ABSTRACT
Objective@#To analyze the normal value of the iodine content in the left ventricular myocardium of healthy subjects and to observe if there is a segmental differences on iodine distribution by using the second generation dual-source dual-energy computed tomography myocardial first perfusion imaging.@*Methods@#In this retrospective study, 42 healthy subjects, who admitted to our department between January to June 2016, with normal second generation dual-source dual-energy computed tomography and coronary CT angioghphy (CTA), electrocardiogram (ECG) results, normal cardiac, hepatic, renal function, normal myocardial enzymes results were enrolled, data from 38 out of 42 subjects with satisfactory image quality were analyzed using Siemens Dual Energy-Heart PBV image processing software.In accordance with the standards of the American Heart Association myocardial 17 fractionation method, content of iodine was measured at different segmental left ventricular myocardium and aorta (left coronary artery from the opening level). The standardized containing iodine value (nIC) was calculated.@*Results@#The iodine content of left ventricular myocardium in normal subjects was 3.1-7.8 mg/ml.The nIC of myocardium from 1st to 17th segments was 0.28±0.06, 0.31±0.07, 0.30±0.07, 0.30±0.04, 0.28±0.04, 0.29±0.05, 0.29±0.01, 0.30±0.07, 0.31±0.07, 0.27±0.06, 0.28±0.08, 0.28±0.07, 0.29±0.08, 0.31±0.07, 0.27±0.06, 0.29±0.06 and 0.21±0.07, respectively.The nIC of the 17th segment was the lowest and was significantly lower than in other segments (all P<0.05), the nIC was similar among the rest 16 segments (all P>0.05).@*Conclusion@#The normal iodine content range in left ventricle myocardium is 3.1-7.8 mg/ml, and the lowest iodine content is detected in the apex and which is significantly lower than the other left ventricular segments.
ABSTRACT
Purpose To evaluate the clinical value of triple-rule-out (TRO) computed tomographic angiography using adaptive prospective ECG triggering for chest pain patients.Materials and Methods Sixty patients with chest pain were prospectively collected and randomly divided into group A and group B:group A (n=30) performed prospectively gated axial scan and group B (n=30) performed retrospectively gated helical scan.The vascular density,noise and muscle density of the vessels including aorta,pulmonary artery,coronary artery between the two groups were measured and analyzed.The vascular density/noise ratio,contrast noise ratio and effective dose (ED) between the two groups were calculated.The image quality and scanning radiation dose were compared between the two groups.Results There was no significant difference in the image quality of aorta,pulmonary artery and coronary artery between group A and group B (P＞0.05).The ED in group A was lower than that in group B [(5.90±2.10) mSv vs (11.31 ± 2.12) mSv,P＜0.01].Conclusion The technique of TRO computed tomographic angiography triggered by adaptive prospective ECG can significantly reduce the radiation dose while ensuring image quality.
ABSTRACT
Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.