Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydroxyurea can increase fetal hemoglobin (HbF) and improve the clinical course of sickle cell disease (SCD) patients. However, several issues of hydroxyurea therapy remain unresolved, including differences in patients' drug clearance, predictability of drug response, reversibility of sickle cell disease-related organ damage by hydroxyurea, and the efficacy of elevated HbF. We treated two patients with hydroxyurea for periods of 1 to 4 years, monitoring clinical course and laboratory parameters at regular intervals. The first patient (patient A) had a history of chronic pain and extensive hospitalizations. The second patient (patient B) had a history of stroke and refused to continue with chronic transfusion therapy and chelation. Both patients showed a fivefold to tenfold increase in HbF (5% to 25%, 3% to 31%). However, patient A developed an acute chest syndrome, despite an HbF level of 20%. After red blood cell transfusions for hypoxia, the HbF level decreased to 5%. When hydroxyurea dosage was increased, pancytopenia developed and was not resolved until 2 months after hydroxyurea was discontinued; Patient B developed a cerebral hemorrhage on hydroxyurea; he died shortly thereafter. His HbF level was 21% before death. We noted an increase in HbF and a general improvement in the two patients. However, both experienced major SCD-related complications despite HbF levels over 20%. Our findings also suggest that the progressive vascular changes associated with SCD are unlikely to be dramatically affected by increased HbF levels. Because neither the efficacy nor the toxicity of hydroxyurea have been thoroughly investigated, physicians should be cautious in prescribing hydroxyurea for patients with SCD before completion of the National Clinical Trial.
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PMID:A cautionary note regarding hydroxyurea in sickle cell disease. 750 9

We report serial CNS findings in a girl with sickle cell disease and stroke. Religious considerations precluded transfusion and bone marrow transplantation; therefore, she received single-agent hydroxyurea therapy for almost 6 years. MR angiography showed that vascular patency improved, although diffuse cerebral atrophy slowly worsened. Hydroxyurea can be effective in treating vasculopathy, but it might not prevent the progression of parenchymal damage in advanced disease.
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PMID:The effect of hydroxyurea on vasculopathy in a child with sickle cell disease. 1242 25

Stroke is an important and common complication of sickle cell disease (SCD), affecting children as well as adults. Clinically evident stroke, usually brain infarction, is usually associated with stenosis or occlusion of the intracranial arteries of the Circle of Willis, sometimes with formation of moyamoya (a Japanese word for "hazy" or "like a puff of smoke" that describes the appearance of a abnormal microvasculature on angiography believed secondary to internal carotid artery stenosis or occlusion and the resultant extensive collateralization). Several types of intracranial hemorrhage are observed but usually in older children and adults. Cerebrovascular diseases restricted to small vessels may go unrecognized but is associated with cognitive and learning problems. Prevention of recurrent stroke has been accomplished with chronic blood transfusion. A primary prevention strategy for clinical stroke, based on the Stroke Prevention in Sickle Cell Anemia Trial, has been tested in a randomized clinical trial. Over 2,000 young children with SCD were screened with transcranial Doppler ultrasound (TCD) to detect elevated blood flow velocity indicative of vessel disease and high risk of future stroke. Those randomized to standard care (no transfusion) had a 10%/year risk of stroke, which was reduced >90% with chronic transfusion. This approach is the only primary stroke prevention strategy so far tested in SCD in a randomized controlled trial. Silent lesions on magnetic resonance imaging are associated with an approximately 1.5%/year risk of clinical stroke and a trial is now starting in children with these lesions who do not meet Stroke Prevention in Sickle Cell Anemia Trial criteria for transfusion based on TCD. A controlled trial, based on intervention for nocturnal hypoxemia, is also underway. Hydroxyurea, bone marrow transplantation, antiplatelet, and antithrombotic agents may work but have not been tested in primary prevention in a systematic way. If early and repeated, TCD screening of children, as recommended by National Heart Lung and Blood Institute and the American Stroke Association, were implemented broadly the incidence of new strokes could be greatly reduced in these children.
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PMID:Sickle cell disease: primary stroke prevention. 1516 93

Children with sickle disease are at high risk for ischemic stroke and transient ischemic attacks, usually secondary to intracranial arteriopathy involving the terminal internal carotid and proximal middle cerebral and anterior cerebral arteries, which may be diagnosed using transcranial Doppler ultrasound or magnetic resonance angiography (MRA). Other central nervous system (CNS) complications include seizures and coma, which may be secondary to ischemic stroke, sinovenous thrombosis, reversible posterior leukoencephalopathy, or acute demyelination. The immediate priority after an acute CNS event is to improve cerebral oxygenation with oxygen supplementation to maintain peripheral saturation measured using pulse oximetry between 96% and 99%, and a simple transfusion of packed cells within an hour of presentation if the patient's hemoglobin is less than 10 g/dL. The patient then should have erythrocytapheresis or manual exchange to reduce the hemoglobin S percentage to below 30%. Computed tomography to exclude hemorrhage is mandatory and MR T2-weighted imaging with MRA, fat-saturated imaging of the neck (dissection), MR venography (sinovenous thrombosis), and diffusion-weighted imaging usually distinguishes between arterial ischemic stroke and the differential diagnoses. Comatose patients with widespread focal or global cerebral edema may have good functional outcome after surgical decompression. Anticoagulation may be indicated for dissection or sinovenous thrombosis and steroids for demyelination. Blood pressure should be reduced slowly if raised in patients with reversible posterior leukoencephalopathy. Seizures should be treated aggressively and electroencephalogram monitoring should be done to exclude subclinical seizures if the patient is unconscious. Hemorrhagic stroke may require craniectomy and drainage and/or management of vasospasm. Interventional neuroradiology with coils is an alternative to surgical clipping for aneurysms. For secondary prevention, regular blood transfusion to hemoglobin S of less than 30% reduces the risk of recurrent stroke from approximately 67% to approximately 10%. Hydroxyurea and phlebotomy may be used in patients who are alloimmunized. Moyamoya syndrome is a risk factor for recurrence despite prophylactic blood transfusion. Revascularization may prevent additional stroke. Bone marrow transplantation may be offered to patients with human leukocyte antigen-compatible siblings. Blood transfusion prevents stroke in patients with velocities greater than 200 cm per second on TCD; a phase III trial studying the prevention of the progression of silent infarction is being done. Emerging primary prophylaxis regimens being tested include citrulline and arginine, aspirin, and overnight oxygen supplementation. Physicians caring for children with sickle cell disease also should ensure adequate nutrition, including five servings of fruit and vegetables a day. The role of vitamin supplementation is controversial, particularly when patients must take daily penicillin prophylaxis.
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PMID:Stroke in Children with Sickle Cell Disease. 1527 58

Much progress has been made during the past several decades in gaining understanding about the natural history of sickle cell disease and management approaches aimed at treating or even preventing certain disease complications. The characterization of the human genome now offers the opportunity to understand relationships regarding how gene polymorphisms as well as how environmental factors affect the sickle cell disease phenotype, i.e., the individual patient's overall clinical severity as well as their specific organ function. This chapter explores some of these recent advances in knowledge. In Section I, Dr. Michael DeBaun characterizes the problem of silent stroke in sickle cell disease, comparing and contrasting its clinical and neuroimaging features with overt stroke. Combined, these events affect virtually 40% of children with sickle cell anemia. New understanding of risk factors, associated clinical findings, and imaging technologies are impacting substantially on treatment options. The appreciable cognitive dysfunction and other sequelae of silent infarct demand more effective treatments and ultimate prevention. In Section II, Dr. Charles Quinn addresses the conundrum of why some patients with sickle cell disease do well whereas others fare poorly. Some risk factors have been known for years, based upon careful study of hundreds of patients by the Cooperative Study for Sickle Cell Disease and investigators studying the Jamaican newborn cohort. Other prognostic measures have only recently been defined. Dr. Quinn devotes special attention to stroke and chest syndrome as organ-related complications but also describes attempts to measure overall disease severity and to predict survival. Recently, investigators have attempted to predict factors responsible for early mortality in children and following onset of pulmonary hypertension in adults. In Section III, Dr. Martin Steinberg reviews pharmacologic approaches to sickle cell disease and the rationale for their use. In addition to the inhibition of hemoglobin S polymerization, newer targets have been defined during the past one to two decades. These include the erythrocyte membrane, changes in the red cell intracellular content (especially loss of water), endothelial injury, and free radical production. Hydroxyurea treatment attracted the greatest interest, but many uncertainties remain about its long-term benefits and toxicities. Newer "anti-sickling" agents such as decitabine and short-chain fatty acids also receive attention. Prevention of red cell dehydration, "anti-endothelial" therapy, and marshalling the potentially beneficial effects of nitric oxide are other new and exciting approaches.
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PMID:Sickle cell disease. 1556 75

Hydroxyurea (HU) is considered to be the most successful drug therapy for severe sickle cell disease (SCD). Nevertheless, questions remain regarding its benefits in very young children and its role in the prevention of cerebrovascular events. There were 127 SCD patients treated with no attempt to reach maximal tolerated doses who entered the Belgian Registry: 109 for standard criteria and 18 who were at risk of stroke only. During 426 patient-years of follow-up for patients with standard criteria, 3.3 acute chest syndromes, 1.3 cerebrovascular events, and 1.1 osteonecrosis per 100 patient-years were observed. A subgroup of 32 patients followed for 6 years experienced significant benefit over this period. In each subgroup of children (younger than 2 years, 2-5, 6-9, and 10-19 years) followed for 2 years, clinical and biologic changes were similar, except for children younger than 2 years who had no total hemoglobin increase and remained at risk of severe anemia. In 72 patients evaluated by transcranial Doppler studies (TCD), 34 patients were at risk of primary stroke and only 1 had a cerebrovascular event after a follow-up of 96 patient-years. These results confirm the benefit of HU, even in very young children, and its possible role in primary stroke prevention.
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PMID:Hydroxyurea for sickle cell disease in children and for prevention of cerebrovascular events: the Belgian experience. 1560 17

Stroke is one of the major complications in children with sickle cell disease (SCD). Ischemic stroke is associated with small asymptomatic subcortical infarcts to large territorial lesions causing major disability. Intracranial hemorrhages may be caused by aneurysm rupture or by leakage from moyamoya vessels or venous sources. There have been no acute stroke treatment studies in SCD, but hydration and exchange transfusion are often recommended. However, there is an evidence base for primary and to some extent secondary stroke prevention. Primary prevention of stroke was demonstrated in the Stroke Prevention Trial in Sickle Cell Anemia (STOP), in which children with transcranial Doppler (TCD) mean blood flow velocities of 200 cm/second (previously shown to indicate high stroke risk) or higher were randomized to either regular blood transfusions or no transfusion. The study showed a very significant 90% reduction in first stroke with transfusion. In STOP2, discontinuing transfusions after 30 months or more (even with normal TCD) resulted in a high rate of reversion to abnormal TCD values and stroke. TCD screening of all children with SCD, and initiation and maintenance of chronic transfusion to maintain hemoglobin S below 30% in the high-risk group, is the only proven prevention strategy for stroke in SCD. Hydroxyurea is being studied as secondary stroke prevention at this time. No recommendation specific to SCD regarding the use of antiplatelet agents or anticoagulants in ischemic stroke can be made. Bone marrow transplantation can be curative for SCD, and limited data support its use to prevent stroke in SCD.
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PMID:Treatment and prevention of stroke in children with sickle cell disease. 1703 71

Sickle cell disease can be corrected by hematopoietic cell transplantation but success is limited by low availability of matched related/unrelated donors and comorbidities leading to the increased transplant-related morbidity/mortality. There is a need for expanded donor pools and reduced intensity regimens. We describe a case of a second unrelated cord blood transplant after a novel preparative regimen in a child with sickle cell disease related stroke and liver fibrosis. Hydroxyurea, rituximab, and alemtuzumab were followed by thiotepa and low dose total body irradiation before unrelated cord blood transplant. Rapid full donor chimerism and improved performance status was achieved and sustained over 2 years after transplant.
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PMID:Transplantation of a child with sickle cell anemia with an unrelated cord blood unit after reduced intensity conditioning. 1716 57

Hydroxyurea has hematologic and clinical efficacy in sickle cell anemia (SCA), but its effects on transcranial Doppler (TCD) flow velocities remain undefined. Fifty-nine children initiating hydroxyurea therapy for clinical severity had pretreatment baseline TCD measurements; 37 with increased flow velocities (> or = 140 cm/s) were then enrolled in an institutional review board (IRB)-approved prospective phase 2 trial with TCD velocities measured at maximum tolerated dose (MTD) and one year later. At hydroxyurea MTD (mean +/- 1 SD = 27.9 +/- 2.7 mg/kg per day), significant decreases were observed in the right middle cerebral artery (MCA) (166 +/- 27 cm/s to 135 +/- 27 cm/s, P < .001) and left (MCA) (168 +/- 26 cm/s to 142 +/- 27 cm/s, P < .001) velocities. The magnitude of TCD velocity decline was significantly correlated with the maximal baseline TCD value. At hydroxyurea MTD, 14 of 15 children with conditional baseline TCD values improved, while 5 of 6 with abnormal TCD velocities whose families refused transfusions became less than 200 cm/s. TCD changes were sustained at follow-up. These prospective data indicate that hydroxyurea can significantly decrease elevated TCD flow velocities, often into the normal range. A multicenter trial is warranted to determine the efficacy of hydroxyurea for the management of increased TCD values, and ultimately for primary stroke prevention in children with SCA.
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PMID:Hydroxyurea therapy lowers transcranial Doppler flow velocities in children with sickle cell anemia. 1818 80

In the past two decades, two landmark randomized controlled trials (RCT) have been completed among individuals with sickle cell disease (SCD), the Multi-center Study of Hydroxyurea (MSH) trial and the Stroke Prevention (STOP) trial. The MSH trial tested the hypothesis that hydroxyurea will reduce the frequency of painful episodes for adults with hemoglobin SS who had a history of 3 or more painful episodes per year. The STOP trial tested the hypothesis that among children with hemoglobin SS and an elevated transcranial Doppler (TCD) velocity measurement, blood transfusion therapy would decrease the risk of an initial stroke. After completion, both trials have defined standard care for individuals with hemoglobin SS. The purpose of this review is to examine the limitations of the MSH and STOP trials. In the context of these trials, we will examine the effects of narrow inclusion criteria that primarily include participants with hemoglobin SS and secondary analyses that are prone to false-positive results. In addition, we describe how after publication of these two trials use of hydroxyurea and TCD assessment has drifted towards a standard practice without evidence of therapeutic efficacy among groups that were excluded from the trials. Finally, we suggest that rigorously conducted RCTs or at the minimum multicenter observation studies with strong methodology should be performed in these excluded subgroups to confirm a benefit of hydroxyurea or TCD measurement.
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PMID:Limitations of clinical trials in sickle cell disease: a case study of the Multi-center Study of Hydroxyurea (MSH) trial and the Stroke Prevention (STOP) trial. 1802 68


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