Reperfusion injury pathophysiology in sickle transgenic mice.
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Reperfusion of tissues after interruption of their vascular supply causes free-radical generation that leads to tissue damage, a scenario referred to as "reperfusion injury." Because sickle disease involves repeated transient ischemic episodes, we sought evidence for excessive free-radical generation in sickle transgenic mice. Compared with normal mice, sickle mice at ambient air had a higher ethane excretion (marker of lipid peroxidation) and greater conversion of salicylic acid to 2,3-dihydroxybenzoic acid (marker of hydroxyl radical generation). During hypoxia (11% O(2)), only sickle mice converted tissue xanthine dehydrogenase to oxidase. Only the sickle mice exhibited a further increase in ethane excretion during restitution of normal oxygen tension after 2 hours of hypoxia. Only the sickle mice showed abnormal activation of nuclear factor-kappaB after exposure to hypoxia-reoxygenation. Allopurinol, a potential therapeutic agent, decreased ethane excretion in the sickle mice. Thus, sickle transgenic mice exhibit biochemical footprints consistent with excessive free-radical generation even at ambient air and following a transient induction of enhanced sickling. We suggest that reperfusion injury physiology may contribute to the evolution of the chronic organ damage characteristic of sickle cell disease. If so, novel therapeutic approaches might be of value. (+info)
Doppler echocardiographic study in adolescents and young adults with sickle cell anemia.
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OBJECTIVE: Anatomical and functional assessment of the heart through Doppler and echocardiography in patients with cell anemia (SCA). METHODS: Twenty-five patients with SCA and ages ranging from 14 to 45 years were prospectively studied in a comparison with 25 healthy volunteers. All of them underwent clinical and laboratory evaluation and Doppler echocardiography as well. The measurements were converted into body surface indices. RESULTS: There were increases in all chamber diameters and left ventricle (LV) mass of the SCA patients. It was characterised an eccentric hypertrophy of the left ventricle. The preload was increased (left ventricle end-diastolic volume) and the afterload was decreased (diastolic blood pressure, peripheral vascular resistance and end-systolic parietal stress ESPS). The cardiac index was increased due to the stroke volume. The ejection fraction and the percentage of the systolic shortening, as well as the systolic time intervals of the LV were equivalent. The isovolumetric contraction period of the LV was increased. The mitral E-septum distance and the end-systolic volume index (ESVi) were increased. The ESPS/ESVi ratio,a loading independent parameter, was decreased in SCA, suggesting systolic dysfunction. No significant differences in the diastolic function or in the pulmonary pressure occurred. CONCLUSION: Chamber dilations, eccentric hypertrophy and systolic dysfunction confirm the evidence of the literature in characterizing a sickle cell anemia cardiomyopathy. (+info)
Fetal hemoglobin in sickle cell disease: relationship to erythrocyte phosphatidylserine exposure and coagulation activation.
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In sickle cell disease (SCD), loss of erythrocyte membrane phospholipid asymmetry occurs with the exposure of phosphatidylserine (PS), which provides a docking site for coagulation proteins. In vivo sickling/desickling, with resulting red cell membrane changes and microvesicle formation, appears to be one of the factors responsible for PS exposure. We evaluated children with SCD homozygous for sickle hemoglobin (SS disease) and controls (n = 65) and demonstrate that high levels of fetal hemoglobin (assessed as F cells) are associated with decreased microvesicle formation, PS exposure, and thrombin generation. F cells correlated inversely with both microvesicles and PS positivity (P <.000001) in SS disease. Multiple regression analyses using various hematologic parameters as independent variables, and either microvesicles or PS positivity as the dependent variable, showed a strong relationship only with F cells. Additionally, plasma prothrombin fragment F1.2 levels (a marker for thrombin generation) correlated with both PS positivity (P <.001) and F cells (P <.01). An F-cell level of approximately 70% was associated with normal levels of prothrombin fragment F1.2 and with microvesicle formation indistinguishable from control values. We suggest that the use of such surrogate biologic markers in conjunction with F-cell numbers may provide valuable insights into the biology and consequences of in vivo sickling. (+info)
Hypoxia/reoxygenation causes inflammatory response in transgenic sickle mice but not in normal mice.
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In sickle cell anemia, the initiation, progression, and resolution of a vasoocclusive episode may present features of ischemia-reperfusion injury, with recurrent episodes of ischemia/hypoxia and reoxygenation promoting inflammation. Here, we have tested the hypothesis that hypoxia/reoxygenation triggers inflammation in the transgenic sickle mouse. In these mice, even at ambient air, peripheral leukocyte counts are elevated by 1.7-fold and neutrophil counts by almost 3-fold. Two hours of hypoxia, followed by reoxygenation, induced a greater than normal rolling flux and adhesion of leukocytes in these mice, but no leukocyte extravasation. When 3 hours of hypoxia was followed by reoxygenation, sickle mice, but not normal mice, showed a distinct inflammatory response characterized by an increased number of adherent and emigrated leukocytes. Because these events, which are exaggerated in sickle mice, are not seen in response to hypoxia alone, we conclude that they represent a form of reperfusion injury. Studies using an H(2)O(2)-sensitive probe revealed clear evidence of oxidant production in vascular endothelial cells after hypoxia/reoxygenation in sickle mice. Infusion of an anti-P-selectin antibody, but not an anti-E-selectin antibody, completely inhibited this inflammatory response and significantly increased wall shear rates. These findings suggest that leukocyte-endothelium interaction contribute to vasoocclusive events in the sickle mice and perhaps in human sickle disease. (+info)
Effect of active prenatal management on pregnancy outcome in sickle cell disease in an African setting.
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Sickle cell disease (SCD) is associated with an increased risk of medical complications during pregnancy. In sub-Saharan Africa, fetal and maternal mortality rates are particularly high. This study evaluated the effect of an active prenatal management program on pregnancy outcome in patients with SCD in an African setting. Pregnant women with SCD attending the National Teaching Hospital in Cotonou (The Republic of Benin, West Africa) were recruited before the 28th week of gestation. Management was based on providing information and education about SCD and improving nutritional status, malaria prevention, early detection of bacterial infections, and restricted use of blood transfusion. Maternal and fetal mortality rates and SCD-related morbidity were the principal variables assessed. One hundred and eight patients (42 SS and 66 SC) with 111 fetuses were included in the study. Thirteen fetal deaths (from 9 SS and 4 SC mothers) were recorded and 2 deaths of SC mothers. The maternal mortality rate of 1.8% was comparable with the overall maternal mortality rate for this maternity unit (1.2%). Few SCD-related events were recorded. Plasmodium falciparum malaria infection was the major cause of morbidity. Sixty-three patients (19 SS and 44 SC) successfully completed their pregnancy (58.3%) without requiring transfusion. Providing pregnant SCD patients with relevant medical care based on simple cost-effective approaches can have a positive impact on SCD-associated morbidity and mortality in an otherwise difficult setting in Africa. (Blood. 2000;96:1685-1689) (+info)
Depression and functioning in relation to health care use in sickle cell disease.
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The purpose of the current study was to investigate depression and health care use in patients with sickle cell disease (SCD). Forty-four adults with SCD were interviewed and data from 43 participants, both with (n = 11) and without (n = 32) depression, were used for further analyses. Data from one potential subject were excluded on the basis of diagnosis. The full evaluation included the Structured Clinical Interview for DSM-III-R Disorders (SCID) and the Center for Epidemiologic Studies--Depression Scale (CES-D), as well as measures of psychosocial and behavioral functioning. Good between-instrument agreement was found between the self-report and interview-based measures of depression. However, the functioning data did not entirely support the use of a more stringent cutoff score on the CES-D. Findings suggest that the purpose of the evaluation should be factored into the decision-making process when determining which cutoff score should be utilized (i.e. what is the cost-benefit ratio for false-positives vs. false-negatives). A series of hierarchical regression analyses supported the finding that disease severity alone does not explain the level of functioning displayed by patients. More importantly, the patient's perceived functioning was the best indicator of health care use within a 1-year period. Furthermore, specific interventions that target negative thinking and distorted cognitions, as well as provide psychoeducation, such as cognitive-behavioral therapy, need to be further explored within this population. (+info)
Serum opsonic activity in infants with sickle-cell disease immunized with pneumococcal polysaccharide protein conjugate vaccine. The Pneumococcal Conjugate Vaccine Study Group.
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Pneumococcal infections are an important cause of morbidity and mortality in children with sickle-cell disease (SCD). Pneumococcal conjugate vaccines (PCVs) are immunogenic in healthy infants <2 years of age but have not been evaluated in young children with SCD. Infants with SCD were immunized with a 7-valent PCV (Wyeth-Lederle Vaccines & Pediatrics) at 2, 4, and 6 months of age. A booster dose of 23-valent pneumococcal polysaccharide vaccine (PPV; Pnu-Immune) was administered at 24 months of age. Antipneumococcal type 6B and 14 serum opsonic activity was measured to assess the biologic function of the antibody. Following the administration of three doses of PCV, opsonic activity against serotype 6B increased from 4. 8% at 2 months to 33.5% at 7 months, with a subsequent decline to 8.1% at 12 months and 7.5% at 24 months and with an increase to 30.7% at 25 months after administration of a booster dose of PPV. Similar trends were seen with serotype 14 (opsonic activities were 9.4% at 2 months, 24.9% at 7 months, 16.5% at 12 months, and 12.6% at 24 months, and the opsonic activity was 27.3% 1 month after the administration of PPV). Serum opsonic activity correlated with antibody levels for both serotypes. PCV induces serum opsonic activity in infants with SCD. Antipneumococcal serum opsonic activity correlates with antibody levels. (+info)
Fludarabine-based conditioning for allogeneic transplantation in adults with sickle cell disease.
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Although allogeneic transplantation can be curative for patients with sickle cell disease, the toxicity of conditioning regimens has precluded its use in adults with significant end-organ damage. Newer conditioning regimens have been developed that are less toxic and that may broaden the applicability of allogeneic transplantation in this disorder. We report two adults with end-stage sickle cell disease, who underwent allogeneic transplantation from an HLA-identical sibling donor after conditioning with fludarabine/melphalan and ATG. Both patients had been extensively transfused and one had multiple RBC antibodies. One of the patients also had end-stage renal disease, and was dialysis dependent. Engraftment occurred promptly in both patients. Both achieved 100% donor chimerism and both were free of pain crises after transplant. The first patient died of a respiratory failure related to chronic graft-versus-host disease (GVHD) on day 335 after transplantation. The second patient developed severe gastro-intestinal GVHD and TTP and died on day 147 after transplantation. Conditioning with fludarabine/melphalan and ATG followed by allogeneic stem cell transplantation resulted in prompt and reliable engraftment in adults with end-stage sickle cell disease. The incidence of severe GVHD was unacceptably high and may be related to the ethnicity of the patients or to the inflammatory state associated with pre-existing sickle cell disease. (+info)