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Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nearly 25% of patients with sickle cell disease (SCD) experience central nervous system morbidity involving both large and small vessel disease. Optimal imaging methods for determining the extent of ischemia are not known. Positron emission tomography (PET) has the unique ability to show tissue function as well as structure. Reports concerning patients with non-SCD neurodegenerative disorders suggest PET may be useful in determining prognosis. We compared magnetic resonance imaging, magnetic resonance angiography, and neuropsychological testing with PET prospectively. Six patients with SCD and a history of stroke, aged 10 to 28, were enrolled. PET studies were performed on an ECAT HR 47 scanner (Siemens/CTI, Knoxville, TN) using 18-F-fluorodeoxyglucose as a tracer. PET interpretations were conducted in blinded fashion. MRI studies found two patients with only small vessel disease and four with both large and small vessel disease. In two of four subjects with large vessel disease, PET showed a corresponding metabolic abnormality and also identified an area of hypometabolism extending beyond the anatomical lesion as shown by MRI. PET did not demonstrate an abnormality corresponding with small vessel disease. Detailed neuropsychological testing demonstrated cognitive dysfunction in all cases. For some patients, PET may add sensitivity in detecting impaired metabolism in the area surrounding a major vessel infarct. However, the technique does not appear to be generally useful in characterizing small watershed or deep white matter infarcts. Larger studies, to include control subjects and carefully selected untransfused SCD patients, are needed. A combination of conventional imaging and neuropsychological testing remains the preferred evaluation for most SCD patients with neurologic symptoms.
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PMID:Role of positron emission tomography in determining the extent of CNS ischemia in patients with sickle cell disease. 1020 99

Sudden cardiac death due to ventricular arrhythmias remains a significant problem. In most studies about 50% of all death related to coronary artery disease and heart failure are sudden and unexpected and are caused by acute fatal ventricular tachycardia and fibrillation. Most of the patients suffering sudden cardiac death have some kind of structural heart disease but 80% of SCD events are associated with coronary artery disease, 10-15% with dilated and hypertrophic cardiomyopathy, and only small fraction with the less common disorders as valvular heart disease, ventricular dysplasia and cardiac involvement in sarcoidosis or amyloidosis. In some patients the anomaly responsible for sudden cardiac death is not structural but mainly electrical as in patients with the long QT syndrome, WPW syndrome or in patients with a proarrhythmic effect from antiarrhythmic drugs. In this review, data from clinical trials and other studies on on antiarrhythmic therapies have been evaluated in order to determine effective strategies for the prevention sudden cardiac death in high risk patients. Taken together with the mortality data routine prophylactic use of class I antiarrhythmic drugs in the patients survivors of acute myocardial infarction and patients with heart failure is associated with increased risk of death. Conversely beta-blockers are associated with significant reduction in nonfatal cardiac arrest in the short term trials and sudden cardiac death in long term trials. These benefits are likely due to relief ischemia, reduction of heart rate and maintenance favourable autonomic nervous system balance. Overall trial data on amiodarone suggests that this agent is effective in reducing the risk of death in survivors of cardiac arrest, post infarction patients, and patients with heart failure but the routine prophylactic use of amiodarone remains of uncertain efficacy. The physician who considers the use of antiarrhythmic medications in patients with ventricular arrhythmias must be aware of which arrhythmias are malignant or potentially malignant and which are benign and the decision to initiate antiarrhythmic therapy should be based on consideration of the patients absolute mortality risk.
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PMID:[Antiarrhythmic agents in the prevention of sudden cardiac death]. 1036 92

Renal abnormalities in sickle cell disease. Sickle cell nephropathy is indicated by sickled erythrocytes, with the consequent effects of decreased medullary blood flow, ischemia, microinfarct and papillary necrosis. Impaired urinary concentrating ability, renal acidification, hematuria, and potassium secretion are also found. There may be a causal relationship between an increase in nitric oxide synthesis and experimental sickle cell nephropathy, and some studies have indicated that the progression of sickle cell nephropathy is hemodynamically mediated. Although there are many studies showing that proteinuria, nephrotic syndrome, chronic progressive renal failure, and acute renal failure syndromes are the outcome of this disease, the pathogenic mechanism(s) and potential therapies remain to be elucidated. Survival of patients with sickle cell nephropathy who progress to end-stage renal disease (ESRD) is equal to non-diabetic ESRD patients, and graft survival rates are also similar for those who undergo renal transplantation. This article presents a historical review of the glomerular and tubular disorders associated with sickle cell nephropathy, and reviews therapeutic indications to slow its progression. Further research is needed.
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PMID:Renal abnormalities in sickle cell disease. 1088 98

Despite the unicity of its genetic mutation, Sickle cell homozygosity presents different clinical features. Our objectives were to evaluate disease severity in Senegalese patients. Sixty (60) homozygous sickle cell patients were followed up monthly during one year and disease severity was assessed using the "severity index" (SI) which is resulting from epidemiologic, clinic and biological data. Mean age was 20.13, sex ratio was 0.87 and mean age of diagnosis was 9.8 years. 90% of patients presented vaso-occlusive crisis (2.53 per patient), 73.3% had infectious episodes (1.9 per patient), 69.3% had never been transfused and 25% of patients had presented chronic complications linked to anemia or ischemia. Mean hemoglobin value was 8.1 g/dl and mean Hb F was 8.2%. Low seric ferritin was found in 1.7% of patients. Benign form of homozygous sickle cell anemia (SI< or =6) was found in 48.3% of patients. Our data confirm the relative good tolerance of homozygous sickle cell disease in Senegal. The haplotype Senegal may play an important role but others host and environmental factors operate certainly because some severe cases were identified in our patients. The identification of all these factors might contribute to a better follow up of sickle cell disease.
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PMID:New results in clinical severity of homozygous sickle cell anemia, in Dakar, Senegal. 1065 Nov 22

Sickle cell anemia and the related hemoglobinopathies are associated with a large spectrum of renal abnormalities. The patients have impaired urinary concentrating ability, defects in urinary acidification and potassium excretion, and supranormal proximal tubular function. The latter is manifest by increased secretion of creatinine and by reabsorption of phosphorus and beta(2)-microglobulin. Young patients with sickle cell disease (SCD) have supranormal renal hemodynamics with elevations in both effective renal plasma flow (ERPF) and glomerular filtration rate (GFR). These parameters decrease with age as well as following the administration of prostaglandin inhibitors. Proteinuria, a common finding in adults with sickle cell disease, may progress to the nephrotic syndrome. Proteinuria, hypertension, and increasing anemia predict end-stage renal disease (ESRD). While ESRD can be managed by dialysis and/or renal transplantation, there may be an increased rate of complications in renal transplant recipients with SCD. Hematuria is seen in individuals with all of the SCDs as well as with sickle cell trait. In most cases the etiology of the hematuria turns out to be benign. However, there does appear to be an increased association between SCD and renal medullary carcinoma. Therefore, those SCD patients who present with hematuria should initially undergo a thorough evaluation in order to exclude this aggressive neoplasm. Papillary necrosis may occur due to medullary ischemia and infarction. Erythropoietin levels are usually lower than expected for their degree of anemia and decrease further as renal function deteriorates. An abnormal balance of renal prostaglandins may be responsible for some of the changes in sickle cell nephropathy. Acute renal failure is a component of the acute multiorgan failure syndrome (MOFS). Finally, progression of sickle cell nephropathy to ESRD may be slowed by adequate control of hypertension and proteinuria. However, the prevention of the renal complications of SCD will require a cure for this genetic disorder.
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PMID:Renal abnormalities in sickle cell disease. 1142 1

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.
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PMID:Hypoxia/reoxygenation causes inflammatory response in transgenic sickle mice but not in normal mice. 1093 Apr 36

Priapism is a prolonged, painful, penile erection that fails to subside despite orgasm. An erection lasting longer than 4-6 h is considered to be priapic; nevertheless, pain does not usually ensue until 6-8 h have elapsed. Priapism is considered a failure of the detumescence mechanism, which may be due to excess release of contractile neurotransmitters, obstruction of draining venules, malfunction of the intrinsic detumescence mechanism, or prolonged relaxation of intracavernosal smooth muscle. There are essentially two main types of priapism: high flow (non-ischemic) and low flow (ischemic). Low flow priapism is the more common form, and it is associated with a decrease in venous outflow and vascular stasis that, in turn, cause tissue hypoxia and acidosis. This form of priapism is usually quite painful because of tissue ischemia. Penile blood aspirated from cavernous spaces appears dark in color. Immediate treatment is necessary or penile fibrosis will ensue. High flow priapism is usually due to trauma, although, on rare occasions it has been idiopathic or due to sickle cell disease. The hallmark of this type of priapism is an increase in arterial inflow in the setting of normal venous outflow. Aspirated penile blood is noted to be bright red and has a high pO(2). This form of priapism is not usually painful because it is non-ischemic. Treatment is dependent on the wishes of the patient but is not mandatory. International Journal of Impotence Research (2000) 12, Suppl 4, S133-S139.
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PMID:Priapism. 1103 1

Vasospasm can have many different causes and can occur in a variety of diseases, including infectious, autoimmune, and ophthalmic diseases, as well as in otherwise healthy subjects. We distinguish between the primary vasospastic syndrome and secondary vasospasm. The term "vasospastic syndrome" summarizes the symptoms of patients having such a diathesis as responding with spasm to stimuli like cold or emotional stress. Secondary vasospasm can occur in a number of autoimmune diseases, such as multiple sclerosis, lupus erythematosus, antiphospholipid syndrome, rheumatoid polyarthritis, giant cell arteritis, Behcet's disease, Buerger's disease and preeclampsia, and also in infectious diseases such as AIDS. Other potential causes for vasospasm are hemorrhages, homocysteinemia, head injury, acute intermittent porphyria, sickle cell disease, anorexia nervosa, Susac syndrome, mitochondriopathies, tumors, colitis ulcerosa, Crohn's disease, arteriosclerosis and drugs. Patients with primary vasospastic syndrome tend to suffer from cold hands, low blood pressure, and even migraine and silent myocardial ischemia. Valuable diagnostic tools for vasospastic diathesis are nailfold capillary microscopy and angiography, but probably the best indicator is an increased plasma level of endothelin-1. The eye is frequently involved in the vasospastic syndrome, and ocular manifestations of vasospasm include alteration of conjunctival vessels, corneal edema, retinal arterial and venous occlusions, choroidal ischemia, amaurosis fugax, AION, and glaucoma. Since the clinical impact of vascular dysregulation has only really been appreciated in the last few years, there has been little research in the according therapeutic field. The role of calcium channel blockers, magnesium, endothelin and glutamate antagonists, and gene therapy are discussed.
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PMID:Vasospasm, its role in the pathogenesis of diseases with particular reference to the eye. 1128 96

Sickle cell anemia (SCA) is a disease caused by production of abnormal hemoglobin, which binds with other abnormal hemoglobin molecules within the red blood cell to cause rigid deformation of the cell. This deformation impairs the ability of the cell to pass through small vascular channels; sludging and congestion of vascular beds may result, followed by tissue ischemia and infarction. Infarction is common throughout the body in the patient with SCA, and it is responsible for the earliest clinical manifestation, the acute pain crisis, which is thought to result from marrow infarction. Over time, such insults result in medullary bone infarcts and epiphyseal osteonecrosis. In the brain, white matter and gray matter infarcts are seen, causing cognitive impairment and functional neurologic deficits. The lungs are also commonly affected, with infarcts, emboli (from marrow infarcts and fat necrosis), and a markedly increased propensity for pneumonia. The liver, spleen, and kidney may experience infarction as well. An unusual but life-threatening complication of SCA is sequestration syndrome, wherein a considerable amount of the intravascular volume is sequestered in an organ (usually the spleen), causing vascular collapse; its pathogenesis is unknown. Finally, because the red blood cells are abnormal, they are removed from the circulation, resulting in a hemolytic anemia. For the patient with SCA, however, the ischemic complications of the disease far outweigh the anemia in clinical importance.
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PMID:Sickle cell anemia. 1145 73

We describe 2 pediatric patients with sickle cell disease (SCD) who developed seropositive juvenile rheumatoid arthritis (JRA). Both patients have severe joint damage, the compound effect of both disease processes. The bone and cartilage destruction, which poses serious therapeutic challenges, highlights the difficulty of making a diagnosis of chronic inflammatory disease in the setting of SCD. There may be a correlation between increased levels of tumor necrosis factor-alpha in the synovial tissue of joints damaged by arthritis and local sickling. The resultant ischemia and corresponding inflammatory infiltrates could in turn worsen existing synovial proliferation and cartilage destruction as well as trigger further sickling.
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PMID:Co-existent sickle cell disease and juvenile rheumatoid arthritis. Two cases with delayed diagnosis and severe destructive arthropathy. 1218 Jul 51


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