Dose-Response Relationship between Red Blood Cell Distribution Width and In-Hospital Mortality in Oldest Old Patients with Acute Ischemic Stroke

<b><i>Introduction:</i></b> It is crucial to identify predictors of mortality in the early stage of acute ischemic stroke for the oldest old (aged ≥80 years) because of their poor overall survival outcomes. However, limited data are available as the oldest old have often been excluded from previous clinical studies. Hence, we aimed to assess the predictive effect of red blood cell distribution width on in-hospital mortality and the dose-response relationship between the red blood cell distribution width and in-hospital mortality in oldest old with acute ischemic stroke. <b><i>Methods:</i></b> A retrospective cohort study was performed in two tertiary hospitals. Patients aged ≥80 years admitted due to acute ischemic stroke from January 1, 2014, to January 31, 2020, were included in the study. We divided the eligible patients into 3 groups with tertiles of red blood cell distribution width. Restrictive cubic spline and robust locally weighted regression analysis were performed to test the dose-response relationship between red blood cell distribution width and the in-hospital mortality risk. All-cause in-hospital mortality was the main study outcome. <b><i>Results:</i></b> Overall, 606 patients were included in the final analysis. Red blood cell distribution width was categorized into 3 groups (T1: &#x3c;13.7%, T2: 13.8–15.7%, and T3: &#x3e;15.7%). The rationality of this categorization was then validated with restricted cubic spline and robust locally regression smoothing scatterplot, respectively. After adjusting for demographic and clinical features, a higher red blood cell distribution width was independently associated with in-hospital mortality and the hazard ratio (HR) was 3.31 (95% CI 2.47–4.45, <i>p</i> &#x3c; 0.001). There was a positive dose-response relationship between red blood cell distribution width and mortality risk. Sensitivity analysis identified no conspicuous change in the HR. <b><i>Conclusions:</i></b> Red blood cell distribution width may be a valuable and simple measure for predicting in-hospital mortality in oldest old patients with acute ischemic stroke.

In vivo volume and hemoglobin dynamics of human red blood cells

Human red blood cells (RBCs) lose ∼30% of their volume and ∼20% of their hemoglobin (Hb) content during their ∼100-day lifespan in the bloodstream. These observations are well-documented, but the mechanisms for these volume and hemoglobin loss events are not clear. RBCs shed hemoglobin-containing vesicles during their life in the circulation, and this process is thought to dominate the changes in the RBC physical characteristics occurring during maturation. We combine theory with single-cell measurements to investigate the impact of vesiculation on the reduction in volume, Hb mass, and membrane. We show that vesicle shedding alone is sufficient to explain membrane losses but not volume or Hb losses. We use dry mass measurements of human RBCs to validate the models and to propose that additional unknown mechanisms control volume and Hb reduction and are responsible for ∼90% of the observed reduction. RBC population characteristics are used in the clinic to monitor and diagnose a wide range of conditions including malnutrition, inflammation, and cancer. Quantitative characterization of cellular maturation processes may help in the early detection of clinical conditions where maturation patterns are altered.

RBC volume deficiency in patients with excessive orthostatic decrease in cerebral blood flow velocity

BACKGROUND

Orthostatic intolerance (OI) is common but heterogeneous. There is a subgroup of OI patients who have excessive decrease in cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries (MCAs) during head-up tilt without systemic blood pressure change. This study evaluated the role of blood volume reduction in such patients.

METHODS

Patients with idiopathic OI who had excessive orthostatic decrease (>20% of the supine level) in mean CBFV of bilateral MCAs and who also received blood volume determination were collected. The chromium (⁵¹Cr) dilution method was used for red blood cell (RBC) volume determination in these patients. The blood volume was expressed as a percentage of the expected volume. These patients were further divided into two groups, those with postural tachycardia syndrome (POTS group) and those without (non-POTS group). The data of RBC volume were compared between the two groups. Besides, we used multivariate linear regression to evaluate the factors that predict RBC volume.

RESULTS

Twenty-five patients (13 females, median age = 28 years) were enrolled in this study. Nine of these patients had POTS (5 females, median age = 26 years) and 16 did not (8 females, median age = 29.5 years). Compared with the expected volume, the RBC volume was significantly reduced in all patients (median = 82% of the expected volume). Moreover, the RBC volume was significantly lower in the POTS group than that in the non-POTS group (78% vs. 85% of the expected volume, p = 0.013). The orthostatic decrease of MCA flow velocity was 28.3% in the POTS group and 32.5% in the non-POTS group (p = 0.140). The orthostatic pulsatility index increment was 15.4% in the POTS group and 20.5% in the non-POTS group (p = 0.438). Moreover, basic demography and hemoglobin levels were not different between the two groups. After multivariate linear regression (dependent variables including age, sex, body surface, and groups), only the presence of POTS significantly predicted the RBC volume (p = 0.006).

CONCLUSION

The results of our study indicated that low RBC volume may play an important role in the pathophysiology of OI in this group of patients. Moreover, its role seems even more relevant in patients with POTS than in those without. Further studies for mechanistic evaluation are needed in the future.

Pathophysiology of red cell volume

In the current work, we review three situations where red cell volume changes are important. Red cell apoptosis (eryptosis) accounts for the removal of ageing and damaged erythrocytes from the circulation by macrophages. Amongst other cellular responses, eryptosis is associated with net cytosolic KCl loss and concomitant cell shrinkage. KCl efflux is mediated by activation of Ca(2+)-activated K(+) (Gardos) channels, permitting downhill movement of K(+) and electrically obliged Cl(-) through, as yet, incompletely described pathways. Red cells from patients suffering from sickle cell disease demonstrate progressive dehydration. Osmolyte loss is accounted for by the activation of two separate pathways. KCl cotransport, normally quiescent in red cells from HbA individuals, is activated under deoxygenated conditions and mediates net KCl efflux. Furthermore, intracellular Ca(2+) is elevated, probably as a result of Ca(2+) influx through a deoxygenation induced non-selective cation pathway termed P(sickle). This results in Gardos channel activation coupled indirectly with Cl(-) loss. Finally, a number of red cell stomatocytoses have been described where alterations to erythrocyte volume are the result of increased membrane cation permeability, in particular to Na(+) and K(+). The emerging significance of non-selective cation pathways is common to each of these conditions, and, although differences exist between their properties, particularly with regard to activation and ion selectivity, it is conceivable that they represent activation of closely related pathways. The recent finding that many hereditary stomatocytoses are caused by mutations to band 3 (AE-1) raises the possibility that modifications to this transporter could account for altered cation fluxes under different conditions.

Low dose exogenous erythropoietin elicits an ergogenic effect in Standardbred horses

REASONS FOR PERFORMING STUDY

Recombinant human erythropoietin (rhuEPO) causes an increase in red blood cell production and aerobic capacity in other species; however, data are lacking on effects in the horse.

HYPOTHESIS

This study tested the hypothesis that rhuEPO administration would alter red cell volume (RCV), aerobic capacity (VO2max) and indices of anaerobic power.

METHODS

Eight healthy, unfit mares accustomed to the laboratory and experimental protocols were randomly assigned to either a control (CON, n = 4; 3 ml saline 3 times/week for 3 weeks) or EPO group (EPO, n = 4, 50 iu/kg bwt rhuEPO/3 ml saline 3 times/week for 3 weeks). Exercise tests (GXT) were performed on a treadmill (6% incline), 1 week before and 1 week after treatment. The GXT started at 4 m/sec, with a 1 m/sec increase every 60 sec until the horse reached fatigue. Oxygen uptake was measured via an open flow indirect calorimeter. Blood samples were collected before, during (each step) and 2 and 15 min post GXT to measure packed cell volume (PCV), haemoglobin concentration (Hb), blood lactate concentration (LA) and plasma protein concentration (TP). Plasma volume (PV) was measured using Evans Blue dye. Blood volume (BV) and RCV were calculated using PCV from the 8 m/sec step of the GXT.

RESULTS

There were no alterations (P>0.05) in any parameters in CON horses. By week 3, EPO produced increases (P<0.05) in resting PCV (37 +/- 2 vs. 51 +/- 2) and Hb (37%). RCV (26%) and VO2max (19%) increased, but BV did not change (P>0.05) due to decreased PV (-11%, P<0.05). There was a significant increase in velocity at VO2max and LApeak for horses treated with rhuEPO and substantial decrease (P<0.05) in VO2 recovery time when the pretreatment GXT was compared to the post treatment GXT. No differences (P<0.05) were detected for TP, VLA4, run time or Vmax.

CONCLUSIONS

Low dose rhuEPO administration increases RCV and aerobic capacity without altering anaerobic power.

POTENTIAL RELEVANCE

This study demonstrates that rhuEPO enhances aerobic capacity and exercise performance, a question relevant to racing authorities.

Col4a1 mutation in mice causes defects in vascular function and low blood pressure associated with reduced red blood cell volume

Collagen type IV is the major structural component of the basement membrane and COL4A1 mutations cause adult small vessel disease, familial porencephaly and hereditary angiopathy with nephropathy aneurysm and cramps (HANAC) syndrome. Here, we show that animals with a Col4a1 missense mutation (Col4a1(+/Raw)) display focal detachment of the endothelium from the media and age-dependent defects in vascular function including a reduced response to nor-epinephrine. Age-dependent hypersensitivity to acetylcholine is abolished by inhibition of nitric oxide synthase (NOS) activity, indicating that Col4a1 mutations affect vasorelaxation mediated by endothelium-derived nitric oxide (NO). These defects are associated with a reduction in basal NOS activity and the development of heightened NO sensitivity of the smooth muscle. The vascular function defects are physiologically relevant as they maintain in part the hypotension in mutant animals, which is primarily associated with a reduced red blood cell volume due to a reduction in red blood cell number, rather than defects in kidney function. To understand the molecular mechanism underlying these vascular defects, we examined the deposition of collagen type IV in the basement membrane, and found it to be defective. Interestingly, this mutation also leads to activation of the unfolded protein response. In summary, our results indicate that mutations in COL4A1 result in a complex vascular phenotype encompassing defects in maintenance of vascular tone, endothelial cell function and blood pressure regulation.

Red cell distribution width and acute coronary syndromes

It is well known that red cell distribution width (RDW) levels are affected by various clinical manifestations such as iron deficiency, thrombocytopenia, and inflammatory diseases. In the present study, the authors investigated to examine the prognostic significance of various plasma biomarkers in patients with known or suspected coronary artery disease. However, they only measured hemoglobin levels. They did not measure other factors including iron, vitamin B12, folate, and platelet count. In this study, because of all these causes, high RDW levels are unavailable as an independent predictor of mortality in patients with acute coronary syndromes.

Relations between haemoglobin mass, cardiac dimensions and aerobic capacity in endurance trained cyclists

AIM

Chronic endurance exercise triggers increased cardiac dimensions, blood volumes and haemoglobin mass (Hb mass). Cardiac output and Hb mass are considered as independent contributors to aerobic performance. Therefore, increased Hb mass could counterbalance for a relative deficiency in cardiac adaptation. The purpose of the present study is to investigate relations between Hb mass and cardiac dimensions in a group of endurance athletes with respect to aerobic capacity.

METHODS

Two groups of highly trained cyclists featuring high (HHB group, N.=13) and low (LHB group, N.=13) Hb mass (measured by a CO-rebreathing method) were compared for measures of aerobic performance, cardiac wall thickness, cavity size and left ventricular mass (determined by 2-D-echocardiography). Lean body mass (LBM) was chosen as anthropometrical reference for Hb mass.

RESULTS

HHB featured higher cardiac wall thickness than LHB, but no difference appeared in cardiac cavity size, left ventricular mass and the performance parameters. Normalising Hb mass for body weight instead of LBM improved correlations between Hb mass and performance parameters.

CONCLUSIONS

Our data provides new evidence for a connection between cardiac wall thickness and Hb mass in endurance athletes but no further evidence for a counterbalance between Hb mass and cardiac adaptation was found. Moreover, we postulate that Hb mass loses predictive value for aerobic performance when normalised for LBM.

A study of changes in red cell volume and haemoglobin concentration during phlebotomy induced iron deficiency and iron repletion using the Technicon H1

The recently introduced Technicon H1 analyser uses an improved optical principle to measure the size and haemoglobin concentration of erythrocytes. We have made a serial study of ten patients undergoing phlebotomy to induce mild iron deficiency. The instrument showed the early development of anisohypochromia with subsequent fall in the mean cell haemoglobin concentration (MCHC). Cell volume was preserved until relatively late and during early iron deficient erythropoiesis cell volume would appear to be maintained at the expense of haemoglobin concentration. The Technicon H6000 (conventional technology) used in parallel produced contrasting results indicating anisomicrocytosis with preservation of cell haemoglobin concentration until relatively late. Five cases of severe iron deficiency treated with iron were similarly studied and showed comparable changes on both instruments, with characteristically bimodal cell volume histograms and large increases in red cell distribution width. Our results indicate that the new generation of instruments will generate red cell data of additional clinical value.

The Role of the Kidney in Blood Volume Regulation: The Kidney as a Regulator of the Hematocrit

The kidney plays a pivotal role in the regulation of blood volume by controlling the plasma volume and red blood cell (RBC) mass. Further, it is proposed that the kidney coordinates the relative volumes of these 2 blood components and in so doing regulates the hematocrit. This novel function as proposed is a functional concept whereby the kidney does not simply produce erythropoietin, but that the kidney regulates the hematocrit is termed the critmeter function. The kidney is unique in that it can indirectly report on blood volume as a tissue oxygen signal. It is proposed that the kidneys detect small changes in tissue oxygen tension for erythropoietin production at the critmeter, a functional unit of marginal oxygen tension within the kidneys. As the production of erythropoietin is modulated by angiotensin II, the renin-angiotensin system entrains the production of erythropoietin as part of the effector signals of the feedback loop of blood volume regulation. Collectively, the consideration of these points generates a paradigm shift in our understanding of blood volume regulation in that the role of the kidney may be expanded from simply "producing" erythropoietin to regulating the hematocrit. Further, this concept broadens the scope of the traditionally identified effector mechanisms of plasma volume regulation to include the modulation of erythropoietin production and hence RBC mass. The inclusion of both plasma volume and RBC mass as factors targeted by the effector signals recapitulates that whole blood volume is sensed and reported in the afferent signals. In summary, distinct sensing and effector mechanisms for regulating the volume of the two components of whole blood (plasma and red cell mass) are recognized. The coupling of the regulation of these 2 components of blood volume is highlighted.

Lack of evidence of hypervolemia in children with insulin-dependent diabetes mellitus

Hypervolemia is considered to play a major role in the pathogenesis of diabetic vasculo- and nephropathy. The aim of our study is to determine whether children and adolescents with insulin-dependent diabetes mellitus (IDDM) experience alterations in blood volume (BV) before onset of apparent nephropathy. BV (calculated as the sum of measured plasma volume (PV) and red cell volume (RCV)) was determined in 31 children (9-16 yr) with a mean duration of IDDM of 6.6 yr and without microalbuminuria. Due to dependence of these values on age, size and sex, all data were normalised for body size parameters. While no statistical difference for BV normalised for lean body mass (LBM) (86.98+/-9.5 ml/kg) was found in diabetic children compared with our control population (84.91+/-12.08 ml/kg), a difference could be shown when normalised for body surface area (BSA) (diabetic children 2.37+/-0.3 L/m(2); control population 2.15+/-0.38 L/m(2), p=0.002). Increased BV is only present when normalising for BSA and not for the theoretical superior LBM-index. Because the study population exhibited a poor glycemic control (HbA1c 10.2+/-2.4 %), an influence of glucosuria-induced polyuria on BV cannot be excluded. Taking into account these limitations our data do not confirm the presence of hypervolemia before onset of diabetic nephropathy.

Increased serum erythropoietin but not red cell production after 4 wk of intermittent hypobaric hypoxia (4,000-5,500 m)

This study tested the hypothesis that athletes exposed to 4 wk of intermittent hypobaric hypoxia exposure (3 h/day, 5 days/wk at 4,000-5,500 m) or double-blind placebo increase their red blood cell volume (RCV) and hemoglobin mass (Hbmass) secondary to an increase in erythropoietin (EPO). Twenty-three collegiate level athletes were measured before (Pre) and after (Post) the intervention for RCV via Evans blue (EB) dye and in duplicate for Hbmass using CO rebreathing. Hematological indexes including EPO, soluble transferrin receptor, and reticulocyte parameters were measured on 8-10 occasions spanning the intervention. The subjects were randomly divided among hypobaric hypoxia (Hypo, n = 11) and normoxic (Norm, n = 12) groups. Apart from doubling EPO concentration 3 h after hypoxia there was no increase in any of the measures for either Hypo or Norm groups. The mean change in RCV from Pre to Post for the Hypo group was 2.3% (95% confidence limits = -4.8 to 9.5%) and for the Norm group was -0.2% (-5.7 to 5.3%). The corresponding changes in Hbmass were 1.0% (-1.3 to 3.3%) for Hypo and -0.3% (-2.6 to 3.1%) for Norm. There was good agreement between blood volume (BV) from EB and CO: EB BV = 1.03 x CO BV + 142, r2 = 0.85, P < 0.0001. Overall, evidence from four independent techniques (RCV, Hbmass, reticulocyte parameters, and soluble transferrin receptor) suggests that intermittent hypobaric hypoxia exposure did not accelerate erythropoiesis despite the increase in serum EPO.

Red cell macrocytosis in COPD patients without respiratory insufficiency: a brief report

Red cell macrocytosis has been frequently described in hypoxemic patients with chronic obstructive pulmonary disease (COPD). However, macrocytosis is not related to hyoxemia. The objective of this study was to determine the frequency of macrocytosis (defined as mean corpuscular volume (MCV) higher than 94fl) in stable COPD patients without respiratory insufficiency, and to analyze the possible relationship between its presence and clinical and functional parameters. Fifty-eight consecutive patients with COPD, and without other significant comorbid conditions, were included in the study. Macrocytosis was present in 17 of the 58 stable COPD patients (29%). The differences between patients with and without macrocytosis were not statistically significant, except for MCV. In the subgroup of 36 ex-smoker COPD patients, macrocytosis was present in nine patients (25%). In this subgroup, MCV significantly correlated with dyspnea (r=0.36, P=0.03) and forced expiratory volume in 1s (FEV(1)) (r=-0.35, P=0.03). We conclude that macrocytosis is a frequent finding in stable non-hypoxemic COPD patients, and that in ex-smoker patients the degree of macrocytosis is associated with a worse clinical situation in terms of dyspnea and FEV(1).

Live high-train low for 24 days increases hemoglobin mass and red cell volume in elite endurance athletes

The effect of live high-train low on hemoglobin mass (Hbmass) and red cell volume (RCV) in elite endurance athletes is still controversial. We expected that Hbmass and RCV would increase, when using a presumably adequate hypoxic dose. An altitude group (AG) of 10 Swiss national team orienteers (5 men and 5 women) lived at 2,500 m (18 h per day) and trained at 1,800 and 1,000 m above sea level for 24 days. Before and after altitude, Hbmass, RCV (carbon monoxide rebreathing method), blood, iron, and performance parameters were determined. Seven Swiss national team cross-country skiers (3 men and 4 women) served as “sea level” (500–1,600 m) control group (CG) for the changes in Hbmass and RCV. The AG increased Hbmass (805 ± 209 vs. 848 ± 225 g; P < 0.01) and RCV (2,353 ± 611 vs. 2,470 ± 653 ml; P < 0.01), whereas there was no change for the CG (Hbmass: 849 ± 197 vs. 858 ± 205 g; RCV: 2,373 ± 536 vs. 2,387 ± 551 ml). Serum erythropoietin ( P < 0.001), reticulocytes ( P < 0.001), transferrin ( P < 0.001), soluble transferrin receptor ( P < 0.05), and hematocrit ( P < 0.01) increased, whereas ferritin ( P < 0.05) decreased in the AG. These changes were associated with an increased maximal oxygen uptake (3,515 ± 837 vs. 3,660 ± 770 ml/min; P < 0.05) and improved 5,000-m running times (1,098 ± 104 vs. 1,080 ± 98 s; P < 0.01) from pre- to postaltitude. Living at 2,500 m and training at lower altitudes for 24 days increases Hbmass and RCV. These changes may contribute to enhance performance of elite endurance athletes.

Splenectomy impairs diffusive oxygen transport in the lung of dogs

The spleen acts as an erythrocyte reservoir in highly aerobic species such as the dog and horse. Sympathetic-mediated splenic contraction during exercise reversibly enhances convective O2 transport by increasing hematocrit, blood volume, and O2-carrying capacity. Based on theoretical interactions between erythrocytes and capillary membrane (Hsia CCW, Johnson RL Jr, and Shah D. J Appl Physiol 86: 1460-1467, 1999) and experimental findings in horses of a postsplenectomy reduction in peripheral O2-diffusing capacity (Wagner PD, Erickson BK, Kubo K, Hiraga A, Kai M, Yamaya Y, Richardson R, and Seaman J. Equine Vet J 18, Suppl: 82-89, 1995), we hypothesized that splenic contraction also augments diffusive O2 transport in the lung. Therefore, we have measured lung diffusing capacity (DL(CO)) and its components during exercise by a rebreathing technique in six adult foxhounds before and after splenectomy. Splenectomy eliminated exercise-induced polycythemia, associated with a 30% reduction in maximal O2 uptake. At any given pulmonary blood flow, DL(CO) was significantly lower after splenectomy owing to a lower membrane diffusing capacity, whereas pulmonary capillary blood volume changed variably; microvascular recruitment, indicated by the slope of the increase in DL(CO) with respect to pulmonary blood flow, was also reduced. We conclude that splenic contraction enhances both convective and diffusive O2 transport and provides another compensatory mechanism for maintaining alveolar O2 transport in the presence of restrictive lung disease or ambient hypoxia.

Live high-train low associated with increased haemoglobin mass as preparation for the 2003 World Championships in two native European world class runners

BACKGROUND

It is unclear whether world class endurance athletes, in contrast with less well trained subjects, increase their haemoglobin mass on a regimen of living high and training low (LHTL).

OBJECTIVE

To assess whether haemoglobin mass increases in world class athletes on LHTL and whether this increase is associated with peak performance at a subsequent important competition.

METHODS

Two Swiss world class runners (one 5000 m and one marathon) lived for 26 days (18 hours a day) at an altitude of 2456 m and trained at 1800 m. This LHTL camp was the preparation for the World Athletic Championships taking place 27-29 days after the end of the camp. Haemoglobin mass and other haematological variables were measured before and after the LHTL camp. The performance parameter was the race times during that period.

RESULTS

Haemoglobin mass increased by 3.9% and 7.6%, and erythrocyte volume by 5.8% and 6.3%. The race times, as well as the ranking at the World Championships, indicated clearly improved performance after the LHTL camp.

CONCLUSIONS

The results suggest that LHTL with an adequate dose of hypoxia can increase haemoglobin mass even in world class athletes, which may translate into improved performance at important competitions at sea level.

A three-week traditional altitude training increases hemoglobin mass and red cell volume in elite biathlon athletes

It is well known that altitude training stimulates erythropoiesis, but only few data are available concerning the direct altitude effect on red blood cell volume (RCV) in world class endurance athletes during exposure to continued hypoxia. The purpose of this study was to evaluate the impact of three weeks of traditional altitude training at 2050 m on total hemoglobin mass (tHb), RCV and erythropoietic activity in highly-trained endurance athletes. Total hemoglobin mass, RCV, plasma volume (PV), and blood volume (BV) from 6 males and 4 females, all members of a world class biathlon team, were determined on days 1 and 20 during their stay at altitude as well as 16 days after returning to sea-level conditions (800 m, only males) by using the CO-rebreathing method. In males tHb (14.0 +/- 0.2 to 15.3 +/- 1.0 g/kg, p < 0.05) and RCV (38.9 +/- 1.5 to 43.5 +/- 3.9 ml/kg, p < 0.05) increased at altitude and returned to near sea-level values 16 days after descent. Similarly in females, tHb (13.0 +/- 1.0 to 14.2 +/- 1.3 g/kg, p < 0.05) and RCV (37.3 +/- 3.3 to 42.2 +/- 4.1 ml/kg, p < 0.05) increased. Compared to their sea-level values, the BV of male and female athletes showed a tendency to increase at the end of the altitude training period, whereas PV was not altered. In male athletes, plasma erythropoietin concentration increased up to day 4 at altitude (11.8 +/- 5.0 to 20.8 +/- 6.0 mU/ml, p < 0.05) and the plasma concentration of the soluble transferrin receptor was elevated by about 11 % during the second part of the altitude training period, both parameters indicating enhanced erythropoietic activity. In conclusion, we show for the first time that a three-week traditional altitude training increases erythropoietic activity even in world class endurance athletes leading to elevated tHb and RCV. Considering the relatively fast return of tHb and RCV to sea-level values after hypoxic exposure, our data suggest to precisely schedule training at altitude and competition at sea level.

Terminal complement complex in septic shock with capillary leakage: marker of complement activation?

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the value of terminal complement complex (C5b-9) plasma levels as a marker for complement activation in septic shock with concomitant capillary leak syndrome.

METHODS

In a prospective animal study 10 fasted, anaesthetized, mechanically ventilated and multi-catheterized pigs (20.6 +/- 1.3 kg) were investigated over a period of 8 h. Sepsis was induced by faecal peritonitis (1 g kg(-1) body weight faeces, n = 5) and compared to controls (n = 5). The animals received 6% hydroxyethyl starch 200/0.5 to maintain a central venous pressure of 12 mmHg. To quantify capillary leak syndrome, albumin escape rate was measured using 99mTc-labelled human serum albumin. Plasma levels of terminal complement complex were measured in a double antibody immunoassay (neoepitope-specific MoAb aE 11 as catching antibody). Immunohistological studies of renal specimens were performed to detect terminal complement complex deposition.

RESULTS

Albumen escape rate increased in septic animals (+ 52%) compared to controls (+ 3%, P < 0.05). Plasma levels of terminal complement complex decreased during the study period in both groups. In septic animals this finding was accompanied by a significant deposition of terminal complement complex in renal specimens (P < 0.05).

CONCLUSION

We found an activation of the complement system proven by marked deposition of terminal complement complex in renal specimen, while its plasma levels decreased during the study period in septic and control animals. These results suggest that in septic shock with capillary leak syndrome plasma level of terminal complement complex may not be a reliable marker of complement activation.

Individual variation in the erythropoietic response to altitude training in elite junior swimmers

OBJECTIVES

Inter-individual variations in sea level performance after altitude training have been attributed, at least in part, to an inter-individual variability in hypoxia induced erythropoiesis. The aim of the present study was to examine whether the variability in the increase in total haemoglobin mass after training at moderate altitude could be predicted by the erythropoietin response after 4 h exposure to normobaric hypoxia at an ambient Po(2) corresponding to the training altitude.

METHODS

Erythropoietin levels were measured in 16 elite junior swimmers before and after 4 h exposure to normobaric hypoxia (Fio(2) 0.15, approximately 2500 m) as well as repeatedly during 3 week altitude training (2100-2300 m). Before and after the altitude training, total haemoglobin mass (CO rebreathing) and performance in a stepwise increasing swimming test were determined.

RESULTS

The erythropoietin increase (10-185%) after 4 h exposure to normobaric hypoxia showed considerable inter-individual variation and was significantly (p<0.001) correlated with the acute erythropoietin increase during altitude training but not with the change in total haemoglobin mass (significant increase of approximately 6% on average). The change in sea level performance after altitude training was not related to the change in total haemoglobin mass.

CONCLUSIONS

The results of the present prospective study confirmed the wide inter-individual variability in erythropoietic response to altitude training in elite athletes. However, their erythropoietin response to acute altitude exposure might not identify those athletes who respond to altitude training with an increase in total haemoglobin mass.

The fluidity of blood in African elephants (Loxodonta africana)

The large cellular volume of erythrocytes and the increased plasma concentration of proteins in elephants are factors which potentially affect blood rheology adversely. To verify blood rheology, routine hemorheologic variables were analyzed in four African elephants (Loxodonta africana), housed in the zoo of Vienna. Whole blood viscosity at three different shear rates (WBV at low shear rate: WBV 0.7 s(-1) and WBV 2.4 s(-1); WBV at high shear rate: WBV 94 s(-1) done by LS30, Contraves) and erythrocyte aggregation (aggregation indices AI by LS30; aggregation indices M0, M1 by Myrenne aggregometer) were high (WBV 94 s(-1): 5.368 (5.246/5.648); WBV 2.4 s(-1): 16.291 (15.605/17.629); WBV 0.7 s(-1): 28.28 (25.537/32.173) mPa s; AI 2.4 s(-1): 0.25 (0.23/0.30); AI 0.7 s(-1): 0.24 (0.23/0.28); M0: 7.8 (6.4/8.4); M1: 30.2 (25/31)). Plasma viscosity (PV) was increased as well (1.865 (1.857/1.912) mPa s) compared to other mammalian species. These parameters would indicate a decrease in blood fluidity in elephants. However, erythrocyte rigidity (LORCA, Mechatronics) was decreased, which in contrast, has a promotive effect on peripheral perfusion. Blood rheology of the elephants was determined by a high whole blood and plasma viscosity as the result of pronounced erythrocyte aggregation and high plasma protein concentration. Thus, in the terminal vessels the resistance to flow will be increased. The large erythrocytes, which might impede blood flow further due to geometrical reasons, however, had a pronounced flexibility. We conclude that the effect of the increased inner resistance to peripheral blood flow was counteracted by the decreased rigidity of the erythrocytes to enable an adequate blood flow in African elephants.

Blood profile of pigeons (Columba livia) during growth and breeding

Changes in the blood profile of domestic pigeons (Columba livia) were studied during growth and breeding cycle. Counts of erythrocytes and leucocytes, and values of mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), blood volume, plasma volume (BV), width of erythrocytes, and length, width and volume of erythrocyte nuclei of squabs almost reached adult values by the 4th week of age. During courtship and mating, while the level of plasma glucose increased, those of albumin, potassium, cholesterol, calcium and uric acid decreased. At nest-building, plasma albumin and plasma calcium increased significantly. The initial phase of incubation showed an elevation in plasma calcium and a decline in cholesterol and sodium, whereas mid-phase of incubation indicated a marked rise in cholesterol and uric acid. Terminal phase of incubation had significantly low plasma protein level. During feeding and brooding period, a significant rise in sodium, protein and glucose levels and a fall in calcium were observed. Following egg-laying, there was a significant rise in calcium and a drop in protein, haemoglobin, cholesterol, sodium and MCH values. Concomitant with the phenomenal rate of growth of squabs, their haematological indices neared adult values by the 4th week of age and during breeding activity significant changes in blood values occurred.