Wyniki wyszukiwania - Biblioteka Nauki

1

Side-chain modified vitamin D analogs require activation of both PI 3-K and erk1,2 signal transduction pathways to induce differentiation of human promyelocytic leukemia cells.

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Marcinkowska E. , Kutner A.

Acta Biochimica Polonica

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2002

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tom 49

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nr 2

393-406

EN

Synthetic analogs of vitamin D for potential use in differentiation therapy should selectively regulate genes necessary for differentiation without inducing any perturbations in calcium homeostasis. PRI-1906, an analog of vitamin D2, and PRI-2191, an analog of vitamin D3 bind nuclear vitamin D receptor (nVDR) with substantially lower affinity than 1,25-dihydroxyvitamin D3 (1,25-D3), but have higher differentiation-inducing activity as estimated in HL-60 leukemia cell model. To examine how their increased differentiation-inducing activity is regulated we tested the hypothesis that membrane-mediated events, unrelated to nVDR, take part in the differentiation in response to PRI-1906 and PRI-2191. The induction of leukemia cell differentiation in response to the analogs of vitamin D was inhibited by LY294002 (phosphatidylinositol 3-kinase inhibitor), PD98059 (inhibitor of MEK1,2, an upstream regulator of extracellular-signal regulated kinase) and rapamycin (p70S6K inhibitor) pointing out that activation of signal transduction pathways unrelated to nVDR is necessary for differentiation. On the other hand, inhibition of cytosolic phospholipase A2 accelerated the differentiation of HL-60 cells induced by either 1,25-D3 or by the vitamin D analogs suggesting possible existence of a feedback loop between extracellular-signal regulated kinases and phospholipase A2.

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Mechanical Properties of Lining Leathers Finished with the Addition of Oregano Essential Oil

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Bielak E. , Marcinkowska E.

Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie

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2017

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nr 7(967)

19-31

EN

The hygienic properties of lining leathers can be improved significantly by introducing oregano essential oil into leathers. This is because adding antiseptic oil makes leathers more resistant to microorganisms that are potentially harmful to humans and cause damage to animal leathers. The paper presents the results of tests to check selected mechanical properties – tensile strength, elongation and tear load – of leathers fatliquored with oregano essential oil at a concentration of 3% w/w and without this treatment. The tests were carried out on the Instron 5544 testing machine. The leathers enriched with oil met the standard requirements set for lining leathers for of the parameters: tensile strength and elongation. Statistical analysis using the chi-squared, Hartley and Fisher-Snedecor tests at an assumed significance level of α = 0.05 revealed that leather enriched with oregano essential oil has a significantly higher tensile strength than leather fatliquored without this oil, while both leather samples showed no significant difference in elongation and tear load. Thus, it can be concluded that adding 3% w/w of oil will have not have an adverse effect on basic mechanical properties of leathers.

PL

Higieniczność skór podszewkowych można znacząco poprawić dzięki wprowadzeniu do skóry olejku lebiodkowego, ponieważ dodatek olejku o działaniu antyseptycznym pozwala na nadanie skórze oporności wobec mikroorganizmów potencjalnie szkodliwych dla człowieka oraz powodujących destrukcję skór zwierzęcych. W artykule przedstawiono wyniki badań wybranych właściwości mechanicznych skór natłuszczonych z dodatkiem oraz bez dodatku olejku lebiodkowego w stężeniu 3% na masę skóry, tj. wytrzymałości na rozciąganie, wydłużenia i siły rozdzierającej, które wykonano na maszynie wytrzymałościowej Instron 5544. Skóry uszlachetnione olejkiem spełniały wymagania podane w normie wyrobu stawiane skórom podszewkowym w zakresie wytrzymałości na rozciąganie oraz wydłużenia. Analiza statystyczna z wykorzystaniem testów chi-kwadrat, Hartleya oraz Fishera-Snedecora przy przyjętym poziomie istotności α = 0,05 wykazała, że w przypadku badanych próbek wytrzymałość na rozciąganie skóry z dodatkiem olejku lebiodkowego była istotnie wyższa od wartości tego parametru w skórze natłuszczonej bez dodatku olejku, zaś wydłużenie oraz siła rozdzierająca skóry z dodatkiem olejku nie różniły się istotnie od wydłużenia i siły rozdzierającej skóry bez dodatku substancji naturalnej. Można zatem stwierdzić, że dodatek olejku w ilości 3% na masę skóry nie będzie miał niekorzystnego wpływu na podstawowe właściwości mechaniczne skór uszlachetnionych tym olejkiem.

3

Steroid signal transduction activated at the cell membrane: from plants to animals.

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Marcinkowska E. , Więdłocha A.

Acta Biochimica Polonica

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2002

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tom 49

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nr 3

735-745

EN

Steroid hormones in plants and in animals are very important for physiological and developmental regulation. In animals steroid hormones are recognized by nuclear receptors, which transcriptionally regulate specific target genes following binding of the ligand. In addition, numerous rapid effects generated by steroids appear to be mediated by a mechanism not depending on the activation of nuclear receptors. Although the existence of separate membrane receptors was postulated many years ago and hundreds of reports supporting this hypothesis have been published, no animal membrane steroid receptor has been cloned to date. Meanwhile, a plant steroid receptor from Arabidopsis thaliana has been identified and cloned. It is a transmembrane protein which specifically recognizes plant steroids (brassinosteroids) at the cell surface and has a serine/threonine protein kinase activity. It seems that plants have no intracellular steroid receptors, since there are no genes homologous to the family of animal nuclear steroid receptors in the genome of A. thaliana. Since the reason of the rapid responses to steroid hormones in animal cells still remains obscure we show in this article two possible explanations of this phenomenon. Using 1,25-dihydroxyvitamin D3 as an example of animal steroid hormone, we review results of our and of other groups concordant with the hypothesis of membrane steroid receptors. We also review the results of experiments performed with ovarian hormones, that led their authors to the hypothesis explaining rapid steroid actions without distinct membrane steroid receptors. Finally, examples of polypeptide growth factor that similarly to steroids exhibit a dual mode of action, activating not only cell surface receptors, but also intracellular targets, are discussed.