Raised haematocrit concentration and the risk of death and vascular complications after major surgery.

BACKGROUND: Preoperative anaemia is associated with adverse postoperative outcomes. Data on raised preoperative haematocrit concentration are limited. This study aimed to evaluate the effect of raised haematocrit on 30-day postoperative mortality and vascular events in patients undergoing major surgery. METHODS: This was a cohort study using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. Thirty-day mortality and vascular events, demographics and perioperative risk factors were obtained for adults undergoing major surgery. The adjusted effect of raised (over 0·50) compared with normal (0·41-0·50, American Medical Association reference range) preoperative haematocrit concentration on postoperative outcomes was assessed. Separate sex-specific analyses were also conducted, using haematocrit concentration thresholds commonly used in the diagnosis and management of apparent or absolute erythrocytosis. RESULTS: Some 3961 (2·0 per cent) of 197 469 patients had a raised haematocrit concentration before surgery. After adjustment, the 30-day postoperative mortality rate was higher in patients with raised haematocrit than in those without (odds ratio (OR) 2·23, 95 per cent confidence interval 1·77 to 2·80). Thirty-day rates of deep vein thrombosis (OR 1·95, 1·44 to 2·64) and pulmonary embolism (OR 1·79, 1·17 to 2·73), but not myocardial infarction or stroke, were also higher in patients with a raised haematocrit concentration. The effect on mortality was noted beyond the haematocrit thresholds of 0·48 in women and 0·52 in men; the effect estimates were considerably higher for values exceeding 0·54. Values between 0·41 and 0·45 were not associated with increased mortality risk. Similar observations were noted for venous thrombosis, although with apparent sex differences. CONCLUSION: A raised haematocrit concentration was associated with an increased risk of 30-day mortality and venous thrombosis following major surgery.

Efficacy and safety of deferasirox at low and high iron burdens: results from the EPIC magnetic resonance imaging substudy.

The effect of deferasirox dosing tailored for iron burden and iron loading based on liver iron concentration (LIC) was assessed over 1 year in less versus more heavily iron-overloaded patients in a substudy of the Evaluation of Patients' Iron Chelation with Exjade®. Deferasirox starting dose was 10-30 mg/kg/day, depending on blood transfusion frequency, with recommended dose adjustments every 3 months. Therapeutic goals were LIC maintenance or reduction in patients with baseline LIC <7 or ≥7 mg Fe/g dry weight (dw), respectively. Changes in LIC (R2-magnetic resonance imaging) and serum ferritin after 1 year were assessed. Adverse events (AEs) and laboratory parameters were monitored throughout. Of 374 patients, 71 and 303 had baseline LIC <7 and ≥7 mg Fe/g dw, respectively; mean deferasirox doses were 20.7 and 27.1 mg/kg/day (overall average time to dose increase, 24 weeks). At 1 year, mean LIC and median serum ferritin levels were maintained in the low-iron cohort (-0.02 ± 2.4 mg Fe/g dw, -57 ng/mL; P = not significant) and significantly decreased in the high-iron cohort (-6.1 ± 9.1 mg Fe/g dw, -830 ng/mL; P < 0.0001). Drug-related gastrointestinal AEs, mostly mild to moderate, were more frequently reported in the <7 versus ≥7 mg Fe/g dw cohort (39.4 versus 20.8 %; P = 0.001) and were not confounded by diagnosis, dosing, ethnicity, or hepatitis B and/or C history. Reported serum creatinine increases did not increase in low- versus high-iron cohort patients. Deferasirox doses of 20 mg/kg/day maintained LIC <7 mg Fe/g dw and doses of 30 mg/kg/day were required for net iron reduction in the high-iron cohort, with clinically manageable safety profiles. The higher incidence of gastrointestinal AEs at lower iron burdens requires further investigation.

Reversal of cardiac iron loading and dysfunction in thalassemic mice by curcuminoids.

Non-transferrin bound iron (NTBI) is found in plasma of ß-thalassemia patients and causes oxidative tissue damage. Cardiac siderosis and complications are the secondary cause of death in ß-thalassemia major patients. Desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) are promising chelators used to get negative iron balance and improve life quality. DFP has been shown to remove myocardial iron effectively. Curcuminoids (CUR) can chelate plasma NTBI, inhibit lipid peroxidation and alleviate cardiac autonomic imbalance. Effects of CUR on cardiac iron deposition and function were investigated in iron-loaded mice. Wild type ((mu)ß(+/+) WT) and heterozygous ß-knockout ((mu)ß(th-3/+) BKO) mice (C57BL/6) were fed with ferrocene-supplemented diet (Fe diet) and coincidently intervened with CUR and DFP for 2 months. Concentrations of plasma NTBI and malondialdehyde (MDA) were measured using HPLC techniques. Heart iron concentration was determined based on atomic absorption spectrophotometry and Perl's staining methods. Short-term electrocardiogram (ECG) was recorded with AD Instruments Power Lab, and heart rate variability (HRV) was evaluated using MATLAB 7.0 program. Fe diet increased levels of NTBI and MDA in plasma, nonheme iron and iron deposit in heart tissue significantly, and depressed the HRV, which the levels were higher in the BKO mice than the WT mice. CUR and DFP treatments lowered plasma NTBI as well as MDA concentrations (p <0.05), heart iron accumulation effectively, and also improved the HRV in the treated mice. The results imply that CUR would be effective in decreasing plasma NTBI and myocardial iron, alleviating lipid peroxidation and improving cardiac function in iron-loaded thalassemic mice.

Quality of life in thalassemia: a comparison of SF-36 results from the thalassemia longitudinal cohort to reported literature and the US norms.

Thalassemia is a chronic, inherited blood disorder, which, in its most severe form, causes life-threatening anemia. Advances in treatment have led to increased life expectancy however the need for chronic blood transfusions and chelation therapy remains a significant burden for patients. Our study compared health related quality of life (HRQOL) from the Thalassemia Clinical Research Network's (TCRNs) Thalassemia Longitudinal Cohort (TLC) study to US norms and assessed association with clinical variables. There were 264 patients over age 14 who completed the Medical Outcomes Study 36-Item Short Form Health Survey version 2 (SF36v2) baseline assessment. When compared to US norms, TLC patients had statistically significant (P < 0.05) worse HRQOL on five of the eight subscales (physical functioning, role-physical, general health, social functioning, and role-emotional) and on both summary scales (physical component summary and mental component summary). Women, older patients, and those with more disease complications and side effects from chelation reported lower HRQOL. In general, adolescents and adults with thalassemia report worse HRQOL than the US population, despite contemporary therapy. The SF-36 should become a standard instrument for assessing HRQOL in thalassemia to determine predictors of low HRQOL which may be better addressed by a multidisciplinary team.

Effects of green tea on iron accumulation and oxidative stress in livers of iron-challenged thalassemic mice.

Liver is affected by secondary iron overload in transfusions dependent b-thalassemia patients. The redox iron can generate reactive oxidants that damage biomolecules, leading to liver fibrosis and cirrhosis. Iron chelators are used to treat thalassemias to achieve negative iron balance and relieve oxidant-induced organ dysfunctions. Green tea (GT) (Camellia sinensis) catechins exhibit anti-oxidation, the inhibition of carcinogenesis, the detoxification of CYP2E1-catalyzed HepG2 cells and iron chelation. The purpose of this study was to investigate the effectiveness of GT in iron-challenged thalassemic mice. Heterozygous BKO type-thalassemia (BKO) mice (C57BL/6) experienced induced iron overload by being fed a ferrocene-supplemented diet (Fe diet) for 8 weeks, and by orally being given GT extract (300 mg/kg) and deferiprone (DFP) (50 mg/kg) for a further 8 weeks. Liver iron content (LIC) was analyzed by TPTZ colorimetric and Perl's staining techniques. Concentrations of liver reduced glutathione (GSH), collagen and malondialdehyde (MDA) were also measured. Dosages of the GT extract and DFP lowered LIC in the Fe diet-fed BKO mice effectively. The extract did not change any concentrations of liver glutathione, collagen and MDA in the BKO mice. Histochemical examination showed leukocyte infiltration in the near by hepatic portal vein and high iron accumulation in the livers of the iron-loaded BKO mice, however GT treatment lowered the elevated iron deposition. In conclusion, green tea inhibits or delays the deposition of hepatic iron in regularly iron-loaded thalassemic mice effectively. This will prevent the iron-induced generation of free radicals via Haber-Weiss and Fenton reactions, and consequently liver damage and fibrosis. Combined chelation with green tea would be investigated in beta-thalassemia patients with iron overload.

Cardiac T2* magnetic resonance for prediction of cardiac complications in thalassemia major.

BACKGROUND: The goal of this study was to determine the predictive value of cardiac T2* magnetic resonance for heart failure and arrhythmia in thalassemia major. METHODS AND RESULTS: We analyzed cardiac and liver T2* magnetic resonance and serum ferritin in 652 thalassemia major patients from 21 UK centers with 1442 magnetic resonance scans. The relative risk for heart failure with cardiac T2* values <10 ms (compared with >10 ms) was 160 (95% confidence interval, 39 to 653). Heart failure occurred in 47% of patients within 1 year of a cardiac T2* <6 ms with a relative risk of 270 (95% confidence interval, 64 to 1129). The area under the receiver-operating characteristic curve for predicting heart failure was significantly greater for cardiac T2* (0.948) than for liver T2* (0.589; P<0.001) or serum ferritin (0.629; P<0.001). Cardiac T2* was <10 ms in 98% of scans in patients who developed heart failure. The relative risk for arrhythmia with cardiac T2* values <20 ms (compared with >20 ms) was 4.6 (95% confidence interval, 2.66 to 7.95). Arrhythmia occurred in 14% of patients within 1 year of a cardiac T2* of <6 ms. The area under the receiver-operating characteristic curve for predicting arrhythmia was significantly greater for cardiac T2* (0.747) than for liver T2* (0.514; P<0.001) or serum ferritin (0.518; P<0.001). The cardiac T2* was <20 ms in 83% of scans in patients who developed arrhythmia. CONCLUSIONS: Cardiac T2* magnetic resonance identifies patients at high risk of heart failure and arrhythmia from myocardial siderosis in thalassemia major and is superior to serum ferritin and liver iron. Using cardiac T2* for the early identification and treatment of patients at risk is a logical means of reducing the high burden of cardiac mortality in myocardial siderosis. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00520559.

Efficacy of curcuminoids in alleviation of iron overload and lipid peroxidation in thalassemic mice.

Non-transferrin bound iron (NTBI) is detectable in plasma of beta-thalassemia patients and participates in free-radical formation and oxidative tissue damage. Desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) are iron chelators used for treatment of iron overload; however they may cause adverse effects. Curcuminoids (CUR) exhibits many pharmacological activities and presents beta-diketone group to bind metal ions. Iron-chelating capacity of CUR was investigated in thalassemic mice. The mice (C57BL/6 stain); wild type ((mu)beta(+/+)) and heterozygous beta-knockout ((mu)beta(th-3/+)) were fed with ferrocene-supplemented diet for 2 months, and coincidently intervened with CUR (200 mg/kg/day) and DFP (50 mg/kg/day). Plasma NTBI was quantified using NTA chelation/HPLC method, and MDA concentration was analyzed by TBARS-based HPLC. Hepatic iron content (HIC) and total glutathione concentration were measured colorimetrically. Tissue iron accumulation was determined by Perl's staining. Ferrocene-supplemented diet induced occurrence of NTBI in plasma of thalassemic mice as well as markedly increased iron deposition in spleen and liver. Treatment with CUR and DFP decreased levels of the NTBI and MDA effectively. Hepatic MDA and nonheme iron content was also decreased in liver of the treated mice whilst total glutathione levels were increased. Importantly, the CUR and DFP reduced liver weight index and iron accumulation. Clearly, CUR is effective in chelation of plasma NTBI in iron-loaded thalassemic mice. Consequently, it can alleviate iron toxicity and harmfulness of free radicals. In prospective, efficacy of curcumin in removal of labile iron pool (LIP) in hepatocytes and cardiomyocytes are essential for investigation.

Effect of green tea on iron status and oxidative stress in iron-loaded rats.

Plasma non-transferrin bound iron (NTBI) is potentially toxic and contributes to the generation of reactive oxygen species (ROS), consequently leading to tissue damage and organ dysfunction. Iron chelators and antioxidants are used for treatment of thalassemia patients. Green tea (GT) contains catechins derivatives that have many biological activities. The purpose of this study was to investigate the iron-chelating and free-radical scavenging capacities of green tea extract in vivo. Rats were injected ip with ferric citrate together with orally administered GT extract (GTE) for 4 months. Blood was collected monthly for measurement of iron overload and oxidative stress indicators. Plasma iron (PI) and total iron-binding capacity (TIBC) were quantified using bathophenanthroline method. Plasma NTBI was assayed with NTA chelation/HPLC. Plasma malonyldialdehyde (MDA) was determined by using the TBARS method. Erythrocyte oxidative stress was assessed using flow cytometry. Levels of PI, TIBC, NTBI and MDA, and erythrocyte ROS increased in the iron-loaded rats. Intervention with GT extract markedly decreased the PI and TIBC concentrations. It also lowered the transferrin saturation and effectively inhibited formation of NTBI. It also decreased the levels of erythrocyte ROS in week 4, 12 and 16. Therefore, green tea extract can decrease iron in plasma as well as eliminate lipid peroxidation in plasma, and destroy formation of erythrocyte ROS in the rats challenged with iron. The bifunctional effects could be beneficial in alleviating the iron and oxidative stress toxicity. In prospective, these GTE activities should be further examined in thalassemic animals or humans.

Curcumin contributes to in vitro removal of non-transferrin bound iron by deferiprone and desferrioxamine in thalassemic plasma.

Non-transferrin-bound iron (NTBI) is detectable in plasma of beta-thalassemia patients with transfusional iron overload. This form of iron may cause oxidative tissue damage and increased iron uptake, into several vital organs. Removal of NTBI species is incomplete and transient using standard intermittent desferrioxamine (DFO) or deferiprone (DFP) monotherapy. Combinations of these or other chelators may improve the protection time from NTBI and increase removal of harmful NTBI species. Curcuminoids from Curcuma longa L. is a naturally occurring phytochemical which shows a wide range of pharmacological properties including anti-oxidative, anti-inflammatory, anti-cancer and iron-chelating activities. In this study, the curcuminoids was investigated for NTBI chelation in thalassemic plasma in vitro and for the potential to improve NTBI removal when used with other chelators. Curcumin bound Fe(3+) to form a Fe(3+)-curcumin complex with a predominant absorption at 500 nm. The chemical binding of curcumin was dose- and time-dependent and more specific for Fe(3+) than Fe(2+). Using a HPLC-based NTBI assay without an aluminium blocking step, curcumin shuttled the iron from Fe(3+)-NTA complex, giving underestimated NTBI values. At equivalent concentrations DFO, DFP and curcumin decreased plasma NTBI with the order of DFP>DFO>curcumin. None of these chelators removed NTBI completely, but curcumin appeared to increase the rate of NTBI removal when added to DFP. It is proposed that the beta-diketo moiety of curcumin participates in the NTBI chelation.

Epigallocatechin-3-gallate and epicatechin-3-gallate from green tea decrease plasma non-transferrin bound iron and erythrocyte oxidative stress.

Beta-thalassemia patients suffer from secondary iron overload caused by increased iron absorption and multiple blood transfusions. Excessive iron catalyzes free-radical formation, causing oxidative tissue damage. Non-transferrin bound iron (NTBI) detected in thalassemic plasma is highly toxic and chelatable. Desferrioxamine and deferiprone are used to treat the iron overload, but many side effects are found. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) in green tea (GT) show strong antioxidant properties. We separated the EGCG and ECG from GT extract using an HPLC, and examined their iron-binding and free-radical scavenging activities. They bound Fe(3+) rapidly to form a complex with a predominant absorption at 560 nm. EGCG and ECG bound chemical Fe(3+) and chelated the NTBI in a time- and dose dependent manner. They also decreased oxidative stress in iron-treated erythrocytes. In conclusion, EGCG and ECG could be natural iron chelators that efficiently decrease the levels of NTBI and free radicals in iron overload.

Degenerative disc disease as a cause of back pain in the thalassaemic population: a case-control study using MRI and plain radiographs.

PURPOSE: The aim of this study was to test our observation that back pain in thalassemic patients could be caused by premature and extensive lumbar degenerative disc disease, when compared to non-thalassemic patients with back pain. METHODS AND MATERIALS: Sixteen thalassemic patients with their sex- and age-matched controls were recruited into the study, 12 with thalassemia major, and 4 with thalassemia intermedia. Both the thalassemia patients and control subjects suffered from back pain, which was subjective rather than measured/pain scored. All subjects underwent magnetic resonance (MR) imaging of the lumbar spine, and 11 of the cases and 8 controls had lumbar spine radiographs. Each lumbar disc was scored for radiographic appearances and MR features of disc degeneration and disc protrusion. Proportion values for these parameters and median scores were derived at each disc level, and were analyzed and compared. RESULTS: There was a statistically-significant difference between proportion values of cases and controls for the MR features (P value=0.01, n=16) and the radiographic features (P value=0.01, n=11 cases, n=8 controls) of disc degeneration. The median disc level scores for the thalassemic group were uniformly high across all lumbar discs, and at all levels except at L 4/5. The control group conversely demonstrated a predilection for disc degeneration at L4/5 level. CONCLUSION: The distribution of lumbar disc degeneration in thalassemic patients with back pain is more extensive, severe and multi-level in nature compared to matched controls, and disc degeneration should be considered as a significant cause of back pain in this population group.

Recent insights into interactions of deferoxamine with cellular and plasma iron pools: Implications for clinical use.

Despite the availability of deferoxamine (DFO) for more than three decades, its rates of interaction with cellular iron pools in different tissues, and the effects of its pharmacokinetics on the interaction with plasma iron pools, remain incompletely understood. The positive charge of DFO, together with the negative resting potential in vertebrate cells, favors cellular uptake, whereas the low lipophilicity and high molecular weight counter this effect. The findings presented suggest a facilitated uptake of DFO into hepatocytes, being several hundred-fold faster than into red cells. Antibodies that selectively recognize ferrioxamine (FO) show that initial hepatocellular iron chelation is cytosolic, but later transposes to lysosomal and ultimately canalicular compartments. Strong FO staining is visible in myocytes within 4-8 h after commencing a subcutaneous DFO infusion, indicating effective chelation of myocyte iron. A methodology was developed to study the interaction of DFO and its metabolites with plasma iron pools by stabilizing DFO with aluminum ions, thereby preventing iron shuttling from non-transferrin-bound iron (NTBI) onto DFO after plasma collection. DFO removes only about a third of NTBI rapidly, and NTBI is rarely cleared completely. Increasing DFO dosing does not increase NTBI removal, but instead leads to a greater rebound in NTBI on cessation of intravenous infusion. Thus, intermittent infusions of high-dose DFO are less desirable than continuous infusions at low doses, particularly in high-risk patients. Here the benefits of continuous DFO on heart function occur before changes in T2*-visible storage iron, consistent with early removal of a toxic labile iron pool within myocytes.

A retrospective observational study of pre-operative sickle cell screening.

The aim of this study was to determine the ethnic mix of those patients being pre-operatively screened for sickle cell disease in a London teaching hospital and to determine the rate of carriage of sickle haemoglobin amongst those tested. We retrospectively studied 1879 patients undergoing surgery over a 2-month period. Two hundred and thirteen (11%) were screened for sickle cell disease and of these, 12 (5%) tested positive for sickle cell trait (HbAS). There were no patients homozygous for sickle cell disease (HbSS) or with haemoglobin SC disease (HbSC). Screening rates varied widely in different ethnic groups from 0% of the Chinese population to 85.2% of the Afro-Caribbean population. We conclude that at present there is no coherent pre-operative screening policy for sickle cell disease in our institution. Sickle cell disease poses unique anaesthetic risks and with a rapidly expanding 'mixed race' population high-risk patients are difficult to identify phenotypically. We propose a universal screening policy be implemented in high-risk areas.

Cellular zinc content is a major determinant of iron chelator-induced apoptosis of thymocytes.

Desferrioxamine (DFO) and the hydroxypiridinone (HPO) deferiprone (CP20) chelate iron as well as other metals. These chelators are used clinically to treat iron overload, but they induce apoptosis in thymocytes. Thymocyte apoptosis is potentiated by zinc deficiency, suggesting that these iron chelators may induce apoptosis by depleting stores of zinc. Exposure of murine thymocytes to either DFO or deferiprone resulted in significant reductions in the labile intracellular zinc pool. Moreover, increasing intracellular zinc levels, by chronic zinc dietary supplementation to mice or in vitro loading with zinc, abrogated deferiprone-induced murine thymocyte apoptosis. Bidentate hydroxypyridinones such as deferiprone interact with intracellular zinc pools in a manner distinct from that of DFO, which is a hexadentate iron chelator. Whereas deferiprone acts synergistically with the zinc chelator NNNN-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) to induce apoptosis, DFO does not. This difference is most likely due to the ability of HPOs but not DFO to "shuttle" zinc onto acceptors such as metallothioneins. By nature of its structure, DFO is larger than deferiprone and is thus less able to access some intracellular zinc pools. Additionally, metal complexes of DFO are more stable than those of HPOs and thus are less likely to donate zinc to other acceptors. The ability of deferiprone to preferentially access zinc pools was also demonstrated by inhibition of a zinc-containing enzyme phospholipase C, particularly when combined with TPEN. These findings suggest that bidentate iron chelators access intracellular zinc pools not available to DFO and that zinc chelation is a mechanism of apoptotic induction by such chelators in thymocytes.

Structure-function investigation of the interaction of 1- and 2-substituted 3-hydroxypyridin-4-ones with 5-lipoxygenase and ribonucleotide reductase.

The structural and physiochemical properties of 3-hydroxypyridin-4-one chelators (HPOs) which influence inhibition of the iron-containing metalloenzymes ribonucleotide reductase (RR) and 5-lipoxygenase (5-LO) have been investigated. HPOs with substituents at the 1- and 2-positions of the pyridinone ring have been synthesized, and their inhibitory properties compared with those of desferrioxamine (DFO). Varying the alkyl substituents does not affect the affinity constant of these ligands for iron(III), but permits a systematic investigation of the effect of hydrophobicity and molecular shape on inhibitory properties. The inhibition of RR was monitored, indirectly by measuring tritiated thymidine incorporation into DNA and directly by the quantification of the EPR signal of the enzyme tyrosyl radical. 5-LO inhibition was examined spectrophotometrically, measuring the rate of linoleic hydroperoxide formation by soybean lipoxygenase. The results indicate that the substituent size introduced at the 2-position of the HPO ring is critical for determining inhibition of both enzymes. Large substituents on the 2-position, introduce a steric factor which interferes with accessibility to the iron centers. These studies have identified chelators such as 1,6-dimethyl-2-(N-4',N-propylsuccinamido)methyl-3-hydroxypyridin-4-one (CP358), which causes only a 10% inhibition of 5-LO after 24 h of incubation at 110 microm IBE (iron-binding equivalents) in comparison to simple dialkyl HPOs such as Deferiprone (CP20) which cause up to 70% inhibition. Using EPR spectroscopy, CP358 inhibits RR at a slower rate than CP20, while chelating intracellular iron(III) at a similar rate, a finding consistent with an indirect inhibition of the tyrosyl radical. However, hepatocellular iron is mobilized at a faster rate by CP358 (P < 0.001). These findings demonstrate that it is possible to design bidentate HPOs which access intracellular iron pools rapidly while inhibiting non-heme iron-containing enzymes relatively slowly, at rates comparable to DFO. It is anticipated that such compounds will possess a superior therapeutic safety margin to currently available bidentate HPOs.

Flow cytometric method for simultaneous assay of foetal haemoglobin containing red cells, reticulocytes and foetal haemoglobin containing reticulocytes.

Level of foetal haemoglobin (HbF) containing red cells (F cells) is a parameter for monitoring sickle cell anaemia (SS) patients undergoing treatment with HbF modulating drugs (including hydroxyurea (HU)). One convenient technique for F cell assay is flow cytometry. A flow cytometric method for the simultaneous assay of F cells, reticulocytes and HbF-containing reticulocytes (F reticulocytes) is described in this paper. These three parameters can be obtained within 2 h using double colour staining flow cytometry. Glutaraldehyde fixation, Triton X-100 permeabilization, monoclonal antibody to HbF Tri-colour conjugate (MoAb-HbF-TC; deep-red fluorescence) immuno-staining and thiazole orange (TO; green fluorescence) are employed. The red cell gate was set on forward scatter (FSC) and logarithmic side scatter (logSSC) for 50 000 cells on the flow cytometer. Fluorescent signals were acquired from fluorescent channel 1 (FL1; green) and (FL4; deep-red). Coefficient of variation percent (%CVs) of intra- and inter-assay were less than 9% and 15%, respectively. EDTA, citrate, heparin and CTAD anticoagulants are all suitable; the samples can be stored at 4 degrees C for up to 6 days. The method is a simple, rapid, convenient, reproducible and useful way of determining F cell, reticulocyte and F reticulocyte levels in sickle cell and thalassaemic patients.

Coronary artery bypass graft surgery in a patient with haemoglobin SC disease.

Patients with sickle cell disease who undergo surgery are generally considered to be at greater risk of peri-operative complications than otherwise healthy patients. We report a case of a woman with haemoglobin SC disease undergoing coronary artery bypass grafting. She was successfully managed with pre-operative exchange transfusion and normothermic cardiopulmonary bypass.

Deferoxamine pharmacokinetics.

Despite the clinical use of deferoxamine for more than a quarter of a century, pharmacokinetic studies are few and have not been performed explicitly in patients with sickle cell disorders. Early studies with Intravenous administration to healthy volunteers and patients with transfusional overload showed that although peak concentrations of deferoxamine were similar in both groups, concentrations of ferrioxamine were higher in the latter. In iron-overloaded patients with hereditary hemochromatosis, an intramuscular 10 mg/kg bolus of deferoxamine gave maximal plasma ferrioxamine concentrations exceeding those of deferoxamine, whereas in normal controls the reverse was the case. In more recent studies with homozygous beta-thalassemia, using continuous Intravenous deferoxamine infusion at 50 mg/kg/d, and initial elimination half-life of 0.28/h and steady-state concentration of 7 micromol/L were observed. In these studies, steady-state plasma levels of the predominant deferoxamine metabolite B were usually lower than those of unmetabolized deferoxamine. In a further intravenous infusion study, the proportion of plasma metabolites was higher in those thalassaemia patients with low serum ferritin levels relative to their current mean daily deferoxamine dose, suggesting that high metabolite levels may predict excessive desferrioxamine dosing. This hypothesis is supported by subcutaneous studies in which low doses of slow-release depot deferoxamine resulted in significantly lower proportions of plasma metabolites than with conventional 8-hour infusions at 40 mg/kg. Because serum ferritin is particularly unreliable as a marker of iron overload in sickle cell disorders, measurement of metabolites or the relative proportions of deferoxamine and ferrloxamine may help identify patients at risk of excessive dosing. Because iron overload is likely to become an increasing issue in patients with sickle cell disorders, studies of the pharmacokinetics and metabolism of deferoxamine in this patient group are needed.