Hi Olga,

I have never heard something about the role that Cerium might play in human cells (most probably none, at least with respect to current knowledge), but you may wish to look at this recent publication from microbiology, claiming the importance of Cerium and other lanthanoids for Archaea that live on methane.

"Rare earth metals are essential for methanotrophic life in volcanic mudpots"

Pol, A (Pol, Arjan)[ 1 ] ; Barends, TRM (Barends, Thomas R. M.)[ 3 ] ; Dietl, A (Dietl, Andreas)[ 3 ] ; Khadem, AF (Khadem, Ahmad F.)[ 1 ] ; Eygensteyn, J (Eygensteyn, Jelle)[ 2 ] ; Jetten, MSM (Jetten, Mike S. M.)[ 1 ] ; Op den Camp, HJM (Op den Camp, Huub J. M.)[ 1 ]

ENVIRONMENTAL MICROBIOLOGY Volume:16 (2014)  Issue:1 Pages:255-264

Special Issue:SI

DOI:10.1111/1462-2920.12249

Abstract

Growth of Methylacidiphilum fumariolicumSolV, an extremely acidophilic methanotrophic microbe isolated from an Italian volcanic mudpot, is shown to be strictly dependent on the presence of lanthanides, a group of rare earth elements (REEs) such as lanthanum (Ln), cerium (Ce), praseodymium (Pr) and neodymium (Nd). After fractionation of the bacterial cells and crystallization of the methanol dehydrogenase (MDH), it was shown that lanthanides were essential as cofactor in a homodimeric MDH comparable with one of the MDHs of Methylobacterium extorquensAM1. We hypothesize that the lanthanides provide superior catalytic properties to pyrroloquinoline quinone (PQQ)-dependent MDH, which is a key enzyme for both methanotrophs and methylotrophs. Thus far, all isolated MxaF-type MDHs contain calcium as a catalytic cofactor. The gene encoding the MDH of strain SolV was identified to be a xoxF-ortholog, phylogenetically closely related to mxaF. Analysis of the protein structure and alignment of amino acids showed potential REE-binding motifs in XoxF enzymes of many methylotrophs, suggesting that these may also be lanthanide-dependent MDHs. Our findings will have major environmental implications as metagenome studies showed (lanthanide-containing) XoxF-type MDH is much more prominent in nature than MxaF-type enzymes.

Hello Dear Johannes!

Thanks for the great information. Yours Faithfully Olga

Dear Vladimir! Thank you very much for such a valuable and interesting information. You are absolutely right that many works were forgotten. That is a pity.

Sincerely Olga

For Baryum see:

Acute respiratory distress syndrome following inhalation of barium sulfate

http://www.sciencedirect.com.www.sndl1.arn.dz/science/article/pii/S0761842505855767

Intoxication par sulfate de baryum?

http://www.sciencedirect.com.www.sndl1.arn.dz/science/article/pii/S0750765899800963

Acute barium intoxication

http://www.sciencedirect.com.www.sndl1.arn.dz/science/article/pii/S0750765805810019

For Cerium see:

Pilot in vivo investigation of cerium oxide nanoparticles as a novel anti-obesity pharmaceutical formulation

http://www.sciencedirect.com.www.sndl1.arn.dz/science/article/pii/S1549963415001124

Thank you very much!

Thanks a lot! Best wishes!