A critical review of melatonin assays: Past and present.

There has been increased interest in the measurement of melatonin in plasma and saliva recently either as a marker of circadian phase or to understand the physiological role of melatonin. For both situations, there is a need for a specific assay for melatonin that is sensitive enough to detect low concentrations (<2 pg/mL). Since the mid-1970s, there have been many assays developed to measure melatonin in blood and saliva. Radioimmunoassays and ELISA have predominated because of their relative simplicity and high throughput. In this review, I show that the early radioimmunoassays while providing valuable information about nocturnal melatonin levels in humans, generally produced inaccurate basal (daytime) levels. Mass spectrometry assays, however, have provided us with the target values that immunoassays need to achieve, that is, daytime plasma melatonin levels <1 pg/mL. There are now many contemporary commercial assays available utilising both RIA and ELISA technologies, but not all achieve the standards set by the mass spectrometry assays. The performance of these assays is reviewed. I conclude with recommendations on issues researchers need to consider when conducting melatonin studies, including the importance of time of day of collection, validation of assays, the potential causes of poor assay specificity at low levels, the advantages/disadvantages of using saliva vs plasma and extraction assays vs direct assays, kit manufacturers responsibilities and the reporting requirements when publishing melatonin studies.

Innovative and New Approaches to Laboratory Diagnosis of Zika and Dengue: A Meeting Report.

Epidemics of dengue, Zika, and other arboviral diseases are increasing in frequency and severity. Current efforts to rapidly identify and manage these epidemics are limited by the short diagnostic window in acute infection, the extensive serologic cross-reactivity among flaviviruses, and the lack of point-of-care diagnostic tools to detect these viral species in primary care settings. The Partnership for Dengue Control organized a workshop to review the current landscape of Flavivirus diagnostic tools, identified current gaps, and developed strategies to accelerate the adoption of promising novel technologies into national programs. The rate-limiting step to bringing new diagnostic tools to the market is access to reference materials and well-characterized clinical samples to facilitate performance evaluation. We suggest the creation of an international laboratory-response consortium for flaviviruses with a decentralized biobank of well-characterized samples to facilitate assay validation. Access to proficiency panels are needed to ensure quality control, in additional to in-country capacity building.

European Union funded project on the development of a whole complement deficiency screening ELISA-A story of success and an exceptional manager: Mohamed R. Daha.

A whole complement ELISA-based assay kit, primarily designed to screen for deficiencies in components of the complement system was developed during a European Union grant involving more than a dozen European scientists and a small-medium enterprise company (Wieslab, which later merged into Eurodiagnostica). The consortium was led by Prof. Mohamed R. Daha who had already guided a preceding European grant which prepared the ground for this endeavor to create a novel and sophisticated complement measurement tool. The final result of the grant was a scientific publication (Seelen et al., 2005, J. Immunol. Methods 296, 187-198) and a commercially available complement deficiency screening kit, WIESLAB(®) Complement system Screen. Thereafter, the group decided to carry on with a grant, located at Innsbruck Medical University, and supported by royalties and unrestricted educational grants from Eurodiagnostica, Malmö, entitled "Search for Applications for WIESLAB(®) Complement system Screen (SAW)" with the aim to look for further applications of this assay. During the latter project the group organized several scientific meetings aimed at evaluating the use of the assay as well as developing further branches of its platform. A look back over almost two decades reveals a great story of excellent research which was also commercially successful, fulfilling the aims of European Union grants. It is also a story of ageless friendship, only possible due to the vision and guidance of an exceptional manager: Moh Daha.

A short history, principles, and types of ELISA, and our laboratory experience with peptide/protein analyses using ELISA.

Playing a critical role in the metabolic homeostasis of living systems, the circulating concentrations of peptides/proteins are influenced by a variety of patho-physiological events. These peptide/protein concentrations in biological fluids are measured using various methods, the most common of which is enzymatic immunoassay EIA/ELISA and which guide the clinicians in diagnosing and monitoring diseases that inflict biological systems. All the techniques where enzymes are employed to show antigen-antibody reactions are generally referred to as enzymatic immunoassay EIA/ELISA method. Since the basic principles of EIA and ELISA are the same. The main objective of this review is to present an overview of the historical journey that had led to the invention of EIA/ELISA, an indispensible method for medical and research laboratories, types of ELISA developed after its invention [direct (the first ELISA method invented), indirect, sandwich and competitive methods], problems encountered during peptide/protein analyses (pre-analytical, analytical and post-analytical), rules to be followed to prevent these problems, and our laboratory experience of more than 15 years.

Chapter 5. Potential contribution of sero-epidemiological analysis for monitoring malaria control and elimination: historical and current perspectives.

Anti-malarial antibody responses represent an individual's history of exposure to the disease and, as age sero-conversion rates, reflect cumulative malaria exposure in a population. As such these antibody responses are an alternate measure of malaria transmission intensity and have potential in evaluating changes in exposure. This approach was used in the 1970s to evaluate malaria control and eradication attempts in a variety of different ecological settings. These historical studies provided a wealth of information on how serological data might be used to interpret control measures. However they were limited by a lack of standardized antigens and reproducible high-throughput assays. Current techniques using recombinant antigens with a range of immunogenicities, high-throughput enzyme-linked immunosorbent assays (ELISA) and statistical analysis allow a more robust examination of how serological parameters can be used to evaluate factors affecting malaria transmission. Here we present a review of the historical data and use it to assess the serological contribution to monitoring malaria elimination.

A quarter of a century in anticardiolipin antibody testing and attempted standardization has led us to here, which is?

The anticardiolipin (aCL) test has been widely used by physicians since the mid-1980s for diagnosing patients with antiphospholipid syndrome (APS). Establishment of this diagnosis has enabled effective management of patients with recurrent thrombosis and recurrent pregnancy losses. The test was first established in 1983 as a radioimmunoassay and soon thereafter converted into an enzyme-linked immunosorbent assay (ELISA). The other test commonly used in the diagnosis of APS is the lupus anticoagulant (LA) test. The aCL ELISA is sensitive for the diagnosis of APS but lacks specificity. On the other hand, the LA assay, although more specific, is not as sensitive as the aCL ELISA. More specific tests are now available such as the anti-beta2 glycoprotein I (anti-beta2GPI) assay, the antiprothrombin assay, and other ELISAs that use negatively charged phospholipids instead of cardiolipin to coat the plates. In the past 25 years, there have been numerous efforts to standardize aCL, LA, and anti-beta2GPI tests but there are still reports of significant intra- and interlaboratory variation in results for all three assays. This article discusses in detail the clinical value of these tests, technical problems associated with their use, the current laboratory classification criteria for diagnosis of APS, and possible new and better assays that will be available in the near future for diagnosis of APS.

Enzyme immunoassay (EIA)/enzyme-linked immunosorbent assay (ELISA).

This brief note addresses the historical background of the invention of the enzyme immunoassay (EIA) and enzyme-linked immunosorbent assay (ELISA). These assays were developed independently and simultaneously by the research group of Peter Perlmann and Eva Engvall at Stockholm University in Sweden and by the research group of Anton Schuurs and Bauke van Weemen in The Netherlands. Today, fully automated instruments in medical laboratories around the world use the immunoassay principle with an enzyme as the reporter label for routine measurements of innumerable analytes in patient samples. The impact of EIA/ELISA is reflected in the overwhelmingly large number of times it has appeared as a keyword in the literature since the 1970s. Clinicians and their patients, medical laboratories, in vitro diagnostics manufacturers, and worldwide healthcare systems owe much to these four inventors.

Chemistry and biology of the ELISPOT assay.

Enzyme-linked immunospot, or ELISPOT, assay allows the detection of low frequencies of cells secreting various molecules. ELISPOT can be used in many areas of research and, because of its high sensitivity, has the potential to become a valuable diagnostic tool. Based on the same "sandwich" immunochemical principles as enzyme-linked immunosorbent assay, ELISPOT is easy to perform and quantify the results. At the same time ELISPOT remains a state-of-the-art technique that requires accuracy, thorough selection of antibodies and detection reagents, and an understanding of the principles of data analysis. This review covers various technical aspects of the ELISPOT assay, including immunochemical principles of the assay, selection of reagents and plates, and troubleshooting recommendations.

ELISPOT assay: a personal retrospective.

In 1983, papers describing the enzyme-linked immunospot (ELISPOT) technique were published by two groups, the first description from a team in Perth, Western Australia, and the second, soon thereafter, from a group in Gothenburg, Sweden. Described here is my recollection of the background and circumstances that lead to the assay's development within the Perth group. Included are the early studies in 1981 through early 1982 that were conducted to bring the assay to fruition both setbacks and solutions, and finally some generally unknown but amusing insights into the naming of the ELISPOT assay by the Gothenburg group.

Membranes and membrane plates used in ELISPOT.

Membrane-bottomed, 96-well plates constitute the format in which the overwhelming majority of enzyme-linked immunospot (ELISPOT) assays are performed. The membranes in these plates are made from either nitrocellulose or polyvinylidene fluoride. These membranes are well suited for ELISPOT because they have high antibody binding capacities and because their white color provides an excellent backdrop for ELISPOT enumeration. These two membranes and, ultimately, the 96-well plates used in ELISPOT assays were commercialized for filtration applications and later optimized for deoxyribonucleic acid hybridization and protein chemistry applications. In this chapter, an overview of the development and biotechnology applications of nitrocellulose and polyvinylidene fluoride membrane is provided and characteristics and attributes of each of the membranes that are relevant to ELISPOT are summarized.

Hugh Alistair Reid OBE MD: investigation and treatment of snake bite.

Alistair Reid was an outstanding clinician, epidemiologist and scientist. At the Penang General Hospital, Malaya, his careful observation of sea snake poisoning revealed that sea snake venoms were myotoxic in man leading to generalized rhabdomyolysis, and were not neurotoxic as observed in animals. In 1961, Reid founded and became the first Honorary Director of the Penang Institute of Snake and Venom Research. Effective treatment of sea snake poisoning required specific antivenom which was produced at the Commonwealth Serum Laboratories in Melbourne from Enhydrina schistosa venom supplied by the Institute. From the low frequency of envenoming following bites, Reid concluded that snakes on the defensive when biting man seldom injected much venom. He provided clinical guidelines to assess the degree of envenoming, and the correct dose of specific antivenom to be used in the treatment of snake bite in Malaya. Reid demonstrated that the non-clotting blood of patients bitten by the pit viper, Calloselasma rhodostoma [Ancistrodon rhodostoma] was due to venom-induced defibrination. From his clinical experience of these patients, Reid suggested that a defibrinating derivative of C. rhodostoma venom might have a useful role in the treatment of deep vein thrombosis. This led to Arvin (ancrod) being used clinically from 1968. After leaving Malaya in 1964, Alistair Reid joined the staff of the Liverpool School of Tropical Medicine, as Senior Lecturer. Enzyme-linked immunosorbent assay (ELISA) for detecting and quantifying snake venom and venom-antibody was developed at the Liverpool Venom Research Unit: this proved useful in the diagnosis of snake bite, in epidemiological studies of envenoming patterns, and in screening of antivenom potency. In 1977, Dr H. Alistair Reid became Head of the WHO Collaborative Centre for the Control of Antivenoms based at Liverpool.