Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 8

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  perturbation
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The expression of transmembrane transporter multidrug resistance-associated protein 1 (MRP1) confers the multidrug-resistant phenotype (MDR) on cancer cells. Since the activity of the other MDR transporter, P-glycoprotein, is sensitive to membrane perturbation, we aimed to check whether the changes in lipid bilayer properties induced by flavones (apigenin, acacetin) and flavonols (morin, myricetin) were related to their MRP1 inhibitory activity. All the flavonoids inhibited the efflux of MRP1 fluorescent substrate from human erythrocytes and breast cancer cells. Morin was also found to stimulate the ATPase activity of erythrocyte ghosts. All flavonoids intercalated into phosphatidylcholine bilayers as judged by differential scanning calorimetry and fluorescence spectroscopy with the use of two carbocyanine dyes. The model of an intramembrane localization for flavones and flavonols was proposed. No clear relationship was found between the membrane-perturbing activity of flavonoids and their potency to inhibit MRP1. We concluded that mechanisms other than perturbation of the lipid phase of membranes were responsible for inhibition of MRP1 by the flavonoids.
The impact of transient wind events on an established zooplankton community was observed during a field survey in a coastal region off northern Norway in May 2002. A transient wind event induced a coastal jet/filament intrusion of warm, saline water into our survey area where a semi-permanent eddy was present. There was an abrupt change in zooplankton community structure within 4–7 days of the wind event, with a change in the size structure, an increase in lower size classes less than 1 mm in equivalent spherical diameter (ESD) and a decrease in larger size classes greater than 1.5 mm in ESD. The slope of zooplankton biovolume spectra changed from −0.6 to −0.8, consistent with the size shifting towards smaller size classes. This study shows that even well established zooplankton communities are susceptible to restructuring during transient wind events, and in particular when wind forcing induces horizontal currents or filaments.
This study continues our investigations concerning the interaction of phenol, catechol, 2,4-dichlorophenol (2,4-DCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4-dimethylphenol (2,4-DMP) with human erythrocytes. We focus on the effects of these compounds on erythrocyte membrane fluidity, as well as on their impact on membrane proteins. The fluorimetric method and fluorescent probes (ANS, DPH and TMA-DPH) were used to estimate the fluidity of erythrocyte membranes. SDS-gel electrophoresis was carried out to separate the proteins of the cell membrane. Additionally, an analysis of disturbances in size and shape of the erythrocytes by the application of the methods of flow cytometry and microscopic examination was performed. It was observed that phenol derivatives like 2,4-DCP, 2,4,5-TCP, 2,4-DMP and catechol induced changes in membrane fluidity and perturbations in the content of a cell’s membrane proteins. Changes in the level of spectrin, band 3 protein and low molecular weight proteins were also noted. Using three fluorescent probes we observed different changes in membrane fluidity on its different layers, depending on the structure and the concentration of the compound used. The application of flow cytometry and microscopic technique also demonstrated disturbances in the size and shape of erythrocytes. We concluded that chlorophenols induced more severe changes in erythrocyte membrane properties and phenol expressed the lowest toxicity.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.