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Toxicological and cytophysiological aspects of lanthanides action

100%

Palasz A. , Czekaj P.

nr 4

Lanthanides, also called rare-earth elements, are an interesting group of 15 chemically active, mainly trivalent, f-electronic, silvery-white metals. In fact, lanthanides are not as rare as the name implies, except for promethium, a radioactive artificial element not found in nature. The mean concentrations of lanthanides in the earth's crust are comparable to those of life-important elements like iodine, cobalt and selenium. Many lanthanide compounds show particular magnetic, catalytic and optic properties, and that is why their technical applications are so extensive. Numerous industrial sources enable lanthanides to penetrate into the human body and therefore detailed toxicological studies of these metals are necessary. In the liver, gadolinium selectively inhibits secretion by Kupffer cells and it decreases cytochrome P450 activity in hepatocytes, thereby protecting liver cells against toxic products of xenobiotic biotransformation. Praseodymium ion (Pr3+) produces the same protective effect in liver tissue cultures. Cytophysiological effects of lanthanides appear to result from the similarity of their cationic radii to the size of Ca2+ ions. Trivalent lanthanide ions, especially La3+ and Gd3+, block different calcium channels in human and animal cells. Lanthanides can affect numerous enzymes: Dy3+ and La3+ block Ca2+-ATPase and Mg2+-ATPase, while Eu3+ and Tb3+ inhibit calcineurin. In neurons, lanthanide ions regulate the transport and release of synaptic transmitters and block some membrane receptors, e.g. GABA and glutamate receptors. It is likely that lanthanides significantly and uniquely affect biochemical pathways, thus altering physiological processes in the tissues of humans and animals.

Zastosowanie naturalnych sorbentów nieorganicznych do adsorpcji jonów lantanowców

84%

Gładysz-Płaska A. , Majdan M.

tom T. 85, nr 3

182-188

Przedstawiono przegląd literaturowy badań sorpcji jonów lantanowców na różnego typu sorbentach nieorganicznych pochodzenia naturalnego, takich jak tlenki żelaza, manganu, glinu i krzemu oraz minerały ilaste. Szczególną uwagę zwrócono na współczynniki podziału jonów Ln(III) między fazę wodną a fazę stałą.

A review with 43 refs. covering adsorption of Ln(III) ions on Fe, Al, Mn or Si oxyhydroxides or on Al, Mg and Fe aluminosilicates, and the distribution coeffs. of Ln(III) ions between the aq. and the solid phase.

Content of 27 selected elements in the potentially mobile fraction of tsunami sediments

51%

Kozak L. , Machat J. , Niedzielski P.

Polish Journal of Environmental Studies

2009

tom 18

nr 1

131-136

Our paper reports results of a study on the bioavailability of selected elements from sediments deposited by the tsunami event of 26 December 2004 in south Thailand. In January 2005, 15 samples of the sediments deposited by the tsunami were collected at four different localities. The reference sample was collected in an area not affected by the tsunami. In the acid leachable sediments fraction (the bioavailable fraction) the contents of 27 selected elements (Be, Ga, Bi, Rb, Cs, Sn, Mn, Re, Co, Rh, Ru, Mo, V, Nb, Ta, Zr, Sc, Th, Pt, La, Ce, Nd, Eu, Gd, Tb, Ho, Lu) were determined using ICP-MS. The measurements were repeated after one year to establish a potential effect of the rainy season on the content of these elements in this fraction.