Seasonal Formation of Low-Sorbing Methylthiolated Arsenates Induces Arsenic Mobilization in a Minerotrophic Peatland.

Peatlands are known sinks for arsenic (As). In the present study, seasonal As mobilization was observed in an acidic, minerotrophic peatland (called Lehstenbach) in late summer, accompanied by a peak in dissolved sulfide (S(-II)). Arsenic speciation revealed the lowest seasonal porewater concentrations of arsenite and arsenate, likely due to As(III)-S-bridging to natural organic matter. Arsenic mobilization was driven by the formation of arsenite-S(-II) colloids and formation of methylthiolated arsenates (up to 59% of the sum of As species) and to a minor extent also of inorganic thioarsenates (6%-30%) and oxymethylated arsenates (5%-24%). Sorption experiments using a purified model peat, the Lehstenbach peat, natural (to mimic winter conditions) and reacted with S(-II) (to mimic late summer conditions) at acidic and neutral pH confirmed low sorption of methylthiolated arsenates. At acidic pH and in the presence of S(-II), oxymethylated arsenates were completely thiolated. This methylthiolation decreased As sorption up to 10 and 20 times compared with oxymethylated arsenates and arsenite, respectively. At neutral pH, thiolation of monomethylated arsenates was incomplete, and As could be partially retained as oxymethylated arsenates. Dimethylated arsenate was still fully thiolated and highly mobile. Misidentification of methylthiolated arsenates as oxymethylated arsenates might explain previous contradictory reports of methylation decreasing or increasing As mobility.

Autologous bone marrow mononuclear cell infusion for liver cirrhosis after the Kasai operation in children with biliary atresia.

AIM: To evaluate the safety and early outcomes of autologous bone marrow mononuclear cell (BMMNC) infusion for liver cirrhosis due to biliary atresia (BA) after Kasai operation. METHODS: An open-label clinical trial was performed from January 2017 to December 2019. Nineteen children with liver cirrhosis due to BA after Kasai operation were included. Bone marrow was harvested through anterior iliac crest puncture under general anesthesia. Mononuclear cells (MNCs) were isolated by Ficoll gradient centrifugation and then infused into the hepatic artery. The same procedure was repeated 6 months later. Serum bilirubin, albumin, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and prothrombin time were monitored at baseline, 3 months, 6 months, and 12 months after the first transplantation. Esophagoscopies and liver biopsies were performed in patients whose parents provided consent. Mixed-effect analysis was used to evaluate the changes in Pediatric End-Stage Liver Disease (PELD) scores. RESULTS: The average MNC and CD34+ cell counts per kg body weight were 50.1 ± 58.5 × 106/kg and 3.5 ± 2.8 × 106 for the first transplantation and 57.1 ± 42.0 × 106/kg and 3.7 ± 2.7 × 106 for the second transplantation. No severe adverse events associated with the cell therapy were observed in the patients. One patient died 5 months after the first infusion at a provincial hospital due to the rupture of esophageal varices, while 18 patients survived. Liver function was maintained or improved after infusion, as assessed by biochemical tests. The severity of the disease reduced markedly, with a significant reduction in PELD scores. CONCLUSION: Autologous BMMNC administration for liver cirrhosis due to BA is safe and may maintain or improve liver function. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03468699. Name of the registry: Vinmec Research Institute of Stem Cell and Gene Technology. https://clinicaltrials.gov/ct2/show/NCT03468699?cond=biliary+atresia&cntry=VN&draw=2&rank=2 . Registered on March 16, 2018. The trial results will also be published according to the CONSORT statement at conferences and reported in peer-reviewed journals.