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Aldo Roda

Publications and source records attributed to Aldo Roda.

39 records · Page 3Linked to original sources

Microtiter format for simultaneous multianalyte detection and development of a PCR-chemiluminescent enzyme immunoassay for typing human papillomavirus DNAs.

BACKGROUND: To allow multianalyte binding assays, we have developed a novel polystyrene microtiter plate containing 24 main wells, each divided into 7 subwells. We explored its clinical potential by developing a PCR-chemiluminescent immunoassay (PCR-CLEIA) for simultaneous detection and typing of seven high oncogenic risk human papillomavirus (HPV) DNAs in one well. METHODS: Seven different oligonucleotide probes, each specific for a high-risk HPV genotype, were separately immobilized in the subwells. Subsequently, a digoxigenin-labeled consensus PCR amplification product was added to the main well. The PCR product hybridized to the immobilized probe corresponding to its genotype and was subsequently detected by use of a peroxidase-labeled anti-digoxigenin antibody and chemiluminescence imaging with an ultrasensitive charge-coupled device camera. Results obtained for 50 cytologic samples were compared with those obtained with a conventional colorimetric PCR-ELISA. RESULTS: The method was specific and allowed detection of 50 genome copies of HPV 16, 18, 33, and 58, and 100 genome copies of HPV 31, 35, and 45. Intra- and interassay CVs for the method were 5.6% and 7.9%, respectively. All results obtained for clinical samples were confirmed by the conventional PCR-ELISA. CONCLUSIONS: PCR-CLEIA allows rapid, single-tube simultaneous detection and typing of seven high-risk HPV DNAs with small reagent volumes. The principle appears applicable to the development of other single-tube panels of tests.

DNA, Viral↗

Hollow-fiber flow field-flow fractionation: a gentle separation method for mass spectrometry of native proteins.

Low-impact ionization sources like electrospray ionization (ESI) and matrix-assisted, laser desorption/ionization (MALDI) equipped with time-of-flight (TOF) mass analyzers provide intact protein analysis over a very wide molar mass range. ESI/TOFMS provides also indications on the higher-order structure of intact proteins and non-covalent protein complexes. However, direct analysis of intact proteins mixtures in real samples shows limited success, mainly because spectra become very complex to interpret. This is also due to sample contaminants, and to the mechanism of competitive ionization in ESI or MALDI. Rapid and efficient sample clean-up and separation methods can significantly enhance the power of TOFMS for intact protein analysis. However, if protein native conditions want to be maintained, the methods should affect neither the three-dimensional structure nor the non-covalent chemistry of the proteins. Reversed-phase (RP) HPLC, size-exclusion chromatography (SEC), and capillary zone electrophoresis (CZE) are on-line or off-line coupled to ESI/TOFMS or MALDI/TOFMS. In fact, these separation methods often show limitations when applied to the analysis of native proteins. Organic modifiers and saline buffers are required in the case of RP HPLC or CZE. They can induce protein degradation or affect ionization when MS is performed after separation. High voltages used in CZE can contribute to alter proteins from their native form. In the case of high molar mass proteins, SEC is scarcely selective, and barely able to detect protein aggregates. Sample entanglement/adsorption on the stationary phase can also occur.

Chromatography, Gel↗

A rapid and sensitive 384-well microtitre format chemiluminescent enzyme immunoassay for 19-nortestosterone.

We developed a competitive chemiluminescent (CL) enzyme immunoassay for rapid, sensitive analysis of 19-nortestosterone (19-NT) in bovine urine. Anti-19-NT polyclonal antibodies were raised in rabbits using a 19-NT-hemisuccinate derivative conjugated with ovalbumin; the derivative was also conjugated with horseradish peroxidase (HRP) as a label. Antibodies were immobilized on 384-well black polystyrene microtitre plates and HRP-labelled 19-NT activity was measured using an efficient chemiluminescent substrate (SuperSignal ELISA Femto) after 3 min incubation. Emitted light was recorded using a conventional, photomultiplier-tube-based microtitre plate reader or a sensitive back-illuminated, cooled CCD camera. The developed method fulfils all the requirements of precision (intra- and inter-assay CV < 10%) and accuracy (mean recovery 94-112%), with a detection limit of 0.03 ppb (1.1 x 10(-9) mol/L) in a urine matrix. Chemiluminescence enhances detectability of the HRP-labelled tracer (thus lowering the limit of detection with respect to colorimetry) and reduces analysis time. The 384-well microtitre plate cuts the sample/reagent volume (20 microL), a five-fold reduction with respect to the conventional 96-well microtitre plate. The developed method is suitable for high-throughput screening of 19-NT in urine samples, with reduced costs as compared with conventional colorimetric enzyme immunoassays.

Anabolic Agents↗