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.

Clinical applications of LC-MS sex steroid assays: evolution of methodologies in the 21st century

PURPOSE OF REVIEW

The purpose of this review is to summarize why and how liquid chromatography tandem mass spectrometry (LC-MS/MS) is increasingly replacing other methodologies for the measurement of sex steroids.

RECENT FINDINGS

Measurement of sex steroids, particularly testosterone and estradiol, is important for diagnosis or management of a host of conditions (e.g. disorders of puberty, hypogonadism, polycystic ovary syndrome, amenorrhea, and tumors of ovary, testes, breast and prostate). Historically, metabolites of testosterone and estradiol were measured as ketosteroids in urine using colorimetric assays that lacked sensitivity and specificity due to endogenous and exogenous interferences. Extracted competitive manual radio-immunoassays provided improved, but still imperfect, specificity, and offered increased sensitivity. As testing demand increased, they were displaced by automated immunoassays. These offered better throughput and precision, but suffered worse specificity problems. Moreover, agreement between different immunoassays has often been poor and they are all compromised by a limited dynamic measurement range. To overcome these problems, LC-MS/MS methods have been developed and validated for quantitation of sex steroids. These methods reduce interferences, provide better specificity, improve dynamic range, and reduce between-method bias.

SUMMARY

Endocrine Society and Urology Society guidelines have highlighted the limitations of the immunoassays for sex steroids and have provided convincing evidence that mass spectrometric methods are preferable for measurement of sex steroid hormones. In this review, we describe LC-MS/MS methods for measurement of testosterone and estradiol.

Modern laboratory evaluation of peptide and amines: a continuing role for radioimmunoassay?

Modern medicine, and specifically clinical diagnosis, relies, among other diagnostic procedures, on the measurements of the biogenic analytes for elucidation and correlation of specific neuroendocrine markers. Tremendous advances have been made in imaging and radioactive uptake procedures to elucidate tumor presence and characterization. However, such advances only partially provide the fundamental degree of tumor activity and clinical confirmational validity. The author points out in some detail the problems that may arise when the methodological differences presented by each investigational study and investigators are not standardized. This variation causes a concern with the specific objectives of the investigator and the specific aims of the research project at hand, and ultimately for the validity of the published results.

Evaluation of the immunotech cyclosporine direct radioimmunoassay for the determination of whole-blood cyclosporine in renal transplant patients

Therapeutic drug monitoring (TDM) of cyclosporine (CsA) has been an accepted as an essential tool in the management of solid organ transplant recipients. The authors evaluated a new CsA method, Immunotech cyclosporine direct radioimmunoassay (Beckman Coulter, Prague, Czech Republic), for the measurement of whole-blood CsA concentrations. The performance was compared with CEDIA Plus method as well as group mean data for HPLC and other immunoassays available from the International CsA Proficiency Testing Program (www.bioanalytics.co.uk). Regression analysis of patient samples gave a relationship of RIA = 1.0822 CEDIA(+) + 69.84 (r(2) = 0.933). External CsA-spiked proficiency-testing (PT) samples gave a regression equation of RIA = 0.9672 CEDIA(+) + 4.99 (r(2) = 0.996). The correlation with the CEDIA Plus method using patient specimens (hence, including CsA metabolites) suggested that the test RIA method possibly had slightly inferior specificity for parent CsA. The results suggest that the Immunotech cyclosporine direct RIA kit is suitable for the measurement of whole-blood CsA concentrations and maintained clinically acceptable analytic precision and accuracy, displaying CVs of less than 15% and biases of less than 10%. The PT program CsA-metabolite-free samples showed that calibration between methods was comparable with the possible exception of mFPIA/TDx.

[The progress and methodologic problems of in vitro radioassay]

The history of development of in vitro radioassays is reviewed. The basic principles and clinical uses of saturation analysis, competitive radioassay and immunoradiometric assay are described. The more rapid, sensitive, specific and accurate assays are required at all times. However, it is well known that autoantibodies or heterophilic antibodies in serum interfere with radioassay and cause false results. Here I present the technical problems of the assay in the presence of such interfering substances which need to be resolved and also discussed the discrepancy between bioactivity and immunoreactivity in the assay.

New perspectives in radioimmunoassay

In addition to providing the basis of 'ultrasensitive' immunoassays, nonisotopic labels permit development of 'user friendly' methodologies, including simple devices designed for extralaboratory use and intended to provide yes/no answers to basic diagnostic questions, for example, the presence of an infectious disease, the commencement of pregnancy etc. Immunosensors are also intended to fulfil these objectives (albeit yielding quantitative information), but despite much research the prospect of adequately sensitive instruments of this type remains remote. Finally, nonisotopic labels enable the development of a new generation of miniaturized multianalyte assays permitting in principle the determination of entire analyte menus in small samples of body fluids. Such technologies will resemble those employed in compact disk recorders and other data-storage devices, differing only in that light emitted from discrete zones on a solid surface is fluorescent (or possibly chemiluminescent) rather than reflected, and yields chemical rather than physical information. The emergence of such technologies, will, inter alia, facilitate the screening of entire populations for infectious disease, endocrine dysfunctions, genetic abnormalities etc. using, for example, finger-tip blood samples, throat and endocervical swabs, and hopefully will contribute to the large-scale diagnosis and ultimate reduction of disease.

Radioimmunoassay: an overview

The historical development, principle and theory of the radioimmunological test are described, together with the necessary test components, separation techniques and experimental procedure. The emphasis on different areas of diagnosis that rely on radioimmunoassay is compared for two institutions. Methods for the determination and presentation of reliability criteria are described, and the current status of quality control of radioimmunological methods is discussed. Three high grade mechanized systems and five fully mechanized or automated systems for radioimmunological assays are presented. Future trends in the development of radioimmunoassay can be predicted with the aid of general growth criteria.