Fukushima-derived radiocesium in the western subarctic area of the North Pacific Ocean, Bering Sea, and Arctic Ocean in 2019 and 2020.

We measured dissolved radiocesium (134Cs and 137Cs) in surface seawater collected in the western subarctic area of the North Pacific Ocean, Bering Sea, and Arctic Ocean in 2019 and 2020. The radiocesium released from the accident of the Fukushima Dai-ichi nuclear power plant (FNPP1) in 2011 was still observed in these areas (∼2 Bq m-3 decay-corrected to the date of the accident). In 2019/2020, the FNPP1-derived radiocesium concentrations in the Bering Sea and the Chukchi Sea, which is a marginal sea of the Arctic Ocean connecting the Bering Sea to the Arctic Ocean, were within the range of those observed in 2017/2018. On the other hand, the FNPP1-derived radiocesium was detected in the Arctic Ocean farther north of the Chukchi Sea in 2019/2020 for the first time. This was probably derived from the long-range transport of the FNPP1-derived radiocesium from the North Pacific coastal area of Japan to the Arctic Ocean through the Bering Sea during the past decade. The transport of the FNPP1-derived radiocesium from the Bering Sea to the western subarctic area in 2019/2020 is not clear, which implies the retainment of the FNPP1-derived radiocesium within the Bering Sea.

Toward sustainable meteorological profiling in polar regions: Case studies using an inexpensive UAS on measuring lower boundary layers with quality of radiosondes.

This study assessed the possibility of producing profiles of atmospheric parameters, including aerosol number concentration, using observations obtained by a conventional low-cost small rotary-wing Unmanned Aircraft Systems (UAS). A radiation shield for the meteorological sensor was developed to reduce the effects from heat exhaust from both the rotors and the body of the UAS and from solar radiation. Field experiments in northern Japan during winter confirmed that the continuous UAS-derived meteorological data obtained in the lower boundary layer were of quality equivalent to that of radiosonde observations in a cold environment (<- 20 °C), that is, better than other meteorological rotary-wing UASs. The continuous profiling of aerosols also demonstrated the capability for monitoring air quality below a very strong inversion layer during winter. Quality-controlled UAS meteorological profiles would be a potential observation data source for skillful numerical weather prediction, particularly in data-sparse regions such as the Arctic and Antarctic, contributing to the sustainable polar observing network.

Antarctic Peninsula warm winters influenced by Tasman Sea temperatures.

The Antarctic Peninsula of West Antarctica was one of the most rapidly warming regions on the Earth during the second half of the 20th century. Changes in the atmospheric circulation associated with remote tropical climate variabilities have been considered as leading drivers of the change in surface conditions in the region. However, the impacts of climate variabilities over the mid-latitudes of the Southern Hemisphere on this Antarctic warming have yet to be quantified. Here, through observation analysis and model experiments, we reveal that increases in winter sea surface temperature (SST) in the Tasman Sea modify Southern Ocean storm tracks. This, in turn, induces warming over the Antarctic Peninsula via planetary waves triggered in the Tasman Sea. We show that atmospheric response to SST warming over the Tasman Sea, even in the absence of anomalous tropical SST forcing, deepens the Amundsen Sea Low, leading to warm advection over the Antarctic Peninsula.

Impact on predictability of tropical and mid-latitude cyclones by extra Arctic observations.

Recent research has demonstrated that additional winter radiosonde observations in Arctic regions enhance the predictability of mid-latitude weather extremes by reducing uncertainty in the flow of localised tropopause polar vortices. The impacts of additional Arctic observations during summer are usually confined to high latitudes and they are difficult to realize at mid-latitudes because of the limited scale of localised tropopause polar vortices. However, in certain climatic states, the jet stream can intrude remarkably into the mid-latitudes, even in summer; thus, additional Arctic observations might improve analysis validity and forecast skill for summer atmospheric circulations over the Northern Hemisphere. This study examined such cases that occurred in 2016 by focusing on the prediction of the intensity and track of tropical cyclones (TCs) over the North Atlantic and North Pacific, because TCs are representative of extreme weather in summer. The predictabilities of three TCs were found influenced by additional Arctic observations. Comparisons with ensemble reanalysis data revealed that large errors propagate from the data-sparse Arctic into the mid-latitudes, together with high-potential-vorticity air. Ensemble forecast experiments with different reanalysis data confirmed that additional Arctic observations sometimes improve the initial conditions of upper-level troposphere circulations.

Correlated Increase of High Ocean Waves and Winds in the Ice-Free Waters of the Arctic Ocean.

The long-term trend of extreme ocean waves in the emerging ice-free waters of the summer Arctic is studied using ERA-Interim wave reanalysis, with validation by two drifting wave buoys deployed in summer 2016. The 38-year-long reanalysis dataset reveals an increase in the expected largest significant wave height from 2.3 m to 3.1 m in the ice-free water from the Laptev to the Beaufort Seas during October. The trend is highly correlated with the expected increase in highest wind speed from 12.0 m/s to 14.2 m/s over the ice-free ocean, and less so with the extent of the ice-free water. Since the storms in this area did not strengthen throughout the analysis period, the increase in the expected largest significant wave height follows from the enhanced probability of storms in ice-free waters, which is pertinent to the estimation of extreme sea conditions along the Northern Sea Route.

Elevated Expression of Dkk-1 by Glucocorticoid Treatment Impairs Bone Regenerative Capacity of Adipose Tissue-Derived Mesenchymal Stem Cells.

Glucocorticoids are steroid hormones used as anti-inflammatory treatments. However, this strong immunomodulation causes undesirable side effects that impair bones, such as osteoporosis. Glucocorticoid therapy is a major risk factor for developing steroid-induced osteonecrosis of the femur head (ONFH). Since ONFH is incurable, therapy with mesenchymal stem cells (MSCs) that can differentiate into osteoblasts are a first-line choice. Bone marrow-derived MSCs (BM-MSCs) are often used as a source of stem cell therapy for ONFH, but their proliferative activity is impaired after steroid treatment. Adipose tissue-derived MSCs (AT-MSCs) may be an attractive alternative source; however, it is unknown whether AT-MSCs from steroid-induced ONFH (sAT-MSCs) have the same differentiation ability as BM-MSCs or normal AT-MSCs (nAT-MSCs). In this study, we demonstrate that nAT-MSCs chronically exposed to glucocorticoids show lower alkaline phosphatase activity leading to reduced osteogenic differentiation ability. This impaired osteogenesis is mediated by high expression of Dickkopf1 (Dkk-1) that inhibits wnt/ß-catenin signaling. Increased Dkk-1 also causes impaired osteogenesis along with reductions in bone regenerative capacity in sAT-MSCs. Of note, plasma Dkk-1 levels are elevated in steroid-induced ONFH patients. Collectively, our findings suggest that glucocorticoid-induced expression of Dkk-1 could be a key factor in modulating the differentiation ability of MSCs used for ONFH and other stem cell therapies.

SDF-1 improves wound healing ability of glucocorticoid-treated adipose tissue-derived mesenchymal stem cells.

Glucocorticoids cause the delayed wound healing by suppressing inflammation that is required for wound healing process. Adipose tissue-derived mesenchymal stem cells (AT-MSCs) play an important role for wound healing by their cytokine productions including stromal derived factor 1 (SDF-1). However, it has not been clear how glucocorticoids affect the wound healing ability of AT-MSCs. In this study, we found that glucocorticoid downregulated SDF-1 expression in AT-MSCs. In addition, glucocorticoid-treated AT-MSCs induced less migration of inflammatory cells and impaired wound healing capacity compared with glucocorticoid-untreated AT-MSCs. Of note, prostaglandin E2 (PGE2) synthesis-related gene expression was downregulated by glucocorticoid and PGE2 treatment rescued not only SDF-1 expression in the presence of glucocorticoid but also their wound healing capacity in vivo. Furthermore, we found SDF-1-overexpressed AT-MSCs restored wound healing capacity even after treatment of glucocorticoid. Consistent with the results obtained from glucocorticoid-treated AT-MSCs, we found that AT-MSCs isolated from steroidal osteonecrosis donors (sAT-MSCs) who received chronic glucocorticoid therapy showed less SDF-1 expression and impaired wound healing capacity compared with traumatic osteonecrosis donor-derived AT-MSCs (nAT-MSCs). Moreover, the SDF-1 level was also reduced in plasma derived from steroidal osteonecrosis donors compared with traumatic osteonecrosis donors. These results provide the evidence that concomitant application of AT-MSCs with glucocorticoid shows impaired biological modulatory effects that induce impaired wound healing.

Serum-free isolation and culture system to enhance the proliferation and bone regeneration of adipose tissue-derived mesenchymal stem cells.

Cell therapy using human mesenchymal stem cells (MSCs) is an attractive approach for many refractory diseases. Adipose tissue-derived mesenchymal stem cells (AT-MSCs) are considered as a favorable tool due to its abundance in the body, easy proliferation, and high cytokine production potency. In order to avoid the risks associated with the use of fetal bovine serum (FBS) in culture that includes batch variations and contamination with pathogens, development of serum-free culture system has been initiated. We have formulated a completely serum-free culture medium (SFM) that could be used not only for the expansion of AT-MSCs but also for initial isolation. We demonstrate that the AT-MSCs isolated and cultured in serum-free medium (AT-MSCs/SFM) possess high proliferation capacity and differentiation potency to osteoblast, adipocyte, and chondrocyte lineages in vitro. In in vivo bone fraction model analysis, AT-MSCs/SFM showed higher bone repair potency and quality of the regenerated bone than the cells cultured in serum-containing medium (AT-MSCs/SCM). This was attributed to the (i) presence of translated cells in the bone, as evidenced by in vivo imaging of the illuminated translated cells and (ii) high level of expression and induction capacity of AT-MSCs/SFM for cytokine BMP2, CCL2, and CCL5. Taken together, we report a new serum-free culture system for AT-MSCs that is suitable for cell therapy.

Percutaneous coronary intervention is a useful bridge treatment for acute myocardial infarction due to acute type A aortic dissection.

We report a 71-year-old woman with inferior acute myocardial infarction (AMI) due to type A acute aortic dissection. Emergency enhanced computed tomography (CT) did not show obvious aortic dissection. During emergency percutaneous coronary intervention (PCI), intravascular ultrasonography revealed type A aortic dissection. Hemodynamic stability was restored after PCI. 1 month later, CT revealed a sinus of Valsalva aneurysm, which was treated surgically. This case suggests that PCI could be a good initial treatment option for unstable patients with AMI due to type A aortic dissection. This is the first reported case of sinus of Valsalva aneurysm subsequent to aortic dissection.

Termination of recurrent ventricular tachycardia by continuous positive airway pressure ventilation.

We report a case of hypertrophic cardiomyopathy with recurrent ventricular tachycardia that resolved after initiating continuous positive airway pressure therapy.

Association of hypoadiponectinemia in men with early onset of coronary heart disease and multiple coronary artery stenoses.

Adiponectin influences insulin sensitivity and lipid oxidation. Because low plasma adiponectin concentrations are suspected to promote atherosclerosis, we retrospectively assessed relationships of plasma adiponectin concentration to characteristics of coronary heart disease (CHD). Japanese men undergoing coronary angiography for CHD (n = 139) were grouped according to serum adiponectin concentration by enzyme-linked immunosorbent assay (low, <4.0; medium, 4.0-8; high, >8.0 microg/mL). Numbers of coronary arteries with at least 50% stenosis were determined. Serum adiponectin concentration correlated positively with age at onset of CHD (r = 0.285, P = .003). Age at CHD onset in the low-adiponectin group was younger than in the medium or high groups. Adiponectin was protective against CHD onset at ages younger than 58 years (relative risk, 0.778; P = .0047). Significantly more arteries were affected in low-adiponectin patients than in the medium or high group (each P < .01). Adiponectin concentration correlated positively with high-density lipoprotein cholesterol concentration and negatively with triglyceride concentration. Only in diabetic patients did serum adiponectin concentration correlate negatively with body mass index. Low plasma adiponectin concentrations were associated with early CHD onset and multiple atherosclerotic lesions in coronary arteries. Thus, adiponectin concentrations may influence risk of CHD and might serve as one of the screening tests facilitating early intervention.