Alcohol Interactions with Lipid Bilayers

We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohol's membrane-water partitioning. We have observed clear changes to membrane structure in both transversal and lateral directions. Most importantly, our results suggest the alteration of the membrane-water interface. The water encroachment has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The experimental results have been corroborated by molecular dynamics simulations to reveal further details. Namely, the order parameter profiles have been fruitful in correlating the mechanical model of structural changes to the effect of anesthesia.</p

Środowisko pracy i jego wpływ na występowanie przypadków raka wśród pracowników rafinerii niklu

Objective: To demonstrate an occupation exposure impact on incidence of cancer diseases among nickel smelter workers in Sereď, Slovakia. To analyze the occurrence of cancer diseases among smelter workers. To make a risk assessment and survival analyses in selected group of workers. Methods: Retrospective cohort study is based on data about outcomes of work-related exposures in the present and also on the date about known nickel exposure in the past among smelter workers. Observed historical cohort group were 4622 workers in the nickel smelter in Sereď (Galanta district) who were employed during the years 1963 - 1993. Odds ratio (OR), logistic regression and survival analyses were calculate. Results: There were 1348 non-exposed employees (29%) and 3274 exposed employees (71%). There were 4222 employees without recorded cancer (91%) and 400 employees had recorded cancer disease (9%). Among cancer cases we can assess that they mostly work on manufacture department (52% of cases). The most cases were employed in nickel smelter over the 20 years (42%). The 36% of cases were first time employed in nickel smelter at the age of 31 - 40 years old. With increasing age to start work is increasing chance to be sick (OR = 1,48, CI95% = 1,30 - 1,69, P<0,001). Furthermore, with increasing duration of employment is also higher chance to have cancer (OR = 2,23, CI95% = 2,05 - 2,41, P<0,001). Also the higher risk exposure has impact on higher chance to have cancer (OR = 1,46, CI95% = 1,22 - 1,75, P<0,001). Conclusions: Presented study was the first study, which discussed aspects of the possible occupational exposure in the nickel refinery in Sereď in the Slovak Republic.Cel: Zaprezentowanie wpływu narażenia zawodowego na występowanie chorób nowotworowych u pracowników huty niklu w Sereď, Słowacja. Analiza występowania przypadków zachorowań na raka wśród pracowników huty. Ocena ryzyka zawodowego i analiza przeżycia wybranej grupy pracowników. Metodyka: Retrospektywne badanie kohortowe w oparciu o dane na temat wyników narażeń związanych z obecnym wykonywaniem pracy zawodowej jak i na podstawie rozpoznanych przypadków narażenia zawodowego pracowników huty w przeszłości. Historyczne badania cohortowe obejmowały grupę 4622 pracowników huty niklu w Sereď (okręg Galanta), zatrudnionych w latach 1963 - 1993. Obliczono iloraz szans, regresję logistyczną oraz wykonano analizę przeżycia. Wyniki: Badana grupa obejmowała 1348 (29%) pracowników nie narażonych oraz 3274 narażonych (71%). U 4222 (91%) pracowników nie rozpoznano choroby nowotworowej, raka stwierdzono natomiast u 400 pracowników (9%). Pośród pracowników z wykrytą chorobą nowotworową większość (52% przypadków) była zatrudniona w dziale wytwórczym, przy czym 42% przypadków to osoby o stażu zatrudnienia w hucie niklu przekraczającym 20 lat. 36% zatrudnionych ze stwierdzoną chorobą nowotworową rozpoczęło pracę w hucie w wieku 31 - 40 lat. Wraz ze wzrastającym wiekiem zatrudnienia w hucie wzrasta ryzyko zachorowania na raka (OR = 1,48, CI95% = 1,30 - 1,69, P<0,001). Ponadto, im dłuższy staż pracy tym większe ryzyko raka (OR = 2,23, CI95% = 2,05 - 2,41, P<0,001). Ryzyko to wzrasta też wraz z wydłużeniem okresu narażenia (OR = 1,46, CI95% = 1,22 - 1,75, P ? 0,001). Wnioski: Zaprezentowane badania stanowią pierwszą próbę omówienia aspektów potencjalnego narażenia zawodowego występującego w hucie niklu w Sereď, Słowacja

Alcohol Interactions with Lipid Bilayers

We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohol’s membrane-water partitioning. We have observed clear changes to membrane structure in both transversal and lateral directions. Most importantly, our results suggest the alteration of the membrane-water interface. The water encroachment has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The experimental results have been corroborated by molecular dynamics simulations to reveal further details. Namely, the order parameter profiles have been fruitful in correlating the mechanical model of structural changes to the effect of anesthesia

Influence of cholesterol and beta-sitosterol on the structure of EYPC bilayers

The influence of cholesterol and β-sitosterol on egg yolk phosphatidylcholine (EYPC) bilayers is compared. Different interactions of these sterols with EYPC bilayers were observed using X-ray diffraction. Cholesterol was miscible with EYPC in the studied concentration range (0-50 mol%), but crystallization of β-sitosterol in EYPC bilayers was observed at X ≥ 41 mol% as detected by X-ray diffraction. Moreover, the repeat distance (d) of the lamellar phase was similar upon addition of the two sterols up to mole fraction 17%, while for X ≥ 17 mol% it became higher in the presence of β-sitosterol compared to cholesterol. SANS data on suspensions of unilamellar vesicles showed that both cholesterol and β-sitosterol similarly increase the EYPC bilayer thickness. Cholesterol in amounts above 33 mol% decreased the interlamellar water layer thickness, probably due to "stiffening" of the bilayer. This effect was not manifested by β-sitosterol, in particular due to the lower solubility of β-sitosterol in EYPC bilayers. Applying the formalism of partial molecular areas, it is shown that the condensing effect of both sterols on the EYPC area at the lipid-water interface is small, if any. The parameters of ESR spectra of spin labels localized in different regions of the EYPC bilayer did not reveal any differences between the effects of cholesterol and β-sitosterol in the range of full miscibility