SDS-PAGE of recombinant and endogenous erythropoietins: benefits and limitations of the method for application in doping control

Introduction of a PEGylated EPO conjugate as internal standard for EPO analysis in doping controls

Immunopurification of doping control samples is a mandatory necessity in erythropoietin (EPO) analysis during a confirmation procedure; moreover, it has become common practice to also immunopurify samples for the initial testing procedure. Typically used materials (e.g., Stemcell purification plate and MAIIA purification kit) rely on anti-EPO antibodies for purification. Also, the detection of EPO after electrophoretic separation and western blotting is based on a monoclonal anti-EPO antibody, clone AE7A5, directed against a 26 amino acid sequence of the N-terminal region of human EPO. While the electrophoretic separation and blot transfer efficiency can be monitored with reference standards and quality control samples, it is presently not possible to monitor the functionality of the entire sample preparation procedure. The reliance on antibodies for both purification and detection has complicated the implementation of an internal standard (ISTD). In this study, customized EPO-polyethylene glycol (PEG) conjugates were synthesized as potential ISTDs and assessed as to their compatibility with existing sample preparation procedures for urine and blood sample analysis using the most common immunopurification techniques. Moreover, probing for the impact of the ISTD on sodium N-lauroylsarcosinate ("sarcosyl") polyacrylamide gel electrophoresis (SAR-PAGE)-based EPO analysis concerning potential interference with target analytes was conducted. The presented data demonstrate that a 12-kDa PEG residue attached to human EPO represents a particularly useful construct to serve as ISTD for erythropoietin-receptor agonist (ERA) analysis. The conjugate is applicable to both urine and blood testing using the commonly employed purification techniques, supporting and improving result interpretations especially concerning specimens where the natural abundance of human EPO is low.

Assessing EPO stability in urine and comparing recombinant EPO detectability in matched urine, venous serum, and capillary serum following a controlled epoetin alfa administration

The instability of erythropoietin receptor agonists (ERAs, i.e., EPO) in urine presents a challenge to their detectability in doping control samples; however, this issue is not often seen in blood (serum) samples. With the anti-doping field beginning to transition into alternative blood collection technologies, it is important to understand recombinant EPO (rEPO) detectability in serum samples collected from one such capillary collection device, the Tasso+ SST. Twelve individuals were administered a single, 40 IU/kg dose of rEPO (epoetin alfa, EPOGEN®). Following administration, matched urine, venous serum, and capillary serum samples were concurrently collected. Urine aliquots were subject to various storage times and temperatures mimicking shipping conditions of doping control urine samples to assess EPO stability, while other urine aliquots, venous serum, and capillary serum aliquots were frozen until analysis to understand rEPO detectability across all three matrices. EPO and rEPO instability was identified in urine collected from 8 of 12 participants, especially in aliquots stored at room temperature and 37°C. In some of these unstable samples, rEPO was still detectable, while in others, no recombinant nor endogenous EPO was detectable and would have resulted in negative sample reports. Analyzing the concurrently collected urine, venous, and capillary serum samples, rEPO detectability was identical across the three matrices. In most cases, rEPO was detectable for at least 168 h post-administration. Noting greater stability in blood compared with urine, it is recommended that anti-doping authorities utilize this novel capillary serum collection technology to improve overall ERA detectability in doping control samples.

Indirect biomarkers of blood doping: A systematic review

The detection of blood doping represents a current major issue in sports and an ongoing challenge for antidoping research. Initially focusing on direct detection methods to identify a banned substance or its metabolites, the antidoping effort has been progressively complemented by indirect approaches. The longitudinal and individual monitoring of specific biomarkers aims to identify nonphysiological variations that may be related to doping practices. From this perspective, the identification of markers sensitive to erythropoiesis alteration is key in the screening of blood doping. The current Athlete Biological Passport implemented since 2009 is composed of 14 variables (including two primary markers, i.e., hemoglobin concentration and OFF score) for the hematological module to be used for indirect detection of blood doping. Nevertheless, research has continually proposed and investigated new markers sensitive to an alteration of the erythropoietic cascade and specific to blood doping. If multiple early markers have been identified (at the transcriptomic level) or developed directly in a diagnostics' kit (at a proteomic level), other target variables at the end of the erythropoietic process (linked with the red blood cell functions) may strengthen the hematological module in the future. Therefore, this review aims to provide a global systematic overview of the biomarkers considered to date in the indirect investigation of blood doping.

Achieving routine application of dried blood spots for erythropoietin receptor agonist analysis in doping control: low-volume single-spot detection at minimum required performance level

Background: Erythropoietin receptor agonists (ERAs) are substances prohibited in sports and currently monitored in urine and blood. There is a great interest in new matrices like dried blood spots (DBSs). Method: A direct method for the detection of ERAs in DBSs using one single spot of 25 μl has been optimized and validated. Results: Limits of detection close or equal to those required by the World Anti-Doping Agency for serum/plasma samples were achieved, using a volume 20-times lower. All analytes were stable for at least 90 days at room temperature. Conclusion: Method performance was comparable to the requirements established for blood samples and, thus, monitoring of ERAs is reliable in DBSs in the context of doping control.

Doping and sports endocrinology: growth hormone, IGF-1, insulin, and erythropoietin

Among the substances prohibited by the World Anti-Doping Agency, "peptide hormones, growth factors, related substances, and mimetics" are classified as prohibited both in- and out-of-competition in section S2. This work reviews growth hormone and its releasing peptides, insulin-like growth factor 1 as the main growth factor, insulin, and erythropoietin and other agents that affect erythropoiesis. This review analyzes the prevalence of use among professional athletes and gym clients, the forms of use, dosing, ergogenic effects and effects on physical performance, as well as side effects and anti-doping detection methods.

Data from a microdosed recombinant human erythropoietin administration study applying the new biotinylated clone AE7A5 antibody and a further optimized sarcosyl polyacrylamide gel electrophoresis protocol

Erythropoietin (EPO) is a hormone, which stimulates the production of red blood cells. Due to its performance-enhancing effect, it is prohibited by the World Anti-Doping Agency (WADA). In order to reduce the detection window of EPO doping, athletes have been applying low doses of recombinant EPO (e.g., <10 IU/kg body weight, daily or every second day) instead of larger doses twice or more per week (e.g., 30 IU/kg). Microdoses of Retacrit (epoetin zeta), an EPO biosimilar, were administered intravenously and subcutaneously to human males and females. Urine and serum samples were collected and analysed applying the new biotinylated clone AE7A5 EPO antibody and a further optimized sarcosyl polyacrylamide gel electrophoresis (SAR-PAGE) protocol. With the improved protocol, microdosed Retacrit (7.5 IU/kg body weight [BW]) was detectable for at least 52 h after intravenous administration. Detection windows were approximately the same for serum and urine and doubled after subcutaneous administration (~104 h). Previous studies applying different electrophoretic techniques and the not further optimized SAR-PAGE protocol revealed considerably shorter detection windows for recombinant human erythropoietin (rhEPO) microdoses. Because the new biotinylated antibody performed significantly more sensitive than the nonbiotinylated version, the new protocol will improve the sensitivity and hence detectability of recombinant EPO in doping control.

Safety and Efficacy of Combined Intramuscular/Intranasal RAZI-COV PARS Vaccine Candidate Against SARS-CoV-2: A Preclinical Study in Several Animal Models

Several vaccine candidates for COVID-19 have been developed, and few vaccines received emergency approval with an acceptable level of efficacy and safety. We herein report the development of the first recombinant protein-based vaccine in Iran based on the recombinant SARS-CoV-2 spike protein in its monomeric (encompassing amino acid 1-674 for S1 and 685-1211 for S2 subunits) and trimer form (S-Trimer) formulated in the oil-in-water adjuvant system RAS-01 (Razi Adjuvant System-01). The safety and immunity of the candidate vaccine, referred to as RAZI-COV PARS, were evaluated in Syrian hamster, BALB/c mice, Pirbright guinea pig, and New Zeeland white (NZW) rabbit. All vaccinated animals received two intramuscular (IM) and one intranasal (IN) candidate vaccine at 3-week intervals (days 0, 21, and 51). The challenge study was performed intranasally with 5×106 pfu of SARS-CoV-2 35 days post-vaccination. None of the vaccinated mice, hamsters, guinea pigs, or rabbits showed any changes in general clinical observations; body weight and food intake, clinical indicators, hematology examination, blood chemistry, and pathological examination of vital organs. Safety of vaccine after the administration of single and repeated dose was also established. Three different doses of candidate vaccine stimulated remarkable titers of neutralizing antibodies, S1, Receptor-Binding Domain (RBD), and N-terminal domain (NTD) specific IgG antibodies as well as IgA antibodies compared to placebo and control groups (P<0.01). Middle and high doses of RAZI-COV PARS vaccine significantly induced a robust and quick immune response from the third-week post-immunization. Histopathological studies on vaccinated hamsters showed that the challenge with SARS-CoV-2 did not induce any modifications in the lungs. The protection of the hamster was documented by the absence of lung pathology, the decreased virus load in the lung, rapid clearance of the virus from the lung, and strong humoral and cellular immune response. These findings confirm the immunogenicity and efficacy of the RAZI-COV PARS vaccine. Of the three tested vaccine regimens, the middle dose of the vaccine showed the best protective immune parameters. This vaccine with heterologous prime-boost vaccination method can be a good candidate to control the viral infection and its spread by stimulating central and mucosal immunity.

Proteoforms and their expanding role in laboratory medicine

The term “proteoforms” describes the range of different structures of a protein product of a single gene, including variations in amino acid sequence and post-translational modifications. This diversity in protein structure contributes to the biological complexity observed in living organisms. As the concentration of a particular proteoform may increase or decrease in abnormal physiological states, proteoforms have long been used in medicine as biomarkers of health and disease. Notably, the analytical approaches used to analyze proteoforms have evolved considerably over the years. While ligand binding methods continue to play a large role in proteoform measurement in the clinical laboratory, unanticipated or unknown post-translational modifications and sequence variants can upend even extensively tested and vetted assays that have successfully made it through the medical regulatory process. As an alternate approach, mass spectrometry—with its high molecular selectivity—has become an essential tool in detection, characterization, and quantification of proteoforms in biological fluids and tissues. This review explores the analytical techniques used for proteoform detection and quantification, with an emphasis on mass spectrometry and its various applications in clinical research and patient care including, revealing new biomarker targets, helping improve the design of contemporary ligand binding in vitro diagnostics, and as mass spectrometric laboratory developed tests used in routine patient care.

An optimized SDS-PAGE protocol with a new blotting system for the initial testing procedure of ESAs in doping control

Recombinant erythropoietins (rEPOs) are still among the substances endurance athletes use for doping. Detection methods are based on an electrophoretic separation of the proteins followed by a western blot and immunodetection with specific anti-EPO antibodies. In addition to IEF-PAGE, the SDS-PAGE method has been used to differentiate endogenous EPO from rEPOs by their molecular weight (MW). However, to adapt to new generations of rEPOs exhibiting higher MW, which were not well detected after SDS-PAGE, sodium lauroyl sarcosinate (SAR) is now used instead of sodium dodecyl sulfate (SDS) for the initial EPO testing procedure on doping control samples. The SAR-PAGE method is nevertheless expensive as it requires frequent buffer preparations using highly purified sarkosyl powder. In addition, this reagent needs to be handled with care due to acute toxicity by inhalation. The aim of this work was to improve the SDS-PAGE method by increasing its sensitivity and transfer of high-MW rEPOs. First, using a biotinylated primary anti-EPO antibody and avoiding the use of a secondary antibody increased the general sensitivity of both SDS-PAGE and SAR-PAGE to all rEPOs about four-fold. Then, by changing the buffer system during the protein transfer, with a CAPS buffer and a discontinuous buffer transfer system, high-MW rEPOs, EPO-Fc and CERA were transferred with higher efficiency and detected with high sensitivity. This optimized SDS-PAGE protocol could be adopted by anti-doping laboratories as an alternative to SAR-PAGE.

Horseradish-peroxidase-conjugated anti-erythropoietin antibodies for direct recombinant human erythropoietin detection: Proof of concept

Antidoping testing for recombinant human erythropoietin (EPO) is routinely performed by gel electrophoresis followed by western blot analysis with primary and secondary antibodies. The two antibody steps add more than 24 h to the testing time of a purified sample. The aim of this study was to test the concept of using directly horseradish-peroxidase (HRP)-conjugated anti-EPO primary antibody, without the need for a secondary antibody, to reduce the analysis time and eliminate non-specific cross-reactivity with secondary antibodies. An in-house, periodate coupling (R&D systems, clone AE7A5) and three commercially available anti-human EPO-HRP conjugates from Genetex, Novus Biologicals and Santa Cruz were evaluated for specificity and sensitivity, using recombinant human EPO standards, negative human urine samples and urine samples from an EPO excretion study. The in-house anti-EPO-HRP conjugate was performed as well as the current two-step application of unconjugated primary and secondary antibodies used in routine analysis, with comparable specificity and sensitivity. The analysis time was markedly reduced for purified samples from 25 h with the routine method down to 7 h with the in-house HRP conjugate. Of the three commercially available conjugates tested, only the Santa Cruz anti-EPO-HRP conjugate showed comparable specificity but had lower sensitivity to both the in-house and the antibody combination currently applied routinely. The other two commercially available conjugates (Genetex and Novus Biologicals) did not show any visible bands with the EPO standards. The results clearly demonstrate the potential utility of a directly HRP-conjugated anti-EPO antibody to reduce analysis time for EPO in doping control.

Improved detection methods significantly increase the detection window for EPO microdoses

To reproduce a potential doping scenario, a 2 week administration of recombinant erythropoietin (rEPO) microdoses alone or in combination with growth hormone (GH) microdoses (three times a week) was performed on healthy and athletic male subjects. The aim of this study was to evaluate the identification capability of rEPO in samples obtained during and post treatment. Detection was tested in urine and blood using the antidoping techniques for rEPO detection (iso-electric focusing (IEF)-, sodium-dodecyl-sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and for some urine samples the sarcosyl (SAR)-PAGE method) with some improvements: for blood samples, instead of a simple concentration step, immuno-extraction of EPO was performed for all urines to limit protein contamination that can affect migration. In addition, elution buffer modifications also improved the quality of migration. The use of a recently validated biotinylated anti-EPO antibody simplified the protocols, allowing a single transfer step instead of a double-blot even by IEF with a lowered background. The criteria for suspicious blood and urine samples by IEF were also re-evaluated. While endogenous EPO was not decreased over the course of the study, EPO microdoses were detectable in blood and urine between 24 h and 72 h after an administration. Detection in urine in combination with SDS-PAGE was the most sensitive combination for prolonged detection (100% identification after 48 h, 91% after 72 h), slightly better than IEF. Urine samples also tested by SAR-PAGE indicated a similar sensitivity of detection to SDS-PAGE. GH co-administration had no impact on rEPO elimination/detection.

Sensitivity and specificity of detection methods for erythropoietin doping in cyclists

Recombinant human erythropoietin (rHuEPO) is used as doping a substance. Anti‐doping efforts include urine and blood testing and monitoring the athlete biological passport (ABP). As data on the performance of these methods are incomplete, this study aimed to evaluate the performance of two common urine assays and the ABP. In a randomized, double‐blinded, placebo‐controlled trial, 48 trained cyclists received a mean dose of 6000 IU rHuEPO (epoetin β) or placebo by weekly injection for eight weeks. Seven timed urine and blood samples were collected per subject. Urine samples were analyzed by sarcosyl‐PAGE and isoelectric focusing methods in the accredited DoCoLab in Ghent. A selection of samples, including any with false presumptive findings, underwent a second sarcosyl‐PAGE confirmation analysis. Hematological parameters were used to construct a module similar to the ABP and analyzed by two evaluators from an Athlete Passport Management Unit. Sensitivity of the sarcosyl‐PAGE and isoelectric focusing assays for the detection of erythropoietin abuse were 63.8% and 58.6%, respectively, with a false presumptive finding rate of 4.3% and 6%. None of the false presumptive findings tested positive in the confirmation analysis. Sensitivity was highest between 2 and 6 days after dosing, and dropped rapidly outside this window. Sensitivity of the ABP was 91.3%. Specificity of the urine assays was high; however, the detection window of rHuEPO was narrow, leading to questionable sensitivity. The ABP, integrating longitudinal data, is more sensitive, but there are still subjects that evade detection. Combining these methods might improve performance, but will not resolve all observed shortcomings.

Transposon-modified antigen-specific T lymphocytes for sustained therapeutic protein delivery in vivo

A cell therapy platform permitting long-term delivery of peptide hormones in vivo would be a significant advance for patients with hormonal deficiencies. Here we report the utility of antigen-specific T lymphocytes as a regulatable peptide delivery platform for in vivo therapy. piggyBac transposon modification of murine cells with luciferase allows us to visualize T cells after adoptive transfer. Vaccination stimulates long-term T-cell engraftment, persistence, and transgene expression enabling detection of modified cells up to 300 days after adoptive transfer. We demonstrate adoptive transfer of antigen-specific T cells expressing erythropoietin (EPO) elevating the hematocrit in mice for more than 20 weeks. We extend our observations to human T cells demonstrating inducible EPO production from Epstein-Barr virus (EBV) antigen-specific T lymphocytes. Our results reveal antigen-specific T lymphocytes to be an effective delivery platform for therapeutic molecules such as EPO in vivo, with important implications for other diseases that require peptide therapy.

A validated, sensitive electrophoretic method for the detection of activin receptor type II-Fc fusion proteins in human blood

New therapeutic proteins that trap circulating members of the transforming growth factor (TGF) beta superfamily (activins and growth differentiation factors) show promising effects on erythropoiesis and muscular growth. They are dimeric recombinant fusion proteins composed of the extracellular domain of a human activin receptor (ActRIIA or IIB) linked to the Fc part of human IgG1. Sotatercept (ActRIIA-Fc) and Luspatercept (a modified ActRIIB-Fc) in particular are now in phase 2/3 of clinical trials against anemia and included in the prohibited list established by the World Anti-Doping Agency. To prevent a potential misuse by athletes in the near future, a robust and sensitive method of detection is needed. We validated an approach adapted from an electrophoretic method used for the detection of recombinant erythropoietins that allowed detection of various ActRIIA-Fc and ActRIIB-Fc proteins, including variants produced in different cell types, after a single immuno-extraction step. After separation by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), an initial testing procedure performed by single-blotting can indicate the presence of an ActRII-Fc (indifferently type IIA or IIB). A confirmation performed by double-blotting using different antibodies for detection allows a more precise identification of the type of ActRII-Fc (IIA, IIB). Starting from a few hundred microliters of serum or plasma, this method is specific, sensitive, and easy to perform. It could easily be adopted by anti-doping laboratories.

Utilizing ELISA-plate based immunopurification and liquid chromatography-tandem mass spectrometry for the urinary detection of short- and long acting human insulin analogues

The measurement of human insulin and its synthetic analogues in biological matrices has become increasingly important not only in clinical fields but also in doping control. The use of insulin and its analogues have been included in the list of prohibited substances published by the World Anti-Doping Agency (WADA). This study describes a qualitative method for detection of insulin analogues (lispro, aspart, glulisine, glargine, degludec, detemir) in human urine. The sample preparation consists of a preconcentration step using ultrafiltration followed by an immunoaffinity extraction with an antibody precoated ELISA plate. The obtained extracts are analyzed by conventional high-performance liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS). The limits of detection range between 10 pg/ml and 150 pg/ml. The applicability of the method was proven by the analysis of real urine samples obtained from diabetic patients treated with synthetic insulin analogues.

Evaluation of AMGEN clone 9G8A anti-Epo antibody for application in doping control

The two mouse monoclonal anti-erythropoietin (EPO) antibodies clone AE7A5 (generated by using a 26 amino acid N-terminal EPO-peptide) and 9G8A (developed by immunizing mice with full length human EPO) are both directed against linear epitopes at the N-terminus of EPO. While AE7A5 has been commercially available for many years, 9G8A was made for Amgen's internal research purposes. In the past, the commercial antibody was shown to cross-react with several proteins unrelated to EPO (e.g. E. coli thioredoxin reductase, zinc-α2-glycoprotein, S. cerevisiae enolase, human neuron-specific enolase, and human non-neuronal enolase). However, it displayed high sensitivity for detecting recombinant EPO (rEPO) misuse by athletes on Western blots. We evaluated the potential use of clone 9G8A for doping control purposes. While 9G8A showed lower sensitivity than AE7A5 (ca 45% on isoelectric focusing (IEF)-polyacrylamide gel electrophoresis (PAGE), ca 40% on sodium dodecyl sulfate (SDS)- and sarcosyl (SAR)-PAGE), non-specific binding of the five proteins was not observed. The cross-reactivity of AE7A5 can be overcome by immunoaffinity purification of EPO before electrophoresis and Western blotting. Similar to AE7A5, clone 9G8A is also suited for Western double-blotting. Copyright © 2016 John Wiley & Sons, Ltd.

Detection by LC-MS/MS of HIF stabilizer FG-4592 used as a new doping agent: Investigation on a positive case

Stabilizing the labile factor HIF (hypoxia inducible factor) for therapeutic use has led to the development of various molecules by pharmaceutical companies. These HIF stabilizers show promising erythropoiesis stimulating capacities and are of great interest for patients with chronical kidney disease and anemia. Amongst them FG-4592 from FibroGen is now under phase 3 of clinical studies. While this drug is still under investigation, a parallel market already allows to buy this product, which could be tempting for some athletes willing to increase their performances. To avoid such a use for doping purpose, WADA has listed HIF stabilizers and FG-4592 in particular as prohibited substances since 2011 and some anti-doping laboratories have developed a technique of identification of FG-4592 in urine. Here, we described the first case ever identified by an anti-doping laboratory of an athlete using FG-4592. Detection and confirmation in urinary samples was performed by LC-MS/MS. In addition, potential indirect markers erythropoietin (EPO) and hematological parameters followed in the Athlete Biological Passport (ABP) were analyzed during and after the period of use but showed no profound alterations. Only ABPS (abnormal blood profile score) reached (but did not exceed) the upper limit proposed by the ABP adaptive model just after the period of use of FG-4592. Altogether this case sends a warning for anti-doping laboratories which now must strengthen surveillance on HIF stabilizers and develop sensitive methods of detection for this new class of drugs.

Site-specific qualitative and quantitative analysis of the N- and O-glycoforms in recombinant human erythropoietin

Recombinant human erythropoietin (rhEPO) has been extensively used as a pharmaceutical product for treating anemia. Glycosylation of rhEPO affects the biological activity, immunogenicity, pharmacokinetics, and in-vivo clearance rate of rhEPO. Characterization of the glycosylation status of rhEPO is of great importance for quality control. In this study, we established a fast and comprehensive approach for reliable characterization and relative quantitation of rhEPO glycosylation, which combines multiple-enzyme digestion, hydrophilic-interaction chromatography (HILIC) enrichment of glycopeptides, and tandem mass spectrometry (MS) analysis. The N-linked and O-linked intact glycopeptides were analyzed with high-resolution and high-accuracy (HR-AM) mass spectrometry using an Orbitrap. In total, 74 intact glycopeptides from four glycosylation sites at N24, N38, N83, and O126 were identified, with the simultaneous determination of peptide sequences and glycoform compositions. The extracted ion chromatograms based on the HR-AM data enabled relative quantification of glycoforms. Our results could be extended to quality control of rhEPO or could help establish detection approaches for glycosylation of other proteins.

Blood doping: risks to athletes' health and strategies for detection

Blood doping has been defined as the misuse of substances or certain techniques to optimize oxygen delivery to muscles with the aim to increase performance in sports activities. It includes blood transfusion, administration of erythropoiesis-stimulating agents or blood substitutes, and gene manipulations. The main reasons for the widespread use of blood doping include: its availability for athletes (erythropoiesis-stimulating agents and blood transfusions), its efficiency in improving performance, and its difficult detection. This article reviews and discusses the blood doping substances and methods used for in sports, the adverse effects related to this practice, and current strategies for its detection.

A modified procedure based on a vacuum-driven blotting system for the detection of erythropoietin and its analogs

Background: The intake of erythropoietins as performance-enhancing drugs is banned in sport. The current method for their detection is based on advanced electrophoretic techniques (IEF-PAGE and SDS-PAGE/sarcosyl-PAGE) with double-blotting and chemiluminescence detection, requiring at least 2.5 days to be completed. Methodology & Results: The proposed procedure, based on vacuum-driven blotting technology, drastically reduces the time necessary to complete the analysis, while still fulfilling the criteria of the World Anti-Doping Agency. Validation was carried out on urine samples spiked with different recombinant erythropoietins, as well as on urine samples obtained following controlled excretion studies and on anonymized urine samples from antidoping tests. Conclusion: The proposed approach, allowing a faster turnaround time, could be very advantageous on the occasion of major sport international events (i.e., Olympic Games).

Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement

Despite the high prevalence of performance-enhancing drug (PED) use, media attention has focused almost entirely on PED use by elite athletes to illicitly gain a competitive advantage in sports, and not on the health risks of PEDs. There is a widespread misperception that PED use is safe or that adverse effects are manageable. In reality, the vast majority of PED users are not athletes but rather nonathlete weightlifters, and the adverse health effects of PED use are greatly underappreciated. This scientific statement synthesizes available information on the medical consequences of PED use, identifies gaps in knowledge, and aims to focus the attention of the medical community and policymakers on PED use as an important public health problem. PED users frequently consume highly supraphysiologic doses of PEDs, combine them with other PEDs and/or other classical drugs of abuse, and display additional associated risk factors. PED use has been linked to an increased risk of death and a wide variety of cardiovascular, psychiatric, metabolic, endocrine, neurologic, infectious, hepatic, renal, and musculoskeletal disorders. Because randomized trials cannot ethically duplicate the large doses of PEDs and the many factors associated with PED use, we need observational studies to collect valid outcome data on the health risks associated with PEDs. In addition, we need studies regarding the prevalence of PED use, the mechanisms by which PEDs exert their adverse health effects, and the interactive effects of PEDs with sports injuries and other high-risk behaviors. We also need randomized trials to assess therapeutic interventions for treating the adverse effects of PEDs, such as the anabolic-androgen steroid withdrawal syndrome. Finally, we need to raise public awareness of the serious health consequences of PEDs.

Detection of peptidic erythropoiesis-stimulating agents in sport

Detection methods for erythropoiesis-stimulating agents in sport can be classified into direct and indirect approaches. Direct methods comprise electrophoretic techniques (isoelectric focusing (IEF-), sodium-dodecylsulfate (SDS-), sarcosyl (SAR-) polyacrylamide gel-electrophoreses (-PAGE)), ELISAs and mass spectrometric methods. The haematological module of the Athlete Biological Passport is currently the only applied indirect approach. Newer developments include a mass spectrometric test for peginesatide, sequential exoglycosidase digestion of ertythropoietin (EPO) combined with electrophoresis (SDS/SAR-PAGE), a dipstick method (MAIIA), and a study on the differences in sialic acid O-acetylation of tryptic EPO O-glycopeptides. The focus of this article is on direct detection methods.

Differences in sialic acid O-acetylation between human urinary and recombinant erythropoietins: a possible mass spectrometric marker for doping control

Development of a mass spectrometric method for the unambiguous detection of doping with recombinant human erythropoietins (rhEPO) has been attempted for many years. Unfortunately, progress in this field was hampered by the unavailability of highly purified human endogenous EPOs (urinary[uhEPO], serum/plasma EPO)--a prerequisite for generating detailed mass spectrometric glycosylation data necessary for revealing significant differences between uhEPO and rhEPOs. The paper presents the worldwide first analytical data on purified human urinary EPO generated with a high resolution high accuracy mass spectrometer (LTQ-Orbitrap). The focus is on the tryptic O-glycopeptide (E117-R131) and its degree of sialic acid O-acetylation. Data are compared with results obtained from 40 rhEPO pharmaceuticals. It could be demonstrated that the O-glycopeptide of uhEPO (ca 100 IU) contains only trace amounts of mono-acetylated mono-and di-sialylated O-glycans but no other O-acetylated structures and in this respect significantly differs from all rhEPOs. Moreover, Dynepo--a rhEPO previously thought to be not O-acetylated--also contains small amounts of O-acetylations within the O-glycan structure. The results might be useful for anti-doping purposes as well as the development of EPO pharmaceuticals with closer structural similarity to the endogenous hormone.

Gel electrophoretic methods for the analysis of biosimilar pharmaceuticals using the example of recombinant erythropoietin

Due to their versatility and cost-effectiveness, gel electrophoretic methods provide an important set of tools for the analysis of therapeutic proteins. As an increasing number of biosimilar pharmaceuticals are entering the market, techniques are required that allow reliable demonstration of comparability of these products with the reference products. Isoelectric focusing, SDS-PAGE, native PAGE and 2D electrophoresis (2D-PAGE) have been frequently applied for this purpose. Supplementary techniques are fluorophore-assisted carbohydrate electrophoresis and sarcosyl-PAGE. Of additional importance is the comparison of recombinant with endogenously synthesized glycoproteins. Reagent array analysis combined with SDS-PAGE and western blotting proved especially useful for this purpose. As an example for the application of these methods, the analysis of recombinant originator erythropoietins and some of their biosimilar counterparts is described.

Mass spectrometric analysis of EPO IEF-PAGE interfering substances in nitrile examination gloves

Direct detection of doping with recombinant erythropoietins (rhEPO) is accomplished by isoelectric focusing (IEF) or sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE). In a recent publication, Lasne et al. (Electrophoresis 2011, 32, 1444) showed that improper use of nitrile examination gloves during sample collection, sample preparation, and IEF-PAGE may lead to distorted or absent EPO IEF-profiles. In order to clarify which substances are responsible for this observation, a mass spectrometric study on water extractable compounds found in nitrile gloves was performed. Several substance classes were shown to be present, among them polyethylene glycols (PEG), anionic and nonionic surfactants, as well as alcohol ethoxylates and plasticizers. It could be demonstrated that alkylbenzenesulfonates, the main category of detectable anionic detergents, and among them sodium dodecylbenzenesulfonate (SDBS) and its homologs, are the prime reason for the interference of nitrile gloves with EPO IEF-PAGE.

Detection of EPO-Fc fusion protein in human blood: screening and confirmation protocols for sports drug testing

The neonatal Fc receptor (FcRn) has been under investigation for several years as a pharmaceutical drug target. Clinical studies have shown that fusion proteins consisting of human recombinant erythropoietin (rhEPO) and the Fc-part of IgG can be transported after pulmonary administration via FcRn across the airway epithelium to the blood stream. So far, no clinically approved pharmaceutical formulation of EPO-Fc is available. Since various forms of recombinant erythropoietins have been frequently misused by athletes as performance-enhancing agents, EPO-Fc might play a similar role in sports in the future. In order to investigate the detectability of EPO-Fc in human blood, different strategies were tested and developed. Only two of them fulfilled the necessary requirements regarding sensitivity and specificity. A rapid protocol useful for screening purposes first enriches EPO-Fc from human serum via high capacity protein A beads and subsequently detects EPO-Fc in the eluate with a commercial EPO ELISA kit. The limit of detection (LOD) of the method is about 5 pg (45 amol) EPO-Fc and is independent of the serum volume used. For screening and/or confirmation purposes a second protocol was evaluated, which consists of a fast EPO immunopurification step followed by sodium dodecyl sulfate or sarcosyl polyacrylamide gel electrophoresis (SDS-PAGE, SAR-PAGE) and Western double-blotting with chemiluminescence detection - a method already established in routine EPO anti-doping control. The latter strategy allows the detection of EPO-Fc in serum together with all other recombinant erythropoietins and with an identical LOD (5 pg/45 amol) as for the rapid screening protocol.