HbSS Children Research Articles

Sickle cell anaemia and severe Plasmodium falciparum malaria: a secondary analysis of the Transfusion and Treatment of African Children Trial (TRACT)

SummaryBackgroundSickle cell anaemia (SCA) has historically been associated with high levels of childhood mortality in Africa. Although malaria has a major contribution to this mortality, to date, the clinical pathology of malaria among children with SCA has been poorly described. We aimed to explore the relationship between SCA and Plasmodium falciparum malaria in further detail by investigating the burden and severity of malaria infections among children recruited with severe anaemia to the TRACT trial of blood transfusion in Africa.MethodsThis study is a post-hoc secondary analysis of the TRACT trial data, conducted after trial completion. TRACT was an open-label, multicentre, factorial, randomised controlled trial enrolling children aged 2 months to 12 years who presented with severe anaemia (haemoglobin <6·0 g/dL) to four hospitals in Africa. This secondary analysis is restricted to Uganda, where the birth prevalence of SCA is approximately 1% and malaria transmission is high. Children were classified as normal (HbAA), heterozygous (HbAS), or homozygous (HbSS; SCA) for the rs334 A→T sickle mutation in HBB following batch-genotyping by PCR at the end of the trial. To avoid confounding from SCA-specific medical interventions, we considered children with an existing diagnosis of SCA (known SCA) separately from those diagnosed at the end of the trial (unknown SCA). The outcomes considered in this secondary analysis were measures of P falciparum parasite burden, features of severe malaria, and mortality at day 28 in malaria-positive children.FindingsBetween Sept 17, 2014, and May 15, 2017, 3944 children with severe anaemia were enrolled into the TRACT trial. 3483 children from Uganda were considered in this secondary analysis. Overall, 1038 (30%) of 3483 Ugandan children had SCA. 1815 (78%) of 2321 children without SCA (HbAA) tested positive for P falciparum malaria, whereas the prevalence was significantly lower in children with SCA (347 [33%] of 1038; p<0·0001). Concentrations of plasma P falciparum histidine-rich protein 2 (PfHRP2), a marker of the total burden of malaria parasites within an individual, were significantly lower in children with either known SCA (median 8 ng/mL; IQR 0–57) or unknown SCA (7 ng/mL; 0–50) than in HbAA children (346 ng/mL; 21–2121; p<0·0001). In contrast to HbAA children, few HbSS children presented with classic features of severe and complicated malaria, but both the frequency and severity of anaemia were higher in HbSS children. We found no evidence for increased mortality at day 28 in those with SCA compared with those without SCA overall (hazard ratios 1·07 [95% CI 0·31–3·76] for known SCA and 0·67 [0·15–2·90] for unknown SCA).InterpretationThe current study suggests that children with SCA are innately protected against classic severe malaria. However, it also shows that even low-level infections can precipitate severe anaemic crises that would likely prove fatal without rapid access to blood transfusion services.FundingUK Medical Research Council, Wellcome, and UK National Institute for Health and Care Research.

Revisiting Spleen Function and Pneumococcal Risk in Children with Hemoglobin SC Disease

Spleen dysfunction and susceptibility to pneumococcal infection is a well known feature in homozygous sickle cell disease (HbSS), whilst to date splenic function in hemoglobin SC disease (HbSC) has been poorly investigated. The aim of this study was to analyze spleen function in children with HbSC disease using a high-throughput validated method (1) and to examine if the current recommendations regarding pneumococcal risk are appropriate in this population.Spleen function was evaluated using a flow cytometry quantification of red blood cells (RBCs) with Howell-Jolly bodies (HJBs), in a cross-sectional study of patients at steady state during an outpatient visit in an expert center. Quantification of HJB-RBCs was performed in children with HbSC disease aged < 10 years and compared to children with HbSS disease or healthy children of the same age groups, or splenectomized children. Additional exploratory analysis was performed according to age (under or above the age of 5 years old) and treatment group (hydroxyurea).The median (Q1-Q3) HJB-RBCs count was 16 (11-28.25) /100.000 RBCs in 40 HbSC children (Figure 1). This result was not statistically different from the control group of 22 healthy children (p=0.96) nor in subgroups < or ≥ 5 years old, indicating that children with HbSC under 10 years have a preserved splenic function. Expectedly, the HJB-RBCs counts differed significantly from splenectomized children (419 (296-489)/100.000 RBCs, n=15, p<0.0001).By contrast, among the 53 HbSS children, the median HJB-RBCs count was 134 (29-216) /100.000 RBCs, differing significantly from HbSC children (p<0.0001). In HbSS children, HJB-RBCs counts increased significantly with age (r=0.30, p=0.03), showing important variability among subjects but did not reach the level found in splenectomized patients suggesting that complete loss of spleen function occurs presumably later in a majority of children in this population. Treatment with hydroxyurea did not significantly impact HJB-RBCs counts in a subgroup analysis in HbSS children.The result of this study suggests that spleen function in children under 10 years old with HbSC is not altered. The routine administration of prophylactic penicillin to young children with SC disease may therefore be questioned. Similarly, fever in children with HbSC under 3 years old may not require parenteral antibiotics as it is generally currently recommended by analogy to children with HbSS. Functional or anatomical asplenia in children with HbSC is delayed compared to those with HbSS at least after the first decade of life. Future large cohort studies using similar methodology will allow better evaluation of the pneumococcal risk in adolescents and adults with Hb SC disease.Bibliography(1) El Hoss S, Dussiot M, Renaud O, Brousse V, El Nemer W. A novel non-invasive method to measure splenic filtration function in humans. Haematologica. oct 2018;103(10):e436-9. [Display omitted] DisclosuresEl Nemer: Hemanext: Consultancy.

Biomarker Association with Hypertension in Mild Versus Severe Sickle Cell Disease Genotypes of a Single Center Cohort, in Comparison with African Americans from the Nhanes Study

Introduction: Previous studies have reported that patients with sickle cell disease (SCD) have lower systemic blood pressures when compared with age-, sex-, and race-matched controls. We compared systolic and diastolic blood pressure (SBP and DBP) measurements in an SCD patient cohort followed at our clinical center with values obtained from background population using African Americans from the National Health and Nutrition Examination Survey (NHANES) study. Furthermore, we evaluated the association of SBP and DBP with clinical and laboratory variables in our patient cohort in comparison to NHANES.Methods: We cross-sectionally analyzed 442 adult SCD patients receiving medical care at the University of Illinois at Chicago (UIC) between 2009-2018, categorized as severe (HbSS/Sβ 0-thalassemia; n=342) or mild (HbSC/Sβ +-thalassemia; n=100) genotypes. 884 African American from the NHANES were age-, sex-, and race- matched as control in a 2:1 ratio. We evaluated associations between systolic and diastolic BP and 32 clinical and laboratory variables. Evaluation of medians, interquartile range (IQR), Wilcoxon rank sum and the χ2 test, were performed on covariates. Clinical associations between biomarkers and primary outcomes of SBP, DBP, were determined by first applying single marker regression with covariates. Significant biomarkers were then analyzed by multi-marker regression and model selection to predict the relative strength of outcome association for these biomarkers. All variables included were normally distributed or transformed to normal distribution.Results: The median age of participants ranged from 31-38 years for both SCD cohorts and NHANES control. 16%, 21% and 8% of the mild genotype patients, severe genotype patients and NHANES controls, respectively were on at least one antihypertensive medication for either hypertension or proteinuria. The median (IQR) for systolic and diastolic BP for the patients with mild genotype were 122 mm Hg (112-130) and 78mmHg (70-84); severe genotype 119 mmHg (110-128) and 70 mmHg (64-75); NHANES 118(110-128) and 70 mmHg (62-78). Systolic blood pressures did not differ among the SCD groups versus NHANES, but diastolic blood pressures were higher in the mild SCD genotype patients than severe SCD patients (P<0.0001) or NHANES (P<0.0001), regardless of antihypertensive therapy. After controlling for covariates, in the severe genotype patients SBP associated significantly with gender and prior diagnosis of hypertension, but SBP associated only with hemoglobin level in the mild genotype patients. In contrast diastolic BP associated with gender and hemoglobin in the mild genotype but had no significant association in the severe genotype patients. In the NHANES controls, we observed that SBP was significantly associated with age, gender, BMI, prior hypertension, LDH, total bilirubin, urine albumin-creatinine ratio; and DBP associated with age, BMI, WBC count (Table 1).Discussion: Our SCD patient cohorts demonstrate a much higher median SBP, and for the mild genotype patients, higher DBP than was described for their age group in the cooperative study of sickle cell disease (Pegelow et al 1997). When compared with a contemporary NHANES cohort, we failed to observe a lower SBP or DBP as was expected. Higher systolic blood pressure has been reported as risk factor for the development of silent cerebral infarct in HbSS children (DeBaun et al 2014). Our study also shows that BP changes in SCD may be less influenced by traditional anthropometric measures and clinical markers. [Display omitted] DisclosuresSaraf: Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding. Gordeuk: Modus Therapeutics: Consultancy; Novartis: Research Funding; Incyte: Research Funding; Emmaus: Consultancy, Research Funding; Global Blood Therapeutics: Consultancy, Research Funding; CSL Behring: Consultancy.

Harnessing the Power of Global Health Studies for Sickle Cell Disease: Validation of a Rapid, Open-Source, Paper-Based Screening Assay in a Cohort of 1103 Tanzanian Children

Introduction: Global health research is hampered by the lack of inexpensive and reliable assays to annotate clinical study cohorts for geographically localized endemic genetic disorders. The most prevalent modifier in Africa is sickle cell disease (SCD, HbSS). In SCD, sickling of erythrocytes by polymerization of hemoglobin S (HbS) causes vaso-occlusion and hemolysis, leading to significant morbidity/mortality and constituting a major healthcare and economic burden. The inhomogeneity bias introduced into the clinical data of patient cohorts by the changes associated to undiagnosed SCD is a significant challenge. Thus, our aims were to: a) optimize a paper-based screening test for SCD for its application in suboptimal and resource-limited conditions, b) demonstrate the feasibility of retrospective SCD annotation of a large cohort of children enrolled in a global health research study, and c) extract novel evidence on potential differences in clinical presentation between febrile children with and without SCD enrolled in this cohort.Materials & Methods: First, we adapted and simplified a paper-based SCD assay (Piety et al. 2017) for suboptimal sample conditions (frozen EDTA-whole blood) and limited-resource settings. Five microlitres of thawed EDTA-whole blood was solubilized (high phosphate buffer with saponin/sodium hydrosulfite), and blotted on standard blotting paper. Dots formed by capillarity, and their aspect depended on HbS%. A high-resolution scanner and two smartphone brands were compared for image capture. An algorithm for visual calling of the presence an HbS allele was developed, and the freeware ImageJ determined peripheral/central pixel intensities. An HbS dosimetric curve was determined after identification of optimal parameter correlations by scatter plot matrix. Second, blood samples from 1103 children aged 9 to 35 months enrolled in a randomized open prospective non-inferiority pediatric cohort study on algorithm-based management of febrile illnesses in Tanzania (ePOCT Trial, 2014-6, NCT02225769, Swiss/Tanzanian IRB approval, Keitel et al.2017) were assayed with the optimized paper test. In parallel, confirmation by gold-standard alkaline Hb electrophoresis (Helena Biosciences, UK) was performed. Third, clinical data from the newly SCD-annotated ePOCT database was analyzed (STATA software suite) to identify clinical features associated with febrile illnesses in the HbAA/AS/SS groups.Results: All EDTA-blood samples frozen onsite in Tanzania (shipped and then stored for >1 year) could be assayed. The test was rapid (5'), inexpensive (0.05 USD/test) and accessible (widely available reagents, no requirement for costly equipment, open-source freeware). Determination of HbS status (homozygous HbSS/AA or heterozygous HbSA) was effective both visually and by informatic means. Smartphone cameras yielded identical results (R2=0.96 & 0.97) when compared to a high-definition scanner. Local prevalence was at 1.6% and 13.6% for HbSS and HbAS respectively, in line with previously published data. By visual sorting of blood dots, the assay was 100% sensitive and 75.8% specific for the determination of HbSS-SCD and 97.6% sensitive and 87.5% specific for the identification of an HbS allele (in an hetero- or homozygous state). After analysis of the annotated ePOCT multiparametric clinical dataset, we observed that cough as the main complaint was more prevalent in children with HbSS (OR 3.1, 95% CI: 1.1-8.3). HbSS children were more severely malnourished (MUAC/age average z-scores -0.7 vs 0.0, p=0.01) and slightly more anemic (Hb 9.1 vs 9.8 g/dL, p=0.06) when compared to HbAA counterparts. Interestingly, children with HbAS had a better nutrition status than those with HbAA (MUAC/age average z-score 0.14, p<0.01). Also, education of mothers of HbSS children was significantly lower (primary education OR 0.3 (95% CI: 0.1-0.8).Conclusions: We demonstrated that the retrospective annotation of clinical cohorts for SCD with an optimized paper-based assay is feasible, straightforward and inexpensive. Our approach has the potential to eliminate the interpretation bias associated with SCD, and thus facilitate the downstream analysis of valuable datasets in other studies. As a proof of principle, we examined a properly annotated dataset highlighting novel features of febrile illness in children with SCD and HbAS carriers in Africa. DisclosuresNo relevant conflicts of interest to declare.

Bioelectric Impedance Analysis of Body Composition of Children and Adolescents with Sickle Cell Anemia in Enugu, Nigeria

Background: Body composition indices are widely used to evaluate growth and nutrition in children, particularly those with sickle cell anemia (SCA), who are known to have impaired growth, impaired skeletal maturation, and delayed puberty. The current study is aimed at determining the body composition of children with SCA. Methods: Consecutive selection of SCA children aged 6 to 18 years, who served as subjects and their age and gender matched children with HbAA (controls), selected using multi-stage systematic sampling. It was a cross-sectional descriptive study conducted at the pediatric hematology and oncology clinic. Bioelectric impedance analysis was used to determine the body composition parameters, including weight, body fat percentage (BFP), visceral fat percentage, body mass index (BMI), skeletal muscle percentage, and resting metabolic rate. Data were analyzed using SPSS 16.0 at P < 0.05. Results: One hundred and thirty-two subjects and controls respectively were studied. Subjects had lower body composition parameters compared with controls, with the older male subjects aged 10 to 18 years, having lower body composition indices (weight, height, BMI, and BFP) compared with controls. Visceral fat percentage was low in both subjects and controls. Conclusions: Children with SCA, particularly the older males, have impaired body composition indices. There is a need to conduct further studies to determine the longitudinal aspects of growth as well as quantitative and qualitative assessment of nutritional intake in children with SCA, which will inform higher alimentation requirements for HbSS children as compared with HbAA individuals.

Acute-phase reactants, essential trace elements and some hematological parameters in Nigerian children with steady state sickle cell disorder

Background: Sickle cell disease (SCD) is an inherited chronic hematological disorder, with inflammatory responses arising from different pathways. Information is scarce about the levels of acute-phase reactants and essentials trace elements in HbSS Nigerian children. Understanding of these will further elucidate the pathophysiology of SCD, which may assist in the proper management of this condition in the pediatric population. Aim: To measure the levels of acute-phase reactants (C-reactive protein [CRP], C1q, C4, ferritin and transferrin), trace elements (Fe, Zn, Cu) and some hematological parameters in HbSS children Materials and Methods: A total number of 26 consecutive steady state HbSS children below the age of 5 years was recruited for the study. The same number of HbAA children was recruited as a control. Trace elements were determined with atomic absorption spectrophotometer. C4, C1q and CRP were quantified using immunoplates, and full blood count analysis was done according to standard hematological procedures. Results: There were no significant differences between serum mean levels of Zn, Cu, Ferritin, C4, C1q, albumin and CRP in steady state HbSS children compared to their HbAA counterparts. There was a significant increase in the level of serum iron in steady state HbSS children compared to HbAA children. There was also a significant reduction in the serum level of transferrin in steady state HbSS children compared to HbAA children. There were no significant differences between the white blood cell, red blood cell, mean corpuscular hemoglobin (Hb), mean corpuscular Hb concentration, platelets, lymphocytes, monocytes and neutrophils in steady state HbSS children compared to their HbAA counterparts. However, there was a significant reduction in the Hb concentration and hematocrit value in steady state HbSS children compared to HbAA children. Conclusion: The study observes reduced inflammation in steady state HbSS children below the age of 5 years. It is recommended that consumption of diets or use of iron containing drug by HbSS children be monitored to prevent iron overload.

Relationship between antibiotic resistance and sickle cell anemia: preliminary evidence from a pediatric carriage study in Ghana.

BackgroundAntibiotics are frequently used among people with sickle cell anemia (homozygous SS or HbSS disease), especially for prophylaxis. However, the relationship between antibiotic resistance and people with HbSS disease has not been adequately studied, especially in the developing world. The objectives of the study were (1) to compare antibiotic resistance patterns of nasal Staphylococcus aureus between children with HbSS disease and children without HbSS disease (healthy children) and (2) to evaluate nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae among children with HbSS disease.MethodsThis was a prospective cross-sectional study, and the subjects were children under 12 years old. Nasal swabs were collected from 50 children with HbSS disease and 50 children without HbSS disease. Nasopharyngeal swabs were collected from another group of 92 children with HbSS disease. The nasal and nasopharyngeal swabs were cultured for S. aureus and S. pneumoniae, respectively. Susceptibility testing was carried out on the S. aureus and S. pneumoniae isolates for various antibiotics, including penicillin, ampicillin, cefuroxime, erythromycin, cloxacillin, and cotrimoxazole.ResultsThe carriage rates of S. aureus among pediatric subjects with HbSS disease and those without HbSS disease were 48% and 50%, respectively (P > 0.05). S. pneumoniae carriage among the pediatric subjects with HbSS disease was 10%. Antibiotic resistance patterns of S. aureus carried by children with HbSS disease and children without HbSS disease were similar, and the S. aureus resistance rates were >40% for the various antibiotics, with the exception of erythromycin and cloxacillin. Low levels of S. pneumoniae resistance (0%–11%) were observed for the various antibiotics tested except cotrimoxazole, which showed an extremely high-percentage resistance (100%).ConclusionSickling status is not a risk factor for carriage of S. aureus. In this cohort of Ghanaian children with HbSS disease, S. aureus is higher in carriage and more antibiotic-resistant, compared to S. pneumoniae.

Increased IgE level in Nigerian sickle cell disease children: Implication for severity of allergic reactions

Background: Susceptibility of sickle cell disease subjects to various infectious agents is on the increase, but information relating SCD to allergic condition is scarce. Hence, assessment of immunoglobulin status in SCD children may provide useful information to improve management of SCD children. Objectives: To determine the levels of immunoglobulin classes (IgG, IgA, IgM, and IgE) in Nigerian HbSS children below 5 years of age compared with sex- and age-matched HbAA children. Materials and Methods: Blood samples were collected from a total of 45 children less than 5 years of age who were recruited into the study as follows: 26 HbSS and 19 HbAA subjects for the estimation of serum immunoglobulin levels using enzyme-linked immunosorbent assay (ELISA) techniques and determination of genotype using electrophoresis technique. Results: IgG concentration was nonsignificantly higher (P = 0.997) in HbSS children (1022.56 ± 148.97 ng/ml) compared to HbAA children (933.68 ± 106.10 ng/ml). IgA (P = 0.906) and IgM (P = 0.986) concentrations were nonsignificantly lower in HbSS children (255.07 ± 133.71 ng/ml) compared to HbAA children. IgE was significantly higher (P = 0.000***) in HbSS (108.67 ± 69.22 IU/ml) compared to HbAA (24.51 ± 17.58 IU/ml) children.Conclusion: SCD children in steady state have adequate levels of Ig classes. Non-specific elevation of IgE levels may be a factor of inflammatory response in SCD children, and this may be proposed for reduced allergic reaction among SCD children.

Study of Morphometric Collo-Diaphyseal Angle of Femur in Homozygous Sickle Cell Nigerian Children

Aims: The aim is to investigate the neck-shaft angle or Collo-Diaphyseal Angle (CDA) of femur and the effect of homozygous sickle cell (HbSS) on the angle. Study Design: A retrospective study. Place and Duration of Study: Radiology Departments of two Hospitals in Maiduguri, namely Umaru Shehu Modern Hospital and University of Maiduguri Teaching Hospital (UMTH), between January, 2009 December, 2010. Methodology: Using plain radiographs of the femur, a total of 194 HbSS and 40 control Research Article British Journal of Medicine & Medical Research, 2(4): 715-726, 2012 716 (non-HbSS) children below 17 years of age were selected. The study samples whose clinical data had been excluded from any diseases that could modify the femur were studied. The Technical Error of Measurement (TEM) was performed by the evaluator. Ethical clearance for the study was obtained from the relevant body of these government hospitals. Results: The TEM values obtained were less than 1 and were considered as a good measurement method for the evaluator performance. The CDA (mean ± standard deviations) were higher in males than females. The CDA in the left femur was greater than the right both for males and females, respectively. Furthermore, the study documents, probably for the first time that in few cases there was a reduction in the CDA of HbSS when compared with the control groups. The study revealed that there was sexually significant variation (p<0.05). The demarking points and index of sexual dimorphism of CDA show sex differences and can be used for sex determination. Conclusion: The results from this study reveal that the mean CDA of femur of HbSS children of the study population were sexually dimorphic. The information from this study may aid forensic pathologists, orthopaedic surgeons and future research in evaluation of the femur.

Soluble CD163 levels in children with sickle cell disease

Sickle cell disease (SCD) is characterized by vasculopathy, which has been causally linked to intravascular haemolysis and high levels of free plasma haemoglobin. Soluble CD163 (sCD163) is implicated in the clearance of free plasma haemoglobin and high plasma concentrations have been linked to arterial disease. We therefore investigated the value of sCD163 as a biomarker in children with SCD, and also measured haptoglobin levels in this population. We measured sCD163 in 25 control children with no haemoglobinopathy, 41 with sickle cell anaemia (HbSS) in the steady state, 27 with HbSS taking hydroxycarbamide, and 7 with HbSC disease. There was no significant difference between sCD163 levels in steady-state HbSS (1·78 mg/l) and controls (1·81 mg/l) (P = 0·86). However, sCD163 levels were significantly lower in those HbSS children taking hydroxycarbamide (1·35 mg/l) compared to both steady state HbSS (P = 0·004) and controls (P = 0·036). In children on hydroxycarbamide, sCD163 correlated negatively and highly significantly with percentage HbF (R = -0·76, P < 0·001), and this relationship was absent in those not taking hydroxycarbamide (R = 0·07, P = 0·65). sCD163 is a potentially useful biomarker in children with SCD, and may have a role in monitoring responses to hydroxycarbamide.

Coinheritance of α-Thalassemia Decreases the Risk of Cerebrovascular Disease in a Cohort of Children with Sickle Cell Anemia

The study estimated α-thalassemia (α-thal) prevalence and assessed its associations with clinical and hematological features in a random sample of Brazilian children with sickle cell anemia (208 Hb SS and 13 Hb S-β0-thal). α-Thalassemia genotyping was carried out by multiplex polymerase chain reaction (m-PCR) for seven alleles. Clinical and hematological data were retrieved from the 221 children's medical files. Their ages ranged from 2.5 to 10.4 years. Of the Hb SS children, 27.9% carried –α3.7/αα and 1.4% –α3.7/–α3.7. The presence of α-thal was significantly associated with reduction in MCV, MCH, WBC values and reticulocyte counts. No significant association with blood transfusion or acute chest syndrome (ACS), was found. α-Thalassemia genotypes were strongly associated with reduction in risk for cerebrovascular disease (CVD) (conditional and abnormal transcranial Doppler or stroke; p = 0.007). The interaction of α-thal with other modulating factors should be investigated in order to define subphenotypes of the disease and to use them as clinical tools in the follow-up care of patients.

Plasma interleukin-1β concentration is associated with stroke in sickle cell disease

The pathogenesis of sickle cell disease (HbSS), which has numerous complications including stroke, involves inflammation resulting in alteration of plasma inflammatory protein concentration. We investigated HbSS children with abnormal cerebral blood flow detected by trans-cranial Doppler ultrasound (TCD) who participated in the multi-center stroke prevention (STOP) study, to determine if plasma inflammatory protein concentration is associated with the outcome of stroke. Thirty-nine plasma samples from HbSS participants with elevated TCD who had no stroke, HbSS-NS ( n = 13) or had stroke, HbSS-S ( n = 13), HbSS steady-state controls ( n = 7) and controls with normal hemoglobin, HbAA ( n = 6), were analyzed simultaneously for 27 circulating inflammatory proteins. Logistic regression and receiver operating characteristics curve analysis of stroke on plasma inflammatory mediator concentration, adjusted for age and gender, demonstrated that interleukin-1β (IL-1β) was protective against stroke development (HbSS-NS = 19, 17–23, HbSS-S = 17, 16–19 pg/mL, median and 25th–75th percentile; odds ratio = 0.59, C.I. = 0.36–0.96) and was a good predictor of stroke (area under curve = 0.852). This result demonstrates a strong association of systemic inflammation with stroke development in HbSS via moderately increased plasma IL-1β concentration, which is furthermore associated with a decreased likelihood of stroke in HbSS.

Le syndrome drépanocytaire de type hémoglobine SC : expérience du CHU Yalgado Ouédraogo de Ouagadougou (Burkina Faso)

To evaluate the clinical features of children with hemoglobin sickle cell disease (HbSC) and compare them to children with sickle cell anemia (HbSS). This was a descriptive and retrospective study. New patients with sickle cell disease who consulted at the Yalgado Ouédraogo University Hospital's Pediatric Center in Ouagadougou, Burkina Faso, between May 2005 and June 2006, were included. They were free of any major disease unrelated to sickle cell disease. Clinical and laboratory results reported for these children were based on their health book and medical records. Sixty-one children were included in the study, 38 and 23 children were positive for HbSC and HbSS, respectively; there was no significant difference between the 2 groups in terms of sex ratio or mean age at inclusion. Mean age at diagnosis was 5 years and 2 years for HbSC and HbSS children, respectively. The first clinical event appeared at a significantly later age for HbSC than HbSS children (4 years versus 2 years). Painful episodes were equivalent in mean number per year and mean length per episode between the 2 groups; the median hemoglobin (Hb) level at inclusion was significantly higher for HbSC than for HbSS children, i.e., 95 g/l versus 70 g/l. At the Yalgado Ouédraogo University Hospital Pediatric Center, children with HbSC disease presented clinical and biological features very similar to those with HbSS.

Proinflammatory Cytokines and the Hypermetabolism of Children with Sickle Cell Disease

Sickle cell anemia (HbSS) includes chronic inflammation, but the origin is unclear. We hypothesized that in stable HbSS patients the inflammation was associated with hypermetabolism. We compared selected hypermetabolic and key immunomodulator indicators in HbSS versus control children and examined associations between measures of hypermetabolism and inflammation. Twelve fasting asymptomatic HbSS children 6-12 years and 9 controls matched for age, gender and fat mass (FM) were studied. Proportional reticulocyte count (retic%) and resting energy expenditure (REE) represented hypermetabolism, and C-reactive protein (CRP) indicated inflammation. Proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), chemokine monocyte chemoattractant protein-1 (MCP-1), and energy balance cytokine leptin were measured. Methods were indirect calorimetry, enzyme-linked immunosorbent assay, and radioimmunoassay. Statistical analysis included simple correlation and regression analysis. REE (51 +/- 6 vs. 43 +/- 12 kcal/kg per fat-free mass (FFM), mean +/- SD), retic% (12 +/- 4 vs. 0.7 +/- 0.3%), CRP (5 +/- 3 vs. 0.3 +/- 0.4 mg/liter), and IL-6 (71 +/- 40 vs. 20 +/- 7 pg/ml) were significantly higher for HbSS than controls (P < 0.05). Conversely, leptin (0.1 +/- 0.1 vs. 2 +/- 1 microg/liter per kgFM) and MCP-1 (34 +/- 5 vs. 41 +/- 4 pg/ml) were significantly lower for the HbSS subjects (P < 0.01). TNF-alpha was not significantly different. There were no significant associations between REE or retic% and any cytokine measured. However, CRP was significantly associated with REE in HbSS (r = 0.8, P = 0.003) and an important predictor of REE/FFM. We provide new evidence for low circulating levels of inflammatory chemokine MCP-1 in stable HbSS children, confirm mostly low cytokine levels, inflammation, and hypermetabolism and demonstrate association of hypermetabolism with inflammation via CRP but not via cytokines.

Quantitative Analysis of Howell-Jolly Bodies in Children with Sickle Cell Disease.

Children with sickle cell disease (SCD) have repeated vaso-occlusion within the spleen, which leads to early loss of splenic filtration function and an increased risk of sepsis from encapsulated bacteria. Functional asplenia in SCD is believed to be a gradual and cumulative process that occurs during the first few years of life, although quantitative analyses of splenic function have not been readily available. Litron has recently developed a novel high-throughput flow cytometric method of quantitating Howell-Jolly bodies (HJB, also known as micronuclei), standardized using venous blood collected in heparin and fixed within 2 hours of collection. This novel technique may be useful for understanding the normal physiological decline in splenic function that occurs in SCD. Since erythrocytes that contain HJB are normally cleared by the healthy spleen, the frequency of HJB inversely reflects splenic filtration function. To investigate the utility of this novel assay for children with SCD, a tiny aliquot (10 μL) of leftover discarded blood specimens was obtained from unselected children receiving routine clinical care in the Duke Pediatric Sickle Cell Program, fixed in ultracold methanol, stored at −80C, and then shipped to Litron for flow cytometric analysis. Erythrocytes containing HJB were identified by flow cytometry: mature CD71− erythrocytes that contain HJB are an accepted surrogate marker of splenic filtration, while HJB within the youngest CD71+ erythrocytes may reflect genotoxic damage associated with increased chromosome breaks. Initial studies determined that blood collected in EDTA was acceptable for analysis; no differences were noted with EDTA collection compared to heparin (R2=.994, n=5, p<.001). Samples fixed after 24 hours of refrigeration also showed excellent correlation with samples fixed within 2 hours (R2=.996, n-16, p<.001); blood stored for 48 hours also gave reliable results. Samples analyzed in duplicate or triplicate demonstrated high intrasample reproducibility (R2=.998, n=8, p<.001). To investigate the clinical utility of this assay, de-identified blood specimens were analyzed using EDTA-anticoagulated blood samples fixed 24-hours after collection. Children with HbSS (n=126) had increased numbers of HJB within mature CD71− erythrocytes (2504±2311 per million RBC versus 28±42 in 50 healthy controls, p<.001). The frequency of HJB was more prevalent with increased age (R2=0.30, p<.001). For HbSS children without splenectomy or hydroxyurea (HU) exposure, 89% over age 1 year, and 100% over age 3 years had >300 HJB per million RBC. Children with HbSC (n=20) had a lower frequency of HJB (131±228 per million RBC), and only 10% with >300 HJB per million RBC. Increased HJB in HbSS patients were also identified in the young CD71+ erythrocytes (0.43±0.40%, n=126, normal <0.08%). Children with HbSS and HU exposure had significantly higher numbers of HJB in CD71+ erythrocytes (0.67±0.50%, n=46) compared to children without HU exposure (0.22±0.13%, n=59, p<.001). Serial measurements in one young child on HU therapy showed decreased HJB frequency, suggesting recovery of splenic function. Quantitation of HJB by flow cytometry is a rapid, robust, and reproducible assay that will be valuable in studies of organ damage in children with SCD. Serial measurements are needed to assess preservation or recovery of splenic filtration function, as well as genotoxic damage associated with HU therapy.

Longitudinal changes in brain magnetic resonance imaging findings in children with sickle cell disease

AbstractChildren with sickle cell anemia (HbSS) are at high risk for neurologically overt cerebral infarcts associated with stroke and neurologically silent cerebral infarcts correlated with neuropsychometric deficit. We used complete magnetic resonance imaging (MRI) histories from 266 HbSS children, aged 6 through 19 years, who were enrolled in the Cooperative Study of Sickle Cell Disease (CSSCD) to examine silent infarct prevalence, localization, recurrence, and progression. We report a baseline prevalence of 21.8%, marginally higher than previously reported due to improved imaging technologies. Although we observed no overall sex difference in prevalence, most lesions in girls occurred before age 6, whereas boys remained at risk until age 10. Silent infarcts were significantly smaller and less likely to be found in the frontal or parietal cortex than were infarcts associated with stroke. Children with silent infarct had an increased incidence of new stroke (1.03/100 patient-years) and new or more extensive silent infarct (7.06/100 patient-years) relative to stroke incidence among all children in our cohort (0.54/100 patient-years). Both events were substantially less frequent than the risk of stroke recurrence among children not provided chronic transfusion therapy. Although chronic transfusion is known to decrease occurrence of new silent infarcts and strokes in children with elevated cerebral arterial blood flow velocity, further study is required to determine its risk-benefit ratio in children with silent infarct and normal velocities. Until safe and effective preventive strategies against infarct recurrence are discovered, MRI studies are best reserved for children with neurologic symptoms, neuropsychometric deficits, or elevated cerebral artery velocities.

Protein and energy metabolism in prepubertal children with sickle cell anemia.

We hypothesized that, in children with homozygous sickle cell anemia (HbSS), the shortened life-span of erythrocytes places an increased demand on protein stores, accelerates whole body protein turnover, and consequently, energy expenditure, as well as the rate of utilization of glutamine, a major fuel for reticulocytes. Eight (11.2 +/- 0.4 y old) children with HbSS who were free of infection of vaso-occlusive disease, and seven (11.3 +/- 0.4 y old) healthy black children were therefore studied in the postabsorptive state. Each received a continuous 4-h infusion of L-[1-(13)C]leucine to determine the rate of leucine oxidation, leucine rate of appearance, and nonoxidative leucine disposal, indicators of whole body protein breakdown and synthesis, respectively. Infusion of L-[2-(15)N]glutamine was used to assess rates of glutamine utilization. Resting energy expenditure and cardiac output were measured using indirect calorimetry and echocardiography, respectively. Compared with control subjects, HbSS children had a 58 and 65% higher leucine rate of appearance and nonxidative leucine disposal, respectively (both p < 0.001), 47% higher rates of whole body glutamine utilization (p < 0.01), 19% higher resting energy expenditure (p < 0.05), and 66% higher cardiac output (p < 0.01). In conclusion, children with HbSS show evidence of hypermetabolism with regard to protein, energy, and glutamine utilization. Both increased Hb synthesis and increased cardiac workload may contribute to excess protein and energy utilization. Whatever the mechanism of hypermetabolism, the data suggest that children with HbSS may have greater protein and energy requirements than the general population.

Haemoglobin F and A2in Nigerian Children with Sickle Cell Anaemia

The concentration of haemoglobins F and A2 in 132 Hb SS children aged 6 months to 16 years and 50 age- and sex-matched controls has been determined. The mean HbF concentration in Hb SS patients and controls were 9.5 per cent (range 1.7-24.5 per cent) and 1.5 per cent (range 0.5-14.4 per cent) respectively while HbA2 concentrations were 2.7 per cent (range 1.6-3.7 per cent) and 2.4 per cent (range 1.3-3.9 per cent) respectively. For 18 Hb SS patients seen in the stable state and during vaso-occlusive crisis, there was no significant difference in HbF concentration between the two states.

Cerebral Vessel Stenosis in Sickle Cell Disease

Ischemic stroke is a common and disabling complication of sickle cell disease (Hb SS). Most infarctions occur in the presence of intracranial stenotic lesions of the large vessels of the circle of Willis. Transcranial Doppler (TCD), by measuring flow velocity in these arterial segments, can detect focal stenosis on the basis of elevated flow velocity. We report the preliminary results of a prospective study to develop criteria for detection of stenotic lesions based on TCD and identification of patients with Hb SS at risk for stroke. Comparing the TCD findings from six patients with lesions demonstrated by angiography to those from 115 Hb SS children without stroke, we conclude: (a) middle cerebral (MCA), anterior cerebral (ACA), or internal carotid (ICA) artery mean velocities greater than 190 cm/s strongly suggest focal stenosis; (b) MCA or ACA mean velocities of 150 to 190 cm/s suggest abnormality but at present cannot be considered diagnostic of stenosis; (c) mean velocities up to 150 cm/s are possibly due to the effects of low hematocrit and/or young age, and cannot as yet be distinguished from velocity elevations due to vessel stenosis.

Increased incidence of hepatitis B markers in children with sickle-cell anemia.

Screening of 143 children 6 months to 12 years of age with sickle-cell anemia showed that 39.2% were HBsAg-positive as compared with 19.3% of the 161 control children of the same age group, who had Hb genotype AA (chi 2 = 14.7383; P less than 0.001). Fifty percent of the HbSS children under the age of 1 year were HBsAg-positive as opposed to 4.3% of the control group (chi 2 = 9.1955; P less than 0.001), while 28.6% of patients were HBsAg-positive at the age of 4 years compared with only 7.4% of the controls at the same age. The incidence of anti-HBc in both groups was similar. Markers of HBV infection (HBsAg + anti-HBc) were, however, on the whole higher in the patients with sickle-cell anemia [88/118 (74.6%)] than in the controls [54/88 (61.3%; P less than 0.005)].