Additive-free hydrothermal leaching method with low environmental burden for screening of strontium in soil.

In this work, hydrothermal leaching was applied to simulated soils (clay minerals vermiculite, montmorillonite, and kaolinite) and actual soils (Terunuma, Japan) to generate organic acids with the objective to develop an additive-free screening method for determination of Sr in soil. Stable strontium (SrCl2) was adsorbed onto soils for the study, and ten organic acids (citric, L(+)-tartaric, succinic, oxalic, pyruvic, formic, glycolic, lactic, acetic, and propionic) were evaluated for leaching Sr from simulated soils under hydrothermal conditions (120 °C to 200 °C) at concentrations up to 0.3 M. For strontium-adsorbed vermiculite (Sr-V), 0.1 M citric acid was found to be effective for leaching Sr at 150 °C and 1 h treatment time. Based on these results, the formation of organic acids from organic matter in Terunuma soil was studied. Hydrothermal treatment of Terunuma soil produced a maximum amount of organic acids at 200 °C and 0.5 h reaction time. To confirm the possibility for leaching of Sr from Terunuma soil, strontium-adsorbed Terunuma soil (Sr-S) was studied. For Sr-S, hydrothermal treatment at 200 °C for 0.5 h reaction time allowed 40% of the Sr to be leached at room temperature, thus demonstrating an additive-free method for screening of Sr in soil. The additive-free hydrothermal leaching method avoids calcination of solids in the first step of chemical analysis and has application to both routine monitoring of metals in soils and to emergency situations.

Supercritical water pretreatment method for analysis of strontium and uranium in soil (Andosols).

Hydrothermal pretreatment of soils (Andosols) from Ibaraki prefecture (Japan) was used to improve methods for monitoring radioactive Sr and U. Calcined samples were pretreated with subcritical or supercritical water (SCW) followed by extraction with 0.5 M HNO3 solutions. With SCW pretreatment, recoveries of Sr and U were 70% and 40%, respectively. Experimental recoveries obtained can be described by a linear relationship in water density. The proposed method is robust and can lower environmental burden of routine analytical protocols.

Distribution and settling behavior of americium-241 in the tropical East Pacific.

The distribution of the anthropogenic radionuclide 241Am, a decay product of 241Pu discharged from atmospheric tests of nuclear weapons, was investigated to resolve its horizontal and vertical migration in the Tropical East Pacific. We analyzed 241Am concentrations in seawater samples collected in 2003. On comparing the 241Am concentrations with the previously determined concentrations of 239+240Pu in the same samples, the vertical profiles of 241Am were found to be similar to those of 239+240Pu. At some stations, the maximum concentration of 241Am occurred 100-200 m deeper than that of 239+240Pu. The 241Am/239+240Pu ratios in the North Pacific and South Pacific were comparable to one another, and were the typical ratio for the Pacific. The 241Am distribution was influenced by the water mass at depths below 400 m. The 241Am data support the view there is a current flowing at depths of 400-3000 m from the North Pacific through the Equator to the South Pacific. In addition, the 241Am vertical profile was explained by using a 1-D scavenging model that considers the decay of 241Pu and adsorption and scavenging by suspended particles. The different depths for the maximum concentrations of 241Am and 239+240Pu observed at some stations were well explained by the model and by the distribution of CaCO3 particles. The residence time of 241Am in the Pacific was also estimated by using the model.

Reducing radiation exposure during atrial fibrillation ablation using lectures to promote awareness.

Objective: Recently, concern has increased regarding the hazards of radiation exposure in patients and laboratory staff. Since the numbers of complex catheter ablations (CA) performed, duration of procedure times, and need for multiple sessions have increased, radiation exposure during each session needs to be minimised. Our study aimed to assess the impact of awareness on radiation exposure during CA for atrial fibrillation (AF). Methods: Mini-course lectures was delivered to the physicians and staff in the electrophysiology division. Its effect on the fluoroscopic time and radiation dose during AF ablation before (Group I, n=70), shortly after (Group II: n=70) and remotely after the mini-lecture (Group III, n=70) were evaluated. Patient demographics, preoperative testing and procedural parameters were collected. Results: The fluoroscopic time significantly reduced after the lecture (Group I and II: 25.1±10.0 and 15.1±7.3 min, respectively (p<0.0001)), and remained so in Group III (13.0±5.4 min), despite the increase in the number of persistent AFs. The radiation dose also significantly reduced (Groups I, II, III: 295.0±263.0, 109.6±103.5 and 110.1±89.6 mGy, respectively (p<0.0001)). Conclusion: Awareness on radiation exposure led to a significant reduction in fluoroscopic time and radiation dose during CA for AF, the effect of which persisted even to remote periods following the procedure.

Idiopathic Ventricular Arrhythmia Ablation Using Non-Fluoroscopic Catheter Visualization System.

A novel, sensor-based, electromagnetic, non-fluoroscopic catheter visualization (NFCV) system shows tracked catheters directly on pre-acquired fluoroscopy or cine loops. We aimed to evaluate the effectiveness of this system in the setting of catheter ablation for idiopathic premature ventricular contractions/ventricular tachycardia (i-PVC/VT).A total of 30 i-PVC/VT ablation procedures were performed using the NFCV system in conjunction with three-dimensional electroanatomic mapping system (3D-EMS) between January 2013 and April 2017. At the beginning of the procedure, cine loops of right and left anterior oblique views were obtained and replayed for subsequent mapping and ablation. Right ventriculography, aortography, or coronary angiography was performed, depending on the chamber of interest. We reviewed procedural parameters, comparing with the i-PVC/VT ablation procedure using conventional fluoroscopy (CvF) system (pre-, and post-NFCV implementation; 20 and 11 cases, respectively).I-PVC/VTs were successfully eliminated in 26 patients (87%) in the NFCV group and in 26 (84%) in the CvF group (P = 1.000). The procedure time in the NFCV group was comparable to that in the CvF group (119.8 versus 125.0 minutes, respectively, P = 0.868); the total fluoroscopy time was significantly shorter in the NFCV group (3.3 versus 16.6 minutes, P < 0.001). One patient in the CvF group experienced cardiac tamponade, requiring pericardial drainage. No major complications were encountered in the NFCV group.NFCV system, in conjunction with 3D-EMS, was safe and feasible for i-PVC/VT mapping and ablation. The system contributed to dramatically reduced fluoroscopy time, compared with CvF.

Nocturnal Hypoxemia, But Not Sleep Apnea, Is Associated With a Poor Prognosis in Patients With Pulmonary Arterial Hypertension.

BACKGROUND: Sleep apnea (SA) can cause repeated nocturnal arterial oxygen desaturation and result in acute increase in pulmonary arterial pressure (PAP). The presence of SA is associated with a poor prognosis in patients with chronic left-sided heart failure, but little is known for patients with pulmonary arterial hypertension (PAH). Methods and Results: We enrolled 151 patients with PAH (44±16 years old, male/female=37/114). They were all in the Nice Classification group 1 (idiopathic PAH/associated PAH=52/48%, mean PAP of 46±16 mmHg). They underwent right-heart catheterization and a sleep study with simplified polysomnography. Averaged percutaneous oxygen saturation (SpO2) during sleep was measured and an apnea-hypopnea index >5 was defined as SA. SA was noted in 58 patients (obstructive SA/central SA: 29/29). Over an average follow-up of 1,170±763 days, 32 patients died. By Kaplan-Meier analysis, there was no significant difference in deaths of patients with and without SA (χ2=2.82, P=0.093). On the other hand, the mortality in patients with lower averaged SpO2 was significantly higher than in those with higher averaged SpO2 (χ2=14.7, P<0.001) and that was the only independent variable related to death in multivariate Cox proportional hazards analysis. CONCLUSIONS: SA in patients with PAH was not associated with worse prognosis, unlike left ventricular heart failure, but nocturnal hypoxemia was related to poor prognosis.

Elongated ascending aorta predicts a short distance between his-bundle potential recording site and coronary sinus ostium.

BACKGROUND: When performing catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT), it can be difficult to maintain a safe distance from the His recording site to avoid AV block in patients with a short distance between this recording site to the coronary sinus (CS) ostium (small triangle of Koch [TOK]). In this study, we sought to identify parameters predicting small TOK and test these parameters in patients undergoing AVNRT catheter ablation. METHODS: Twenty-eight patients who underwent catheter ablation of atrial fibrillation using a three-dimensional (3D) electroanatomical mapping system (EAM) with computed tomography (CT) merge (23 males; mean age, 65.8±12.1 years) were included. The shortest distance between the CS ostium and His recording sites (His-CSd) was measured on the EAM. Aortic (Ao) unfolding in chest X-ray scan, Ao angle to the LV, Ao length, Ao to the right ventricular distance, size of the Valsalva in the CT scan, and parameters of echocardiogram were evaluated. The identified parameters were subsequently tested as predictors for small TOK in patients undergoing AVNRT ablation. RESULTS: The size of TOK was associated with Ao length (r = -0.70, p<0.01), left ventricular end-systolic dimension (LVDs) (r = -0.51, p<0.01), and Ao unfolding. In patients with AVNRT, only Ao unfolding predicted a smaller TOK. CONCLUSIONS: Small TOK was associated with longer Ao, larger LVDs, and Ao unfolding. Of these, Ao unfolding was associated with smaller TOK in patients with AVNRT.

Outcomes of single- or dual-chamber implantable cardioverter defibrillator systems in Japanese patients.

BACKGROUND: There are no criteria for selecting single- or dual-chamber implantable cardioverter defibrillators (ICDs) in patients without a pacing indication. Recent reports showed no benefit of the dual-chamber system despite its preference in the United States. As data on ICD selection and respective outcomes in Japanese patients are scarce, we investigated trends regarding single- and dual-chamber ICD usage in Japan. METHODS: Data from a total of 205 ICD recipients with structural heart disease (median age, 63 years) in two Japanese university hospitals were reviewed. Patients with bradycardia with a pacing indication and permanent atrial fibrillation at implantation were excluded. RESULTS: Single- and dual-chamber ICDs were implanted in 36 (18%) and 169 (82%) patients, respectively. Non-ischemic cardiomyopathy dominated both groups. Seventeen dual-chamber patients developed atrial pacing-dependency over 4.5 years, and it developed immediately after implantation in 14. Although preoperative testing showed no sign of bradycardia in these patients, their pacing rate was set higher than it was in patients who were pacing-independent (61 vs. 46 paces per min, p<0.01). Two single-chamber patients (5%) underwent atrial lead insertion. While inappropriate shock equally occurred in both groups (7 vs. 21 patients, single- vs. dual-chamber, P=0.285), device-related infection occurred only in dual-chamber patients (0 vs. 9 patients, P=0.155). No differences in death or heart failure hospitalization were observed between groups. CONCLUSIONS: Dual-chamber ICDs were four-fold more common in Japanese patients without a pacing indication. No benefit over single-chamber ICD was observed. Newly developed atrial pacing-dependency seemed to be limited and could have been overestimated due to higher pacing rate settings in dual-chamber patients.

Antigen signal strength during priming determines effector CD4 T cell function and antigen sensitivity during influenza virus challenge.

TCR signal strength during priming is a key determinant of CD4 T cell activation, but its impact on effector CD4 T functions in vivo remains unclear. In this study, we compare the functionality of CD4 T cell responses induced by peptides displaying varying binding half-lives with MHC class II before and after influenza virus infection. Although significant quantitative and qualitative differences in CD4 T cell responses were observed before infection between mice vaccinated with low- or high-stability peptides, both mice mounted robust early Th1 effector cytokine responses upon influenza challenge. However, only effector CD4 T cells induced by low-stability peptides proliferated and produced IL-17A after influenza challenge. In contrast, effector T cells elicited by higher-stability peptides displayed a terminally differentiated phenotype and divided poorly. This defective proliferation was T cell intrinsic but could not be attributed to a reduced expression of lymph node homing receptors. Instead, we found that CD4 T cells stimulated with higher-stability peptides exhibited decreased responsiveness to low levels of Ag presentation. Our study reveals the critical role of TCR signal strength during priming for the function and Ag sensitivity of effector CD4 T cells during viral challenge.

Retention of potentially mobile radiocesium in forest surface soils affected by the Fukushima nuclear accident.

The fate of (137)Cs derived from the Fukushima nuclear accident fallout and associated radiological hazards are largely dependent on its mobility in the surface soils of forest ecosystems. Thus, we quantified microbial and adsorptive retentions of (137)Cs in forest surface (0-3 cm) soils. The K(2)SO(4) extraction process liberated 2.1%-12.8% of the total (137)Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher (137)Cs extractability. Microbial biomass was observed in all of the soils. However, the (137)Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout (137)Cs. The results indicate that uptake of (137)Cs by soil microorganisms is less important for retention of potentially mobile (137)Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components.

Anthropogenic Pu distribution in Tropical East Pacific.

The geographical distribution of the anthropogenic radionuclides (238)Pu and (239+240)Pu in the Tropical East Pacific in 2003 was studied from the viewpoint of material migration. We measured the contents of Pu isotopes in seawater and in sediment from the sea bottom. The distributions of Pu isotopes, together with those of coexisting nitrate and phosphate species and dissolved oxygen, are discussed in relation to the potential temperature and potential density (sigma-θ). The Pu contents in sediment samples were compared with those in the seawater. Horizontal migration across the Equator from north to south was investigated at depths down to ~800m in the eastern Pacific. The Pu distribution at 0-400m correlated well with the distribution of potential temperature. Maximum Pu levels were observed in the subsurface layer at 600-800m, corresponding to the depth where sigma-θ≈27.0. It is suggested that the Pu distribution depends on the structure of the water mass and the particular temperature and salinity. The water column/sediment column inventory ratio and the vertical distribution of Pu may reflect the efficiency of scavenging in the relevant water areas.

Peptide-MHC class II complex stability governs CD4 T cell clonal selection.

The clonal composition of the T cell response can affect its ability to mediate infection control or to induce autoimmunity, but the mechanisms regulating the responding TCR repertoire remain poorly defined. In this study, we immunized mice with wild-type or mutated peptides displaying varying binding half-lives with MHC class II molecules to measure the impact of peptide-MHC class II stability on the clonal composition of the CD4 T cell response. We found that, although all peptides elicited similar T cell response size on immunization, the clonotypic diversity of the CD4 T cell response correlated directly with the half-life of the immunizing peptide. Peptides with short half-lives focused CD4 T cell response toward high-affinity clonotypes expressing restricted public TCR, whereas peptides with longer half-lives broadened CD4 T cell response by recruiting lower-affinity clonotypes expressing more diverse TCR. Peptides with longer half-lives did not cause the elimination of high-affinity clonotypes, and at a low dose, they also skewed CD4 T cell response toward higher-affinity clonotypes. Taken collectively, our results suggest the half-life of peptide-MHC class II complexes is the primary parameter that dictates the clonotypic diversity of the responding CD4 T cell compartment.