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Biomedical subjects

B Toussaint

Publications and source records attributed to B Toussaint.

At least 19 recordsLinked to original sources
PubMed2006

Towards the certification of the purity of calibrant reference materials for thyroid hormones: a chicken and egg dilemma.

The certification of the purity of CRMs intended for calibration, where no other certified material already exists for comparison, raises principle questions on how to determine the purity of a "first" calibrant in the calibration hierarchy. We developed and certified two calibration CRMs for their purity in thyroid hormones taking into consideration inorganic residues, residual solvents and organic impurities detectable by HPLC-UV and HPLC-MS. IRMM-468 was certified for a thyroxine (T(4)) mass fraction of 98.6+/-0.7% and IRMM-469 was certified for a 3,3',5-triiodothyronine (T(3)) mass fraction of 97.1+/-0.7%. The approach we used aims to determine the purity of these two CRMs to the best of our knowledge and taking all scientific aspects properly into account for the estimation of an uncertainty related to the stated purity.

Calibration↗
PubMed2006

Small cell neuroendocrine carcinoma of the nasal cavity and paranasal sinuses.

INTRODUCTION: Small cell neuroendocrine carcinoma (SNEC) of the sinonasal tract is a rare disease. OBJECTIVE: Report a descriptive study of a relatively large cohort of SNEC of the nasal cavity and paranasal sinuses. METHOD: The medical records of 21 patients presenting with nasal and paranasal SNEC to various French hospitals, from 1989 to 2003, were analysed to determine the clinical features and current treatment of the disease. RESULTS: Patient data were obtained from eight French hospitals. Twelve of the patients were male and nine were female, with a mean age at presentation of 55 years (range: 27 to 79 years). Patients' staging for nasal cavity malignancy was: T1, four; T2, three; T3, one; T4, 13; N0, 18; N2, three; M0, 20; and M1, one. None of the patients suffered from SNEC of the sinonasal tract with ectopic hormone production. Immunohistochemistry proved useful for diagnosis in 20 cases. Twelve cases were positive for cytokeratin, 14 for chromogranin, eight for neuron-specific enolase and 11 for neuron-specific synaptophysin. One patient had an adenocarcinoma and an inverted papilloma associated with neuroendocrine carcinoma. Patients underwent surgery (11 cases), radiotherapy (14 cases) and chemotherapy (12 cases). Recurrence occurred in 10 cases. Five patients had visceral metastases or cervical lymph node involvement. Nine of the patients died within four years of onset of the disease. CONCLUSION: Small cell neuroendocrine carcinoma of the sinonasal tract is an uncommon neoplasm with aggressive clinical behaviour. Recurrence is frequent and the prognosis is poor. However, the current treatment of these neuroendocrine neoplasms varies widely.

Adult↗
PubMed2006

PsrA is a positive transcriptional regulator of the type III secretion system in Pseudomonas aeruginosa.

The type III secretion system (TTSS) of Pseudomonas aeruginosa is induced in vivo upon contact with eukaryotic cells and in vitro by calcium depletion in culture medium. We have observed a previously identified protein, PsrA, necessary for full activation of TTSS gene expression in P. aeruginosa. Electrophoretic mobility shift assays showed that recombinant PsrA could bind to the exsCEBA promoter region. A mutant with a deletion in the psrA gene was constructed. Using transcriptional fusions, we demonstrated that PsrA is required for the full activation of transcription of the TTSS regulatory operon exsCEBA and effector exoS, although the deletion mutant still responded to calcium depletion, to serum, and to host cell contact. The psrA mutant showed a marked decrease in the secretion of the type III effectors and weak resistance to phagocyte-like PLB-985 cells. The defect in TTSS transcription and secretion in the psrA mutant could be complemented by expression in trans of psrA. PsrA was previously identified as a transcriptional activator of RpoS, a central regulator during stationary phase. We confirmed with our strain that RpoS has a negative effect on TTSS gene expression. Taken altogether, these results suggest that PsrA is a newly identified activator that is involved in the expression of the TTSS by enhancing the exsCEBA transcriptional level.

ADP Ribose Transferases↗
PubMed2005

High level production of secreted proteins: example of the human tissue inhibitor of metalloproteinases 1.

The major difficulty for high-throughput screening of therapeutic protein candidates in experimental animal models of pathologies or for structural studies is their fast and efficient production. The tissue inhibitors of metalloproteinases (TIMPs) considered to play a role in many physiological and pathological processes, such as arthritis or cancer, by inhibiting matrix metalloproteinases or acting as signalling molecules, have always been produced with huge difficulties. We hereby propose a new method to overproduce human recombinant TIMP-1 by transient expression in HEK293E cells, followed by a one-step chromatography purification, yielding in only 2 weeks, dozens of milligrams of pure, stable, glycosylated and active protein for in vitro and in vivo studies. This easy to set up, rapid, and efficient method could be applied for any naturally secreted mammalian protein.

Cell Line↗
PubMed2005

Determination of (fluoro)quinolone antibiotic residues in pig kidney using liquid chromatography-tandem mass spectrometry. Part II: intercomparison exercise.

A recently in-house validated method for the liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of eleven (fluoro)quinolone antibiotics (FQs) in pig kidney has been fully validated through an intercomparison exercise. This ring trial involved eight European laboratories and was based on the Commission Decision 2002/657/CE for validation of method and on the IUPAC protocol for method-performances studies. The laboratories data were submitted to a one-way analysis of variance. Satisfactory results were obtained for each FQ with regards to within- and between-laboratory reproducibility and accuracy. The method was validated for the simultaneous qualitative and quantitative determination of the eleven FQs in pig kidney around their maximum residue limit (MRL) as defined in the European Council Regulation 2377/90/EEC.

Animals↗
PubMed2005

Determination of (fluoro)quinolone antibiotic residues in pig kidney using liquid chromatography-tandem mass spectrometry. I. Laboratory-validated method.

A new LC-MS/MS method has been developed for the multiresidue determination of 11 (fluoro)quinolone antibiotics (FQs), including acidic and amphoteric species, around their maximum residue level (MRL) in pig kidney. The procedure involves a common sample preparation by solid-phase extraction on disposable extraction cartridges followed by a fast reversed-phase liquid chromatography-tandem mass spectrometry analysis. The method was validated according to the Commission Decision 2002/657/CE. The accuracy of the method was satisfactory with recoveries included in the interval 80-100%. The precision results showed mean repeatability and reproducibility coefficients of 7.4% and 11.8%, respectively. Limits of quantification much lower than the MRLs could be obtained.

Animals↗
PubMed2005

[Propositions for the selection and the delineation of peritumoral microscopic disease volumes in oral cavity and oropharyngeal cancers (lymph nodes excluded)].

This article reviews the concept of selectivity in peritumoral microscopic disease to be included in the Clinical Target Volume (CTV) for elective treatment for oral cavity and oropharyngeal squamous cell carcinoma, using the local tumoral spread. The objective of the present article is to present a procedure for the delineation of the target volumes, required for an appropriate application of 3-DCRT and IMRT for head and neck cancers. These propositions are for the delineation of microscopic peritumoral target volumes when external beam irradiation is required. CTVs are illustrated on CT sections.

Carcinoma, Squamous Cell↗
PubMed2005

[Arthroscopic repair of full-thickness cuff tears: a multicentric retrospective study of 576 cases with anatomical assessment].

PURPOSE OF THE STUDY: Totally arthroscopic repair of rotator cuff tears is now common practice. The techniques used were evaluated by a retrospective multicentric analysis conducted by the French Society of Arthroscopy. MATERIAL AND METHODS: The series was limited to arthroscopic repair of full thickness tears of the supraspinatus or infraspinatus evaluated using the Constant score and arthro-MRI or arthroscan performed with at least one year follow-up. Data were processed with SPSS 10. The series included 576 patients who underwent surgery between January 2001 and June 2003. Mean patient age was 57.7 years; 52% were men and 60% were manual laborers. The mean preoperative Constant score was 46.4 +/- 13.4/100. The tear was limited to the supraspinatus in 69% of shoulders, with extension to the upper third of the infraspinatus in 23.5% and the entire infraspinatus in 7.5%. The supraspinatus tear was distal in 41.7% of shoulders, intermediary in 44% and retracted in 14.3%. Fatty degeneration of the supraspinatus was noted grade 0 in 60%, 1 in 27%, 2 in 11% and 3 in 2%. Arthroscopic repair was performed in all cases, with locoregional anesthesia in 60.9%. Bioresorbable implants were used in 33% and metallic implants in 62.1%. Acromioplasty was performed in 92.7% and capsulotomy in 14.9%. RESULTS: On average, the subjective outcome was scored 8.89/10. The Constant score improved from 46.3 +/- 13.4 to 82.7 +/- 10.3 with 62% having a strictly pain free shoulder. Muscle force improved from 5.8 +/- 3.7 to 13.6 +/- 5.4. Outcome was excellent in 94% of shoulders at 18.5 months mean follow-up. The complication rate in this series was 6.2% with 3.1% prolonged stiffness, 2.7% reflex dystrophy, 0.2% infection, and 0.2% anchor migration. The cuff was considered normal in 55.7% of shoulders with an intratendon addition image in 19%, i.e. 74.7% of non-ruptured cuffs. Minimal loss of integrity was noted in 9.5% and was marked in 15.7%, i.e. 25.2% iterative tears.ANATOMOCLINICAL CORRELATIONS: The Constant score was strongly correlated with rotator cuff integrity (p<0001). This correlation was also found for force (p<0001), motion (0.01) and activity (0.04), but not for pain. The clinical outcome was correlated with extension, retraction, intrasubstance tear, and fatty degeneration of the lesion preoperatively. Anatomic results were statistically less favorable for tears which were older, extensive, retracted or associated with fatty degeneration. Age was correlated with extent of the initial tear and also with less favorable anatomic and clinical outcome. Occupational accidents were correlated with less favorable clinical outcome. CONCLUSION: Functional improvement after healing is a strong argument for repair. Arthroscopy has the advantage of combining a low complication rate with good clinical and anatomic results. Age is correlated with functional outcome and healing, but is not a contraindication.

English Abstract↗
PubMed2005

Alveolar response to Pseudomonas aeruginosa: role of the type III secretion system.

The type III secretion system (TTSS) is a specialized cytotoxin-translocating apparatus of gram-negative bacteria which is involved in lung injury, septic shock, and a poor patient outcome. Recent studies have attributed these effects mainly to the ExoU effector protein. However, few studies have focused on the ExoU-independent pathogenicity of the TTSS. For the present study, we compared the pathogenicities of two strains of Pseudomonas aeruginosa in a murine model of acute lung injury. We compared the CHA strain, which has a functional TTSS producing ExoS and ExoT but not ExoU, to an isogenic mutant with an inactivated exsA gene, CHA-D1, which does not express the TTSS at all. Rats challenged with CHA had significantly increased lung injury, as assessed by the wet/dry weight ratio for the lungs and the protein level in bronchoalveolar lavage fluid (BALF) at 12 h, compared to those challenged with CHA-D1. Consistent with these findings, the CHA strain was associated with increased in vitro cytotoxicity on A549 cells, as assessed by the release of lactate dehydrogenase. CHA was also associated at 12 h with a major decrease in polymorphonuclear neutrophils in BALF, with a proinflammatory response, as assessed by the amounts of tumor necrosis factor alpha and interleukin-1beta, and with decreased bacterial clearance from the lungs, ultimately leading to an increased mortality rate. These results demonstrate that the TTSS has a major role in P. aeruginosa pathogenicity independent of the role of ExoU. This report underscores the crucial roles of ExoS and ExoT or other TTSS-related virulence factors in addition to ExoU.

Animals↗
PubMed2002

Validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of 11 (fluoro)quinolone antibiotics in swine kidney.

A LC-MS-MS method has been validated for the simultaneous quantification of 11 (fluoro)quinolone antibiotics at the maximum residue level (MRL) in swine kidney. The studied compounds were danofloxacine, cinoxacine, ciprofloxacine, noxacine, enrofloxacine, flumequine, marbofloxacine, nalidixic acid, norfloxacine, ofloxacine and oxolinic acid. The method involves solid-phase extraction of these compounds followed by LC-MS-MS analysis using an electrospray ionisation interface. Limits of quantification < or = 50 microg/kg could be obtained in swine kidney, much lower than every MRL. The validation is discussed. This work was carried out in order to support the European Union policy on consumer health

Animals↗
PubMed2001

On-line coupling of partial filling-capillary zone electrophoresis with mass spectrometry for the separation of clenbuterol enantiomers.

The on-line coupling of capillary zone electrophoresis with mass spectrometry (CZE-MS) for the separation of enantiomers is hampered by the presence of nonvolatile chiral selectors such as cyclodextrins in the separation buffer. This problem can be overcome by use of the partial filling technique where only a part of the capillary is filled with the separation buffer containing chiral selectors. Since the electroosmotic flow is almost completely suppressed at acidic pH, that dimethyl-beta-cyclodextrin is neutral, no free cyclodextrin would reach the MS detector when using a partially filled capillary. By this method, clenbuterol enantiomers were successfully resolved and separated from salbutamol (internal standard) in aqueous solution and in plasma samples. A solid-phase extraction (SPE) was used for the preparation of plasma samples before analysis.

Clenbuterol↗
PubMed2001

Variability in urinary excretion of bone resorption markers: limitations of a single determination in clinical practice.

In this study we assessed the within and between-subject variability of the concentrations of two urinary markers, free deoxypyridinoline (DPD) and C telopeptide (CTX-I), in healthy patients with the aim of setting reliable thresholds to enable physicians to take decisions about individual patients with confidence.Between-subject variability for the women was 25.4% for DPD and 38.2% for CTX-I, and for the men was 12.9% for DPD and 23.8% for CTX-I. The coefficients of variation were similar for daily, weekly and monthly determinations, giving means of 13.8 and 28.1% for DPD and CTX-I respectively. Critical difference (CD) was lower for DPD than for CTX-I (about 44 and 80% respectively). The number of samples required to determine the true mean with a CD at the 5% level was 29 for DPD and more than 113 for CTX-I.DPD was the least biologically variable. One determination was not sufficient to determine bone resorption status and a 44% decrease in DPD levels and an 80% decrease in CTX-I levels were required to demonstrate the efficacy of antiresorptive therapy in individual patients.

Adult↗
PubMed2001

Expression of ExsA in trans confers type III secretion system-dependent cytotoxicity on noncytotoxic Pseudomonas aeruginosa cystic fibrosis isolates.

Twelve Pseudomonas aeruginosa cystic fibrosis isolates that are not able to exert a type III secretion system (TTSS)-dependent cytotoxicity towards phagocytes have been further studied. The strains, although possessing TTSS genes and exsA, which encodes a positive regulator of the TTSS regulon, showed no transcriptional activation of the exsCBA regulatory operon. The expression of exsA in trans restored the in vitro secretion of TTSS proteins and ex vivo cytotoxicity.

Bacterial Proteins↗
PubMed2001

Increased expression of the vascular endothelial growth factor is a pejorative prognosis marker in papillary thyroid carcinoma.

Vascular endothelial growth factor (VEGF) is a potent stimulator of endothelial cell proliferation. It has been implicated in tumor growth of human thyroid carcinomas. Using the VEGF immunohistochemistry staining score, we correlated the level of VEGF expression with the metastatic spread of 19 cases of thyroid papillary carcinoma. The VEGF immunostaining score, ranging from 0-9, was determined as the multiplication of a percentage of labeled thyrocytes score (0, no labeling; 1, <30%; 2, 31--60%; 3, >61% of labeled thyrocytes) and an intensity score (0, no staining; 1, weak; 2, mild; 3, strong staining). The mean score +/- SD was 5.74 +/- 2.59 for all carcinomas. The mean score for metastatic papillary carcinoma was 8.25 +/- 1.13 vs. 3.91 +/- 1.5 for nonmetastatic papillary cancers (P < 0.001). By discriminant analysis, we found a threshold value of 6.0, with a sensitivity of 100% and a specificity of 87.5%. There were no statistical differences between metastatic and nonmetastatic carcinomas when age, tumor size, or thyroglobulin levels were considered. The VEGF immunostaining score seems to be a helpful marker for metastasis spread in differentiated thyroid cancers. An increased production of VEGF could assess an aggressive disease and be the hallmark of a trend to produce metastasis. We propose the VEGF immunostaining score as a marker for the prognosis in differentiated thyroid cancers. A value of 6 or more, should be considered as at high risk for metastasis threat, prompting the physician to institute a tight follow up of the patient.

Adolescent↗
PubMed2001

[Management of mucositis following radiotherapy for head and neck cancers].

Acute mucositis is common after radiotherapy for head and neck cancers. During the past 3 decades, there was a gradual evolution in the treatment modalities for locally advanced carcinomas (concomitant radio-chemotherapy, accelerated radiotherapy). These new strategies are accompanied by an increase in early mucosal reactions. At the present time, there is no widely accepted prophylaxis or effective treatment. Many traditional remedies or new agents seem ineffective (Sucralfate, Chlorhexidine, GM-CSF, Silver nitrate, Prostaglandin, anti-oxidants, Benzydamine hydrochloride), while others seem promising (Povidone-iodine, nonabsorbable antibiotic lozenges and antifungals, local GM-CSF, Glutamide, Low-energy laser, corticosteroïds). Radioprotectors are controversial and should be only used in experimental protocols and not in routine practice. However, some recommendations can be proposed: general prevention and global care before cancer therapy should be systematic (oral hygiene, dental and periodontal treatment, advice to avoid the use of tobacco and alcohol); frequent oral rinsing with a bland mouthwash (Povidone-iodine or others) should be used at the start of treatment because there are significant modifications of the oral microflora increased by a disturbed salivary flow; these mouthwashes could be associated with nonabsorbable antibiotic lozenges or antifungal topicals (bicarbonates, Amphotéricine B); Systematic percutaneous fluoroscopic gastrostomy should be decided before any aggressive treatments (concomitant radio-chemotherapy, accelerated radiotherapy); pain should be controlled; finally, the radiation technique should be optimized (mucosal-sparing block, conformal radiotherapy and intensity-modulated radiation therapy).

Acute Disease↗
PubMed2000

Determination of the enantiomers of 3-tert.-butylamino-1,2-propanediol by high-performance liquid chromatography using mass spectrometric detection.

The chiral synthesis of beta-blockers such as (S)-timolol requires a sensitive analytical method for the enantioseparation of its intermediate, 3-tert.-butylamino-1,2-propanediol, in the ng/ml range. The method developed is based on on-line normal-phase LC-MS-MS using a chiral stationary phase and an atmospheric pressure chemical ionization (APCI) interface. The MS detection of 3-tert.-butylamino-1,2-propanediol was first optimized with a pneumatically-assisted electrospray interface (ionspray). The APCI interface was then selected for LC-MS-MS because of the incompatibility of electrospray with n-hexane. The method was validated for both enantiomers in the 25-500 ng/ml concentration range.

Atmospheric Pressure↗
PubMed2000

Quantitative analysis of N-acetylcysteine and its pharmacopeial impurities in a pharmaceutical formulation by liquid chromatography-UV detection-mass spectrometry.

A new method for the simultaneous determination of N-acetylcysteine and its pharmacopeial impurities, cysteine, cystine, N,N'-diacetylcystine and N,S-diacetylcysteine in an effervescent tablet has been developed. The method is based on on-line LC-UV-MS using a pneumatically-assisted electrospray interface (ionspray). The stability of the thiol moieties of the analytes was ensured by the acidic pH of the LC mobile phase. Quantitation of N-acetylcysteine was performed with UV detection to avoid ion-source overloading effect due to its higher concentration, whereas the impurities could be easily separated and quantified in MS. The method was validated in terms of stability, linearity, precision and accuracy.

Acetylcysteine↗