Selenium Discrepancies in Fetal Bovine Serum: Impact on Cellular Selenoprotein Expression.

Selenium is an essential trace element in our diet, crucial for the composition of human selenoproteins, which include 25 genes such as glutathione peroxidases and thioredoxin reductases. The regulation of the selenoproteome primarily hinges on the bioavailability of selenium, either from dietary sources or cell culture media. This selenium-dependent control follows a specific hierarchy, with "housekeeping" selenoproteins maintaining constant expression while "stress-regulated" counterparts respond to selenium level fluctuations. This study investigates the variability in fetal bovine serum (FBS) selenium concentrations among commercial batches and its effects on the expression of specific stress-related cellular selenoproteins. Despite the limitations of our study, which exclusively used HEK293 cells and focused on a subset of selenoproteins, our findings highlight the substantial impact of serum selenium levels on selenoprotein expression, particularly for GPX1 and GPX4. The luciferase reporter assay emerged as a sensitive and precise method for evaluating selenium levels in cell culture environments. While not exhaustive, this analysis provides valuable insights into selenium-mediated selenoprotein regulation, emphasizing the importance of serum composition in cellular responses and offering guidance for researchers in the selenoprotein field.

Release of metal elements from the Essure implant: A prospective cohort study.

OBJECTIVE(S): The causal mechanistic relationships between Essure® and adverse effects are unclear, but corrosion in the in-vivo environment with release of metal ions may be suspected. Here we evaluated the concentrations of nickel (Ni), chromium (Cr) and tin (Sn) in the peritoneal fluid (PF) and in the fallopian tube (FT) during laparoscopic Essure® removal compared to a control group. STUDY DESIGN: Ni, Cr and Sn concentrations were determined in the PF and FT from two groups(group A: symptomatic patients with Essure®) vs group B (control group without Essure®) by Inductively Coupled Plasma Mass Spectrometry analysis. Correlation between metal elements concentrations and reported pre-operative symptoms was also investigated. RESULTS: There were 131 patients in group A vs 92 control patients in group B. The concentrations of Cr and Ni in PF between both groups were significantly different (p < 0.0001) while there was no statistical difference for Sn (p = 0.58). There was also a significantly higher concentration in the FT for the 3 metal elements in group A than in group B (p < 0.0001). There were differential dynamics of the levels of metal elements based on the length of time between the placement and removal of Essure®. CONCLUSIONS: There was a chronic exposure to metal elements in symptomatic patients with Essure® raising the question of the relationship between adverse effects and these potential toxic metals.

Potential release of toxic metal elements from Essure® device in symptomatic patients: First results of the French Ablimco cohort.

OBJECTIVE: Many patients with Essure® devices request the removal of these implants due to persistent adverse effects. The pathophysiology remains unknown, but a corrosion of the implants in the in-vivo environment leading to metal ion release may be suspected. The implants consist of polyester fibers, nickel-titanium alloy and other metals including chromium. The purpose of this study is to deliver the first results on the concentrations of nickel and chromium (two potential toxic metal elements) in peritoneal fluid and in the fallopian tube tissue during laparoscopic removal of Essure®. STUDY DESIGN: In this prospective observational study conducted in a French academic research hospital (University hospital of Lyon), nickel and chromium concentrations were determined in the fallopian tube tissue and peritoneal liquid from symptomatic patients with Essure® by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis in a PerkinElmer NexION 350. RESULTS: Significant metal element concentrations were showed in the peritoneal fluid. There was also a differential concentration in the fallopian tube tissue with higher concentration close to the implant then lower at a distance from this implant. There was a correlation between the concentrations of the two metals. CONCLUSION: The presence of nickel and chromium in the fallopian tube tissue and the peritoneal fluid raises the question of a possible relationship between the symptoms attributed to Essure® implants and the dissemination of potential toxic metals due to galvanic corrosion of the devices.