Activated monocytes in sickle cell disease: potential role in the activation of vascular endothelium and vaso-occlusion

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2451-2459 ◽  
Author(s):  
John D. Belcher ◽  
Paul H. Marker ◽  
Jill P. Weber ◽  
Robert P. Hebbel ◽  
Gregory M. Vercellotti
Keyword(s):  
Endothelial Cells ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Nuclear Translocation ◽  
Mononuclear Leukocytes ◽  
Cell Contact ◽  
Cell Disease ◽  
Tnf Α ◽  
Activated Monocytes

Sickle cell anemia is characterized by painful vaso-occlusive crises. It is hypothesized that monocytes are activated in sickle cell disease and can enhance vaso-occlusion by activating endothelium. To test this hypothesis, human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (MVEC) with sickle and normal mononuclear leukocytes were incubated, and endothelial activation was measured. Endothelial cells incubated with sickle mononuclear leukocytes were more activated than those incubated with normal mononuclear leukocytes, as judged by the increased endothelial expression of adhesion molecules and tissue factor and the adhesion of polymorphonuclear leukocytes (PMNL). Monocytes, not lymphocytes or platelets, were the mononuclear cells responsible for activating endothelial cells. Sickle monocytes triggered endothelial nuclear factor-kappa B (NF-κB) nuclear translocation. Cell-to-cell contact of monocytes and endothelium enhanced, but was not required for, activation. Antibodies to tumor necrosis factor-alpha (TNF-α) and interleukin-1-beta (IL-1β) blocked activation of the endothelium by monocytes. Peripheral blood monocytes from patients with sickle cell disease had 34% more IL-1β (P = .002) and 139% more TNF-α (P = .002) per cell than normal monocytes. Sixty percent of sickle monocytes expressed the adhesion molecule ligand CD11b on their surfaces compared with only 20% of normal monocytes (P = .002). Serum C-reactive protein, a marker of systemic inflammation, was increased 12-fold in sickle serum than in normal serum (P = .003). These results demonstrate that sickle monocytes are activated and can, in turn, activate endothelial cells. It is speculated that vascular inflammation, marked by activated monocytes and endothelium, plays a significant role in the pathophysiology of vaso-occlusion in sickle cell anemia.

Activated monocytes in sickle cell disease: potential role in the activation of vascular endothelium and vaso-occlusion

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2451-2459 ◽  
Author(s):  
John D. Belcher ◽  
Paul H. Marker ◽  
Jill P. Weber ◽  
Robert P. Hebbel ◽  
Gregory M. Vercellotti
Keyword(s):  
Endothelial Cells ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Nuclear Translocation ◽  
Mononuclear Leukocytes ◽  
Cell Contact ◽  
Cell Disease ◽  
Tnf Α ◽  
Activated Monocytes

Abstract Sickle cell anemia is characterized by painful vaso-occlusive crises. It is hypothesized that monocytes are activated in sickle cell disease and can enhance vaso-occlusion by activating endothelium. To test this hypothesis, human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (MVEC) with sickle and normal mononuclear leukocytes were incubated, and endothelial activation was measured. Endothelial cells incubated with sickle mononuclear leukocytes were more activated than those incubated with normal mononuclear leukocytes, as judged by the increased endothelial expression of adhesion molecules and tissue factor and the adhesion of polymorphonuclear leukocytes (PMNL). Monocytes, not lymphocytes or platelets, were the mononuclear cells responsible for activating endothelial cells. Sickle monocytes triggered endothelial nuclear factor-kappa B (NF-κB) nuclear translocation. Cell-to-cell contact of monocytes and endothelium enhanced, but was not required for, activation. Antibodies to tumor necrosis factor-alpha (TNF-α) and interleukin-1-beta (IL-1β) blocked activation of the endothelium by monocytes. Peripheral blood monocytes from patients with sickle cell disease had 34% more IL-1β (P = .002) and 139% more TNF-α (P = .002) per cell than normal monocytes. Sixty percent of sickle monocytes expressed the adhesion molecule ligand CD11b on their surfaces compared with only 20% of normal monocytes (P = .002). Serum C-reactive protein, a marker of systemic inflammation, was increased 12-fold in sickle serum than in normal serum (P = .003). These results demonstrate that sickle monocytes are activated and can, in turn, activate endothelial cells. It is speculated that vascular inflammation, marked by activated monocytes and endothelium, plays a significant role in the pathophysiology of vaso-occlusion in sickle cell anemia.

Effect of Hydroxyurea Treatment on In Vitro Adhesion of Sickle Erythrocytes to Sickle Leukocyte Subpopulations.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 362-362
Author(s):  
Eileen M. Finnegan ◽  
Aslihan Turhan ◽  
Jennifer Gaines ◽  
David E. Golan ◽  
Gilda Barabino
Keyword(s):  
T Cells ◽  
Endothelial Cells ◽  
T Cell ◽  
Sickle Cell Disease ◽  
Adhesion Molecules ◽  
Sickle Cell ◽  
Cell Disease ◽  
Tnf Α ◽  
Adhesive Interactions ◽  
Cell Cell

Abstract Microvascular vaso-occlusion in sickle cell disease is thought to involve adhesive interactions among erythrocytes (RBCs), leukocytes and vascular endothelial cells. Recent studies have demonstrated the presence of a significant inflammatory response in sickle cell disease, including changes in the cell surface adhesion molecules that mediate cell-cell interactions in the microvasculature. In this study, we used a parallel-plate flow chamber assay to determine the subpopulations of leukocytes that are involved in sickle leukocyte-RBC interactions. We also studied the effect of treatment with hydroxyurea (HU) on these adhesive interactions. Populations of monocytes, neutrophils (PMNs) and T cells were isolated by negative selection from the peripheral blood of untreated patients with sickle cell disease (SS), sickle patients receiving HU (SS-HU), and healthy control subjects (AA). Adhesive interactions involving these leukocyte subpopulations, human umbilical vein endothelial cells (HUVECs) pretreated with tumor necrosis factor-α (TNF-α ), and autologous RBCs were measured under a shear stress of 1 dyne/cm2. Compared to the corresponding cell populations from AA individuals, PMNs, monocytes, and T cells from SS individuals were significantly more adherent to TNF-α-treated HUVECs (774±59 vs. 502±27 cells/mm2, p=0.001; 533±66 vs. 348±36 cells/mm2, p=0.024; and 470±75 vs. 227±26 cells/mm2, p=0.009, respectively). HU therapy significantly decreased the adhesion of SS PMNs to HUVECs (774±59 cells/mm2 for SS vs. 604±36 for SS-HU, p=0.025). Compared to adherent AA leukocytes, adherent SS leukocytes exhibited greater participation in adhesive interactions with autologous RBCs (41±3% for SS vs. 27±3% for AA, p=0.002), and HU treatment decreased the fraction of leukocytes that captured autologous RBCs to the control level (29±3% for SS-HU, p=0.006 vs. SS). Compared to adherent PMNs from SS individuals, adherent PMNs from SS-HU individuals showed significantly reduced participation in the capture of RBCs (53±6% for SS vs. 35±5% for SS-HU, p=0.021). Although adherent T cells from SS individuals participated significantly more in RBC capture than adherent T cells from AA individuals (28±5% for SS vs. 10±2% for AA, p=0.007), HU therapy did not have a significant effect on this parameter (21±5% for SS-HU, p=0.373). Compared to AA leukocytes, SS leukocytes captured more RBCs per participating adherent leukocyte (2.8±0.2 vs. 1.9±0.1 RBCs/cell, p=0.001). HU therapy reduced the number of RBCs captured per PMN but not the number captured per T cell. Compared to AA T cells, SS T cells captured adherent RBCs for a significantly longer period of time (51±9 vs. 26±6 seconds, p=0.035). Our data suggest that sickle neutrophils, monocytes and T cells may all be involved in adhesive interactions with sickle RBCs. PMN-RBC and monocyte-RBC interactions appear to be more numerous than T cell-RBC interactions, although T cell-RBC interactions may be stronger. HU therapy appears to target PMN-RBC and monocyte-RBC interactions preferentially. Future studies will focus on the role of particular adhesion molecules in mediating these interactions and on the potential for therapeutic interventions targeting cell-cell adhesion.

Heme Induces Endothelial Tissue Factor Expression: Potential Role in Hemostatic Activation in Patients with Intravascular Hemolysis Including Sickle Cell Disease.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1902-1902
Author(s):  
Yamaja Setty ◽  
Suhita Gayen Betal ◽  
Jie Zhang ◽  
Nigel S Key ◽  
Marie Stuart
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Whole Blood ◽  
Dependent Manner ◽  
Cell Disease ◽  
Intravascular Hemolysis ◽  
Tnf Α ◽  
Endothelial Tissue

Abstract Plasma levels of heme in the 20 to 600 μM range are found in clinical conditions associated with intravascular hemolysis including paroxysmal nocturnal hemoglobinuria and sickle cell disease, conditions also associated with a thrombotic tendency. Objectives: To investigate whether heme, an inflammatory mediator and a product of intravascular hemolysis in patients with hemolytic anemia including sickle cell disease (SCD), could modulate hemostasis by an effect on endothelial tissue factor (TF) expression. Additionally, in SCD patient-related studies, we assessed whether any association existed between whole blood TF activity (WBTF) and levels of surrogate markers of intra-vascular hemolysis including lactate dehydrogenase (LDH) and reticulocyte counts. Methods: Following incubation of human endothelial cells (from umbilical vein and/or lung microvasculature) with heme (1 to 100 μM) for various times (30 minutes to 8 hours), levels of TF protein were assessed using ELISA, flow cytometry and/or Western blotting; and TF mRNA by a semi-quantitative RT-PCR. An assay for TF functional activity was performed using a chromogenic tenase activity kit where specificity of TF activity was tested in antibody-blocking experiments. Three TF-specific antibodies including a rabbit polyclonal and two mouse monoclonal (clones hTF-1 and TF9-10H10) antibodies were used in assays involving TF protein analysis. All experiments were performed in media containing polymyxin B to neutralize any potential endotoxin contamination. In patient-related studies, 81 subjects with SCD (1 to 21 years) were evaluated for levels of WBTF, LDH, and reticulocyte counts and data analyzed for potential relationships. Results: Heme induced TF protein expression on the surface of both macro- and micro-vascular endothelial cells in a concentration-dependent manner with 12- to 50-fold induction noted (ELISA assays) between 1 and 100 μM heme (P<0.05, n=3 to 6). Complementary flow cytometry studies showed that the heme-mediated endothelial TF expression was quantitatively similar to that induced by the cytokine TNF-α. Heme also up-regulated endothelial expression of TF mRNA (8- to 26-fold, peak expression at 2 hours postagonist treatment), protein (20- to 39-fold, peak expression at 4 hours) and procoagulant activity (5- to 13-fold, peak activity at 4 hours post-agonist treatment) in a time-dependent manner. Time-course of heme-mediated TF antigen expression paralleled induction of procoagulant activity with antibody blocking studies demonstrating specificity for TF protein. Potential involvement of endogenously released cytokines including IL-1α and TNF-α in mediating the heme effect was next explored. We found that the latter cytokines are not involved, since antibodies against IL-1α and TNF-α, and an IL-1- receptor antagonist failed to block heme-induced endothelial TF expression. Inhibition of heme-induced TF mRNA expression by sulfasalazine and curcumin suggested that the transcription factor NFκB was involved in mediating heme-induced effect. In patient-related studies, whole blood TF levels in SCD correlated positively with both LDH (r=0.72, p<0.000001), and reticulocyte count (r=0.60, p<0.000001). Conclusions: Our findings demonstrate that heme induces TF expression in endothelial cells, and that the observed effects occurred at patho-physiologically relevant heme concentrations. Our results suggest that heme-induced endothelial TF expression may provide a pathophysiologic link between the intravascular hemolytic milieu and the hemostatic perturbations previously noted in patients with hemolytic anemia including sickle cell disease.

The Adhesion of Sickle Cell Disease Neutrophils to Endothelial Layers, In Vitro, Is Mediated by the Mac-1, LFA-1 and VLA-4 Integrins.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2264-2264 ◽  
Author(s):  
Andreia A. Canalli ◽  
Renata F. Proenca ◽  
Sara T.O. Saad ◽  
Nicola Conran ◽  
Fernando F. Costa
Keyword(s):  
Endothelial Cells ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Umbilical Vein ◽  
In Vivo Studies ◽  
Integrin Subunit ◽  
Cell Disease ◽  
Inflammatory Conditions ◽  
Tnf Α

Abstract Leukocytes may have a propagating and, possibly, initiating role in sickle cell disease (SCD) vaso-occlusion. In vivo studies suggest that adherent leukocytes capture sickle erythrocytes in the microcirculation and in vitro studies demonstrate an increased ability of SCD neutrophils (neu) to adhere to fibronectin, endothelial cells and endothelial proteins. Previous studies suggest that the expressions of the major neu integrins, CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1) may only be upregulated on the surface of SCD neu following their stimulation, indicating that alterations in integrin function (affinity or avidity) contribute to alter SCD neu adhesion. The objective of this study was to identify the integrins responsible for altered SCD neu adhesion. Neus were isolated from the peripheral blood of healthy controls and SCD individuals in steady state over ficoll-paque gradients. Cell adhesion (2×106cells/ml in RPMI) to cultured human umbilical vein endothelial cells (HUVEC) at confluence was assessed using static adhesion assays (30min, 37°C, 5%CO2). Neus from SCD patients demonstrated a significantly greater adhesion to HUVEC than control neus (20.2±2.8% compared to 11.2±1.0%; n≥7; p<0.03; Mann Whitney test). Subsequently, cells were co-incubated with adhesion molecule-blocking monoclonal antibodies (mAbs) during assays. Control neu adhesion to HUVEC was significantly inhibited by the anti-CD11b mAb (6.7±1.5%;n=6; P<0.05, paired t test), but not by mAbs against CD11a, the VLA-4-integrin subunit, CD49d, or a non-specific negative control mAb (neg control) (data not shown). In contrast, the adhesion of SCD neus to HUVEC was significantly inhibited by both the anti-CD11a and the anti-CD11b mAbs (20.2±2.8% reduced to 11.4±1.2% and 9.1±1.5%; n=9; P<0.01 and P<0.001, respect.). Interestingly, a mAb against CD49d was also found to significantly decrease SCD neu adhesion to HUVEC (10.4±1.1%; n=9; P<0.01), while the neg control mAb did not significantly affect SCD neu adhesion (data not shown). Following the stimulation of HUVEC with TNF-α (10 ng/ml) (3h, 37°C, 5%CO2) to simulate an endothelial layer under inflammatory conditions, the adhesions of control and SCD neus were increased but statistically similar (38.4±2.9% and 34.4±5.0%; n≥4, respect.). Under these conditions anti-CD11a and CD11b mAbs significantly inhibited control neu adhesion to HUVEC (reduced to 28.8±2.9% and 19.6±4.6%; n=4; P<0.01 and P<0.05, respect.). In contrast, SCD neu adhesion to HUVEC was significantly inhibited by mAbs for CD11a (19.5±2.6%; n=6; p<0.01) and CD11b (15.2±2.0%; n=6; p<0.001). The anti-CD49d, but not the neg control mAb, also significantly decreased SCD neu adhesion to TNF-α-stimulated HUVEC (19.5±3.7%; n=6; p<0.05). In conclusion, data indicate that control neu adhesion to endothelial cells appears mainly to be mediated by the Mac-1 (CD11b/18) integrin with a contribution from the LFA-1 integrin (CD11a/18) under inflammatory conditions. In contrast, SCD neu adhesion to endothelium (under both basal and stimulated conditions), at least in vitro, appears to be mediated by the Mac-1 and LFA-1 integrins and, interestingly, by VLA-4 (CD49d/CD29), an integrin found expressed at low levels on neus during certain inflammatory conditions. We speculate that alterations in the affinity/ avidity of these molecules contribute to SCD neu adhesion. Approaches to inhibit the adhesion of all three integrins may be important for preventing leukocyte adhesion to the vascular endothelium and, in turn, vaso-occlusion.

scholarly journals Is there a role for selective vasodilation in the management of sickle cell disease?

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 597-602 ◽  
Author(s):  
GP Rodgers ◽  
MS Roy ◽  
CT Noguchi ◽  
AN Schechter
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Microvascular Obstruction ◽  
Controlled Study ◽  
Control Group ◽  
Cell Disease ◽  
Retinal Arteriolar

Abstract To test the hypothesis that microvascular obstruction to blood flow at the level of the arteriole may be significant in individuals with sickle cell anemia, the ophthalmologic effects of orally administered nifedipine were monitored in 11 steady-state patients. Three patients with evidence of acute peripheral retinal arteriolar occlusion displayed a prompt reperfusion of the involved segment. Two other patients showed fading of retroequatorial red retinal lesions. Color vision performance was improved in six of the nine patients tested. The majority of patients also demonstrated a significant decrease in the amount of blanching of the conjunctiva which reflects improved blood flow to this frequently involved area. Such improvements were not observable in a control group of untreated stable sickle cell subjects. These findings support the hypothesis that inappropriate vasoconstriction or frank vasospasm may be a significant factor in the pathogenesis of the microvascular lesions of sickle cell disease and, further, that selective microvascular entrapment inhibition may offer an additional strategy to the management of this disorder. We believe a larger, placebo-controlled study with nifedipine and similar agents is warranted.

Pathogenesis of Hyposthenuria in Sickle Cell Anemia

PEDIATRICS ◽  
1960 ◽  
Vol 26 (6) ◽  
pp. 1051-1051
Author(s):  
Clarence L. Morgan
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Genetic Defect ◽  
Urine Osmolality ◽  
Normal Kidney ◽  
Cell Disease

Schlitt and Keitel report (Pediatrics, 26: 249, 1960) complete reversibility of hyposthenuria in a 6-month-old subject with sickle cell disease following transfusion over a 4-day period of 290 ml of blood with a rise in maximal urine osmolality from 700 to 1100 mosmol/l. They cite this as evidence against an independent genetic defect being causal in the etiology of hyposthenuria in sickle cell disease. It is well known that the concentrating capacity of the normal kidney increases as the ratio of urea to other solutes in the urine approaches 0.35, and the approximate range of improvement may be from 650 to 1100 mosmol/l.1

PATHOGENESIS OF HYPOSTHENURIA IN PERSONS WITH SICKLE CELL ANEMIA OR THE SICKLE CELL TRAIT

PEDIATRICS ◽  
1960 ◽  
Vol 26 (2) ◽  
pp. 249-254
Author(s):  
L. Schlitt ◽  
H. G. Keitel
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Renal Damage ◽  
Sickle Cell Trait ◽  
Urinary Concentration ◽  
Cell Disease ◽  
Renal Vessels

Hyposthenuria was investigated in subjects with sickle cell trait and in patients with sickle cell anemia. The following were observed: 1) in subjects with sickle cell trait both normal and reduced maxima of urinary concentration are found, whereas all untreated patients with sickle cell anemia over 6 months of age have hyposthenuria; 2) hyposthenuria becomes increasingly more severe with advancing age in both sickle cell anemia and sickle cell trait; 3) in a 6-month-old patient with sickle cell anemia and hyposthenuria, the maxima of urinary concentration returned to normal after two transfusions of normal erythrocytes. Reasons are presented for favoring the hypothesis that hyposthenuria in sickle cell disease is due to renal damage, possibly from intravascular sickling of erythrocytes in renal vessels or from the presence of "free" circulating S-hemoglobin.

scholarly journals Ischemic Stroke in Children and Young Adults with Sickle Cell Disease (SCD) in the Post-STOP Era

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 68-68 ◽  
Author(s):  
Janet L. Kwiatkowski ◽  
Julie Kanter ◽  
Heather J. Fullerton ◽  
Jenifer Voeks ◽  
Ellen Debenham ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
High Risk ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Stroke Prevention ◽  
Cell Disease ◽  
Clinical Series ◽  
The Mean

Abstract Background: The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) established routine transcranial Doppler ultrasound (TCD) screening with indefinite chronic red cell transfusions (CRCT) for children with abnormal TCD as standard of care. To identify children at high-risk of stroke, annual TCD screening is recommended from ages 2 to 16 years, with more frequent monitoring if the result is not normal. A reduction in stroke incidence in children with SCD has been reported in several clinical series and analyses utilizing large hospital databases when comparing rates before and after the publication of the STOP study in 1998. We sought to determine the rate of first ischemic stroke in a multicenter cohort of children who had previously participated in the STOP and/or STOP 2 trials and to determine whether these strokes were screening or treatment failures. Subjects and Methods: Between 1995 and 2005, STOP and STOP 2 (STOP/2) were conducted at 26 sites in the US and Canada. These studies included 3,835 children, ages 2 to 16 y with SCD type SS or S-beta-0-thalassemia. Participation in STOP/2 ranged from a single screening TCD to randomization. STOP 2 also had an observational arm for children on CRCT for abnormal TCD whose TCD had not reverted to normal. The Post-STOP study was designed to follow-up the outcomes of children who participated in one or both trials. 19 of the 26 original study sites participated in Post-STOP, contributing a total of 3,539 (92%) of the STOP/2 subjects. After exit from STOP/2, these children received TCD screening and treatment according to local practices. Data abstractors visited each clinical site and obtained retrospective data from STOP/2 study exit to 2012-2014 (depending on site) including follow-up TCD and brain imaging results, clinical information, and laboratory results. Two vascular neurologists, blinded to STOP/2 status and prior TCD and neuroimaging results, reviewed source records to confirm all ischemic strokes, defined as a symptomatic cerebral infarction; discordant opinions were resolved through discussion. For the first Post-STOP ischemic stroke, prior TCD result and treatment history subsequently were analyzed. Results: Of the 3,539 subjects, follow-up data were available for 2,850 (81%). Twelve children who had a stroke during STOP or STOP2 were excluded from these analyses resulting in data on 2,838 subjects. The mean age at the start of Post-STOP was 10.5 y and mean duration of follow-up after exiting STOP/2 was 9.1 y. A total of 69 first ischemic strokes occurred in the Post-STOP observation period (incidence 0.27 per 100 pt years). The mean age at time of stroke was 14.4±6.2 (median 13.8, range 3.5-28.9) y. Twenty-five of the 69 patients (36%) had documented abnormal TCD (STOP/2 or Post-STOP) prior to the stroke; 15 (60%) were receiving CRCT and 9 (36%) were not (treatment data not available for 1 subject). Among the 44 subjects without documented abnormal TCD, 29 (66%) had not had TCD re-screen in the Post-STOP period prior to the event; 7 of these 29 (24%) were 16 y or older at the start of Post-STOP, which is beyond the recommended screening age. Four of the 44 (9%) patients had inadequate TCD in Post-STOP (1 to 10.7 y prior to event). Six (14%) had normal TCD more than a year before the event (1.2 - 4 y); all but one of these children were younger than 16 y at the time of that TCD. Only 5 (11%) had a documented normal TCD less than 1 year prior to the event. Conclusions: In the Post-STOP era, the rate of first ischemic stroke was substantially lower than that reported in the Cooperative Study of Sickle Cell Disease, prior to implementation of TCD screening. Many (39%) of the Post-STOP ischemic strokes were associated with a failure to re-screen according to current guidelines, while only 11% occurred in children who had had recent low-risk TCD. Among those known to be at high risk prior to stroke, treatment refusal or inadequate treatment may have contributed. While TCD screening and treatment are effective at reducing ischemic stroke in clinical practice, significant gaps in screening and treatment, even at sites experienced in the STOP protocol, remain to be addressed. Closing these gaps should provide yet further reduction of ischemic stroke in SCD. Disclosures No relevant conflicts of interest to declare.

scholarly journals Asymmetric Dimethyl Arginine Level in Children with Sickle Cell Disease: A Cross Sectional Study

2021 ◽  
pp. 93-98
Author(s):  
Seham Fathy Khedr ◽  
Mohamed Hosny El Bradaey ◽  
Hala Mohamed Nagy ◽  
Mohamed Ramadan El-Shanshory ◽  
Eslam Elhawary
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cell Disease ◽  
Adma Level ◽  
Cross Sectional ◽  
Asymmetric Dimethyl Arginine ◽  
Dimethyl Arginine

Background: Sickle cell disease (SCD) consists of a group of hemoglobinopathies in which individuals inherit hemoglobin variants derived from single point mutations. Asymmetric dimethylarginine (ADMA) contributes to limiting Nitric Oxide (NO)  bioavailability in SCD. The aim of the present study was to assess the level of the Asymmetric Dimethyl Arginine in children with sickle cell. Methods: This cohort cross-sectional study was carried out on 60 children which were divided in to 3 equal groups. Group I: SCD children with sickle retinopathy. Group II: SCD children without retinopathy. Group III: healthy control children who were selected from the outpatient clinic. Results: There was a significant increase in ADMA level among participants withSCD. There was a positive significant correlation between ADMA  level and family history as well as the  incidence of hepatomegaly. There was no significant correlation between ADMA level and demographic and laboratory parameters except LDH. Conclusions: The level of ADMA is elevated in children with sickle cell anemia. High plasma ADMA level is a risk for hepatomegaly in children with sickle cell anemia.

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