Article

Drugs for Increasing Oxygen Transport and Their Potential Use in Doping1: A Review

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Abstract

Blood oxygenation is a fundamental factor in optimising muscular activity. Enhancement of oxygen delivery to tissues is associated with a substantial improvement in athletic performance, particularly in endurance sports. Progress in medical research has led to the identification of new chemicals for the treatment of severe anaemia. Effective and promising molecules have been created and sometimes used for doping purposes. The aim of this review is to present methods, and drugs, known to be (or that might be) used by athletes to increase oxygen transport in an attempt to improve endurance capacity. These methods and drugs include: (i) blood transfusion; (ii) endogenous stimulation of red blood cell production at altitude, or using hypoxic rooms, erythropoietins (EPOs), EPO gene therapy or EPO mimetics; (iii) allosteric effectors of haemoglobin; and (iv) blood substitutes such as modified haemoglobin solutions and perfluorochemicals. Often, new chemicals are used before safety tests have been completed and athletes are taking great health risks. Such new chemicals have also created the need for new instrumental strategies in doping control laboratories, but not all of these chemicals are detectable. Further progress in analytical research is necessary.

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... The first is to stimulate the natural oxygen carrier, hemoglobin (Hb). The second way is to use other types of oxygen carriers to fill the role of Hb [10]. Athletic endurance is determined by an athlete's maximum oxygen uptake (VO 2 max); by the 1930s, it was clear that champion endurance athletes had extremely high measurements of VO 2 max [11,12]. ...
... Using this concept, altitude is used as a natural stimulus for erythropoiesis. It requires 3 to 4 weeks before a response is seen [10] and is ''legal.'' Despite a paucity of randomized, controlled studies, some form of this technique (''sleep high and train low'' or vice versa) is practiced often by elite endurance athletes. ...
... Autologous or heterologous blood transfusions were used most prevalently by athletes during the 1970s and 1980s, until the risk for blood-borne infections became more apparent. The IOC banned this practice in 1976 [10]. With the Lasne test now available, this practice has resurfaced as an option for some athletes. ...
Article
Dating back to the earliest Olympics, athletes have been searching for a performance edge. Recombinant human erythropoietin was made commercially available in 1987 to treat various diseases associated with anemia. Within a few years, elite endurance athletes capitalized on its potential as an undetectable performance-enhancing agent. Although antidoping agencies have developed a test to detect its use, there are pitfalls. More importantly, athletes continue to add more sophisticated doping practices to their armamentarium, challenging regulatory agencies, putting their health at great risk, and tainting the spirit of fair competition.
... This review will explore the ergogenic benefits associated with enhanced O 2 delivery to tissues, and the methods, risks and detection strategies for agents used in doping. For additional discussions, the reader is directed to several excellent reviews on the subject (Kazlauskas et al., 2002; Catlin et al., 2003; Gaudard et al., 2003). ...
... The short half-life of these molecules indicates that they must be infused at the time of need to derive benefit. Perfluorocarbons are useful as O 2 carriers (Gaudard et al., 2003; Lippi et al., 2006b) because emulsions of these molecules dissolve high concentrations of O 2 that can be extracted by O 2 -deprived tissues. However, unlike Hb that has a sigmoidal relationship between pO 2 and O 2 binding, PFCs have a linear one. ...
Article
Oxygen is essential for life, and the body has developed an exquisite method to collect oxygen in the lungs and transport it to the tissues. Hb contained within red blood cells (RBCs), is the key oxygen-carrying component in blood, and levels of RBCs are tightly controlled according to demand for oxygen. The availability of oxygen plays a critical role in athletic performance, and agents that enhance oxygen delivery to tissues increase aerobic power. Early methods to increase oxygen delivery included training at altitude, and later, transfusion of packed RBCs. A breakthrough in understanding how RBC formation is controlled included the discovery of erythropoietin (Epo) and cloning of the EPO gene. Cloning of the EPO gene was followed by commercial development of recombinant human Epo (rHuEpo). Legitimate use of this and other agents that affect oxygen delivery is important in the treatment of anaemia (low Hb levels) in patients with chronic kidney disease or in cancer patients with chemotherapy-induced anaemia. However, competitive sports was affected by illicit use of rHuEpo to enhance performance. Testing methods for these agents resulted in a cat-and-mouse game, with testing labs attempting to detect the use of a drug or blood product to improve athletic performance (doping) and certain athletes developing methods to use the agents without being detected. This article examines the current methods to enhance aerobic performance and the methods to detect illicit use.
... An artificial increase in plasma volume has positive effects on exercise at a submaximal level only, whereas an increase in the amount of hemoglobin from altitude training, blood-or EPO-doping mainly affects the aerobic capacity. Therefore, a stimulation of erythropoiesis through exercise at sea-level mainly affects the oxygen transport capacities which will be discussed below, whereas endurance training improves cardiac output and muscular vascularisation, as does blood-doping or EPO-doping (Gaudard et al., 2003). ...
... Such practices have been banned by the International Olympic Committee since 1990, but 18-20 athletes, mainly racing cyclists, have nonetheless died in the meantime and, in some cases, the suspicion was raised that EPO-doping might have been involved. There are, as of yet, no reliable techniques available for detecting this abuse because of the perfect homology between endogenous and rh EPO, its short plasma half-life, the late clinical manifestations of its effects and the requirement for invasive procedures, i.e. blood collection (for review see Gaudard et al., 2003 andDiamanti-Kandarakis et al., 2005). Recently, several studies have been conducted in order to define reference ranges for serum EPO and soluble transferrin receptor levels and to monitor changes in these two proteins after administration of EPO to athletes (Gareau et al., 1996(Gareau et al., , 1994Robinson et al., 2003). ...
Article
In the adult human, the kidney is the main organ for the production and release of erythropoietin (EPO). EPO is stimulating erythropoiesis by increasing the proliferation, differentiation and maturation of the erythroid precursors. In the last decades, enormous efforts were made in the purification, molecular encoding and description of the EPO gene. This led to an incredible increase in the understanding of the EPO-feedback-regulation loop at a molecular level, especially the oxygen-dependent EPO gene expression, a key function in the regulation loop. However, studies in humans at a systemic level are still very scanty. Therefore, it is the purpose of the present review to report on the main recent investigations on EPO production and release in humans under different environmental and experimental conditions, including: (i) studies on EPO circadian, monthly and even annual variations, (ii) studies in connection with short-, medium- and long-term exercise at sea-level which will be followed (iii) by studies performed at moderate and high altitude.
... An artificial increase in plasma volume has positive effects on exercise at a submaximal level only, whereas an increase in the amount of hemoglobin from altitude training, blood-or EPO-doping mainly affects the aerobic capacity. Therefore, a stimulation of erythropoiesis through exercise at sea-level mainly affects the oxygen transport capacities which will be discussed below, whereas endurance training improves cardiac output and muscular vascularisation, as does blood-doping or EPO-doping ( Gaudard et al., 2003). In general, the endurance capacity of the human species compared to other mammals and in relation to the kg body mass is exceptionally high. ...
... Such practices have been banned by the International Olympic Committee since 1990, but 18-20 athletes, mainly racing cyclists, have nonetheless died in the meantime and, in some cases, the suspicion was raised that EPO-doping might have been involved. There are, as of yet, no reliable techniques available for detecting this abuse because of the perfect homology between endogenous and rh EPO, its short plasma half-life, the late clinical manifestations of its effects and the requirement for invasive procedures, i.e. blood collection (for review see Gaudard et al., 2003 andDiamanti-Kandarakis et al., 2005). Recently, several studies have been conducted in order to define reference ranges for serum EPO and soluble transferrin receptor levels and to monitor changes in these two proteins after administration of EPO to athletes ( Gareau et al., 1996Gareau et al., , 1994Robinson et al., 2003). ...
... The use of performance-enhancing drugs (doping) can be dated back to the ancient Olympics [1], [2]. Since then athletes have used a wide range of substances including red wine, caffeine, nitroglycerin, cocaine, opiates, amphetamines, growth hormone, blood transfusions, anabolic steroids, and erythropoietin (EPO) in an effort to gain a physiological advantage [3]. Because performance-enhancing drugs compromises the idealized principles of pure competition, the World Anti-Doping Agency (WADA) was created in 1999 [4]. ...
Article
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The major cycling "Grand Tours" have shown an attenuation of performance over the last decade. This has been interpreted as circumstantial evidence that newer anti-doping strategies have reduced the use of performance-enhancing drugs. To examine this idea under more controlled conditions, speed trends for world class 5000 m, 10000 m, and marathon performances by men from 1980 to 2013 were analyzed. We obtained comprehensive records from the International Association of Athletics Federations, Association of Road Racing Statisticians, and the Track and Field All-time Performances database webpages. The top 40 performances for each event and year were selected for regression analysis. For the three distances, we noted cumulative performance improvements in the 1990s thru the mid-2000s. After the peak speed years of the mid 2000 s, there has been limited improvement in the 5000 m and 10,000 m and world records set during that time remain in place today, marking the longest period of time between new records since the early 1940s. By contrast marathon speed continues to increase and the world record has been lowered four times since 2007, including in 2013. While the speed trends for 5000 m and 10000 m track results parallel those seen in elite cycling, the marathon trends do not. We discuss a number of explanations other than improved anti-doping strategies that might account for these divergent findings.
... Because patients with kidney failure fail in EPO production, which produces dangerous anemia, EPO has been synthesized by recombinant DNA for medical uses. As with other medical advances, EPO was diverted into doping by athletes seeking a competitive edge [29]. There is a concern that a significant proportion of the EPO produced by drug companies is diverted to PED use. ...
Chapter
Nutrition plays a pivotal role in sustaining human health, extending healthy life span, enhancing sports performance, and offsetting the challenges of advancing age. As current research improves our understanding of dietary requirements in different contexts of human function, a comprehensive appraisal of the role of nutrition in human health and performance is warranted. It is this need that has inspired the current volume. This volume is divided into six thematic sections. The introductory section presents a general overview of the role of nutrition in human health. This section is a compilation of chapters reviewing nutritional prophylaxis in human health, including food exchange values, personalized nutrition and a critical assessment of antioxidants, vitamins, membrane stabilizers, minerals, herbal extracts and other nutritional supplements and their influence on human health and exercise performance. This section also addresses performance enhancement drugs and sports supplements, discussing concerns associated with the benefits and risks associated with the use of performance-enhancing supplements.
... 16 = 1760 riders in total. However, studies that attempted to roughly estimate the use of epo doping among top–level endurance–sport athletes in that era concluded that epo was used by ~3–7% of them [1,8910. Hence, the argument that performances of all 1760 riders in that era somehow came about through illicit, unnatural means is not very convincing. ...
Article
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The paper can be downloaded from: http://article.sapub.org/10.5923.j.sports.20120203.02.html#Sec3.3.3 http://www.academia.edu/1129534/Tour_Giro_and_Vuelta_Rapid_progress_in_road_cycling_performance_starts_in_the_1980s After analyzing historic records (1892-2008), El Helou et al. [1] reported a distinctive 6.38% improvement in speed in European professional road racing from 1993 onwards, a period which coincides with the years of the ‘epo epidemic’ in professional cycling. We aim to show that this improvement might be spurious, since El Helou et al. did not account for the influence of confounding variables on riders’ speed progression over time. We scrutinized archival data provided by the French Association Mémoire du Cy¬clisme [12] and assessed winning riders’ kilometers per hour (kph) and time performances, demonstrated in the Tour, Giro and Vuelta from 1903 to 2011(N = 256). We next classified these measures in ten time periods, accounting for El Helou et al.’s ‘critical’ year 1993. We further assessed the distances and brutality rates of the races, as well as the number of stages in the races and included these variables as covariates in the study, because we expected them to influence riders’ achievements. Analyses of covariance (ANCOVA) showed that the variables included in the model explained R2adj. = .89–.98 of the variation in riders’ performances. The three covariates indeed influenced riders’ performances to a greater or a lesser extent over the years. Time performances appeared to be more valid to appraise riders’ speed progression than kph performances, because the former variable is not biased by the distances of the races. After adjusting for the influence of the covariates, multiple comparisons between time periods indicated that time performances in El Helou et al.’s critical years did not significantly differ from performances displayed by riders in immediate foregoing or succeeding years. Furthermore, the 1970s appeared to be key in riders’ evolution in performance over time. We next calculated the proportional progress (%) in time performances per period as ANCOVA follow–up. Across races, we obtained an improvement of 3.18% in time performance beyond the 1990s that does not deviate from the range of expected variability in performance progress over time. Using the 1970s as a baseline, findings further showed a significant linear and curvilinear progress in time performance within and across the three Grand Tours. Inconsistent with El Helou et al.’s conclusion, however, the rapid linear progress originates in the 1980s, not in the 1990s, and gradually levels off from the 1990s onwards in all three multi–stage races. Findings strongly question opinions about the effects of the ‘epo epidemic’ on cyclists’ performances.
... An athlete's increased physiological performance caused by current drugs or possibly more powerful drugs in the future threatens that have the potential to damage the tests and contests of a variety of sports. Confirming popular belief, scientific metaanalyses of studies on performance-enhancing drugs indicate that elite athletes who use these drugs show measurable improvement in their performance (Gaudard et al. 2003). Having set aside the issue of health, I will argue that permitting pharmaceutical performance enhancers facilitates significant improvements that threaten the welldesigned tests of numerous sports. ...
Article
Scholars such as Simon (2007; 2004) and Loland (2002) as well as the authors of the World Anti-Doping Code (2001) argue that using performance-enhancing substances is unhealthy and unfairly coercive for other athletes. Critics of the anti-doping position such as Hoberman (1995), Miah et al. (2005)and Tamburrini (2007) are quick to argue that such prohibitions, even though well-intended, constitute an unjustifiable form of paternalism. However, advocates for both of these positions assume that preserving good health and, conversely, avoiding health-related harms, lie at the centre of the debate. Given the apparent stalemate in the debate over the validity of health concerns on performance-enhancing drugs, in this essay, I investigate ethical issues of 'harm-free' pharmaceutical performance enhancement. Beginning with the hypothesis that a harm-free performance-enhancing drug may be produced in the future, I ask if there would still be compelling reasons for prohibiting such a drug. I address this question by providing two arguments against allowing athletes to use pharmaceutical performance-enhancing drugs-the damage to the testing and contesting of sport and the loss of internal goods that are intrinsically satisfying. These two arguments taken together, I argue, are sufficient to sustain the prohibition of pharmaceutical performance-enhancing drugs without citing their harmful side effects.
... Због тога се ЕРО посматра као забрањена допинг метода која повећава транспорт кисеоника и капацитет спортске издржљивости. Он се користи да би се повећале спортске перформансе (Gaudard, Varlet-Marie, Bressolle, & Audran, 2003). Међународни олимпијски комитет је 1990. ...
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Hepcidin is a peptide that was discovered in 2000, it is synthesized in the liver and it goes into circulation. There are three forms of hepcidin, hepcidin-25, hepcidin-22 and hepcidin-20. The first form is the most studied and its role is the most significant. Hepcidin-25 is considered to be a major regulator of the absorption of dietary iron as well as its release from cells. It achieves its regulatory function by preventing the function of ferroportin, the major cellular iron exporter. Ferroportin is a protein whose function is to release iron from the cells on which it is located (macrophages, hepatocytes and enterocytes). Hepcidin-25 induces degradation of ferroportin, resulting in an increase in intracellular iron stores. It also reduces the absorption of iron from food and thus reduces the concentration of circulating iron. During physical activity, the concentration of hepcidin increases at an intensity of 65% VO2 max, and maximum values are reached at 90-95% VO2 max. Not only intensity, but also the volume of physical activity influence its concentration. Studies showed that hepcidin expression during physical activity is influenced by inflammation, iron status, erythropoiesis and hypoxia. It is considered one of the causes of anemia in athletes. There are potential methods for neutralizing hepcidin (monoclonal antibodies and antagonists) and reducing its expression (erythropoietin doping, which is forbidden in sport, anti-IL-6 antibodies, STAT and BMP modulators). Given its important role in iron metabolism, which is essential for the transport of oxygen in the body, it can affect sports performance. It is still the subject of many research.
... Media coverage may also play a role, although this has been prevalent since the earliest bicycle races (Musée National du Sport, 2007). Although prohibited substances have probably been used since the end of the Second World War, some major pharmacological innovations appeared at the beginning of period 4 (Diamanti- Kandaris et al., 2005;Gaudard, Varlet-Marie, Bressolle, & Audran, 2003;Juhn, 2003;Lucia, Earnest, & Arribas, 2003). However, no previous publications have included this factor when modelling road cycling performance. ...
Article
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Road cycling ranks among the most intense endurance exercises. Previous studies and mathematical models describing road cycling have not analysed performances per se. We describe the evolution of road cycling performance over the past 116 years. We studied the top ten cyclists' mean speeds in eight famous classic races and three European Grand Tours, using a previously published multi-exponential model that highlights the different progression periods of an event during the century. In addition, we measured an indicator of difficulty for the Tour de France by calculating the climbing index (i.e. the total altitude climbed over total distance). The eleven races' mean speed increased progressively from 23.13 km . h(-1) in 1892 to 41.19 +/- 2.03 km . h(-1) in 2008. Road cycling development, like other quantifiable disciplines, fits a piecewise progression pattern that follows three periods: before, between, and after the two World Wars. However, a fourth period begins after 1993, providing a speed progression of 6.38% from the third one. The Tour de France's climbing index also provided insight into a recent paradoxical relationship with speeds: when the climbing index increased, the winner's speed also increased. Our results show a major improvement (6.38%) in road cycling performance in the last 20 years and question the role of extra-physiological parameters in this recent progression.
Article
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Chapter
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Aims. – Draw up the inventory of various methods able to increase the oxygen transport by the blood and present methods and strategy of detection.Current knowledge. – Maximal oxygen uptake is the major performance limiting factor in endurance sports. Sophisticated training methods have been developed to increase this variable. On the other hand, attempts have been made to improve maximal oxygen uptake by artificial means: blood doping, administration of human recombinant erythropoietin (rhu-Epo) and, probably, by the use of a new class of therapeutic agents: the artificial oxygen carriers. All these substances and methods are prohibited by the International Olympic Committee. But, until now, the detection of the misuse of these compounds is a problem: there is no detection method for blood doping, the current test method for rhu-Epo can do false negative cases and no screening methods are performed for oxygen carriers.Points of views and plans. – Despite the emergence of the oxygen carriers, in fact easy to detect, the use of r-HuEpo seems the most efficient practice. Today there is a test to detect abuse of r-HuEpo, that’s why the cheats should have recourse to red blood cells transfusion. However concomitant injections of r-HuEpo and GH or IL-3 should use least doses and so to make the detection more difficult. Although indirect methods will be refined, this approach will likely insufficient by itself. A careful definition of an individual’s hematologic profile, the so-called “hematologic passport”, should form the basis for a more successful application of any indirect method and should disturb recourse to doping.
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The aerobic work capacity of 11 highly trained runners was studied employing a double-blind design 1) before phlebotomy (C1), 2) following restoration of normocythemia (C2), 3) after a sham reinfusion of 50 ml of saline (sham), 4) following autologous reinfusion of approximately 900 ml of freeze-preserved blood (reinfusion), and 5) upon reestablishment of control hematologic levels after erythrocythemia (C3). There were no hematologic differences among C1, C2, sham, and C3, but following reinfusion, hemoglobin was significantly elevated (15.7-16.7 g . 100 ml-1). Maximum O2 consumption (VO2max) and running time to exhaustion were significantly increased 24 h postreinfusion (5.11-5.37 l . min-1 and 7.20-9.65 min, respectively) and 7 days postreinfusion. When sham preceded reinfusion, VO2 max and time to exhaustion were the same as control. However, 16 wk postreinfusion, despite the return to normal hematologic values, VO2max remained significantly above control levels at sham and C3. These findings indicate that there is a distinct increase in VO2max following induced erythrocythemia and suggest that oxygen transport limits maximal aerobic capacity.
Article
In an attempt to enhance the therapeutic efficacy of interleukin-2 (IL-2), recombinant human IL-2 was encapsulated either in large conventional liposomes or in small (mean diameter 65 nm), unilamellar, long-circulating, extravasating liposomes [referred to as sterically stabilized liposomes (SSLs)]. The SSL-IL-2 activity was assessed in vitro and in mice in comparison with soluble IL-2, IL-2 in conventional liposomes (non-SSL-IL-2), and pegilated IL-2 (PEG-IL-2). The main observations were as follows: (a) SSLs were far better carriers than conventional liposomes with regard to encapsulation efficiency and pharmacokinetics; (b) > 85% of IL-2 biological activity was consistently encapsulated in SSLs; (c) SSL-IL-2 was much more stable than soluble IL-2 at 4 and 37 degrees C; (d) SSL-IL-2, but not ''empty'' liposomes, bound in vitro to IL-2 receptor-bearing T-cells, indicating that the domain of the cytokine molecule involved in binding to the receptor is exposed on the outer liposome membrane; (e) release of IL-2 from the liposomes was not required for its in vitro biological activity; (f) plasma half-lives (t1/2 alpha, t1/2 beta) and area under the curve (AUC) of SSL-IL-2 were 10-30 times greater than those of soluble IL-2 and similar to those of PEG-IL-2; and (g) IL-2 is released from the SSLs in vivo with a t1/2 of similar to 40 min, although the SSL-IL-2s retained their steric stabilization in the plasma for > 4 h, with little liposome accumulation in the reticuloendothelial system. These data, together with the improved immunomodulatory and antitumor activity of SSL-IL-2 in mice, suggest that SSL-IL-2 might be a therapeutic agent superior to soluble IL-2.
Article
Perfluoroctylbromide (PFOB) has been applied successfully as an oxygen carrier and a contrast agent for X-ray, computed tomography, ultrasound and Magnetic Resonance Imaging (MRI). Knowledge of the pharmacokinetics of emulsion particle uptake and elimination is critical for determining proper dose and timing of diagnostic studies. This study was intended to define major organ biodistribution and half-life as well as total body half-life as a function of dose. Determination of biodistribution and major organ half-life was achieved by administering 100% PFOB emulsion intravenously to 180 rats divided into 3 dose groups of 0.3, 0.6 & 1.0 g/kg. Each group was divided into 6 subgroups (n = 10; S male and 5 female). Each subgroup was sacrificed at either 6 or 90 min., 1,2,7, or 28 days post injection. 16 different tissue samples were collected and PFOB concentration determined by iso-octane extraction and gas chromatographic (GC) analysis. Total body half-life was determined by administering PFOB intravenously to 60 rats divided into 3 dose groups of 0.6, 1.5 & 5.0 g/kg. Each group contained 10 pairs (5 male and S female). Pairs were placed in a metabolic cage at 1, 6 & 12 hrs., 1, 2, 4, 7, 11, 16, & 21 days following PFOB infusion. The metabolic cage facilitated the seperate collection of expired air, urine & feces. PFOB was extracted from expired air by a series of iso-octane traps. PFOB losses from expired air, urine and feces were quantified by GC analysis.
Article
Theoretically, if the arterial partial oxygen pressure (PaO2) does not change, a right shift in the oxygen equilibrium curve (OEC) of hemoglobin should reduce arterial oxygen saturation, In this study we investigate,whether a right shift in the OEC of hemoglobin decreases transcutaneous oxygen saturation (Tc-SO2) following the administration of an allosteric effector, 2-[4-(((3,5-dichloroanilino)-carbonyl) methyl) phenoxy]-2-methylpropionic acid (RSR-4). The effect of RSR-4 on hemoglobin oxygen affinity was studied in four New Zealand white male rabbits. Following intraperitoneal administration of RSR-4, Tc-SO2 decreased in a dose-dependent manner. P-50 (partial oxygen pressure at 50% hemoglobin oxygen saturation) in whole blood increased as the concentration of RSR-4 increased. Tc-SO2 decreased as whole-blood affinity (1/P-50) decreased. There was no positive correlation between Tc-SO2 and PaO2. We concluded that a decrease in hemoglobin oxygen affinity following RSR-4 administration reduced arterial oxygen saturation. This decrease in the presence of an allosteric effector such as RSR-4 in vivo can be detected and monitored as a reduction in Tc-SO2.
Article
The effects of subcutaneous injections of human erythropoietin (rhEpo) on the circulatory response to submaximal and maximal exercise were studied in healthy male subjects (n=15). Hemoglobin concentration [Hb] increased from 152 g · l−1 to 169 g · l−1 and in parallel maximal aerobic power (Vo2max) increased from 4.52 to 4.88 l · min−1. There were no significant changes in heart rate, ventilation and blood lactate concentration during the exhausting run. Compared with infusion of red blood cells, there was no significant difference in the increase in Vo2max per gram increase in [Hb]. Systolic blood pressure at 200 W increased from before rhEpo treatment to afterwards. It was concluded that slow (rhEpo treatment) and acute (red blood cell reinfusion) increase of [Hb] resulted in similar increase in Vo2max.
Article
The approval of Fluosol, a fluorocarbon emulsion for oxygenating the myocardium during the transluminal coronary angioplasty procedure, is a landmark in the field of injectable oxygen carriers, the so-called blood substitutes. This review discusses the advances made since this first emulsion was initially developed about 12 years ago. Attention is focused on the progress achieved in the preparation and selection of new, better-defined and faster-excreted fluorocarbons, and better surfactants, improved emulsions, knowledge of structure/property relationships along with an improved understanding of the physiologic response to their administration. These advances have led to the development of a second generation of highly concentrated, fluid and stable injectable oxygen carriers suitable for a broad range of clinical applications. Prospects for further progress and future generations of emulsions are also outlined.
Article
Nonspecific interactions between blotted proteins and unrelated secondary antibodies generate false positives in immunoblotting techniques. Some procedures have been developed to reduce this adsorption but they may work in specific applications and be ineffective in other ones. "Double-blotting" has been developed to overcome this problem. It consists of interpolating a second blotting step between the usual probings of the blot membrane with the primary antibody and the secondary antibodies. This step, by isolating the primary antibody from the interfering proteins, guarantees the specificity of the probing with the secondary antibody. This method has been developed for the study of erythropoietin in concentrated urine since a strong nonspecific binding of biotinylated secondary antibodies to some urinary proteins is observed using classical immunoblotting protocols. However, its concept makes it usable in other applications that come up against this kind of problem. This method is expected to be especially useful for investigating proteins that are present in minute amounts in complex biological media.
Article
To study central circulation at different levels of hemoglobin (Hb) concentration, five subjects performed submaximal and maximal exercise in three different situations: 1) control, 2) after venesection of 800 ml of whole blood, and 3) after reinfusion of the red blood cells about 30-35 days after venesection. Maximal oxygen uptake (VO2 max) decreased from 4.27 l-min-1) at control to 4.03 l-min-1 after venesection (P less than 0.05) and increased to 4.61 l-min-1 after reinfusion (P less than 0.05). Maximal values on cardiac output (Q), heart rate (HR), and stroke volume (SV) were the same in the three situations. Thus, there was no compensatory increase in Qmax due to the lowered arterial oxygen content (Cao2) after venesection. An increase of the Cao2 (Hb concentration) and a lowering of the Cvo2 contributed equally to the increased VO2 max after reinfusion. At a given submaximal VO2, HR and blood lactates were increased at lowered Hb concentration and decreased at increased Hb concentration over control levels. Correlation coefficient for the change in Q in relation to the acute change in Hb concentration at a given submaximal VO2 was -0.49 (P less than 0.05).
Article
Reaction of hemoglobin solutions with members of a class of diimidate esters leads to the formation of cross-linked intermolecular or intramolecular complexes depending on the relative concentration of hemoglobin and the length of the carbon chain of the imidate esters. The products have a life-span in the circulation of rabbits significantly greater than that of unmodified hemoglobin and it is suggested that they may serve as plasma protein extenders.
An unsaturated lipid made from 2,4-octadecadienoic acid was used as a component of phospholipid vesicles. The vesicles (0.2 micron phi) was prepared by an extrusion method, and the unsaturated lipid was polymerized with gamma-ray. Vesicles constructed from the polylipid show enormous stability during long term storage in frozen state and can be handled easily. Negative effect could not be confirmed in vitro tests. This system satisfies all the physiological conditions, such as oxygen transport ability and solution properties as a blood substitute.
Article
Two new potent allosteric effectors of hemoglobin, RSR-4 [2-[4-[[(3,5-dichloroanilino)carbonyl]-methyl]phenoxy]-2- methylpropionic acid] and RSR-13 [2-[4-[[(3,5-dimethlanilino)carbonyl]methyl]-phenoxy]-2-methylp rop ionic, are compared to the previously reported compounds L3,5 and L3,4,5 [Lalezari, I., Lalezari, P., Poyart, C., Marden, M., Kister, J., Bohn, B., Fermi, G., & Perutz, M. F. (1990) Biochemistry 29, 1515]. Unlike L3,5 and L3,4,5, RSR-4 and RSR-13 are less impeded by physiological concentrations of serum albumin. RSR-4 has also been shown to be more effective than L3,5 in shifting the allosteric equilibrium of bovine Hb toward the low-affinity T-state. X-ray crystal studies show that both RSR-4 and RSR-13 bind to only one pair of symmetry-related sites in the Hb central water cavity whereas previous studies on L3,5 and L3,4,5 demonstrated a second pair of symmetry-related binding sites near Arg 104 beta. Three major interactions between these allosteric effectors and Hb include the acid group with the guanidinium group of C-terminal Arg 141 alpha, the effector's amide oxygen with the ammonium ion of Lys 99 alpha, and the phi electrons of the halogenated or methylated aromatic ring and Asn 108 beta. No explanation has been found for the difference in number of binding sites observed for RSR-4 and RSR-13 (two sites) compared to L3,5 and L3,4,5 (four sites); also no correlation has been made between the number of binding sites and degree of allosteric shift in the oxygen equilibrium curve.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Hypoxia causes an increased production of erythropoietin (EPO), but the time course of the EPO response in humans has not been well characterized. This study examines the relationship between the duration of normobaric hypoxic exposure and plasma EPO levels in healthy human subjects. Six volunteers breathed a gas mixture of 10.5% O2-89.5% N2 continuously for 5, 60, and 120 or intermittently for 240 min. O2 saturations were maintained between 75 and 85% during the exposure. Arterial pH was 7.467 +/- 0.019, PO2 37.05 +/- 2.43 Torr, and PCO2 36.69 +/- 2.05 Torr. O2 half-saturation pressures of hemoglobin were normal for all subjects. Plasma EPO was measured every 30 min for 360 min by radioimmunoassay. No increase in EPO was seen after the 5- and 60-min exposures. However, a 50% increase was seen 240 min after the initiation of the 120-min hypoxic exposure (P less than 0.01). Intermittent exposure resulted in an increase of EPO by 52% 360 min after the onset of exposure (P less than 0.05). Therefore, exposing humans continuously to an inspiratory O2 fraction of 0.105 for 120 min or intermittently for 240 min provides a sufficient stimulus to increase production of EPO.
Article
Physical training at high altitude improves performance at high altitude. However, studies assessing performance improvements at sea level after training at higher altitudes have produced ambiguous and inconclusive results. Hypoxia-induced secondary polycythemia is a major contributor to increased work capacity at altitude. The common finding upon exposure to hypoxia is a transient increase in haemoglobin concentration and haematocrit because of a rapid decrease in plasma volume followed by an increase in erythropoiesis per se. Both nonathletes and elite endurance athletes have maximal reticulocytosis after about 8 to 10 days at moderate altitude. Training periods of 3 weeks at moderate altitudes result in individual increase of haemoglobin concentration of about 1 to 4%. A more accentuated increase in haemoglobin can be obtained with longer sojourns at moderate altitude. The normal erythropoietin reaction upon exposure to hypoxia comprises initially increased levels followed by a decrease after about 1 week. Thus, the maintenance of a high erythropoietin concentration is not a prerequisite for a sustained increase in erythrocyte formation at high altitude. The main pharmacological modulator of erythropoietin production seems to be adenosine. But modulators such as growth hormone and catecholamines may also potentiate the effect of hypoxia per se on erythropoietin production. On the other hand, there is a risk that the stress hormones may induce a relative depression of the bone marrow particularly in the early phase of altitude training when the adaptation is minimal and the stress reaction is most accentuated. The most important 'erythropoiesis-specific' nutrition factor is iron availability which can modulate erythropoiesis over a wide range in humans. Adequate iron stores are a necessity for haematological adaptation to hypoxia. However, at moderate altitude, there is a need for rapid mobilisation of iron and even if the stores are normal there is a risk that they cannot be mobilised fast enough for an optimal synthesis of haemoglobin. Data from healthy athletes training at moderate altitudes suggest a true increase in haemoglobin concentration of about 1% per week. Complete haematological adaptation occurred when sea level residents have similar haemoglobin concentrations at moderate altitude compared with residents. The normal difference in haemoglobin concentrations can be estimated to be about 12% between permanent residents at sea level and at 2500m above sea level. This difference indicates a necessary adaptation time of about 12 weeks. If the training period at moderate altitude must be shorter, several sojourns at short intervals are recommended. The important factor in haematological adaptation in athletes at moderate altitude is hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)
Article
Altitude training may improve performance by a number of mechanisms. Acclimatization may improve both oxygen delivery and extraction. Hypoxic exercise may increase the training stimulus thus magnifying the effects of endurance training. Conversely, high altitude decreases VO2max and reduces the workloads at which training occurs. At altitude, base training is performed at a slower velocity and lower oxygen uptake (lower absolute workload) compared to sea level, though heart rate is similar and lactate is higher (probably greater relative workload). Interval workouts are performed at a lower absolute workload at altitude and are associated with lower peak heart rates and blood lactate concentrations. Red cell volume is increased during altitude training, as long as iron stores are normal. We suggest that for performance at altitude, acclimatization and/or hypoxic exercise is preferable; for performance at sea level, living at altitude (acclimatization) with sea level training may be the optimal strategy. However neither approach is a substitute for a carefully designed training program including appropriate rest and nutrition.
Article
There can be little doubt that training at altitude is fundamental to preparing an athlete for competition at altitude. However the value of training at altitude for competition at sea level appears on the one hand to lack total acceptance amongst sports scientists; and on the other to hold some cloak of mystery for coaches who have yet to enjoy first hand experience. The fact is that very few endurance athletes will ignore the critical edge which altitude training affords. Each fraction of a percentage of performance advantage gained through methods which are within the rules of fair play in sport, may shift the balance between failure and achievement. Moreover, there is growing support for application of training at altitude for speed-related disciplines. This paper aims to demystify the subject by dealing with practical aspects of training at altitude. Such aspects include a checklist of what should and should not be done at altitude, when to use altitude relative to target competitions, and specific training examples.
Article
The symmetrical trifunctional cross-linking reagent trimesoyl tris(methyl phosphate) (3), reacts selectively with amino groups (beta 1Val and beta 82Lys) in the diphosphoglycerate binding site of human hemoglobin A, producing cross-linked tetrameric species in good yield. A major species is triply linked, alpha alpha beta 1(82) greater than B beta 82, where B symbolizes benzene-1,3,5-tricarbonyl. Both this triply linked species and the doubly linked species, alpha alpha beta 1B beta 82, produced from deoxyhemoglobin have a considerably lower oxygen affinity than does native hemoglobin while maintaining a high degree of cooperativity (n50 = 2.4), making them potentially useful as red cell substitutes, in principle delivering twice as much oxygen as whole blood between pO2 = 100 and = 40 Torr. The yield of products indicates that triply and doubly linked species form in parallel so that there are independent routes to each. It is proposed that differences in routes are due to stereoisomerism about the amide bonds which form from reaction of the reagent with the protein.
Article
This study evaluated the newly developed artificial red blood cells named Neo Red Cells (NRC) after hemorrhagic shock in mongrel dogs. NRC is prepared as microcapsules by a method in which stroma-free hemoglobin is encapsulated using a bimolecular lipid membrane called liposome. The particle size is 0.2 μm, methemoglobin content is less than 5% and the hemoglobin concentration is 5.6 g/dl. We analyzed blood gases and hemodynamics and carried out laboratory examinations after 59-88% blood exchange using NRC. The hemodynamic parameters returned to the normal range after NRC. Inhaling normal room air, oxygen carried by NRC was 60.40% at the exchange rate of 88%. Renal and hepatic function and other laboratory findings were normal after administration of NRC. After further study and improvement NRC could be considered suitable as artificial blood for treatment of hemorrhagic shock.
Article
The approval of Fluosol, a fluorocarbon emulsion for oxygenating the myocardium during the transluminal coronary angioplasty procedure, is a landmark in the field of injectable oxygen carriers, the so-called blood substitutes. This review discusses the advances made since this first emulsion was initially developed about 12 years ago. Attention is focused on the progress achieved in the preparation and selection of new, better-defined and faster-excreted fluorocarbons, and better surfactants, improved emulsions, knowledge of structure/property relationships along with an improved understanding of the physiologic response to their administration. These advances have led to the development of a second generation of highly concentrated, fluid and stable injectable oxygen carriers suitable for a broad range of clinical applications. Prospects for further progress and future generations of emulsions are also outlined.
Article
The physical performance of 12 anemic patients on renal dialysis was investigated following treatment of renal anemia with recombinant human erythropoietin (rhEPO; 40-120 U/kg, 3 times a week). Exercise intensity at a heart rate of 130 beats/min (PWC130) on a bicycle ergometer was assessed before rhEPO treatment, after reaching the target hematocrit (73 +/- 18 days), and in the maintenance phase (211 +/- 53 days). Hemoglobin concentrations measured at these time points were 7.3 +/- 1.2, 11.9 +/- 1.5, and 12.1 +/- 1.4 g/dl, respectively. PWC130 rose from 77 +/- 27 to 104 +/- 37 and 104 +/- 51 W, respectively. Aerobic threshold (i.e. blood lactic acid concentration of 2 mmol/l) shifted to higher workloads indicating improved muscle oxygen supply.
Article
Correction of the anemia that is common among chronic hemodialysis patients by treatment with human recombinant erythropoietin (rHuEPO), even if incomplete, improves physical performance of patients. Oxygen uptake and physical work capacity at maximal work loads and at the anaerobic threshold increase by approximately 20%. Analysis of underlying mechanisms by pulmonary function tests and ergospirometry demonstrate that improved oxygen transport in the blood and its concomitant changes of the anaerobic threshold and heart rate appear to be main causes of improvement. Parameters of respiratory mechanics and gas exchange remain essentially unaltered.
Article
We describe the actions of two new allosteric effectors of hemoglobin, 2-[4-(3,5-dichlorophenylureido)phenoxy]-2-methylpropionic acid (L35) and 2-[4-(3,4,5-trichlorophenylureido)phenoxy]-2-methylpropionic acid (L345). Each of them binds to two pairs of symmetry-related sites in the central cavity of human deoxyhemoglobin. One pair of sites overlaps with that occupied by bezafibrate [Perutz et al. (1986) J. Am. Chem. Soc. 108, 1064-1078]. The other sites are new, and the pair occupied by L35 is different from that occupied by L345. All the sites are at least 20 A from the site where organic phosphates are bound. L345 is by far the most potent allosteric effector of hemoglobin ever described. At a concentration of 0.1 mM, it raises the P50 of a suspension of red cells by 50%; at 0.2 mM it raises the P50 2.5-fold. At acid pH, it reduces Hill's coefficient to near unity and prevents complete oxygen saturation even under 1 atm of pure oxygen. In azidemethemoglobin at pH 6, it induces a transition to higher spin. These properties are reminiscent of those of teleost fish hemoglobins that exhibit a Root effect. The influence of L35 and L345 and that of organic phosphates on the oxygen affinity are additive, but they compete with chloride. L35 acts more weakly than L345, but can be made to induce the same effects as L345 alone by adding inositol hexaphosphate. Both compounds increase the alkaline and acid Bohr effects. They alter the bimolecular kinetics of CO recombination after a flash by increasing the slowly reacting fraction of hemoglobin in the T state at the expense of the fast-reacting fraction in the R state.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
To improve the outcome of trauma victims and of patients undergoing high-blood-loss surgical procedures and to avoid the many serious complications of blood transfusion, there is a need for an oxygen-carrying blood substitute. Synthetic erythrocytes composed of liposome-encapsulated hemoglobin (LEH) represent one of the significant research efforts in this direction. The purpose of the present study was to examine some of the cardiovascular, hematologic, and biochemical effects of a recently developed LEH preparation in the conscious rat (n = 7). LEH increased mean arterial pressure (MAP) by +18.7 +/- 4.7 mm Hg (P less than 0.01) and heart rate (HR) by +117 +/- 18 beats/min (P less than 0.05). Platelet count dropped to 40% of basal value (P less than 0.01), while plasma thromboxane B2 (TXB2) increased by +25.1 +/- 5.4 pg/100 microliters (P less than 0.001). There was no effect on plasma 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). Hemoglobin and hematocrit levels were elevated as well as the white blood cell count [( WBC] lymphocytosis). The platelet and TXB2 responses to LEH showed negative correlation (R = -0.56, P less than 0.01). The injection of the liposome vehicle (LIP) decreased MAP by -16.5 +/- 5.1 mm Hg (P less than 0.01) and platelets, but increased HR, WBC, and TXB2. All observed effects exerted by LEH and LIP were transient, and basal levels obtained 120 min after LEH injection. These data suggest that while LEH maintains some physicochemical properties of red blood cells, its biological properties at the present time indicate potential cardiovascular and hematological liabilities. Furthermore, it seems that the phospholipid bilayer alone or in combination with free Hb might be responsible for the biological effects of LEH.
Article
Recombinant human erythropoietin is a major advance in the management of patients with chronic renal failure. The sustained dose-dependent rise in haematocrit which it produces effectively abolishes symptoms of anaemia, but at the cost of an increase in blood viscosity. This in turn predisposes to increased vascular resistance and the development of hypertension. Over half of all deaths of patients with end-stage renal failure are from cardiovascular disease, notably myocardial infarction, heart failure, and stroke, for which hypertension is a known risk factor. Erythropoietin-related increases in blood pressure are therefore of particular concern, and seem to be most severe in previously hypertensive patients. There is now a need to establish the optimum rate and extent of rise of haematocrit required to alleviate symptoms without incurring undue risk.
Article
Synthetic Erythrocytes (SE) are an example of the application of liposome technology to a medical product, large quantities of which are infused into a human patient.
Article
Liposome-encapsulated hemoglobin (LEH) is being developed at the Naval Research Laboratory as a universally transfusable oxygen-carrying blood replacement. A chemical engineering scale-up feasibility study has been completed recently. We report here the development of an encapsulation method which produces liters of phospholipid/cholesterol liposomes containing at least 16 g% hemoglobin in a few hours. The 0.2 micron liposomes are produced with a Microfluidizer TM (Microfluidics Corp., Newton, MA) adapted for this purpose, and then washed and sterile filtered using a Pellicon (Millipore, Bedford, MA) tangential flow filtration device. Previously, production limitations and lack of sterility have been serious barriers to toxicity testing for all the researchers engaged in related investigations. The biophysical properties of the LEH thus produced are ideal for use as a blood substitute, resembling those of red blood cells. The oxygen-binding affinity of LEH can be maintained at the level of fresh whole blood for many weeks by co-encapsulation of pyridoxal-5-phosphate. The circulation persistence time of liposomes is a function of the type of phospholipid. We have developed a formulation which has a circulation persistence time of 15-20 hours. The LEH oxygen binding characteristics, circulation half-life and its lipid composition dependence, scale-up preparation method, and a sterilization method are presented.
Article
Increased performance after blood transfusion was first demonstrated 40 years ago, but the technique did not create attention until the early 1970s when it was dubbed 'blood doping' by the media. The procedure can increase both maximal oxygen uptake (VO2max) and performance in endurance sports. It was forbidden by the International Olympic Committee (IOC) after the 1984 Olympics, despite the fact that no methods had been devised for unequivocal detection. There are 2 types of blood transfusions: either from a matching donor (heterologous transfusion) or reinfusion of the subject's own blood (autologous transfusion). While the subject's haemoglobin normalise, blood can be stored in commercially available blood bags for 4 to 5 weeks in a 'blood bank' (+4 degrees C), or as frozen erythrocytes with a storage time up to several years. A blood doping procedure, independent of transfusion type, induces some pronounced physiological changes. A desired effect of blood doping is the increased total red blood cell mass leading to increments in haemoglobin, which after successfully induced blood doping is in the magnitude of at least 10%. In addition, storing of blood leads to a constant decline in RBC count due to the limited life span of the RBC (haemolysis). Thereby, serum iron and bilirubin levels will increase and reach maximal levels within the first day. Haemolysis is more accentuated after storing of blood in a blood bank than in the frozen state. The regulation of RBC formation is mediated through a negative feed-back mechanism via the glucoprotein hormone erythropoietin.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
2-[4-(3,4-Dichlorophenylureido)phenoxy]-2-methylpropionic acid, LR16, combines with two symmetrically related sites in the central cavity of deoxyhemoglobin, 20 A away from the binding site of 2,3-bisphosphoglycerate, and acts as an allosteric effector synergistic with 2,3-bisphosphoglycerate. LR16 (1 mM) raises P50, the partial pressure of oxygen needed to achieve half-saturation with oxygen of a hemolysate of human hemoglobin, about 50 times more strongly than 1 mM 2,3-bisphosphoglycerate. Oral administration of LR16 (at small doses that produced no ill effects) to rats that were fed a diet rich in cholesterol caused substantial reductions of total serum cholesterol and low density lipoprotein-cholesterol, while high density lipoprotein-cholesterol remained unchanged.
Article
The purpose of this study was to investigate the effect of infusion of 400 mL of red blood cells (RBCs) on 10-km track race time, submaximal heart rate, hematocrit, 2,3-diphosphoglycerate, and partial pressure of oxygen at 50% hemoglobin saturation. Six highly trained, male, distance runners twice donated a unit of RBCs, which was frozen for subsequent reinfusion. Eleven weeks after the second donation, they undertook a series of three competitive 10-km races on a standard 400-m track: before infusion, after 100 mL of saline solution, and after 400 mL of autologous, previously frozen deglycerolized RBCs. All subjects took all trials in this double-blind, placebo, crossover, experimental design. Running time was recorded at each 400-m split, and blood was collected prior to each trial. The data were analyzed by analysis of variance. Results following the RBC infusion showed a significantly higher hematocrit concentration, a significantly faster 10-km run, a nonsignificant decrease in submaximal heart rate (10 beats faster 10-km run, a nonsignificant decrease in submaximal heart rate (10 beats per minute), and no significant changes in either 2,3-diphosphoglycerate or partial pressure of oxygen at 50% hemoglobin saturation. Erythrocythemia induced by the infusion of 400 mL of autologous packed RBCs effectively increased performance capacity in a 10-km track race, probably due to an increase in oxygen delivery to the working muscles.
Article
Transfusion of autologous blood (blood doping) has been used by athletes to improve performance in sports events. This practice has been banned by the International Ski Federation (FIS) and the International Olympic Committee (IOC). So far, no reliable method for detection of blood doping has been available. In the present study, a group of six elite cross-country skiers, who were phlebotomized and retransfused with 1350 ml of blood 4 weeks later, was compared with a control group (n = 7) in whom no blood doping was performed. The blood was stored at +4 degrees C for 4 weeks. Hemoglobin increased by 7.9% from the prephlebotomy level and by 14% from the preinfusion level. The reinfusion of blood caused a 60% reduction (P less than 0.001) in serum erythropoietin in 24 h and a sharp increase (P less than 0.05) in serum iron and bilirubin after a test race performed on the day of reinfusion. It is therefore concluded that a combination of measurements of hemoglobin and bilirubin, iron, and erythropoietin in serum could detect 50% of the blood-doped athletes by a single test sample during the 1st week after reinfusion. If two test samples were used, an increase in Hb of more than 5%, and a decrease in serum erythropoietin by more than 50%, would be discussed in 50% of the blood-doped athletes throughout the first 2 weeks after reinfusion and without implicating any of the controls.
Article
Since perfluorochemicals are characterized by a high solubility for gases, emulsions of per fluorinated compounds have been proposed as artificial blood substitutes (Clark and Gollan, 1966; Naito and Yokoyama, 1978; Beisbarth and Suyama, 1982; Geyer, 1982, 1983). Among the different perfluorochemicals investigated, Fluosol-DA 20% (FDA20) has been used successfully as an O2 transport medium and plasma expander for different experimental animals and for humans. Our knowledge of respiratory gas transport of FDA20 and blood-FDA20 mixtures is, however, mainly based on theoretical investigations and calculations, which have been derived from separate data for blood and FDA20, and presumes that the fluorocarbon emulsion does not affect the O2-affinity of hemoglobin or the acid-base status of blood. In addition, calculations and measurements of the O2 solubility in the two Fluosol emulsions (FDA20 and FDA35) have resulted in disagreement (Naito and Yokoyama, 1978; Zander and Makowski, 1982).
Article
Recently, the U.S. Olympic Committee revealed that 7 members of its 24-member Olympic cycling team, including 4 medalists, had received blood transfusions in an effort to enhance their performance in the Los Angeles Olympic games. Ironically, public disclosure took place during National Blood Donor Month and at a time when blood shortages were being reported in southern California and elsewhere in the country. According to team officials, the athletes were given transfusions of whole blood, collected from both relatives and from unrelated donors, in a motel room. Details of the collection, storage, and compatibility and safety testing have not been released. Blood is a drug. Collection, storage, and compatibility testing of blood for transfusion are carefully prescribed by the Food and Drug Administration. Facilities for blood collection and transfusion are registered, licensed, and inspected for compliance. Like other drugs, blood should be given only for medical indications. In 1976 the Medical Commission of the International Olympic Committee formally condemned the practice of blood transfusion for athletes in good health. As of this writing, however, neither the International Olympic Committee nor the U.S. Olympic Committee has explicitly forbidden blood doping. They should.
Article
Nephrectomized rats exposed to intense hypoxia produce sufficient erythropoietin (Ep) to detectably increase their plasma Ep titers. Extrarenal Ep production is no longer detectable if nephrectomized rats are also subjected to 80% hepatectomy prior to being made hypoxic at 0.465 atmos and is barely detectable but significantly lower than in nephrectomized rats when exposed to 0.435 atmos. These results suggest that the liver plays an important role in the production of extrarenal erythropoietin.
Article
The extent of dissociation of various hemoglobins into subunits was estimated from their elution volumes (V(e)) on G-100 Sephadex. Under the same controlled conditions carboxyhemoglobins A, A3 (A(1)), F, S, and C all had the same elution volumes. The carboxy and cyanmet derivatives of hemoglobin Kansas (a variant with very low oxygen affinity) had a relatively high V(e), indicating a decreased mean molecular weight and therefore an increased tendency to form dimers and even monomers. Conversely, the liganded derivatives of hemoglobin Chesapeake (a variant with high oxygen affinity) had a relatively low V(e), suggestive of an impaired degree of subunit dissociation. Deoxyhemoglobin Chesapeake had a V(e) identical with that of deoxyhemoglobin A. Cat hemoglobin, known to have an unusually low oxygen affinity, was found to have a higher V(e) than human, dog, rabbit, rat, or guinea pig hemoglobins. Haptoglobin is thought to bind alphabeta dimers in preference to the alpha(2)beta(2)-tetramer. The comparative haptoglobin affinities of the human hemoglobins were measured by competition between the test hemoglobin and radioactive reference hemoglobin for haptoglobin binding sites. Hemoglobins A, F, S, and C all seemed to bind equally readily, but hemoglobin Kansas and cat hemoglobin showed a higher affinity, and hemoglobin Chesapeake a lower affinity. These results are in accord with recently proposed models which predict that hemoglobins which have an increased degree of subunit dissociation will have a low oxygen affinity, and vice versa.
Article
2,3-Diphosphoglycerate is present in the red cells of many species at about equimolar concentration to haemoglobin. It lowers the oxygen affinity and thus facilitates oxygen unloading because it is preferentially bound to deoxyhaemoglobin in the ratio of one mole per tetramer.
Article
The relative importance of blood volume (BV) for the maximum aerobic power (VO2 max) was evaluated in healthy subjects by sequential measurements without intervention under two conditions: 1) after hemodilution with a plasma expander, thus increasing BV but keeping red cell mass constant and lowering hemoglobin concentration [Hb], and 2) after whole blood withdrawal, which restored BV to control conditions but reduced red cell mass and [Hb] to equal conditions under 1. After BV expansion (avg 700 ml), we found an unchanged VO2 max compared with control data despite lowered [Hb]. Cardiac output (Q) was increased after BV expansion at rest and during all exercise levels (maximum 27.4 and 29.5 l . min-1, respectively). Peak stroke volume was increased from 144 to 173 ml. Arterial blood pressures were either unchanged or lowered. In contrast, after blood letting to a similar [Hb], we found a significantly reduced VO2 max. These findings indicate a significant influence of the size of the blood volume on cardiac performance. The increased Qmax is discussed in relation to preload, inotropic state, heart rate, and afterload. Plasma volume expansion causes increased preload which may explain this primary effect on the central circulation (Frank-Starling effect).
Article
The intent of blood doping is to increase maximal aerobic power by increasing the capacity of blood to carry oxygen. This manipulation gained notoriety in the sports world because of rumors of blood doping by competitors in endurance events. Researchers also have become interested in induced erythrocythemia because its study provides insight into the limiting factor(s) of maximal aerobic power (Vo2max). It is concluded in this review that to increase Vo2max, it is necessary to elevate significantly the hemoglobin concentration by infusing at least 900 ml of blood. The use of inadequate reinfusion volumes, premature reinfusion of the blood following withdrawal, and storage of the blood by refrigeration rather than by freezing are major reasons for the contradictory findings from earlier studies of blood doping. Changes in blood volume and 2,3-diphosphoglycerate following blood doping are transient and, other than during the first 24 h post infusion, appear to be inconsequential. In addition, this review also examines related issues such as attendant hemodynamic and lactate changes, the need of controls, and ethical considerations in blood doping.
Article
Erythropoietin (EPO) is the primary hormone responsible for the growth and maturation of red blood cells in mammals. In contrast to many other growth factors, the specificity of EPO for mature erythroid cells has lead to its development as a safe and efficacious therapeutic, EPREX. The medical benefits of EPREX have been well established in the treatment of anaemic chronic renal failure patients, anaemic HIV patients treated with AZT, cancer chemotherapy patients, and patients wishing to donate their own blood prior to elective surgery (autologous predonation). Due to the chronic nature of EPO therapy, it would be desirable to have an orally administered 'second generation' molecule. An understanding of the structural basis of the interaction of EPO with its receptor will aid in the design of an oral anaemia drug. In this study, a series of mutations have been generated in a truncated form of the receptor comprising the extracellular region, termed EPO binding protein (EBP). One mutant, in which alanine replaces phenylalanine at position 93 (F93A) has a 500-fold reduction in binding compared to wild-type EBP. A neutralizing anti-EBP antibody binds poorly to the F93A mutant, while a non-neutralizing anti-EBP antibody binds wild-type and F93A equally well. Information from this mutational analysis can be applied to a receptor 3-D model and ultimately used in drug development.
Article
We encapsulated erythropoietin (Epo) in dipalmitoylphosphatidylcholine (DPPC) liposomes with soybean-derived sterols (SS-liposomes) and its glucoside (SG-liposomes) by reverse-phase evaporation vesicle method, and evaluated them by subcutaneous administration in rats. With 4 min of sonication, the damage to Epo activity was observed mainly in the non-encapsulated Epo in the liposomes. This study indicated that the bilayer of liposomes had the ability to protect the Epo activity, by reducing the aggregation that was caused by interaction between Epo molecules. The SG-liposomes had a higher retention of the Epo activity the SS-liposomes. 25.3% or 33.6% of activity was retained by SS-liposomes under the conditions of 4 min or 1 min of sonication, while 53.3% or 58.3% of the activity was retained by SG-liposomes under the same conditions. Shorter sonication was available to minimize the loss of the Epo activity. Epo in SG-liposomes appeared to increase the activity.
Article
This report employs a statistical genetic approach to analyze quantitative oxygen transport variables in a high-altitude (4,850-5,450 m) native Tibetan population and demonstrates the presence of a major gene influencing % O2 saturation of arterial hemoglobin. This result suggests the hypothesis that individuals with the dominant allele for higher % O2 saturation have a selective advantage at high altitude. Studies of the biologically distinctive Himalayan and Andean populations have greatly influenced thinking about ongoing human evolution and adaptation; this is the first statistical evidence for a major gene enhancing oxygen transport in a high-altitude native population.
Article
In an attempt to enhance the therapeutic efficacy of interleukin-2 (IL-2), recombinant human IL-2 was encapsulated either in large conventional liposomes or in small (mean diameter 65 nm), unilamellar, long-circulating, extravasating liposomes [referred to as sterically stabilized liposomes (SSLs)]. The SSL-IL-2 activity was assessed in vitro and in mice in comparison with soluble IL-2, IL-2 in conventional liposomes (non-SSL-IL-2), and pegilated IL-2 (PEG-IL-2). The main observations were as follows: (a) SSLs were far better carriers than conventional liposomes with regard to encapsulation efficiency and pharmacokinetics; (b) > 85% of IL-2 biological activity was consistently encapsulated in SSLs; (c) SSL-IL-2 was much more stable than soluble IL-2 at 4 and 37 degrees C; (d) SSL-IL-2, but not "empty" liposomes, bound in vitro to IL-2 receptor-bearing T-cells, indicating that the domain of the cytokine molecule involved in binding to the receptor is exposed on the outer liposome membrane; (e) release of IL-2 from the liposomes was not required for its in vitro biological activity; (f) plasma half-lives (t1/2 alpha, t1/2 beta) and area under the curve (AUC) of SSL-IL-2 were 10-30 times greater than those of soluble IL-2 and similar to those of PEG-IL-2; and (g) IL-2 is released from the SSLs in vivo with a t1/2 of approximately 40 min, although the SSL-IL-2s retained their steric stabilization in the plasma for > 4 h, with little liposome accumulation in the reticuloendothelial system. These data, together with the improved immunomodulatory and antitumor activity of SSL-IL-2 in mice, suggest that SSL-IL-2 might be a therapeutic agent superior to soluble IL-2.