scholarly journals Blood mononuclear cell gene expression profiles characterize the oxidant, hemolytic, and inflammatory stress of sickle cell disease

Blood ◽  
2004 ◽  
Vol 104 (1) ◽  
pp. 270-280 ◽  
Author(s):  
Maria L. Jison ◽  
Peter J. Munson ◽  
Jennifer J. Barb ◽  
Anthony F. Suffredini ◽  
Shefali Talwar ◽  
...  
Keyword(s):  
Gene Expression ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Expression Profiles ◽  
Ischemia Reperfusion ◽  
Transcriptional Analysis ◽  
Heme Oxygenase 1 ◽  
Specific Gene ◽  
Cell Disease

Abstract In sickle cell disease, deoxygenation of intra-erythrocytic hemoglobin S leads to hemoglobin polymerization, erythrocyte rigidity, hemolysis, and microvascular occlusion. Ischemia-reperfusion injury, plasma hemoglobin-mediated nitric oxide consumption, and free radical generation activate systemic inflammatory responses. To characterize the role of circulating leukocytes in sickle cell pathogenesis we performed global transcriptional analysis of blood mononuclear cells from 27 patients in steady-state sickle cell disease (10 patients treated and 17 patients untreated with hydroxyurea) compared with 13 control subjects. We used gender-specific gene expression to validate human microarray experiments. Patients with sickle cell disease demonstrated differential gene expression of 112 genes involved in heme metabolism, cell-cycle regulation, antioxidant and stress responses, inflammation, and angiogenesis. Inducible heme oxygenase-1 and downstream proteins biliverdin reductase and p21, a cyclin-dependent kinase, were up-regulated, potentially contributing to phenotypic heterogeneity and absence of atherosclerosis in patients with sickle cell disease despite endothelial dysfunction and vascular inflammation. Hydroxyurea therapy did not significantly affect leukocyte gene expression, suggesting that such therapy has limited direct anti-inflammatory activity beyond leukoreduction. Global transcriptional analysis of circulating leukocytes highlights the intense oxidant and inflammatory nature of steady-state sickle cell disease and provides insight into the broad compensatory responses to vascular injury.

Increased Inflammatory State and Metabolic Activation in Neutrophils from Patients with Sickle Cell Disease: Comparison of Neutrophil Gene Expression Profiles with Controls.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3571-3571
Author(s):  
Sule Bakanay ◽  
Ferdane Kutlar ◽  
Joshi Ratanmani ◽  
Betsy Clair ◽  
Leigh Wells ◽  
...  
Keyword(s):  
Gene Expression ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Disease Severity ◽  
Sickle Cell ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Disease ◽  
Expression Of Genes ◽  
Inflammatory State

Abstract Chronic inflammation is a well-established feature of sickle cell disease (SCD) even at steady state, and the degree of inflammation tends to correlate with disease severity. Elevated neutrophil count, as a reflection of the overall inflammatory state, has emerged as an indicator of poor prognosis and has been associated with adverse outcomes including stroke and early mortality. To further delineate the role of neutrophils in the pathogenesis of various complications and in overall disease severity in SCD, we analyzed the gene expression profiles of neutrophils from 5 patients with "severe" disease (>3 vaso-occlusive episodes [VOE] per year), 5 patients with "mild" disease (<3 VOE/year) and compared these to each other and to the gene expression profiles of neutrophils from 5 age and sex matched, healthy, non-sickle cell, African-American individuals. Granulocytes were separated from freshly collected venous blood using Histopaque (Sigma diagnostic) density gradient separation. Total RNA was extracted immediately after cell separation by using Rneasy Mini Kit (Qiagen). 2 micrograms of total RNA was converted to double stranded cDNA (ds-cDNA) by using SuperScript Choice System (Invitrogen). In vitro transcription was performed on the ds-cDNA using Enzo RNA transcript labelling kit. After the fragmentation, labeled RNA was hybridized to a set of oligonucleotide arrays (HG U133A, Affymetrix, Santa Clara, CA) and the data was analysed with the Microarray suite 5.0 software (Affymetrix). Out of the differentially expressed genes (314 genes for severe vs. control, 718 genes for mild vs control), those with greater than two fold expression were analysed with the geneMAPP software for localization into biological pathways. In general, a larger number of genes were differentially expressed between "mild" patients vs. control, compared to that between "severe" vs "mild" patients. Genes related to cellular proliferation, growth and maintenance, DNA repair, DNA replication, and cell cycle progression were expressed at significantly higher levels in SCD patients compared to controls. The most impressive finding was the significantly higher expression of genes leading to NFkB activation and inhibition of apoptosis: IAP-1 (increased 6.7 fold and 4.7 fold in mild and severe patients respectively), IkB (decreased 0.14 fold and 0.3 fold), Apaf-1 (decreased 0.4 fold in mild), and c-jun (decreased 0.4 fold in severe); Traf-2 (TNF receptor associated factor-2; increased 3.5 fold and 2 fold); genes in the MAPK signalling pathway: ERK-2 (increased 3.5 fold and 2-fold), MAP2K3 (increased 3.5 fold and 2 fold). These data show that neutrophils in SCD patients are activated with higher expression of genes in the TNF, MAPK, and NFkB pathways consistent with an inflammatory state. Delayed or inhibited apoptosis of neutrophils further maintains this inflammatory state even during the so-called "steady state" of the disease. We conclude that the analyses of gene expression in neutrophils can be a useful tool in identifying pathways and genes that distinguish SCD patients from controls and in differentiating mild and severe phenotypes.

Amplified Expression Profiling of Platelet Transcriptome Reveals Global Activation of Arginine Metabolic Pathways in Patients with Sickle Cell Disease.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1536-1536
Author(s):  
Nalini Raghavachari ◽  
Xiuli Xu ◽  
Jose Villagra ◽  
Greg Kato ◽  
Peter J. Munson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Expression Profiles ◽  
Ischemia Reperfusion ◽  
Functional Characterization ◽  
Gene Set Enrichment Analysis ◽  
Clinical Samples ◽  
Cell Disease ◽  
Activated State

Abstract In sickle cell disease, ischemia-reperfusion injury and intravascular hemolysis produce endothelial dysfunction and vasculopathy characterized by reduced nitric oxide (NO) and arginine bioavailability. Recent functional studies of platelets in patients with sickle cell disease reveal a basally activated state, suggesting that pathological platelet activation may contribute to sickle cell disease vasculopathy. Studies were therefore undertaken to globally examine transcriptional signaling pathways in platelets that may be dysregulated in sickle cell disease. We demonstrate and validate here the feasibility of comparative platelet transcriptome studies on clinical samples from single donors, by the application of RNA amplification followed by microarray-based analysis of 54,000 probe sets. Data mining for platelet specific or abundant genes identified 118 genes that showed more than a 100-fold increase in transcript expression level compared to all other cells in the database. Most of these genes were clearly annotated as platelet-specific and 84% of these transcripts overlapped with the platelet abundant genes identified in previous gene expression studies. On comparing the platelet gene expression profiles in 18 patients with sickle cell disease in steady state to 12 African American controls, at a 3-fold cut-off and 5% false discovery rate, we identified >100 differentially expressed genes, including multiple genes involved in arginine/NO metabolism and redox homeostasis. Further functional characterization of these pathways using Gene Set Enrichment Analysis, real time PCR, arginase enzymatic assay, and polyamine quantification revealed arginase II-mediated catabolism and diversion of arginine from NO signaling and polyamine synthesis to proline formation. These studies suggest a potential pathogenic role for platelet arginase and ornithine decarboxylase antizyme and provide a novel framework for the study of disease-specific platelet biology.

Hospitalization for Acute Pain in Sickle Cell Disease: Changes in Clinical Parameters and Factors Predicting Hospital Discharge and Re-Admission

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3662-3662
Author(s):  
Mehdi Nouraie ◽  
Debra L Weiner ◽  
Mariana Hildesheim ◽  
Ward Hagar ◽  
Oswaldo L Castro ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Hospital Stay ◽  
Sickle Cell ◽  
Research Funding ◽  
Ischemia Reperfusion ◽  
Serum Lactate Dehydrogenase ◽  
Index Hospitalization ◽  
Cell Disease ◽  
Readmission Risk

Abstract Introduction: Acute vaso-occlusive crisis (VOC) is the hallmark clinical complication of sickle cell disease (SCD). VOC involves several mechanisms, including rigid erythrocytes, adhesive blood cells, activated coagulation, activated and dysregulated endothelium, inflammation, and ischemia-reperfusion injury. Surprisingly few data document clinical and laboratory markers that change from steady state to VOC and during the hospital stay, and that predict subsequent rehospitalization. We characterized such markers in this study. Methods: Data were collected as part of a clinical trial of nitric oxide as potential treatment for VOC (DeNOVO). Participants, age ≥ 10 years requiring hospitalization for VOC, were recruited from 11 academic medical centers at the time of VOC. Length of hospital stay (LOS), change in visual analogue scale (VAS) pain score, and hospital readmission within 30 days were study outcomes. Steady state laboratory values were available in a subgroup of patients for comparison. Differences between admission and steady state laboratory measures and changes in clinical and laboratory parameters from hospital admission to discharge were analyzed by Wilcoxon signed-rank test. Multivariate linear and logistic regression analyses were used to identify the independent predictors of LOS and 30-day readmission risk. Results: 150 recruited patients had a median (interquartile range; IQR) age of 24 (17-33) years; 50% were female, and 91% had HbSS genotype. The median VAS score at time of admission was 7.7 cm which subsided to 3.3 cm at time of discharge (P &lt;0.001). Serum lactate dehydrogenase concentrations (LDH) and neutrophils counts increased from steady state to the time of the VOC (P ≤ 0.001) and then decreased during the hospital stay (P ≤ 0.01) (Figure). The median (IQR) LOS was 3.5 (1.9-6.0) days. Longer LOS was predicted by higher admission VAS and serum alkaline phosphatase level, as well as higher increase in respiratory rate during hospital stay (P ≤ 0.006) (Table). The rate of 30-day hospital/ED readmission was 24%. Longer LOS was associated with lower risk of readmission (OR = 0.65, 95% CI: 0.50-0.86 per day). Other risk factors for readmission were higher serum creatinine at discharge (OR = 5.54, 95% CI: 1.12-27.51 per mg/dL), greater increase in serum alanine aminotransferase (OR = 1.03, 95%CI: 1.01-1.06 per unit increase) and greater cumulative opioid doses (OR = 1.25, 95%CI: 1.11-1.49 per 100 mg) during the index hospitalization. Conclusion: VOC is associated with neutrophilia and increased LDH, consistent with inflammation and hemolysis and/or tissue injury, although of insufficient magnitude to be used as diagnostic criteria. The magnitude of pain and marker of apparent bone involvement predict longer LOS. SCD patients with VOC carry a high burden of readmission risk, which is characterized by higher opioid utilization and earlier discharge from the index hospitalization. These concepts can shape models, especially to reduce readmission rate, to be evaluated in prospective clinical trials. *First two authors contributed equally to this work. Figure Figure. Table Table. Disclosures Lanzkron: NKT: Research Funding; Selexys: Research Funding; Prolong: Research Funding; PCORI: Research Funding; NHLBI: Research Funding; HRSA: Research Funding; GBT: Consultancy; Pfizer: Research Funding.

Determinants Of Heme-Oxygenase-1 Upregulation In Patients With Sickle Cell Disease

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2235-2235 ◽  
Author(s):  
Olufolake Adisa ◽  
Benjamin Yaw Owusu ◽  
Yijuan Hu ◽  
Samit Ghosh ◽  
Fang Tan ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Heme Oxygenase ◽  
Sickle Cell ◽  
Conflicts Of Interest ◽  
Dinucleotide Repeat ◽  
Acute Chest Syndrome ◽  
Heme Oxygenase 1 ◽  
Cell Disease ◽  
The Mean

Abstract Inflammation is a cardinal component of the pathogenesis of sickle cell disease (SCD). Increased plasma concentration of the inflammatory agonist hemin increases the odds of acute chest syndrome (ACS) in children with SCD (Adisa et al., Br. J Haematol, 2013). In addition, free hemin promotes the development of a lethal ACS-like disease in transgenic sickle mice (Ghosh et al., J Clin Invest, 2013). Hemin degradation is controlled by the rate-limiting enzyme heme oxygenase-1 (HO-1). Polymorphism of a (GT)n dinucleotide repeat in the HO-1 promoter, which enhances expression of the gene, is associated with lower rates of hospitalization for ACS in children. Over-expression of HO-1 reduces stasis in a mouse model of SCD vaso-occlusion. However, the role of plasma HO-1 in SCD patients is entirely unknown. In this study, we measured steady-state plasma HO-1 in two cohorts of patients. Cohort 1 in Atlanta (n=98) consisted of children with a mean age of 10.07±0.42 years (range 2-19 years) and cohort 2 from Accra (n=80) consisted of older patients (mean age 25.30±1.0 years, range 13-58 years). The mean plasma HO-1 of both cohorts was significantly higher compared to the mean value of age- and ethnic-matched individuals with normal adult Hb; Atlanta: 10.19±5.80 vs. 2.08± 1.16, p<0.0001 and Accra: 13.7±8.14 vs. 2.57± 0.82, p<0.0001. Plasma HO-1 varied by 25-fold in both cohorts and it correlated with the white blood cell count (Atlanta: r=0.3361, p<0.0001, Accra: r=0.25, p=0.02). Fifty-four percent (n=53) of subjects in the Atlanta cohort were on hydroxyurea. The mean plasma HO-1 of this subgroup was lower (8.1 ± 4.5) compared to the hydroxyurea naïve Accra cohort (p=<0.0001). Further studies of the Accra cohort revealed significant correlations between HO-1 and multiple markers of vascular inflammation; sICAM-1(r=0.2794, p=0.03, n=60), sE-selectin (r= 0.4209, p=0.0017, n=58) and sP-selectin (r=0.3855, p=0.0028, n=58). The number of the (GT)n dinucleotide in the HO-1 promoter ranged 17 to 45; the distribution was trimodal with peaks at 23, 30 and 41 repeats. The overwhelming majority of patients had medium and large size alleles that are generally hypo-response to induction. Plasma HO-1 level correlated with the length of the (GT)n dinucleotide repeat (p=0.003, n=80). In a multivariable regression model, WBC, sICAM-1, sE-selectin and sP-selectin accounted for 13.4% of the total variance of plasma HO-1 level, and the (GT)n polymorphism accounted for 9.8%. In conclusion, the concentration of plasma HO-1 is generally raised among SCD patients at steady-state. However, a large proportion of patients have a relatively modest level that is probably inadequate to counter the severity of inflammation typical of SCD, due in part to a hypo-responsive HO-1 promoter. Therapeutic strategies that complement induction of the endogenous HO-1 gene may be critical to ameliorate inflammation in SCD. Disclosures: No relevant conflicts of interest to declare.

Differentially Expressed Genes and Pathways in Endothelial Cells Exposed to Hemin or Plasma from Patients with Sickle Cell Disease: A Meta-Analysis of Gene Expression Studies

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4018-4018
Author(s):  
Maiara M L Fiusa ◽  
Marina Pereira Colella ◽  
Joyce M Annichino-Bizzacchi ◽  
Loredana Nilkenes ◽  
Bidossessi W Hounpke ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endothelial Cells ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Meta Analysis ◽  
P Value ◽  
Cell Disease ◽  
Expression Studies ◽  
Gene Expression Studies

Abstract Introduction: Vaso-occlusion and chronic hemolysis are recognized as the most important pathogenic mechanisms of sickle cell disease (SCD), feeding a vicious circle that leads to acute and chronic complications. Although phenotypic aspects of this pro-inflammatory state have been described in detail, much less is known about the upstream pathways that activate and perpetuate inflammation in SCD. It has been known for more than 50 years that patients with SCD present higher plasma concentrations of heme. More recently, the role of heme as a mediator of inflammation in SCD has been confirmed in relevant models, suggesting that free heme can be a trigger for both microvascular occlusion and acute chest syndrome (ACS). In the past, microarray-based gene expression experiments have been used to study the effects of heme on endothelial cells (EC), as well as gene expression signatures of SCD. These studies can be analyzed in combination, since original raw data are now collected in public archives. In fact, it has been shown that by analyzing data from multiple experiments by meta-analysis, biases and artifacts between datasets can be cancelled out, potentially allowing true relationships to stand out. In order to gain insights into the cellular and molecular pathways activated by heme in endothelial cells (EC), as well as about their potential relevance in SCD, we performed a meta-analysis of microarray-based gene expression studies involving heme, EC and SCD. Material and methods: Microarray data were identified by searching two public databases (GEO and Array-Express) using the following search criteria: (“sickle cell disease” and “homo sapiens”). Eleven studies were identified, of which two were selected for our meta-analysis (GSE1849; GSE25014). One study evaluated the effect of heme 5µM in human primary pulmonary artery (PAECs) and microvascular EC (PMVECs) (12 samples), while the other study evaluated the effect of plasma from SCD patients (9 patients in steady state and 12 patients during ACS) in PAECs. To perform the meta-analysis we used INMEX, an integrative web-based tool for meta-analysis of expression data. For the meta-analysis, we applied a combining rank orders method based in the RankProd package. Genes with expression fold-changes (FC) in the same direction (either up or down) of 1.4 in at least one study were selected as candidates for differentially expressed (cDE) genes. Selected genes were ranked based on p value, and a p value ≤0.05 was considered statistically significant. To further understand functions of the subset of genes that were cDE in both studies, we performed gene ontology enrichment analysis. The functional analysis was undertaken using INMEX, and confirmed in other three gene set analysis tools (Pathway Commons, WikiPathways and KEGG). Only pathways that were identified in more than one tool were considered in the analysis. Results: Two different meta-analysis were performed. Gene expression data from heme-stimulated EC was compared to: (i) data from EC stimulated by plasma from SCD patients at steady-state; or (ii) data from EC stimulated by plasma obtained during ACS. In the first (heme x steady-state) and second (heme x ACS) analysis, 799 and 786 genes were consistently up- or down-regulated in both studies. The up- and down-regulated genes with the lowest p values were C2CD4A (C2 calcium-dependent domain containing 4A), and KLHL23 (kelch-like family member 23), respectively. In addition, genes associated with depletion of reactive oxygen species and coagulation activation were also identified. The most significant pathways identified in the gene set analysis were “IL5-mediated signaling events” (heme x steady-state; p= 0.0012) and “MAPK signaling pathway” (heme x ACS; p= 0.0073512) respectively. Results and conclusion: Genes and pathways that are DE both in EC stimulated by heme or by plasma from SCD patients could be relevant elements in the pathogenesis of inflammation in SCD. Heme has been shown to increase the generation of ROS and to induce the expression of inflammatory and pro-coagulant proteins by EC. The results of our meta-analysis are consistent with these effects. Therefore, the comprehensive list of genes and pathways identified in our study could help the generation new hypothesis about the mechanisms involved in heme-induced activation and perpetuation of inflammation in SCD. Disclosures No relevant conflicts of interest to declare.

scholarly journals Neutrophil gelatinase–associated lipocalin as a biomarker of nephropathy in sickle cell disease

2021 ◽  
Author(s):  
Rajaa Marouf ◽  
Adekunle D. Adekile ◽  
Hadeel El-Muzaini ◽  
Rasha Abdulla ◽  
Olusegun A. Mojiminiyi
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Roc Curve ◽  
Screening Tests ◽  
Cell Disease ◽  
Urine Ngal ◽  
Neutrophil Gelatinase Associated Lipocalin ◽  
Plasma Ngal ◽  
Neutrophil Gelatinase

AbstractSickle cell nephropathy (SCN) develops via altered hemodynamics and acute kidney injury, but conventional screening tests remain normal until advanced stages. Early diagnostic biomarkers are needed so that preventive measures can be taken. This study evaluates the role of neutrophil gelatinase–associated lipocalin (NGAL) as a biomarker of SCN in steady state and vaso-occlusive crisis (VOC). In this case-control study, 74 sickle cell disease (SCD) patients (37 in steady state and 37 in VOC) and 53 control subjects had hematological and biochemical measurements including plasma and urine NGAL. Univariate and logistic regression analyses were used to find the associations between variables. The receiver operating characteristic (ROC) curve was used to determine the diagnostic performance characteristics of plasma and urine NGAL for detection of VOC. Plasma and urine NGAL, urine microalbumin:creatinine ratio, and urine protein:creatinine ratio were significantly higher in VOC. Microalbuminuria was present in 17.1% steady state and 32.0% VOC patients. Microalbuminuria showed significant correlations with age, plasma NGAL, WBC, and hemolytic parameters. Area under the ROC curve for plasma NGAL was 0.69 (95%CI = 0.567–0.813; p = 0.006) and 0.86 (95%CI = 0.756–0.954; p < 0.001) for urine NGAL. Urine NGAL cut-off value of 12.0 ng/mL had 95% sensitivity and 65% specificity. These results confirm the presence of nephropathy during VOC and suggest that plasma and urine NGAL would be useful in the identification of SCN. Urine NGAL should be used as the screening biomarker, and patients with VOC and urine NGAL > 12.0 ng/mL should be selected for aggressive management to prevent progression of renal damage.

scholarly journals Effects of Genotypes and Treatment on Oxygenscan Parameters in Sickle Cell Disease

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 811
Author(s):  
Camille Boisson ◽  
Minke A. E. Rab ◽  
Elie Nader ◽  
Céline Renoux ◽  
Celeste Kanne ◽  
...  
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Blood Cell ◽  
Sickle Cell ◽  
Red Blood Cell ◽  
Cell Disease ◽  
Oxygen Gradient ◽  
Acute Complication ◽  
Adults And Children ◽  
The Difference

(1) Background: The aim of the present study was to compare oxygen gradient ektacytometry parameters between sickle cell patients of different genotypes (SS, SC, and S/β+) or under different treatments (hydroxyurea or chronic red blood cell exchange). (2) Methods: Oxygen gradient ektacytometry was performed in 167 adults and children at steady state. In addition, five SS patients had oxygenscan measurements at steady state and during an acute complication requiring hospitalization. (3) Results: Red blood cell (RBC) deformability upon deoxygenation (EImin) and in normoxia (EImax) was increased, and the susceptibility of RBC to sickle upon deoxygenation was decreased in SC patients when compared to untreated SS patients older than 5 years old. SS patients under chronic red blood cell exchange had higher EImin and EImax and lower susceptibility of RBC to sickle upon deoxygenation compared to untreated SS patients, SS patients younger than 5 years old, and hydroxyurea-treated SS and SC patients. The susceptibility of RBC to sickle upon deoxygenation was increased in the five SS patients during acute complication compared to steady state, although the difference between steady state and acute complication was variable from one patient to another. (4) Conclusions: The present study demonstrates that oxygen gradient ektacytometry parameters are affected by sickle cell disease (SCD) genotype and treatment.

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.

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