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S Charache

Publications and source records attributed to S Charache.

At least 37 records · Page 2Linked to original sources
PubMed1992

Hydroxyurea induction of fetal hemoglobin synthesis in sickle-cell disease.

In the past 8 years, it has become apparent that some cytotoxic drugs that interfere with DNA replication can reprogram erythroid progenitors to switch from adult hemoglobin to fetal hemoglobin (HbF) production. Hydroxyurea has now been shown to substantially increase HbF in patients with sickle cell anemia. Since HbF interferes with sickle hemoglobin polymerization, hydroxyurea may become an important therapeutic agent for patients with sickle cell anemia.

Anemia, Sickle Cell↗
PubMed1991

Hemoglobin aggregation and pseudosickling in vitro of hemoglobin Setif-containing erythrocytes.

Erythrocytes from individuals heterozygous for hemoglobin Setif (alpha 94 Asp----Tyr) sickle in vitro without deoxygenation when incubated in chloride buffer due to hemoglobin aggregation. We now report quantitative studies of hemoglobin polymerization and deformability in these cells. Hemoglobin polymer gradually increased in intact cells during a 24 h incubation period at 24 degrees C. After 24 hr, about 80% of the cells in 290 mOsm sodium chloride buffer contained polymer which appeared as short rods compared to greater than 99% containing polymer at 450 mOsm. Similar proportions of cells were morphologically sickled. Deformability of erythrocytes with 40% hemoglobin Setif incubated in 290 mOsm buffer at 37 degrees C decreased to 80% of normal by 210 min but in 450 mOsm decreased to 50% after only 30 min as measured by the ektacytometer. However, at 4 degrees C deformability remained normal even in 450 mOsm buffer. The solubility of gelled hemolysate containing 40% hemoglobin Setif was 24 g/dl and 21 g/dl at 290 and 459 mOsm buffer respectively. The gel persisted at 4 degrees C with a solubility of 26 g/dl, but melted when dialyzed into sodium phosphate or potassium phosphate buffer. These data suggest that hemoglobin polymerization, reduced deformability, and sickling of hemoglobin Setif-containing erythrocytes are related to reduced hemoglobin solubility. The rate and extent of intracellular polymerization in vitro are considerably reduced (as in the case of sickle trait) compared with erythrocytes from individuals with sickle cell anemia. Hence, the slower kinetics of hemoglobin aggregation in hemoglobin Setif-containing cells provide an alternate system for studying hemoglobin polymerization and abnormal rheology.

Anemia, Sickle Cell↗
PubMed1991

Hydroxyurea as treatment for sickle cell anemia.

Hydroxyurea may be the most promising drug suggested thus far as a treatment for patients with sickle cell anemia, but its safety and efficacy remain unproved, and it probably will not be evaluable for several years. It is not "the answer" for the disease, it seems likely that crises will not be eliminated by treatment, and at this time its use should be reserved for seriously affected adult patients who can participate in a controlled clinical trial. Every hematologist, internist, or pediatrician sees a few patients who are so severely afflicted by sickle cell anemia that their lives seem totally blighted. It is very tempting to consider treating them with hydroxyurea, because the drug is available in any pharmacy, but it is equally important to consider whether the treatment would accomplish any more than treating the physician's own sense of futility, or making the patient feel that "something was being done." If hydroxyurea were as safe as folic acid, treatment for these purposes would be reasonable. It is not, but its use may still be appropriate (although illegal unless used under an Investigational New Drug Agreement, because its use for this purpose is not approved by the FDA). Whether or not it is legal, prescription of hydroxyurea for patients with sickle cell anemia would be ethical or proper only if the potential risks, the variability of the Hb F response, and the lack of proof of clinical efficacy were clearly explained to potential recipients.

Anemia, Sickle Cell↗
PubMed1990

Treatment of sickle cell anemia with hydroxyurea and erythropoietin.

BACKGROUND: Hydroxyurea increases the production of fetal hemoglobin (hemoglobin F) in patients with sickle cell anemia and therefore has the potential for alleviating both the hemolytic and vaso-occlusive manifestations of the disease. There is preliminary evidence that recombinant human erythropoietin may also increase hemoglobin F production. METHODS AND RESULTS: We treated five patients with sickle cell disease with escalating doses of intravenous erythropoietin for eight weeks. Three of these patients were subsequently treated with daily doses of oral hydroxyurea. After the optimal dose was determined, erythropoietin was then given along with hydroxyurea for four weeks. Treatment with erythropoietin, either alone or in combination with hydroxyurea, had no significant effect on the percentage of hemoglobin F-containing reticulocytes (F reticulocytes) or red cells (F cells). In contrast, hydroxyurea treatment was associated with a 3-to-25-fold increase in F reticulocytes, a 1.6-to-7-fold increase in F cells, and a 2.3-to-16-fold increase in the percentage of hemoglobin F. In all three patients given hydroxyurea, treatment with this drug was associated with reduced hemolysis, shown by decreases in serum bilirubin and lactic dehydrogenase and prolongation of red-cell survival. Hydroxyurea treatment also resulted in a decrease in the percentage of irreversibly sickled cells and sickling at partial oxygen saturation, an increase in oxygen affinity and total red-cell cation content, and a reduction in potassium-chloride cotransport. All three patients had a decrease in the number of pain crises. CONCLUSIONS: This study confirms that hydroxyurea therapy increases hemoglobin F production and provides objective evidence that hydroxyurea reduces the rate of hemolysis and intracellular polymerization of hemoglobin S. In contrast, recombinant human erythropoietin, whether alone or in combination with hydroxyurea, offers no measurable benefit.

Administration, Oral↗
PubMed1990

Fetal hemoglobin, sickling, and sickle cell disease.

Increased numbers of F cells and large amounts of Hb F/F cell appear to produce clinical benefit in rare variants of sickle cell disease and probably in more commonly encountered patients. Fetal hemoglobin interferes with polymerization of Hb S in vitro, but laboratory studies carried out with homogeneous hemoglobin solutions are inadequate models of events in vivo, because RBCs are heterogeneous in their MCHC and Hb F content. Studies of hemoglobin switching in sheep, in tissue culture, and then in baboons led to use of 5-azacytidine for induction of increased Hb F synthesis in SS patients. Drug trials were successful but the theory that led to them was not. An alternate theory, not without flaws, led to the use of hydroxyurea. Chronic administration of the drug can lead to very impressive increases in Hb F synthesis and apparent clinical benefit. It is not clear that such clinical benefit is real rather than a placebo effect. Nor is it entirely clear that all of the effect of hydroxyurea can be related to increased production of F cells and increased F/F cell. Controlled clinical trials and studies of the properties of RBCs from treated patients may answer those questions. It is also likely that they will not only raise still other questions but probably show that our current understanding of the biology and treatment of sickle cell disease is far from complete.

Adolescent↗
PubMed1990

Delayed intracranial hemorrhage following cerebral infarction in sickle cell anemia.

Clinical and necropsy findings in 11 patients with sickle cell anemia (SS) indicate that intracranial hemorrhage (IH) is a delayed sequela of the same vasculopathy that causes cerebral infarction during childhood. Evidence of prior cerebral infarction during childhood included hemiparesis, seizures, an episode of coma, or mental retardation. Computerized tomography (CT) scans showed cerebral infarcts with lucent areas and dilated ventricles or cerebral atrophy. CT or magnetic resonance imaging (MRI) scans after the intracranial hemorrhage demonstrated intraventricular or intracerebral hemorrhages. Angiography or autopsy in seven patients showed widespread vascular occlusion and narrowing of arterial vessels. Moyamoya with internal carotid artery occlusion was identified in two cases. At the time of the IH, three patients were being treated with prophylactic transfusion regimens. We hypothesize that the central nervous system vasculopathy progresses over time and that arterial narrowing in both large and small vessels secondary to endothelial hyperplasia is followed by neovascularization and hemorrhage. Recognition of this pattern of delayed intracranial hemorrhage following cerebral infarction should encourage more intensive evaluation aimed at developing rational interventional therapy prior to a terminal intracranial hemorrhage.

Adolescent↗
PubMed1989

Effect of hydroxyurea on the rheological properties of sickle erythrocytes in vivo.

We have monitored the rheological effects of hydroxyurea (HU) on erythrocytes obtained from two patients with severe sickle cell anemia who were enrolled in a therapeutic trial of this drug. Erythrocyte membrane stability and whole cell and membrane deformability of red cells from treated and untreated patients and normal controls were determined in room air using an ektacytometer--a laser viscodiffractometer. The percentage of dense cells was quantitated by centrifugation on a discontinuous Stractan density gradient. F reticulocytes (FR), absolute F reticulocytes (AFR), and F cells (FC) were determined by single-cell radial immunolgic assays. After 1 year of treatment with HU, there was a significant increase in the level of hemoglobin (Hb) F, FR, AFR, and FC. The degree of anemia remained the same, but there was significant increase in the mean cell volume (MCV) and a significant decrease in the mean corpuscular Hb concentration (MCHC). Whole cell deformability improved by twofold, but membrane stability remained within normal limits. The hydration status of sickle erythrocytes improved as was indicated by a change toward normal in gradient osmotic ektacytometry, an increase in RBC K+ content, a decrease in percent of dense cells, and a decrease in the MCHC. The data indicate that, in addition to its effect on the production of Hb, F, HU has a salutary effect on whole cell deformability and on the hydration status of sickle erythrocytes. Determination of the rheological properties of erythrocytes may be of value in monitoring the response to HU.

Anemia, Sickle Cell↗
PubMed1989

Laboratory evaluation of differential white blood cell count information from the Coulter S-plus IV and Technicon H-1 in patient populations requiring rapid "turnaround" time.

Automated differential counts produced by the Coulter S-Plus IV (S + 4) and the Technicon H-1 (H-1) were compared with routine and reference manual differentials with the use of samples from the adult emergency room (ER) and the neonatal intensive care unit (NICU), populations in which rapid reporting of laboratory results is considered important. Error rates for routine technologists were 9.3% in the ER and 15.3% in the NICU. Error rates for the two instruments were higher than those for technologists with samples from the ER but could be reduced to 4-5% if instrument flags and additional criteria were used to signal the need for a conventional differential. Instrument error rates were higher yet with NICU samples, and specificity was very low (10% for each device). There were small differences between the instruments in detection of immature neutrophils, but flags from the H-1 were more specific (except for detection of nucleated red blood cells in samples from the ER). If either instrument were used in an adult ER and flags and additional criteria were used to signal the need for conventional differentials, 64-75% fewer manual counts would be performed with no decrease in accuracy and a considerable improvement in turnaround time.

Blood Specimen Collection↗
PubMed1987

Hematologic changes during sexual maturation. Why do black adolescents have low hemoglobin concentrations?

A group of black adolescents stratified by age and sexual maturity (Tanner stage) had electronic blood counts determined. Hemoglobin, hematocrit, and red cell count were lower than the means reported for white or Hispanic children of the same age. The difference could not be explained by iron deficiency, but the data were insufficient to exclude alpha thalassemia as a cause.

Adolescent↗
PubMed1987

Noninvasive assessment of tissue iron stores.

Multivariate regression methods were used to create two equations for calculation of the "iron index," a predictor of bone marrow iron scores. With the use of the most efficient cut-off point, approximately 90% of 210 patients could be diagnosed correctly. Selection of a criterion that minimizes false negatives (missed iron deficiency) would increase the number of unnecessary bone marrow aspirations, but, even then, more than a third of such tests could be avoided. Rapid turnaround time would be desirable for all measurements used to calculate the iron index, although it is recognized that for most hospitalized patients the length of hospital stay is determined by severity of an underlying disease, not the presence of anemia.

Anemia↗
PubMed1987

Abdominal pain in sickle cell disease: the role of CT.

Patients with either homozygous or heterozygous sickle cell disease may have frequent episodes of abdominal pain and/or fever of uncertain cause. While many of these episodes represent a so-called sterile crisis, the possibility of gross organ infarction and rupture, infection, or other complication cannot be ignored. Computed tomography (CT) was used to evaluate 30 such patients. Virtually all patients had splenic abnormalities, which could be considered clinically significant (rupture, hemorrhage) or insignificant (calcified spleen). In four patients hepatic abnormalities were found, including one case of multiple liver infarction, one of hepatic abscess, and two of retained intrahepatic gallstones after cholecystectomy. Two patients had significant acute renal abnormalities, including one case of interstitial nephritis and one of renal vein thrombosis. One patient had a ruptured periappendiceal abscess and one a pericolonic abscess. One patient had an abscess around a total hip replacement. CT was found to be an excellent and relatively noninvasive means of both initial investigation and subsequent follow-up.

Abscess↗