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1.
J Mass Spectrom Adv Clin Lab ; 31: 40-48, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38375485

RESUMEN

Introduction: The accurate quantification of amyloid beta (Aß) peptides in cerebrospinal fluid (CSF) is crucial for Alzheimer's disease (AD) research, particularly in terms of preclinical and biomarker studies. Traditional methods, such as the enzyme-linked immunosorbent assay (ELISA), have limitations. These include high costs, labor intensity, lengthy processes, and the possibility of cross-reactivity. Objectives: The primary objectives of this research were twofold: to comprehensively characterize Aß peptides and to develop a reliable and accurate method for the simultaneous quantification of Aß 1-40 and Aß 1-42 peptides in surrogate CSF that is traceable to the International System of Units (SI). Methods: We developed a novel method that combined solid phase extraction (SPE) with isotope dilution liquid chromatography/tandem mass spectrometry (ID-LC/MSMS). SPE was employed to efficiently eliminate matrix interferences, while [15N] Aß1-40 and [15N] Aß1-42 served as internal standards to improve accuracy. In addition, we introduced Peptide Impurity Corrected Amino Acid Analysis (PICAA) to ensure traceability to the SI and reliable quantification of Aß peptides. Results: The developed platform demonstrated a linear calibration range of 300-20000 pg/ml for both Aß1-42 and Aß1-40 peptides, accompanied by strong correlation coefficients greater than 0.995. Quality Control (QC) samples demonstrated an accuracy of at least 90.0 %. Conclusion: The enhanced specificity and flexibility of the developed platform potentially have implications for Alzheimer's disease diagnosis and future investigations of novel Aß peptide biomarkers.

2.
Rev Assoc Med Bras (1992) ; 68(9): 1161-1165, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36228247

RESUMEN

OBJECTIVE: Hepatocellular carcinoma is the most common primary malignant liver tumor. Mitochondrial DNA copy number has been shown to be associated with various malignancies. However, there has not been any study on the absolute quantification of mtDNA copy number in hepatocellular carcinoma. The aim of this study was to develop a new method for absolute quantification of mtDNA copy number and to relatively quantify the variations in the mtDNA copy number in hepatocellular carcinoma patients in comparison with healthy individuals. METHODS: Venous blood samples were collected from both hepatocellular carcinoma patients (34) and healthy individuals (34). Circulating cell-free DNAs were isolated and the relative quantification of mtDNA copy number variation was determined using quantitative polymerase chain reaction and digital polymerase chain reaction. RESULTS: It was found that the relative mtDNA copy number was significantly decreased in hepatocellular carcinoma patients in comparison with the control group (p<0.05). The median (range) and average of relative mtDNA/ß-actin gene of the patients were determined as 42.8 cp/µL (11.1-88.5) and 45.1 cp/µL, respectively, while the median (range) and average relative mtDNA/ß-actin gene of the control group were determined as 102.8 cp/µL (55.1-291.8) and 138.7 cp/µL, respectively (p<0.05). When quantitative polymerase chain reaction and digital polymerase chain reaction were compared, mtDNA/ß-actin gene copy number ratio of digital polymerase chain reaction results was found to be 1.76-fold more than that of quantitative polymerase chain reaction results. CONCLUSION: Circulating mtDNA copy number was decreased in hepatocellular carcinoma patients in comparison with healthy individuals, and we suggest that it can be used as a noninvasive biomarker for hepatocellular carcinoma diagnosis in the future.


Asunto(s)
Carcinoma Hepatocelular , Neoplasias Hepáticas , Actinas , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patología , Variaciones en el Número de Copia de ADN , ADN Mitocondrial/genética , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patología
3.
Rev. Assoc. Med. Bras. (1992, Impr.) ; 68(9): 1161-1165, Sept. 2022. tab
Artículo en Inglés | LILACS-Express | LILACS | ID: biblio-1406664

RESUMEN

SUMMARY OBJECTIVE: Hepatocellular carcinoma is the most common primary malignant liver tumor. Mitochondrial DNA copy number has been shown to be associated with various malignancies. However, there has not been any study on the absolute quantification of mtDNA copy number in hepatocellular carcinoma. The aim of this study was to develop a new method for absolute quantification of mtDNA copy number and to relatively quantify the variations in the mtDNA copy number in hepatocellular carcinoma patients in comparison with healthy individuals. METHODS: Venous blood samples were collected from both hepatocellular carcinoma patients (34) and healthy individuals (34). Circulating cell-free DNAs were isolated and the relative quantification of mtDNA copy number variation was determined using quantitative polymerase chain reaction and digital polymerase chain reaction. RESULTS: It was found that the relative mtDNA copy number was significantly decreased in hepatocellular carcinoma patients in comparison with the control group (p<0.05). The median (range) and average of relative mtDNA/β-actin gene of the patients were determined as 42.8 cp/μL (11.1-88.5) and 45.1 cp/μL, respectively, while the median (range) and average relative mtDNA/β-actin gene of the control group were determined as 102.8 cp/μL (55.1-291.8) and 138.7 cp/μL, respectively (p<0.05). When quantitative polymerase chain reaction and digital polymerase chain reaction were compared, mtDNA/β-actin gene copy number ratio of digital polymerase chain reaction results was found to be 1.76-fold more than that of quantitative polymerase chain reaction results. CONCLUSION: Circulating mtDNA copy number was decreased in hepatocellular carcinoma patients in comparison with healthy individuals, and we suggest that it can be used as a noninvasive biomarker for hepatocellular carcinoma diagnosis in the future.

4.
Anal Bioanal Chem ; 413(13): 3411-3419, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33738508

RESUMEN

SARS-CoV-2 in vitro transcribed RNA reference materials (RM), UME RM 2019 and UME RM 2020, were produced by Scientific and Technological Research Council of Turkey (TUBITAK), National Metrology Institute (UME), to be used as a quality control material for SARS-CoV-2 measurements, in liquid-frozen and lyophilized forms, respectively. These RNA RMs include ten internationally recommended SARS-CoV-2 target gene fragments (Pasteur-RdRp-IP2, Pasteur-RdRp-IP4, Charite-E, Charite-RdRp, CDC-N1, CDC-N2, China CDC-ORF1ab, China CDC-N, Hong Kong-ORF1b, and Hong Kong-N) for virus detection and one human gene fragment (RNase P) as an internal control. Two different platforms, RT-qPCR and RT-ddPCR, were used to characterize UME RM 2019 (UME RM 2020 was only characterized with RT-qPCR). The homogeneity studies were evaluated by RT-qPCR. According to these results, it has been shown that both reference materials are homogeneous for intended use. Short-term studies were also conducted similarly for mimicking transport conditions and UME RM 2020, which is produced in lyophilized form, unlike other reference materials available in the market, provides convenience for users by ensuring that the reference material remains stable for 17 days even at 45 °C temperature. The lyophilized formulation of the reference material had greater stability which would allow it to be shipped without cooling items. The development of such RNA reference materials provides quality control for existing and newly designed RNA-based virus detection tests and it helps the prevention and control of epidemics.


Asunto(s)
COVID-19/virología , ARN Viral/genética , SARS-CoV-2/genética , Secuencia de Bases , Prueba de Ácido Nucleico para COVID-19/métodos , Prueba de Ácido Nucleico para COVID-19/normas , Humanos , Estabilidad del ARN , ARN Viral/química , ARN Viral/normas , Estándares de Referencia , SARS-CoV-2/química
5.
OMICS ; 24(12): 756-765, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33085568

RESUMEN

Thermophilic microorganisms that thrive in extreme environments are of great importance because they express heat-resistant enzymes with the potential to serve as biocatalysts in industrial applications. Thermal proteome profiling (TPP) is a multiplexed quantitative mass spectrometry method for analyses of structural information and melting behavior of thousands of proteins, simultaneously determining the thermal denaturation profiles of each protein. We report, in this study, TPP applied to a thermophilic bacterial proteome, a recently isolated strain of Geobacillus thermoleovorans named as ARTRW1. The proteome was investigated in terms of thermostable enzymes that are relevant to industrial applications. In this study, we present the thermostability profiles of its 868 proteins. The majority of G. thermoleovorans proteome was observed to melt between 62.5°C and 72°C, with melting point (Tm) mean value of 68.1°C ± 6.6°C. Unfolding characteristics of several enzymes, including amylase, protease, and lipase, were demonstrated which are highly informative in terms of their applicability to specific industrial processes. A significant correlation was observed between protein melting temperature and the structural features such as molecular weight and abundance, whereas correlations were modest or weak in relation to the α-helix structure percentages. Taken together, we demonstrated a system-wide melting profile analysis of a thermal proteome and listed proteins with elevated Tm values that are highly promising for applications in medicine, food engineering, and cosmetics in particular. The extracted Tm values were found similar to those obtained by biophysical methods applied to purified proteins. TPP analysis has significant industrial and biomedical potentials to accelerate thermophilic enzyme research and innovation.


Asunto(s)
Proteínas Bacterianas/metabolismo , Geobacillus/metabolismo , Proteoma , Proteómica , Proteínas Bacterianas/química , Espectrometría de Masas , Desnaturalización Proteica , Ingeniería de Proteínas , Estabilidad Proteica , Proteómica/métodos , Temperatura
6.
Microbiol Resour Announc ; 9(24)2020 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-32527772

RESUMEN

The thermophilic microorganism Geobacillus thermoleovorans ARTRW1 was isolated from water samples collected in the Armutlu hot spring in Turkey. Here, the whole-genome sequence and its annotations are reported.

7.
Cytometry B Clin Cytom ; 96(6): 508-513, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-30790450

RESUMEN

BACKGROUND: Over 2,000 people a year in the United Kingdom need a bone marrow or blood stem cell transplant. It is important to accurately quantify the hematopoietic stem cells to predict whether the transplant will be successful in replenishing the immune system. However, they are present at low frequency, which complicates accurate quantification. The current gold standard method is single-platform flow cytometry using internal reference counting beads to determine the concentration of CD34 cells. However, volumetric flow cytometers have the ability to measure the acquisition volume, which removes the need for reference beads for calculation of cell concentrations. METHOD: In this study, we compared both methods for calculating CD34 cell concentrations in volumetric cytometers, using either the volume reading or the number of reference beads for calculation. In addition, the uncertainty of measurement for each method was estimated. RESULTS: The results show that both methods have similar uncertainties of measurement. Regression analysis showed low to no statistical difference in CD34 cell concentrations obtained with each method. CONCLUSIONS: Overall, this study suggests that the volumetric method is a valid approach but that the adoption of this technology may be hindered without some form of external calibration of volume readings to increase confidence in the measurement. © 2019 The Authors. Cytometry Part B: Clinical Cytometry published by Wiley Periodicals, Inc. on behalf of International Clinical Cytometry Society.


Asunto(s)
Antígenos CD34/análisis , Citometría de Flujo , Células Madre Hematopoyéticas/citología , Recuento de Células , Humanos , Análisis de Regresión
8.
Analyst ; 144(4): 1379-1385, 2019 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-30569044

RESUMEN

In this study, we provide a method using fluorescently labeled oligonucleotides for the diagnosis of microorganisms producing nucleases in real time, while growing them in culture media. The detection of such microorganisms was possible in a short period of time, as short as 10 minutes up to a maximum of 8 hours, depending on the bacterial density. We also showed the suitability of this new method for determination of minimum inhibitory concentration (MIC) in culture media in a very short period of time, compared to conventional methods. We believe that it can make a significant contribution to gain new insights for analysis of complex materials such as clinical samples, food samples and environmental samples.


Asunto(s)
Técnicas Bacteriológicas/métodos , Desoxirribonucleasas/análisis , Colorantes Fluorescentes/química , Sondas de Oligonucleótidos/química , Antiinfecciosos/farmacología , Candida albicans/enzimología , Candida albicans/aislamiento & purificación , Medios de Cultivo/química , Enterococcus faecalis/enzimología , Enterococcus faecalis/aislamiento & purificación , Escherichia coli/enzimología , Escherichia coli/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/enzimología , Staphylococcus aureus/aislamiento & purificación
9.
Clin Chem ; 64(9): 1296-1307, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29903874

RESUMEN

BACKGROUND: Genetic testing of tumor tissue and circulating cell-free DNA for somatic variants guides patient treatment of many cancers. Such measurements will be fundamental in the future support of precision medicine. However, there are currently no primary reference measurement procedures available for nucleic acid quantification that would support translation of tests for circulating tumor DNA into routine use. METHODS: We assessed the accuracy of digital PCR (dPCR) for copy number quantification of a frequently occurring single-nucleotide variant in colorectal cancer (KRAS c.35G>A, p.Gly12Asp, from hereon termed G12D) by evaluating potential sources of uncertainty that influence dPCR measurement. RESULTS: Concentration values for samples of KRAS G12D and wild-type plasmid templates varied by <1.2-fold when measured using 5 different assays with varying detection chemistry (hydrolysis, scorpion probes, and intercalating dyes) and <1.3-fold with 4 commercial dPCR platforms. Measurement trueness of a selected dPCR assay and platform was validated by comparison with an orthogonal method (inductively coupled plasma mass spectrometry). The candidate dPCR reference measurement procedure showed linear quantification over a wide range of copies per reaction and high repeatability and interlaboratory reproducibility (CV, 2%-8% and 5%-10%, respectively). CONCLUSIONS: This work validates dPCR as an SI-traceable reference measurement procedure based on enumeration and demonstrates how it can be applied for assignment of copy number concentration and fractional abundance values to DNA reference materials in an aqueous solution. High-accuracy measurements using dPCR will support the implementation and traceable standardization of molecular diagnostic procedures needed for advancements in precision medicine.


Asunto(s)
Reacción en Cadena de la Polimerasa/métodos , Medicina de Precisión , Variaciones en el Número de Copia de ADN , Humanos , Espectrometría de Masas , Reproducibilidad de los Resultados
10.
Phytochem Anal ; 28(6): 541-549, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28722248

RESUMEN

INTRODUCTION: Salvia, an important and widely available member of Lamiaceae family. Although comparative analysis on secondary metabolites in several Salvia species from Turkey has been reported, their hallucinogenic chemicals have not been screened thoroughly. OBJECTIVE: This study provides LC-MS/MS analysis of 40 Salvia species for screening their psychoactive constituents of salvinorin A and salvinorin B. 5S-rRNA gene non-coding region of Salvia plants was sequenced, aligned and compared with that sequence of Salvia divinorum plant. METHODOLOGY: Targeted molecules of salvinorin A and salvinorin B were quantified, using LC-MS/MS, from all aerial parts of 40 Salvia species, collected from different parts of Turkey. Regions of 5S-rRNA gene from different species were amplified by polymerase chain reaction and DNA sequences were aligned with Salvia divinorum DNA sequences. RESULTS: Very few of the Salvia species (S. recognita, S. cryptantha and S. glutinosa) contained relatively high levels of salvinorin A (212.86 ± 20.46 µg/g, 51.50 ± 4.95 µg/g and 38.92 ± 3.74 µg/g, respectively). Salvinorin B was also found in Salvia species of S. potentillifolia, S. adenocaulon and S. cryptantha as 2351.99 ± 232.22 µg/g, 768.78 ± 75.90 µg/g and 402.24 ± 39.71 µg/g, respectively. The sequences of 5S-rRNA gene of 40 different Salvia species were presented and it was found that none of the Salvia species in Turkey had similar DNA sequence to Salvia divinorum plant. CONCLUSION: This is the first report of screening 40 Salvia species in Turkey according to their psychoactive constituents, salvinorin A and salvinorin B and their genomic structures. It is possible that some of these Salvia species may exhibit some psycho activity. Thus, they need to be screened further. Copyright © 2017 John Wiley & Sons, Ltd.


Asunto(s)
Alucinógenos/química , Salvia/química , Salvia/genética , Cromatografía Liquida/métodos , ADN de Plantas/genética , Regulación de la Expresión Génica de las Plantas , Genoma de Planta , Filogenia , Especificidad de la Especie , Espectrometría de Masas en Tándem/métodos , Turquía
11.
Anal Bioanal Chem ; 409(10): 2601-2614, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28124757

RESUMEN

Quantitative PCR (qPCR) is an important tool in pathogen detection. However, the use of different qPCR components, calibration materials and DNA extraction methods reduces comparability between laboratories, which can result in false diagnosis and discrepancies in patient care. The wider establishment of a metrological framework for nucleic acid tests could improve the degree of standardisation of pathogen detection and the quantification methods applied in the clinical context. To achieve this, accurate methods need to be developed and implemented as reference measurement procedures, and to facilitate characterisation of suitable certified reference materials. Digital PCR (dPCR) has already been used for pathogen quantification by analysing nucleic acids. Although dPCR has the potential to provide robust and accurate quantification of nucleic acids, further assessment of its actual performance characteristics is needed before it can be implemented in a metrological framework, and to allow adequate estimation of measurement uncertainties. Here, four laboratories demonstrated reproducibility (expanded measurement uncertainties below 15%) of dPCR for quantification of DNA from human cytomegalovirus, with no calibration to a common reference material. Using whole-virus material and extracted DNA, an intermediate precision (coefficients of variation below 25%) between three consecutive experiments was noted. Furthermore, discrepancies in estimated mean DNA copy number concentrations between laboratories were less than twofold, with DNA extraction as the main source of variability. These data demonstrate that dPCR offers a repeatable and reproducible method for quantification of viral DNA, and due to its satisfactory performance should be considered as candidate for reference methods for implementation in a metrological framework.


Asunto(s)
Infecciones por Citomegalovirus/diagnóstico , Citomegalovirus/genética , ADN Viral/análisis , Ensayos de Aptitud de Laboratorios/normas , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Citomegalovirus/aislamiento & purificación , Infecciones por Citomegalovirus/genética , Infecciones por Citomegalovirus/virología , ADN Viral/genética , Humanos , Reproducibilidad de los Resultados
12.
Food Chem ; 221: 1253-1257, 2017 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-27979086

RESUMEN

Preventing adulteration of meat and meat products with less desirable or objectionable meat species is important not only for economical, religious and health reasons, but also, it is important for fair trade practices, therefore, several methods for identification of meat and meat products have been developed. In the present study, ten different DNA extraction methods, including Tris-EDTA Method, a modified Cetyltrimethylammonium Bromide (CTAB) Method, Alkaline Method, Urea Method, Salt Method, Guanidinium Isothiocyanate (GuSCN) Method, Wizard Method, Qiagen Method, Zymogen Method and Genespin Method were examined to determine their relative effectiveness for extracting DNA from meat samples. The results show that the salt method is easy to perform, inexpensive and environmentally friendly. Additionally, it has the highest yield among all the isolation methods tested. We suggest this method as an alternative method for DNA isolation from meat and meat products.


Asunto(s)
ADN/aislamiento & purificación , Productos de la Carne/análisis , Carne/análisis , Compuestos de Cetrimonio/química , ADN/análisis , Reacción en Cadena de la Polimerasa , Espectrometría de Fluorescencia
13.
PLoS One ; 11(12): e0168755, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-28036361

RESUMEN

One of the main issues in kidney transplantation is the optimal functional preservation of the organ until its transplantation into the appropriate recipient. Despite intensive efforts, the functional preservation period remains limited to hours. During this time, as a result of cellular injury, various proteins, peptides, and other molecules are released by the organ into the preservation medium. In this study, we used proteomic techniques to analyze the protein profiles of preservation solutions in which organs had been preserved prior to their transplantation. Samples were obtained from the preservation solutions of 25 deceased donor kidneys scheduled for transplantation. The protein profiles of the solutions were analyzed using 2D gel electrophoresis/MALDI-TOF and LC-MS/MS. We identified and quantified 206 proteins and peptides belonging to 139 different groups. Of these, 111 proteins groups were belonging to kidney tissues. This study used proteomic techniques to analyze the protein profiles of organ preservation solutions. These findings will contribute to the development of improved preservation solutions to effectively protect organs for transplantation.


Asunto(s)
Riñón/metabolismo , Soluciones Preservantes de Órganos/metabolismo , Cromatografía Liquida/métodos , Trasplante de Riñón/métodos , Preservación de Órganos/métodos , Péptidos/metabolismo , Proteínas/metabolismo , Proteómica/métodos , Espectrometría de Masas en Tándem/métodos
14.
BMC Infect Dis ; 16: 366, 2016 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-27487852

RESUMEN

BACKGROUND: Real-time PCR (qPCR) based methods, such as the Xpert MTB/RIF, are increasingly being used to diagnose tuberculosis (TB). While qualitative methods are adequate for diagnosis, the therapeutic monitoring of TB patients requires quantitative methods currently performed using smear microscopy. The potential use of quantitative molecular measurements for therapeutic monitoring has been investigated but findings have been variable and inconclusive. The lack of an adequate reference method and reference materials is a barrier to understanding the source of such disagreement. Digital PCR (dPCR) offers the potential for an accurate method for quantification of specific DNA sequences in reference materials which can be used to evaluate quantitative molecular methods for TB treatment monitoring. METHODS: To assess a novel approach for the development of quality assurance materials we used dPCR to quantify specific DNA sequences in a range of prototype reference materials and evaluated accuracy between different laboratories and instruments. The materials were then also used to evaluate the quantitative performance of qPCR and Xpert MTB/RIF in eight clinical testing laboratories. RESULTS: dPCR was found to provide results in good agreement with the other methods tested and to be highly reproducible between laboratories without calibration even when using different instruments. When the reference materials were analysed with qPCR and Xpert MTB/RIF by clinical laboratories, all laboratories were able to correctly rank the reference materials according to concentration, however there was a marked difference in the measured magnitude. CONCLUSIONS: TB is a disease where the quantification of the pathogen could lead to better patient management and qPCR methods offer the potential to rapidly perform such analysis. However, our findings suggest that when precisely characterised materials are used to evaluate qPCR methods, the measurement result variation is too high to determine whether molecular quantification of Mycobacterium tuberculosis would provide a clinically useful readout. The methods described in this study provide a means by which the technical performance of quantitative molecular methods can be evaluated independently of clinical variability to improve accuracy of measurement results. These will assist in ultimately increasing the likelihood that such approaches could be used to improve patient management of TB.


Asunto(s)
ADN Bacteriano/aislamiento & purificación , Mycobacterium tuberculosis/genética , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Tuberculosis Pulmonar/diagnóstico , Adulto , Femenino , Humanos , Masculino , Microscopía , Técnicas de Diagnóstico Molecular , Patología Molecular , Sensibilidad y Especificidad
15.
Biomol Detect Quantif ; 8: 15-28, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27335807

RESUMEN

Measurement of RNA can be used to study and monitor a range of infectious and non-communicable diseases, with profiling of multiple gene expression mRNA transcripts being increasingly applied to cancer stratification and prognosis. An international comparison study (Consultative Committee for Amount of Substance (CCQM)-P103.1) was performed in order to evaluate the comparability of measurements of RNA copy number ratio for multiple gene targets between two samples. Six exogenous synthetic targets comprising of External RNA Control Consortium (ERCC) standards were measured alongside transcripts for three endogenous gene targets present in the background of human cell line RNA. The study was carried out under the auspices of the Nucleic Acids (formerly Bioanalysis) Working Group of the CCQM. It was coordinated by LGC (United Kingdom) with the support of National Institute of Standards and Technology (USA) and results were submitted from thirteen National Metrology Institutes and Designated Institutes. The majority of laboratories performed RNA measurements using RT-qPCR, with datasets also being submitted by two laboratories based on reverse transcription digital polymerase chain reaction and one laboratory using a next-generation sequencing method. In RT-qPCR analysis, the RNA copy number ratios between the two samples were quantified using either a standard curve or a relative quantification approach. In general, good agreement was observed between the reported results of ERCC RNA copy number ratio measurements. Measurements of the RNA copy number ratios for endogenous genes between the two samples were also consistent between the majority of laboratories. Some differences in the reported values and confidence intervals ('measurement uncertainties') were noted which may be attributable to choice of measurement method or quantification approach. This highlights the need for standardised practices for the calculation of fold change ratios and uncertainties in the area of gene expression profiling.

17.
Talanta ; 149: 244-249, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26717837

RESUMEN

This work describes the single-use electrochemical DNA biosensor technology developed for voltammetric detection of sequence selective DNA hybridization related to important human and veterinary pathogen; Toxoplasma gondii. In the principle of electrochemical label-free detection assay, the duplex of DNA hybrid formation was detected by measuring guanine oxidation signal occured in the presence of DNA hybridization. The biosensor design consisted of the immobilization of an inosine-modified (guanine-free) probe onto the surface of pencil graphite electrode (PGE), and the detection of the duplex formation in connection with the differential pulse voltammetry(DPV) by measuring the guanine signal. Toxoplasma gondii capture probe was firstly immobilized onto the surface of the activated PGE by wet adsorption. The extent of hybridization at PGE surface between the probe and the target was then determined by measuring the guanine signal observed at +1.0V. The electrochemical monitoring of optimum DNA hybridization has been performed in the target concentration of 40µg/mL in 50min of hybridization time. The specificity of the electrochemical biosensor was then tested using non-complementary, or mismatch short DNA sequences. Under the optimum conditions, the guanine oxidation signal indicating full hybridization was measured in various target concentration from 0.5 to 25µg/mL and a detection limit was found to be 1.78µg/mL. This single-use biosensor platform was successfully applied for the voltammetric detection of DNA hybridization related to Toxoplasma gondii in PCR amplicons.


Asunto(s)
Técnicas Biosensibles , Toxoplasma/genética , ADN Protozoario , Técnicas Electroquímicas , Guanina , Hibridación de Ácido Nucleico , Reacción en Cadena de la Polimerasa
18.
Anal Chem ; 88(24): 12169-12176, 2016 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-28193036

RESUMEN

Enumeration-based determination of DNA copy-concentration was assessed through an international comparison among national metrology institutes (NMIs) and designated institutes (DIs). Enumeration-based quantification does not require a calibration standard thereby providing a route to "absolute quantification", which offers the potential for reliable value assignments of DNA reference materials, and International System of Units (SI) traceability to copy number 1 through accurate counting. In this study, 2 enumeration-based methods, flow cytometric (FCM) counting and the digital polymerase chain reaction (dPCR), were compared to quantify a solution of the pBR322 plasmid at a concentration of several thousand copies per microliter. In addition, 2 orthogonal chemical-analysis methods based on nucleotide quantification, isotope-dilution mass spectrometry (IDMS) and capillary electrophoresis (CE) were applied to quantify a more concentrated solution of the plasmid. Although 9 dPCR results from 8 laboratories showed some dispersion (relative standard deviation [RSD] = 11.8%), their means were closely aligned with those of the FCM-based counting method and the orthogonal chemical-analysis methods, corrected for gravimetric dilution factors. Using the means of dPCR results, the RSD of all 4 methods was 1.8%, which strongly supported the validity of the recent enumeration approaches. Despite a good overall agreement, the individual dPCR results were not sufficiently covered by the reported measurement uncertainties. These findings suggest that some laboratories may not have considered all factors contributing to the measurement uncertainty of dPCR, and further investigation of this possibility is warranted.


Asunto(s)
ADN/análisis , Citometría de Flujo/métodos , Plásmidos/análisis , Reacción en Cadena de la Polimerasa/métodos , Electroforesis Capilar , Espectrometría de Masas , Nucleótidos/análisis
19.
Appl Biochem Biotechnol ; 178(4): 849-64, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26541162

RESUMEN

Tuberculosis (TB) remains to be a major global health problem, with about 9 million new cases and 1.4 million deaths in 2011. For the control of tuberculosis as well as other infectious diseases, WHO recommended "ASSURED" (Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free, and Deliverable to the end user) diagnostic tools that can easily be maintained and used in developing countries. Aptamers are promising tools for developing point-of-care diagnostic assays for TB. In this study, ssDNA aptamers that recognize Mycobacterium tuberculosis H37Ra were selected by systematic evolution of ligands by exponential enrichment (SELEX). For this purpose, two different selection protocols, ultrafiltration and centrifugation, were applied. A total of 21 TB specific aptamers were selected. These aptamers exhibited "G-rich" regions on the 3' terminus of the aptamers, including a motif of "TGGGG," "GTGG," or "CTGG." Binding capability of selected aptamers were investigated by quantitative PCR and Mtb36 DNA aptamer was found the most specific aptamer to M. tuberculosis H37Ra. The dissociation constant (K d) of Mtb36 aptamer was calculated as 5.09 ± 1.43 nM in 95% confidence interval. Relative binding ratio of Mtb36 aptamer to M. tuberculosis H37Ra over Mycobacterium bovis and Escherichia coli was also determined about 4 times and 70 times more, respectively. Mtb36 aptamer is highly selective for M. tuberculosis, and it can be used in an aptamer-based biosensor for the detection of M. tuberculosis.


Asunto(s)
Aptámeros de Nucleótidos/química , Mycobacterium tuberculosis/aislamiento & purificación , Humanos , Técnica SELEX de Producción de Aptámeros , Tuberculosis/diagnóstico
20.
Can J Physiol Pharmacol ; 93(8): 727-35, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26243022

RESUMEN

This study investigated the preventive role of resveratrol in cisplatin-induced nephrotoxicity. The study used groups of New Zealand rabbits that were treated as follows: group C (cisplatin treated), group R (resveratrol treated), group R+C (resveratrol + cisplatin treatment), and group E (control group). Kidney levels of glutathione were significantly lower in group C than in groups E and R, whereas glutathione levels in group R+C were found to be similar to the control values. Malondialdehyde levels in group C were significantly higher than in groups E and R. However, malondialdehyde levels in group R+C were similar to group E. Kidney levels of nitric oxide were significantly higher in the cisplatin group than in the control, whereas nitric oxide levels were at basal values in group R+C. Cisplatin treatment significantly reduced kidney levels of glutathione peroxidase, superoxide dismutase, and catalase activity compared with those of group E, whereas resveratrol treatment significantly increased levels of glutathione peroxidase, superoxide dismutase, and catalase activity in group R+C. However, cisplatin injection did not affect mRNA levels of glutathione peroxidase, superoxide dismutase, or catalase enzymes. Histopathological and immunohistochemical analyses indicated that cisplatin caused kidney damage, which was mostly prevented by resveratrol treatment. In conclusion, resveratrol ameliorates cisplatin-induced oxidative injury in the kidney of rabbit.


Asunto(s)
Antioxidantes/farmacología , Cisplatino , Enfermedades Renales/prevención & control , Riñón/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Estilbenos/farmacología , Animales , Catalasa/genética , Catalasa/metabolismo , Citoprotección , Modelos Animales de Enfermedad , Glutatión/metabolismo , Glutatión Peroxidasa/genética , Glutatión Peroxidasa/metabolismo , Riñón/metabolismo , Riñón/patología , Enfermedades Renales/inducido químicamente , Enfermedades Renales/genética , Enfermedades Renales/metabolismo , Enfermedades Renales/patología , Masculino , Malondialdehído/metabolismo , Óxido Nítrico/metabolismo , ARN Mensajero/metabolismo , Conejos , Resveratrol , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo
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