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【Objective】 To investigate the effect of ssDNA aptamer of RhD blood group antigen on erythrocyte toxicity. 【Methods】 Two full-length ssDNA aptamers(82 bp) of RhD blood group antigen were obtained by gene synthesis.Five samples of whole blood with EDTA anticoagulant were collected to prepare red blood cell suspensions (4×107/mL), which were split into 10 tubes(100 μL/tube), corresponding to 5 experimental groups and 5 controls.Two monospecific full-length ssDNA sequences (100 pmol/μL, 5μL each) were added into the experimental group, while the same amount of normal saline into the control.After treatment, the experimental group and the control were incubated for 60 min at 37℃.After washing, they were suspended in LISS solution and stored at 4℃.The experimental group and the control were set according to different time point during storage (1 h, 1 d, 3 d, 10 d and 17 d), with 5 tubes in each group.For erythrocytes in LISS suspension at different storage time, Annexin V labeled with FITC was used as a probe to label the phosphatidylserine (PS) content and Fluo-4 to label Ca2+ .The eversion of PS and the change of Ca2+ concentration in red blood cells in LISS suspensions were determined by flow cytometry. 【Results】 After incubation, all groups were examined under the light microscope.No agglutination occurred in the experimental group, while agglutination occurred in the control.Flow cytometry showed that the number of Annexin V-FITC staining cells of suspended erythrocytes at the same storage time-point was similar between the experimental group and the control, with no significant differences.In the experimental group, apoptosis rate of Annexin V cells at 10-day storage(6.06±1.38) was significantly higher than that at 1-hour storage(P<0.05), so as at 17-day storage(7.77±1.23) than 1-hour, 1-day and 3-day storage(P<0.05). The apoptosis rate of Fluo-4 AM cell in suspended RBCs at the same storage time-point was similar between the two groups(P>0.05). In the experimental group, the apoptosis rate of Fluo-4 AM cell at the 3-day, 10-day and 17-day storage was 20.84±4.16, 22.35±3.37 and 27.06±2.81, respectively(P<0.05). 【Conclusion】 ssDNA aptamer was not found to have any cytotoxic effects on red blood cells, and RhD ssDNA aptamer may be used as a material for the detection and preparation of universal blood.
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Introducción: La prueba de anticuerpos antinucleares es una poderosa herramienta en el diagnóstico de las enfermedades reumáticas. Los anticuerpos antinucleares se determinan en el laboratorio por un algoritmo o secuencia que se inicia con prueba de cribado y sigue con la identificación de las especificidades antinucleares más comunes. Pero, ¿cómo interpretar los resultados discordantes entre los dos niveles de estudio de anticuerpos antinucleares? Objetivo: Determinar las especificidades antinucleares menos frecuentes en pacientes positivos de cribado de ANA y negativos de las especificidades más comunes. Métodos: Estudio prospectivo de 88 pacientes consecutivos remitidos para la detección rutinaria de ANA con resultado positivo de cribado por ensayo inmuno-adsorbente ligado a enzima (ELISA) pero negativo de anticuerpos anti-ADN de doble cadena (dc, IgG) y anti-antígenos nucleares extraíbles comunes (ENAc). Las muestras séricas correspondientes fueron evaluadas por inmunofluorescencia indirecta sobre células de carcinoma epidermoide laríngeo humano (IFI-HEp-2) y por ELISA para la detección individual de ANA específicos. Resultados: La prueba de ANA por IFI/HEp-2 resultó positiva en 56/88 (63,6 por ciento) y las especificidades antinucleares se detectaron en 57/88 (64,8 por ciento) muestras, en el orden decreciente de Anti-Nucs: 16/88 (18,2 por ciento); anti-centrómero (CENP-B): 15/88 (17,0 por ciento); -histona: 15/88 (17 por ciento); -PM/Scl: 13/88 (14,8 por ciento); -ADNsc: 11/88 (12,5 por ciento) y -ENAc individuales: 8/88 (9,1 por ciento). La sensibilidad de la IFI-HEp-2 para las especificidades antinucleares fue de 0,83 (IC95 por ciento: 0,72-0,93). De los pacientes negativos de subserología (26/31), 83,9 por ciento no tenían antecedentes de enfermedad reumática asociada a ANA. Conclusiones: La mayoría de los pacientes con resultados discordantes entre el primer y segundo nivel de ANA fueron positivos de especificidades antinucleares menos comunes, pero de reconocido valor diagnóstico(AU)
Introduction: The antinuclear antibody test is a powerful tool for diagnosing rheumatic diseases. Antinuclear antibodies are determined in the laboratory by an algorithm or sequence that starts with a screening test and continues with the identification of the most common antinuclear specificities. But how to interpret the discordant results between the two levels of study of antinuclear antibodies? Objective: To determine the less frequent antinuclear specificities in positive patients of ANA screening and negative of the most common specificities. Methods: A prospective study was done on 88 consecutive patients referred for the routine ANA screening with a positive result of screening by enzyme-linked immunosorbent assay (ELISA) but negative for anti-double-stranded DNA (dc, IgG) and common extractable anti-nuclear antigens (ENAc). The corresponding serum samples were evaluated by indirect immunofluorescence on human laryngeal epidermoid carcinoma cells (IFI-HEp-2) and by ELISA for the individual detection of specific ANA. Results: The ANA test by IFI / HEp-2 was positive in 56/88 (63.6 percent) and the antinuclear specificities were detected in 57/88 (64.8 percent) samples, in decreasing Anti-Nucs order: 16/88 (18.2 percent); anti-centromere (CENP-B): 15/88 (17.0 percent); -histona: 15/88 (17 percent); -PM / Scl: 13/88 (14.8 percent); -ADNsc: 11/88 (12.5 percent) and -ENAc individual: 8/88 (9.1 percent). The sensitivity of IFI-HEp-2 for antinuclear specificities was 0.83 (95 percent CI: 0.72-0.93). No history of rheumatic disease associated with ANA was read in (26/31) 83.9 percent patients with negative subserology. Conclusions: The majority of patients with discordant results between the first and second level of ANA were positive of less common antinuclear specificities, but of recognized diagnostic value(AU)
Subject(s)
Humans , Algorithms , Mass Screening , Antibodies, Antinuclear , Rheumatic Diseases/diagnosis , Prospective StudiesABSTRACT
Objective To establish mixed-sandwich ELISA detection system by screening aptam-ers of MPT64 antibodies with SELEX to detect clinical serum samples, and explore the potential laboratory diagnosis value of this method. Methods To detect the affinity of the final round ssDNA library to MPT64 antibodies inhibited by MPT64 antigen with the competitive ELISA method, optimize the mixed-sandwich ELISA detection method that was aptamer-serum-horseradish peroxidase labeled goat anti-human IgG anti-body detection system to detect 230 cases of clinical serum samples as well as the lowest concentration of MPT64 antibodies and the linear range. Results In competitive ELISA test results, the percentage of inhi-bition effect of MPT64 antigen to final round ssDNA library is from 0.25% to 80% when the MPT64 antigen concentration rised from 2 μg/ml to 256 μg/ml. The Optimized detection system of mixed-sandwich ELISA was constitute of the concentration of ssDNA coated with 0.1μg/hole, serum dilution of 1/200, horseradish peroxidase labeled goat anti-human IgG antibody concentration of 1/40 000. The lowest concentration of MPT64 antibody is 3 mg/L and the linear range is between 10 mg/L and 1000 mg/L. The serum samples of 100 cases of tuberculosis patients, 100 healthy individuals and 30 cases of non-tuberculesis were tested in this system and the test result was analyzed with Graphpad Prism, the difference of tuberculosis group and healthy group was statistically significant (P<0.001 ), the difference of TB group and non-TB control group was also statistically significant (P<0.001). The specificity and the sensitivity was 96.1% and 31.0% re-spectively. Conclusion The aptamer mixed-sandwich ELISA method will play an important role in the sero-logical diagnosis of tuberculosis.
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To obtain the aptamers with high affinity and specificity for cyclosporin A(CsA),a synthesized 78 nt single stranded DNA(ssDNA)random library containing 35 random sequences flanked by invariant primer was subjected to 1 1 rounds of selection against CsA by SELEX protocol.Magnetic beads were used for target immobilization and the biotin-streptavidin-horseradish peroxidase system was employed for determining the binding affinity between the aptamers and CsA. After ten rounds of selection and amplification, with an increasing affinity for each round,the selected aptamers were cloned,sequenced and analyzed for their primaryand secondary structures.The 19 aptamers were divided into five groups based on primary sequence homology.Hairpin loop is the main motif in the predicted secondary structure and is supposed to be the binding part of the aptamers to CsA.The CsA-specific aptamers will be useful for enzyme-linked assays or immunofluorescence asses of CsA.