PubMed · 16913372
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Sandra Anglin. Screen test for all.. https://doi.org/10.7748/ns.20.47.28.s25
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A 6-year-old female with homozygous sickle cell disease had a central venous access device (CVAD) placed to facilitate chronic erythrocytapheresis. Erythrocytapheresis was ineffective due to the rare pinch-off syndrome causing communication between the dual lumen tubing. Awareness of and monitoring for the pinch-off syndrome is indicated in people with sickle cell disease and a CVAD for chronic erythrocytapheresis.
There are many practical situations where observation of the primary variable Y for individuals in a population is incomplete and depends on some auxiliary variables X that are potentially correlated with Y. We consider parameter estimation for the distribution of Y with the incomplete data, without specifying the underlying association between Y and X. The approach is based on a class of pseudoscore functions using available information of X. We demonstrate the consistency and asymptotic normality of the estimators and study their finite-sample properties in various situations via simulation. The methodology is illustrated by an example involving kindergarten readiness skills in children with sickle cell disease.
Pulmonary hypertension is a highly prevalent complication of sickle cell disease and is a strong risk factor for early mortality. However, the pathophysiologic mechanisms leading to pulmonary vasculopathy remain unclear. Transgenic mice provide opportunities for mechanistic studies of vascular pathophysiology in an animal model. By microcardiac catheterization, all mice expressing exclusively human sickle hemoglobin had pulmonary hypertension, profound pulmonary and systemic endothelial dysfunction, and vascular instability characterized by diminished responses to authentic nitric oxide (NO), NO donors, and endothelium-dependent vasodilators and enhanced responses to vasoconstrictors. However, endothelium-independent vasodilation in sickle mice was normal. Mechanisms of vasculopathy in sickle mice involve global dysregulation of the NO axis: impaired constitutive nitric oxide synthase activity (NOS) with loss of endothelial NOS (eNOS) dimerization, increased NO scavenging by plasma hemoglobin and superoxide, increased arginase activity, and depleted intravascular nitrite reserves. Light microscopy and computed tomography revealed no plexogenic arterial remodeling or thrombi/ emboli. Transplanting sickle marrow into wild-type mice conferred the same phenotype, and similar pathobiology was observed in a nonsickle mouse model of acute alloimmune hemolysis. Although the time course is shorter than typical pulmonary hypertension in human sickle cell disease, these results demonstrate that hemolytic anemia is sufficient to produce endothelial dysfunction and global dysregulation of NO.