MRI and NIRS in SS Patients and Mice

镰状细胞病的一个主要特征是导致低血流、低血流灌注、血液和组织缺氧的事件，这些事件既是血管闭塞的预置因素，也是血管闭塞的后果。我们建议检验假设的限度，即HBF、饮食中的精氨酸和羟基尿素的水平都影响血流灌注和血氧，尽管机制不同。我们将结合使用磁共振成像(MRI)和近红外光谱(NIRS)来测量人类镰状细胞患者和我们开发和表征的新的镰状转基因小鼠的血氧含量、灌注量和血容量。在授权期开始时，我们的新磁共振研究中心将使用最先进的4特斯拉人类和9.4特斯拉动物系统运行超过18个月。我们已经使用我们之前描述的镰刀结构，小鼠α-和α-HbF，产生了专门表达具有三个水平的HBF的人镰状血红蛋白的小鼠 β-珠蛋白基因敲除，以及三种不同的人类伽马转基因。我们发现，HbF从3%到20%到40%的进行性增加与红细胞压积(22%到34%到40%)的进行性增加、网织红细胞数量的进行性减少(从60%到30%到13%)以及寿命的延长(从45天到194天到368天)相关。使用BOLD-MRI或血氧依赖磁共振成像和T2图，我们已经证明，与对照小鼠相比，高水平表达人和β-S-珠蛋白的转基因小鼠的大脑、肝脏和肾脏(显示病理区域)的脱氧Hb水平更高。我们还将测量一组其他生理特性，包括：网织红细胞、CBC和红细胞密度，以及在小鼠身上的转体运动能力(衡量运动协调性和耐力的指标)和尿液浓缩能力。最后，我们建议！精氨酸可以改善镰状细胞病的症状，并将在人类和小鼠身上通过测量流量和氧合来测试这一点，如本项目所述和 镰状细胞病项目中的精氨酸补充。我们的长期目标是证明这些技术可以用于镰状细胞病患者的病理评估和风险预测。

A primary feature of sickle cell disease are events resulting in low flow, poor perfusion, and blood and tissue hypoxia that are both pre-disposing to and the consequence of vaso-occlusion. We propose to test the limits of the hypothesis that the level of HbF, arginine in diet, and hydroxyurea all affect perfusion and blood oxygenation, albeit through different mechanisms. We will use a combination of Magnetic Resonance Imaging (MRI) and Near Infrared Spectroscopy (NIRS) to measure blood oxygenation, perfusion, and blood volume in human sickle cell patients and our new sickle transgenic mice that we have developed and characterized. At the onset of the grant period, our new Magnetic Resonance Research Center will have been in operation for more than 18 months with state-of-the-art 4 Tesla human and 9.4 Tesla animal systems. We have generated mice expressing exclusively human sickle hemoglobin with three levels of HbF using our previously described sickle constructs, mouse alpha- and beta-globin-knockouts, and three different human gamma-transgenes. We find that, progressive increase in HbF from <3% to 20% to 40% correlated with progressive increase in hematocrit (22% to 34% to 40%), a progressive decrease in reticulocyte count (fi'om 60% to 30% to 13%), and an increase in lifespan (from 45 to 194 to 368 days). Using BOLD-MRI or blood level oxygenation dependent magnetic resonance imaging and T2 mapping, we have demonstrated that transgenic mice expressing high levels of human and beta-s-globin have higher levels of deoxy Hb in brain, liver, and kidney, (areas showing pathology) compared to control mice. We also will measure a battery of other physiological properties including: reticulocytes, CBC, and red cell density, and, in the mice, rotorod performance (a measure of motor co-ordination and stamina) and urine concentrating ability. Finally, we propose !that arginine may ameliorate the symptoms of sickle cell disease and will test this in humans and mice by measurement of flow and oxygenation as described in this Project and transport measurements described in the Arginine Supplementation in Sickle Cell Disease Project. Our long range goal is to demonstrate that these technologies can used for evaluation of pathology and prediction of risk in sickle cell disease patients.