Recordando nuestra historia: hace 60 años se descubrió el radioinmunoanálisis / Remembering our history: 60 years ago radioimmunoanalysis was discovered

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How technical progress reshaped behavioral neuroendocrinology during the last 50 years and some methodological remarks.

The first issue of Hormones and Behavior was published 50 years ago in 1969, a time when most of the techniques we currently use in Behavioral Endocrinology were not available. Researchers have during the last 5 decades developed techniques that allow measuring hormones in small volumes of biological samples, identify the sites where steroids act in the brain to activate sexual behavior, characterize and quantify gene expression correlated with behavior expression, modify this expression in a specific manner, and manipulate the activity of selected neuronal populations by chemogenetic and optogenetic techniques. This technical progress has considerably transformed the field and has been very beneficial for our understanding of the endocrine controls of behavior in general, but it did also come with some caveats. The facilitation of scientific investigations came with some relaxation of methodological exigency. Some critical controls are no longer performed on a regular basis and complex techniques supplied as ready to use kits are implemented without precise knowledge of their limitations. We present here a selective review of the most important of these new techniques, their potential problems and how they changed our view of the hormonal control of behavior. Fortunately, the scientific endeavor is a self-correcting process. The problems have been identified and corrections have been proposed. The next decades will obviously be filled with exciting discoveries in behavioral neuroendocrinology.

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.

A short history of hormone measurement.

Huge changes have occurred in the measurement of hormones over the last 50 years or so. Methods have become simplified, sensitivity has increased manyfold, and automation has allowed the analysis of large number of specimens in a single day. The most significant steps in the history of hormone measurement were the development of radioimmunoassay and later the production of monoclonal antibodies. There has also been increased commercialization, the technique has been applied to an ever-increasing range of substances, and radioactive measurement has been replaced with colorimetric, fluorescent, and chemiluminescent end-points. However, all these changes have not been without their problems. Collaboration between laboratories has seen standardization of reagents and methods, the development of reference methods, and the setting up of external quality assurance schemes. All these have led to improved sensitivity, precision, and reliability. More recently tandem mass spectrometry has brought further improvements in the measurement of certain hormones. Although many hormones are now measured by automated systems there is still a place for manual assays whether developed in-house or by using a commercial kit.

[Development of radioimmunoassay and its consequences in the medical research. A tribute to Rosalyn Yallow]. / El radioinmunoensayo y su impacto en la investigación. Tributo a Rosalyn Yallow.

Rosalyn Yalow lived all her life in the Bronx, New York, where she was born, educated, worked and met Solomon Berson, her scientific partner for a long time. Despite being a top student at Hunter College she was unable to be admitted to any graduate program in physics, mainly because she was Jewish and female. Later she joined the Veterans Administration Hospital in New York where she established the radioisotope laboratory. There she met Solomon Berson and formed the extraordinary scientific partnership and started publishing studies of radioactivity. Yalow received the Nobel Prize in Medicine and Phisiology or Medicine in 1977 and died on May 30, 2011.

Early milestones in glucagon research.

As an introduction to the Symposium, we have reviewed the early steps in glucagon research from its discovery in 1923 to the establishment of the basics of the physiology and pathophysiology of the hormone after the description of a sensitive and specific radioimmunoassay by Unger and his co-workers in 1959.

An overview of various labeled assays used in medical laboratory diagnosis. Immune and non-immune assays.

In this review, some light is thrown on various labeled immunoassays that depend on antigen-antibody (Ag-Ab) reactions, including immunofluorescence, radioimmunoassay, and enzyme immunoassay (EIA or ELISA). Their definitions, principles, and applications are described, then they are discussed chronologically to show their stepwise development that led finally to full automation. Enzyme labeled immunoblot assays (Western blot, blot spot, and recombinant immunoblot assay), and luminescence (bioluminescence and chemiluminescence) are also discussed chronologically. Labeled assays, that do not involve Ag-Ab reaction but rather, utilizing biotin-streptavidin (BS) interaction and probe-target DNA interaction, are described, together with their applications for DNA/RNA detection and genotyping. Finally, included in the discussion were some luminescent labeled techniques that utilize the immune Ag-Ab reaction together with non-immune BS reaction, such as the luminescent oxygen channeling immunoassay, and its commercialized AlphaLISA, both eliminate the washing steps without sacrificing high sensitivity, or wide dynamic range.

The insulin immunoassay after 50 years: a reassessment.

In 1960 Berson and Yalow published a method for the radioimmunoassay (RIA) of plasma insulin based on the concept that the extent to which unlabeled insulin displaces labeled insulin from anti-insulin antibody is proportional to the concentration of unlabeled insulin. The RIA for insulin has greatly increased knowledge of the physiology of glucose homeostasis and of the diverse causes of diabetes mellitus. Beyond this, the insight on which the RIA-or, more broadly, the competitive protein-binding assay-is based has provided the means to measure nanomolar or picomolar concentrations of a vast array of compounds in plasma and tissues. Directly or indirectly, the RIA has profoundly affected every branch of medicine. This essay reviews the ideas that were current in the medical research community when Berson and Yalow began their work and the observations and reasoning process that led them to their seminal discovery.