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Anandi Martin - One of the best experts on this subject based on the ideXlab platform.

  • resazurin microtiter assay for isoniazid rifampicin ethambutol and streptomycin resistance detection in mycobacterium tuberculosis updated meta analysis
    The International Journal of Mycobacteriology, 2014
    Co-Authors: Ahmet Yilmaz Coban, Juan Carlos Palomino, Aydin Deveci, Ahmet Tevfik Sunter, Anandi Martin
    Abstract:

    Abstract Aims The present meta-analysis aims to assess the evidence regarding the diagnostic accuracy and performance characteristics of the colorimetric Redox Indicator (CRI) assay with a special emphasis on the use of the resazurin microtiter assay (REMA) for determination of primary anti-tuberculosis drug resistance. Subject and methods By updating previous literature searches in Medline PubMed, ISI Web, Web of Science and Google academic databases of the REMA test for determination of primary anti-tuberculosis drug resistance, this meta-analysis includes 14 studies for isoniazid (INH); 15 studies for rifampicin (RIF); 6 studies for streptomycin (STR); and 5 studies for ethambutol (EMB). SROC curve analysis was performed for meta-analysis and diagnostic accuracy was summarized. Results Pooled sensitivity was 96% (94–98%) for INH, 97% (95–98%) for RIF, 92% (87–96%) for EMB and 92% (88–95%) for STR. Pooled specificity for INH, RIF, EMB and STR was 96% (95–98%), 99% (98–99%), 86% (81–89%) and 90% (87–93%), respectively. Susceptibility testing results had been obtained in 8–9 days. Conclusion In conclusion, REMA seems to be a reliable test for the determination of multi-drug resistant (MDR) isolates in laboratories with limited resources. However, few studies for STR and EMB have been found, and cost-effectiveness studies need to be determined to recommend its widespread use.

  • rapid identification and drug susceptibility testing of mycobacterium tuberculosis standard operating procedure for non commercial assays part 3 colorimetric Redox Indicator assay v1 3 12
    Journal of Laboratory Physicians, 2012
    Co-Authors: Sarman Singh, Parveen Kumar, Shreya Sharma, Francis Mumbowa, Anandi Martin, Nicolas Durier
    Abstract:

    The previous two standard operating procedures (SOPs) related to the culture and drug susceptibility testing (DST) of Mycobacterium tuberculosis with the microscopic observation drug susceptibility assay (Part 1) and nitrate reductase assay (Part 2). The present SOP is devoted to a third non-commercial culture and DST method known as colorimetric Redox Indicator assay (CRI). As its name indicates, the CRI detects the ability of the M. tuberculosis to reduce the colored oxidation-reduction Indicator when added to a liquid culture of M. tuberculosis, after exposing the growth to different anti-mycobacterial drugs. The change in the color of the Indicator denotes the proportionate number of viable Mycobacteria in the medium. The identification and DST results can be obtained in 7-8 days. This SOP document has been developed through the culture and DST subgroup of the STOP tuberculosis (TB) Partnership New Diagnostic Working Group. It is intended for laboratories that would want to use or already use this rapid non-commercial method for culture identification and DST of M. tuberculosis, notably in resource-constraint settings in Asia and Africa.

  • multicentre laboratory validation of the colorimetric Redox Indicator cri assay for the rapid detection of extensively drug resistant xdr mycobacterium tuberculosis
    Journal of Antimicrobial Chemotherapy, 2011
    Co-Authors: Anandi Martin, Fabienne Paasch, Sven Docx, Krista Fissette, Belen Imperiale, Wellman Ribon, Liliana Andrea Gonzalez, Jim Werngren, Anna Engstrom, Girts Skenders
    Abstract:

    Conclusions: Results demonstrate that the CRI assay is an accurate method for the rapid detection of XDR Mycobacterium tuberculosis. The CRI assay is faster than the conventional drug susceptibility testing method using solid medium, has the same turnaround time as the BACTEC MGIT 960 system, but is less expensive, and could be an adequate method for low-income countries.

  • systematic review and meta analysis of data on colorimetric Redox Indicator methods cri for rapid diagnosis of drug resistant tuberculosis
    2009
    Co-Authors: Anandi Martin
    Abstract:

    Summary The emergence of multidrug-resistant tuberculosis (MDRTB), defined as resistance to at least isoniazid and rifampicin, which are two essential drugs used for the treatment of TB, is a major problem in the control of the disease. Because of the long period required by conventional methods to detect drug resistance in M. tuberculosis , several new approaches have been proposed in recent years. For reference laboratories in high-burden countries, culture is the first step to perform drug susceptibility testing (DST). Current conventional methods for DST using LowensteinJenssen or the agar-based medium require a minimum of 3-6 weeks to produce definitive results. The commercial liquid-medium BACTEC MGIT 960 reduces the turnaround time but is expensive and places higher demands on equipment to be routinely used in poor-resource

  • colorimetric Redox Indicator methods for the rapid detection of multidrug resistance in mycobacterium tuberculosis a systematic review and meta analysis
    Journal of Antimicrobial Chemotherapy, 2007
    Co-Authors: Anandi Martin, Francoise Portaels, Juan Carlos Palomino
    Abstract:

    Objectives: With the spread of multidrug-resistant tuberculosis (MDR-TB) there is increasing demand for new accurate and cost-effective tools for rapid drug susceptibility testing (DST), particularly for developing countries. The reference standard method used today for DST is very slow and cumbersome. Colorimetric assays using Redox Indicators have been proposed to be used in low-resource countries as rapid alternative culture methods for the detection of resistance especially to rifampicin and isoniazid. These methods appear as promising new tools but their accuracy has not been systematically evaluated. Methods: We did a meta-analysis to evaluate the accuracy of the colorimetric assays for the detection of rifampicin and isoniazid-resistant tuberculosis among clinical isolates. We searched Medline, PubMed (NCBI), Global health-CAB, EJS-E (EbscoHost), ISI Web, Web of Science and IFCC databases and contacted authors it additional information was needed. Results: Eighteen studies met our inclusion criteria for rifampicin resistance detection and 16 for isoniazid. We used a summary receiver operating characteristic (SROC) curve to perform meta-analysis and summarize diagnostic accuracy. For both drugs, all studies had a sensitivity and specificity that ranged between 89% and 100%. Conclusions: There is evidence that colorimetric methods are highly sensitive and specific for the rapid detection of MDR-TB. These new tools could offer affordable technologies for TB laboratories especially in places where resources are limited and where the prevalence of MDR-TB is important and make TB control efforts more effective. Additional studies are needed in high MDR prevalence countries and cost-effectiveness analysis to have more evidence on the utility of these methods. Future developments to detect resistance directly from smear-positive sputum specimens should be taken into consideration to speed up the process.

Elena E Ferapontova - One of the best experts on this subject based on the ideXlab platform.

  • picomolar sensitive and snp selective off on hairpin genosensor based on structure tunable Redox Indicator signals
    Biosensors and Bioelectronics, 2018
    Co-Authors: Laszlo Kekedynagy, Karina Dalsgaard Sorensen, Elena E Ferapontova
    Abstract:

    Abstract A robust and sensitive electrochemical assay for chrononocoulometric detection of nucleic acids at a single nucleotide polymorphism (SNP) level has been developed. The assay exploits hybridization-induced conformational switching of gold-tethered TP53-specific 33-mer and truncated 20-mer hairpin DNA probes and methylene blue (MB) as an intercalating Redox Indicator. We show that by fine tuning of MB-DNA intercations the enhanced binding of MB to hybrids formed with a cancer-biomarker sequence can be achieved, and that results in robust “off-on” sensing of hybridization, while the stem-loop probe design allows minimized, independent of the DNA length background signals. Both DNA probes were sensitive to the presence of SNP in the targeted DNA sequence already at 10 pM. DNA levels, and the robust “off-on” discrimination of 10 pM perfectly-matched DNA from 50 nM SNP-containing DNA was achieved by time-adjusted chronocoulometry. This label-free hairpin DNA strategy allows systematic design of DNA assays for fast, robust and inexpensive genetic analysis in excessive mixtures of structurally-related DNA sequences and was used for specific analysis of prostate-cancer-realted cellular microRNA in total RNA samples isolated from LNCaP and BPH1 cells.

  • dna interactions with a methylene blue Redox Indicator depend on the dna length and are sequence specific
    Analyst, 2010
    Co-Authors: Elaheh Farjami, Elena E Ferapontova, Lilia Clima, Kurt V Gothelf
    Abstract:

    A DNA molecular beacon approach was used for the analysis of interactions between DNA and Methylene Blue (MB) as a Redox Indicator of a hybridization event. DNA hairpin structures of different length and guanine (G) content were immobilized onto gold electrodes in their folded states through the alkanethiol linker at the 5'-end. Binding of MB to the folded hairpin DNA was electrochemically studied and compared with binding to the duplex structure formed by hybridization of the hairpin DNA to a complementary DNA strand. Variation of the electrochemical signal from the DNA-MB complex was shown to depend primarily on the DNA length and sequence used: the G-C base pairs were the preferential sites of MB binding in the duplex. For short 20 nts long DNA sequences, the increased electrochemical response from MB bound to the duplex structure was consistent with the increased amount of bound and electrochemically readable MB molecules (i.e. MB molecules that are available for the electron transfer (ET) reaction with the electrode). With longer DNA sequences, the balance between the amounts of the electrochemically readable MB molecules bound to the hairpin DNA and to the hybrid was opposite: a part of the MB molecules bound to the long-sequence DNA duplex seem to be electrochemically mute due to long ET distance. The increasing electrochemical response from MB bound to the short-length DNA hybrid contrasts with the decreasing signal from MB bound to the long-length DNA hybrid and allows an "off"-"on" genosensor development.

Mahin Keshavarz - One of the best experts on this subject based on the ideXlab platform.

  • a novel label free electrochemical mirna biosensor using methylene blue as Redox Indicator application to breast cancer biomarker mirna 21
    Biosensors and Bioelectronics, 2016
    Co-Authors: Hossainali Rafieepour, Mohsen Behpour, Mahin Keshavarz
    Abstract:

    Small noncoding microRNAs (miRNAs) have emerged as ideal noninvasive biomarkers for early-phase cancer detection. In this report, a label-free and simple electrochemical miRNA biosensor is developed based on employing methylene blue (MB) as a Redox Indicator. The successfully immobilization of the single strand DNA (ss-DNA) probe and hybridization with the target miRNA sequence were confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. Differential pulse voltammetry (DPV) technique was used to record the oxidation peak current of MB under optimal condition and an increase in the peak current was observed after hybridization. By employing this strategy, miRNA can detect in a range from 0.1 to 500.0 pM with a relatively low detection limit of 84.3 fM. The electrochemical response of MB on ss-DNA and duplex of miRNA/DNA was characterized by CV and chronocoulometry method. The linear relation between the Redox peak currents (Ip) and scan rate (ν) indicates that the electron transfer (ET) between MB and the electrode surface was mediated by the miRNA/DNA π-stacked duplex. The value of surface coverage (Γ) was calculated that indicated increase amount of MB on the surface of modified electrode after hybridization event and revealed the adsorption of MB at modified electrode is monolayer. Also, the electron transfer rate constants (ks) of MB were estimated. The results of kinetic analysis were confirmed by chronocoulometry method. The discrimination ability of miRNA biosensor even against a noncomplementary target was also studied. Consequently, this strategy will be valuable for sensitive, selective and label-free detection of miRNA.

Arben Merkoci - One of the best experts on this subject based on the ideXlab platform.

  • nanochannel array device operating through prussian blue nanoparticles for sensitive label free immunodetection of a cancer biomarker
    Biosensors and Bioelectronics, 2015
    Co-Authors: Marisol Espinozacastaneda, Alfredo De La Escosuramuniz, Alejandro Chamorro, Carmen De Torres, Arben Merkoci
    Abstract:

    A novel nanochannel array (NC) device that operates through Prussian blue nanoparticles (PBNPs) as Redox Indicator for sensitive label free immunodetection of a cancer biomarker is presented. Stable and narrow-sized (around 4 nm) PBNPs, protected by polyvinylpyrrolidone, exhibited a well-defined and reproducible Redox behavior and were successfully applied for the voltammetric evaluation of the nanochannels (20 nm pore sized) blockage due to the immunocomplex formation. The bigger size of the PBNPs compared with ionic Indicators such as the [Fe(CN)6](4-/3-) system leads to an increase in the steric effects hindering their diffusion toward the signaling electrode which in turn is transduced to an improvement of the detection limit from 200 µg mL(-1) to 34 pg human IgG mL(-1). This novel and effective PBNPs-NC technology for the detection of small proteins captured inside the nanochannels is successfully applied for the quantification of a cancer biomarker (parathyroid hormone-related protein, PTHrP) in a real clinical scenario such as cell culture medium. The achieved label-free detection of PTHrP at levels of 50 ng mL(-1) is with great interest to study relevant functions that this protein exerts in normal tissues and cancer.

  • a nanochannel nanoparticle based filtering and sensing platform for direct detection of a cancer biomarker in blood
    Small, 2011
    Co-Authors: Alfredo De La Escosuramuniz, Arben Merkoci
    Abstract:

    A rapid nanochannel-based immunoassay capable of the filtering and subsequent detection of proteins in whole blood without any sample preparation is described. This is accomplished by using a nanoporous/nanochannel membrane modified with antibodies, the conductivity of which toward a Redox Indicator is tuned by primary and secondary immunoreactions with proteins and gold nanoparticles. This interesting nanopore blockage by gold nanoparticles is enhanced by silver deposition that further decreases the diffusion of the signaling Indicator through the nanochannel. The efficiency of the nanochannels to act as immunoreaction platforms including the use of nanoparticles is also monitored by microscopic techniques. Successful detection of immunoglobulins including a cancer biomarker is achieved in buffer as well as in whole blood. This system constitutes an efficient immunoassay capable of detecting up to 52 U mL−1 of CA15-3. The developed nanochannel/nanoparticle-based device can be used for several other proteins and extended also to DNA detection with interest not only for diagnostics but also environmental monitoring, food analysis, safety, and security applications.

Panote Thavarungkul - One of the best experts on this subject based on the ideXlab platform.

  • pyrrolidinyl pna polypyrrole silver nanofoam electrode as a novel label free electrochemical mirna 21 biosensor
    Biosensors and Bioelectronics, 2018
    Co-Authors: Tawatchai Kangkamano, Apon Numnuam, Warakorn Limbut, Proespichaya Kanatharana, Tirayut Vilaivan, Panote Thavarungkul
    Abstract:

    Abstract A label-free electrochemical miRNA biosensor was developed based on a pyrrolidinyl peptide nucleic acid (acpcPNA)/polypyrrole (PPy)/silver nanofoam (AgNF) modified electrode. The AgNF was electrodeposited as Redox Indicator on a gold electrode, which was then functionalized with an electropolymerized layer of PPy, a conducting polymer, to immobilize the PNA probes. The fabrication process was investigated by electrochemical impedance spectroscopy. The biosensor was used to detect miRNA-21, a biomarker abnormally expressed in most cancers. The signal was monitored by the change in current of the AgNF Redox reaction before and after hybridization using cyclic voltammetry. Two PNA probe lengths were investigated and the longer probe exhibited a better performance. Nucleotide overhangs on the electrode side affected the signal more than overhangs on the solution side due to the greater insulation of the sensing surface. Under optimal conditions, the electrochemical signal was proportional to miRNA-21 concentrations between 0.20 fM and 1.0 nM, with a very low detection limit of 0.20 fM. The biosensor showed a high specificity which could discriminate between complementary, single-, doubled-base mismatched, and non-complementary targets. Three out of the seven tested plasma samples provided detectable concentrations (63 ± 4, 111 ± 4 and 164 ± 7 fM). The sensor also showed good recoveries (81–119%). The results indicated the possibilities of this biosensor for analysis without RNA extraction and/or amplification, making the sensor potentially useful for both the prognosis and diagnosis of cancer in clinical application.