Fetal hemoglobin in sickle cell anemia: relationship to erythrocyte adhesion markers and adhesion.

To assess whether fetal hemoglobin (HbF) modulates the adhesion of sickle erythrocytes to endothelium, children with homozygous sickle cell anemia (SS disease) were studied, using this physiologically crucial period to evaluate the relationships between HbF and the major erythrocyte adhesion markers. The mean level of CD36(+) erythrocytes was 2.59% +/- 2.15% (+/- SD, n = 40) with an inverse relationship between CD36 positivity and F cells (R = -0.76, P < .000 00 002). In univariate analyses, significant correlations with various hematologic parameters and age were noted. Multiple regression analyses, however, revealed a relationship solely with F cells. Minimal levels of very late activation antigen-4(+) (VLA4(+)) erythrocytes (0.31% +/- 0.45%, n = 40) with relationships similar to those noted for CD36(+) cells were also observed. The subpopulation of strongly adhesive stress reticulocytes was further assessed, using CD71 as their marker. The mean level of CD71(+) erythrocytes was 5.81% +/- 4.21%, with statistical correlates in univariate and multivariate analyses similar to those discussed above. When adhesion ratios were evaluated, inverse correlations were noted between basal and plasma-induced adhesion and F-cell numbers (R = -0.54, P < .0005; R = -0.53, P < .0006, n = 39). In addition, in analyses where basal or plasma-induced adhesion was the dependent variable and the independent variables included F cells and the various adhesion-related parameters, significant relationships solely with F cells were noted. The results demonstrate that SS patients with higher levels of F cells have concomitant decreases in the numbers of CD36(+), VLA4(+), and CD71(+) erythrocytes and that these findings translate into less adherent erythrocytes. These findings extend knowledge regarding the protective effects of HbF in the pathophysiology of sickle cell disease.

Splenic arteries and veins in pediatric sickle cell disease.

The goal of this study was to verify the existence and prevalence of large vessel lesions outside the central nervous system in young patients with sickle cell disease. Thus, 17 spleens resected because of episodes of sequestration or infarction and 41 controls were studied. Anomalies of arteries and veins were detected in all spleens from sickle cell disease patients, but no definite correlation with age, sex, type of sickle hemoglobin, or frequency of sequestration episodes could be established. The most consistent lesions were intimal proliferation affecting large arteries and veins, reduplication of the internal elastic lamina of large arteries, and a lesion not previously documented in this condition, that of subendothelial infiltration of the large veins by activated T cells. Endotheliitis showing some similarity with the one seen in sickle cell disease spleens was noted in 5 of 41 spleens of patients who did not suffer from sickle cell disease. However, when present it was usually mild. Very limited damage to the arterial elastica was noted in only 1 of the 41 controls. Minimal endothelial proliferation was seen in 2 of 41 controls.

Mechanisms of nocturnal oxyhemoglobin desaturation in children and adolescents with sickle cell disease.

Oxyhemoglobin desaturation in patients with sickle cell disease has been proposed as a possible mechanism in the initiaton of vasco-occlusive pain crises. Nocturnal oxyhemoglobin desaturation (NOD) has been described with a prevalence of up to 40% in children and adolescents with sickle cell disease. The objective of this study was to evaluate the mechanisms of nocturnal oxyhemoglobin desaturation in sickle cell disease and determine the role of obstructive sleep apnea. We performed 16-channel polysomnograms and pulmonary function testing in 20 patients with sickle cell disease (ages 7-21 years) who had documented desaturation on home oximetry studies. The median saturation awake was 94% (quartile range, 88-95). Median saturation during REM sleep was 93.5% (88-95) and during non-REM sleep 93.5% (87.5-95). The median respiratory disturbance index was low (1.35 quartile range, 0.25-2.85). Twelve patients had no obstructive apnea recorded, while 3 patients had a total of 9 or 10 episodes during the entire study. The median snoring time was 5. 65% of total sleep time (quartile range, 1.35-22.65). There was no correlation between number of obstructive apneas and mean sleeping saturation (r = 0.012, p = 0.95). There was no correlation between pulmonary function data and prevalence of NOD. There was a strong, positive correlation between sleeping and awake saturation (r = 0.96, p < 0.001). We conclude that while nocturnal oxyhemoglobin desaturation may be common in children and adolescents with sickle cell disease, upper airway obstruction does not appear to play an important role in its genesis.

Measurement of hemoglobin saturation by oxygen in children and adolescents with sickle cell disease.

Pulse oximetry is a noninvasive method of measuring oxyhemoglobin saturation. The validity of pulse oximetry in sickle cell disease (SCD) has been questioned. We evaluated pulse oximetry, arterial blood gas analysis, and co-oximetry in patients with SCD, and we assessed the effect of dyshemoglobin and altered blood-oxygen affinity on their accuracy. Sixteen patients with SCD aged 7-21 years had arterial and venous blood drawn and transcutaneous pulse oximetry performed. Oxyhemoglobin dissociation curves were plotted from the venous blood of 15 patients. Oxyhemoglobin saturation estimated by arterial blood gas analysis (SaO(2)) and measured by pulse oximetry (SpO(2)) were both higher than the saturation by co-oximetry (FO(2)Hb) (mean +/- SD = 96.3 +/- 1.6%, 94 +/- 3.1%, and 89.1 +/- 3.8%, respectively). There was a significant, positive correlation between SpO(2) and FO(2)Hb (r = 0.7, P = 0.002). The patients had elevated levels of methemoglobin (MetHb) and carboxyhemoglobin (COHb) (2.3 +/- 1.4% and 4.7 +/- 1.3%, respectively). The oxyhemoglobin dissociation curves were frequently shifted to the right with oxygen tensions elevated when hemoglobin was 50% saturated with oxygen (P(50)) (32.5 +/- 4.5 mm Hg). There was a strong correlation between the amounts of dyshemoglobin (MetHb + COHb) and the difference between SaO(2) and FO(2)Hb (r = 0.7, P = 0.002). There was no correlation between the difference between SaO(2) and FO(2)Hb and the P(50) (r = 0.27, P = 0.33) There was also a strong positive correlation between SaO(2)-SpO(2) and dyshemoglobin fraction (r = 0.77, P = 0.001). We conclude that pulse oximetry and arterial blood gas analysis overestimate oxygen saturation when compared to co-oximetry, but that SpO(2) is consistently closer than SaO(2) to FO(2)Hb. SpO(2) is partially affected by MetHb and COHb. The discrepancy between SaO(2) and FO(2)Hb is due to the presence of dyshemoglobin and a shifted oxyhemoglobin dissociation curve, but the effect from dyshemoglobin predominates.

Self-hypnosis training as an adjunctive treatment in the management of pain associated with sickle cell disease.

A cohort of patients with sickle cell disease, consisting of children, adolescents, and adults, who reported experiencing three or more episodes of vaso-occlusive pain the preceding year, were enrolled in a prospective two-period treatment protocol. Following a 4-month conventional treatment baseline phase, a supplemental cognitive-behavioral pain management program that centered on self-hypnosis was implemented over the next 18 months. Frequency of self-hypnosis group straining sessions began at once per week for the first 6 months, became biweekly for the next 6 months, and finally occurred once every third week for the remaining 6 months. Results indicate that the self-hypnosis intervention was associated with a significant reduction in pain days. Both the proportion of "bad sleep" nights and the use of pain medications also decreased significantly during the self-hypnosis treatment phase. However, participants continued to report disturbed sleep and to require medications on those days during which they did experience pain. Findings further suggest that the overall reduction in pain frequency was due to the elimination of less severe episodes of pain. Non-specific factors may have contributed to the efficacy of treatment. Nevertheless, the program clearly demonstrates that an adjunctive behavioral treatment for sickle cell pain, involving patient self-management and regular contact with a medical self-hypnosis team, can be beneficial in reducing recurrent, unpredictable episodes of pain in a patient population for whom few safe, cost-effective medical alternatives exist.

Airway hyperreactivity in children with sickle cell disease.

Progressive restrictive defect with increasing age, obstructive lung disease, and bronchodilator responsiveness have been reported in sickle cell disease (SCD). Because airway hyperreactivity (AHR) can be underestimated when assessed by bronchodilator responsiveness in patients with normal baseline lung function, the aim of this study was to investigate the prevalence of AHR in SCD by cold-air bronchial provocation testing, and to assess whether AHR can be present in symptom-free patients with SCD. Forty patients aged 6 to 19 years (mean, 10.7 years +/- 3.5 SD) performed pulmonary function tests. Eighteen were known to have a history of reactive airway disease (RAD group), and 22 had no known history of RAD (non-RAD group). A control group, aged 6 to 7 years (mean, 10.5 +/- 3.1 years), consisted of 10 siblings of the non-RAD SCD group. There were no significant differences in age and height among the groups. If the forced expiratory volume in 1 second (FEV1) was greater than 70%, cold air challenge (CACh) was performed; if the FEV1 was less than 70%, aerosolized bronchodilator therapy was given. A decrease in FEV1 of more than 10% after CACh or an increase in FEV1 of 12% or greater after bronchodilator inhalation was considered evidence of AHR. In the RAD group, the total lung capacity was 88.9% +/- 14.0% of race-corrected predicted values, the forced vital capacity was 91.2% +/- 12.6%, and FEV1 was 85.3% +/- 16.2%. The mean maximal percent fall in FEV1 after CACh (n = 13) was 18.5% +/- 9.6% and was greater than 10% in 11 of 13 patients. The mean increase in FEV1 after bronchodilator therapy (n = 5) was 11.5% +/- 8.3%, and it was greater than 12% in 4 of 5 patients. In the non-RAD group the baseline total lung capacity was 101.6% +/- 11.7%, forced vital capacity was 95.5% +/- 10.2%, and FEV1 was 93.3% +/- 13.2%. The mean maximal percent fall in FEV1 after CACh (n = 19) was 14.1% +/- 8.8% and was greater than 10% in 13 of 19 patients. The mean increase in FEV1 after bronchodilator therapy (n = 3) was 14.7% +/- 11.3%, and was 12% of greater in 1 of 3 patients. In the control group the baseline total lung capacity was 105.7% +/- 12.1%, forced vital capacity was 96.2% +/- 11.1%, and FEV1 was 92.9% +/- 10.3%. The mean maximal percent fall in FEV1 was 5.0% +/- 2.5%, and was greater than 10% in none of 10 patients. The prevalence of AHR in the control group, the RAD group, and the non-RAD group was zero, 83%, and 64%, respectively (p < 0.0001). The overall prevalence in the SCD group was 73%. We conclude that there is a high prevalence of AHR in children with SCD and that airway hyperreactivity may exist in patients with SCD even in the absence of the clinical symptoms of RAD. AHR may be a significant component of sickle cell lung disease.

High-dose cytosine arabinoside and fractionated total body irradiation as a preparative regimen for the treatment of children with acute lymphoblastic leukemia and Down syndrome by allogeneic bone marrow transplantation.

The early toxicity, incidence of graft-versus-host disease (GVHD) and long-term follow-up were evaluated in two children with Down syndrome (DS) treated for acute lymphoblastic leukemia (ALL) in second complete remission by HLA-matched sibling allogeneic bone marrow transplantation (BMT). Preparative conditioning therapy consisted of cytosine arabinoside (Ara-C) and fractionated total body irradiation (F-TBI) and GVHD prophylaxis of cyclosporin A. The conditioning regimen was well tolerated, the only acute complication being mild mucositis. Engraftment (polymorphonuclear cells >500/microliter) was documented by day +17 in both patients. One child remains in continuous complete remission, without medical problems, 60 months after BMT. The second patient died from complications associated with chronic GVHD 21 months following BMT. Ara-C and F-TBI is a well-tolerated preparative regimen for children with DS undergoing allogeneic BMT.

Arachidonic acid metabolites are involved in mediating red blood cell adherence to endothelium.

As an initial investigation into the possible role of endothelial cell (EC) lipoxygenase and cyclooxygenase metabolites in the adherence of red blood cells (RBCs) to ECs, we evaluated the effect of nordihydroguaiaretic acid, (NDGA; 10 mumols/L, BW755c (30 mumols/L), aspirin (100 mumols/L), and indomethacin (10 mumols/L) on RBC-EC adherence using a static incubation system and 51Cr-labeled RBCs. NDGA and 3-amino-L-[3'-(trifluoromethyl)phenyl]-2-pyrazoline inhibitors of both the lipoxygenase and cyclooxygenase pathways, significantly decreased basal adhesion of RBCs to fetal bovine aortic ECs, whereas aspirin and indomethacin, selective inhibitors of the cyclooxygenase pathway, stimulated the adherence process. The inhibitor effect appeared to be mediated via an effect on EC functions, since preincubation of ECs with NDGA, in contrast to RBC-NDGA preincubation, inhibited the adherence process. Because bovine aortic ECs generate mainly prostacyclin and 15-HETE from arachidonic acid (AA) via the cyclooxygenase and the lipoxygenase pathways respectively, the role of these products (100 pmol/L to 1 mumol/L) on the adhesive process was further assessed. 15-HETE potentiated basal adhesion of RBCs to bovine aortic ECs in a concentration-dependent manner, with maximal responses of approximately 50% to 150% over baseline noted at concentrations between 1 and 100 nmol/L 12-HETE, a structural isomer of 15-HETE and the major platelet lipoxygenase product, also stimulated RBC adherence. In contrast, prostacyclin (assessed using carbacyclin, a stable synthetic analog of prostacyclin with similar biologic properties) had no significant effect on this process. In further studies, we demonstrated that the 12-HETE-induced adherence of sickle RBCs was mediated via an up-regulation of the vitronectin receptor on bovine aortic endothelium. Because microvascular capillary endothelium is the surface most likely to encounter erythrocytes in vivo, we extended our studies to human retinal capillary ECs to assess the involvement of eicosanoids in sickle RBC-microvessel adhesion. As with bovine aortic ECs, aspirin stimulated and NDGA decreased the adherence of sickle RBCs to human retinal capillary endothelium. These microvascular ECs generated prostacyclin, HHT, 15-HETE, and 15-HPETE from endogenous AA. Although carbacyclin and HHT had no effect on the adherence process, both 15-HETE and 15-HPETE (10 pmol/L to 100 nmol/L) stimulated RBC adhesion to capillary endothelium. Our studies document a role for the lipoxygenase metabolites in modulating basal adhesion of RBCs to both macrovascular and microvascular endothelium; the major cyclooxygenase metabolites appear to play no role in this process.

Intravenous morphine pharmacokinetics in pediatric patients with sickle cell disease.

To examine the pharmacokinetics of parenteral opioids, such as morphine, in patients with sickle cell disease, we determined the plasma morphine clearances in 18 patients (aged 6 to 19 years) who were receiving continuous intravenous infusions, and the pharmacokinetics of morphine in an additional six patients after single intravenous doses. Plasma morphine clearances ranged from 6.2 to 59.1 ml min-1 kg-1 (35.5 +/- 12.4, mean +/- SD) during steady-state infusions. There was a negative correlation between clearance values and age over the age range studied (p = 0.013). A significant difference (p = 0.042) was also observed in clearance values between patients who had serious adverse symptoms (23.4 +/- 10.7 ml min-1 kg-1) and those who had less serious symptoms (36.3 +/- 6.4 ml min-1 kg-1) when morphine was given at high dosage rates (> or = 0.15 mg kg-1 hr-1). Pharmacokinetic modeling of plasma morphine concentrations adequately fit a two-compartment model with a short initial distribution phase (mean half-life = 4.5 minutes) and a rapid terminal elimination half-life (77.6 +/- 19.2 minutes). These findings suggest that considerable individualization of morphine dosing may be necessary to achieve optimal analgesia and minimal adverse effects in these patients.

Prenatally diagnosed non-immune hydrops caused by congenital transient leukaemia.

Congenital transient leukaemia (CTL) is a haematological disorder characterized by proliferation of myeloblasts within the bone marrow and peripheral blood of affected newborns. Infants with Down syndrome are most frequently affected and although the disorder can result in fetal death due to hydrops, it typically resolves spontaneously after birth. We present a case of prenatally diagnosed fetal hydrops accompanied by splenomegaly and an enlarged, echogenic liver in a fetus identified with CTL after birth.

1-Deamino-8 D-arginine vasopressin decreases the production of 13-hydroxyoctadecadienoic acid by endothelial cells.

1-Deamino-8 D-arginine vasopressin (DDAVP) has been used effectively to normalize the bleeding time in various hemostatic disorders. In von Willebrand disease the reduction in bleeding time is due to the preferential release of large multimers of von Willebrand factor from endothelial cells. However, since the bleeding time correction in patients with uremia and liver disease is independent of the release of von Willebrand antigen and activity, other mechanisms of action of DDAVP need to be considered. Endothelial cells generate several thromborepellant factors including 13-hydroxyoctadecadienoic acid (13-HODE), an inhibitor of platelet adhesion to subendothelium. Using cultured fetal bovine aortic endothelial cells (FBAECs), we have investigated whether DDAVP modulates the production of 13-HODE. We have demonstrated that 14C-linoleic acid labeled FBAECs release several oxygenated derivatives of linoleic acid following a 120 min incubation in the presence of serum. One of these products was identified by chromatographic procedures as 13-HODE. The production of 13-HODE was decreased significantly by DDAVP (1-100 ng/ml) with maximal reduction (approx. 25%) seen at 1 ng/ml of DDAVP. While vehicle treated control FBAECs generated 6780 +/- 690 cpm of 13-HODE per 10(6) cells (mean +/- SE, n = 8), DDAVP treated FBAECs produced 4950 +/- 310 (P < 0.01), 5390 +/- 390 (P < 0.01), and 5720 +/- 410 cpm (P < 0.05) of 13-HODE at 1, 10, and 100 ng/ml DDAVP respectively. Our findings of a decrease in 13-HODE would explain the previously observed morphologic changes of increased platelet adhesion to subendothelium following DDAVP infusion and contributes to our understanding of the mode of action of this therapeutic agent in hemostatic disorders.

Pain in children and adolescents with sickle cell disease: a descriptive study.

In sickle cell disease, vaso-occlusion in the small blood vessels leads to bone or joint pain which is variable in intensity and duration. An essential first step toward the development of specific treatment guidelines for such painful episodes in children and adolescents is the accurate evaluation of pain. The systematic assessment of vaso-occlusive pain is addressed through two separate studies. In the first, 35 pediatric sickle cell disease patients between 5 and 16 years of age were evaluated in an outpatient clinic with the Varni/Thompson Pediatric Pain Questionnaire. In the second, data were gathered over the course of hospitalizations for uncomplicated vaso-occlusive episodes in 17 adolescent patients. Results showed that this pain experience can be quantified, that vaso-occlusive pain spans a broad range of intensity levels, and that there are a number of socioemotional factors associated with the pain experience. Further research to systematically assess the psychometric properties of pain assessment instrument is recommended.

Clinical and laboratory study of two Caucasian families with hereditary pyropoikilocytosis and hereditary elliptocytosis.

Hereditary pyropoikilocytosis (HPP) is a severe, congenital hemolytic anemia occurring almost exclusively in black persons and characterized by extreme red blood cell anisopoikilocytosis. The authors report two unrelated white females with HPP. Both had severe hemolytic anemia at birth, red blood cell morphologic features characteristic for HPP, and increased thermal sensitivity of the red blood cells. Examination of the red blood cell membranes of both patients showed markedly unstable membrane skeletons when subjected to shear stress, spectrin dimer association defects with increased dimers, and partial spectrin deficiency. Limited tryptic digestion of the spectrin molecule from both patients yielded an abnormal pattern with a decrease in the normal 80,000-dalton alpha I domain and a concomitant increase of an abnormal 74,000-dalton peptide (Sp alpha 1/74). One parent and one sibling of one of the patients with HPP had hereditary elliptocytosis (HE) and the Sp alpha 1/74 defect. The other patient with HPP was different from others reported in that both parents were hematologically and biochemically normal. In addition, her daughter had HE and the Sp alpha 1/74 defect.

Association of red cell spherocytosis with deletion of the short arm of chromosome 8.

Congenital spherocytic anemia is a common disorder, but in most cases the nature of the underlying membrane lesion is unknown and the genetic defect has not yet been unequivocally mapped to a chromosome. We studied two dysmorphic siblings with neurologic findings and hemolytic anemia. Clinical and laboratory findings in these two siblings were consistent with the diagnosis of congenital spherocytosis whereas both parents and two unaffected siblings were normal. The two affected children had an abnormal chromosomal complement as a result of a deletion of the short arm of chromosome 8 [(46,XX,del(8)(p11.1p21.1)]. These results suggest that a gene whose deletion results in a congenital spherocytic anemia phenotype resides on this region on the short arm of chromosome 8.

Acute non-lymphoid leukemia.

Acute non-lymphoid leukemia is a group of hematologic neoplasms which have been the subject of intensive basic and clinical research. These studies have led to a better understanding of the genetic basis of leukemia and may ultimately help establish the molecular mechanisms of malignant transformation. They also have increased our understanding of myeloid differentiation. As a result of clinical trials, we can now induce a clinical remission in a large majority of patients with acute non-lymphoid leukemia. Future studies will attempt to lessen toxicity and to maximize the response rate. Many of these advances will come from improvements in supportive care given during the periods of therapy-related marrow aplasia. The role of intensive chemotherapy to prolong remission duration and to increase the usefulness of allogenic bone marrow transplantation will be clarified during the next several years.