Assessment of total and unbound cell-free heme in plasma of patients with sickle cell disease.

Intravascular hemolysis results in the release of cell-free hemoglobin and heme in plasma. In sickle cell disease, the fragility of the sickle red blood cell leads to chronic hemolysis, which can contribute to oxidative damage and activation of inflammatory pathways. The scavenger proteins haptoglobin and hemopexin provide pathways to remove hemoglobin and heme, respectively, from the circulation. Heme also intercalates in membranes of blood cells and endothelial cells in the vasculature and associates with other plasma components such as albumin and lipoproteins. Hemopexin has a much higher affinity and can strip heme from the other pools and detoxify plasma from cell-free circulatory heme. However, due to chronic hemolysis, hemopexin is depleted in individuals with sickle cell disease. Thus, cell-free unbound heme is expected to accumulate in plasma. We developed a methodology for the accurate quantification of the fraction of heme, which is pathologically relevant in sickle cell disease, that does not appear to be sequestered to a plasma compartment. Our data show significant variation in the concentration of unbound heme, and rather unexpectedly, the size of the unbound fraction does not correlate to the degree of hemolysis, as measured by the concentration of bound heme. Very high heme concentrations (>150 µM) were obtained in some plasma with unbound concentrations that were several fold lower than in plasma with much lower hemolysis (<50 µM). These findings underscore the long-term effects of chronic hemolysis on the blood components and of the disruption of the essential equilibrium between release of hemoproteins/heme in the circulation and adaptative response of the scavenging/removal mechanisms. Understanding the clinical implications of this loss of response may provide insights into diagnostic and therapeutic targets in patients with sickle cell disease.

Non-transfusion-dependent thalassemia and thalassemia intermedia: epidemiology, complications, and management.

OBJECTIVE: The non-transfusion-dependent thalassemias (NTDTs), including thalassemia intermedia (TI), hemoglobin E beta thalassemia, and hemoglobin H disease, have sometimes been regarded as less severe than their transfusion-dependent variants; however, these disorders carry a substantial disease burden (e.g., splenomegaly, iron overload, skeletal effects, and cardiopulmonary disease). The aim of this review is to increase clinician awareness of the growing global problem of NTDT and TI, and discuss the current management strategies for these conditions. METHODS: Recent peer-reviewed articles (publication years 2000 through 2015) addressing the epidemiology, complications, management, and monitoring of NTDT were identified in the PubMed database and reviewed. RESULTS: The changing epidemiology of thalassemia constitutes a growing health problem. Increased clinician awareness is necessary for the appropriate diagnosis and management of patients with NTDT. CONCLUSIONS: Management of NTDT requires a comprehensive approach, beginning with screening and prenatal diagnosis, monitoring for iron overload and associated complications, and iron chelation therapy. Several novel strategies are in the early stages of investigation and may help increase treatment options in patients with NTDT. Importantly, ethnic or cultural barriers may exist within the affected populations and need to be considered in the management approach.

A potent oral P-selectin blocking agent improves microcirculatory blood flow and a marker of endothelial cell injury in patients with sickle cell disease.

Abnormal blood flow accounts for most of the clinical morbidity of sickle cell disease (SCD) [1,2]. Most notably, occlusion of flow in the microvasculature causes the acute pain crises [3] that are the commonest cause for patients with SCD to seek medical attention [4] and major determinants of their quality of life [5]. Based on evidence that endothelial P-selectin is central to the abnormal blood flow in SCD we provide results from four of our studies that are germane to microvascular blood flow in SCD. A proof-of-principle study established that doses of heparin lower than what are used for anticoagulation but sufficient to block P-selectin improved microvascular blood flow inpatients with SCD. An in vitro study showed that Pentosan Polysulfate Sodium (PPS) had greater P-selectin blocking activity than heparin. A Phase I clinical study demonstrated that a single oral dose of PPS increased microvascular blood flow in patients with SCD. A Phase II clinical study that was not completed documented that daily oral doses of PPS administered for 8 weeks lowered plasma levels of sVCAM-1 and tended to improve microvascular blood flow in patients with SCD. These data support the concept that P-selectin on the microvascular endothelium is critical to both acute vascular occlusion and chronically impaired microvascular blood flow in SCD. They also demonstrate that oral PPS is beneficial to microvascular sickle cell blood flow and has potential as an efficacious agent for long-term prophylactic therapy of SCD.

Assessment of cardiac iron by MRI susceptometry and R2* in patients with thalassemia.

A magnetic resonance imaging cardiac magnetic susceptometry (MRI-CS) technique for assessing cardiac tissue iron concentration based on phase mapping was developed. Normal control subjects (n=9) and thalassemia patients (n=13) receiving long-term blood transfusion therapy underwent MRI-CS and MRI measurements of the cardiac relaxation rate R2*. Using MRI-CS, subepicardium and subendocardium iron concentrations were quantified exploiting the hemosiderin/ferritin iron specific magnetic susceptibility. The average of subepicardium and subendocardium iron concentrations and R2* of the septum were found to be strongly correlated (r=0.96, P<.0001), and linear regression analysis yielded CIC (microg Fe/g(wet tissue))=(6.4+/-0.4).R2* (septum) (s(-1)) - (120+/-40). The results demonstrated that septal R2* indeed measures cardiac iron level.

Psychosocial and behavioral outcomes in children with sickle cell disease and their healthy siblings.

The current study aims to compare positive and negative measures of psychosocial functioning among children with sickle cell disease (SCD) and their healthy siblings. Participants were 41 African-American children with SCD, 97 healthy siblings, and their primary caregivers. Primary caregivers completed self-report questionnaires assessing child behavioral problems, while children with SCD and siblings completed self-report questionnaires assessing coping, self-efficacy, and perceived social support. No significant differences were noted between children with SCD and their siblings on all measures. Both groups reported self-efficacy and perceived social support within the normative range, and endorsed significantly greater use of Positive/Approach coping. In general, both groups of children do not have clinically significant behavioral problems. However, secondary exploratory analyses identified that a greater percentage of children from both groups scored above the established clinical cutoff on the behavioral summary scores. Number of visits to the emergency room was related to behavioral problems in children with SCD. While previous reports have been mixed in their findings that children with SCD are at greater risk for psychosocial and other behavioral problems, the current report finds that children with SCD and their healthy siblings endorse positive psychosocial functioning and as a group do not have clinically significant behavioral problems. Nonetheless, ongoing psychosocial evaluation for children receiving treatment for SCD is vital.

Detection and assessment of stroke in patients with sickle cell disease: neuropsychological functioning and magnetic resonance imaging.

Sickle cell disease (SCD) is associated with increased risk of stroke and cognitive impairment. This study describes a retrospective review of 65 patients who underwent routine neuropsychological testing and MRI during treatment at a comprehensive sickle cell center. It was hypothesized that (1) children with no evidence of CVA would perform lower than expected on cognitive tasks compared to population-based normative data, (2) children with strokes and children with silent infarcts would perform lower on cognitive tasks and motor skills as compared to patients with no evidence of CVA, and (3) children with evidence of silent infarcts would perform better than children with known overt strokes. This final hypothesis has not been studied previously, as children with known overt stroke and silent infarct were grouped together. Sixty-five children with SCD who were sent for routine neuropsychological testing and brain MRI were identified via retrospective chart review. Patients had been administered neuropsychological tests to assess cognitive, executive and motor function. Brain MRI was obtained from each patient and was analyzed for evidence of cerebrovascular accident (CVA). Based on MRI analysis, 27% of patients with SCD had experienced a stroke and 13% a silent infarct. The majority (59%) of patients diagnosed with stroke or infarct sustained cortical damage to the frontal lobe. Patients with SCD and no evidence of CVA functioned normally on tests of cognitive ability and achievement, but patients with CVA displayed impairments in cognitive function and comparatively lower scores on verbal and performance scales. Neuropsychological testing can identify impairments in patients with SCD with no known cerebrovascular accident. Investigations of neurocognitive functioning will help characterize patterns of deficits and can inform the ability to implement comprehensive care strategies for patients with SCD and cognitive impairment.

Outcomes of preimplantation genetic diagnosis therapy in treatment of beta-thalassemia: A retrospective analysis.

Thalassemia is one of the most common single-gene disorders that can be cured by hematopoietic stem cell transplantation (HCT) from a human leukocyte antigen (HLA)-identical sibling donor. In families that have an affected child, preimplantation genetic diagnosis (PGD) can be used to select an unaffected, HLA-identical embryo. In brief, this procedure requires in vitro fertilization, oocyte retrieval, fertilization, and blastomere biopsy for identification of unaffected HLA-identical embryos. After delivery, umbilical cord blood from the sibling donor is collected for HCT. The objective of this study was to determine the outcomes of families using PGD therapy for cure of beta-thalassemia and to review the limitations of PGD therapy. Families affected with beta-thalassemia who attempted PGD therapy were retrospectively identified and reviewed for indication, attempted cycles, successful pregnancy, and transplantation outcomes. Eight identified families affected by thalassemia underwent PGD. The diagnosis of their affected children included six cases of beta-thalassemia major and two cases of transfusion-dependent hemoglobin E-beta-thalassemia patients. A total of 14 cycles of PGD were attempted, ranging from one to four attempts per family. Following successful identification of HLA-identical cells, two pregnancies occurred, of which one resulted in engraftment of a beta-thalassemia child. PGD therapy offers the possibility of recruiting a suitable donor for HCT, yet is limited by financial cost due to labor-intensive techniques, low probability of obtaining an HLA-matched unaffected embryo, variable implantation capacity, and significant emotional impact. Improvements in PGD therapy's efficacy and cost will make this a more viable option for affected families.

Using quality improvement strategies to enhance pediatric pain assessment.

OBJECTIVE: To evaluate the impact of a quality improvement approach to implementing developmentally appropriate pain assessment guidelines for pediatric inpatients. Patient and staff satisfaction with pain assessment and management, and staff documentation were evaluated one year following the implementation of the revised pain assessment guidelines. DESIGN: Quasi-experimental design. SETTING: The pediatric hematology/oncology unit of a regional children's hospital. Study participants. A convenience sample of 36 children and 68 staff at time 1 (TI) and 49 children and 82 staff at time 2 (T2). INTERVENTIONS: Staff were educated on the use of pediatric pain assessment tools and a standardized pain assessment protocol was put into practice. Children or their primary caregivers were interviewed, using a questionnaire modified from the American Pain Society quality assurance guidelines, regarding their experiences with pain assessment and management on the unit at T1, just prior to the staff education, and one year later at T2. Multidisciplinary unit staff completed a parallel questionnaire at T1 and T2. MAIN OUTCOME MEASURES: Patient and staff satisfaction with pain assessment and management, and chart audit of compliance with pain assessment documentation. RESULTS: Patients, family members, and staff reported increased pain assessment, improved staff responsiveness to patients' pain and greater satisfaction with assessment tools between TI and T2. Increased compliance with the assessment guidelines was confirmed by chart audit. CONCLUSIONS: Improved pain assessment and management practices with resultant increase in patient and staff satisfaction can be achieved and sustained over time using quality improvement strategies.

Assessment of sickle cell pain in children and young adults using the adolescent pediatric pain tool.

The objectives of this study were to describe and compare the characteristics of pain experienced by children and young adults with sickle cell disease (SCD) in inpatient and outpatient settings. The Adolescent Pediatric Pain Tool (APPT), a multidimensional self-report pain assessment, was completed by African American children and young adults (mean age 15.39 +/- 4.32) with SCD during a clinic visit (n = 52), day hospital visit (n = 29), or during the first 24 hours of an inpatient stay (n = 72). Multiple linear regression revealed that pain intensity, number of body areas with pain, and the quality of pain were related to age, sex, and care setting. Pain intensity, location, and quality were of greater magnitude than previous reports of early postoperative pain in children. Examining the specific dimensions of pain intensity, location, and quality and the influencing factors of age, sex, and care setting may lead to more effective treatments for SCD pain.