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- Calcium in Red Blood Cells-A Perilous Balance. [JOURNAL ARTICLE]
- Int J Mol Sci 2013; 14(5):9848-9872.
Ca2+ is a universal signalling molecule involved in regulating cell cycle and fate, metabolism and structural integrity, motility and volume. Like other cells, red blood cells (RBCs) rely on Ca2+ dependent signalling during differentiation from precursor cells. Intracellular Ca2+ levels in the circulating human RBCs take part not only in controlling biophysical properties such as membrane composition, volume and rheological properties, but also physiological parameters such as metabolic activity, redox state and cell clearance. Extremely low basal permeability of the human RBC membrane to Ca2+ and a powerful Ca2+ pump maintains intracellular free Ca2+ levels between 30 and 60 nM, whereas blood plasma Ca2+ is approximately 1.8 mM. Thus, activation of Ca2+ uptake has an impressive impact on multiple processes in the cells rendering Ca2+ a master regulator in RBCs. Malfunction of Ca2+ transporters in human RBCs leads to excessive accumulation of Ca2+ within the cells. This is associated with a number of pathological states including sickle cell disease, thalassemia, phosphofructokinase deficiency and other forms of hereditary anaemia. Continuous progress in unravelling the molecular nature of Ca2+ transport pathways allows harnessing Ca2+ uptake, avoiding premature RBC clearance and thrombotic complications. This review summarizes our current knowledge of Ca2+ signalling in RBCs emphasizing the importance of this inorganic cation in RBC function and survival.
- Hemoglobinopathies: Slicing the Gordian Knot of Plasmodium falciparum Malaria Pathogenesis. [Journal Article]
- PLoS Pathog 2013 May; 9(5):e1003327.
Plasmodium falciparum malaria kills over 500,000 children every year and has been a scourge of humans for millennia. Owing to the co-evolution of humans and P. falciparum parasites, the human genome is imprinted with polymorphisms that not only confer innate resistance to falciparum malaria, but also cause hemoglobinopathies. These genetic traits-including hemoglobin S (HbS), hemoglobin C (HbC), and α-thalassemia-are the most common monogenic human disorders and can confer remarkable degrees of protection from severe, life-threatening falciparum malaria in African children: the risk is reduced 70% by homozygous HbC and 90% by heterozygous HbS (sickle-cell trait). Importantly, this protection is principally present for severe disease and largely absent for P. falciparum infection, suggesting that these hemoglobinopathies specifically neutralize the parasite's in vivo mechanisms of pathogenesis. These hemoglobin variants thus represent a "natural experiment" to identify the cellular and molecular mechanisms by which P. falciparum produces clinical morbidity, which remain partially obscured due to the complexity of interactions between this parasite and its human host. Multiple lines of evidence support a restriction of parasite growth by various hemoglobinopathies, and recent data suggest this phenomenon may result from host microRNA interference with parasite metabolism. Multiple hemoglobinopathies mitigate the pathogenic potential of parasites by interfering with the export of P. falciparum erythrocyte membrane protein 1 (PfEMP1) to the surface of the host red blood cell. Few studies have investigated their effects upon the activation of the innate and adaptive immune systems, although recent murine studies suggest a role for heme oxygenase-1 in protection. Ultimately, the identification of mechanisms of protection and pathogenesis can inform future therapeutics and preventive measures. Hemoglobinopathies slice the "Gordian knot" of host and parasite interactions to confer malaria protection, and offer a translational model to identify the most critical mechanisms of P. falciparum pathogenesis.
- Outcome of patients with hemoglobinopathies given either cord blood or bone marrow transplantation from an HLA-identical sibling. [JOURNAL ARTICLE]
- Blood 2013 May 21.
We analyzed the outcomes of 485 patients with thalassemia major (TM) or sickle cell disease (SCD) receiving HLA-identical sibling cord blood transplantation (CBT, n=96) or bone marrow transplantation (BMT, n=389). Compared to patients given BMT, CBT recipients were significantly younger (median age 6 versus 8 years, p=0.02), and were treated more recently (median year 2001 versus 1999, p<0.01). A higher proportion of patients with TM belonging to classes II-III of the Pesaro classification received BMT (44%) compared to CBT (39%, p<0.01). In comparison with patients receiving BMT (n=259, TM; n=130, SCD), those given CBT (n=66, TM; n=30, SCD) had slower neutrophil recovery, less acute graft-versus-host disease (GVHD) and none had extensive chronic GVHD. With a median follow-up of 70 months, the 6-year overall survival was 95% and 97% after BMT and CBT, respectively (p=0.92). The 6-year disease-free survival (DFS) was 86% and 80% in TM patients after BMT and CBT, respectively, while DFS in SCD patients was 92% and 90%, respectively. The cell dose infused did not influence outcome of patients given CBT. In multivariate analysis, DFS did not differ between CBT and BMT recipients. Patients with TM or SCD have excellent outcomes after both HLA-identical sibling CBT and BMT.
- Oral Ketamine for Sickle Cell Crisis Pain Refractory to Opioids. [JOURNAL ARTICLE]
- J Pain Palliat Care Pharmacother 2013 May 21.
ABSTRACTThere is literature demonstrating that the N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has analgesic properties that can be used as an adjuvant to opiates for pain relief in multiple various conditions and pain states. However, there is a lack of published information on ketamine used in persons with sickle cell disease in acute pain crises. The Virginia Commonwealth University Palliative Care team was consulted on a 38-year-old African American female with sickle cell thalassemia in severe acute pain crisis overlying chronic pain related to her disease. Pain control was unable to be achieved with escalating doses of opiates and other adjuvant medications. The patient responded well to an intravenous test dose of ketamine and was subsequently placed on an oral regimen of ketamine in addition to opiates. In the 24-hour period following ketamine initiation, the patient's pain was able to be controlled on decreased amounts of opiates. She was eventually transitioned to an oral opiate and ketamine regimen, which allowed her to be discharged home with pain levels close to her baseline and the ability to function and perform all activities of daily living.
- Chorionic villous sampling: experience of 636 cases. [Journal Article, Research Support, Non-U.S. Gov't]
- J Med Assoc Thai 2013 Apr; 96(4):383-8.
To describe the technical aspects and complications of chorionic villous sampling (CVS).The database of CVS procedures performed between January 2004 and August 2011 at Maharaj Nakorn Chiang Mai Hospital was assessed prospectively. Consecutive procedures during 10 to 14 gestational weeks were included into the present study. Indications, results, and complications of the CVS were extracted and analyzed.All 636 CVS procedures were successful. Indications for CVS were fetal karyotyping, DNA analysis for severe thalassemia disease, and for both in 36.5%, 50. 6%, and 12.9%, respectively However, 3.4% had inconclusive CVS result, and the second trimester prenatal diagnosis procedures needed to be done. There were five cases (0.8%) of fetal loss in the present study. Only two cases (0.3%) that fetal loss happened within two weeks of CVS procedures. Other minor complications such as vaginal bleeding and amniotic fluid leakage were found in 0.3 to 1.3% and had no long-term effect. No case with anomaly and procedure-related infection following the procedure was seen.CVS is a safe and reliable prenatal diagnosis procedure in the first trimester. In experienced operators, fetal loss rate was less than 1%. However a few cases will have inconclusive CVS results and may need a confirmation during the second trimester diagnostic procedures.
- Hematological and Genetic Predictors of Daytime Hemoglobin Saturation in Tanzanian Children with and without Sickle Cell Anemia. [Journal Article]
- ISRN Hematol 2013.:472909.
Low hemoglobin oxygen saturation (SpO2) is common in Sickle Cell Anemia (SCA) and associated with complications including stroke, although determinants remain unknown. We investigated potential hematological, genetic, and nutritional predictors of daytime SpO2 in Tanzanian children with SCA and compared them with non-SCA controls. Steady-state resting pulse oximetry, full blood count, transferrin saturation, and clinical chemistry were measured. Median daytime SpO2 was 97% (IQ range 94-99%) in SCA (N = 458), lower (P < 0.0001) than non-SCA (median 99%, IQ range 98-100%; N = 394). Within SCA, associations with SpO2 were observed for hematological variables, transferrin saturation, body-mass-index z-score, hemoglobin F (HbF%), genotypes, and hemolytic markers; mean cell hemoglobin (MCH) explained most variability (P < 0.001, Adj r (2) = 0.09). In non-SCA only age correlated with SpO2. α-thalassemia 3.7 deletion highly correlated with decreased MCH (Pearson correlation coefficient -0.60, P < 0.0001). In multivariable models, lower SpO2 correlated with higher MCH (β-coefficient -0.32, P < 0.001) or with decreased copies of α-thalassemia 3.7 deletion (β-coefficient 1.1, P < 0.001), and independently in both models with lower HbF% (β-coefficient 0.15, P < 0.001) and Glucose-6-Phosphate Dehydrogenase genotype (β-coefficient -1.12, P = 0.012). This study provides evidence to support the hypothesis that effects on red cell rheology are important in determining SpO2 in children with SCA. Potential mechanisms and implications are discussed.
- Weak d types in the egyptian population. [Journal Article]
- Am J Clin Pathol 2013 Jun; 139(6):806-11.
Patients with the most common weak D types 1, 2, and 3 can be safely considered D positive. We evaluated 1,113 Rh-negative Egyptian samples for weak D expression to propose a cost-effective strategy related to D variant testing. D variants were tested using polymerase chain reaction with sequence-specific priming. Fifty samples were D variants (4.5%): weak D type 4.2 (32%), weak D type 4.0/4.1 (16%), and weak D type 15 (2%). Fifteen (62.5%) of 24 samples were identified serologically as partial D. We also studied the probability of the development of anti-D in 52 Rh-negative children with thalassemia who were receiving units for which weak D was not tested. Anti-D alloimmunization was observed in 63.5% of patients with thalassemia. It is prudent to implement weak D typing in Egyptian donors. Weak D variants of Egyptians are significantly different compared with Caucasians. Ethnicity must be taken into consideration when developing clinical and prenatal strategies related to D variants.
- Distribution of thalassemias and associated hemoglobinopathies identified by prenatal diagnosis in Taiwan. [JOURNAL ARTICLE]
- Blood Cells Mol Dis 2013 May 17.
BACKGROUND:Hemoglobin (Hb) gene disorders are common hereditary disorders in Taiwan, and α- and β-thalassemias are among the well-known Hb disorders here. Our study provides a primary reference for designing a locally relevant antenatal diagnostic test to control the spread of thalassemia.
METHODS:Between 1998 and 2011, prenatal diagnoses for identifying thalassemia and hemoglobinopathies were performed on 1240 fetuses at risk for α-hydrops and β-thalassemia major.
RESULTS:Of 1240 specimens analyzed, 1082 (87%) were obtained by amniocentesis; 125 (10%), by chorionic villus sampling; and 33 (3%), by cordocentesis. Prenatal diagnoses revealed that 21.5% of these fetuses as thalassemia major (including α-thalassemia hydrops, β-thalassemia major, and Hb E/β-thalassemia); 50.2%, for thalassemia minor (include α-thalassemia carrier, β-thalassemia carrier, and α-thalassemia combined β-thalassemia carrier); and 28.3% for normal type (include non-α, β-thalassemia). The most common α-hydrops were SEA (Southeast Asian) and Philippine type (frequencies of 74.91 and 5.24%, respectively). The frequency of the IVS-II-654 combined codons 41/42 mutation, the most common β-thalassemia major mutation in this region, was 5.24%. Two fetuses were found with E/β-thalassemia (HbE/IVS-II-654 and HbE/codons 41/42, respectively). Since 1993, Taiwan's Department of Health adopted a national program for screening pregnancies to control spread of thalassemia. In the last 10years, less than 3 such cases have occurred per year. After 2003, this number was 0 for a total of 4years (2003, 2004, 2007, and 2008).
CONCLUSION:In Taiwan, incidence and frequency of thalassemia genotypes were similar to those previously reported. The national program for screening pregnancies to control spread of thalassemia that resulted in a marked decline in the number of newborns with thalassemia major. Interestingly, prenatal diagnoses revealed 21.5% for thalassemia major, 50.2% for thalassemia minor, 28.3% normal comparison of thalassemia type distribution showed normal type increasing by 13.2% and major type decreasing by 14%. This unique and significant finding needs further clinical studies and discussion to explain such a phenomenon.
- Treatment of heart failure in adults with thalassemia major: response in patients randomised to deferoxamine with or without deferiprone. [JOURNAL ARTICLE]
- J Cardiovasc Magn Reson 2013 May 20; 15(1):38.
BACKGROUND:Established heart failure in thalassaemia major has a poor prognosis and optimal management remains unclear.
METHODS:A 1 year prospective study comparing deferoxamine (DFO) monotherapy or when combined with deferiprone (DFP) for patients with left ventricular ejection fraction (LVEF) <56% was conducted by the Thalassemia Clinical Research Network (TCRN). All patients received DFO at 50--60 mg/kg 12--24 hr/day sc or iv 7 times weekly, combined with either DFP 75 at mg/kg/day (combination arm) or placebo (DFO monotherapy arm). The primary endpoint was the change in LVEF by CMR.
RESULTS:Improvement in LVEF was significant in both study arms at 6 and 12 months (p = 0.04), normalizing ventricular function in 9/16 evaluable patients. With combination therapy, the LVEF increased from 49.9% to 55.2% (+5.3% p = 0.04; n = 10) at 6 months and to 58.3% at 12 months (+8.4% p = 0.04; n = 7). With DFO monotherapy, the LVEF increased from 52.8% to 55.7% (+2.9% p = 0.04; n = 6) at 6 months and to 56.9% at 12 months (+4.1% p = 0.04; n = 4). The LVEF trend did not reach statistical difference between study arms (p = 0.89). In 2 patients on DFO monotherapy during the study and in 1 patient on combined therapy during follow up, heart failure deteriorated fatally. The study was originally powered for 86 participants to determine a 5% difference in LVEF improvement between treatments. The study was prematurely terminated due to slow recruitment and with the achieved sample size of 20 patients there was 80% power to detect an 8.6% difference in EF, which was not demonstrated. Myocardial T2* improved in both arms (combination +1.9 +/- 1.6 ms p = 0.04; and DFO monotherapy +1.9 +/- 1.4 ms p = 0.04), but with no significant difference between treatments (p = 0.65). Liver iron (p = 0.03) and ferritin (p < 0.001) both decreased significantly in only the combination group.
CONCLUSIONS:Both treatments significantly improved LVEF and myocardial T2*. Although this is the largest and only randomized study in patients with LV decompensation, further prospective evaluation is needed to identify optimal chelation management in these high-risk patients.
- Effect of zinc supplementation on serum antibody titers to heat shock protein 27 in patients with thalassemia major. [JOURNAL ARTICLE]
- Hematology 2013 May 16.