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1

Interakcje receptorow hormonu tarczycy i pochodnych witamin A i D z DNA.

100%
Czekaj P.
Postępy Biologii Komórki
|
1996
|
tom 23
|
nr 2
261-278
2

Phenobarbital-induced expression of cytochrome P450 genes

100%
Czekaj P.
Acta Biochimica Polonica
|
2000
|
tom 47
|
nr 4
In contrast to the well-known Ah receptor-mediated regulation of the CYP1A1 gene by polycyclic aromatic hydrocarbons, the molecular mechanism by which phenobarbital (PB) and PB-like inducers affect transcription of CYP genes remains unknown; no receptor for these chemicals has been found to date. However, in the last 5 years PB-responsive sequences have been identified in the 5' flanking regions of several P450 genes. The phenobarbital-responsive enhancer unit (PBRU) of CYP2B gene family members contain two potential nuclear receptor binding sites (NR1 and NR2) that flank a nuclear factor 1 (NF-1) binding motif. The nuclear factors that regulate PBRU activity have not yet been characterized. It seems that PB may activate multiple nuclear orphan receptors to induce various CYP genes. CYP2B and CYP3A genes appear to be targets for the orphan receptors CAR and PXR, respectively. It is also possible that the pleiotropic effects of PB can, in part, be explained by the ability of the CAR-RXR heterodimer to bind to a variety of nuclear receptor binding motifs. The induction of cytochromes P450 may result in interactions between xenobiotics and in the interference of xenobiotic metabolism and endogenous signalling pathways.
3

Molecular and cellular mechanisms of chemically induced hepatocarcinogenesis

100%
Czekaj P.
Polish Journal of Environmental Studies
|
2004
|
tom 13
|
nr 5
Liver is the main organ of xenobiotic biotransformation. Since biotransformation may generate highly mutagenic active metabolites and reactive oxygen species, liver cells are both the producers and targets for these compounds. Xenobiotics can lead to liver tumour formation via genotoxic or non-genotoxic mechanisms. Non-genotoxic chemicals are often inducers of monooxygenase reactions depending on cytochrome P450 isoforms, active metabolites of which are potencial carcinogens. Moreover, non-genotoxic xenobiotics influence expression of genes responsible for cell proliferation and apoptosis. Increased proliferation may lead to an increased number of cells mutated as a result of genotoxic effects. In animal models of hepatocarcinogenesis at least three steps of tumour development are characterized: initiation, promotion and progression, but it is still unclear what the cellular origin of the liver cancer is. It is likely that either cancer cells originate from differentiated adult hepatocytes or from undifferentiated liver stem cells. Better knowledge about cell changes in neoplastic transformation during hepatocarcinogenesis and gaining control over this process may lead to determination of therapy alternative to cytostatic treatment.
4
Content available remote

Membrane estrogen receptors - is it an alternative way of estrogen action?

63%
Soltysik K., Czekaj P.
Journal of Physiology and Pharmacology
|
2013
|
tom 64
|
nr 2
5

Crime and the standard of living in Poland

63%
Jaworska M., Czekaj P.
Intercathedra
|
2017
|
tom 33
|
nr 1
The purpose of the paper is to conduct a statistical analysis that will examine the problem of crime against the standard of living. The paper attempts to determine the relationship between the level of crime in Poland, and the standard of life. A ranking of provinces, determining the level of crime and quality of life, was created. In order to sort the objects the method of multidimensional comparative analysis was used. By using this method, the hierarchy of provinces was created. The research enabled indicating groups of objects that are similar in the examined phenomena.
6

Toxicological and cytophysiological aspects of lanthanides action

63%
Palasz A., Czekaj P.
Acta Biochimica Polonica
|
2000
|
tom 47
|
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.
7

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

51%
Czekaj P., Palasz A., Donica E., Florek E.
Acta Poloniae Toxicologica
|
2002
|
tom 10
|
nr 2
8

Expression of cytochrome CYP2B1-2 in nonpregnant, pregnant and fetal rats exposed to tobacco smoke

51%
Czekaj P., Wiaderkiewicz A., Florek E., Wiaderkiewicz R.
Acta Biochimica Polonica
|
2000
|
tom 47
|
nr 4
Four-month-old female Wistar rats were exposed for 20 days to tobacco smoke obtained from non-filter cigarettes. During the exposure, concentration of tobacco smoke was monitored indirectly by measuring the CO level (1500 mg/m3 air). The efficacy of exposure was assessed by measuring urine nicotine and cotinine levels. Cigarette smoke did not change total cytochrome P450 and b5 protein levels in any of the organs studied, and most of these organs did not show any changes in the activity of reductases associated with these cytochromes. Following exposure to tobacco smoke, fetal rat liver expressed CYP2B1/2 protein; in newborns (day 1) both liver and lung showed CYP2B1/2 protein expression and very low pentoxyresorufin O-dealkylase activity. Western blot analysis of adult liver, lung, heart, but not of brain microsomes, showed that tobacco smoke induced CYP2B1/2 in both nonpregnant and pregnant rats, though its expression was lower in the livers and hearts of pregnant females. In the rat and human placenta, neither rat CYP2B1/2 nor human CYP2B6 showed basal or tobacco smoke-induced expression at the protein level. This study shows clearly that the expression of CYP2B1/2, which metabolizes nicotine and some drugs and activates carcinogens, is controlled in rats by age-, pregnancy-, and tissue-specific regulatory mechanisms.
9

Immunodetection of cytochrome P450 isoforms in fetus and adult female Wistar rats

51%
Czekaj P., Wiaderkiewicz A., Wiaderkiewicz R.
Acta Poloniae Toxicologica
|
2000
|
tom 08
|
nr 1
10

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

51%
Czekaj P., Palasz A., Donica E., Karczewska W.
Acta Poloniae Toxicologica
|
2002
|
tom 10
|
nr 2
11

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

45%
Wiaderkiewicz R., Wiaderkiewicz A., Czekaj P., Lebda-Wyborny T., Kaszuba M.
Acta Poloniae Toxicologica
|
2002
|
tom 10
|
nr 2
12

Cytochrome P450 mRNA expressions along with in vitro differentiation of hepatocyte precursor cells from fetal, young and old rats

39%
Czekaj P., Bryzek A., Czekaj T. M., Koryciak-Komarska H., Wiaderkiewicz A., Plewka D., Sieron A. L.
Folia Histochemica et Cytobiologica
|
2010
|
tom 48
|
nr 1
46-57
13

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

39%
Wiaderkiewicz R., Zasadowski A., Czekaj P., Wiaderkiewicz A., Czajkowska B., Barski D., Palasz A.
Bulletin of the Veterinary Institute in Puławy
|
2006
|
tom 50
|
nr 2
14

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

39%
Wielgus-Serafinska E., Pawlicki K., Kaminski M., Nowaczyk-Dura G., Plewka A., Czekaj P.
Polish Journal of Environmental Studies
|
1996
|
tom 05
|
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.
15

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

27%
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.
Folia Histochemica et Cytobiologica
|
2007
|
tom 45
|
nr 3
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