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Increased in vivo production of thromboxane in patients with sickle cell disease is accompanied by an impairment of platelet functions to the thromboxane A2 agonist U46619.

Thrombosis represents an important cause of mortality in patients with sickle cell disease, in addition to the complications caused by the primary defect of inherited abnormal hemoglobin. To study the involvement of platelets in these complications, we assessed the biosynthesis of thromboxane A2 in samples from 49 patients with sickle cell disease and in 33 control subjects. The urinary excretion of the major arachidonic acid metabolite of platelet origin (11-dehydro-thromboxane B2) and of the vascular endothelial cell (2,3-dinor-6-ketoprostaglandin F1 alpha) were very significantly increased (p < 0.0002) in the patients. In a small group of patients (n = 14), we further investigated the ex vivo response of their platelets to U46619, a stable analogue of thromboxane A2. We observed decreased aggregation and [14C]serotonin release compared with control (p < 0.05); similarly, we found impaired p47 protein phosphorylation (p < 0.05). In contrast, platelets from these patients responded normally to thrombin (0.1 unit/mL). In vivo desensitization of platelets from these patients to thromboxane may constitute a form of regulation that may prevent the propagation of aggregation by this potent inducer, as has been hypothesized in in vitro studies. Our results may also provide a rationale for using antiplatelet drugs in the prophylaxis of thrombotic complications in sickle cell patients.

6-Ketoprostaglandin F1 alpha↗

Hereditary nonspherocytic hemolytic disease associated with an altered phospholipid composition of the erythrocytes.

A hemolytic disorder with mild hyperbilirubinemia and reticulocytosis of 6 to 15% was documented in eight members of a large family from the Dominican Republic and was presumed to be present in eight other members. The disorder appeared to be inherited as an autosomal dominant characteristic. Analysis of phospholipids by quantitative thinlayer chromatography revealed a distinct increase in phosphatidyl choline (lecithin) to 35.5 +/- SD 1.3% of the total (normal: 28.2 +/- 1.4%) in erythrocytes of affected members of the family, but not in the cells of unaffected relatives. The alteration appeared to constitute an absolute increase in lecithin content, rather than a decrease in other phospholipids. Erythrocytes from patients with other varieties of hereditary hemolytic disorders and comparable levels of reticulocytosis had normal phospholipid compositions. Plasma lipids of six affected members of the family were not unusual with respect to total lipid weight, total phospholipid, and cholesterol. Three patients with liver disease and jaundice were found to have marked increases in the lecithin content of the erythrocytes, but they also had extremely high plasma levels of total lipid, phospholipids, and cholesterol. Osmotic fragility of the erythrocytes of affected patients was decreased and the increase in fragility after incubation for 24 hr was less than that observed with normal erythrocytes. Autohemolysis after 48 hr was slightly increased and was corrected to nearly normal by the addition of glucose. The activities of 15 enzymes of the erythrocytes of the propositus were normal or elevated and the adenosine triphosphate content was normal. An abnormal hemoglobin could not be demonstrated. The life span of isologous erythrocytes in the propositus was reduced, but homologous erythrocytes survived normally.A causal relationship between the altered phospholipid composition and the hemolytic disorder has not been established.

Adenosine Triphosphate↗

Therapy with oral clotrimazole induces inhibition of the Gardos channel and reduction of erythrocyte dehydration in patients with sickle cell disease.

Pathologic water loss from sickle erythrocytes concentrates the abnormal hemoglobin and promotes sickling. The Ca2+-activated K+ channel (Gardos channel) contributes to this deleterious dehydration in vitro, and blockade of K+ and water loss via this channel could be a potential therapy in vivo. We treated five subjects who have sickle cell anemia with oral clotrimazole, a specific Gardos channel inhibitor. Patients were started on a dose of 10 mg clotrimazole/kg/d for one week. Protocol design allowed the daily dose to be escalated by 10 mg/kg each week until significant changes in erythrocyte density and K+ transport were achieved. Blood was sampled three times a week for hematological and chemical assays, erythrocyte density, cation content, and K+ transport. At dosages of 20 mg clotrimazole/kg/d, all subjects showed Gardos channel inhibition, reduced erythrocyte dehydration, increased cell K+ content, and somewhat increased hemoglobin levels. Adverse effects were limited to mild/moderate dysuria in all subjects, and a reversible increase in plasma alanine transaminase and aspartic transaminase levels in two subjects treated with 30 mg clotrimazole/kg/d. This is the first in vivo evidence that the Gardos channel causes dehydration of sickle erythrocytes, and that its pharmacologic inhibition provides a realistic antisickling strategy.

Administration, Oral↗

Leukocyte-endothelial interaction is augmented by high glucose concentrations and hyperglycemia in a NF-kB-dependent fashion.

We addressed the role of hyperglycemia in leukocyte-endothelium interaction under flow conditions by exposing human umbilical vein endothelial cells for 24 h to normal (5 mM), high concentration of glucose (30 mM), advanced glycosylation end product-albumin (100 microg/ml), or hyperglycemic (174-316 mg/dl) sera from patients with diabetes and abnormal hemoglobin A1c (8.1+/-1.4%). At the end of incubation endothelial cells were perfused with total leukocyte suspension in a parallel plate flow chamber under laminar flow (1.5 dyn/cm2). Rolling and adherent cells were evaluated by digital image processing. Results showed that 30 mM glucose significantly (P < 0. 01) increased the number of adherent leukocytes to endothelial cells in respect to control (5 mM glucose; 151+/-19 versus 33+/-8 cells/mm2). A similar response was induced by endothelial stimulation with IL-1beta, here used as positive control (195+/-20 cells/mm2). The number of rolling cells on endothelial surface was not affected by high glucose level. Stable adhesion of leukocytes to glucose-treated as well as to IL-1beta-stimulated endothelial cells was preceded by short interaction of leukocytes with the endothelial surface. The distance travelled by leukocytes before arrest on 30 mM glucose, or on IL-1beta-treated endothelial cells, was significantly (P < 0.01) higher than that observed for leukocytes adhering on control endothelium (30 mM glucose: 76.7+/-3.5; IL1beta: 69.7+/-4 versus 5 mM glucose: 21.5+/-5 microm). Functional blocking of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1 on endothelial cells with the corresponding mouse mAb significantly inhibited glucose-induced increase in leukocyte adhesion (67+/-16, 83+/-12, 62+/-8 versus 144+/-21 cells/ mm2). Confocal fluorescence microscopy studies showed that 30 mM glucose induced an increase in endothelial surface expression of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1. Electrophoretic mobility shift assay of nuclear extracts of human umbilical vein endothelial cells (HUVEC) exposed for 1 h to 30 mM glucose revealed an intense NF-kB activation. Treatment of HUVEC exposed to high glucose with the NF-kB inhibitors pyrrolidinedithiocarbamate (100 microM) and tosyl-phe-chloromethylketone (25 microM) significantly reduced (P < 0.05) leukocyte adhesion in respect to HUVEC treated with glucose alone. A significant (P < 0.01) inhibitory effect on glucose-induced leukocyte adhesion was observed after blocking protein kinase C activity with staurosporine (5 nM). When HUVEC were treated with specific antisense oligodesoxynucleotides against PKCalpha and PKCepsilon isoforms before the addition of 30 mM glucose, a significant (P < 0.05) reduction in the adhesion was also seen. Advanced glycosylation end product-albumin significantly increased the number of adhering leukocytes in respect to native albumin used as control (110+/-16 versus 66+/-7, P < 0.01). Sera from diabetic patients significantly (P < 0.01) enhanced leukocyte adhesion as compared with controls, despite normal levels of IL-1beta and TNFalpha in these sera. These data indicate that high glucose concentration and hyperglycemia promote leukocyte adhesion to the endothelium through upregulation of cell surface expression of adhesive proteins, possibly depending on NF-kB activation.

Cell Adhesion↗

A brief review of the pathophysiology, associated pain, and psychosocial issues in sickle cell disease.

Sickle cell disease (SCD) is the most common genetic disorder of the blood. The disease produces significantly abnormal hemoglobin (Hgb) molecules in red blood cells (RBCs). The sickling of RBCs occurs when partially or totally deoxygenated Hgb molecules distort their normal disk shape, producing stiff, sticky, sickle-shaped cells that obstruct small blood vessels and produce vasoocclusion as well as the disruption of oxygen to body tissues. Because tissue damage can occur at multiple foci, patients with SCD are at risk for other medical complications including, but not limited to, delayed growth and sexual maturation; acute and chronic pulmonary dysfunction; stroke; aseptic necrosis of the hip, shoulders, or both; sickle cell retinopathy; dermal ulcers; and severe chronic pain. The chronicity of the illness combined with frequent hospitalizations for pain and other medical management can contribute significantly to impaired psychosocial functioning, altered intra- and interpersonal relationships, and reduced quality of life. Unlike previous qualitative reviews of SCD, this article describes the relevant clinical and research data on the relation between psychosocial functioning and SCD in adult and child populations. The authors discuss the significant role of psychosocial issues in the trajectory and management of the disease and conclude that understanding the pathophysiology of SCD without thoroughly understanding the equally important psychosocial influences is misunderstanding SCD.

Adolescent↗

Fragmentation hemolysis in a patient with hypertrophic obstructive cardiomyopathy and mitral valve prolapse.

We encountered a 65-year-old female with hypertrophic obstructive cardiomyopathy and mitral valve prolapse who had infective endocarditis and hemolytic anemia. The infecting organism of endocarditis was group A streptococci. With regard to the etiology of the hemolytic anemia, fragmentation hemolysis was considered because fragmented red cells and elevated lactic dehydrogenase were observed. Haptoglobin was markedly decreased. Coombs' test, Ham's test and abnormal hemoglobin were negative. She had not had a hemolytic attack in the past. Ultrasonic cardiography showed asymmetrical septal hypertrophy, mitral valve prolapse and 285 mmHg of calculated pressure gradient in the left ventricle. Cardiac catheterization showed 115 mmHg of left intraventricular pressure gradient and mitral regurgitation (grade 2). Hemolysis was slightly improved after treatment with propranolol. Thus, fragmentation of the normal red cells seemed to be due to shear stress.

Aged↗

Red cell genetic abnormalities, beta-globin gene haplotypes, and APOB polymorphism in the Great Andamanese, a primitive Negrito tribe of Andaman and Nicobar Islands, India.

The Great Andamanese are a primitive Negrito tribe of the Andaman and Nicobar Islands, India, with a total population of 37. We studied 29 individuals from eight families from this population for abnormal hemoglobins, G6PD deficiency, DNA haplotypes, and apolipoprotein B (APOB, gene) polymorphism. Hb E was detected in five individuals, the prevalence of Hb E heterozygotes being 14.3%. One individual had beta-thalassemia trait. One female was G6PD deficient and showed the G6PD Orissa mutation. Haplotype analysis of the beta-globin gene cluster showed that the betaE chromosomes were linked to two haplotypes (- - - - - + + and + + - + + + +) representing the framework 1 gene, whereas the betaA chromosomes showed eight different haplotypic patterns corresponding to framework 1 and 3 genes. APOB polymorphism analysis showed that the 631-base-pair (bp) allele was the predominant one with a high homozygosity rate, which could be due to the higher rate of inbreeding in this isolated group. The presence of Hb E and our findings on haplotype analysis supports the hypothesis that the Great Andamanese are reasonably believed to be the surviving representatives of the Negrito race that once flourished in the entire Southeast Asian region in ancient times.

Adolescent↗

[Screening for hemoglobinopathies in blood donors from Caxias do Sul, Rio Grande do Sul, Brazil: prevalence in an Italian colony].

The high prevalence of beta thalassemia among Italians and their participation in the ethnic formation of Caxias do Sul, Rio Grande do Sul State, Brazil, and neighboring cities prompted us to investigate hemoglobinopathies in 608 blood donors at the Caxias do Sul Regional Blood Center. Despite the ethnic influence, abnormal hemoglobin levels were found in only 1.81% of the donors (0.16% Hb AC, 0.99% Hb AS, and 0.66% Hb AH), similar to the levels observed in a study on qualitative disorders conducted in the rural area of Rio Grande do Sul. In our setting, the most commonly used screening tests for thalassemia, combined with DNA sequencing, were unable to detect quantitative hemoglobin synthesis disorders. This may be attributable to still-unknown genetic disorders, technical limitations, or simply to miscegenation.

Adolescent↗

[Erythrocyte defects and parasitemia density in patients with Plasmodium falciparum malaria in Buenaventura, Colombia].

OBJECTIVES: To determine the prevalence of some erythrocyte defects and to evaluate the relation that that has with parasitemia density in individuals diagnosed with Plasmodium falciparum malaria in a population in the Pacific coastal region of Colombia. METHODS: This prevalence study was carried out with 242 persons with P. falciparum malaria who had gone for consultation at the Program of Tropical Diseases diagnostic center in the city of Buenaventura, Colombia. The parasitemia levels were measured, and also determined was the presence of congenital erythrocyte defects (glucose-6-phosphate dehydrogenase (G6PD) deficiency, abnormal hemoglobins, and thalassemias) and of other factors possibly related to parasitemia levels. RESULTS: The prevalence of erythrocyte defects was 26.4% (95% confidence interval, 21.0%-32.5%), which was similar to what had been found in previous studies in the same area of Colombia. In the multiple regression models, individuals with sickle cell anemia or a complete deficiency of G6PD had a lower density of parasitemia than did persons without any erythrocyte defect. After adjusting for other variables of interest, the risk of high parasitemias was lower in persons with sickle cell anemia (odds ratio = 0.30) and individuals with a complete deficiency of G6PD (odds ratio = 0.72). CONCLUSIONS: Our results confirm the high prevalence of erythrocyte defects in Colombia's Pacific coastal region, in a population with ethnic characteristics that are similar to those of some populations in West Africa. Our results also lend support for the existence of innate resistance to malaria among carriers of hemoglobin AS and in persons with G6PD deficiency.

Adult↗

Application of an automatic oxygenation technique to analysis of oxygen equilibrium curves for hemoglobinopathic red cells and functional screening of clinically important hemoglobinopathies.

The automatic oxygenation technique of Imai et al (Biochimica Biophysica Acta, 200:189--196, 1970) was slightly modified and applied to the study of oxygen equilibrium curves of dilute, red-cell suspensions from normal subjects and individuals with hemoglobinopathies, enzymopathies, and other hematologic disorders. The p50 values of non-smoking, normal adults were 25.9 +/- 0.6 mm Hg at pH 7.4 and 37 degrees C, and corresponded to the values for whole blood reported in the literature. The oxygen equilibrium curves of suspensions from subjects with enzymopathies revealed shifts in position which are thought to be due to alterations in the concentration of 2,3-DPG of the red cells. Abnormalities in shape of the equilibrium curves were observed only for the hemoglobinopathic red cells, and could best be illustrated by the abnormally low Hill's exponent (n*). Analyses of the n* values of 34 patients with various red-cell disorders of unknown causes led to the identification of ten cases showing low values. In five of the ten patients, the presence of an abnormal hemoglobin was confirmed using column chromatography on Amberlite CG--50. These results point to the usefulness of the Hill Plot analysis of red-cell oxygen dissociation curves in functional screening for clinically important hemoglobinopathies.

Erythrocytes↗

Hb F-Sassari: a novel G gamma variant with a threonine residue at position gamma 75, characterized by mass spectrometric techniques.

The cord blood sample of a Caucasian newborn contained about 40% of an abnormal fetal hemoglobin. The mutated gamma chain was isolated using reversed phase high performance liquid chromatography and characterized by means of electrospray and fast atom bombardment mass spectrometric techniques as a G gamma-globin variant with an Ile-->Thr substitution at position gamma 75. The variant chain shows the same structure as the previously described Hb F-Charlotte that was demonstrated to be an A gamma variant with an Ile-->Thr substitution at position gamma 75 and an additional Ala-->Gly substitution at gamma 136.

Chromatography, High Pressure Liquid↗

Mild thalassemia intermedia resulting from a new insertion/frameshift mutation in the beta-globin gene.

Hematological investigation of an antenatal patient led to the identification of a new beta-thalassemia mutation involving the net insertion of eight nucleotides into exon 2 of the beta-globin gene. As a result of the shift in the protein reading frame, this gene codes for an elongated beta-globin chain (159 amino acids) with an abnormal amino acid sequence beyond residue beta 99. There is no evidence of any abnormal hemoglobin in the circulation. The patient has a mild form of beta-thalassemia intermedia with moderate anemia, evidence of iron overload, severe red cell morphological changes, a significant reticulocytosis, and a marked increase in the proportion of fetal hemoglobin.

Adult↗

Pulse oximetry: application in the pediatric and neonatal critical care unit.

The use of pulse oximetry in the pediatric and neonatal intensive care units has grown tremendously in recent years. Opinions about this growth are divergent. Arriving at a generalized statement about the accuracy of pulse oximeters is difficult, but it has generally been found to be acceptably accurate in most patient populations under most conditions. However, there are limitations to its application. Pulse oximetry accuracy can be adversely affected by elevated levels of certain abnormal hemoglobin varieties as well as motion artifact and low peripheral perfusion. Some authors suggest a caveat against the use of pulse oximetry to prevent hyperoxemia in the neonatal population, whereas others suggest it is an important advancement. The affect of the use of pulse oximetry on respiratory morbidity and mortality has not been established, and suggestions that all mechanically ventilated patients should be continuously monitored are unsubstantiated.

Child↗

An adolescent case of sulfhemoglobinemia associated with high-dose metoclopramide and N-acetylcysteine.

We describe the case of an adolescent girl who received high-dose metoclopramide in combination with oral N-acetylcysteine therapy for acute acetaminophen toxicity. Whole blood-sample analysis for abnormal hemoglobin pigments established the diagnosis of sulfhemoglobinemia. Metoclopramide has been shown to cause sulfhemoglobinemia, particularly when used in repeated high doses. Although N-acetylcysteine alone has not been associated as the cause, we suggest that sulfhemoglobine-mia is a potential complication in patients treated with metoclopramide for the nausea that often accompanies oral N-acetylcysteine therapy for acetaminophen toxicity. Cyanosis without respiratory distress should suggest this diagnosis.

Acetaminophen↗

[Sickle cell anemia and pregnancy: considerations on systematic prophylactic transfusion].

Sickle cell anemia, a congenital hemolytic type of anemia due to a genetic defect in the beta chain of the globin molecule can cause severe disease. During pregnancy, the risk for preeclampsia and deep venous thrombosis is increased in patients with sickle cell anemia. Occlusion of placenta blood vessels with rigid deformed erythrocytes can cause repeated miscarriages and intra-uterine fetal death. Repeated blood transfusions can prevent these complications by reducing the concentration of abnormal hemoglobin S. We report on the evolution of five pregnancies in three patients with sickle cell anemia who received multiple blood transfusions during gestation, and discuss advantages and risks involved in the care of such cases.

Abortion, Spontaneous↗

[On the differential diagnosis of hemolytic anemia (author's transl)].

Differential diagnosis of hemolytic anemia is discussed, with regard to the classification into corpuscular and extracorpuscular types of hemolysis. Presence of antibodies in a patient's serum, indicate extracorpuscular-acquired hemolytic anemia. Coombs test may be positive or negative according to the antibody present. A primary disease has to be excluded in each case. Abnormal hemoglobin, defect of the corpuscular-hereditary type. Direct laboratory enzyme estimation indicate enzyme deficiency (Glucose-6-P-dehydrogenase, Pyruvate-kinase, Glutathione-reductase). Hemoglobinelectrophoresis and special tests for unstable hemoglobins indicate this type of disturbance. For defect of the membrane measuring of osmotic fragility might be helpful. Activity of membrane enzymes and introduction of 32P in the fractionated membrane lipids, point out special types of a deficient membrane. 6 of our own cases are discussed.

Anemia, Hemolytic↗

Noncontraceptive applications of the levonorgestrel intrauterine system.

The introduction of an intrauterine system that releases 20 mg of levonorgestrel (LNG-IUS) directly to the uterine lining has ushered in a new era for the intrauterine device. The LNG-IUS reduces menstrual bleeding and dysmenorrhea, and is an effective nonsurgical treatment for idiopathic menorrhagia in premenopausal women. Women using the device experience significant reductions in menstrual flow and increases in hemoglobin. Abnormal uterine bleeding has become a primary indication for the use of this intrauterine device in Europe, and it is an emerging off-label indication in the United States. Women randomized to the use of the device experience a reduction in bleeding similar to that obtained by hysteroscopic procedures, and satisfaction with the results is high. The device also provides endometrial protection in combination with estrogen as postmenopausal hormone replacement therapy. In this paper, the growing literature on the emerging noncontraceptive indications for the LNG-IUS is reviewed.

Drug Delivery Systems↗