Cesium-137 and 137Cs/133Cs atom ratios in marine zooplankton off the east coast of Japan during 2012-2020 following the Fukushima Dai-ichi nuclear power plant accident.

We measured the concentrations of cesium isotopes (133Cs, 134Cs, and 137Cs) in zooplankton samples collected in waters off the east coast of Japan from May 2015 to June 2020. By combining these data with those obtained previously from May 2012 to February 2015, we evaluated the long-term impacts of the Fukushima Dai-ichi Nuclear Power Plant accident on marine zooplankton. Relatively high 137Cs concentrations in zooplankton, exceeding 10 Bq/kg-dry weight, were sporadically observed until June 2016, regardless of year or station. After May-June 2017, 137Cs concentrations decreased to below 1 Bq/kg-dry at most stations, and by May 2020, concentrations were below 0.5 Bq/kg-dry except those off Fukushima Prefecture. Since the accident, the 137Cs/133Cs atom ratios of zooplankton samples were higher than those of ambient seawater until 2019, but in May-June 2020 the ratios matched those of seawater except off Fukushima Prefecture. Highly radioactive particles were not detected in zooplankton samples by autoradiography using imaging plates after May-June 2017, although they were before. Therefore, the persistence of elevated 137Cs/133Cs ratios in zooplankton relative to seawater for nine years after the accident was probably due to the incorporation of highly radioactive particles (cesium-bearing particles or clay-mineral aggregates with highly adsorbed radiocesium) onto/into zooplankton for several years after the accident. However, since at least May-June 2017, these elevated ratios have likely been caused by small highly radioactive particles (or larger particles disaggregated into small pieces) entering the ocean from land via rivers or directly discharged from the Fukushima Nuclear Power Plant. Microplastics enriched with radiocesium with higher 137Cs/133Cs ratios than seawater may have also contributed 137Cs to the zooplankton.

Occurrence of highly radioactive microparticles in the seafloor sediment from the pacific coast 35 km northeast of the Fukushima Daiichi nuclear power plant.

To understand the properties and significance of highly radioactive particles in the marine environment, we have examined seafloor sediment with a radioactivity of ∼1200 Bq/kg (dry weight; after decay correction to March 2011) collected 35 km northeast of the Fukushima Daiichi Nuclear Power Plant (FDNPP). Among the 697 highly radioactive particles separated from the sediment, two particles, D1-MAX and D1-MID, had a total Cs radioactivity of ∼56 and 0.67 Bq (after decay correction to March 2011), respectively. These particles were characterized with a variety of electron microscopic techniques, including transmission electron microscopy. The 134Cs/137Cs radioactivity ratio of D1-MAX, 1.04, was comparable to that calculated for Unit 2 or 3. D1-MAX consisted mainly of a Cs-rich microparticle (CsMP) with a silica glass matrix. The data clearly suggested that D1-MAX resulted from a molten core-concrete interaction during meltdowns. In contrast, D1-MID was an aggregate of plagioclase, quartz, anatase, and Fe-oxide nanoparticles as well as clay minerals, which had adsorbed soluble Cs. D1-MID was likely a terrestrial particle that had been transported by wind and/or ocean currents to a site 35 km from the FDNPP. The radioactive fractions of D1-MAX and D1-MID were 15% and 0.36%, respectively, of the total radioactivity in the bulk sediment. These highly radioactive particles have a great impact on the movement of radioactive Cs in the marine environment by carrying condensed Cs radioactivity with various colloidal and desorption properties depending on the host phase.

Blockade of PAR-1 Signaling Attenuates Cardiac Hypertrophy and Fibrosis in Renin-Overexpressing Hypertensive Mice.

Background Although PAR-1 (protease-activated receptor-1) exerts important functions in the pathophysiology of the cardiovascular system, the role of PAR-1 signaling in heart failure development remains largely unknown. We tested the hypothesis that PAR-1 signaling inhibition has protective effects on the progression of cardiac remodeling induced by chronic renin-angiotensin system activation using renin-overexpressing hypertensive (Ren-Tg) mice. Methods and Results We treated 12- to 16-week-old male wild-type (WT) mice and Ren-Tg mice with continuous subcutaneous infusion of the PAR-1 antagonist SCH79797 or vehicle for 4 weeks. The thicknesses of interventricular septum and the left ventricular posterior wall were greater in Ren-Tg mice than in WT mice, and SCH79797 treatment significantly decreased these thicknesses in Ren-Tg mice. The cardiac fibrosis area and monocyte/macrophage deposition were greater in Ren-Tg mice than in WT mice, and both conditions were attenuated by SCH79797 treatment. Cardiac mRNA expression levels of PAR-1, TNF-α (tumor necrosis factor-α), TGF-ß1 (transforming growth factor-ß1), and COL3A1 (collagen type 3 α1 chain) and the ratio of ß-myosin heavy chain (ß-MHC) to α-MHC were all greater in Ren-Tg mice than in WT mice; SCH79797 treatment attenuated these increases in Ren-Tg mice. Prothrombin fragment 1+2 concentration and factor Xa in plasma were greater in Ren-Tg mice than in WT mice, and both conditions were unaffected by SCH79797 treatment. In isolated cardiac fibroblasts, both thrombin and factor Xa enhanced ERK1/2 (extracellular signal-regulated kinase 1/2) phosphorylation, and SCH79797 pretreatment abolished this enhancement. Furthermore, gene expression of PAR-1, TGF-ß1, and COL3A1 were enhanced by factor Xa, and all were inhibited by SCH79797. Conclusions The results indicate that PAR-1 signaling is involved in cardiac remodeling induced by renin-angiotensin system activation, which may provide a novel therapeutic target for heart failure.

D-dimer and C-reactive Protein as Potential Biomarkers for Diagnosis of Trousseau's Syndrome in Patients with Cerebral Embolism.

BACKGROUND: Differentiating stroke due to Trousseau's syndrome from other types of cerebral embolism is challenging, especially in patients with occult cancer. The current study aimed to determine predicting factors and biomarkers of stroke due to Trousseau's syndrome. METHODS: This retrospective study comprised 496 consecutive patients with acute cerebral embolism, including 19, 85, 310, and, 82 patients with stroke due to Trousseau's syndrome, artery-to-artery embolism, cardioembolic stroke, and embolic stroke with undetermined source, respectively. All patients were evaluated within 72 hours of onset. The clinical characteristics, laboratory findings, and patterns on diffusion-weighted magnetic resonance imaging (DWI) were compared among the groups. RESULTS: Plasma D-dimer and C-reactive protein (CRP) levels were significantly higher in the Trousseau's syndrome than in the other causes of cerebral embolism. Multivariate analyses demonstrated that female sex, multiple lesions on DWI, high D-dimer and CRP levels, and low platelet and low brain natriuretic peptide levels were independent predictors that could distinguish Trousseau's syndrome from the other causes of cerebral embolism. The cutoff values of D-dimer and CRP to identify stroke due to Trousseau's syndrome was 2.68 µg/mL fibrinogen equivalent units and .29 mg/dL, respectively. CONCLUSIONS: The elevated D-dimer and CRP levels on admission in addition to specific clinical features may be useful for diagnosis of Trousseau's syndrome in patients with cerebral embolism.

The contribution of 137Cs export flux from the Tone River Japan to the marine environment.

The contribution of 137Cs transport to the marine environment via the Tone River, Japan was investigated. This river has the largest discharge among rivers on the North Pacific side of eastern Japan. The sampling site was located upstream near the river mouth and dissolved and particulate 137Cs in the river water was measured during 2014-2015, three years after the Tokyo Electric Power Corporation Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Annual fluxes of total (dissolved and particulate) 137Cs with considering desorption of 137Cs from riverine particles by change of salinity from the Tone River were similar in both years (78-107 × 109 Bq/y), indicating that about 0.03-0.06% of the estimated total amount of 137Cs deposited in the catchment (1.9-2.8 × 1014 Bq) was transported to the marine environment each year. Although the annual flux was about one order of magnitude lower than the daily direct discharge into the ocean from the FDNPP (800 × 109 Bq/y) during the corresponding period, continuous monitoring of rivers in the southern coastal area of east Japan on the North Pacific side are needed for the effect of 137Cs release via the rivers in the Kanto area over the long-term.

Novel Electrocardiographic Criteria for the Diagnosis of Left Ventricular Hypertrophy in the Japanese General Population.

Although there are several diagnostic criteria for left ventricular hypertrophy (LVH), their sensitivity remains low. A recent study reported that the sum of the amplitude of the deepest S wave in any lead (SD) and the S wave in lead V4 (SV4) (SD + SV4) improved sensitivity compared with commonly used criteria. To test whether this new formula improves sensitivity in the Japanese general population, we analyzed 12-lead electrocardiograms for Japanese residents participating in the Iwaki Health Promotion Project (n = 866). Left ventricular mass was calculated by echocardiography, indicating that 156 (18%) of the study population had LVH. In receiver operating characteristic analyses, the sum of the R wave in limb lead Ι (RLΙ) and the S wave in V4 (SV4) (RLΙ + SV4) showed a higher area under the curve (AUC = 0.76) than the Sokolow-Lyon voltage criteria (0.61) and the SD + SV4 criteria (0.63), and almost the same AUC as the Cornell voltage criteria (0.74) and the Cornell product criteria (0.76). The validation study also showed similar results. The cutoff values of RLΙ + SV4 criteria were ≥1.6 mV in men and ≥1.4 mV in women with a sensitivity of 39% and a specificity of 89%, whereas the sensitivity and specificity calculated based on SD + SV4 criteria were 21% and 94%, respectively. Thus, the diagnostic criterion of RLΙ + SV4 seems to be more useful than the previous criteria for diagnosing LVH in the Japanese general population.

Radiocesium in the swash zones off the coast of the Japan Sea.

Radiocesium concentrations were measured in seawater and sediment samples collected in the swash zones in Ishikawa and Niigata prefectures, off the coast of Japan Sea opposite to the side where TEPCO Fukushima dai-ichi Nuclear Power Plant (FDNPP) is located in September 2016 and August 2017, five to six years after the accident. Cs-134 in the seawater samples was detected, suggesting the intrusion of FDNPP-derived radiocesium in both swash zones. FDNPP-derived radiocesium was appeared to be transported by the Tsushima Warm Current. In the surface sediments only 137Cs was detected during the sampling period. We could not find out the presence of the FDNPP-derived radiocesium in the corresponding sediment on the swash zones; however, detected radiocesium in those sediments was assumed to be influenced by 137Cs of FDNPP-derived radiocesium little for Ishikawa area and some for Niigata area.

Temporal variation of cesium isotope concentrations and atom ratios in zooplankton in the Pacific off the east coast of Japan.

After the Fukushima Daiichi Nuclear Power Plant accident in March 2011, concentrations of cesium isotopes (133Cs, 134Cs, and 137Cs) were measured in zooplankton collected in the Pacific off the east coast of Japan from May 2012 to February 2015. The time series of the data exhibited sporadic 137Cs concentration peaks in zooplankton. In addition, the atom ratio of 137Cs/133Cs in zooplankton was consistently high compared to that in ambient seawater throughout the sampling period. These phenomena cannot be explained fully by the bioaccumulation of 137Cs in zooplankton via ambient seawater intake, the inclusion of resuspended sediment in the plankton sample, or the taxonomic composition of the plankton. Autoradiography revealed highly radioactive particles within zooplankton samples, which could be the main factor underlying the sporadic appearance of high 137Cs concentrations in zooplankton as well as the higher ratio of 137Cs/133Cs in zooplankton than in seawater.