RESUMO
It presents a study approaching diagnostic technologies for global public health. It brings an overview of global health issues, diagnostic tools used in developed-world centralized labs, potential benefits of microfluidic diagnostic systems. Document in PDF format, required Acrobat Reader.
Assuntos
Técnicas de PesquisaRESUMO
The developing world does not have access to many of the best medical diagnostic technologies; they were designed for air-conditioned laboratories, refrigerated storage of chemicals, a constant supply of calibrators and reagents, stable electrical power, highly trained personnel and rapid transportation of samples. Microfluidic systems allow miniaturization and integration of complex functions, which could move sophisticated diagnostic tools out of the developed-world laboratory. These systems must be inexpensive, but also accurate, reliable, rugged and well suited to the medical and social contexts of the developing world.
Assuntos
Testes Diagnósticos de Rotina/métodos , Internacionalidade , Microfluídica/métodos , Saúde Pública/métodos , Países em Desenvolvimento/economia , Testes Diagnósticos de Rotina/economia , Testes Diagnósticos de Rotina/instrumentação , Humanos , Microfluídica/economia , Microfluídica/instrumentação , Saúde Pública/tendênciasRESUMO
BACKGROUND: Retinol-binding protein (RBP) was chosen as a surrogate marker for retinol because of the close correspondence between retinol and RBP. OBJECTIVE: To meet the need for rapid, cost-effective determination of vitamin A status in populations, a quantitative enzyme immunoassay (EIA) for detection of RBP was developed. DESIGN: The resulting RBP EIA, a competitive assay, uses RBP adsorbed to microtest strip wells to compete with RBP in serum. The assay takes approximately 40 min. RESULTS: With a reference panel of sera, test accuracy was found to be within 4% of expected values through the calibrated range of 0.48-1.92 micro mol RBP/L (10-40 micro g RBP/mL). Intraassay and interassay variability averaged 6.7% and 8.9%, respectively. Specificity testing showed no interference from other serum proteins, prealbumin, rheumatoid factor, bilirubin, estrogen, or C-reactive protein. The RBP EIA provided linear results between 0.43 and 1.80 micro mol RBP/L (9 and 38 micro g RBP/mL). Preliminary laboratory evaluations indicated that the RBP EIA correlates well with radial immunodiffusion for RBP and with HPLC for retinol, the current reference standard. A field evaluation in a population at risk for vitamin A deficiency (VAD) resulted in close correlation between RBP EIA measures and retinol measures by HPLC (R(2) = 0.82). CONCLUSIONS: The RBP EIA is as reliable in estimating VAD as is HPLC retinol. After successful validations, the test should enable public health authorities to rapidly monitor VAD and track vitamin A status in populations.
Assuntos
Técnicas Imunoenzimáticas/métodos , Proteínas de Ligação ao Retinol/metabolismo , Vitamina A/sangue , Adulto , Criança , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Fitas Reagentes , Reprodutibilidade dos TestesRESUMO
Haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmitted disease that increases the rate of transmission of human immunodeficiency virus. Chancroid ulcerations are difficult to distinguish from those produced by syphilis and herpes. Diagnosis based solely on clinical grounds is inaccurate, and culture is insensitive. Highly sensitive PCR has largely superseded culture as the preferred method of laboratory diagnosis; however, neither culture nor PCR is feasible where chancroid is endemic. We developed a rapid (15-min) diagnostic test based on monoclonal antibodies (MAbs) to the hemoglobin receptor of H. ducreyi, HgbA. This outer membrane protein is conserved in all strains of H. ducreyi tested and is required for the establishment of experimental human infection. MAbs to HgbA were generated and tested for cross-reactivity against a panel of geographically diverse strains. Three MAbs were found to be unique and noncompetitive and bound to all strains of H. ducreyi tested. Using an immunochromatography format, we evaluated the sensitivity and specificity of the test using geographically diverse strains of H. ducreyi, other Haemophilus strains, and other bacteria known to superinfect genital ulcers. All H. ducreyi strains were positive, and all other bacteria were negative, resulting in a specificity of 100%. The minimum number of CFU of H. ducreyi detected was 2 x 10(6) CFU, and the minimum amount of purified HgbA protein detected was 8.5 ng. Although this level of sensitivity may not be sufficient to detect H. ducreyi in all clinical specimens, further work to increase the sensitivity could potentially make this a valuable bedside tool in areas where chancroid is endemic.
Assuntos
Antígenos de Bactérias/análise , Proteínas da Membrana Bacteriana Externa/análise , Proteínas de Bactérias , Proteínas de Transporte/análise , Haemophilus ducreyi/isolamento & purificação , Testes Imunológicos/métodos , Anticorpos Monoclonais , Antígenos de Bactérias/imunologia , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/imunologia , Proteínas de Transporte/genética , Proteínas de Transporte/imunologia , Cancroide/microbiologia , Ensaio de Imunoadsorção Enzimática/métodos , Haemophilus ducreyi/química , Haemophilus ducreyi/genética , Haemophilus ducreyi/imunologia , Humanos , Imunoquímica , Reação em Cadeia da Polimerase/métodosRESUMO
We evaluated a prototype immunochromatographic strip (ICS) test for qualitative detection of Treponema pallidum antibodies in 353 sera from 157 patients. For sera from 43 syphilis patients, the ICSs were reactive, while for sera from 114 patients without syphilis, including 22 with biologically false-positive Rapid Plasma Reagin test results, the ICSs were nonreactive. The ICS test may expand the available options for serological testing for syphilis.
