Rapid enzyme-linked immunosorbent assay (ELISA) with a visual end-point for detecting quinine in urine, serum and dried blood spots

The Analyst ◽  
1987 ◽  
Vol 112 (10) ◽  
pp. 1437 ◽  
Author(s):  
Vibeke Rowell ◽  
Frederick John Rowell
2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Anders Persson ◽  
Charlotte Becker ◽  
Ida Hansson ◽  
Anita Nilsson ◽  
Carina Törn

To evaluate the performance of dried blood spots (DBSs) with subsequent analyses of glutamic acid decarboxylase (GADA) and islet antigen-2 (IA-2A) with the RSR-ELISAs, we selected 80 children newly diagnosed with type 1 diabetes and 120 healthy women. DBSs from patients and controls were used for RSR-ELISAs while patients samples were analysed also with in-house RIAs. The RSR-ELISA-GADA performed well with a specificity of 100%, albeit sensitivity (46%) was lower compared to in RIA (56%;P=.008). No prozone effect was observed after dilution of discrepant samples. RSR-ELISA-IA-2A achieved specificity of 69% and sensitivity was lower (59%) compared with RIA (66%;P<.001). Negative or low positive patients and control samples in the RSR-ELISA-IA-2A increased after dilution. Eluates from DBS can readily be used to analyse GADA with the RSR-ELISA, even if low levels of autoantibodies were not detected. Some factor could disturb RSR-ELISA-IA-2A analyses.


2019 ◽  
Author(s):  
Mark Andy Xatse ◽  
Jewelna Akorli ◽  
Irene Offei Owusu ◽  
Livingstone Gati ◽  
Michael David Wilson

AbstractDried filter blood spots have become a significant blood collection method for screening individuals for clinical purposes. When used for ELISAs, they are normally discarded after the blood has been eluted. However, they may still be useful for extraction of DNA for molecular-based assays. The aim of this work was to determine the integrity of DNA extracted from filter paper spots from which blood has initially been eluted for ELISA with sample dilution buffer (SDB) and phosphate buffered saline (PBS). DNA was extracted from the eluted filter spots, the eluate, and dried blood filter spots (controls) using spin column extraction. The quality and quantity of the extracted DNA was assessed and used for PCR to further evaluate their usefulness in molecular assays. Concentration of DNA obtained was dependent on the buffer used for processing the filter blood blots. Accounting for the DNA concentration obtained from dried blood spots, which were used as controls, DNA extracted from the already eluted blood spots were 32 times higher in PBS than SDB processed filter paper. The ratio was even higher for the eluates, which were 57 times higher in PBS than SDS eluates. SDB eluates had significantly higher average DNA concentration than their eluted filter paper, but their purity ratios were similar. 85% PCR success rate was achieved with the DNA samples. Useful DNA can be extracted from blood spots after it has been eluted with SDB. Although the DNA concentration and purity may be low, the DNA could be useful for rather simple PCR assays.Author SummaryCollection of blood onto filter paper has become an accepted method for screening individuals for clinical and public health purposes since the 1960s. This method of blood collection has become increasingly popular due to its ease and convenience in collection and transportation. The use of dried blood spots for clinical evaluations and research has become very significant. For research purposes, DBS when used for ELISAs are discarded after single use. DNA may however be extracted from the used filter blots and used for molecular assays. The concentration of DNA obtained may be low but simple assays like PCR could be done using the DNA extracted from the eluted filter spot.


1979 ◽  
Vol 9 (1) ◽  
pp. 38-48 ◽  
Author(s):  
G A Dasch ◽  
S Halle ◽  
A L Bourgeois

A microtiter enzyme-linked immunosorbent assay (ELISA) has been developed for the titration of antibodies against scrub typhus in human and animal sera. Scrub typhus rickettsiae were grown in monolayers of irradiated mouse LM3 cells and separated from host cell materials by differential centrifugation, filtration through a glass filter (AP-20, Millipore Corp.), and isopycnic banding in Renografin density gradients. The scrub typhus ELISA antigens were obtained from the purified viable rickettsiae by French pressure cell disruption and addition of 0.2% Formalin to the soluble extract. Antisera prepared in rabbits against the prototype Karp, the Kato, and the Gilliam strains of scrub typhus were used to standardize the ELISA and to compare its sensitivity and specificity to that of the indirect fluorescent antibody test (IFA). ELISA titers were measured as the greatest serum dilution showing an optical density 0.25 above controls or by the optical density achieved at a fixed serum dilution. The IFA and ELISA end point titers were quite similar, and all three measures of titer had comparable specificity for the strains of scrub typhus. No cross-reactions between the typhus and scrub typhus wera were observed by ELISA. Both the immunoglobulin M (IgM) and IgG antibody titers of 12 sequential sera from four patients with scrub typhus were obtained by IFA and ELISA. The IFA and ELISA end point titers for IgM and IgG had correlation coefficients of 0.91 and 0.97, respectively, whereas the ELISA optical density values at a serum dilution of 1:100 had slightly lower correlations with IFA titers (0.80 and 0.94). Early rising IgM titers followed by rising IgG titers were demonstrated by ELISA in three patients with primary scrub typhus infections, whereas the IgG response predominated in a patient with a reinfection. It is concluded that the ELISA for scrub typhus is a very satisfactory alternative to the IFA test.


1984 ◽  
Vol 47 (12) ◽  
pp. 964-967 ◽  
Author(s):  
TITAN S. L. FAN ◽  
GUANG S. ZHANG ◽  
F. S. CHU

An indirect enzyme-linked immunosorbent assay (ELISA) which can detect 0.2 to 1 ng of T-2 toxin per ml in urine, serum and milk was developed. T-2 hemisuccinate was conjugated to polylysine which was then coated to a microtiter plate and incubated with rabbit anti-T-2 antibody and sample extract. The amount of anti-T-2 antibody bound to the plate was then determined by reaction with goat anti-rabbit IgG-peroxidase complex and by subsequent reaction with the substrate. Samples spiked with T-2 toxin were subjected to a simple cleanup procedure by passing them through a reversed-phase Sep-Pak catridge (C18). The recoveries of tritiated T-2 toxin added to the urine, serum and milk samples were between 71 to 90% after the cleanup step. In the ELISA, significant interference was observed when more than 5 μl of sample, without cleanup treatment, were used in each analysis. After cleanup, extracts equivalent to 50 μl of serum, urine or milk per well did not significantly interfere with the assay. The recoveries of T-2 toxin added to serum (1 to 10 ng/ml), urine (0.2 to 10 ng/ml) and milk (0.2 to 10 ng/ml) after cleanup treatment as determined by the indirect ELISA were found to be 51 to 82%, 73 to 82% and 80 to 83%, respectively.


Author(s):  
Sam L. Nsobya ◽  
Paul C. Hewett ◽  
Sam Kalibala ◽  
Barbara S. Mensch

This study evaluated the performance of the Kalon Biological HSV2 IgG enzyme-linked immunosorbent assay (Kalon Biological Ltd, Surrey, United Kingdom) on dried blood spots (DBS) of various dilutions compared with plasma from young women aged 18–24 years in Uganda. We estimated the sensitivity and specificity of three DBS dilutions using plasma as the reference. All three evaluated DBS dilutions yielded low sensitivities and specificities, with DBS 1:2 yielding the highest concurrence. Other herpes simplex virus type 2 assays should be examined with regard to their utility for testing DBS.


The Analyst ◽  
1987 ◽  
Vol 112 (5) ◽  
pp. 687 ◽  
Author(s):  
David Laurie ◽  
Andrew J. Manson ◽  
Andrew Mounsey ◽  
Frederick J. Rowell ◽  
John Seviour

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