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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.

Distribution of selected metals in pregnant and foetal rat tissues under exposure to cigarette smoke

80%

Czekaj P. , Palasz A. , Donica E. , Florek E.

nr 2

Accumulation of cadmium, lead and mercury in human placenta as a consequence of maternal cigarette smoking

80%

Czekaj P. , Palasz A. , Donica E. , Karczewska W.

nr 2

Ischemia-reperfusion of the liver impairs the inducibility of microsomal cytochrome P450 system by phenobarbital in rats

70%

Wiaderkiewicz R. , Wiaderkiewicz A. , Czekaj P. , Lebda-Wyborny T. , Kaszuba M.

nr 2

Effect of pyrantel and dimethoate administration on rat liver cytochrome P450 system

61%

Wiaderkiewicz R. , Zasadowski A. , Czekaj P. , Wiaderkiewicz A. , Czajkowska B. , Barski D. , Palasz A.

nr 2

Circadian changes in ATP-ase Mg activity and in Mg and Ca content of rat liver in relation to age and season

61%

Wielgus-Serafinska E. , Pawlicki K. , Kaminski M. , Nowaczyk-Dura G. , Plewka A. , Czekaj P.

nr 4

This experiment was carried out on male Wistar rats aged 6, 12, and 24 months in two seasons, autumn and winter. In all age groups, the activity of Mg-dependent ATP-ase (Mg2+ -ATPase) showed rhythmic oscillations with a 12-hour period. A similar time course was observed for 12-hour variations in Mg and Ca concentrations. In both seasons the maxima of ATP-ase Mg activity paralleled the maxima of Mg and Ca concentrations. When two maxima were observed, one of them always occurred in the light phase and the other in the dark phase of the 24-hour LDcycle.

The comparison of multipotential for differentiation of progenitor mesenchymal-like stem cells obtained from livers of young and old rats

41%

Tarnowski M. , Koryciak-Komarska H. , Czekaj P. , Sebesta R. , Czekaj T. M. , Urbanek K. , Likus W. , Malinowska-Kolodziej I. , Plewka D. , Nowaczyk-Dura G. , Wiaderkiewicz R. , Sieron A. L.

tom 45

nr 3