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Yu F, Zhuo S, Qu Y, Choudhury D, Wang Z, Iliescu C, Yu H. On chip two-photon metabolic imaging for drug toxicity testing. BIOMICROFLUIDICS 2017; 11:034108. [PMID: 28529673 PMCID: PMC5426952 DOI: 10.1063/1.4983615] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 05/03/2017] [Indexed: 05/03/2023]
Abstract
We have developed a microfluidic system suitable to be incorporated with a metabolic imaging method to monitor the drug response of cells cultured on a chip. The cells were perfusion-cultured to mimic the blood flow in vivo. Label-free optical measurements and imaging of nicotinamide adenine dinucleotide and flavin adenine dinucleotide fluorescence intensity and morphological changes were evaluated non-invasively. Drug responses calculated using redox ratio imaging were compared with the drug toxicity testing results obtained with a traditional well-plate system. We found that our method can accurately monitor the cell viability and drug response and that the IC50 value obtained from imaging analysis was sensitive and comparable with a commonly used cell viability assay: MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium) assay. Our method could serve as a fast, non-invasive, and reliable way for drug screening and toxicity testing as well as enabling real-time monitoring of in vitro cultured cells.
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Alhasan L, Qi A, Al-Abboodi A, Rezk A, Chan PP, Iliescu C, Yeo LY. Rapid Enhancement of Cellular Spheroid Assembly by Acoustically Driven Microcentrifugation. ACS Biomater Sci Eng 2016; 2:1013-1022. [DOI: 10.1021/acsbiomaterials.6b00144] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Kathuria H, Kochhar JS, Fong MHM, Hashimoto M, Iliescu C, Yu H, Kang L. Polymeric Microneedle Array Fabrication by Photolithography. J Vis Exp 2015. [PMID: 26650548 DOI: 10.3791/52914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a photomask consisting of embedded micro-lenses. Embedded micro-lenses were found to influence MN geometry (sharpness). Robust MN arrays with tip diameters ranging between 41.5 µm ± 8.4 µm and 71.6 µm ± 13.7 µm, with two different lengths (1,336 µm ± 193 µm and 957 µm ± 171 µm) were fabricated. These MN arrays may provide potential applications in delivery of low molecular and macromolecular therapeutic agents through skin.
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Iliescu C, Mărculescu C, Venkataraman S, Languille B, Yu H, Tresset G. On-chip controlled surfactant-DNA coil-globule transition by rapid solvent exchange using hydrodynamic flow focusing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13125-13136. [PMID: 25351469 DOI: 10.1021/la5035382] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper presents a microfluidic method for precise control of the size and polydispersity of surfactant-DNA nanoparticles. A mixture of surfactant and DNA dispersed in 35% ethanol is focused between two streams of pure water in a microfluidic channel. As a result, a rapid change of solvent quality takes place in the central stream, and the surfactant-bound DNA molecules undergo a fast coil-globule transition. By adjusting the concentrations of DNA and surfactant, fine-tuning of the nanoparticle size, down to a hydrodynamic diameter of 70 nm with a polydispersity index below 0.2, can be achieved with a good reproducibility.
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Poenar DP, Iliescu C, Boulaire J, Yu H. Label-free virus identification and characterization using electrochemical impedance spectroscopy. Electrophoresis 2013; 35:433-40. [DOI: 10.1002/elps.201300368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 11/09/2022]
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Iliescu C, Lamotte C, Preda C. Specific oral immunotherapy versus allergen avoidance for food allergy in children: systematic review and meta-analysis (update). Clin Transl Allergy 2013. [PMCID: PMC3723946 DOI: 10.1186/2045-7022-3-s3-p2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Tresset G, Marculescu C, Salonen A, Ni M, Iliescu C. Fine control over the size of surfactant-polyelectrolyte nanoparticles by hydrodynamic flow focusing. Anal Chem 2013; 85:5850-6. [PMID: 23713852 DOI: 10.1021/ac4006155] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Synthesis of surfactant-polyelectrolyte nanoparticles was carried out in a microfluidic device with a fine control over the size and the polydispersity. An anionic polysaccharide (sodium carboxymethylcellulose, CMC) solution was focused using a cationic surfactant (dodecyl trimethylammonium bromide, DTAB) solution in a microfluidic channel at selected ratios of flow rates and reagent concentrations. The methodology ensured a controlled mixing kinetics and a uniform distribution of charges at the mixing interface. The resulting nanoparticles exhibited remarkably well-defined and repeatable size distributions, with hydrodynamic diameters tunable from 50 up to 300 nm and polydispersity index around 0.1 in most cases. Microfluidic-assisted self-assembly may be an efficient way to produce well-controlled polyelectrolyte-based nanoparticles suitable for colloidal science as well as for gene delivery applications.
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Cima I, Wen Yee C, Iliescu FS, Phyo WM, Lim KH, Iliescu C, Tan MH. Label-free isolation of circulating tumor cells in microfluidic devices: Current research and perspectives. BIOMICROFLUIDICS 2013; 7:11810. [PMID: 24403992 PMCID: PMC3568085 DOI: 10.1063/1.4780062] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/17/2012] [Indexed: 05/04/2023]
Abstract
This review will cover the recent advances in label-free approaches to isolate and manipulate circulating tumor cells (CTCs). In essence, label-free approaches do not rely on antibodies or biological markers for labeling the cells of interest, but enrich them using the differential physical properties intrinsic to cancer and blood cells. We will discuss technologies that isolate cells based on their biomechanical and electrical properties. Label-free approaches to analyze CTCs have been recently invoked as a valid alternative to "marker-based" techniques, because classical epithelial and tumor markers are lost on some CTC populations and there is no comprehensive phenotypic definition for CTCs. We will highlight the advantages and drawbacks of these technologies and the status on their implementation in the clinics.
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Droste DW, Iliescu C, Vaillant M, Gantenbein M, De Bremaeker N, Lieunard C, Velez T, Meyer M, Guth T, Kuemmerle A, Chioti A. Lifestyle counseling in patients with carotid arteriosclerosis from Luxemburg should focus more on the reduction of sugar, sodium and saturated fat consumption. BULLETIN DE LA SOCIETE DES SCIENCES MEDICALES DU GRAND-DUCHE DE LUXEMBOURG 2013:28-38. [PMID: 23808108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
BACKGROUND Healthy diet and physical activity improve risk factors for cerebrovascular disease. It is unclear whether patients with carotid artery disease from Luxemburg meet common guideline criteria and whether systematic counseling has a sustained effect. METHODS We assessed anthropometric data, eating habits and physical activity habits in 53 patients with carotid atherosclerosis at baseline, after 4 and 20 weeks, and advised them five times for 30 min to follow a modified Mediterranean diet and to perform moderate physical exercise at least during 30 min/day. RESULTS The patients had a mildly increased BMI (mean 27.6, recommended below 25), they already ate enough vegetables and fruits (mean 485 g daily, recommended at least 400 g), they ate too much sugar (mean 74 g daily) and sodium (mean 2710 mg daily, recommended less than 1500), they consumed 13% of calories from saturated fatty acids (recommended less than 10%), and they already moved sufficiently (62 min daily of moderate and intense physical activity, recommended at least 30 min of moderate physical activity). Lifestyle counseling had a sustained effect on weight, reduction of global caloric intake, carbohydrate and cholesterol intake and on an increase in consumption of poly-unsaturated fatty acids, vegetables and fibres. There was no sustained effect on the consumption of sugar, sodium, and saturated fat. CONCLUSIONS The reduction of sugar, sodium and saturated fat consumption should be stressed more in counselling of this patient group.
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Choudhury D, van Noort D, Iliescu C, Zheng B, Poon KL, Korzh S, Korzh V, Yu H. Fish and Chips: a microfluidic perfusion platform for monitoring zebrafish development. LAB ON A CHIP 2012; 12:892-900. [PMID: 22146879 DOI: 10.1039/c1lc20351g] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We have developed a multi-channel microfluidic perfusion platform for culturing zebrafish embryos and capturing live images of various tissues and organs inside the embryo. The Fish and Chips was micro-fabricated in silicon and glass for reproducibility and accuracy of the microfluidic structure. The microfluidic platform consists of three parts: a microfluidic gradient generator, a row of eight fish tanks, in which the fish embryos are individually placed, and eight output channels. The fluidic gradient generator supports dose-dependent drug and chemical studies. A unique perfusion system ensures a uniform and constant flow of media to the fish tank while the wastes are efficiently removed. The fish tanks restrict the embryo movements, except rotationally, for live imaging of internal tissues and organs. The embryos showed developmental abnormalities under the influence of the drug valproic acid (VPA).
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Iliescu C, Taylor H, Avram M, Miao J, Franssila S. A practical guide for the fabrication of microfluidic devices using glass and silicon. BIOMICROFLUIDICS 2012; 6:16505-1650516. [PMID: 22662101 PMCID: PMC3365353 DOI: 10.1063/1.3689939] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Accepted: 02/08/2012] [Indexed: 05/04/2023]
Abstract
This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow.
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Deschildre A, Béghin L, Salleron J, Iliescu C, Thumerelle C, Santos C, Hoorelbeke A, Scalbert M, Pouessel G, Gnansounou M, Edmé JL, Matran R. Home telemonitoring (forced expiratory volume in 1 s) in children with severe asthma does not reduce exacerbations. Eur Respir J 2011; 39:290-6. [PMID: 21852334 DOI: 10.1183/09031936.00185310] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Some children with severe asthma develop frequent exacerbations despite intensive treatment. We sought to assess the outcome (severe exacerbations and healthcare use, lung function, quality of life and maintenance treatment) of a strategy based on daily home spirometry with teletransmission to an expert medical centre and whether it differs from that of a conventional strategy. 50 children with severe uncontrolled asthma were enrolled in a 12-month prospective study and were randomised into two groups: 1) treatment managed with daily home spirometry and medical feedback (HM) and 2) conventional treatment (CT). The children's mean age was 10.9 yrs (95% confidence interval 10.2-11.6). 44 children completed the study (21 in the HM group and 23 in the CT group). The median number of severe exacerbations per patient was 2.0 (interquartile range 1.0-4.0) in the HM group and 3.0 (1.0-4.0) in the CT group (p=0.38 with adjustment for age). There were no significant differences between the two groups for unscheduled visits (HM 5.0 (3.0-7.0), CT 3.0 (2.0-7.0); p=0.30), lung function (pre-β(2)-agonist forced expiratory volume in 1 s (FEV(1)) p=0.13), Paediatric Asthma Quality of Life Questionnaire scores (p=0.61) and median daily dose of inhaled corticosteroids (p=0.86). A treatment strategy based on daily FEV(1) monitoring with medical feedback did not reduce severe asthma exacerbations.
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Choudhury D, Mo X, Iliescu C, Tan LL, Tong WH, Yu H. Exploitation of physical and chemical constraints for three-dimensional microtissue construction in microfluidics. BIOMICROFLUIDICS 2011; 5:22203. [PMID: 21799710 PMCID: PMC3145229 DOI: 10.1063/1.3593407] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Accepted: 05/02/2011] [Indexed: 05/06/2023]
Abstract
There are a plethora of approaches to construct microtissues as building blocks for the repair and regeneration of larger and complex tissues. Here we focus on various physical and chemical trapping methods for engineering three-dimensional microtissue constructs in microfluidic systems that recapitulate the in vivo tissue microstructures and functions. Advances in these in vitro tissue models have enabled various applications, including drug screening, disease or injury models, and cell-based biosensors. The future would see strides toward the mesoscale control of even finer tissue microstructures and the scaling of various designs for high throughput applications. These tools and knowledge will establish the foundation for precision engineering of complex tissues of the internal organs for biomedical applications.
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Zhang S, Tong W, Zheng B, Susanto TA, Xia L, Zhang C, Ananthanarayanan A, Tuo X, Sakban RB, Jia R, Iliescu C, Chai KH, McMillian M, Shen S, Leo H, Yu H. A robust high-throughput sandwich cell-based drug screening platform. Biomaterials 2011; 32:1229-41. [DOI: 10.1016/j.biomaterials.2010.09.064] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 09/29/2010] [Indexed: 10/18/2022]
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Tay F, Yu L, Iliescu C. Particle Manipulation by Miniaturised Dielectrophoretic Devices. DEFENCE SCI J 2009. [DOI: 10.14429/dsj.59.1564] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Iliescu C, Tresset G, Xu G. Dielectrophoretic field-flow method for separating particle populations in a chip with asymmetric electrodes. BIOMICROFLUIDICS 2009; 3:44104. [PMID: 20216966 PMCID: PMC2835284 DOI: 10.1063/1.3251125] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 09/29/2009] [Indexed: 05/10/2023]
Abstract
This paper presents a field-flow method for separating particle populations in a dielectrophoretic (DEP) chip with asymmetric electrodes under continuous flow. The structure of the DEP device (with one thick electrode that defines the walls of the microfluidic channel and one thin electrode), as well as the fabrication and characterization of the device, was previously described. A characteristic of this structure is that it generates an increased gradient of electric field in the vertical plane that can levitate the particles experiencing negative DEP. The separation method consists of trapping one population to the bottom of the microfluidic channel using positive DEP, while the other population that exhibits negative DEP is levitated and flowed out. Viable and nonviable yeast cells were used for testing of the separation method.
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Abstract
The paper presents a 3-D filter chip employing both mechanical and dielectrophoretic (DEP) filtration, and its corresponding microfabrication techniques. The device structure is similar to a classical capacitor: two planar electrodes, made from a stainless steel mesh, and bonded on both sides of a glass frame filled with round silica beads. The solution with the suspension of particles flows through both the mesh-electrodes and silica beads filter. The top stainless steel mesh (with openings of 60 mum and wires of 30 mum-thickness) provides the first stage of filtration based on mechanical trapping. A second level of filtration is based on DEP by using the nonuniformities of the electric field generated in the capacitor due to the nonuniformities of the dielectric medium. The filter can work also with DC and AC electric fields. The device was tested with yeast cells (Saccharomyces cerevisae) and achieved a maximal trapping efficiency of 75% at an applied AC voltage of 200 V and a flow rate of 0.1 mL/min, from an initial concentration of cells of 5 x 10(5) cells/mL. When the applied frequency was varieted in the range between 20 and 200 kHz, a minimal value of capture efficiency (3%) was notticed at 50 kHz, when yeast cells exhibit negative DEP and the cells are repelled in the space between the beads.
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Tay FE, Yu L, Pang AJ, Iliescu C. Electrical and thermal characterization of a dielectrophoretic chip with 3D electrodes for cells manipulation. Electrochim Acta 2007. [DOI: 10.1016/j.electacta.2006.09.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Yu L, Lee YY, Tay FEH, Iliescu C. Spray Coating of Photoresist for 3D Microstructures with Different Geometries. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/34/1/155] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ji J, Tay FE, Miao J, Iliescu C. Microfabricated Silicon Microneedle Array for Transdermal Drug Delivery. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/34/1/186] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Ong YY, Chen BT, Tay FEH, Iliescu C. Process Analysis and Optimization on PECVD Amorphous Silicon on Glass Substrate. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/34/1/134] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Yu L, Tay FEH, Xu G, Chen B, Avram M, Iliescu C. Adhesive bonding with SU-8 at wafer level for microfluidic devices. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/34/1/128] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Difficult asthma in children is defined as the persistence of exacerbations or frequent symptoms requiring rescue bronchodilator, or persistent airway obstruction in spite of treatment with inhaled steroid >/= 800 microg/d beclomethasone or equivalent and beta-2 long acting agonist. Management of difficult asthma in children first requires to identify conditions that may mimic asthma, asthma with bad compliance to treatment, and difficult asthma in relation with avoidable factors that worsen symptoms. The pathological bases of genuine difficult asthma remain unknown. Different patterns have been described according to the cells that are involved (eosinophil, neutrophil), the degree of airway remodeling, or the distal localization of the lesions. Difficult asthma requires specialized management including airway inflammation evaluation. Studies on bronchoalveolar lavage and bronchial mucosa biopsies will perhaps help to better understand the pathophysiology and to improve the management.
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Tillie-Leblond I, Scherpereel A, Iliescu C. Lˈaspergillose bronchopulmonaire allergique. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0335-7457(02)00143-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Bergeron C, Iliescu C, Thiesse P, Bouvier R, Dijoud F, Ranchere-Vince D, Basset T, Chappuis JP, Buclon M, Frappaz D, Brunat-Mentigny M, Philip T. Does nephroblastomatosis influence the natural history and relapse rate in Wilms' tumour? A single centre experience over 11 years. Eur J Cancer 2001; 37:385-91. [PMID: 11239761 DOI: 10.1016/s0959-8049(00)00409-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The presence of multifocal or diffuse nephrogenic rests (NRs) in one or both kidneys is termed nephroblastomatosis (Nbm). Nbm may be a predisposing factor for Wilms' tumour (WT). The aim of this retrospective study was to evaluate the impact of Nbm on the outcome of WT in children. We assessed the outcome of 81 children with Wilms tumours and practical implications of Nbm in the treatment and follow-up. All the pathology slides have been reviewed in 1997. 63 had WT without Nbm (group A) and 18 had WT associated with Nbm (group B). There was no statistical difference between the two groups according to the age at diagnosis and histology. Clinical abnormalities were more frequent in group B (33 versus 8%). There was no statistical difference between the percentage of stage IV in both groups, but bilaterality (stage V) was present only in the group B. Relapse was observed in 20/81 patients (25%): 11 (17%) in group A and 9 (50%) in group B. Mean delay of relapse was longer (25 months) in group B than in group A (10 months). For the whole population, with a median follow-up of 9 years, the event-free survival (EFS) and the overall survival (OS) probabilities were respectively 74%+/-10 and 83%+/-9 at 120 months. The difference in EFS between groups A (82+/-9%) and B (38%+/-29) was significant (P=0.004). The discovery of Nbm in the non-tumoral part of the kidney with WT can be an adverse factor and in particular favours the subsequent development of a new Wilms tumour. It justifies separate follow-up guidelines.
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