Blood doping and its detection

Cobalt Serum Level as a Biomarker of Cause-Specific Survival among Prostate Cancer Patients

Prostate cancer is the most common cancer diagnosed in men and the second leading cause of death in male cancer patients. The WHO suggests that cobalt is involved in the carcinogenesis of prostate cancer. There are, however, no studies associating cobalt levels and prostate cancer patient survival. In this study, 261 Polish prostate cancer (n = 261) patients were recruited into a prospective cohort between 2009 and 2015. Serum cobalt levels were measured using ICP-MS after prostate cancer diagnosis and before treatment. All study participants were assigned into quartiles (QI-QIV) based on the distribution of serum cobalt levels among censored patients. Univariable and multivariable COX regression models were used to calculate hazard ratios (HRs) for each serum cobalt level quartile. We found a significant relationship between high serum cobalt levels and poor prostate cancer patient total survival (HR = 2.60; 95% CI: 1.17-5.82; p = 0.02). In relation to prostate cancer patients who died as a result of other non-cancer causes, the association with high levels of cobalt was even stronger (HR = 3.67; 95% CI: 1.03-13.00; p = 0.04). The impact of high serum cobalt levels on overall survival of prostate cancer-specific-related deaths was not statistically significant.

Erythropoietin: A Personal Alice in Wonderland Trip in the Shadow of the Giants

The identification of the hormone erythropoietin (EPO), which regulates red blood cell production, and its development into a pharmaceutical-grade product to treat anemia has been not only a herculean task but it has also been the first of its kind. As with all the successes, it had "winners" and "losers", but its history is mostly told by the winners who, over the years, have published excellent scientific and divulgate summaries on the subject, some of which are cited in this review. In addition, "success" is also due to the superb and dedicated work of numerous "crew" members, who often are under-represented and under-recognized when the story is told and often have several "dark sides" that are not told in the polished context of most reviews, but which raised the need for the development of the current legislation on biotherapeutics. Although I was marginally involved in the clinical development of erythropoietin, I have known on a personal basis most, if not all, the protagonists of the saga and had multiple opportunities to talk with them on the drive that supported their activities. Here, I will summarize the major steps in the development of erythropoietin as the first bioproduct to enter the clinic. Some of the "dark sides" will also be mentioned to emphasize what a beautiful achievement of humankind this process has been and how the various unforeseen challenges that emerged were progressively addressed in the interest of science and of the patient's wellbeing.

Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia

Sex differences in physiological responses to various stressors, including exercise, have been well documented. However, the specific impact of these differences on exposure to hypoxia, both at rest and during exercise, has remained underexplored. Many studies on the physiological responses to hypoxia have either excluded women or included only a limited number without analyzing sex-related differences. To address this gap, this comprehensive review conducted an extensive literature search to examine changes in physiological functions related to oxygen transport and consumption in hypoxic conditions. The review encompasses various aspects, including ventilatory responses, cardiovascular adjustments, hematological alterations, muscle metabolism shifts, and autonomic function modifications. Furthermore, it delves into the influence of sex hormones, which evolve throughout life, encompassing considerations related to the menstrual cycle and menopause. Among these physiological functions, the ventilatory response to exercise emerges as one of the most sex-sensitive factors that may modify reactions to hypoxia. While no significant sex-based differences were observed in cardiac hemodynamic changes during hypoxia, there is evidence of greater vascular reactivity in women, particularly at rest or when combined with exercise. Consequently, a diffusive mechanism appears to be implicated in sex-related variations in responses to hypoxia. Despite well-established sex disparities in hematological parameters, both acute and chronic hematological responses to hypoxia do not seem to differ significantly between sexes. However, it is important to note that these responses are sensitive to fluctuations in sex hormones, and further investigation is needed to elucidate the impact of the menstrual cycle and menopause on physiological responses to hypoxia.

Determinants and reference values for blood volume and total hemoglobin mass in women and men

Blood volume (BV) is an important clinical parameter and is usually reported per kg of body mass (BM). When fat mass is elevated, this underestimates BV/BM. One aim was to study if differences in BV/BM related to sex, age, and fitness would decrease if normalized to lean body mass (LBM). The analysis included 263 women and 319 men (age: 10-93 years, body mass index: 14-41 kg/m2 ) and 107 athletes who underwent assessment of BV and hemoglobin mass (Hbmass ), body composition, and cardiorespiratory fitness. BV/BM was 25% lower (70.3 ± 11.3 and 80.3 ± 10.8 mL/kgBM ) in women than men, respectively, whereas BV/LBM was 6% higher in women (110.9 ± 12.5 and 105.3 ± 11.2 mL/kgLBM ). Hbmass /BM was 34% lower (8.9 ± 1.4 and 11.5 ± 11.2 g/kgBM ) in women than in men, respectively, but only 6% lower (14.0 ± 1.5 and 14.9 ± 1.5 g/kgLBM )/LBM. Age did not affect BV. Athlete's BV/BM was 17.2% higher than non-athletes, but decreased to only 2.5% when normalized to LBM. Of the variables analyzed, LBM was the strongest predictor for BV (R2  = .72, p < .001) and Hbmass (R2  = .81, p < .001). These data may only be valid for BV/Hbmass when assessed by CO re-breathing. Hbmass /LBM could be considered a valuable clinical matrix in medical care aiming to normalize blood homeostasis.

Prediction of plasma volume and total hemoglobin mass with machine learning

Hemoglobin concentration ([Hb]) is used for the clinical diagnosis of anemia, and in sports as a marker of blood doping. [Hb] is however subject to significant variations mainly due to shifts in plasma volume (PV). This study proposes a newly developed model able to accurately predict total hemoglobin mass (Hbmass) and PV from a single complete blood count (CBC) and anthropometric variables in healthy subject. Seven hundred and sixty-nine CBC coupled to measures of Hbmass and PV using a CO-rebreathing method were used with a machine learning tool to calculate an estimation model. The predictive model resulted in a root mean square error of 33.2 g and 35.6 g for Hbmass, and 179 mL and 244 mL for PV, in women and men, respectively. Measured and predicted data were significantly correlated (p < 0.001) with a coefficient of determination (R2 ) ranging from 0.76 to 0.90 for Hbmass and PV, in both women and men. The Bland-Altman bias was on average 0.23 for Hbmass and 4.15 for PV. We herewith present a model with a robust prediction potential for Hbmass and PV. Such model would be relevant in providing complementary data in contexts such as the epidemiology of anemia or the individual monitoring of [Hb] in anti-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.

Metabolomic Profiling of Recombinant Erythropoietin (rHuEpo) in Trained Caucasian Athletes

OBJECTIVE

Recombinant human erythropoietin (rHuEpo) is prohibited by the World Anti-Doping Agency but remains the drug of choice for many cheating athletes wishing to evade detection using current methods. The aim of this study was to identify a robust metabolomics signature of rHuEpo using an untargeted approach in blood (plasma and serum) and urine.

DESIGN

Longitudinal study.

SETTING

University of Glasgow.

PARTICIPANTS

Eighteen male participants regularly engaged in predominantly endurance-based activities, such as running, cycling, swimming, triathlon, and team sports, were recruited.

INTERVENTIONS

Each participant received 50 IU·kg -1 body mass of rHuEpo subcutaneously every 2 days for 4 weeks. Samples were collected at baseline, during rHuEpo administration (over 4 weeks) and after rHuEpo administration (week 7-10). The samples were analyzed using hydrophilic interaction liquid chromatography mass spectrometry.

MAIN OUTCOME MEASURES

Significant metabolic signatures of rHuEpo administration were identified in all biofluids tested in this study.

RESULTS

Regarding metabolomics data, 488 plasma metabolites, 694 serum metabolites, and 1628 urinary metabolites were identified. Reproducible signatures of rHuEpo administration across all biofluids included alterations of pyrimidine metabolism (orotate and dihydroorotate) and acyl-carnitines (palmitoyl-carnitine and elaidic carnitine), metabolic pathways that are associated with erythropoiesis or erythrocyte membrane function, respectively.

CONCLUSIONS

Preliminary metabolic signatures of rHuEpo administration were identified. Future studies will be required to validate these encouraging results in independent cohorts and with orthogonal techniques, such as integration of our data with signatures derived from other "omics" analyses of rHuEpo administration (eg, transcriptomics).

Progress in the Detection of Erythropoietin in Blood, Urine, and Tissue

Detection of erythropoietin (Epo) was difficult until a method was developed by the World Anti-Doping Agency (WADA). WADA recommended the Western blot technique using isoelectric focusing (IEF)-PAGE to show that natural Epo and injected erythropoiesis-stimulating agents (ESAs) appear in different pH areas. Next, they used sodium N-lauroylsarcosinate (SAR)-PAGE for better differentiation of pegylated proteins, such as epoetin β pegol. Although WADA has recommended the use of pre-purification of samples, we developed a simple Western blotting method without pre-purification of samples. Instead of pre-purification, we used deglycosylation of samples before SDS-PAGE. The double detection of glycosylated and deglycosylated Epo bands increases the reliability of the detection of Epo protein. All of the endogenous Epo and exogenous ESAs shift to 22 kDa, except for Peg-bound epoetin β pegol. All endogenous Epo and exogenous ESAs were detected as 22 kDa deglycosylated Epo by liquid chromatography/mass spectrum (LC/MS) analysis. The most important factor for the detection of Epo is the selection of the antibody against Epo. WADA recommended clone AE7A5, and we used sc-9620. Both antibodies are useful for the detection of Epo protein by Western blotting.

CRISPR/deadCas9-based high-throughput gene doping analysis (HiGDA): A proof of concept for exogenous human erythropoietin gene doping detection

A genetic approach targeted toward improving athletic performance is called gene doping and is prohibited by the World Anti-Doping Agency. Currently, the clustered regularly interspaced short palindromic repeats-associated protein (Cas)-related assays have been utilized to detect genetic deficiencies or mutations. Among the Cas proteins, deadCas9 (dCas9), a nuclease-deficient mutant of Cas9, acts as a DNA binding protein with a target-specific single guide RNA. On the basis of the principles, we developed a dCas9-based high-throughput gene doping analysis for exogenous gene detection. The assay comprises two distinctive dCas9s, a magnetic bead immobilized capture dCas9 for exogenous gene isolation and a biotinylated dCas9 with streptavidin-polyHRP that enables rapid signal amplification. For efficient biotin labeling via maleimide-thiol chemistry, two cysteine residues of dCas9 were structurally validated, and the Cys574 residue was identified as an essential labeling site. As a result, we succeeded in detecting the target gene in a concentration as low as 12.3 fM (7.41 × 10⁵ copies) and up to 10 nM (6.07 × 10¹¹ copies) in a whole blood sample within 1 h with HiGDA. Assuming an exogenous gene transfer scenario, we added a direct blood amplification step to establish a rapid analytical procedure while detecting target genes with high sensitivity. Finally, we detected the exogenous human erythropoietin gene at concentrations as low as 2.5 copies within 90 min in 5 μL of the blood sample. Herein, we propose that HiGDA is a very fast, highly sensitive, and practical detection method for actual doping field in the future.

Autologous blood extracellular vesicles and specific CD4+ T-cell co-activation

Extracellular vesicles (EVs), which are generated by cell membrane budding in diverse cells, are present in variable numbers in the blood. An immunoregulatory role has been demonstrated principally for heterologous EVs, but the function of the EVs present naturally in blood remains unknown. We hypothesize that these autologous EVs might also modulate the phenotype and function of immune system cells, especially CD4⁺ T lymphocytes (TLs), as previously described for heterologous EVs. Several membranes and soluble immunoregulatory molecules were studied after the treatment of CD4⁺ TLs with autologous EVs. No direct activation was detected with autologous EVs, contrasting with the findings for heterologous EVs. However, following treatment with autologous EVs, a soluble form of CD27 (sCD27) was detected. sCD27 is strongly associated with lymphoproliferation. Autologous EVs have been shown to increase TL proliferation only after T-cell receptor (TcR) engagement due to polyclonal or specific-antigen stimulation. Our results therefore suggest that the EVs present in the blood have an immunomodulatory role different from that of heterologous EVs. These findings should be taken into account in future studies, particularly those focusing on infectious diseases, autotransfusion or doping practices.

Psychosocial aspects of sports medicine in pediatric athletes: Current concepts in the 21st century

Behavioral aspects of organized sports activity for pediatric athletes are considered in a world consumed with winning at all costs. In the first part of this treatise, we deal with a number of themes faced by our children in their sports play. These concepts include the lure of sports, sports attrition, the mental health of pediatric athletes (i.e., effects of stress, anxiety, depression, suicide in athletes, ADHD and stimulants, coping with injuries, drug use, and eating disorders), violence in sports (i.e., concepts of the abused athlete including sexual abuse), dealing with supervisors (i.e., coaches, parents), peers, the talented athlete, early sports specialization and sports clubs. In the second part of this discussion, we cover ergolytic agents consumed by young athletes in attempts to win at all costs. Sports doping agents covered include anabolic steroids (anabolic-androgenic steroids or AAS), androstenedione, dehydroepiandrostenedione (DHEA), human growth hormone (hGH; also its human recombinant homologue: rhGH), clenbuterol, creatine, gamma hydroxybutyrate (GHB), amphetamines, caffeine and ephedrine. Also considered are blood doping that includes erythropoietin (EPO) and concepts of gene doping. In the last section of this discussion, we look at disabled pediatric athletes that include such concepts as athletes with spinal cord injuries (SCIs), myelomeningocele, cerebral palsy, wheelchair athletes, and amputee athletes; also covered are pediatric athletes with visual impairment, deafness, and those with intellectual disability including Down syndrome. In addition, concepts of autonomic dysreflexia, boosting and atlantoaxial instability are emphasized. We conclude that clinicians and society should protect our precious pediatric athletes who face many challenges in their involvement with organized sports in a world obsessed with winning. There is much we can do to help our young athletes find benefit from sports play while avoiding or blunting negative consequences of organized sport activities.

Autologous Blood Doping Induced Changes in Red Blood Cell Rheologic Parameters, RBC Age Distribution, and Performance

Simple Summary

Autologous blood doping (ABD) refers to the artificial increase in circulating red blood cell (RBC) mass by sampling, storage, and transfusion of one’s own blood. It is assumed that some athletes apply this prohibited technique to improve oxygen transport capacity and thus exercise performance. The primary aim of this study was to test whether RBC rheological and associated parameters significantly change due to ABD with the consideration of whether this type of measurement might be suitable for detecting ABD. Further, it was assessed whether those changes are translated into indices of endurance performance. Eight males underwent an ABD protocol combined with several blood parameter measurements and two exercise tests (pre and post transfusion). Results of this investigation suggest a change in the distribution of age-related RBC sub-populations and altered deformability of total RBC as well as of the respective sub-populations. Further, the identified changes in RBC also appear to improve sports performance. In conclusion, these data demonstrate significant changes in hematological and hemorheological parameters, which could be of interest in the context of new methods for ABD detection. However, additional research is needed with larger and more diverse study groups to widen the knowledge gained by this study.

Abstract

Autologous blood doping (ABD) refers to the transfusion of one’s own blood after it has been stored. Although its application is prohibited in sports, it is assumed that ABD is applied by a variety of athletes because of its benefits on exercise performance and the fact that it is not detectable so far. Therefore, this study aims at identifying changes in hematological and hemorheological parameters during the whole course of ABD procedure and to relate those changes to exercise performance. Eight healthy men conducted a 31-week ABD protocol including two blood donations and the transfusion of their own stored RBC volume corresponding to 7.7% of total blood volume. Longitudinal blood and rheological parameter measurements and analyses of RBC membrane proteins and electrolyte levels were performed. Thereby, responses of RBC sub-populations—young to old RBC—were detected. Finally, exercise tests were carried out before and after transfusion. Results indicate a higher percentage of young RBC, altered RBC deformability and electrolyte concentration due to ABD. In contrast, RBC membrane proteins remained unaffected. Running economy improved after blood transfusion. Thus, close analysis of RBC variables related to ABD detection seems feasible but should be verified in further more-detailed studies.

Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity

Whether average sex differences in cardiorespiratory fitness can be mainly explained by blood inequalities in the healthy circulatory system remains unresolved. This study evaluated the contribution of blood volume (BV) and oxygen (O₂) carrying capacity to the sex gap in cardiac and aerobic capacities in healthy young individuals. Healthy young women and men (n = 28, age range = 20–43 years) were matched by age and physical activity. Echocardiography, blood pressures, and O₂ uptake were measured during incremental exercise. Left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (Q), peak O₂ uptake (VO_2peak), and BV were assessed with precise methods. The test was repeated in men after blood withdrawal and reduction of O₂ carrying capacity, reaching women’s levels. Before blood normalization, exercise cardiac volumes and output (LVEDV, SV, Q) adjusted by body size and VO_2peak (42 ± 9 vs. 50 ± 11 ml⋅min^–1⋅kg^–1, P < 0.05) were lower in women relative to men. Blood normalization abolished sex differences in cardiac volumes and output during exercise (P ≥ 0.100). Likewise, VO_2peak was similar between women and men after blood normalization (42 ± 9 vs. 40 ± 8 ml⋅min^–1⋅kg^–1, P = 0.416). In conclusion, sex differences in cardiac output and aerobic capacity are not present in experimental conditions matching BV and O₂ carrying capacity between healthy young women and men.

Erythropoietin Produces a Dual Effect on Carotid Body Chemoreception in Male Rats

Erythropoietin (EPO) regulates respiration under conditions of normoxia and hypoxia through interaction with the respiratory centers of the brainstem. Here we investigate the dose-dependent impact of EPO in the CB response to hypoxia and hypercapnia. We show, in isolated "en bloc" carotid body (CB) preparations containing the carotid sinus nerve (CSN) from adult male Sprague Dawley rats, that EPO acts as a stimulator of CSN activity in response to hypoxia at concentrations below 0.5 IU/ml. Under hypercapnic conditions, EPO did not influence the CSN response. EPO concentrations above 0.5 IU/ml decreased the response of the CSN to both hypoxia and hypercapnia, reaching complete inhibition at 2 IU/ml. The inhibitory action of high-dose EPO on the CSN activity might result from an increase in nitric oxide (NO) production. Accordingly, CB preparations were incubated with 2 IU/ml EPO and the unspecific NO synthase inhibitor (L-NAME), or the neuronal-specific NO synthase inhibitor (7NI). Both NO inhibitors fully restored the CSN activity in response to hypoxia and hypercapnia in presence of EPO. Our results show that EPO activates the CB response to hypoxia when its concentration does not exceed the threshold at which NO inhibitors masks EPO's action.

Effects of circadian variation, lifestyle and environment on hematological parameters: A narrative review

The complete blood count (CBC) is the most widely prescribed laboratory test. It plays a key role in screening, diagnosing, and monitoring a variety of medical disorders. Preanalytical and analytical variables are responsible for more than 50% of laboratory errors that may lead to spurious CBC results. The effects of blood sampling, transport, storage, and analytical errors on hematological parameters have been well described. Circadian variation and changes in lifestyle and environment can also affect blood cells. It has been extensively studied in the past, but highly variable methodology and the presence of confounding factors have provided scattered and inconsistent results. We have investigated the literature to define the impact of circadian variation, modification of the sleep-wake cycle, acute and chronic exercise, eating habits, alcohol, tobacco, drugs of abuse, high-altitude, heat/cold exposure, and air pollution on CBC results. The affected cell type along with the intensity and duration of changes are detailed for each condition. We aim at providing a comprehensive overview of which situations may induce clinically significant changes and have to be taken into account by healthcare professionals before considering a hematological parameter as pathological and requesting complementary tests.

Measurement of Immature Reticulocytes in Dried Blood Spots by Mass Spectrometry

BACKGROUND

Immature reticulocytes (IRC) are the first cells to respond to changes in erythropoiesis. For antidoping applications, measurement of IRC may improve detection of blood doping practices. Unfortunately, this small cell population has limited stability in liquid blood samples and is difficult to measure with optimal precision. We developed a method to measure 3 IRC membrane proteins in dried blood spots (DBS) to monitor changes in erythropoiesis.

METHODS

DBS spots were washed with buffers to remove soluble proteins, membrane proteins remaining in the spot were digested with trypsin, and one peptide for each protein was measured by LC-MS/MS. IRC protein concentration was determined using a DBS single point calibrator.

RESULTS

Intraassay precision for IRC proteins was between 5%-15%. IRC proteins were stable in DBS for 29 days at room temperature. In a longitudinal study of 25 volunteers, the mean intraindividual variation for 3 IRC proteins was 17%, 20%, and 24% from capillary blood DBS. In comparison, the mean longitudinal variation for IRC counts measured on an automated hematology analyzer was 38%. IRC protein concentration from capillary blood DBS correlated well with venous blood DBS protein concentrations.

CONCLUSIONS

Measurement of IRC proteins in DBS samples provides a method to measure changes in erythropoiesis with improved analytical sensitivity, stability, and precision. When combined with the inherent advantages of capillary blood collection in the field, this method may substantially improve the detection of blood doping practices.

A hazard evaluation of the reproductive/developmental toxicity of cobalt in medical devices

Cobalt (Co) is an essential element with human exposure occurring from the diet, supplement ingestion, occupational sources, and medical devices. The European Chemical Agency (ECHA) recently voted to classify Co metal as a Reproductive Hazard Category 1B; presumed human reproductive toxicant due to adverse testicular effects in male rodents. A weight of evidence evaluation of the preclinical reproductive and developmental toxicity studies and available clinical data was performed to critically evaluate the relevance of this proposed classification for Co in medical devices. Reproductive responses to Co are limited to the male testes and sperm function following high systemic exposure in rodents, only at Co concentrations/doses that result in overt toxicity (i.e., above the maximum tolerable dose (MTD)). The potential mechanisms of Co reproductive/developmental toxicity, including its indirect mode of action in the testes and relevance to humans, are discussed. The available preclinical and clincial evidence suggests that it would be more appropriate to classify Co as a Reproductive Hazard Category 2 compound: suspected human reproductive toxicant and, in the case of Co-containing medical devices, it should not be considered a reproductive hazard.

Identification of Hypoxia-inducible factor (HIF) stabilizer roxadustat and its possible metabolites in thoroughbred horses for doping control

Hypoxia-inducible factor (HIF) stabilizer belongs to a novel class of pharmacologically active substances, which are capable of inducing the endogenous erythropoietic system. The transcriptional activator HIF has been shown to significantly increase blood hemoglobin and is well set for the treatment of anemia resulting from chronic kidney disease. This research work reports a comprehensive study of the most popular HIF stabilizer roxadustat and its metabolites in thoroughbred horse urine after oral administration. The plausible structures of the detected metabolites were postulated using liquid chromatography-high-resolution mass spectrometry. Under the experimental condition 13 metabolites (7 phase I, 1 phase II, and 5 conjugates of phase I metabolism) were positively detected (M1-M13). The major phase I metabolites identified were formed by hydroxylation. Dealkylated and hydrolyzed phase I metabolites were also observed in this study. In phase II, a glucuronic acid conjugate of roxadustat was detected as the major metabolite. The sulfonic acid conjugates were observed to be formed from phase I metabolites. The characterized in vivo metabolites can potentially serve as target analytes for doping control analysis; hence, the result is an important tool for assessing its use and abuse in competitive sport.

Metabolic studies of hypoxia-inducible factor stabilisers IOX2, IOX3 and IOX4 (in vitro) for doping control

The transcriptional activator hypoxia-inducible factor (HIF) is a vital arbitrator in the performance of cellular responses lacking oxygen supply in aerobic organisms. Because these compounds are capable of enhancing the organism's capacity for molecular oxygen transport, they possess great potential for abuse as a performance-enhancing agent in sports. A comprehensive study of the metabolic conversion of the most popular HIF stabilisers such as IOX2, IOX3 and IOX4 using equine liver microsomes (in vitro) is reported. The parents and their metabolites were identified and characterised by liquid chromatography-mass spectrometry in negative ionisation mode using a QExactive high-resolution mass spectrometer. Under the current experimental condition, a total of 10 metabolites for IOX2 (three phase I and seven phase II), nine metabolites for IOX3 (four phase I and five phase II) and five metabolites for IOX4 (three phase I and two phase II) were detected. The outcome of the present study is as follows: (1) all the three IOX candidates are prone to oxidation, results in subsequent monohydroxylated, and some dihydroxylated metabolites. (2) Besides oxidation, there is a possibility of hydrolysis and de-alkylation, which results in corresponding carboxylic acid and amide, respectively. (3) The glucuronide and sulphate conjugate of the parent drugs as well as the monohydroxylated analogues were observed in this study. The characterised in vitro metabolites can potentially serve as target analytes for doping control analysis.

Induction of erythroferrone in healthy humans by micro-dose recombinant erythropoietin or high-altitude exposure

The erythropoietin (Epo)-erythroferrone (ERFE)-hepcidin axis coordinates erythropoiesis and iron homeostasis. While mouse studies have established that Epo-induced ERFE production represses hepcidin synthesis by inhibiting hepatic BMP/SMAD signaling, evidence for the role of ERFE in humans is limited. To investigate the role of ERFE as a physiological erythroid regulator in humans, we conducted two studies. First, 24 males were given six injections of saline (placebo), recombinant Epo (rhEpo) at a dose of 20 IU/kg (micro-dose) or rhEpo at 50 IU/kg (low dose). Second, we quantified ERFE in 22 subjects exposed to high altitude (3800 m) for 15 h. In the first study, total hemoglobin mass (Hbmass) increased after low- but not after micro-dose injections, when compared to the mass after placebo injections. Serum ERFE levels were enhanced by rhEpo, remaining higher than after placebo for 48 h (micro-dose) or 72 h (low-dose) after injections. Conversely, hepcidin levels decreased when Epo and ERFE rose, before any changes in serum iron parameters occurred. In the second study, serum Epo and ERFE increased at high altitude. The present results demonstrate that in healthy humans ERFE responds to slightly increased Epo levels not associated with Hbmass expansion and downregulates hepcidin in an apparently iron-independent way. Notably, ERFE flags micro-dose Epo, thus holding promise as a novel biomarker of doping.

On-Glass Integrated SU-8 Waveguide and Amorphous Silicon Photosensor for On-Chip Detection of Biomolecules: Feasibility Study on Hemoglobin Sensing

An optoelectronic, integrated system-on-glass for on-chip detection of biomolecules is here presented. The system’s working principle is based on the interaction, detected by a hydrogenated amorphous silicon photosensor, between a monochromatic light travelling in a SU-8 polymer optical waveguide and the biological solution under analysis. Optical simulations of the waveguide coupling to the thin-film photodiode with a specific design were carried out. A prototype was fabricated and characterized showing waveguide optical losses of about 0.6 dB/cm, a photodiode shot noise current of about 2.5 fA/Hz and responsivity of 495 mA/W at 532 nm. An electro-optical coupling test was performed on the fabricated device to validate the system. As proof of concept, hemoglobin was studied as analyte for a demonstration scenario, involving optical simulations interpolated with experimental data. The calculated detection limit of the proposed system for hemoglobin concentration in aqueous solution is around 100 ppm, in line with colorimetric methods currently on the market. These results show the effectiveness of the proposed system in biological detection applications and encourage further developments in implementing these kinds of devices in the biomedical field.

Cobalt-containing dust exposures: Prediction of whole blood and tissue concentrations using a biokinetic model

Biokinetic models estimating cobalt (Co) tissue burden can help assess the potential for systemic effects. Such models, however, have not been used to estimate remote tissue concentrations associated with inhalation exposure to Co-containing dust in general environments, work spaces, or animal toxicity tests. We have therefore updated a Co biokinetic model previously developed for oral dosing to include the inhalation pathway by incorporating the International Commission on Radiological Protection (ICRP) Human Respiratory Tract Model. Further, data from animal studies allowed for characterization of testes Co tissue concentration supplementing previous predictions for the liver, heart and blood. Reasonable agreement (within a factor of two) was found between modeled and measured blood, liver, testes and tissue concentrations when animal doses were modeled using human equivalent concentrations to account for species differences in regional lung deposition. We applied the updated model to occupational inhalation exposure scenarios, and found that upper-bound plausible human systemic body burden associated with Co ingestion is much higher than the burden associated with Co inhalation. Chronic ingestion of Co at a previously proposed oral reference dose (RfD) of 0.03 mg/kg-day resulted in predicted tissue levels of 22-54 μg/L (blood), 0.05-0.1 μg/g (heart), 0.01-0.02 μg/g (testes), and 0.2-0.5 μg/g (liver), which were at least 5-fold more than the systemic burden associated with various Co inhalation occupational exposure limits (OELs) of 0.1 mg/m³ or less (for 8 h/d and 5 d/w). Overall, our analysis indicated that Co-metal or dust induced systemic health effects, including myocardial damage, are unlikely for the inhalation pathway when personal exposures levels are below concentrations associated with local respiratory effects such as pulmonary fibrosis.

Single-cell modeling of routine clinical blood tests reveals transient dynamics of human response to blood loss

Low blood count is a fundamental disease state and is often an early sign of illnesses including infection, cancer, and malnutrition, but our understanding of the homeostatic response to blood loss is limited, in part by coarse interpretation of blood measurements. Many common clinical blood tests actually include thousands of single-cell measurements. We present an approach for modeling the unsteady-state population dynamics of the human response to controlled blood loss using these clinical measurements of single-red blood cell (RBC) volume and hemoglobin. We find that the response entails (1) increased production of new RBCs earlier than is currently detectable clinically and (2) a previously unrecognized decreased RBC turnover. Both component responses offset the loss of blood. The model provides a personalized dimensionless ratio that quantifies the balance between increased production and delayed clearance for each individual and may enable earlier detection of both blood loss and the response it elicits.

Hematological Adaptations to Prolonged Heat Acclimation in Endurance-Trained Males

Heat acclimation is associated with plasma volume (PV) expansion that occurs within the first week of exposure. However, prolonged effects on hemoglobin mass (Hbmass) are unclear as intervention periods in previous studies have not allowed sufficient time for erythropoiesis to manifest. Therefore, Hbmass, intravascular volumes, and blood volume (BV)-regulating hormones were assessed with 5½ weeks of exercise-heat acclimation (HEAT) or matched training in cold conditions (CON) in 21 male cyclists [(mean ± SD) age: 38 ± 9 years, body weight: 80.4 ± 7.9 kg, VO2peak: 59.1 ± 5.2 ml/min/kg]. HEAT (n = 12) consisted of 1 h cycling at 60% VO2peak in 40°C for 5 days/week in addition to regular training, whereas CON (n = 9) trained exclusively in cold conditions (<15°C). Before and after the intervention, Hbmass and intravascular volumes were assessed by carbon monoxide rebreathing, while reticulocyte count and BV-regulating hormones were measured before, after 2 weeks and post intervention. Total training volume during the intervention was similar (p = 0.282) between HEAT (509 ± 173 min/week) and CON (576 ± 143 min/week). PV increased (p = 0.004) in both groups, by 303 ± 345 ml in HEAT and 188 ± 286 ml in CON. There was also a main effect of time (p = 0.038) for Hbmass with +34 ± 36 g in HEAT and +2 ± 33 g in CON and a tendency toward a higher increase in Hbmass in HEAT compared to CON (time × group interaction: p = 0.061). The Hbmass changes were weakly correlated to alterations in PV (r = 0.493, p = 0.023). Reticulocyte count and BV-regulating hormones remained unchanged for both groups. In conclusion, Hbmass was slightly increased following prolonged training in the heat and although the mechanistic link remains to be revealed, the increase could represent a compensatory response in erythropoiesis secondary to PV expansion.

Hematological Adaptations to Prolonged Heat Acclimation in Endurance-Trained Males

Heat acclimation is associated with plasma volume (PV) expansion that occurs within the first week of exposure. However, prolonged effects on hemoglobin mass (Hb_mass) are unclear as intervention periods in previous studies have not allowed sufficient time for erythropoiesis to manifest. Therefore, Hb_mass, intravascular volumes, and blood volume (BV)-regulating hormones were assessed with 5½ weeks of exercise-heat acclimation (HEAT) or matched training in cold conditions (CON) in 21 male cyclists [(mean ± SD) age: 38 ± 9 years, body weight: 80.4 ± 7.9 kg, VO_2peak: 59.1 ± 5.2 ml/min/kg]. HEAT (n = 12) consisted of 1 h cycling at 60% VO_2peak in 40°C for 5 days/week in addition to regular training, whereas CON (n = 9) trained exclusively in cold conditions (<15°C). Before and after the intervention, Hb_mass and intravascular volumes were assessed by carbon monoxide rebreathing, while reticulocyte count and BV-regulating hormones were measured before, after 2 weeks and post intervention. Total training volume during the intervention was similar (p = 0.282) between HEAT (509 ± 173 min/week) and CON (576 ± 143 min/week). PV increased (p = 0.004) in both groups, by 303 ± 345 ml in HEAT and 188 ± 286 ml in CON. There was also a main effect of time (p = 0.038) for Hb_mass with +34 ± 36 g in HEAT and +2 ± 33 g in CON and a tendency toward a higher increase in Hb_mass in HEAT compared to CON (time × group interaction: p = 0.061). The Hb_mass changes were weakly correlated to alterations in PV (r = 0.493, p = 0.023). Reticulocyte count and BV-regulating hormones remained unchanged for both groups. In conclusion, Hb_mass was slightly increased following prolonged training in the heat and although the mechanistic link remains to be revealed, the increase could represent a compensatory response in erythropoiesis secondary to PV expansion.

Altered erythroid-related miRNA levels as a possible novel biomarker for detection of autologous blood transfusion misuse in sport

BACKGROUND

Autologous blood transfusion (ABT) is a performance-enhancing method prohibited in sport; its detection is a key issue in the field of anti-doping. Among novel markers enabling ABT detection, microRNAs (miRNAs) might be considered a promising analytical tool.

STUDY DESIGN AND METHODS

We studied the changes of erythroid-related microRNAs following ABT, to identify novel biomarkers. Fifteen healthy trained males were studied from a population of 24 subjects, enrolled and randomized into a Transfusion (T) and a Control (C) group. Seriated blood samples were obtained in the T group before and after the two ABT procedures (withdrawal, with blood refrigerated or cryopreserved, and reinfusion), and in the C group at the same time points. Traditional hematological parameters were assessed. Samples were tested by microarray analysis of a pre-identified set of erythroid-related miRNAs.

RESULTS

Hematological parameters showed moderate changes only in the T group, particularly following blood withdrawal. Among erythroid-related miRNAs tested, following ABT a pool of 7 miRNAs associated with fetal hemoglobin and regulating transcriptional repressors of gamma-globin gene was found stable in C and differently expressed in three out of six T subjects in the completed phase of ABT, independently from blood conservation. Particularly, two or more erythropoiesis-related miRNAs within the shortlist constituted of miR-126-3p, miR-144-3p, miR-191-3p, miR-197-3p, miR-486-3p, miR-486-5p, and miR-92a-3p were significantly upregulated in T subjects after reinfusion, with a person-to-person variability but with congruent changes.

CONCLUSIONS

This study describes a signature of potential interest for ABT detection in sports, based on the analysis of miRNAs associated with erythroid features.

Cobalt chloride toxicity elicited hypertension and cardiac complication via induction of oxidative stress and upregulation of COX-2/Bax signaling pathway

Cobalt is a ferromagnetic metal with extensive industrial and biological applications. To assess the toxic effects of, and mechanisms involved in cobalt chloride (CoCl₂)-induced cardio-renal dysfunctions. Male Wistar rats were exposed orally, daily through drinking water to 0 ppm (control), 150 ppm, 300 ppm, and 600 ppm of CoCl₂, respectively. Following exposure, results revealed significant ( p < 0.05) rise in markers of oxidative stress, but decreased activities of catalase, glutathione peroxidase, glutathione-S-transferase, and reduced glutathione content in cardiac and renal tissues. There were significant increases in systolic, diastolic, and mean arterial blood pressure at the 300- and 600-ppm level of CoCl₂-exposed rats relative to the control. Prolongation of QT and QTc intervals was observed in CoCl₂ alone treated rats. Also, there were significant increases in the heart rates, and reduction in P wave, and PR duration of rats administered CoCl₂. Histopathology of the kidney revealed peritubular and periglomerular inflammation, focal glomerular necrosis following CoCl₂ exposure. Further, cyclooxygenase-2 and B-cell associated protein X expressions were upregulated in the cardiac and renal tissues of CoCl₂-exposed rats relative to the control. Combining all, results from this study implicated oxidative stress, inflammation, and apoptosis as pathologic mechanisms in CoCl₂-induced hypertension and cardiovascular complications of rats.

Combined detection of the ActRII-Fc fusion proteins Sotatercept (ActRIIA-Fc) and Luspatercept (modified ActRIIB-Fc) in serum by means of immunoaffinity purification, tryptic digestion, and LC-MS/MS

Therapeutic proteins are a continuously growing class of pharmaceuticals and comprise several drug candidates with potential performance-enhancing properties. In particular, activin receptor competitors, such as the ActRII-Fc fusion proteins Sotatercept (ActRIIA-Fc) and Luspatercept (modified ActRIIB-Fc), have the potential for being misused as doping agents in sports as they were found to inhibit negative regulators of late-stage erythropoiesis. Within this study, ammonium sulfate precipitation, immunoaffinity purification, tryptic digestion, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were employed to develop an assay for the combined detection of Sotatercept and Luspatercept in doping control serum samples. The assay was optimized, comprehensively characterized, and found to be fit-for-purpose for application to sports drug testing. It complements existing tests for ActRII-Fc fusion proteins and expands the range of available detection methods for novel protein therapeutics.

Concepts About V˙O2max and Trainability Are Context Dependent

Some individuals show little or no increase in maximal oxygen consumption (V˙O2max) in response to training programs consistent with public health guidelines. However, results from studies using more intense programs challenge the concept that some humans have limited trainability. We explore the implications of these divergent observations on the biology of trainability and propose a new set of twin studies to explore them.

Ethical Concerns in Sport: When the Will to Win Exceed the Spirit of Sport

Background: The need to advance and achieve success is deeply ingrained in human evolution. As a species, humans developed instincts that allowed them to survive and transmit their genes along generations. The will to win is an instinct that has been maintained in the species for millions of years. Sport is an activity as old as humans themselves and is subject to rules; Objective: The proposal of this work is to explore some of the most recurrent practices to achieve the athletes' goals, and the origins and historical use of methods or substances to improve performance and its regulation, as well as to review the impact of new technologies on achieving better results and to make a proposal of what actions should be takenin order to prevent bad practices; Methods: A narrative literature review of ethical sports issues and decision-making was performed in the English language; Results: Practically all behavior with regards to the theme of sports is regulated by ethical codes that must be followed by sportspersons, as well as by everyone involved in the athlete's healthcare and in the athlete's administrative, marketing, and business aspects. Notwithstanding this, winning and reaping glory implies a reward far greater than fame and fortune, which can lead to poor ethical practices in athletes, as well as in interested parties who detract from the intrinsic value of the spirit of sports. The will to win could exceed the limits of what is permitted in fair-play, like the use of prohibited methods or substances; Conclusions: In this work, we review some of the bioethical aspects ofsports. Additionally, recommendations are offered for good practices and to prevent falling into poor ethical behavior.

Changes in hemoglobin profile reflect autologous blood transfusion misuse in sports

The changes in hemoglobin (Hb) profile following autologous blood transfusion (ABT) for the first time were studied for anti-doping purposes. Twenty-four healthy, trained male subjects (aged 18‒40) were enrolled and randomized into either the transfusion (T) or control (C) groups. Blood samples were taken from the T subjects at baseline, after withdrawal and reinfusion of 450 ml of refrigerated or cryopreserved blood, and from C subjects at the same time points. Hematological variables (Complete blood count, Reticulocytes, Immature Reticulocytes Fraction, Red-cell Distribution Width, OFF-hr score) were measured. The Hb types were analyzed by high-performance liquid chromatography and the Hemoglobin Profile Index (HbPI) arbitrarily calculated. Between-group differences were observed for red blood cells and reticulocytes. Unlike C, the T group, after withdrawal and reinfusion, showed a significant trend analysis for both hematological variables (Hemoglobin concentration, reticulocytes, OFF-hr score) and Hb types (glycated hemoglobin-HbA1c, HbPI). The control charts highlighted samples with abnormal values (> 3-SD above/below the population mean) after reinfusion for hematological variables in one subject versus five subjects for HbA1c and HbPI. A significant ROC-curve analysis (area = 0.649, p = 0.015) identified a HbA1c cut-off value ≤ 2.7% associated to 100% specificity of blood reinfusion (sensitivity 25%). Hemoglobin profile changed in trained subjects after ABT, with abnormal values of HbA1c and HbPI in 42% of subjects after reinfusion. Future studies will confirm the usefulness of these biomarkers in the anti-doping field.

Erythropoietin as a performance-enhancing drug: Its mechanistic basis, detection, and potential adverse effects

Erythropoietin (EPO) is the main hormone regulating red blood cell (RBC) production. The large-scale production of a recombinant human erythropoietin (rHuEPO) by biotechnological methods has made possible its widespread therapeutic use as well as its misuse in sports. Since the marketing of the first epoetin in 1989, the development has progressed to the third-generation analogs. However, the production of rHuEPO is costly, and the frequent administration of an injectable formula is not optimal for compliance of therapeutic patients. Hence, pharmaceutical industries are currently developing alternative approaches to stimulate erythropoiesis, which might offer new candidates for doping purposes. The hypoxia inducible factors (HIF) pathway is of particular interest. The introduction of new erythropoiesis-stimulating agents (ESAs) for clinical use requires subsequent development of anti-doping methods for detecting the abuse of these substances. The detection of ESAs is based on two different approaches, namely, the direct detection of exogenous substances and the indirect detection, for which the effects of the substances on specific biomarkers are monitored. Omics technologies, such as ironomics or transcriptomics, are useful for the development of new promising biomarkers for the detection of ESAs. Finally, the illicit use of ESAs associates with multiple health risks that can be irreversible, and an essential facet of anti-doping work is to educate athletes of these risks. The aim of this review is to provide an overview of the evolution of ESAs, the research and implementation of the available detection methods, and the side effects associated with the misuse of ESAs.

Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review

Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 μg g^-1, below detectable limit (BDL) to 122.4 μg g^-1, BDL to 602 μg g^-1, 0.275 to 13,040 μg g^-1, 0.004 to 15,866 μg g^-1, 0.04 to 570.80 μg g^-1 and 0.01 to 1120 μg g^-1, respectively. Only 3.2 μg L^-1 to 7.25 mg L^-1, 0.01 μg L^-1 to 7 mg L^-1, 3.80 μg L^-1 to 6.13 mg L^-1, 135.59 μg L^-1 -11.05 mg L^-1, 0.05 μg L^-1 to 1980.34 mg L^-1, 0.012 to 3.78 μg L^-1, and 1.12 μg L^-1 to 2.32 μg L^-1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

Investigation and Management of Erythrocytosis

An absolute erythrocytosis is present when the red cell mass is greater than 125 % of the predicted value for sex and body mass. It can have a primary or secondary and congenital or acquired cause. New causes particularly congenital continue to be discovered and investigated. Investigation for the cause starts with repeat and confirmation of the raised hemoglobin and measurement of an erythropoietin level to indicate whether to pursue primary or secondary causes and then further investigations as appropriate. Management options include low dose aspirin and venesection. Specific management advice is available for certain specific clinical situations.

Gender- and Sport-Specific Associations Between Religiousness and Doping Behavior in High-Level Team Sports

Religiousness is known to be specifically associated with substance abuse, but there is an evident lack of studies investigating the association between religiousness and doping behavior as a specific type of substance abuse in athletes. This study aimed to provide evidence for possible gender- and sport-specific associations between religiousness and doping behavior among team-sport athletes of both genders. The participants were 886 athletes (21.9 ± 3.8 years of age; 352 females) involved in four sports: volleyball (n = 154; 78 females), handball (n = 206; 68 females), soccer (n = 316; 110 females) and basketball (n = 230; 96 females) from Croatia and Slovenia (all traditionally Roman Catholics). The data were collected using a previously validated structured questionnaire that examined sociodemographic, sport- and doping-related factors. In addition, religiousness was captured by the Santa Clara Strength of Religious Faith questionnaire (SCSRF). Gender-stratified simple logistic regressions were applied to determine associations between covariates and doping behavior (criterion). There was no significant difference in potential doping behavior between males and females (OR 1.06, 95 % CI 0.76-1.46), while females reported higher religiousness (SCSRF: 23.11 ± 3.23 and 25.46 ± 7.2 for males and females, respectively; t test = 1.82, p < 0.05). Younger female athletes and those with higher SCSRF score are found to be less prone to doping behavior. When models were adjusted for personal opinion about doping presence in sport and age, the SCSRF remained a significant predictor of potential doping behavior (OR 0.95, 95 % CI 0.91-0.99). For males, the belief that doping was present in sport was strongly associated with a higher likelihood of doping. Our results suggest that highly religious females involved in three of the studies sports (i.e., volleyball, handball and basketball) show a weaker tendency toward doping. Meanwhile, there is no evidence that religiousness influences doping behavior among male team-sport athletes. Therefore, sport-specific and gender-specific approach in studying possible relationships that exist between religiousness and different types of misusing substances in sport is warranted.

Optimal hematocrit in an artificial microvascular network

BACKGROUND

Higher hematocrit increases the oxygen-carrying capacity of blood but also increases blood viscosity, thus decreasing blood flow through the microvasculature and reducing the oxygen delivery to tissues. Therefore, an optimal value of hematocrit that maximizes tissue oxygenation must exist.

STUDY DESIGN AND METHODS

We used viscometry and an artificial microvascular network device to determine the optimal hematocrit in vitro. Suspensions of fresh red blood cells (RBCs) in plasma, normal saline, or a protein-containing buffer and suspensions of stored red blood cells (at Week 6 of standard hypothermic storage) in plasma with hematocrits ranging from 10 to 80% were evaluated.

RESULTS

For viscometry, optimal hematocrits were 10, 25.2, 31.9, 37.1, and 37.5% for fresh RBCs in plasma at shear rates of 3.2 or less, 11.0, 27.7, 69.5, and 128.5 inverse seconds. For the artificial microvascular network, optimal hematocrits were 51.1, 55.6, 59.2, 60.9, 62.3, and 64.6% for fresh RBCs in plasma and 46.4, 48.1, 54.8, 61.4, 65.7, and 66.5% for stored RBCs in plasma at pressures of 2.5, 5, 10, 20, 40, and 60 cm H₂ O.

CONCLUSION

Although exact optimal hematocrit values may depend on specific microvascular architecture, our results suggest that the optimal hematocrit for oxygen delivery in the microvasculature depends on perfusion pressure. Therefore, anemia in chronic disorders may represent a beneficial physiological response to reduced perfusion pressure resulting from decreased heart function and/or vascular stenosis. Our results may help explain why a therapeutically increasing hematocrit in such conditions with RBC transfusion frequently leads to worse clinical outcomes.

Biology of VO2 max: looking under the physiology lamp

In this review, we argue that several key features of maximal oxygen uptake (VO₂ max) should underpin discussions about the biological and reductionist determinants of its interindividual variability: (i) training-induced increases in VO₂ max are largely facilitated by expansion of red blood cell volume and an associated improvement in stroke volume, which also adapts independent of changes in red blood cell volume. These general concepts are also informed by cross-sectional studies in athletes that have very high values for VO₂ max. Therefore, (ii) variations in VO₂ max improvements with exercise training are also likely related to variations in these physiological determinants. (iii) All previously untrained individuals will respond to endurance exercise training in terms of improvements in VO₂ max provided the stimulus exceeds a certain volume and/or intensity. Thus, genetic analysis and/or reductionist studies performed to understand or predict such variations might focus specifically on DNA variants or other molecular phenomena of relevance to these physiological pathways.

Erythropoiesis with endurance training: dynamics and mechanisms

The purpose of the present study was to characterize the progression of red blood cell volume (RBCV) expansion and potential volumetric and endocrine regulators of erythropoiesis during endurance training (ET). Nine healthy, untrained volunteers (age = 27 ± 4 yr) underwent supervised ET consisting of 3–4 × 60 min cycle ergometry sessions per week for 8 wk. Plasma volume (PV), RBCV, and overnight fasting hematological markers were determined before and at weeks 2, 4, and 8 of ET. In addition, plasma erythropoietin (EPO), cortisol, copeptin, and proatrial natriuretic peptide concentrations were measured during a 3-h morning period at baseline and postexercise at weeks 1 and 8. PV increased from baseline (2,405 ± 335 ml) at weeks 2, 4, and 8 (+374 ± 194, +505 ± 156, and +341 ± 160 ml, respectively, P < 0.001). Increases in RBCV from baseline (1,737 ± 442 ml) were manifested at week 4 (+109 ± 114 ml, P = 0.030) and week 8 (+205 ± 109 ml, P = 0.001). Overnight fasting plasma EPO concentration increased from baseline (11.3 ± 4.8 mIU/ml) at week 2 (+2.5 ± 2.8 mIU·ml−1, P = 0.027) and returned to baseline concentration at weeks 4 and 8. Higher 3-h-postexercise EPO concentration was observed at week 1 (11.6 mIU/ml) compared with week 8 (8.4 ± 3.9 mIU/ml, P = 0.009) and baseline (9.0 ± 4.2 mIU/ml, P = 0.019). Linear relationships between EPO concentration and hematocrit (β = −56.2, P < 0.001) and cortisol (β = 0.037, P < 0.001) were detected throughout the ET intervention. In conclusion, ET leads to mild, transient increases in circulating EPO concentration, concurring with early PV expansion and lowered hematocrit, preceding gradual RBCV enhancement.

Cobalt toxicity in humans-A review of the potential sources and systemic health effects

Cobalt (Co) and its compounds are widely distributed in nature and are part of numerous anthropogenic activities. Although cobalt has a biologically necessary role as metal constituent of vitamin B₁₂, excessive exposure has been shown to induce various adverse health effects. This review provides an extended overview of the possible Co sources and related intake routes, the detection and quantification methods for Co intake and the interpretation thereof, and the reported health effects. The Co sources were allocated to four exposure settings: occupational, environmental, dietary and medical exposure. Oral intake of Co supplements and internal exposure through metal-on-metal (MoM) hip implants deliver the highest systemic Co concentrations. The systemic health effects are characterized by a complex clinical syndrome, mainly including neurological (e.g. hearing and visual impairment), cardiovascular and endocrine deficits. Recently, a biokinetic model has been proposed to characterize the dose-response relationship and effects of chronic exposure. According to the model, health effects are unlikely to occur at blood Co concentrations under 300μg/l (100μg/l respecting a safety factor of 3) in healthy individuals, hematological and endocrine dysfunctions are the primary health endpoints, and chronic exposure to acceptable doses is not expected to pose considerable health hazards. However, toxic reactions at lower doses have been described in several cases of malfunctioning MoM hip implants, which may be explained by certain underlying pathologies that increase the individual susceptibility for Co-induced systemic toxicity. This may be associated with a decrease in Co bound to serum proteins and an increase in free ionic Co²⁺. As the latter is believed to be the primary toxic form, monitoring of the free fraction of Co²⁺ might be advisable for future risk assessment. Furthermore, future research should focus on longitudinal studies in the clinical setting of MoM hip implant patients to further elucidate the dose-response discrepancies.

The optimum hematocrit

The hematocrit (Hct) determines the oxygen carrying capacity of blood, but also increases blood viscosity and thus flow resistance. From this dual role the concept of an optimum Hct for tissue oxygenation has been derived. Viscometric studies using the ratio Hct/blood viscosity at high shear rate showed an optimum Hct of 50-60% for red blood cell (RBC) suspensions in plasma. For the perfusion of an artificial microvascular network with 5-70μm channels the optimum Hct was 60-70% for high driving pressures. With lower shear rates or driving pressures the optimum Hct shifted towards lower values. In healthy, well trained athletes an increase of the Hct to supra-normal levels can increase exercise performance. These data with healthy individuals suggest that the optimum Hct for oxygen transport may be higher than the physiological range (35-40% in women, 39-50% in men). This is in contrast to clinical observations. Large clinical studies have repeatedly shown that a correction of anemia in a variety of disorders such as chronic kidney disease, heart failure, coronary syndrome, oncology, acute gastrointestinal bleeding, critical care, or surgery have better clinical outcomes when restrictive transfusion strategies are applied. Actual guidelines, therefore, recommend a transfusion threshold of 7-8 g/dL hemoglobin (Hct 20-24%) in stable, hospitalized patients. The discrepancy between the optimum Hct in health and disease may be due to factors such as decreased perfusion pressures (low cardiac output, vascular stenoses, change in vascular tone), endothelial cell dysfunction, leukocyte adhesion and others.

Gene therapy: progress and predictions

The first clinical gene delivery, which involved insertion of a marker gene into lymphocytes from cancer patients, was published 25 years ago. In this review, we describe progress since then in gene therapy. Patients with some inherited single-gene defects can now be treated with their own bone marrow stem cells that have been engineered with a viral vector carrying the missing gene. Patients with inherited retinopathies and haemophilia B can also be treated by local or systemic injection of viral vectors. There are also a number of promising gene therapy approaches for cancer and infectious disease. We predict that the next 25 years will see improvements in safety, efficacy and manufacture of gene delivery vectors and introduction of gene-editing technologies to the clinic. Gene delivery may also prove a cost-effective method for the delivery of biological medicines.