An improvement in the small-volume technique for determining thorium-234 in seawater

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 100 (2006): 282-288, doi:10.1016/j.marchem.2005.10.016.The recently developed 2‐5 L small‐volume MnO2 coprecipitation method for determining 234Th in seawater has provided a new way to substantially increase, both temporally and spatially, the sampling resolution of 234Th and 234Th‐based particulate organic carbon export estimates in the upper ocean. In this study, we further optimize the technique by reducing reagent quantities and the use of an additional water bath heating step. This optimization allows the filtration of the MnO2 precipitate onto a 25‐mm diameter, 1.0 μm pore size QMA filter to be completed within < 30 minutes for unfiltered waters from the South China Sea. In addition, we have modified the MnO2 purification procedure to allow for alpha spetrometric measurements of 234Th recoveries. Results from recovery experiments suggest that reagent amounts can be reduced to 0.0375 mg KMnO4 and 0.1 mg MnCl2∙4H2O per liter of sample, while still maintaining high 234Th recovery. This study further confirms that the addition of a yield monitor is necessary for the application of this small‐volume method.Support for this work came from the Natural Science Foundation of China through grants #40206011, #49825162, and #90211020. This study was also supported by the China Ministry of Education through a program for Changjiang Scholars and Innovative Research Teams in Universities (PRSIRT)

Extracellular vesicles from prostate tumors reshape the pre-metastatic bone environment in an mTOR/RAB1A-dependent manner

BackgroundBone is the most common metastatic site in prostate cancer (PCa) patients and serves as a key contributing factor to the poor prognosis observed in advanced-stage patients. Mammalian target of rapamycin (mTOR) inhibition has limited clinical efficacy, potentially due to pathway complexity. Prior to the colonization by tumor cells, primary PCa cells actively remodel the bone microenvironment through the secretion of mediators including extracellular vesicles (EVs). The objective of this research is to investigate the regulatory mechanisms of EV biogenesis and the effects of EVs on the bone pre-metastatic niche (PMN), offering a novel therapeutic strategy against bone metastasis.MethodsPCa cell lines were employed to detect mTOR and Ras-related protein Rab-1A (RAB1A) protein expression levels via Western blotting (WB). Functional assays (invasion and proliferation) were used to validate the impact of RAB1A expression on biological behavior. The biological characteristics of EVs were characterized using WB, nanoparticle tracking analysis, and transmission electron microscopy. Bone marrow cell subpopulation alterations were analyzed based on the GSE143791 single-cell dataset. Cells and animal models were treated with EVs to assess their effects on the bone marrow microenvironment, survival time, and bone metastatic burden. Finally, peripheral blood routine parameters were compared in patients with or without bone metastasis.ResultsUtilizing PCa cell lines, we demonstrated that mTOR activation inhibits the ubiquitination activity of the oncogenic factor RAB1A, thereby stabilizing its expression. The EVs derived from tumor promoted bone immunosuppression via B-cell dysfunction and myeloid cell expansion, highlighting their role in PMN formation. In RAB1A-overexpressing PCa animal models, GW4869-mediated inhibition of EV secretion prolonged mice survival, ameliorated bone marrow abnormalities, enhanced B-cell activation capacity, and reduced regulatory B-cell proportions.ConclusionsOur findings elucidated the detailed mechanism by which mTOR/RAB1A regulates EV secretion, providing new insight into cellular changes involved in PMN formation and a theoretical basis for the inhibition of the PMN in the development of targeted therapies for PCa. RAB1A represents a therapeutic target to reverse tEV-mediated immunosuppression, while peripheral B-cell dynamics provide diagnostic biomarkers for early metastasis detection

Comparison of staged-stent and stent-assisted coiling technique for ruptured saccular wide-necked intracranial aneurysms: Safety and efficacy based on a propensity score-matched cohort study

BackgroundApplication of stent-assisted coiling and FD in acute phase of ruptured wide-necked aneurysms is relatively contraindicated due to the potential risk of ischemic and hemorrhagic complications. Scheduled stenting after initial coiling has emerged as an alternative paradigm for ruptured wide-necked aneurysms. The objective of this study is to evaluate the safety and efficacy of a strategy of staged stent-assisted coiling in acutely ruptured saccular wide-necked intracranial aneurysms compared with conventional early stent-assisted coiling strategy via propensity score matching in a high-volume center.MethodsA retrospective review of patients with acutely ruptured saccular wide-necked intracranial aneurysms who underwent staged stent-assisted coiling or conventional stent-assisted coiling from November 2014 to November 2019 was performed. Perioperative procedure-related complications and clinical and angiographic follow-up outcomes were compared.ResultsA total of 69 patients with staged stent-assisted coiling and 138 patients with conventional stent-assisted coiling were enrolled after 1:2 propensity score matching. The median interval time between previous coiling and later stenting was 4.0 weeks (range 3.5–7.5 weeks). No rebleeding occurred during the intervals. The rate of immediate complete occlusion was lower with initial coiling before scheduled stenting than with conventional stent-assisted coiling (21.7 vs. 60.9%), whereas comparable results were observed at follow-up (82.5 vs. 72.9%; p = 0.357). The clinical follow-up outcomes, overall procedure-related complications and procedure-related mortality between the two groups demonstrated no significant differences (P = 0.232, P = 0.089, P = 0.537, respectively). Multivariate analysis showed that modified Fisher grades (OR = 2.120, P = 0.041) were independent predictors for overall procedure-related complications and no significant predictors for hemorrhagic and ischemic complications.ConclusionsStaged stent-assisted coiling is a safe and effective treatment strategy for acutely ruptured saccular wide-necked intracranial aneurysms, with comparable complete occlusion rates, recurrence rates at follow-up and overall procedure-related complication rates compared with conventional stent-assisted coiling strategy. Staged stent-assisted coiling could be an alternative treatment option for selected ruptured intracranial aneurysms in the future

A high-resolution study of particle export in the southern South China Sea based on Th-234 : U-238 disequilibrium

During a spring intermonsoon cruise in 2004, depth profiles of total and particulate Th-234 in the upper 100 m were collected at 36 stations in the southern South China Sea (SCS), covering a surface area of similar to 1.0 x 10(6) km(2). Thorium-234 was sampled by using a modified small-volume MnO2 co-precipitation technique, which allows mapping the Th-234 distribution with a high spatial resolution. A stratified structure of Th-234/U-238 disequilibria was generally observed in the upper 100 m water column, suggesting that the euphotic zone of the southern SCS in this season can be separated into two layers: an upper layer with low export production rates and a lower layer with high export production rates. At the same time, we observed extensive zones of Th-234 excess within the euphotic layer, which is possibly due to intense remineralization of particulate matter. Particulate organic carbon (POC) export was estimated from a three-dimensional steady state model of Th-234 fluxes combined with measurements of the POC/Th-234 ratio on suspended particles. The POC export for this region varied from a low of -10.7 +/- 1.5 mmolC m(-2) d(-1) to a high of 12.6 +/- 1.1 mmolC m(-2) d(-1), with an average of 3.8 +/- 4.0 mmolC m(-2) d(-1). A negative flux of POC export is interpreted as the result of lateral input of particulate matter from nearby waters. Regional patterns in POC export show enhanced fluxes along the western and southern boundaries of the study region, and a "tongue'' of low export extending northwestward from similar to 7 degrees N 116 degrees E to similar to 10 degrees N 111 degrees E. This geographic distribution is consistent with the overall surface circulation pattern of the southern SCS in this season