Size Calcium Research Articles

Paravalvular leak prediction after transcatheter aortic valve replacement with self-expandable prosthesis based on quantitative aortic calcification analysis.

Paravalvular leak (PVL) is one of the most common complications of transcatheter aortic valve replacement (TAVR) and affects short- and long-term outcomes. The aim of this study was to identify the computed tomography (CT) imaging biomarkers that allow PVL after TAVR to be predicted. Patients were included who had severe aortic valve stenosis, had undergone TAVR with a self-expanding valve, and had undergone a pre-procedural CT scan. Data on baseline characteristics, procedural and long-term outcomes were collected retrospectively. We used MATLAB software with a self-developed algorithm for CT scan analysis and found parameters that quantified aortic valve calcifications (AVC) in detail. Fifty patients were included. The identified CT-derived parameters included AVC size, volume, thickness and density, as well as calcium radial distribution. The volume of the largest calcium block, calcium perimeter and calcium size (assessed by Feret's diameter) showed a strong association with PVL occurrence after TAVR (P=0.012, P=0.001 and P=0.045, respectively). The prognostic model showed that a 10 mm2 increase in the local AVC amount in each valve section was associated with a 9.8% (95% CI: 2-18%; P=0.019) increase in the risk of PVL occurrence in the corresponding area after TAVR. ROC analysis revealed that the cut-off point of the AVC area was 96.5 mm2 in the polar coordinate system presentation. Kaplan-Meier curves showed worse PVL-free survival in patients with more than 96.5 mm2 of calcium area (P=0.013; log-rank). Quantitative AVC assessment for PVL prediction may play an important role in screening before TAVR. In future, the use of quantitative AVC assessment as an imaging biomarker in TAVR candidates and the creation and extension of an online database containing quantitative AVC parameters may help to identify high PVL risk patients.

Extracorporeal Shock Wave Lithotripsy Treatment for Renal and Ureteral Stones in Duhok City

The present study reports the results of extracorporeal shock-wave lithotripsy treatment for renal and ureteral stones in Duhok city. The data were collected from the center of breakdown kidney stones in Duhok hospital. There were a total of 40 patients (25 males and 15 females) aged from 20 to 60 years old. The patients harboring (23 renal and 17 ureteral) stones of size ranged from 7.5 to 20 mm. Almost stones are of average size 9 mm and composed of uric acid, calcium and cystine stones. The study has been carried out by taking into consideration the parameters (type, sizes, composition and location of stone as well as region and ages of patients, also power, number of shock wave and sessions). The results show that the stones size increases according to increasing ages of patients (male and female) for uric acid ureter stone and calcium (renal, ureter) stones. Also (renal, ureter) stone size for patients aged from 20 to 30 years old increases from the minimum value for phosphate to maximum value for cystine stones, while for patients aged from 40 to 60 years old, the minimum size is obtained for calcium oxalate and the maximum size for calcium only. On the other hand, for uric acid stones of average size 9 mm, number of shock wave and sessions as well as the power required to breakdown the stones decrease nearly exponentially according to enhancing patients’ ages. At the same time, it's found that for adult patients (20 - 30 years old), number of sessions and the power of shock wave decrease also according to increasing size of calcium and cystine stones. Contrary to that, for the same ages and renal, uretral cysteine stones number of shock wave needed to breakdown large stones will be increased.

The microstructure of multi-layer nc-Ca films on different substrates

Multi-layer nanocrystalline Ca (nc-Ca) films were prepared by vacuum evaporation method, using three different materials as the substrate, namely CaF2(111), Si(100), and Si(111). The films can be stored in the air for a long time, and there was no obvious shedding phenomenon at room temperature. Nc-ca thin films on different substrates were characterised by XRD analysis, showed (111) preferred orientation. On CaF2(111), Si(100) and Si(111) substrates, the average grain size of calcium are 36.8 nm, 43.9 nm and 45.2 nm, respectively. By SEM analysis, there was a better surface morphology of the films on the CaF2(111) substrate.

Complex competition between ferromagnetism and antiferromagnetism in the CMR manganites Pr1−x Ca x MnO3

The systematic investigation of the magnetic susceptibility of the CMR manganites Pr1−x Ca x MnO3 versus temperature has been performed for 0.25 ≤ x ≤ 0.50. Due to the similar size of calcium and praseodymium, these results show the important role of the mixed valence of manganese upon the complex magnetic behaviour of these compounds. They demonstrate that the appearance of antiferromagnetism coincides with charge ordering, T N = T CO varying with x, from 250K for x = 0.50 to 225K for x = 0.35. A strong competition between ferromagnetism and antiferromagnetism is observed for 0.35 ≤ x 170 K) and going through canted antiferromagnetic or weak ferromagnetic states for intermediate temperatures (70 K < T < 170 K). For 0.25 ≤ x ≤ 0.30, a strong ferromagnetic state is observed for 95 K ≤ T ≤ 150 K, with a transition to a spin glass like state below 95–110 K.