent curative treatment on nonirradiated tissue. One patient developed a grade 3 sequelae (bone and soft tissue necrosis). Grade 2-3 chronic sequelae were seen in 7 of 17 and 3 of 19 FOM and OT tumors, respectively (p = 0.09). CONCLUSION: Postoperative brachy is a promising approach in T1-2 N0 OT and FOM SCC with close or positive margins. This approach is associated with high rate of locoregional control and low risk of chronic sequelae, obviates major surgery, avoids potential sequelae of EBR (xerostomia, dysgueusia, fibrosis), and avoids treatment of second head and neck primary on nonirradiated tissues.

Adult↗
PubMed2000

Enantiomeric separation of clenbuterol by transient isotachophoresis-capillary zone electrophoresis-UV detection new optimization technique for transient isotachophoresis.

A method for the in-line preconcentration and enantioseparation of clenbuterol by transient isotachophoresis-capillary zone electrophoresis-UV absorbance detection (transient ITP-CZE-UV) has been developed. It implies the use of dimethyl-beta-cyclodextrin as chiral selector and the application of a hydrodynamic counterflow during the ITP step. ITP is used to focus the sample constituents prior to CE whereas a counterpressure counterbalances the electrophoretic migration of the compounds. The sample is then focused and kept stationary in the proximity of the capillary inlet before CZE separation, leading to an extended-volume ITP-CZE system. A new strategy for the fast optimization of the counterpressure has been developed which implies the measurement of the hydrodynamic and electrophoretic velocities of the analyte during ITP. The in-line preconcentration and enantioseparation of clenbuterol selected as model compound was optimized using this method. Salbutamol was chosen as internal reference in order to check the reproducibility of the method. A 173-nl volume of aqueous ample solution was injected which implies an improvement of the injection volume of about 16 and a resolution of 4.8 was obtained for the clenbuterol enantiomers. A concentration detection limit of 10(-6) mol/l was readily achieved for clenbuterol and salbutamol using only 3 min ITP preconcentration in in-line counterflow transient ITP-CZE-UV. Thanks to its fast optimization, the method is applicable to any enantioseparation by means of only five very short preliminary measurements.

Clenbuterol↗
PubMed2000

Comparative evaluation of four detectors in the high-performance liquid chromatographic analysis of chiral nonaromatic alcohols.

A comparative evaluation of ultraviolet, polarimetric, refractive index, and evaporative light-scattering detection coupled with high-performance liquid chromatography has been developed for the separation and quantitation of the enantiomers of chiral nonaromatic alcohols, some of which are intermediates in the synthesis of chiral drugs. (R,S)-3-tert-butylamino-1,2-propanediol; (R,S)-glycidol; and (R,S)-1-(4-morpholino)-2-octanol are selected as model compounds in order to compare the detection sensitivity and the linearity of the response with the four detectors. Separation of the enantiomers is performed using chiral stationary phases in normal-phase liquid chromatography. A one-day validation is achieved for (S)-3-tert-butylamino-1,2-propanediol with each detector, and limits of quantitation are determined for the three compounds. Advantages and limitations of the four detectors are discussed.

Alcohols↗
PubMed2000

Pseudomonas aeruginosa cystic fibrosis isolates induce rapid, type III secretion-dependent, but ExoU-independent, oncosis of macrophages and polymorphonuclear neutrophils.

Pseudomonas aeruginosa, an opportunistic pathogen responsible most notably for severe infections in cystic fibrosis (CF) patients, utilizes the type III secretion system for eukaryotic cell intoxication. The CF clinical isolate CHA shows toxicity towards human polymorphonuclear neutrophils (PMNs) which is dependent on the type III secretion system but independent of the cytotoxin ExoU. In the present study, the cytotoxicity of this strain toward human and murine macrophages was demonstrated. In low-multiplicity infections (multiplicity of infection, 10), approximately 40% of the cells die within 60 min. Analysis of CHA-infected cells by transmission electron microscopy, DNA fragmentation assay, and Hoechst staining revealed the hallmarks of oncosis: cellular and nuclear swelling, disintegration of the plasma membrane, and absence of DNA fragmentation. A panel of 29 P. aeruginosa CF isolates was screened for type III system genotype, protein secretion profile, and cytotoxicity toward PMNs and macrophages. This study showed that six CF isolates were able to induce rapid ExoU-independent oncosis on phagocyte cells.

ADP Ribose Transferases↗
PubMed2000

[Prosthesis fitting after maxillectomy: an indispensable factor in acceptance and rehabilitation].

Surgical resection is often required for maxillary cancer, producing a communication between the oral cavity and the nose or paranasal sinuses. After maxillectomy, patients experience major dysfunction in speech and swallowing which have a very negative psychological effect. These problems can be overcome with an immediate prosthesis but to be fully successful, coordinated work is required between the surgeon and the maxillofacial prosthodontist before, during and after surgery. Ten days after surgery, an interim obturator is made with soft lining materials. This prosthesis will evolve as scar tissue forms, preparing space for the definitive obturator which will restore good quality of life for maxillectomy patients.

Dental Prosthesis Design↗
PubMed1999

Cell death of human polymorphonuclear neutrophils induced by a Pseudomonas aeruginosa cystic fibrosis isolate requires a functional type III secretion system.

With a coincubation model incorporating Pseudomonas aeruginosa and human polymorphonuclear neutrophils (PMNs), a cystic fibrosis (CF) P. aeruginosa isolate has been shown to resist the bactericidal action of PMNs and to induce their cellular death. An isogenic mutant of this CF isolate in which the type III secretion system was rendered nonfunctional was unable to induce cellular death of PMNs.

Blood Bactericidal Activity↗
PubMed1999

Vascular endothelial growth factor gene and protein: strong expression in thyroiditis and thyroid carcinoma.

Angiogenesis is implicated in several pathological conditions, such as inflammation and tumor growth. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a potent stimulator of endothelial cell proliferation in vitro and in vivo. The present work aimed to compare VEGF expression in human normal thyroid glands, thyroiditis tissue and thyroid carcinomas using immunohistochemistry and in situ hybridization (ISH). Both chronic lymphocytic thyroiditis and differentiated thyroid carcinomas were found to strongly express VEGF mRNA and encode larger amounts of VEGF than normal thyroid tissue as attested by a VEGF immunostaining score. In addition, tumor samples from patients with metastases showed a higher immunostaining score than their non-metastatic counterparts (P<0.05). Carcinomas with the greatest contents of VEGF mRNA and VEGF protein had the most intense mitogenic activity. Special focus on endothelial cells showed intense mitogenic activity in neoplastic tissues in contrast to the total quiescence of endothelial cells in non-tumoral tissues. An intense VEGF production by differentiated thyroid carcinoma, attested either by a higher immunostaining score or a strong VEGF mRNA expression using ISH, could be a promising marker of tumor aggressiveness and may also be useful as a predictor of metastatic potential.

Adult↗
PubMed1999

Automated sample preparation techniques for the determination of drug enantiomers in biological fluids using liquid chromatography with chiral stationary phases.

The determination of drug enantiomers has become of prime importance in the field of pharmaceutical and biomedical analysis. Liquid chromatography (LC) is one of the most frequently used techniques for achieving the separation and quantitation of the enantiomers of drug compounds. In the bioanalytical field, the integrated systems present an interesting alternative to time-consuming sample preparation techniques such as liquid-liquid extraction. Solid phase extraction (SPE) on disposable cartridges, dialysis or column switching are sample preparation techniques that can be fully automated and applied to enantioselective analysis in biological fluids. The selection of the most appropriate LC mode and chiral stationary phase for enantioseparations in bioanalysis is discussed and some aspects of these automated sample preparation procedures are compared, such as selectivity, detectability, elution of the analytes from the extraction sorbent, sample volume and analyte stability.

Buffers↗
PubMed1997

Structural study of the response regulator HupR from Rhodobacter capsulatus. Electron microscopy of two-dimensional crystals on a nickel-chelating lipid.

Two-dimensional crystals of the histidine-tagged-HupR protein, a transcriptional regulator from the photosynthetic bacterium Rhodobacter capsulatus, were obtained upon specific interaction with a Ni2+-chelated lipid monolayer. HupR is a response regulator of the NtrC family; it activates the transcription of the structural genes, hupSLC, of the [NiFe]hydrogenase. The lipid (Ni-NTA-DOGA) uses the metal chelator nitrilotriacetic group as the hydrophilic headgroup and contains unsaturated oleyl tails to provide the fluidity necessary for two-dimensional protein crystallization. A projection map of the full-length protein at 18 A resolution was generated by analysing electron microscopy micrographs of negatively stained crystals. The HupR protein appeared to be dimeric and revealed a characteristic "propeller-like" motif. Each monomer forms an L-shaped structure.

Bacterial Proteins↗
PubMed1997

Cervical lymph node metastasis from an unknown primary: is a tonsillectomy necessary?

PURPOSE: The detection of an infraclinical primary by tonsillectomy in case of cervical lymph node of an epidermoid carcinoma with unknown primary after a radical neck dissection, allows avoiding irradiation of the normal larynx. The aim of this study is to quantify the rate of tonsil primary to justify this procedure. METHODS AND MATERIALS: From 1969 to 1992, 87 patients had a tonsillectomy as part of the workup for cervical nodal metastasis of an epidermoid carcinoma with unknown primary. The mean age was 57 years (range: 39-75 years) and the sex ratio was 8.6. Sixty-seven patients had a single cervical adenopathy (17 N1, 30 N2a, 5 N3, 15 Nx), and 20 patients multiple cervical adenopathies (17 N2b, 3 N2c). The treatments included always an irradiation to the node areas (50 Gy), and to the pharyngolarynx in case of normal tonsil (50 Gy), or to the tonsil if it was the primary (50 Gy with a brachytherapy boost of 20-25 Gy). In this last case, the larynx could be protected. RESULTS: Tonsillectomy never induced specific complication. Out of 87 patients, 26% had a tonsil primary. There was not specific histological differentiation in this group. In the 67 patients with a single cervical adenopathy, 31% had a tonsil primary (6 N1, 7 N2, 1 N3, 7 Nx). It was a subdigastric adenopathy in 38%, a submandibular in 28% and a midjugulocarotidian in 23%. Among the 17 patients N2b, none had a tonsil primary. In the three patients N2c, two presented a tonsil carcinoma (two subdigastric nodes). CONCLUSION: Tonsillectomy allows avoiding irradiation of normal larynx in 26% of patients who have a cervical lymph node with unknown primary. It should be performed in case of a single node of the subdigastric, midjugulocarotidian or submandibular area or bilateral subdigastric adenopathies.

Adult↗
PubMed1997

Enantioselective determination of oxprenolol in human plasma using dialysis coupled on-line to reversed-phase chiral liquid chromatography.

A fully automated method for the determination of the enantiomers of oxprenolol in human plasma was developed, involving dialysis through a cellulose acetate membrane, clean-up and enrichment of the dialysate on a short precolumn and subsequent chiral liquid chromatographic (LC) analysis. All sample handling operations were executed automatically by a sample processor equipped with a robotic arm (ASTED system). The trace enrichment column (TEC) was packed with octadecylsilica. After conditioning of the TEC with the LC mobile phase and pH 3.0 acetate buffer. After the enrichment step, the analyte was transferred by the LC mobile phase to the analytical column by means of a switching valve. The influence of different parameters of the dialysis process on the recovery of oxprenolol was first investigated using achiral LC conditions. The volume as well as the aspirating and dispensing flow rates of the acceptor solution were the main parameters studied. Oxprenolol was separated on a C18 stationary phase used for the enantioseparation of oxprenolol was a Chiralcel OD-R column which contained cellulose tris (3,5-dimethylphenylcarbamate) coated on silica as chiral selector. The corresponding mobile phase consisted of a mixture of pH 6.0 phosphate buffer containing NaClO4 at 0.45 M concentration and acetonitrile (70:30 v/v). UV detection was performed at 273 nm. The method developed was validated. Recoveries for each enantiomer of oxprenolol were about 80%. The method was found to be linear in the 50-2500 ng ml-1 concentration range (r2 = 0.999 for both enantiomers) and good results with respect to intra- and inter-day reproducibility as well as accuracy were obtained.

Adrenergic beta-Antagonists↗
PubMed1997

Cloning, sequence and mutagenesis of the structural gene of Pseudomonas aeruginosa CysB, which can activate algD transcription.

Pseudomonas aeruginosa strains infecting patients with cystic fibrosis (CF) acquire a mucoid phenotype due to overproduction of alginate. The key enzyme in alginate synthesis is AlgD, whose promoter is transcriptionally active in mucoid strains and under the control of several trans-acting factors, including the integration host factor (IHF). The algD promoter (palgD) contains two IHF-binding sites (ihf1 and ihf2). Study of IHF binding to ihf2 of palgD, by electrophoretic mobility-shift assays, led to the discovery of a protein of 36 kDa (p36) able to bind downstream from ihf2, to the 3' region of palgD. The gene encoding p36 was isolated from the mucoid strain CHA of P. aeruginosa and sequenced. It can encode a 324-amino-acid protein, which shares a high degree of sequence identity (63%) with CysB from Escherichia coli and from Salmonella typhimurium, a transcriptional factor of the LysR superfamily. Furthermore, both p36 and S. typhimurium CysB bind the same site of palgD; p36 was therefore termed CysB and its structural gene was called cysB. Next to cysB, on the opposite DNA strand, cysH was capable of encoding a protein sharing 26% identity with CysH (PAPS reductase) of E. coli and an even greater identity (54%) with the nucleotide-deduced protein from Arabidopsis. A CysB-deficient mutant of CHA, constructed by insertional inactivation of cysB, was a cysteine auxotroph and was unable to form a specific complex with palgD in vitro. Activity of palgD in the cysB mutant, in CHA and in the non-mucoid strain PAO was assessed by the use of a transcriptional algD-xylE fusion. Cells of PAO and of the cysB mutant grown in minimal media in the presence of 0.3 M NaCl exhibited a palgD activity, which was 10% or less that of the mucoid strain CHA. Thus, P. aeruginosa CysB can act as an activator of algD expression.

Bacterial Proteins↗
PubMed1997

The Rhodobacter capsulatus hupSLC promoter: identification of cis-regulatory elements and of trans-activating factors involved in H2 activation of hupSLC transcription.

The [NiFe]hydrogenase of the photosynthetic bacterium Rhodobacter capsulatus is encoded by the structural hupSLC operon, the expression of which is induced by H2. H2 activation was no longer observable in chromosomal hupR mutants, an indication that HupR is implicated directly in the activation by H2 of hupS gene expression. The transcriptional start site of the hupS promoter, determined by primer extension mapping, was located 55 nucleotides upstream from the translational start codon of the hupS gene. Regulatory sequences were identified by serial 5' deletions of the 300bp hupS promoter-regulatory region (phupS) and phupS-lacZ translational fusions. Cis-regulatory sequences capable of interacting with two transcription factors, IHF and HupR, a response regulator of the NtrC subfamily, were studied by electrophoretic mobility shift assays (EMSAs). The R. capsulatus IHF and HupR proteins were overexpressed in Escherichia coli and purified by affinity chromatography. IHF binds to a site, 5'-TCACACACCATTG, centred at -87 nt from the transcription start site. The HupR protein binds to one site within the -162 to -152 nt region, which contains the palindromic sequence 5'-TTG-R5-CAA. By the use of 5' deletions and site-directed mutagenesis of the -162/-152 region, this palindrome was shown to be required for in vivo hupS transcriptional activation by H2.

Artificial Gene Fusion↗
PubMed1997

[Anterior frontal laryngectomy without epiglottoplasty or modified Tucker's technique. Proposal for a surgical simplification].

By replacing epiglottic reconstruction with a muscular translation, we attempted to simplify the near total laryngectomy with epiglottic reconstruction and improve swallowing disorders. Ten operated patients were followed up for at least 9 to 22 months. We obtained 9 good results and 1 failure. The long terms results have to be evaluated to assess risk of laryngeal stenosis.

Aged↗