Biomedical subjects

O Thomas

Publications and source records attributed to O Thomas.

At least 19 recordsLinked to original sources

PubMed2006

Development and characterization of interleukin-18-loaded biodegradable microspheres.

Immunostimulation represents a promising approach designed to specifically eradicate malignant cells. Since glioma tumour cells hole up in the central nervous system (CNS) in a particularly inauspicious milieu to antitumour immune reactions we here propose a new strategy to revert the properties of this microenvironment by administering an antitumour cytokine into the CNS tumour itself. Thus, biodegradable poly(D,L-lactide-co-glycolide) (PLGA) sustained-release microspheres for stereotaxic implantation loaded with interleukin-18 (IL-18), that is known to exert antitumour activity and trigger immune cell-mediated cytotoxicity, were developed. Different tests for assessing IL-18 bioactivity were set-up and evaluated. A specific bioassay was considered as the most reliable test. The stability and integrity of IL-18 was then verified during the encapsulation process. Consequently, two procedures of IL-18 encapsulation in PLGA microparticles (W/O/W and S/O/W) were investigated. As determined by radiolabelling studies using 125I-IL-18 and a continuous flow system, the in vitro release profile of IL-18 was optimum with S/O/W method with a moderate burst effect and a subsequent progressive discharge of 16.5+/-8.4 ng/day during the next 21 days against 6.1+/-4.2 ng/day with the W/O/W method. Considering analytical testing of IL-18 together with its preserved biological activity after release from microspheres, amounts of the active cytokine obtained with S/O/W method were relevant to plan in vivo evaluation to validate the therapeutic strategy.

Absorbable Implants↗

PubMed2006

Effect of MCM09, an active site-directed inhibitor of factor Xa, on B16-BL6 melanoma lung colonies in mice.

BACKGROUND: Treatment with anticoagulant drugs has shown potential inhibitory effect on tumor invasion, although the relationship with clotting inhibition was not clear. AIM: The aim of our study was to evaluate the potential antitumor activity of MCM09, a newly developed, active site-directed, small molecule inhibitor of factor Xa (FXa) [WO0216312], and to relate the findings to anticlotting potency. METHODS: MCM09 (0.1-10 mg kg(-1)) or heparin (H; 10 mg kg(-1)) was injected intravenously (i.v.), with 5 x 10(4) B16-BL6 melanoma cells, in C57BL/6 mice. Mice were killed after 18 days, to count lung colonies. Ex vivo anticoagulant activity was measured by activated partial thromboplastin time (APTT) on mouse plasma. RESULTS AND CONCLUSIONS: MCM09, a selective inhibitor of FXa (IC-50 = 2.4 nm against human FXa), inhibited in a dose-dependent manner B16-BL6 melanoma lung colonies in mice. Mean lung metastasis number was 20.9 +/- 4.8 in controls (n = 10), 1.2 +/- 0.4 in mice treated with H, 10 mg kg(-1) i.v. (P < 0.01), 0.9 +/- 0.3, 9.2 +/- 2.2 and 15.5 +/- 2.6 in mice treated with MCM09, at 10 (P < 0.01), 1 (P < 0.05) and 0.1 mg kg(-1) i.v. (ns), respectively. MCM09 (10 mg kg(-1) i.v.) significantly prolonged APTT (57.1 +/- 10.2 s) 30 min after i.v. injection when compared with controls (25.3 +/- 1.6 s; P < 0.05). Lung colonies were 74.2-72.6% reduced by MCM09 (10 mg kg(-1)) given 60 or 120 min before cells, but not by MCM09 given 60 min thereafter, suggesting a direct cell interaction as a mechanism underlying antitumor activity.

Animals↗

PubMed2004

Associations of fitness and fatness with mortality in Russian and American men in the lipids research clinics study.

OBJECTIVE: To examine the relative size of the effects of fitness and fatness on mortality in Russian men, and to make comparison to US men. DESIGN: Prospective closed cohort. SUBJECTS: 1359 Russian men and 1716 US men aged 40-59 y at baseline (1972-1977) who were enrolled in the Lipids Research Clinics Study. MEASUREMENTS: Fitness was assessed using a treadmill test and fatness was assessed as body mass index (BMI) calculated from measured height and weight. Hazard ratios were calculated using proportional hazard models that included covariates for age, education, smoking, alcohol intake and dietary keys score. All-cause and cardiovascular disease (CVD) mortality were assessed through 1995. RESULTS: In Russian men, fitness was associated with all-cause and CVD mortality, but fatness was not. For mortality from all causes, compared to the fit-not fat, the adjusted hazard ratios were 0.87 (95% CI: 0.55, 1.37) among the fit-fat, 1.86 (95% CI: 1.31, 2.62) among the unfit-not fat and 1.68 (95% CI: 1.06, 2.68) among the unfit-fat. Among US men, the same hazard ratios were 1.40 (95% CI: 1.07, 1.83), 1.41 (95% CI: 1.12, 1.77) and 1.54 (95% CI: 1.24, 2.06), respectively. There were no statistically significant interactions between fitness and fatness in either group of men for all-cause or CVD mortality. CONCLUSION: The effects of fitness on mortality may be more robust across populations than are the effects of fatness.

Adult↗

PubMed2004

Hidden isosbestic point(s) in ultraviolet spectra.

The existence of isosbestic point(s) in a set of UV-visible spectra is rarely exploited for quantitative or qualitative information despite its interest. Indeed, the presence of isosbestic points means a quality and quantity conservation in the global composition of samples with a given relation between the concentration of absorbing compounds or mixtures of compounds. However, in some cases, for example, when a dilution occurs, no isosbestic point appears. This work shows that a simple operation, called normalization, can reveal the existence of hidden isosbestic point(s) (IP*). This paper first summarizes the required conditions for the presence of isosbestic points. Second, it demonstrates the significance of IP* revealed by normalization. An example of the exploitation of direct or hidden isosbestic points in the environmental field illustrates the interest in and application of the technique.

Journal Article↗

PubMed2004

Trends in optical monitoring.

Optical techniques are often used for the development of new monitoring systems for wastewater quality. The different techniques, light scattering, UV-IR spectrophotometry, fluorimetry and image analysis have given rise to recent instruments but are often limited for industrial applications. After the presentation of the principles, the advantages and drawbacks are discussed with respect to given applications.

Environmental Monitoring↗

PubMed2004

In situ UV monitoring of wastewater: a response to sample aging.

The phenomenon of wastewater sample aging is supposed to be treated with a low temperature autosampler. This work presents two examples of treated wastewater, the quality of which varies with the time of conservation. This evolution may pose some problems with respect to regulation compliance or process control. After the explanation of the mechanisms involved in sample aging, some recommendations are proposed in order to improve the UV off-line measurement of TSS and COD of treated wastewater.

Automation↗

PubMed2004

Using bioluminescent biosensors for hazard analysis and critical control point (HACCP) in wastewater control.

Starting from a new approach for water pollution control and wastewater treatment plant management, the hazard analysis and critical control point (HACCP) quality concept, the interest for the development of new rapid and sensitive methods such as bioluminescence-based methods is evident. After an introduction of the HACCP procedure, a bibliographic study of the bioluminescence potentiality is presented and discussed.

Bacteria↗

PubMed2003

Monitoring of phenol photodegradation by ultraviolet spectroscopy.

Advanced oxidation processes (AOPs) have been developed as an emerging technology for hazardous organic treatment in industrial wastewater. In this paper, the contribution of ultraviolet (UV) spectroscopy to follow phenol photodegradation was studied in a laboratory photochemical reactor equipped with a low pressure mercury lamp. It has been observed that a multicomponent approach is efficient for the evolution estimation of the initial product or intermediate compounds formed during the photodegradation.

Chromatography, High Pressure Liquid↗

PubMed2003

Interplay between anisotropic strain relaxation and uniaxial interface magnetic anisotropy in epitaxial Fe films on (001) GaAs.

Grazing incidence x-ray diffraction study of Fe epitaxial ultrathin films (1.5-13 nm) on GaAs (001) reveals an anisotropy of both domain shape and strain, with [110] and [1-10] as the principal directions. It is shown that the observed thickness-dependent strain anisotropy, together with a uniaxial interface term, can provide an unambiguous explanation to the usual in-plane magnetic anisotropy and its thickness dependence observed in this magnetic thin-film system.

Journal Article↗

PubMed2003

UV monitoring of sugars during wine making.

A UV/UV system for the spectrophotometric determination of sugars during wine production is described. The methodology is based on the formation of a UV-absorbing byproduct produced by the photodegradation of sugars. Under the given experimental conditions, the influence of increasing the amount of acids and alcohol is negligible. The measurement by UV/UV is compared with FTIR as reference method and validated according to the French norm AFNOR XPT 90 210.

Carbohydrates↗

PubMed2003

Determination of organic matter in grinding sludges by UV spectrophotometry.

The aim of this paper is to determinate the total organic matter content of grinding sludges by a simple and fast methodology based on a solvent extraction followed by a UV spectrophotometry analysis. Several UV spectra exploitation methods are used. The multiwavelength deconvolution procedure provides quantitative results in good accordance with those obtained by a gravimetric method, possibly underestimated and enables a separate quantification of the cuttings fluids and the lubricants in the sludges. The normalisation procedure and the search of isobestic points provide important qualitative information on the evolution and on the composition of the oils used in metal processing. Therefore, this study is a first step for the development of a tool for the characterisation of organic matter in grinding sludges.

Hydrocarbons↗

PubMed2003

Study of the impact of mechanical treatments on wastewater solids by UV spectrophotometry.

The aim of this paper is, from the perspective of improvement of Total Suspended Solids (TSS) measurement by UV spectrophotometry, to study the influence of two pretreatments on the UV responses of urban wastewater (sonication and mechanical grinding). The study of optical properties evolution the different phenomena involved and show mechanical grinding as a potential pre-treatment is prosed. Mechanical grinding is applied to samples characterised by different TSS concentration and particle size distributions in order to test its feasability. Results show the limit of the pretreatment and the difficulty of exploiting the UV response of urban wastewater for TSS characterization and estimation.

Mechanics↗

PubMed2003

[Indications for implantable automatic defibrillators: critical analysis].

The implantable automatic defibrillator (IAD), invented in 1980, has revolutionised the management of patients with malignant ventricular arrhythmias resistant to medical treatment or ablation procedures. The number of devices implanted continues to increase in the industrialised countries and, based on the results of clinical trials, the indications for IAD are now well codified and increase as new clinical studies are published. However, the absolute number of implantations in France remains low (about 1200 to 2000, about 20 per million population) for a number of reasons: cost of IAD, absence of reimbursement by the health service which has restrained the implantation to public hospitals, and information of cardiologists for whom IAD may seem to be reserved for a few exceptional cases. Several factors suggest that the number of implantations will increase in the near future. First of all, the procedures of implantation have become much more simple due mainly to technical improvements. Then, the results of recent studies have validated prophylactic implantations of these devices in primary prevention in the post-infarction period (MADIT, MUSTT, MADIT II studies) and have demonstrated the superiority of IAD over antiarrhythmic drug therapy in terms of global survival in patients with severe ventricular arrhythmias (AVID, CIDS, CASH studies).

Arrhythmias, Cardiac↗

PubMed2003

[Bidirectional ventricular tachycardias].

Bidirectional tachycardias are rare arrhythmias. Nevertheless in the sixties and seventies these arrhythmias prompted much work relating to their mechanism. Discussions about the supposed supra-ventricular origin of certain bidirectional tachycardias essentially rested on presumptive arguments based on electrocardiographic analysis. All the electrophysiological investigations which could be performed in tachycardia showed a ventricular origin. The current hypotheses concerning the electrophysiological mechanism favour non-unifocal mechanisms as well as a very diverse aetiology: an automatic focus, or the triggered activities being associated with alternating conduction, or re-entry between the left hemibranches. Although the classic context is of excess digitalis with advanced cardiopathy, readily in atrial fibrillation with a poor prognosis as a corollary, the most recent description of catecholergic ventricular tachycardias with the very characteristic appearance of bidirectional tachycardias justifies updating the understanding of these unusual tachycardias.

Electrocardiography↗

PubMed2003

Bioluminescence-based assay used for toxicity monitoring.

A new ATP bioluminescence-based method is proposed in order to examine the effect of toxic shock on microbial communities in urban wastewater treatment plant (WWTP). As the efficiency of WWTP must be improved, the occurrence and toxic effect of hazardous substances have to be evaluated (Directive 2455/2001/EC). Among bioluminescence assay with firefly luciferase is commonly used for intracellular ATP monitoring. A multienzyme systems catalysed by three enzymes (adenylate kinase, pyruvate kinase and firefly luciferase) for adenine nucleotides (AN = ATP+ ADP+ AMP) estimation is used for monitoring metabolic changes in activated sludge. The AN method provides better sensitivity than ATP quantification alone. The pool of intracellular and extracellular AN is constant during growth and the rate of intracellular AN is correlated with the microbial growth. In the present investigation, the extraction of total adenylate assay is optimized (chemical and mechanical extraction) and applied for monitoring the effect of the toxic shock (eg. Naphthalene) on indigenous biomass activity (intracellular and extracellular AN rates). In the same time, the removal of naphthalene is addressed Laboratory-scale reactors (4 L) are inoculated with urban activated sludge is under continuous-flow aeration. The reactor, containing non acclimated sludge enriched with naphthalene. The other reactor containing sterilised activated sludge is used as abiotic and volatilisation control system. In all this batch cultures, ATP and AN (intracellular and extracellular) rates and naphthalene concentrations are controlled. One of the objectives of this research is to determine a relation between the ATP/AN ratio and the biodegradation of naphthalene. Evidence is given which demonstrates that the ATP/AN parameter is a possible alternative for monitoring very rapid metabolic changes in complex microbial community such as activated sludge.

Adenine Nucleotides↗

PubMed2002

Photochemical reaction monitoring by ultra-violet spectrophotometry.

Within the framework of the monitoring of the trichloroacetylchloride (TCAC) photosynthesis, ultra-violet (UV) spectrophotometry is proposed as a simple and rapid tool allowing, in real time, the control of the process efficiency. A good correlation has been obtained between the results acquired by this alternative method and the standard gas chromatography.

Chloroacetates↗

PubMed2001

Long-term complications of total body irradiation in adults.

PURPOSE: To report long-term pulmonary, thyroid, and ocular complications in patients who had conditioning regimens including total body irradiation (TBI) before bone marrow transplantation (BMT). METHODS AND MATERIALS: Between June 1986 and December 1995, 478 patients received TBI in our institution. The present study includes 186 adult patients who had complete remission lasting one year or more after BMT. There were 108 males and 78 females. Median age was 36.5 years (range 15-60). Initial diagnoses were lymphomas (50%), acute lymphoid leukemias (16%), acute myeloid leukemias (16%), chronic myeloid leukemia (13%), aplastic anemia (3%), and myelodysplasia (2%). At the time of BMT, 43.5% of patients were in complete response and 56.5% in partial response. Treatment consisted of a single dose TBI at 10 Gy in 9% and fractionated TBI delivering 12 to 13.5 Gy in 6 fractions in 91%. From 1986 to October 1991, TBI was performed in lateral position with 9 MV energy (57% of patients) and thereafter in alternate prone and supine positions with 15 MV energy (43%). Chemical conditioning regimen was cyclophosphamide (60 mg/kg at D-4 and D-3) in 69% and CBV (cyclophosphamide 1500 mg/m(2) from D-6 to D-3, BCNU 300 mg/m(2) at D-6, VP-16 200 mg/m(2) from D-6 to D-4) in 25%. Fifty eight percent of patients received autologous and 42% allogeneic BMT. All patients had clinical, biologic, and functional examinations at one-year intervals. RESULTS: Median follow-up from BMT was 49 months (range 12-136). Late pulmonary effects were observed only in functional explorations, without clinical effect, including restrictive syndrome in 8% and alteration in the diffusing capacity of carbon monoxide in 12%. No patient showed clinical thyroid symptoms, and 10% developed biologic dysfunction: hypothyroidism (6.5%), thyroiditis (3%), and Basedow disease (0.5%). Ocular complications occurred in 29.5%, including cataract (15%), dry syndrome (13%), and keratitis (1.5%). In univariate and multivariate analysis, pulmonary complications were statistically increased by chronicle graft vs. host disease (GVHD) vs. no (p = 0.02), prone and supine vs. lateral TBI position (p = 0.02), and with 15 MV vs. 9 MV beam energy (p = 0.02). Cataract occurred less frequently with fractionated than with single-dose TBI (p = 0.000002). No differences were observed regarding age, sex, initial diagnosis, status at the time of BMT, conditioning chemotherapy regimen, and total dose of TBI. CONCLUSION: From this retrospective study it was shown that long-term complications of TBI were not symptomatic in most patients. The role of parameters of irradiation and especially position of treatment and beam energy should be emphasized and assessed with a longer follow-up.

Adolescent↗

PubMed1998

[Can sevoflurane save time in routine clincal use? A comparison with halothane in pediatric anesthesia].

UNLABELLED: The volatile agent sevoflurane enables a rapid emergence from anaesthesia. The aim of this study was to investigate the possibility of increasing turnover in pediatric anaesthetic cases by use of sevoflurane in comparison with halothane. Often short cases or day cases need rapid turnover. METHODS AND PATIENTS: The pediatric patients aged 4-14 years (ASA I) presenting for elective ophthalmic surgery were randomised to either the halothane or the sevoflurane group. Standard monitoring was applied to all patients, in addition the pEEG was used to determine comparable anaesthetic depth. Sevoflurane or halothane were titrated to a SEF 90 of 8-12 Hz. Management of the airway was done with the RLMA (reinforced laryngeal mask). All patients were under controlled ventilation. At the end of surgery and anaesthesia 3 time intervals were measured: phase I) end of anaesthetic application--start of spontaneous respiration; phase II) start of spontaneous respiration--removal of RLMA. The SEF 90 interval was also assessed. RESULTS: 18 cases were included (halo n = 8/sevo n = 10, no significant differences concerning weight, age, anaesthesia time). There is a significant advantage for the Sevoflurane group in phase II of 6.8 minutes. No differences were seen in phase I and SEF 90 interval. CONCLUSION: Sevoflurane offers the potential for shortening turnover in pediatric anaesthesia.

Adolescent↗