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1.
Eur J Orthop Surg Traumatol ; 34(3): 1581-1595, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38363346

RESUMEN

PURPOSE: There is a lack of consensus regarding the best type of reconstruction of the proximal femur following bone tumor resection. The objective of this study was to analyze the complication risks, implant survival, and functional outcomes following modular prosthesis (MP) and allograft-prosthesis composite (APC) reconstruction of the proximal femur after primary bone tumor resections. METHODS: We performed a search in the PubMed and Scopus libraries, obtaining 1 843 studies. We included studies reporting functional outcomes, complications, and implant survival of proximal femur reconstruction with MP or APC following primary bone tumor resection with a 2-year minimum follow-up. We excluded studies analyzing metastatic patients or studies with pooled data in which it was impossible to separate the data of patients with primary bone tumors from those with bone metastases. RESULTS: We analyzed 18 studies (483 patients) reporting on 234 (48%) patients with MP reconstruction and 249 (52%) patients with APC reconstruction. The risk of complications was similar in patients with MP reconstruction (29%; 95% CI [0.11; 0.47]) and APC reconstruction (36%; 95% CI [0.24; 0.47]) (p = 0.48). Implant survival following MP reconstruction ranged from 81 to 86% at 5 years, 75 to 86% at 10 years, and 82% at 15 years. Implant survival following APC reconstruction ranged from 86 to 100% at 5 years and 86% at 10 years, and 86% at 15 years. Functional outcomes following MP reconstruction and APC reconstruction ranged from 24.0 to 28.3 and from 21.9 to 27.8, respectively. CONCLUSION: Patients with primary bone tumor of the proximal femur who underwent MP or APC reconstruction seem to have similar complication risks, implant survival, and functional outcomes.


Asunto(s)
Neoplasias Femorales , Humanos , Neoplasias Femorales/cirugía , Neoplasias Femorales/secundario , Trasplante Óseo/métodos , Trasplante Óseo/efectos adversos , Fémur/cirugía , Neoplasias Óseas/cirugía , Complicaciones Posoperatorias/etiología , Falla de Prótesis , Aloinjertos , Procedimientos de Cirugía Plástica/métodos , Procedimientos de Cirugía Plástica/efectos adversos , Resultado del Tratamiento , Diseño de Prótesis
2.
Dermatol Ther ; 33(2): e13250, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32022968

RESUMEN

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent nonmelanoma skin cancer (NMSC). The majority of in situ cSCC [cSCC (Tis)] can be cured surgically, while local advanced and metastatic ones require other treatments, but there are no therapies approved by U.S. Food and Drug Administration (FDA). Available treatments for these stages included radiotherapy, chemotherapy as cisplatin, but responses to these treatments are usually of short duration. Programmed death-1 (PD-1) inhibitors (pembrolizumab, nivolumab, and cemiplimab) are an innovative immunologic treatment that now has been shown to be useful for the treatment of advanced cSCC. Nowadays, data about the response rate with the use of PD-1 inhibitors in cSCC are still few and, especially, the duration of the response after the start of treatment is short. Moreover, the number of cases is too small to express the beneficial effects of these treatments, although most data reported in the literature show quite good response rates. This review focused on some of the studies and associated results through an interesting research on search engines of all the cases about these systemic drugs, analyzing effects and side effects, and the research has been conducted considering published cases since March 2016 to October 2019.


Asunto(s)
Carcinoma de Células Escamosas , Neoplasias Cutáneas , Carcinoma de Células Escamosas/tratamiento farmacológico , Humanos , Nivolumab , Receptor de Muerte Celular Programada 1 , Neoplasias Cutáneas/tratamiento farmacológico , Estados Unidos
3.
Analyst ; 142(18): 3441-3450, 2017 Sep 08.
Artículo en Inglés | MEDLINE | ID: mdl-28828442

RESUMEN

We report on an optomagnetic technique optimised for real-time molecular detection of Dengue fever virus under ideal as well as non-ideal laboratory conditions using two different detection approaches. The first approach is based on the detection of the hydrodynamic volume of streptavidin coated magnetic nanoparticles attached to biotinylated LAMP amplicons. We demonstrate detection of sub-femtomolar Dengue DNA target concentrations in the ideal contamination-free lab environment within 20 min. The second detection approach is based on sequence-specific binding of functionalised magnetic nanoparticles to loops of LAMP amplicons. Melting studies reveal that true positive and spurious amplicons have different melting points and this allows us to discriminate between them. This is found to be in a good agreement with subsequent studies on real-time sequence-specific discrimination of LAMP amplicons. The specific binding causes clustering of magnetic nanoparticles via binding to multiple sites (loops) emerging in the elongation phase of LAMP. Formation of nanoclusters is monitored via the depletion of the optomagnetic signal due to free nanoparticles. After sequence-specific validation, we claim detection of down to 100 fM of Dengue target after 20 min of LAMP with a contamination background.


Asunto(s)
ADN Viral/análisis , Virus del Dengue/aislamiento & purificación , Técnicas de Amplificación de Ácido Nucleico , Nanopartículas de Magnetita , Sensibilidad y Especificidad , Serogrupo , Estreptavidina
4.
Biotechnol Bioeng ; 113(9): 1942-52, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-26888596

RESUMEN

The kinase mTOR operates in two cellular complexes, mTORC1 and mTORC2. mTORC1 adjusts metabolic activity according to external growth conditions and nutrients availability. When conditions are prosperous, mTOR facilitates protein and lipid biosyntheses and inhibits autophagy, while under metabolic constraints, however, its attenuation induces a catabolic program, energy preservation and autophagy. CHO is a key cell line for manufacturing of biologics owing to its remarkable ability to grow to high densities and maintain protein production and secretion for extended times. While high mTOR activity has been associated with high productivity in CHO cells, its inhibition by rapamycin has also been documented to augment productivity via promotion of viability. Here using CRISPR/Cas9 editing we engineered CHO cells to enforce high mTORC1 activity by knocking-out TSC2, a major mTOR inhibitory protein, or PTEN, a phosphatase that attenuates the PI3K/AKT/mTOR pathway. Only TSC2-deleted cells exhibited a constitutive activation of mTORC1 under fed batch conditions. Cells grew larger in size, synthesized more proteins and displayed an over twofold elevation in their specific productivity. While peak viable cell density was compromised, overall titers increased to an extent dependent upon the parental clone. Our data underscore manipulation of TSC as a strategy to improve performance of CHO cell in bioreactors. Biotechnol. Bioeng. 2016;113: 1942-1952. © 2016 Wiley Periodicals, Inc.


Asunto(s)
Anticuerpos/metabolismo , Reactores Biológicos , Técnicas de Inactivación de Genes/métodos , Ingeniería Metabólica/métodos , Proteínas Supresoras de Tumor/genética , Animales , Anticuerpos/análisis , Anticuerpos/química , Anticuerpos/genética , Células CHO , Sistemas CRISPR-Cas/genética , Cricetinae , Cricetulus , Diana Mecanicista del Complejo 1 de la Rapamicina , Complejos Multiproteicos/genética , Complejos Multiproteicos/metabolismo , Fosfohidrolasa PTEN/genética , Transducción de Señal , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo , Proteína 2 del Complejo de la Esclerosis Tuberosa
6.
Small ; 10(14): 2877-82, 2014 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-24616417

RESUMEN

For the first time DNA coils formed by rolling circle amplification are quantified on-chip by Brownian relaxation measurements on magnetic nanobeads using a magnetoresistive sensor. No external magnetic fields are required besides the magnetic field arising from the current through the sensor, which makes the setup very compact. Limits of detection down to 500 Bacillus globigii spores and 2 pM of Vibrio cholerae are demonstrated, which are on the same order of magnitude or lower than those achieved previously using a commercial macro-scale AC susceptometer. The chip-based readout is an important step towards the realization of field tests based on rolling circle amplification molecular analyses.


Asunto(s)
Bacillus/química , ADN Bacteriano/análisis , ADN Circular/análisis , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Vibrio cholerae/química , Bacillus/genética , Técnicas Biosensibles/métodos , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Circular/química , ADN Circular/genética , Nanopartículas de Magnetita , Técnicas Analíticas Microfluídicas/métodos , Técnicas de Amplificación de Ácido Nucleico , Esporas Bacterianas/química , Esporas Bacterianas/genética , Vibrio cholerae/genética
7.
Bioengineering (Basel) ; 9(4)2022 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-35447733

RESUMEN

Improving productivity to reduce the cost of biologics manufacturing and ensure that therapeutics can reach more patients remains a major challenge faced by the biopharmaceutical industry. Chinese hamster ovary (CHO) cell lines are commonly prepared for biomanufacturing by single cell cloning post-transfection and recovery, followed by lead clone screening, generation of a research cell bank (RCB), cell culture process development, and manufacturing of a master cell bank (MCB) to be used in early phase clinical manufacturing. In this study, it was found that an additional round of cloning and clone selection from an established monoclonal RCB or MCB (i.e., re-cloning) significantly improved titer for multiple late phase monoclonal antibody upstream processes. Quality attributes remained comparable between the processes using the parental clones and the re-clones. For two CHO cells expressing different antibodies, the re-clone performance was successfully scaled up at 500-L or at 2000-L bioreactor scales, demonstrating for the first time that the re-clone is suitable for late phase and commercial manufacturing processes for improvement of titer while maintaining comparable product quality to the early phase process.

8.
Skin Appendage Disord ; 7(5): 339-345, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34604320

RESUMEN

Neoplastic alopecia (NA) is defined as an organized hair loss in single or multiple areas of the scalp caused by a primary tumor that has metastasized to the skin of the scalp. Due to its localization and clinical appearance, NA should be placed in differential diagnosis with alopecia areata or other entities. To date, pathognomonic dermoscopic criteria of NA have not yet been described: the absence of classical criteria of other scalp diseases in addition to a major neovascularization with on-focus arborizing vessels and erosions or ulcerations may help the clinician to suspect a diagnosis of secondary alopecia. Dermatologists should pay more attention to these rare forms of secondarism because in exceptional cases, a simple alopecia of the scalp can hide a new, relapsing or metastatic neoplasia.

9.
G Ital Dermatol Venereol ; 155(2): 220-222, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31210468

RESUMEN

Lyme disease is a tick-borne illness, which is typically caused by Borrelia Burgdoferi. Over time, a typical Borreliosis skin reaction takes shape, i.e. the formation of an annular erythema that tends to expand centrifugally with erythematous edges whose diameter can reach up to 20 cm. The symptoms of Lyme disease are not only cutaneous but there may be a systemic involvement. Obviously, this disease can also affect pregnant women and for this reason this review aims to summarize the main ways of treatment to avoid worsening of the clinical condition in the mother and an eventual, albeit rare, involvement of the fetus.


Asunto(s)
Antibacterianos/uso terapéutico , Enfermedad de Lyme/tratamiento farmacológico , Complicaciones Infecciosas del Embarazo/tratamiento farmacológico , Femenino , Humanos , Embarazo
10.
Int J Dermatol ; 59(6): 677-684, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32012240

RESUMEN

Actinic keratosis (AK) is a very common skin disease caused by chronic sun damage, which in 75% of cases arises on chronically sun-exposed areas, such as face, scalp, neck, hands, and forearms. AKs must be considered an early squamous cell carcinoma (SCC) for their probable progression into invasive SCC. For this reason, all AK should be treated, and clinical follow-up is recommended. The aims of treatment are: (i) to clinically eradicate evident and subclinical lesions, (ii) to prevent their evolution into SCC, and (iii) to reduce the number of relapses. Among available treatments, it is possible to distinguish lesion-directed therapies and field-directed therapies. Lesion-directed treatments include: (i) cryotherapy; (ii) laser therapy; (iii) surgery; and (iv) curettage. Whereas, field-directed treatments are: (i) 5-fluorouracil (5-FU); (ii) diclofenac 3% gel; (iii) chemical peeling; (iv) imiquimod; and (v) photodynamic therapy (PDT). Prevention plays an important role in the treatment of AKs, and it is based on the continuous use of sunscreen and protective clothing. This review shows different types of available treatments and describes the characteristics and benefits of each medication, underlining the best choice.


Asunto(s)
Carcinoma de Células Escamosas/prevención & control , Queratosis Actínica/terapia , Neoplasias Cutáneas/prevención & control , Cuidados Posteriores/normas , Carcinoma de Células Escamosas/etiología , Carcinoma de Células Escamosas/patología , Quimioexfoliación/métodos , Quimioexfoliación/normas , Crioterapia/métodos , Crioterapia/normas , Legrado/métodos , Legrado/normas , Dermoscopía , Diclofenaco/administración & dosificación , Progresión de la Enfermedad , Fluorouracilo/administración & dosificación , Humanos , Imiquimod/administración & dosificación , Queratosis Actínica/diagnóstico , Queratosis Actínica/etiología , Queratosis Actínica/patología , Terapia por Láser/métodos , Terapia por Láser/normas , Fotoquimioterapia/métodos , Fotoquimioterapia/normas , Guías de Práctica Clínica como Asunto , Ropa de Protección , Piel/diagnóstico por imagen , Piel/efectos de los fármacos , Piel/efectos de la radiación , Neoplasias Cutáneas/etiología , Neoplasias Cutáneas/patología , Luz Solar/efectos adversos , Protectores Solares/administración & dosificación
11.
Dermatol Pract Concept ; 10(2): e2020028, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32363091

RESUMEN

The association of melanoma with a preexisting nevus is still a debated subject. Histopathological data support an associated nevus in approximately 30% of all excised melanomas. The annual risk of an individual melanocytic nevus becoming malignant is extremely low and has been estimated to be approximately 0.0005% (or less than 1 in 200,000) before the age of 40 years, to 0.003% (1 in 33,000) in patients older than 60 years. Current understanding, based on the noticeable, small, truly congenital nevi and nevi acquired early in life, is that the first develops before puberty, presents with a dermoscopic globular pattern, and persists for the lifetime, becoming later a dermal nevus in the adult. In contrast, acquired melanocytic nevi develop mostly at puberty and usually undergo spontaneous involution after the fifth decade of life. The purpose of this review is to analyze the data of the literature and to propose, on the basis of epidemiological and clinical-dermoscopic characteristics, a new model of melanogenesis of nevus-associated melanoma.

12.
Biosens Bioelectron ; 124-125: 136-142, 2019 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-30366258

RESUMEN

Aberrant hypermethylation of CpG islands in the promoter region of tumor suppressor genes is a promising biomarker for early cancer detection. This methylation status is reflected in the methylation pattern of ctDNA shed from the primary tumor; however, to realize the full clinical utility of ctDNA methylation detection via liquid biopsy for early cancer diagnosis, improvements in the sensitivity and multiplexability of existing technologies must be improved. Additionally, the assay must be cheap and easy to perform in a clinical setting. We report the integration of methylation specific PCR (MSP) to melt curve analysis on giant magnetoresistive (GMR) biosensors to greatly enhance the sensitivity of our DNA hybridization assay for methylation detection. Our GMR sensor is functionalized with synthetic DNA probes that target methylated or unmethylated CpG sites in the MSP amplicon, and measures the difference in melting temperature (Tm) between the two probes (ΔTm), giving an analytical limit of detection down to 0.1% methylated DNA in solution. Additionally, linear regression of ΔTm's for serial dilutions of methylated:unmethylated mixtures allows for quantification of methylation percentage, which could have diagnostic and prognostic utility. Lastly, we performed multiplexed MSP on two different genes, and show the ability of our GMR assay to resolve this mixture, despite their amplicons' overlapping Tm's in standard EvaGreen melt analysis. The multiplexing ability of our assay and its enhanced sensitivity, without necessitating deep sequencing, represent important steps toward realizing an assay for the detection of methylated ctDNA in plasma for early cancer detection in a clinical setting.


Asunto(s)
Técnicas Biosensibles , Metilación de ADN/genética , Melanoma/genética , Islas de CpG/genética , Humanos , Melanoma/diagnóstico , Melanoma/patología , Regiones Promotoras Genéticas , Proteínas Supresoras de Tumor/genética
13.
Biosens Bioelectron ; 142: 111485, 2019 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-31301578

RESUMEN

Rolling circle amplification (RCA) combined with padlock probe recognition of a DNA target is attractive for on-chip nucleic acid testing due to its high specificity and isothermal reaction conditions. However, the integration of RCA on an automated chip platform is challenging due to the different reagents needed for the reaction steps and the temperature sensitivity of the phi29 polymerase. Here, we describe the integration of an RCA assay on a single-use polymer chip platform where magnetic microbeads are used as solid support to transport the DNA target between three connected reaction chambers for (i) padlock probe annealing and ligation, (ii) RCA, and (iii) optomagnetic detection of RCA products. The three chambers were loaded with reagents by sequential filling combined with passive microfluidic structures. After loading, the on-chip assay steps were automated. For an assay in which all steps but the padlock probe annealing on the target were performed on-chip, we found a limit of detection (LOD) for a synthetic influenza target of 2 pM after 45 min of RCA, which is comparable to the corresponding laboratory assay. The entire assay, including padlock probe annealing, could be performed on-chip with an LOD of 20 pM after 45 min of RCA. This LOD can likely be reduced by further optimizing the microbead mixing. The results present important steps towards the integration and automation of RCA and potentially also other complex multi-step assays on a single-use polymer chip for molecular analysis.


Asunto(s)
Técnicas Biosensibles/instrumentación , ADN/análisis , Dispositivos Laboratorio en un Chip , Técnicas de Amplificación de Ácido Nucleico/instrumentación , ADN/genética , Diseño de Equipo , Límite de Detección , Magnetismo/instrumentación , Análisis de Secuencia por Matrices de Oligonucleótidos/instrumentación
14.
Biosens Bioelectron ; 130: 338-343, 2019 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-30269961

RESUMEN

Gene expression analysis at the point-of-care is important for rapid disease diagnosis, but traditional techniques are limited by multiplexing capabilities, bulky equipment, and cost. We present a gene expression analysis platform using a giant magnetoresistive (GMR) biosensor array, which allows multiplexed transcript detection and quantification through cost-effective magnetic detection. In this work, we have characterized the sensitivity, dynamic range, and quantification accuracy of Polymerase chain reaction (PCR)-amplified complementary DNA (cDNA) on the GMR for the reference gene GAPDH. A synthetic GAPDH single-stranded DNA (ssDNA) standard was used to calibrate the detection, and ssDNA dilutions were qPCR-amplified to obtain a standard curve. We demonstrate that the GMR platform provides a dynamic range of 4 orders of magnitude and a limit of detection of 1 pM and 0.1 pM respectively for 15 and 18-cycle amplified synthetic GAPDH PCR products. The quantitative results of GMR analysis of cell-line RNA were confirmed by qPCR.


Asunto(s)
Biomarcadores/química , Técnicas Biosensibles , ADN Complementario/genética , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/aislamiento & purificación , ADN Complementario/química , ADN de Cadena Simple/química , Perfilación de la Expresión Génica/métodos , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/química , Humanos , Magnetismo , Sistemas de Atención de Punto
15.
Artículo en Inglés | MEDLINE | ID: mdl-31233175

RESUMEN

The Koebner phenomenon is well described and well known in clinical practice. Sometimes it can take on a linear appearance, the diagnosis of which can be facilitated by the use of dermatoscopy. In this case, we present a comparison between a linear Koebner phenomenon on light and dark skin, reporting the salient dermatoscopic characteristics and relating them to histopathology.


Asunto(s)
Liquen Plano/diagnóstico , Liquen Plano/fisiopatología , Pigmentación de la Piel , Piel/patología , Humanos
16.
Acta Dermatovenerol Alp Pannonica Adriat ; 28(4): 185-186, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31855275

RESUMEN

The cutaneous adverse effects of gemcitabine include allergic skin rash frequently associated with pruritus, alopecia, sweating, dermatitis with boils, and ulcerations. We report the case of a patient that developed inflammation of seborrheic keratoses after gemcitabine treatment.


Asunto(s)
Antimetabolitos Antineoplásicos/efectos adversos , Desoxicitidina/análogos & derivados , Erupciones por Medicamentos/etiología , Queratosis Seborreica/inducido químicamente , Adenocarcinoma del Pulmón/tratamiento farmacológico , Anciano , Antimetabolitos Antineoplásicos/uso terapéutico , Desoxicitidina/efectos adversos , Desoxicitidina/uso terapéutico , Femenino , Humanos , Gemcitabina
17.
Expert Rev Anticancer Ther ; 18(10): 1007-1012, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-30079779

RESUMEN

INTRODUCTION: Cutaneous melanoma is the sixth most common malignant cancer in the USA. Among different subtypes of melanoma, nodular melanoma (NM) accounts about 14% of all cases but is responsible for more than 40% of melanoma deaths. Early diagnosis is the best method to improve melanoma prognosis. Unfortunately, early diagnosis of NM is particularly challenging given that patients often lack identifiable risk factors such as many moles or freckles. Moreover, early NM may mimic a range of benign skin lesions that are not routinely excised or biopsied in every day practice. For this reason, specific clinical and skin imaging clues have been proposed to improve early detection of NM. Areas covered: The review discusses about the noninvasive tools to diagnose thin melanoma, particularly NM. Expert commentary: Currently, dermatologists present a wide opportunity of diagnostic tools. Current data suggest that the early diagnosis of NM is a major challenge as the majority of early NM are symmetric, roundish, and lack specific pattern. Another promising strategy is based on recent data suggesting that artificial intelligence based on deep convolutional neural networking is able to outperform average dermatologist. Further research is necessary to validate the performance of this method in the real world and in the clinical setting.


Asunto(s)
Melanoma/diagnóstico , Enfermedades de la Piel/diagnóstico , Neoplasias Cutáneas/diagnóstico , Dermatólogos/organización & administración , Dermatología/métodos , Detección Precoz del Cáncer/métodos , Humanos , Melanoma/patología , Pronóstico , Enfermedades de la Piel/patología , Neoplasias Cutáneas/patología
18.
Lab Chip ; 17(13): 2256-2263, 2017 06 27.
Artículo en Inglés | MEDLINE | ID: mdl-28593203

RESUMEN

We present a microfluidic system and its use to measure DNA denaturation curves by varying the temperature or salt (Na+) concentration. The readout is based on real-time measurements of DNA hybridization using magnetoresistive sensors and magnetic nanoparticles (MNPs) as labels. We report the first melting curves of DNA hybrids measured as a function of continuously decreasing salt concentration at fixed temperature and compare them to the corresponding curves obtained vs. temperature at fixed salt concentration. The magnetoresistive sensor platform provided reliable results under varying temperature as well as salt concentration. The salt concentration melting curves were found to be more reliable than temperature melting curves. We performed a two-dimensional mapping of the melting profiles of a target to probes targeting its wild type (WT) and mutant type (MT) variants in the temperature-salt concentration plane. This map clearly showed a region of optimum ability to differentiate between the two variants. We finally demonstrated single nucleotide polymorphysm (SNP) genotyping using both denaturation methods on both separate sensors but also using a differential measurement on a single sensor. The results demonstrate that concentration melting provides an attractive alternative to temperature melting in on-chip DNA denaturation experiments and further show that the magnetoresistive platform is attractive due to its low cross-sensitivity to temperature and liquid composition.


Asunto(s)
Técnicas Biosensibles/métodos , Nanopartículas de Magnetita/química , Desnaturalización de Ácido Nucleico , Cloruro de Sodio/química , Técnicas Biosensibles/instrumentación , ADN/análisis , ADN/química , Diseño de Equipo , Humanos , Dispositivos Laboratorio en un Chip , Temperatura , Globinas beta/genética
19.
Biosens Bioelectron ; 93: 155-160, 2017 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-27650710

RESUMEN

Microarrays and other surface-based nucleic acid detection schemes rely on the hybridization of the target to surface-bound detection probes. We present the first comparison of two strategies to detect DNA using a giant magnetoresistive (GMR) biosensor platform starting from an initially double-stranded DNA target. The target strand of interest is biotinylated and detected by the GMR sensor by linking streptavidin magnetic nanoparticles (MNPs) to the sensor surface. The sensor platform has a dynamic detection range from 40pM to 40nM with highly reproducible results and is used to monitor real-time binding signals. The first strategy, using off-chip heat denaturation followed by sequential on-chip incubation of the nucleic acids and MNPs, produces a signal that stabilizes quickly but the signal magnitude is reduced due to competitive rehybridization of the target in solution. The second strategy, using magnetic capture of the double-stranded product followed by denaturing, produces a higher signal but the signal increase is limited by diffusion of the MNPs. Our results show that both strategies give highly reproducible results but that the signal obtained using magnetic capture is higher and insensitive to rehybridization.


Asunto(s)
Técnicas Biosensibles/métodos , ADN/aislamiento & purificación , Fenómenos Magnéticos , Nanopartículas de Magnetita/química , ADN/química , Hibridación de Ácido Nucleico/métodos , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Reacción en Cadena de la Polimerasa , Estreptavidina/química
20.
ACS Nano ; 11(9): 8864-8870, 2017 09 26.
Artículo en Inglés | MEDLINE | ID: mdl-28832112

RESUMEN

Epigenetic modifications, in particular DNA methylation, are gaining increasing interest as complementary information to DNA mutations for cancer diagnostics and prognostics. We introduce a method to simultaneously profile DNA mutation and methylation events for an array of sites with single site specificity. Genomic (mutation) or bisulphite-treated (methylation) DNA is amplified using nondiscriminatory primers, and the amplicons are then hybridized to a giant magnetoresistive (GMR) biosensor array followed by melting curve measurements. The GMR biosensor platform offers scalable multiplexed detection of DNA hybridization, which is insensitive to temperature variation. The melting curve approach further enhances the assay specificity and tolerance to variations in probe length. We demonstrate the utility of this method by simultaneously profiling five mutation and four methylation sites in human melanoma cell lines. The method correctly identified all mutation and methylation events and further provided quantitative assessment of methylation density validated by bisulphite pyrosequencing.


Asunto(s)
Técnicas Biosensibles/instrumentación , Análisis Mutacional de ADN/instrumentación , ADN/genética , Melanoma/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/instrumentación , Línea Celular Tumoral , Metilación de ADN , Diseño de Equipo , Humanos , Mutación , Desnaturalización de Ácido Nucleico
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