Red Cell Consumption Research Articles

PB2403 ROLE OF HYDROXYUREA IN BETA THALASSEMIA INTERMEDIA

Background:Thalassemia Intermedia is a term used to define a group of patients with β thalassemia in whom the clinical severity of the disease is somewhere between the mild symptoms of the β thalassemia trait and the severe manifestations of β thalassemia major.1,2Thalassemia intermedia encompasses a wide clinical spectrum. Mildly affected patients are completely asymptomatic until adult life, experiencing only mild anemia and maintaining hemoglobin levels between 7‐10g/dL. These patients require only occasional blood transfusions, during acute infections or blood loss. Patients with more severe thalassemia intermedia generally present between the ages of 2 to 6 years, and although they are able to survive without regular transfusion therapy, but growth and development can be retarded.2There is currently no definitive treatment to correct the globin chain imbalance in thalassemia, but the promising approach involves the use of therapeutic agents to definitively correct the globin chain imbalance by re‐activating the fetal globin genes. Hydroxyurea, a cytotoxic drug,is reported to be useful in reducing this degree of imbalance, thus decreasing the disease severity. Due to the lesser α/β globin imbalance in β‐thalassemia intermedia (TI), compared with thalassaemiamajor, better clinical responses are expected in patients with TI. 3,4 Aims:Objective: To determine the clinical response and frequency of side effects of hydroxyurea in thalassemia intermedia patients in local population.Methods:Patients and methods: Descriptive case series study was conducted in Pediatrics Department of Fatima Memorial Hospital, Lahore from August to December 2016. Total 150 patients clinically diagnosed to have thalassemia intermedia fulfilling inclusion criteria were enrolled, interviewed and examined. Baseline investigations were sent to monitor the side effects of hydroxyurea. Hydroxyurea was started at dose of 15 mg/kg/day and patients were called after every fortnight for first 8 weeks and then monthly for 4 months.If no response seen on first visit, dose was increasedto 20 mg/kg/day and called again after 2 weeks. If still no rise in Hb observed, labelled as” no response”, if Hb increase then label as according to clinical response criteria. Patients were graded according to clinical response criteria after 3 months starting of hydroxyurea. For blood transfusion frequency, patients’ blood transfusion record was explored for their mean pre‐transfusionHb levels and red cell consumption after and before start of hydroxyurea in 3 months. For leucopenia, complete blood count was repeated after 1 month starting hydroxyurea.For diarrhea, clinical examination and assessment was done after 1 month of starting hydroxyurea. For neuropathy clinical assessment was done periodically first on monthly visits.Results:Out of 150 patients, 79(53%) were transfusion dependent and 71 (47%)were transfusion independent. Total of 123 (82%) showed response and 27 (18%) showed no response even after increasing dose from 15 mg/kg/day to 20 mg/kg/day. Out of 123 responders, 74 (49.3%) were good responder, 49 (32.7%) were partial responder. In good responders mean increment in hemoglobin ranged between 1.5 g/dl to 2.5 g/dl.Summary/Conclusion:Conclusion: Hydroxyurea is an effective and well tolerated drug for the treatment of thalassemia intermedia with very few side effects. With use of this medicine, regular blood transfusions and its hazards can be prevented in these patients.

Impact of genotype on endocrinal complications in β-thalassemia patients.

In β-thalassemia, certain mutations cause a complete absence of β-globin chain synthesis, termed β0-thalassemia, while others may allow certain β-globin production and are termed β+- or β++-thalassemia. The homozygous state results in severe anemia, which requires regular blood transfusion. By contrast, frequent blood transfusion can in turn lead to iron overload, which may result in several endocrinal complications. The present study aimed to investigate the impact of genotype on the development of endocrine complications in β-thalassemia patients. A cross-sectional study was conducted on 100 thalassemia patients >10 years. A data abstraction form was designed to capture the appropriate information from the individual medical records, including full clinical, laboratory, transfusion and chelation data. The genotype of the patients was identified by the DNA sequencing technique. Growth retardation and hypogonadism were the most prominent endocrinal complications (70 and 67%, respectively) followed by hypothyroidism, diabetes mellitus and hypoparathyrodism (8, 8 and 7%, respectively). The most common mutations identified were IVS-1-110, IVS-1-1 and IVS-1-6 (63, 47 and 41%, respectively). Patients with the β0β0 genotype had a significantly higher prevalence of growth retardation, hypogonadism, hypothyroidism and hypoparathyrodism compared to those with the β0β+ and β+β+ genotypes (P<0.001, P<0.001, P<0.001 and P=0.037, respectively). Patients with the homozygous IVS-11-745 mutation had a significantly higher prevalence of diabetes (P=0.001). The underlying genetic defect in thalassemia patients is a contributing factor for the development of endocrinal complications, as patients with the more severe defects have a greater rate of iron loading through higher red cell consumption.

The relationship between myocardial t2* and left ventricular volumetric and functional parameters in thalassemia major patients

Cardiac involvement in thalassemia major (TM) is mainly characterized by left ventricular dysfunction caused by iron overload. Cardiovascular magnetic resonance imaging (MRI) including myocardial T2* measurement is becoming increasingly popular for quantitatively evaluating myocardial iron overload. The aim of this study was to evaluate the relationship between the myocardial T2* value and left ventricular functional parameters and to examine the associations between the degree of cardiac iron load and various clinical parameters. A retrospective analysis of 47 patients (25 males and 22 females; mean age, 23.0±5.4 years) with TM was performed. Myocardial iron load was assessed by T2* measurements, and volumetric functions were analyzed using the steady state free precession sequence. RESULTS In patients with myocardial iron deposition (T2* < 20 ms), the mean left ventricular ejection fraction (LVEF) was 64.73±4.94%. The LVEF of patients with myocardial siderosis was significantly lower than that of patients without myocardial siderosis (r=0.35, P = 0.014). Inverse and significant correlations between both the left ventricular (LV) end-systolic volume index and the LV end-diastolic volume index and the myocardial T2* value (r=-0.32, P = 0.027 and r=-0.29, P = 0.046, respectively) were observed. There was an inverse correlation between the myocardial T2* value and the liver iron concentration (r=-0.31, P = 0.037). Cardiac T2* was not associated with serum ferritin levels, pre-transfusion hemoglobin levels or the annual red cell consumption rate. Myocardial iron load assessed by cardiac MRI (T2*) is associated with deterioration in left ventricular function. Thalassemia major patients with myocardial siderosis may have LVEF values within normal limits, but this result must be interpreted cautiously.

The impact of genotype on endocrine complications in thalassaemia major

The clinical severity in thalassaemia major (TM) depends on the underlying mutations of the beta-globin gene and the degree of iron overload. The aim of the study was to investigate the impact of genotype on the development of endocrine complications in TM in our center. 126 (62 males, 64 females) thalassaemic patients of Greek Cypriot origin with a mean age of 31.2 (17-68) yr were included in the study. All patients, who were on the standard treatment protocol, were subsequently divided into two groups according to their genotype, group A (92): TM with no mitigating factor and group B (34): TM carrying one or more mitigating factors in the beta- and/or alpha-globin genes. Iron overload calculation was based on the amount of red cell consumption and the mean ferritin level over a 12-year period. Statistical analysis was performed with the SPSS program. Patients in group A, who were consuming larger amounts of blood on transfusions, were more likely to develop hypogonadism (P = 0.001) compared with patients in group B, despite their similar mean ferritin levels. The incidence of other endocrinopathies (short stature, hypothyroidism, and diabetes mellitus) was similar in the two groups. The prevalence of hypothyroidism in splenectomized patients was significantly higher (P = 0.005), whereas the presence of hypogonadism, impaired glucose homeostasis and insulin resistance, although more frequent, was not statistically significant. The clinical severity of TM had no impact on bone mineral density (BMD) in both men and women. BMD was only influenced by gonadal function. This study demonstrates that the underlying genetic defect in TM is a contributing factor for gonadal dysfunction, because the patients with the more severe defects have a greater rate of iron loading through higher red cell consumption.

EXTRA-CORPOREAL PERFUSION OF NORMAL AND hDAF TRANSGENIC LIVERS WITH HUMAN BLOOD

212 The development of pigs transgenic for human decay accelerating factor (hDAF) has led to a resurgence of interest in extra-corporeal liver perfusion in the treatment of acute liver failure. We have developed an isolated perfusion system which incorporates oxygenation, temperature regulation and independent perfusion of the artery and portal vein. When pig livers were perfused with pig blood (n=5), reliable synthetic function and metabolic function were maintained for at least 3 days, at which stage essentially normal histological appearances were seen. Synthetic function was demonstrated by CH50 analysis (complement levels increased four-fold), urea production (increased 15 fold with unchanged creatinine levels) and factor V synthesis (stable factor V levels, whereas anhepatic perfusions showed no factor V activity after 36 hours). Metabolic function was demonstrated by acid base and potassium maintenance within the normal physiologic range. When connected to an anaesthetised pig in acute liver failure, stabilisation of metabolic (pH) and cardiovascular (arterial pressure, peripheral vascular resistance, inotrope requirement) parameters were maintained for the duration of perfusion. Unsupported control animals died with a mean survival of 17 hours (n=5). When normal (n=5) and hDAF transgenic (n=5) pig livers were perfused with fresh human blood, synthetic and metabolic function was demonstrated in both groups. Transgenic livers produced significantly more complement and urea (p<0.01) while factor V production was similar. Factor V levels stabilised at porcine rather than at human levels (400% vs. 100%). Metabolic function was significantly better (p <0.01) in transgenic livers than in nontransgenic livers as assessed by acid-base and potassium homeostasis. There was no evidence of hyperacute rejection. However, in both groups of xenoperfusions the duration of function was limited by progressive loss of red cells. The red cell loss appears to be of immunological origin and due to phagocytosis rather than haemolysis. The rate of red cell consumption, however, is compatible with a modest transfusion requirement and may not, therefore, restrict clinical application.

４種類の赤血球保存液の比較試験 ７施設での検討結果

Four red cell additive solutions, in which 3 are licenced in the U. S. A. and the last is an experimental additive were evaluated in 7 Blood Centers with the same experimental protocol. The ACD-A-anticoagulated red cells were suspended with one of additives (ADSOL, Baxter; SAGM, Terumo; OPTISOL, Terumo; MAP developed by Dr. S. Sasagawa of Japanese Red Cross) with a hematocrit of 55-65%. Then they were stored in PVC plastic blood bags for 49 days at 4°C. The ATP, 2, 3-DPG levels, morphologic scores, and glucose consumption of red cells were similar in 4 additives. The degree of %hemolysis was the least in MAP. But, the pH levels of RC suspended with MAP were lower by 0.1 unit than those of remaining 3 additives. The resistance to low osmolarity was slightly better in MAP than those of 3 remaining additives. The overall results suggest that MAP and OPTISOL caused a slightly better results in preventing hemolysis, although the data from another parameters indicate that there were no significant differences between 4 additives. Therefore, we should introduce MAP or OPTISOL into the Japanese Blood Program because of the low levels of hemolysis.

Oxygen affinity of avian blood

Oxygen dissociation curves plotted directly on whole blood during oxygénation using a Radiometer DCA 1 gave P 50 values of 39.2 ± 2.2 mm Hg and 51.3 ± 6.2 mm Hg for pigeon and chicken blood, respectively, at 41 °C, pH 7.5 and P CO 2 29 mm Hg. These values agree well with earlier results obtained by a variety of methods; however, they do conflict with recent findings of a much higher oxygen affinity in avian blood which were obtained using a different plotting method. It was shown that with the method used in this paper the high metabolic rate of avian blood has little effect on the plotted curve at saturations below 50%. At higher saturations O 2 consumption of red cells affects a progressive shift of the curve to the left so that to obtain accurate curves at high saturation it is necessary to correct the plotted curves for the oxygen utilization.

Effects of bilirubin on red cell metabolism.

Blirubin causes certain defects in erythrocyte metabolism, mainly in glycolysis. These effects of bilirubin were studied in vitro using a relatively physiological assay medium, which consisted of heparinized whole blood. Bilirubin was added in a small quantity of NaOH solution. In the presence of bilirubin a reduced glucose consumption of red cells and an accelerated depletion in the ATP and glycerate-2,3-bisphosphate concentration was found. Bilirubin levels lower than 50 mumol/l did not influence the glucose consumption. In agreement to other investigations it was established that bilirubin causes haemolysis of red cells. ATP-deficient cells are more sensitive to this effect.