HbAA Group Research Articles

Clinical Profile and middle cerebral artery velocity of children with sickle cell anaemia seen in UUTH, Uyo, Akwa Ibom state, Nigeria.

The risk of stroke in individuals with Sickle Cell Anaemia (SCA) can be assessed by routine non-invasive measurement of their cerebral blood flow using a Transcranial Doppler (TCD) ultrasound scan. This study aimed to determine the difference in blood flow velocity parameters in the middle cerebral artery (MCA) of children with sickle cell anaemia compared to a normal age-matched population. This was a hospital-based comparative cross-sectional study among 40 SCA patients aged 3-16 years, in steady state and 40 age and sex-matched HbAA healthy subjects. This study lasted from June to October 2019. Medical history was retrieved using a structured questionnaire. The time-averaged mean of maximum velocity (TAMMV) of the right and left MCA was measured using non-imaging TCD. The mean age ± SD of the SCA patients was 9.1 ± 4.4 years. The SCA patients and sex and age-matched HbAA group consisted of 23 (57.5%) males and 17 (42.5%) females respectively. SCA patients had a significantly lower mean ± SD haemoglobin (Hb) than the controls (7.1 ± 1.1g/dl vs 11.1 ± 1.4g/dl; p<0.001). The right MCA of the patients with SCA had a significantly higher mean flow velocity compared to the controls (94.1 ± 23.1 vs 55.0 ± 8.8cm/sec, p<0.001). The mean TAMMV recorded in the SCA subjects were significantly higher than that of the non-SCA subjects. There is a need to ensure that TCD ultrasound is employed as a routine screening tool for stroke risk among SCA patients in Nigerian tertiary health institutions.

Povišena srednja zapremina eritrocita u anemiji srpastih ćelija - jedna priča, previše?

Abstract: Introduction: Sickle cell disease is a hereditary blood disorder characterized by defective hemoglobin. Red cell indices are proposed as potential tools for diagnosing and managing sickle cell disorders. Materials and Methods: This study aimed to assess the utility of red cell indices as screening tools for sickle cell anemia. One hundred consenting adults of both sexes participated. Haematological parameters, including packed cell volume, hemoglobin values, hemoglobin electrphoretic patterns, and red blood cell count, were examined. Mean cell volume (MCV), mean cell hemoglobin concentration (MCHC), and mean cell hemoglobin (MCH) were calculated. Data analysis was performed using GraphPad Prism Software Version 9, with statistical significance set at p &lt; 0.05 (95% confidence interval). Results: Haemoglobin values were significantly lower in Hb SS subjects (5.68 ± 1.7g/dl) compared to Hb AA (11.30 ± 1.5 g/dl) and Hb AS groups (11.03 ± 1.4 g/dl) (F = 32.279; p &lt; 0.00001). The pattern was consistent with PCV and RBC values. Among the red blood cell indices assessed, only MCV showed a significant elevation (95.7 ± 2.4 fl) in the HbSS group compared to other groups (F = 4.165; p = 0.0183). No statistically significant difference was observed in MCHC and MCH values between the three groups (F = 0.5373, p &gt; 0.586 for MCHC; F = 0.607, p &gt; 0.546 for MCH). The prevalence of haemoglobin variants was as follows: HbAA (77%), HbAS (19%), and HbSS (4%). Conclusion: This study highlights significant reductions in haemoglobin values in Hb SS subjects and a notable elevation in MCV values in the Hb SS blood group. Elevated MCV in sickle cell anemia, where red cells are typically microcytic, warrants further investigation for differential diagnosis.

Donor Hemoglobin Genotype Does Not Impact Outcomes Following Matched Related Donor Hematopoietic Cell Transplantation for Sickle Cell Disease: A STAR Study

Sickle cell disease (SCD) is an inherited hemoglobin (Hb) disorder which leads to significant morbidity and early mortality. Hematopoietic cell transplantation (HCT) is the only curative treatment with long-term outcome data, demonstrating excellent symptom-free survival particularly when a matched related donor (MRD) is available. Most MRD have sickle cell trait (Hb AS), but trait donor HCT is considered acceptable by the FDA and without negative impact. Further, initial gene addition and editing approaches for SCD have resulted in a trait-like status with benefit. Sickle trait, however, is associated with complications such as papillary necrosis, bacteriuria, splenic infarction, and exercise-induced death. The primary aim of this study was to compare long-term outcomes following MRD HCT for SCD based on donor Hb genotype, to objectively describe any impact on outcomes. Retrospective data was available for this analysis on 182 SCD patients ≥1 year post MRD HCT at 10 participating Sickle Transplant Advocacy and Research (STAR) Alliance centers. Summary statistics were presented as mean (standard deviation) for continuous variables and count (%) for categorical variables. Comparisons were made between Hb AA and Hb AS donor groups using both parametric and non-parametric tests for continuous variables and Chi-square test/exact test for categorical variables, with p-value &amp;lt;0.05 set as significant. Amongst 182 patients undergoing MRD HCT, 67% (n=122) had a Hb AS donor ( Table). In the overall cohort, median age at HCT was 8.7 (4.8) years and most patients had HbSS (n=174; 96%) with a severe clinical phenotype (n=97; 54%). HCT was performed using bone marrow (n=166; 92%) with myeloablative conditioning (n=156; 86%) in the majority. Patients with a severe disease phenotype and Hb AS donor were significantly more likely to have recurrent vaso-occlusive pain crises as an indication for HCT (p=0.033), otherwise there were no differences in baseline patient or HCT characteristics between cohorts. With mean post-HCT follow up of 4.5 (3.9) and 5.1 (4.1) years in Hb AA and Hb AS donor cohorts (p=0.145), no significant differences were seen in recipient outcomes including time to neutrophil and platelet engraftment, number of or time to last platelet transfusion, myeloid or unsorted % donor chimerism, number with acute (day 100) or chronic GVHD (1 year), or time to discontinue immunosuppression (data not shown). Disease recurrence and need for 2 nd HCT were rare in both cohorts (AA: 2 [3%] and 2 [3%]; AS: 3 [3%] and 4 [3%]; p=0.665 and 1.0, respectively). Two (3%) and 5 (4%) patients died in the AA and AS cohorts, respectively (p=1.0). Aside from a statistically (but not clinically) significant difference in Hb at day 30 (p=0.044), no difference was seen in longitudinal Hb or markers of hemolysis (LDH and ARC; Figure). No significant difference was seen in median number of RBC units transfused (AA: 4.0 [2.0-6.0]; AS: 3.0 [2.0-6.0]; p=0.454) or days to last transfusion (AA: 23.0 [14.0-77.0]; AS: 22.0 [13.0-75.0]; p=0.86). SCD complications were rare post-HCT, with no difference seen between cohorts in number (%) with VOC (AA: 1 [2%; had 2 separate VOC events]; AS: 3 [3%]; p=1.0), ACS (none reported), chronic pain (AA: 0 [0%]; AS: 1 [&amp;lt;1%]; p=1.0), or other SCD-related complications (AA: 2 [3%]; AS: 9 [7%; had 11 separate other events]; p=0.456). Stroke occurred in a significantly higher proportion with an AA versus AS donor (5 [8%] and 2 [2%], respectively; p=0.04). No significant differences were seen in longitudinal (1 and 2 years and at last follow up) post-HCT cardiac (EF, SF, TRJ velocity), pulmonary (FEV1, FVC, DLCO), or renal (GFR) function between cohorts (data not shown). Our results indicate that in MRD HCT for SCD, AS and AA donors yield comparable long-term outcomes. In this retrospective and registry-based study design, detailed analyses did not show differences between the two cohorts at baseline or at any timepoint post-HCT. While there were some outcome differences between the cohorts, they were either not clinically significant or did not have a scientific rationale, and thus were likely due to chance alone (denoted by bolding in Table). Given the young age of our cohort at HCT and thus a smaller proportion with SCD-related organ dysfunction, our results may not be applicable to an older cohort with significant organ dysfunction which will require a separate analysis.

Effect of Sickle Cell Trait on the Treatment Response of Individuals Infected with Human Immune-Deficiency Virus (HIV)

Background: Sickle cell disease is of public health importance and comes with systemic organ complications that can cause long-term disabilities and early death.&#x0D; Aim: This study was to determine the effect of co-existence between sickle cell gene (HbS) and HIV infection in a Lagos population.&#x0D; Methods: The study was conducted at the anti-retroviral (ARV) outpatient clinic of the Nigerian Institute of Medical Research (NIMR), Yaba, Lagos. It is a cross-sectional cohort study of 292 adult HIV- positive patients who were enrolled for treatment and support in the centre between the year 2004-2015. A review of case notes and database was done to extract haematologic, immunologic, virologic and clinical information of the patients. The enrolled participants were invited for additional clinical and socio-demographic information using a structured questionnaire. Blood samples were collected and reanalysed to confirm the haemoglobin genotype. Data analysis was performed using SPSS software.&#x0D; Results: Out of 292 recruited patients, 274 participants had complete data of which 74.1%, 22.9% and 2.9% were HbAA, HbAS and HbAC respectively. Sickle cell trait (SCT) was found in 25.9% of the participants and there was no record of sickle cell disease (SCD). HbAA participants were found to have a higher viral load (87.5%) at baseline (P &lt; 0.001). For HbAA and SCT groups, treatment response over the years was similar with lower figures seen in SCT.&#x0D; Conclusion: It was concluded that lower HIV viraemia in SCT might mean a delay in HIV-1 disease progression and subsequently better quality of life for such patients.

Puretone Hearing Threshold Of Patients With Sickle Cell Disease In Kaduna, Nigeria

Background: Sickle Cell Disease (SCD) is characterised by the vaso-occlusive crisis, which can cause progressive cochlea damage resulting in hearing loss. Objective: This study aimed to determine the prevalence of hearing loss and establish the hearing threshold of patients with sickle cell disease at the study centre. Methods: We conducted a prospective cross-sectional study on participants with sickle cell disease and normal controls between 5-50 years of age. Otolaryngological examination and Pure tone audiometry were carried out on all participants in a soundproof booth at the National Ear Care Centre, Kaduna. The Sickle cell patients were randomly selected from the Sickle cell patient promotion centre Kaduna and Barau Dikko Teaching Hospital Kaduna. The collated data were analysed descriptively with the Statistical Package of Social Sciences. (SPSS version 25). Result: Sixty-two subjects with Sickle cell disease and 62 with normal (HbAA) controls were assessed. The ages of subjects ranged between 6-41 years, while the HbAA was 5–49 years, with mean ages of 14.8 ± 8.1 years for SCD and 20.8 ± 13.3 years for HbAA controls. The mean Puretone threshold of the adult with SCD in the right and left ears were 25.5dB and 25.15dB, while that of Paediatrics with SCD were 21.5dB and 21.4dB, respectively, and it is consistently higher in those with SCD than the controls but the difference was not statistically significant. The prevalence of hearing loss in SCD was 30.6% and 16.1% in the control group (χ2=3.65 and P=0.056). The prevalence of hearing loss in those &lt;15 years was 27%, and in those ≥15 years was 36% in the subjects with HbSS/HbSC. Among those with hearing losses, the majority had mild SNHL (89.7%) in the HbSS/HBSc and 94.4% in the HbAA group. Also, ten patients had bilateral affectation in HbSS/HbSC group compared to eight in the HbAA (χ2=3.94, P=0.021). Conclusion: The prevalence of hearing loss in patients with SCD is 30.6% and it is higher in those ≥15 years. Many cases are asymptomatic, hence the need for SCD patients in our environment to have their hearing checked regularly.

Micronutrient levels and haemato-biochemical status of patients with sickle cell anaemia at a tertiary hospital in Abakaliki, south-eastern Nigeria: a cross-sectional study

Introductionnutritional status is an under-studied environmental factor that can impact the phenotypic manifestations of patients with Sickle Cell Anaemia (SCA). This study aimed to define hemato-biochemical parameters and micronutrient status in patients with SCA.Methodsthis was a cross-sectional study of patients with SCA and hemoglobin genotype HBAA controls at a tertiary health facility in Abakaliki, from 2nd December 2020 to 31st March 2021. Plasma micronutrient levels, haemato-biochemical parameters were analyzed and anthropometric measurements obtained from all participants.Resultssixty participants with SCA had 58.3% females (mean age of 24.77±7.39 years) while controls had 50% females (mean age of 26.23 ± 8.44 years). The SCA group had significantly lowered calcium (2.733 ± 1.593 vs 1.846 ± 1.123 mmol/l; p=0.009) and magnesium (19.38 ± 6.37 vs 9.65 ± 1.38 mg/dl; p= < 0.001) levels but higher plasma iron (1.70 ± 0.89 vs 1.06 ± 0.53; p=0.001). Zinc and Copper did not reveal significant differences between the two groups. Chloride ion levels was significantly lower in the SCA patients (107.50 ± 17.42 vs 100.19 ± 12.92; p=0.026) while Alkaline phosphatase (ALP), bilirubin, total white blood cell (WBC) and platelets (PLT) count were higher compared with the HBAA group (255.72 ± 124.52 vs 134.56 ± 39.67; p= <0.001, 46.86 ± 25.03 vs 25.63 ± 18.80; p = 0.001, 13.21± 6.57 vs 6.10 ± 1.35; p= < 0.001 and 369.25 ± 138.11 vs 209.36 ± 47.85; p= <0.001).ConclusionCopper and zinc deficiency was not present in our population of SCA patients but, they had lower plasma calcium and magnesium levels and elevated levels of blilirubin, ALP, WBC and platelets PLT counts. These parameters can be explored in designing better management for patients with SCA

Distinct pattern and prevalence of Plasmodium falciparum dihydropteroate synthase gene mutations in children with sickle cell anaemia and haemoglobin AA in Benin City, Nigeria: the impact of HbAA.

specific mutations on the Plasmodium falciparum dihydropteroate synthase (Pfdhps) gene mediate sulphadoxine/pyrimethamine (SP) resistance and thus, pose a threat to the efficacy of SP-Intermittent Preventive Therapy (SP-IPT) in malaria chemoprevention in children, including those with sickle cell anaemia (SCA). This study determined the distinct pattern and prevalence of Pfdhps mutations in children with SCA and in those with homozygous haemoglobin A (HbAA) in Benin City, Nigeria; showing the impact of haemoglobin phenotype. this was a cross-sectional study involving children with SCA and HbAA. Those with successfully amplified Pfdhps genes were included in the study. Point mutations and mutant haplotypes of the Pfdhps gene were identified. Parasite density (PD) was determined by estimating the parasite numbers/μl of blood from the thick film. Descriptive, univariable and multivariable analysis were used appropriately. a total of 146 children: 71 with SCA and 75 with HbAA were recruited, with a mean age of 46.6 ± 13.0 and 36.4 ± 17.6 respectively; proportion of males were 45(63.4%) and 43(57.3%) respectively. I431V, S436A, A437G, A581G, and A613G mutations were present; but the K540E mutation was absent. ISGKAA 41(28.1%) and VAGKGS 61(41.8%) were the most prevalent mutant haplotypes in this study. The prevalence of VAGKGS haplotype 43(57.3%) was significantly higher in HbAA group compared to that 18(25.4%) in the SCA group (p < 0.001). The prevalence of ISGKAA in SCA group 25(35.2%) was significantly higher than that 16(21.3%) in the HbAA group (p=0.032). HbAA phenotype was the only significant predictor for the presence of the VAGKGS mutant haplotype (aOR: 3.0, 95%CI: 1.375 to 6.499; p=0.006). the HbAA phenotype was a significant predictor for the occurrence of the quintuple mutant haplotype (VAGKGS). The K540E mutation was absent; thus, SP-IPT can be explored in children younger than five years with SCA.

Artemisinin derivative-containing therapies and abnormal hemoglobin: Do we need to adapt the treatment?

Background: Artemisinin-based treatment in malaria patients with abnormal hemoglobin may be ineffective because of their genetic particularity, which could lead to resistance. The main purpose of this study was to assess the effect of artemisinin derivatives on in vivo parasite clearance according to erythrocyte variants. In vivo response was investigated through retrospective data obtained over a 42-day artemether-lumefantrine/artesunate amodiaquine efficacy protocol conducted from 2012 to 2016. Results: A total of 770 patients in Côte d’Ivoire attending the hospitals of Anonkoua-koute (Abidjan), Petit Paris (Korhogo), Libreville (Man), Dar es salam (Bouaké), Ayamé and Yamoussoukro with acute uncomplicated falciparum malaria were selected for successful hemoglobin typing. HbAS, HbSS, HbAC, and HbSC genotypes were found. Parasite clearance time was obtained for 414 patients. In the population with abnormal hemoglobin, parasite densities on admission and parasite clearance rates were significantly lower in the HbSC group compared to HbAA (p = 0.02 and p = 0.007, respectively). After PCR correction on day 42, the acute treatment rate was 100% for each group. Parasite half-life and time for initial parasitaemia to decline by 50 and 99% were longer for the HbSC group (p < 0.05). The study also investigated the prevalence of K13-propeller polymorphisms across different hemoglobin genotype groups. A total of 185 and 63 samples were sequenced in the HbAA group and patients with abnormal Hb, respectively. Only two nonsynonymous mutations D559N and V510M were found in the HbAA group. Conclusion: Although this study proved good efficacy of artemether-lumefantrine and artesunate amodiaquine in the treatment of uncomplicated Plasmodium falciparum malaria in patients with abnormal hemoglobin, the increased delay of parasite clearance may represent a threat to health in these patients in relation with sickle cell crisis, which could support selection of parasites resistant to artemisinin.

Immunoglobulin G responses against falciparum malaria specific antigens are higher in children with homozygous sickle cell trait than those with normal hemoglobin

BackgroundHigh Immunoglobulin G (IgG) response to Plasmodium falciparum antigens is associated with partial malaria protection in sickle hemoglobin (HbS) children. However, this response has been more studied in children with heterozygous sickle cell trait (HbAS) but little explored in those with homozygous sickle cell trait (HbSS). The current study was conducted to determine the IgG responses against specific Plasmodium falciparum antigens in children with homozygous sickle cell trait (HbSS) by comparing to those with normal hemoglobin (HbAA).MethodsA cross sectional study was conducted between April and July 2018 in Dar es Salaam tertiary hospitals. Parents were consented for their child to give about 5 ml of venous blood. IgG concentration from the blood plasma of 220 children (110 HbAA vs. 110 HbSS) were determined using indirect Enzyme Linked Immunosorbent Assay (ELISA). Then IgG medians were compared between the groups with prism 5 software (GraphPad) using Mann Whitney U test. Where the differences in age, hemoglobin levels and body weight between the groups was analyzed using independent sample t test. Multiple linear regressions were used to control cofounding variables such as body weight, age and hemoglobin level using statistical package for social sciences software (SPSS version 23). P value <0.05 was considered statistically significant.ResultsThe median IgG concentration to PfEBA-175, Pfg27, yPfs28C antigens were HbSS; 20.7 ng/ml (IQR; 18.1–25.6) vs. HbAA; 2.3 ng/ml (IQR; 1.21–3.04), HbSS; 2.76 ng/ml (IQR: 2.08–5.69) vs. HbAA; 1.36 ng/ml (IQR: 1.28–1.76), and HbSS; 26,592 ng/ml (IQR: 10817–41,462) vs. HbAA; 14,164 ng/ml (IQR; 3069–24,302) respectively (p < 0.0001 for all IgG). In both groups; age, body weight and hemoglobin level had no impact on the levels of IgG responses to Plasmodium falciparum antigens except for HbAA group which showed a significant increase in IgG against Pfg27 by 0.004 ng/ml with 1 g/dl increase in Hb level (p = 0.028).ConclusionsThis study found significant higher levels of specific Plasmodium falciparum IgG responses in children with homozygous sickle cell trait than those with normal hemoglobin.

Exacerbated metabolic changes in skeletal muscle of sickle cell mice submitted to an acute ischemia-reperfusion paradigm.

Sickle cell disease (SCD) is characterized by painful vaso-occlusive crisis. While there are several metabolic abnormalities potentially associated with muscular ischemia-reperfusion cycles that could be harmful in the context of SCD, the metabolic consequences of such events are still unknown. Ten controls (HbAA), thirteen heterozygous (HbAS), and ten homozygous (HbSS) SCD mice were submitted to a standardized protocol of rest-ischemia-reperfusion of the left leg during which adenosine triphosphate, phosphocreatine, and inorganic phosphate concentrations as well as intramuscular pH were measured using phosphorous magnetic resonance spectroscopy (MRS). Forty-eight hours later, skeletal muscles were harvested. Oxidative stress markers were then measured on the tibialis anterior. At the end of the ischemic period, HbSS mice had a lower pH value as compared with the HbAA and HbAS groups (P<0.01). During the reperfusion period, the initial rate of phosphocreatine resynthesis was lower in HbSS mice as compared with HbAA (P<0.05) and HbAS (P<0.01) animals. No significant difference among groups was observed regarding oxidative stress markers. HbSS mice displayed a higher intramuscular acidosis during the ischemic period while their mitochondrial function was impaired as compared with their HbAA and HbAS counterparts. These metabolic abnormalities could worsen the complications related to the pathology of SCD.

Hemoglobin E protects against acute Plasmodium vivax infections in a Kachin population at the China–Myanmar border

Hemoglobin E (HbE, β26 Glu-Lys) is the most prevalent hemoglobinopathy in Southeast Asia. This study aimed to determine whether HbE protects against clinical Plasmodium vivax malaria in Southeast Asia. In a case-control study performed in villages along the China-Myanmar border, we determined the prevalence of HbE in 257 villagers who had acute P. vivax infections and in 157 control healthy villagers. HbE in P. vivax patients (17.4%) was significantly less prevalent than in the healthy villager population (36.3%). Moreover, there was a complete lack of HbEE homozygotes in the vivax patients as compared to 9.5% prevalence in the healthy villagers. Using the HbAA group as the reference, both the HbEA heterozygotes and HbEE homozygotes had significantly lower odds of presenting with acute P. vivax infections. Furthermore, HbEA heterozygotes also had significantly lower P. vivax asexual parasite densities. HbEA did not affect the proportion of P. vivax patients with gametocytemia nor the gametocyte densities. HbE offers significant protection against the occurrence and parasite density of acute P. vivax infections and provides a renewed perspective on P. vivax malaria as a potentially strong driving force behind the high frequencies of HbE in the Kachin population.

Assessment of Oxygen Saturation Using Pulse Oximetry in Patients with Steady State HbSS

Background: The exact consequence of hypoxemia SCA is unclear, however, many studies have shown haemoglobin desaturation is common in patient with SCA even at steady state, and may predispose to several complications including pulmonary hypertension, stroke and acute chest syndrome. Therefore, detection of hypoxemia is important in patients with SCA. Objectives: We sought to compare SpO2 of patients with HbSS in steady state and healthy individuals with HbAA genotype; and to determine the prevalence of hypoxemia amongst HbSS patients during steady state. Materials and Methods: This is a prospective cross-sectional study involving ninety three adults with SCA in steady state and forty-eight healthy age and sex matched HbAA participants as controls. The oxygen saturation was recorded using a finger pulse oximeter (Suaoki, Model FS20A). Results: The HbSS patients had a significantly lower mean SpO2 of 95.5% ( 4.1) compared to 99.06% ( 1.14) for the healthy HbAA group (p=0.0001). Male and female HbSS patients had a comparable SpO2 (95.8% vs 96.1%, p=0.610). Similarly, mean SpO2 was similar in male and female HbAA group (p=0.258). The prevalence of hypoxemia among the HbSS patients was 30.25% compared to 2.7% amongst the HbAA. The lowest SpO2 recorded among the HbSS patients was 88%. Conclusion: The prevalence of hypoxemia in steady state HbSS patients was high. This finding underscores the importance of monitoring HbSS patients for prompt detection of hypoxemia, and to institute therapy where necessary to prevent complications including pulmonary hypertension and cerebrovascular disease.

Trace elements in children suffering from sickle cell anemia: A case-control study.

Information on serum albumin and trace elements among children suffering from Sickle Cell Anemia (SCA) was poorly documented in Africa. The aim of this study was to describe and to compare different values of trace elements with published reports from other parts of the world. We carried out a case-control study. Seventy-six steady state children suffering from SCA (Hb-SS). One hundred and fifty-two children were recruited with 76 (cases, Hb-SS) and 76 (control, Hb-AA) to compare the data. The mean age was 10.0years (SD=5.4) in SCA children and 9.2years (SD=4.7) in the control group. The mean level of zinc and magnesium were slightly lower in the Hb-SS group than in the Hb-AA group (P<.001). The first literature about trace elements in SCA is briefly reported in Central Africa. In our midst, zinc, magnesium, and selenium deficiencies underline the need for their systematic among all children with SCA to identify patients with these deficiencies and provide early management.

Congolese children with sickle cell trait may exhibit glomerular hyperfiltration: A case control study.

The prevalence of sickle cell trait is extremely high in sub-Saharan Africa. Recent studies have reported the impact of sickle cell carriers on renal function. However, data on renal abnormalities in children with sickle cell trait in this part of the world are unknown. In this report, we assess the glomerular function of children with sickle cell trait (SCT). A case control study was conducted to assess the glomerular function in 43 Congolese children with sickle cell trait (Hb-AS) matched for age to 65 children with sickle cell anemia in steady state (Hb-SS) and 67 normal controls (Hb-AA). There was a significant difference in the blood pressure levels between the Hb-AS group vs Hb-SS group (P<.05). The estimated glomerular filtration rate (eGFR) corrected for body surface area was increased in Hb-AS group compared to Hb-AA group, but there was no significant difference between the two groups (P=.48). At the same time, the eGFR was decreased, but no significantly so, in the Hb-AS group compared to the Hb-SS group (P=.19). The proportion of children with Hb-AS (16.3%) who had hyperfiltration was higher compared to the proportion (6.1%) found in the Hb-AA group, but lower compared to the proportion found in the Hb-SS group (30%). However, in both situations, the difference was not statistically significant. No case of proteinuria was detected in children with Hb-AS. It appears that at least one of six children with SCT had hyperfiltration. The findings could form a basis for further studies on this renal physiology among SCT individuals in Africa.

Are sickle cell anaemia and sickle cell trait predictive factors for periodontal disease? A cohort study.

Periodontal diseases are associated with bacterial challenge and the host immune response, and are also modulated by genetic factors. There is evidence that sickle cell anaemia (SCA) does not represent a risk factor for periodontal diseases. However, it is still unclear whether the heterozygous condition [sickle cell trait (SCT)] is associated with periodontal diseases. SCT is a genetic condition that can cause vaso-occlusive events, which may be associated with a propensity to bacterial infections. The aim of this study was to investigate the association of SCA and SCT with periodontal diseases by evaluating clinical and radiographic characteristics. The sample (n = 369) was selected and divided into two groups: exposed groups [HbSS (SCA genotype) and HbAS (SCT genotype) = 246] and a nonexposed group (HbAA = 123). HbAA consisted of individuals without SCA and SCT. The clinical parameters evaluated were plaque index, gingival index, calculus index, clinical probing depth, clinical attachment level, gingival recession, tooth mobility and furcation involvement. The percentage of alveolar bone loss was measured using a Schei ruler. Binomial and Poisson regressions were used to estimate correlations of interest (α = 0.05). None of the periodontal parameters was associated with SCA. SCT was associated with gingivitis (p = 0.041) and periodontitis (p = 0.002). Individuals with SCT had a lower plaque index (p = 0.044) but a higher calculus index (p = 0.003) and greater alveolar bone loss (p = 0.010) compared with subjects in the HbAA group. SCT can act as a predictor for establishment of periodontal diseases. There was no correlation between SCA and periodontal diseases.

Phenotypic Characterization the Townes Sickle Mice

The HbSS-Townes mouse model, developed in Dr. Tim Townes laboratory, University of Alabama, Birmingham (and kindly provided by him to our laboratory) were created on a mixed genetic background in which the murine adult α-globin genes were replaced with the human α-globin gene (genotype: Hba hα/hα) and the murine adult β-globin genes were replaced with human sickle βS- and fetal Aγ-globin gene fragments linked together (genotype: Hbb hAγβS/hAγβS) (Wu LC et al. Blood 2006;108: 1183-1188). HbSS-Townes mice have anemia, a shortened RBC half-life of 2.5 days and a severe disease phenotype. Control HbAA-Townes mice were created by replacing the murine globin genes with human α-globin gene (genotype: Hba hα/hα) and linked human βA- and fetal Aγ-globins (genotype: Hbb hAγβA/hAγβA), while HbAS-Townes heterozygous mice were developed by breeding HbAA and HbSS mice. Many laboratories are utilizing these mice but complete phenotypic description of these three models has not been described including: hematology, kidney and liver function, inflammatory markers, haptoglobin and hemopexin levels, red cell half-lives, organ histopathology and vascular responses to vaso-occlusive stimuli. Table 1 summarizes our findings.There was a clear difference in histopathology between the HbSS and other groups (HbAA and HbAS). HbSS mice had hepatic necrosis, increased erythropoiesis and increased hemosiderin within the liver and some subtle lesions involving the glomeruli in the kidneys. Additional findings were a marked increase in size of spleen (7.0-7.6 x by % body weights) attributed to severe congestion and increased erythropoiesis. No lesions were observed in the lungs and other tissues. The tissues evaluated in the HbAS and HbAA groups were essentially normal. In contrast, HbSS mice had multifocal irregular areas of necrosis within the liver, with reactive leukocyte infiltrates (mainly neutrophils in the more acute lesions with a greater proportion of mononuclear cells (macrophages etc.) in more chronic lesions. MPO immunohistochemistry confirmed the presence of neutrophils in the liver. There was a substantial increase in iron (and hemosiderin) in the livers of HbSS mice, confirmed by a Prussian Perls stain and low, but detectable, levels of iron in the proximal convoluted tubules of the kidney. This is consistent with increased red cell turnover in the HbSS mice. Total iron mass in the markedly enlarged spleen is very high. There is a somewhat subtle glomerulopathy present in the kidney, with enlarged glomeruli with variable ectasia of vessels, and mesangial derangement. In conclusion the Townes mouse models provide a spectrum of severe hemolytic disease that in many ways mimic the human disease albeit imperfectly. TableTable 1HbAAHbASHbSSHb (g/dL)12.0 ± 0.610.6 ± 0.59.5 ± 1.4*Hematocrit (%)49.6 ± 2.345.0 ± 4.2*29.2 ± 0.9*#WBC (K/µL)10.8 ± 1.213.2 ± 4.038.2 ± 4.9*#Platelet Counts (K/uL)854 ± 78889 ± 1421004 ± 179Monocytes (%)8.0 ± 1.17.6 ± 1.77.4 ± 1.0Lymphocytes (%)60 ± 3.063.8 ± 5.667.5 ± 9.1Neutrophils (%)28.6 ± 5.926.1 ± 8.727.8 ± 2.2Reticulocytes (%)7.8 ± 1.78.6 ± 4.556.8 ± 2.6*#RBC Half-Life (days)15.710.62.4Expired CO (nmoles/h/g)0.92 ± 0.241.27 ± 0.236.33 ± 1.08*Serum Bilirubin (mg/dl)3.5 ± 0.94.3 ± 0.65.6 ± 0.4*Urine Creatinine (mg/dL)44.1 ± 3.845.9 ± 3.856.2 ± 7.0*Urine Osmolality (mOsm/kg H2O)2147 ± 761707 ± 2651361 ± 32*Serum Haptoglobin (µg/ml)39.3 ± 3.80.5 ± 0.2*2.3 ± 1.4*Serum Hemopexin (µg/ml)802 ± 266169 ± 51*124 ± 35*Serum SAP (µg/ml)20.9 ± 7.214.1 ± 12.086.7 ± 20.2*#Stasis at 1h in Response to Hb (%)10.0 ± 3.219.8 ± 2.7*30.0 ± 3.4*#Mortality at 24h in Response to Heme (%)00100*#Liver % of Body Weight4.95 ± 0.484.39 ± 0.356.22 ± 0.21*#Spleen % of Body Weight0.79 ± 0.140.87 ± 0.396.61 ± 0.75*#Kidney % of Body Weight0.65 ± 0.270.72 ± 0.190.73 ± 0.24Liver Necrosis Score0.0 ± 0.00.25 ± 0.502.38 ± 0.25*Liver Fe Score0.0 ± 0.00.25 ± 0.53.0 ± 0.0*Lung Fe Score0.0 ± 0.00.0 ± 0.0*1.0 ± 0.0*#Spleen Fe Score3.0 ± 0.03.0 ± 0.02.0 ± 0.0*#Kidney Fe Score0.0 ± 0.00.25 ± 0.51.75 ± 0.5*#Liver Gr1 Score1.0 ± 0.01.25 ± 0.52.25 ± 0.5*Lung Gr1 Score1.0 ± 0.01.0 ± 0.01.25 ± 0.5Spleen Gr1 Score1.5 ± 0.62.0 ± 0.02.0 ± 0.0Kidney Gr1 Score0.25 ± 0.50.25 ± 0.50.75 ± 0.5* p<0.05 vs HbAA; # p<0.05 vs HbAS DisclosuresNo relevant conflicts of interest to declare.

Renal function in children suffering from sickle cell disease: challenge of early detection in highly resource-scarce settings.

BackgroundThe prevalence of Sickle cell disease is extremely high in Democratic Republic of Congo. Despite this high prevalence of the disease, data on renal abnormalities in children are rare.MethodThe study proposed to assess blood pressure, glomerular function, urea and uric acid levels in 65 steady state Congolese children with homozygous sickle cell disease and 67 normal controls.ResultsIn Hb-SS group, blood pressure level tended to be lower than Hb-AA groups but there was no statistically significant difference (p>0.05) between the two groups. The absolute values for GFR corrected for BSA were significantly higher in Hb-SS group compared to Hb-AA group (130.5±34.1 ml/min/1.73 m2 vs 113.7±24.5 ml/min/1.73 m2; p = 0.004). Children with Hb-SS were more likely to hyperfiltrate (30.8% of subjects) than children with Hb-AA (6.1% of subjects). Proteinuria was found in 4 (6.2%) children with Hb-SS. Uric acid level was significantly increased in children with Hb-SS compared to corresponding values in control group (4.4±1.3 mg/dl vs 3.5±1.1 mg/dl; p<0.001). Urea level was significantly decreased compared to corresponding values in Hb-AA group (15.3±8.3 mg/dl vs 22.9±10.1 mg/dl; p<0.001).ConclusionHyperfiltration, low creatinine, lower urea and high uric acid are more common in children with sickle cell disease than in normal controls.

Sickle Cell Trait: Is There an Increased VTE Risk in Pregnancy and the Postpartum?

Blacks are purported to have a higher venous thromboembolism (VTE) risk than whites. We hypothesized that this might be due, in part, to the greater presence of sickle cell trait (SCT) among blacks. We investigated whether the presence of SCT resulted in a higher VTE incidence in a population predisposed to VTE, the pregnant/postpartum women. Methods: Using a mirrored clinical database that prospectively gathered in- and out-patient information for the years 1998–2008, we collected demographic data, including hemoglobin electrophoreses, on all pregnant/postpartum non-Hispanic women who delivered at a large, diverse, urban hospital. We identified those women who developed VTE either while pregnant or postpartum during those 11 years. Charts initially identified as potential VTE cases were subjected to review to ensure accuracy of VTE coding. Results: Of 12,429 women, 679 non-Hispanic SCT black women, 5,465 non-Hispanic Hemoglobin AA (women with HbA as the only hemoglobin present on electrophoresis, with normal amounts of the minor hemoglobins) black women and 1,162 non-Hispanic HbAA white women were included in the analysis. SCT prevalence was high (11.1%) within this black population as compared to 8.3% in the general non-white population. Proportions with VTE were similar for black SCT and black HbAA groups: 0.44% for the SCT group, 0.49% for non-Hispanic black HbAA women. Black HbAA women had a non-significantly higher proportion of VTE than white HbAA women 0.49% vs 0.26% (RR 1.9, 95%CI:0.6,6.3, p = 0.28). Women with VTE were older than those without VTE (32.2 vs. 27.6 years, p = 0.0002) and the majority of VTE occurred postpartum in all groups, and significantly in the HbAA groups. There was no increase in the incidence of pulmonary emboli in the SCT group. Conclusion: In the largest analysis to date, we could not detect a meaningful difference in peripartum VTE incidence between women with and without sickle cell trait.

Increased Angiogenic Activity of Plasma From Sickle Cell Disease Patients and Anti-Angiogenic Effects of Hydroxyurea: Evaluation of Capillary-Like Structure Formation of Human Umbilical Vein Endothelial Cells on Matrigel

Abstract 899Sickle cell disease (SCD) results from mutations in the β chain of hemoglobin and is associated with a complex pathophysiological process that involves endothelial activation, inflammation and oxidative stress. Several clinical aspects of SCD such as pulmonary hypertension, moyamoya vasculopathy, proliferative retinopathy and leg ulcers suggest the involvement of an unbalanced angiogenesis. Plasma levels of vascular endothelial growth factor, placenta growth factor, angiopoietin-1 and angiopoietin-2 are reportedly elevated in SCD, although the effects of these alterations on angiogenic mechanisms in SCD are unclear. Hydroxyurea (HU) has been used successfully for SCD therapy and may act through several mechanisms. The purpose of this study was to evaluate the effects of plasma obtained from SCD patients upon capillary-like structure formation of human umbilical vein endothelial cell (HUVEC) cultures on Matrigel. Patients (in steady state) and controls were divided into six groups: HbSS phenotype not treated with HU (SSHU−), HbSS treated with HU (SSHU+), HbSC phenotype with retinopathy not treated with HU (SCR+HU−), HbSC without retinopathy and not treated with HU (SCR-HU−), HbSC with retinopathy and treated with HU (SCR+HU+) and control individuals (HbAA). Patients on HU had been taking 20–30mg/kg/day for at least 3 months. To assess tube formation, HUVECs (5× 104cells/mL) were cultured on growth factor reduced-Matrigel coated plates in the presence of 10% plasma and the number of cord-like structures quantified. Photomicrographs were taken using a phase-contrast inverted microscope. HUVEC were also incubated with HU (50–200 μM) and migration (double-chamber assay), proliferation (BrdU assay) and capillary-like structure formation (Matrigel) were addressed to compare effects of plasma from patients treated with HU to medium containing HU alone. After 17 H of incubation, a small decrease in HUVEC tube formation (4.1 ±4.9%, n=5, P>0.05 comp. to control, HUVEC in medium alone) was observed in the presence of HbAA group plasma, in agreement with reports suggesting an antiangiogenic activity of human plasma in absence of diseases. In contrast, angiogenesis of HUVEC increased significantly in the presence of plasma from all SCD patients, independently of retinopathy, as demonstrated by increases in tube formation indexes of 32.5 ±7.5%, 15.8 ±9.2%, 30.0 ±4.4% (N=5, P<0.05 comp. control, ANOVA-Dunnet) for the SSHU−, SCR-HU− and SCR+HU−, respectively. Notably, HUVEC cultures containing plasma from patients treated with HU presented considerably less angiogenesis compared to control cultures. The ability of HUVEC to form branching and thick anastomosing capillaries on Matrigel was inhibited by SSHU+ and SCR+HU+ plasma; furthermore, tube formation indexes decreased by 61.7 ± 8.8% and 92.3 ±2.9% in the presence of these plasmas (P<0.001, n= 5/2 respect.). In experiments conducted with just HU (200μM, n=5) in the HUVEC medium, significant decreases in cell migration (51.1 ± 3.45%; P<0.001), proliferation capacity (49.4 ± 4.66%; P<0.001) and capillary-like structure formation 75.8 ± 4.1% (P<0.001) were observed. Importantly, MTT (tetrazolium salt) assays showed that none of the plasmas nor HU was cytotoxic to HUVEC at the concentrations used. Angiogenesis is a complex process, where multiple contributing factors can have opposing effects. Plasma is rich in proteins that regulate angiogenesis and our data indicate that plasma from SCD patients is highly pro-angiogenic at a biologically-relevant level. Interestingly, we detected no significant difference between SC and SS individuals, although plasma from SC individuals with retinopathy was significantly more angiogenic than that of SC individuals without retinopathy. The highly anti-angiogenic capacity of plasma from patients treated with HU suggests that one of the beneficial effects of this drug may be inhibition of angiogenesis. Data suggest that the HU drug itself may be capable of regulating angiogenesis by attenuating migration, proliferation and tube formation; however, since the half-life of HU is about 3–4 H, these anti-angiogenic effects are probably not mediated directly by this drug, but by newly-generated molecule(s) with a longer half-life. In conclusion, our study highlights the possible role of angiogenesis in SCD pathophysiology and suggests that SCD patients could be candidates for anti-angiogenic therapy. Disclosures:No relevant conflicts of interest to declare.

Influence of Sickle Cell Trait on the Risk of Venous Thromboembolism In Pregnancy and the Postpartum

AbstractAbstract 1628 Background:Evidence suggests a disparity in the incidence of venous thromboembolic events (VTE) amongst racial groups, with blacks purported to have a higher occurrence of VTE than whites. In contrast, Hispanics and Asians have been observed to have a lower occurrence of VTE. Sickle cell anemia is a known prothrombotic state and recent studies contend that sickle cell trait (SCT) may also predispose to VTE. We hypothesized that SCT might play a role in the increased VTE risk for blacks. To this end, we conducted a study to investigate whether pregnant/postpartum women with SCT have a higher VTE incidence than controls without SCT. Methods:Patient information was obtained using our hospital database spanning the eleven years 1998–2008. All pregnant women seen in our large urban medical center had hemoglobin (Hb) electrophoresis screening on their first clinic visit; demographic data was obtained from the patient at registration. Using prospectively-collected data, three patient cohorts were identified. Group A included women with SCT as identified by %HbS of 30–45% on Hb electrophoresis. To ensure exclusion of patients with sickle cell disease who were post-transfusion, subjects who at any time in their medical record had %HbS >45% were excluded from analysis. HbAA black (Group B) and white (Group C) cohorts were included if %HbA was ≥95.5%. Women who self-identified themselves as Hispanic, multiracial, “declined”, “not available” or “not applicable” were also excluded. VTE cases were identified using ICD-9 codes from hospital, ER or outpatient visit discharges during the pregnancy or postpartum period (294 days before delivery or 56 days after delivery). All charts of VTE indexed cases were reviewed (by SP) to ensure accuracy of reporting. Results:The prevalence of SCT was found to be high (11.1%) in our Group A population as compared to 8.3% in the general pregnant/postpartum non-white population that included Hispanics, multiracial and unavailable individuals. We identified 679 black subjects with SCT, 5465 black subjects with HbAA and 1162 white subjects with HbAA. VTE incidence was 0.44% in Group A (SCT), in 0.49% in Group B (Black AA) and in 0.26% in Group C (White AA). The rate of VTE did not significantly differ between these groups. When patients were included who had been thromboprophylaxed secondary to previous VTEs, the incidence of VTE in Black AA was 0.6%, still not significantly different from the white AA group (p=0.13). Age was a more important factor: patients with VTE were significantly older than non-VTE pregnant patients (mean 32.2 vs. 27.6 years, p=0.0002). As expected, the majority of VTE occurred in the postpartum period (61%). Conclusion:Our results suggest that there is a nonsignificant trend toward a higher incidence of VTE in black HbAA (Group B) as compared to white women with HbAA (Group C) in the pregnant/postpartum period. We could not detect a difference in VTE incidence between black SCT (Group A) and black HbAA (Group B). The role of sickle cell trait as an inherited prothrombotic mutation remains unclear. Even a mild increase in age appears to constitute a prothrombotic risk. However, as VTE remains one of the major causes of maternal mortality, further studies will be needed to better identify risk factors of VTE in pregnancy. Prospective studies identifying such patients may help characterize the true impact of sickle cell trait on venous thromboembolism in pregnancy and postpartum. Disclosures:No relevant conflicts of interest to declare.