Extended X-ray absorption fine structure spectroscopy measurements and ab initio molecular dynamics simulations reveal the hydration structure of the radium(II) ion.

Radium is refocused from the viewpoint of an environmental pollutant and cancer therapy using alpha particles, where it mainly exists as a hydrated ion. We investigated the radium hydration structure and the dynamics of water molecules by extended X-ray absorption fine structure (EXAFS) spectroscopy and ab initio molecular dynamics (AIMD) simulation. The EXAFS experiment showed that the coordination number and average distance between radium ion and the oxygen atoms in the first hydration shell are 9.2 ± 1.9 and 2.87 ± 0.06 Å, respectively. They are consistent with those obtained from the AIMD simulations, 8.4 and 2.88 Å. The AIMD simulations also revealed that the water molecules in the first hydration shell of radium are less structured and more mobile than those of barium, which is an analogous element of radium. Our results indicate that radium can be more labile than barium in terms of interactions with water.

Marking actinides for separation: Resonance-enhanced multiphoton charge transfer in actinide complexes.

Precise separation and purification of f-block elements are important and challenging especially for the reduction of nuclear waste and the recycling of rare metals but are practically difficult mainly because of their chemical similarity. A promising way to overcome this difficulty is controlling their oxidation state by nonchemical processes. Here, we show resonance-enhanced multiphoton charge transfer in actinide complexes, which leads to element-specific control of their oxidation states owing to the distinct electronic spectra arising from resonant transitions between f orbitals. We observed oxidation of trivalent americium in nitric acid. In addition, we found that the coordination of nitrates is essential for promoting the oxidation reaction, which is the first finding ever relevant to the primary process of photoexcitation via resonant transitions of f-block elements. The resonance-enhanced photochemical process could be used in the nuclear waste management, as it would facilitate the mutual separation of actinides, such as americium and curium.

Investigation of thoracic four-dimensional CT-based dimension reduction technique for extracting the robust radiomic features.

Robust feature selection in radiomic analysis is often implemented using the RIDER test-retest datasets. However, the CT Protocol between the facility and test-retest datasets are different. Therefore, we investigated possibility to select robust features using thoracic four-dimensional CT (4D-CT) scans that are available from patients receiving radiation therapy. In 4D-CT datasets of 14 lung cancer patients who underwent stereotactic body radiotherapy (SBRT) and 14 test-retest datasets of non-small cell lung cancer (NSCLC), 1170 radiomic features (shape: n = 16, statistics: n = 32, texture: n = 1122) were extracted. A concordance correlation coefficient (CCC) > 0.85 was used to select robust features. We compared the robust features in various 4D-CT group with those in test-retest. The total number of robust features was a range between 846/1170 (72%) and 970/1170 (83%) in all 4D-CT groups with three breathing phases (40%-60%); however, that was a range between 44/1170 (4%) and 476/1170 (41%) in all 4D-CT groups with 10 breathing phases. In test-retest, the total number of robust features was 967/1170 (83%); thus, the number of robust features in 4D-CT was almost equal to that in test-retest by using 40-60% breathing phases. In 4D-CT, respiratory motion is a factor that greatly affects the robustness of features, thus by using only 40-60% breathing phases, excessive dimension reduction will be able to be prevented in any 4D-CT datasets, and select robust features suitable for CT protocol of your own facility.

Dosage Adjustment of Dabigatran Etexilate Based on Creatinine Clearance in Patients With Cardioembolic Stroke or Atrial Fibrillation.

BACKGROUND: A recommendation for dosage adjustment of dabigatran etexilate, a prodrug of dabigatran, seems to be desirable based on creatinine clearance to avoid bleeding and stroke. METHODS: Outpatients and inpatients having a history of cardioembolic stroke or atrial fibrillation were included. After taking dabigatran etexilate orally (75-150 mg twice daily) for at least 1 week, plasma trough concentration (Ctrough, ng/mL) of dabigatran and creatinine clearance (CLcr, mL/min) of patients according to Cockcroft and Gault equation were determined. RESULTS: Among the 38 patients studied, Ctrough of dabigatran and CLcr were scattered in a range from 31.4 to 329.5 ng/mL and 15.4-133.4 mL/min, respectively. Temporal CLtotal (Temp-CLtotal) of dabigatran, estimated by dividing the daily absorbed amount of dabigatran etexilate with Ctrough of dabigatran, was linearly correlated with CLcr of patients (P = 0.0018). Based on the findings, the daily dose of dabigatran etexilate that provides Ctrough of dabigatran at approximately 70 ng/mL was estimated. CONCLUSIONS: A linear relationship was found between Temp-CLtotal of dabigatran and CLcr of patients. Depending on CLxr of patients, we recommend 4 different dosages of dabigatran etexilate to obtain Ctrough of dabigatran at approximately 70 ng/mL.

Interaction of magnesium oxide with gastric acid secretion inhibitors in clinical pharmacotherapy.

PURPOSE: Magnesium oxide (MgO), a short-term osmotic laxative, is converted into MgCl2 under acidic condition in the stomach and then Mg(HCO3)2 in the intestinal tract, where Mg(HCO3)2 induces the water exudation into the intestine. This indicates that the laxative effect of MgO could be attenuated under the suppressed gastric acid secretion. In this study, the possible interaction of MgO with gastric acid secretion inhibitors was evaluated by using electronic patient records of MgO dosage levels. METHODS: Defecation was controlled with MgO alone in some patients after colon surgery (n = 67) and after total gastric resection (n = 4). Some other patients were treated with a combination use of MgO and H2 receptor antagonist (H2RA) (n = 14) or proton pump inhibitor (PPI) (n = 27). The possible drug interaction of MgO with H2RA or PPI was evaluated by comparing dosage levels of MgO used in controlling defecation. RESULTS: In controlling defecation, the daily dosage levels of MgO in patients taking H2RA or PPI and patients with total gastric resection were significantly higher than those patients taking MgO alone after colon surgery. The ratios of good constipation control (controlled well at the dosing level of 1,000 mg MgO) in patients taking H2RA or PPI were significantly lower than that in patients treated with MgO alone. In an in vitro study, the solubility of MgO at pH 4.5 was quite low, as compared with that at pH 1.2. CONCLUSIONS: When patients received H2RA or PPI, the laxative effect of MgO is decreased possibly due to the low solubility of MgO at the higher gastric pH and less generation of MgCl2 and Mg(HCO3)2. Higher dosing level of MgO or another laxative should be used in patients taking H2RA or PPI, as well as the case of patients with total gastric resection.