Simple and rapid formic acid sample treatment for the isolation of HgSe nanoparticles from animal tissues

The present work explores for the first time the potential of formic acid on the extraction of tiemannite (HgSe) nanoparticles from seabird tissues, in particular giant petrels. Mercury (Hg) is considered one of the top ten chemicals of major public health concern. However, the fate and metabolic pathways of Hg in living organisms remain unknown. Methylmercury (MeHg), largely produced by microbial activity in the aquatic ecosystems is biomagnified in the trophic web. HgSe is considered the end-product of MeHg demethylation in biota and an increasing number of studies focuses on the characterization of this solid compound to understand its biomineralization. In this study, a conventional enzymatic treatment is compared with a simpler and environmentally friendly extraction by using formic acid (5 mL of = 50 % formic acid) as exclusive reagent. The analyses by spICP-MS of the resulting extracts from a variety of seabird biological tissues (liver, kidneys, brain, muscle) reveal comparable results by both extraction approaches in terms of nanoparticles stability and extraction efficiency. Therefore, the results included in this work demonstrate the good performance of employing organic acid as simple, cost effective and green procedure to extract HgSe nanoparticles from animal tissues. Moreover, an alternative consisting of a classical enzymatic procedure but with ultrasonic assistance reducing the extraction time from 12 h to 2 min is also described for the first time. The sample processing methodologies developed, combined with spICP-MS, have emerged as powerful tools for the rapid screening and quantification of HgSe nanoparticles in animal tissues. Finally, this combination allowed us to identify the possible occurrence of Cd particles and As particles associated with HgSe NPs in seabirds.

The tolerance and efficacy of a postponed retreatment with infliximab in Crohn's disease primary responders

BACKGROUND

In Crohn's disease (CD) patients naïve to immunomodulators primary responding to infliximab (IFX) induction, maintenance with scheduled IFX or with immunomodulators is possible. The benefit of additional IFX infusions after failure of maintenance with immunomodulators is not known.

AIM

To assess the efficacy and factors associated with efficacy of postponed IFX retreatment.

METHODS

All CD primary responders to an IFX induction regimen in maintenance with immunomodulators were retrospectively included when they received at least one additional IFX infusion after week 14. Efficacy was defined as clinical response at week 4 and absence of intolerance leading to discontinuation.

RESULTS

Sixty-one patients were retreated with IFX with a 38-week median time from induction. Efficacy was achieved in 80% patients. Twelve patients had no clinical benefit: seven acute hypersensitivity reactions and five loss of response. By multivariate analysis, the only factor associated with no efficacy was a median time >50 weeks from induction to retreatment (odds ratio = 7.38; 95%CI: 1.38-39.59; P = 0.02).

CONCLUSION

Postponed retreatment with IFX in CD primary responders should be administered within 50 weeks after induction, for better efficacy and tolerance.