[Effect of 99mTc elution in vivo from red cells on red cell volumes measured using autologous 99mTc-labeled red cells: comparison with 51Cr method]. / Effet de l'élution in vivo du technétium sur les volumes globulaires mesurés à l'aide d'hématies autologues marquées au 99mTc : comparaison avec la technique au 51Cr.

The purpose of this work was to compare the measured red-cell volume (RCV) using sodium pertechnétate [RCV-99mTc] compared to the reference technique using sodium radiochromate [RCV-51Cr] and to assess the influence of technetium-99 elution on the RCV-99mTc value. Ten patients had simultaneous measurements of RCV-99mTc and RCV-51Cr. Elution of Tc-99m from red blood cells was 2.9% and led to an average overestimation of RCV-99mTc of 3.7%. The introduction of individual tracer elution rates in the RCV-99mTc calculation corrects this overestimation.

RhEPO improves time to exhaustion by non-hematopoietic factors in humans.

PURPOSE: Erythropoietin (EPO) controls red cell volume (RCV) and plasma volume (PV). Therefore, injecting recombinant human EPO (rhEPO) increases RCV and most likely reduces PV. RhEPO-induced endurance improvements are explained by an increase in blood oxygen (O2) transport capacity, which increases maximum O2 uptake ([Formula: see text]O2max). However, it is debatable whether increased RCV or [Formula: see text]O2max are the main reasons for the prolongation of the time to exhaustion (t lim) at submaximal intensity. We hypothesized that high rhEPO doses in particular contracts PV such that the improvement in t lim is not as strong as at lower doses while [Formula: see text]O2max increases in a dose-dependent manner. METHODS: We investigated the effects of different doses of rhEPO given during 4 weeks [placebo (P), low (L), medium (M), and high (H) dosage] on RCV, PV, [Formula: see text]O2max and t lim in 40 subjects. RESULTS: While RCV increased in a dose-dependent manner, PV decreased independent of the rhEPO dose. The improvements in t lim (P +21.4 ± 23.8%; L +16.7 ± 29.8%; M +44.8 ± 62.7%; H +69.7 ± 73.4%) depended on the applied doses (R (2) = 0.89) and clearly exceeded the dose-independent [Formula: see text]O2max increases (P -1.7 ± 3.2%; L +2.6 ± 6.8%; M +5.7 ± 5.1 %; H +5.6 ± 4.3 %) after 4 weeks of rhEPO administration. Furthermore, the absolute t lim was not related (R (2) ≈ 0) to RCV or to [Formula: see text]O2max. CONCLUSIONS: We conclude that a contraction in PV does not negatively affect t lim and that rhEPO improves t lim by additional, non-hematopoietic factors.

Single perioperative dose of tranexamic acid in primary hip and knee arthroplasty.

INTRODUCTION: Tranexamic acid (TXA) is an antifibrinolytic agent that competitively inhibits the activation of plasminogen to plasmin. It has been shown to reduce blood loss in trauma and other haemorrhagic conditions and has recently been utilised in elective orthopaedic surgery. There are various methods of administering TXA described in the literature. METHODS: This retrospective cohort study reviews the effects of a single perioperative 1 g intravenous bolus on patients undergoing primary hip and knee arthroplasty and its effect on operative blood loss. After excluding patients who did not fulfil our inclusion criteria, a total of 110 patients were included in this study. Fifty underwent primary hip arthroplasty (30 treated with TXA; 60.0 %), and 60 underwent primary knee arthroplasty (29 treated with TXA; 48.3 %). The main outcome measure was red cell volume and total blood loss, and secondary measures were needed for blood transfusions, presence of thromboembolic events, and length of hospital stay. RESULTS: Both cohorts who received TXA showed a reduction in immediate postoperative red cell volume loss and total blood loss (p < 0.01). There was no association with the administration of TXA and the rate of postoperative blood transfusions (hip p = 0.36, knee p = 0.13), incidence of symptomatic deep vein thrombosis (hip p = 0.36, knee p = 0.31), or postoperative hospital length of stay (hip p = 0.70, knee p = 0.68). CONCLUSION: This study demonstrates that a single perioperative bolus of intravenous TXA may significantly reduce operative blood loss in both primary total hip and knee arthroplasty in a cost-effective manner, in combination with meticulous perioperative haemostasis.

Red blood cells of sickle cell disease patients exhibit abnormally high abundance of N-methyl D-aspartate receptors mediating excessive calcium uptake.

Recently we showed that N-methyl D-aspartate receptors (NMDARs) are expressed in erythroid precursors (EPCs) and present in the circulating red blood cells (RBCs) of healthy humans, regulating intracellular Ca(2+) in these cells. This study focuses on investigating the possible role of NMDARs in abnormally high Ca(2+) permeability in the RBCs of patients with sickle cell disease (SCD). Protein levels of the NMDAR subunits in the EPCs of SCD patients did not differ from those in EPCs of healthy humans. However, the number and activity of the NMDARs in circulating SCD-RBCs was substantially up-regulated, being particularly high during haemolytic crises. The number of active NMDARs correlated negatively with haematocrit and haemoglobin levels in the blood of SCD patients. Calcium uptake via these non-selective cation channels was induced by RBC treatment with glycine, glutamate and homocysteine and was facilitated by de-oxygenation of SCD-RBCs. Oxidative stress and RBC dehydration followed receptor stimulation and Ca(2+) uptake. Inhibition of the NMDARs with an antagonist memantine caused re-hydration and largely prevented hypoxia-induced sickling. The EPCs of SCD patients showed higher tolerance to memantine than those of healthy subjects. Consequently, NMDARs in the RBCs of SCD patients appear to be an attractive target for pharmacological intervention.

P2X receptor stimulation amplifies complement-induced haemolysis.

Activation of the complement system evokes cell damage by insertion of membrane attack complexes, which constitute the basis of the pathogenesis of various haemolytic disorders. Recently, we found that haemolysis caused by other types of membrane pore-forming proteins such as α-haemolysin (HlyA) from Escherichia coli, α-toxin from Staphylococcus aureus and leukotoxin from Aggregatibacter actinomycetemcomitans inflict their cytotoxic effects through P2 receptor activation. Here we show that similar to haemolysis induced by HlyA, leukotoxin and α-toxin, complement-induced haemolysis is amplified through ATP release and subsequent P2 receptor activation. Similar results were found both in murine, sensitised ovine and human erythrocytes, with either human plasma or guinea pig serum as complement donors. Non-selective P2 antagonists (PPADS and suramin) concentration-dependently inhibited complement-induced haemolysis. More specific P2 receptor antagonists imply that P2X1 and P2X7 are the main receptors involved in this response. Moreover, complement activation produces a sustained increase in [Ca(2+)]i, which initially triggers significant erythrocyte shrinkage, most likely mediated by KCa3.1-dependent K(+) efflux. These results indicate that complement, similar to HlyA and α-toxin, requires purinergic signalling for full haemolysis and that activation of erythrocyte volume regulation protracts the process. This finding points to several new pathways to interfere with haemolytic diseases and implies that P2 receptor antagonists potentially can be used to prevent intravascular haemolysis.

Increased mean corpuscular volume of red blood cells predicts response to metronomic capecitabine and cyclophosphamide in combination with bevacizumab.

BACKGROUND: There is an urgent need for the identification of commonly assessable predictive factors in the treatment of patients with metastatic breast cancer. METHODS: During the course of a treatment including low dose metronomic oral cyclophosphamide and capecitabine plus i.v. bevacizumab (plus erlotinib in one third of the patients) for metastatic breast cancer, we observed that a relevant number of patients developed repeatedly elevated levels of mean corpuscular volume (MCV) of red blood cells without a significant fall in hemoglobin levels. We conducted a retrospective analysis on these 69 patients to evaluate if the increase in MCV could be associated to tumor response. RESULTS: During the course of treatment 42 out of 69 patients (61%) developed macrocytosis. Using Cox proportional hazards modeling that incorporated macrocytosis (MCV ≥ 100 fl) as a time-dependent covariate, macrocytosis resulted in a halved risk of disease progression (HR 0.45; 95% CI, 0.22-0.92, p-value 0.028). In a landmark analysis limited to patients with no sign of progression after 24 weeks of treatment, median time to progression was 72 weeks (48 weeks after landmark) in patients who had developed macrocytosis, and 43 weeks (19 weeks after landmark) in patients who had not (p=0.023). CONCLUSION: Macrocytosis inversely related to risk of disease progression in patients treated with metronomic capecitabine plus cyclophosphamide and bevacizumab for metastatic breast cancer. This finding may be explained through thymidylate synthase inhibition by capecitabine. Whether bevacizumab has a role in determining macrocytosis, similarly to what happens with sunitinib, has to be further investigated. If other studies will confirm our findings, macrocytosis might be used as an early marker of response during metronomic treatment with capecitabine and cyclophosphamide with or without bevacizumab.

Lack of association between elevated mean red cell volume and haematological toxicity in patients receiving long-term methotrexate for rheumatoid arthritis.

AIMS: It has been suggested that elevated mean red cell volume (MCV) may be a predictor of haematological toxicity in rheumatoid arthritis (RA) patients receiving methotrexate (MTX). We wished to identify whether there was an association between MCV, red cell folate and haematological toxicity in patients on MTX monotherapy for the long-term management of RA. METHODS: Evidence of haematological toxicity was sought by note review of patients recruited in a cross-sectional study of MTX monotherapy in RA. Retrospective data included MCVs from before MTX initiation and after 3 and 6 months of treatment. Data were collected prospectively every 6 months for up to 2 years after enrolment. Any record of cytopenia or the development of haematological malignancy was recorded from commencement of MTX until the present day. Red cell folate concentrations were tested on enrolment to the study. RESULTS: A total of 165 patients was included, 74.5% female, median disease duration 7 years (range 3 months-57 years). The median duration of MTX treatment was 74.9 months (range 10-241 months) giving 1030.2 patient-years of MTX exposure. Twenty-four patients (14.5%) had a MCV > 98 fL on study entry. Evidence of haematological abnormality was found in six patients (3.6%); chronic lymphocytic leukaemia (1), persistent lymphocytosis (1), persistent monocytosis (1) and neutropenia (3). There was no association between red cell folate or MCV and haematological toxicity. CONCLUSION: Neutropenia and pancytopenia are rare side-effects of MTX therapy in this cohort. Elevated MCV or low mean red cell folate does not appear to be associated with haematological malignancy or toxicity in this cohort of patients on long-term MTX therapy.

Alterations of systemic and muscle iron metabolism in human subjects treated with low-dose recombinant erythropoietin.

The high iron demand associated with enhanced erythropoiesis during high-altitude hypoxia leads to skeletal muscle iron mobilization and decrease in myoglobin protein levels. To investigate the effect of enhanced erythropoiesis on systemic and muscle iron metabolism under nonhypoxic conditions, 8 healthy volunteers were treated with recombinant erythropoietin (rhEpo) for 1 month. As expected, the treatment efficiently increased erythropoiesis and stimulated bone marrow iron use. It was also associated with a prompt and considerable decrease in urinary hepcidin and a slight transient increase in GDF-15. The increased iron use and reduced hepcidin levels suggested increased iron mobilization, but the treatment was associated with increased muscle iron and L ferritin levels. The muscle expression of transferrin receptor and ferroportin was up-regulated by rhEpo administration, whereas no appreciable change in myoglobin levels was observed, which suggests unaltered muscle oxygen homeostasis. In conclusion, under rhEpo stimulation, the changes in the expression of muscle iron proteins indicate the occurrence of skeletal muscle iron accumulation despite the remarkable hepcidin suppression that may be mediated by several factors, such as rhEpo or decreased transferrin saturation or both.

Effect of complete protein 4.1R deficiency on ion transport properties of murine erythrocytes.

Moderate hemolytic anemia, abnormal erythrocyte morphology (spherocytosis), and decreased membrane stability are observed in mice with complete deficiency of all erythroid protein 4.1 protein isoforms (4.1(-/-); Shi TS et al. J Clin Invest 103: 331, 1999). We have examined the effects of erythroid protein 4.1 (4.1R) deficiency on erythrocyte cation transport and volume regulation. 4.1(-/-) mice exhibited erythrocyte dehydration that was associated with reduced cellular K and increased Na content. Increased Na permeability was observed in these mice, mostly mediated by Na/H exchange with normal Na-K pump and Na-K-2Cl cotransport activities. The Na/H exchange of 4.1(-/-) erythrocytes was markedly activated by exposure to hypertonic conditions (18.2 +/- 3.2 in 4.1(-/-) vs. 9.8 +/- 1.3 mmol/10(13) cell x h in control mice), with an abnormal dependence on osmolality (EC(50) = 417 +/- 42 in 4.1(-/-) vs. 460 +/- 35 mosmol/kgH(2)O in control mice), suggestive of an upregulated functional state. While the affinity for internal protons was not altered (K(0.5) = 489.7 +/- 0.7 vs. 537.0 +/- 0.56 nM in control mice), the V(max) of the H-induced Na/H exchange activity was markedly elevated in 4.1(-/-) erythrocytes (V(max) 91.47 +/- 7.2 compared with 46.52 +/- 5.4 mmol/10(13) cell x h in control mice). Na/H exchange activation by okadaic acid was absent in 4.1(-/-) erythrocytes. Altogether, these results suggest that erythroid protein 4.1 plays a major role in volume regulation and physiologically downregulates Na/H exchange in mouse erythrocytes. Upregulation of the Na/H exchange is an important contributor to the elevated cell Na content of 4.1(-/-) erythrocytes.

Red cell mass responses to daily erythropoietin and iron injections in the ovine fetus.

OBJECTIVE: Anemic ovine fetuses supplemented with intra-amniotic iron undergo rapid expansion of red cell mass. The present study tested the hypothesis that nonanemic fetuses that were supplemented with daily intra-amniotic iron plus intravascular injections of erythropoietin would experience accelerated erythrocyte production. STUDY DESIGN: Nine late gestation ovine fetuses received 100 to 120 units of erythropoietin intravascularly plus 10 mg of iron intra-amniotically daily for 7 days (low erythropoietin dose group). Four additional fetuses received 1000 units of erythropoietin plus 10 mg iron daily for the same period (high erythropoietin dose group). Responses were compared with 9 nonsupplemented time-control fetuses. Statistical testing was by 3-factor repeated measures analysis of variance. RESULTS: Immediately after erythropoietin injection, plasma erythropoietin concentration was elevated approximately 25- and 250-fold in the low and high erythropoietin dose groups, respectively. Erythropoietin returned to basal levels by 24 hours after the injection. Plasma iron concentration increased in the low erythropoietin dose group but not in the control or high erythropoietin dose groups. Reticulocyte index increased in both erythropoietin supplemented groups but not in control fetuses. Hematocrit level increased above control by day 5 in the low erythropoietin dose group and by day 2 in the high erythropoietin dose group. Red cell mass increased significantly on supplement day 7 in the low erythropoietin dose group and on day 5 in the high erythropoietin dose group. Fetal blood gases and pH were unchanged with time in all 3 groups. CONCLUSION: Although daily combined erythropoietin and iron supplements in nonanemic ovine fetuses significantly increased circulating red cell mass in a dose-dependent manner, this increase was small relative to the rapid expansion of red cell mass previously observed after iron supplementation in fetuses with hemorrhage-induced anemia. We speculate that this difference in response may be due to a combination of rapid fetal clearance of erythropoietin plus a relative insensitivity to erythropoietin caused by the absence of other cytokines, which are elevated during fetal anemia.

Eritrocitos post trasplante renal y su tratamiento farmacológico: inhibidores de la enzima convertidora de angiotensina versus bloqueadores de los receptores de angiotensina en un caso / Treatment of post kidney transplantation erythrocytosis with angiotensin converting enzyme inhibitors or angiotensin receptor blockers: report of 1 case

A 35 years old male is presented. Eight months after receiving a renal allograft his hypertension worsened and his packed red cell volume raised to 53.7 percent. Enalapril was started and a 500 ml phlebotomy was performed. In three occasions packed red cell volumes decreased excessively and enalapril was discontinued. Finally, the drug was replaced with losartan, normalizing blood pressure values and stabilizing packed red cell volumes. This case illustrates the different reductions in packed red cell volumes induced by enalapril and losartan. These differences could have a therapeutic relevance

Comparison of detection sensitivity of immuno- and genotoxicological effects of subacute cypermethrin and permethrin exposure in rats.

Immuno- and genotoxicological effects of a 28-day oral treatment by equitoxic (1/10, 1/25, 1/50 LD50) doses of cypermethrin (55.4, 22.2, and 11.1 mg/kg) and permethrin (125.7, 50.3, and 12.6 mg/kg) were compared on male Wistar rats. Humoral and cell-mediated immunity were investigated by PFC assay and delayed type hypersensitivity (DTH) reaction (footpad swelling assay), and the genotoxic effects were studied by structural and numerical chromosome aberrations in bone marrow cells. The experimental system also involved certain general toxicological (body weight gain, organ weights) and haematological [white blood cell (WBC), red blood cell (RBC), haematocrit (Ht) and cell content of the femoral bone marrow] investigations. Among the immune function assays, only DTH reaction decreased at the two higher cypermethrin (CY) doses. These doses also increased the number of numerical chromosome aberrations of the bone marrow cells but did not change the number of structural aberrations. All CY doses decreased the mean cell volume (MCV) of RBCs and the Ht value. The two higher doses also reduced the WBC count in the peripheral blood. Permethrin (PE), in the applied dose range, had no effect on the examined immune function parameters, but all three doses increased the number of numerical chromosome aberrations. A dose-dependent increase in the liver weight, decreased MCV value, and elevated cell content of the femoral bone marrow were also observed. Under these experimental conditions, examination of chromosome aberrations proved to be less sensitive in detection of exposure by cypermethrin than applied immune function assays did. Permethrin, on the contrary, increased the number of numeric aberrations at all dose levels but had no effect on the immune function parameters examined.

The erythropoietic response to erythropoietin in patients with rheumatoid arthritis.

We studied whether orthopedic surgical patients with rheumatoid arthritis (RA) can generate an erythropoietic response to either endogenous erythropoietin or to recombinant human erythropoietin (EPO) therapy to the same extent as patients without rheumatoid arthritis (non-RA). Seventy patients (10 RA, 60 non-RA) were entered into clinical trials of aggressive autologous blood donation before elective orthopedic surgery at one institution, randomized to receive EPO (600 U/kg, iv, 6 times over 3 weeks) or placebo. RA patients given EPO had red blood cell (RBC) production that was enhanced by 624 +/- 137 ml (mean +/- SD) as compared with 271 +/- 174 ml (p = 0.02) for RA patients given placebo treatment. Preoperative RBC volume expansion in 10 RA patients was 5.9 +/- 3.7 ml/kg as compared with 7.4 +/- 3.9 ml/kg for 60 non-RA patients (p = 0.13). RA patients can benefit to the same extent as non-RA patients from aggressive blood conservation programs that incorporate erythropoietin-modulated erythropoiesis.

Aspirin does not increase allogeneic blood transfusion in reoperative coronary artery surgery.

While preoperative aspirin (ASA) therapy does not increase allogeneic transfusion in elective primary coronary artery bypass grafting (CABG) operations, the impact of ASA consumption on transfusion in cardiac operations with greater risk of bleeding has not been investigated. We examined the influence of ASA consumption on mediastinal drainage and allogenic transfusion in 317 patients undergoing reoperative CABG surgery. Patients receiving ASA or ASA containing medications within 7 days preoperatively (n = 215) had similar perioperative characteristics but were older and had smaller red cell volumes than control patients not receiving ASA (n = 102). All patients received aminocaproic acid, but autotransfusion of mediastinal blood or platelet rich plasma, aprotinin, or desmopressin were not used. No significant differences were observed between ASA and control groups with respect to postoperative hematocrit, mediastinal drainage, frequency of reexploration for excessive bleeding, amount of allogeneic packed red blood cell, fresh frozen plasma, platelet concentrate or cryoprecipitate transfusion, or the fraction of patients receiving any allogeneic blood product. There was no difference in mediastinal drainage when stratified by timing of most recent ASA ingestion. Multiple linear regression identified duration of cardiopulmonary bypass (CPB), internal mammary artery harvesting, chronic preoperative steroid therapy and use of an intraaortic balloon pump (IABP) as significant predictors of mediastinal drainage. Logistic regression demonstrated that female gender, prolonged duration of CPB, advanced age, use of IABP, and a negative history of smoking were significant independent predictors of blood product transfusion. There was no significant interaction of preoperative heparin therapy with ASA on transfusion demonstrated by univariate or multivariate analyses. These results indicate that preoperative ASA ingestion is not an important determinant of mediastinal drainage or allogeneic transfusion, even after repeat CABG operations, and that surgical and patient characteristics are more important predictors of these outcomes.

Interferon treatment in polycythaemia vera.

Recent studies have shown rIFN alpha to be an effective agent in the management of polycythemia vera. Red cell mass can be controlled within 6 to 12 months, eliminating the need for phlebotomy in up to 70% of cases. In addition, significant improvement in the platelet counts, iron status, pruritus scores and the degree of splenomegaly have been reported. Most patients require between 9 and 25 x 10(6)U/week, although once the disease is under control it may be possible to reduce both the dose and frequency of administration. Side-effects remain a significant problem, occurring in over 30% of patients, and may be related to the high mean age of the patients. Long-term studies are now indicated to determine if the natural history of the disease is altered and whether, in particular, the incidence of myelofibrosis and/or leukaemic transformation is reduced.

Interleukin-6-associated anemia: determination of the underlying mechanism.

Recombinant human interleukin-6 (rhIL-6) is a pluripotent cytokine with proinflammatory, antitumor, and growth factor effects. Clinical investigations of rhIL-6 either alone as immunotherapy or as a colony-stimulating factor in conjunction with chemotherapy have shown a dose-dependent, rapid onset, and largely reversible decrease in venous hematocrit levels. In an effort to determine the mechanism for the rhIL-6-associated anemia, we measured red blood cell volume serially in patients receiving rhIL-6 at either 30 micrograms/kg/day as a 120-hour continuous intravenous infusion (renal cell carcinoma) or 100 micrograms/kg/d intravenously over 1 hour for 5 days (melanoma) as part of two separate phase II trials. Radioisotope dilution assays with 51Cr-labeled autologous red blood cells and hemolysis screens were performed on day 1 before the initiation of therapy and on day 5 shortly before the end of therapy. In the 6 patients studied, the mean decrease in hemoglobin concentration was 1.9 +/- 0.94 g/dL. The mean decrease in the hematocrit level was 6% +/- 2% and the mean increase in total blood volume was 731 +/- 337 mL. These changes were explained by a mean decrease in red blood mass of 106 +/- 109 mL and a mean increase in plasma volume of 743 +/- 289 mL. The decrease in red blood cell mass was largely explained by phlebotomy during the hospitalization, but was not statistically significant (paired t-test, P = .06). All other changes were statistically significant (P < .05). Simple regression analysis indicated that the decrease in hematocrit level and increase in plasma volume were related (y = -1.78 - .0066X; R = -.74). Measurements of lactate dehydrogenase, bilirubin, haptoglobin, and reticulocyte counts and serial stool hemoccults did not indicate hemolysis or blood loss. We conclude that the anemia caused by IL-6 is caused by an increase in plasma volume.