Leptin improves membrane fluidity of erythrocytes in humans via a nitric oxide-dependent mechanism--an electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Kimura, Keizo; Nishio, Ichiro

2002-09-27

Abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. Recently, there has been an indication that leptin, the product of the human obesity gene, actively participates not only in the metabolic regulations but also in the control of cardiovascular functions. In the present study, to assess the role of leptin in the regulation of membrane properties, the effects of leptin on membrane fluidity of erythrocytes in humans are examined. The membrane fluidity of erythrocytes in healthy volunteers by means of an electron paramagnetic resonance (EPR) and spin-labeling method is determined. In an in vitro study, leptin decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner in healthy volunteers. The finding indicated that leptin increased the membrane fluidity and improved the microviscosity of erythrocytes. The effect of leptin on the membrane fluidity was significantly potentiated by the nitric oxide (NO) donors, L-arginine and S-nitroso-N-acetylpenicillamine (SNAP), and a cyclic guanosine monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change evoked by leptin was significantly attenuated in the presence of the NO synthase inhibitors, N(G)-nitro-L-arginine-methyl-ester (L-NAME) and asymmetric dimethyl-L-arginine (ADMA). The results of the present study showed that leptin increased the membrane fluidity and improved the rigidity of cell membranes to some extent via an NO- and cGMP-dependent mechanism. Furthermore, the data also suggest that leptin might have a crucial role in the regulation of rheological behavior of erythrocytes and microcirculation in humans.

Vitamin E supplement improves erythrocyte membrane fluidity of thalassemia: an ESR spin labeling study.

PubMed

Sutipornpalangkul, Werasak; Morales, Noppawan Phumala; Unchern, Supeenun; Sanvarinda, Yupin; Chantharaksri, Udom; Fucharoen, Suthat

2012-01-01

Beta-thalassemia/Hemoglobin E (beta-thal/Hb E) is prevalent in Thailand. The imbalance of globin chains in red blood cells is the primary cause of this anemic disease. The excess alpha-globin in beta-thal/Hb E causes typical damage(s) to membrane of erythroblasts and erythrocytes. By using three paramagnetic labeled compounds (5-, 12-, and 16-spin labeled stearic acids, SLS), the changes of the molecular motion in the lipid bilayer of thalassemic RBCs that have structural modification can be detected. to investigate erythrocyte membrane fluidity and the effect of vitamin E treatment in beta-thalassemia/Hemoglobin E patients by using spin labeling techniques. The erythrocyte membrane fluidity was investigated in nine splenectomized and five non-splenectomized beta-thalassemia/hemoglobin E (beta-thal/Hb E) patients using EPR spin labeling techniques. To determine the effect of vitamin E on erythrocyte membrane fluidity, only the splenectomized patients were enrolled. Patients were divided into two groups. The first group received 350 mg vitamin E daily for a period of 1 month (n = 5) and the second group received placebo for an equal period (n = 4). Three paramagnetic fatty acid, 5-, 12-, and 16-doxyl stearic acids, (5-, 12- and 16-DS) were used to label phospholipids layer near both the surface (5-DS) and the deeper hydrophobic region of membrane (12-and 16-DS). Lipid peroxidation (TBARs) was measured using a colorimetric method. Vitamin E was measured with high performance liquid chromatography (HPLC). Significantly higher values of erythrocyte membrane fluidity were revealed with 12-, 16-DS in splenectomized patients, as compared with non-splenectomized patients and normal subjects. In 3-thal/Hb E patients, fluidity values, both outer hyperfine splitting (2T(//)) and order parameter (S) of 12-DS showed inverse correlation with serum TBARs. There was no significant difference between the fluidity values measured with 5-DS. After vitamin E supplementation, the erythrocyte membrane fluidity was decreased in almost all patients. In contrast to the vitamin E supplementation group, increased erythrocyte membrane fluidity was demonstrated in the placebo group. Vitamin E supplementation also had effect on other clinical parameters such as increased plasma vitamin E, decreased serum TBARs and no change in hemoglobin. The present results suggested the abnormal motion of lipid in the deeper phospholipids region of membrane. In addition, vitamin E supplementation may have a role in the prevention of erythrocyte membrane damage of these patients.

Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

PubMed Central

Santhosh, Poornima Budime; Drašler, Barbara; Drobne, Damjana; Kreft, Mateja Erdani; Kralj, Slavko; Makovec, Darko; Ulrih, Nataša Poklar

2015-01-01

Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications. PMID:26491286

Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Degreif, Daniel; de Rond, Tristan; Bertl, Adam

Cells modulate lipid metabolism in order to maintain membrane homeostasis. In this paper, we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggered cell-cell adhesion (flocculation), a phenomenon characteristic of industrial yeast but uncommon in laboratory strains. We find that ER lipid saturation sensors induce expression of FLO1 – encoding a cell wall polysaccharide binding protein – independently of its canonical regulator. In wild-type cells, Flo1p-dependent flocculation occurs under oxygen-limited growth, which reduces unsaturated lipid synthesis and thus serves as the environmentalmore » trigger for flocculation. Transcriptional analysis shows that FLO1 is one of the most highly induced genes in response to changes in lipid unsaturation, and that the set of membrane fluidity-sensitive genes is globally activated as part of the cell's long-term response to hypoxia during fermentation. Finally, our results show how the lipid homeostasis machinery of budding yeast is adapted to carry out a broad response to an environmental stimulus important in biotechnology.« less

Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth.

PubMed

Degreif, Daniel; de Rond, Tristan; Bertl, Adam; Keasling, Jay D; Budin, Itay

2017-05-01

Cells modulate lipid metabolism in order to maintain membrane homeostasis. Here we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggered cell-cell adhesion (flocculation), a phenomenon characteristic of industrial yeast but uncommon in laboratory strains. We find that ER lipid saturation sensors induce expression of FLO1 - encoding a cell wall polysaccharide binding protein - independently of its canonical regulator. In wild-type cells, Flo1p-dependent flocculation occurs under oxygen-limited growth, which reduces unsaturated lipid synthesis and thus serves as the environmental trigger for flocculation. Transcriptional analysis shows that FLO1 is one of the most highly induced genes in response to changes in lipid unsaturation, and that the set of membrane fluidity-sensitive genes is globally activated as part of the cell's long-term response to hypoxia during fermentation. Our results show how the lipid homeostasis machinery of budding yeast is adapted to carry out a broad response to an environmental stimulus important in biotechnology. Copyright © 2017 International Metabolic Engineering Society. All rights reserved.

Short infrared laser pulses increase cell membrane fluidity

NASA Astrophysics Data System (ADS)

Walsh, Alex J.; Cantu, Jody C.; Ibey, Bennett L.; Beier, Hope T.

2017-02-01

Short infrared laser pulses induce a variety of effects in cells and tissues, including neural stimulation and inhibition. However, the mechanism behind these physiological effects is poorly understood. It is known that the fast thermal gradient induced by the infrared light is necessary for these biological effects. Therefore, this study tests the hypothesis that the fast thermal gradient induced in a cell by infrared light exposure causes a change in the membrane fluidity. To test this hypothesis, we used the membrane fluidity dye, di-4-ANEPPDHQ, to investigate membrane fluidity changes following infrared light exposure. Di-4-ANEPPDHQ fluorescence was imaged on a wide-field fluorescence imaging system with dual channel emission detection. The dual channel imaging allowed imaging of emitted fluorescence at wavelengths longer and shorter than 647 nm for ratiometric assessment and computation of a membrane generalized polarization (GP) value. Results in CHO cells show increased membrane fluidity with infrared light pulse exposure and this increased fluidity scales with infrared irradiance. Full recovery of pre-infrared exposure membrane fluidity was observed. Altogether, these results demonstrate that infrared light induces a thermal gradient in cells that changes membrane fluidity.

The fluidity of Chinese hamster ovary cell and bull sperm membranes after cholesterol addition.

PubMed

Purdy, P H; Fox, M H; Graham, J K

2005-08-01

Cell plasma membrane fluidity is affected by membrane lipid and protein composition as well as temperature. Altering the cholesterol content of a membrane can change membrane fluidity at different temperatures and this may affect cell survival during cryopreservation. In these experiments, we examined the effect that adding cholesterol to the membranes of Chinese hamster ovary cells (CHO) and bull sperm had on cell plasma membrane fluidity and cell survival when cells were cooled to 5 degrees C or were cryopreserved. Cells were treated with 0, 1.5 or 5.0mg cholesterol-loaded cyclodextrin (CLC), stained with N-((4-(6-phenyl-1,3,5-hexatrienyl)phenyl)propyl)trimethylammonium-p-toluenesulfonate (TMAP-DPH) to evaluate membrane fluidity and with propidium iodide to evaluate cell viability, prior to analysis by flow cytometry at 23, 5 degrees C, and after cryopreservation. CHO cells exhibited a single cell population with all cells having similar membrane fluidity. Membrane fluidity did not change when temperature had been reduced and then returned to 23 degrees C (P<0.05), however, adding cholesterol to the cells induced membranes to become more rigid (P<0.05). Bull sperm samples consisted of two cell subpopulations, one having relatively higher membrane fluidity than the other, regardless of cholesterol treatment or temperature. In addition, cells possessing the highest membrane fluidity did not survive cooling or cryopreservation efficiently. CLC treatment did not significantly alter membrane fluidity after temperature changes, but did maintain higher percentages of spermatozoa surviving cooling to 5 degrees C and cryopreservation (P<0.05). In conclusion, adding cholesterol to cell resulted in detectable membrane fluidity changes in CHO cells and increased survival of bull sperm after cooling to 5 degrees C and after cryopreservation.

Hydrostatic pressure decreases membrane fluidity and lipid desaturase expression in chondrocyte progenitor cells.

PubMed

Montagne, Kevin; Uchiyama, Hiroki; Furukawa, Katsuko S; Ushida, Takashi

2014-01-22

Membrane biomechanical properties are critical in modulating nutrient and metabolite exchange as well as signal transduction. Biological membranes are predominantly composed of lipids, cholesterol and proteins, and their fluidity is tightly regulated by cholesterol and lipid desaturases. To determine whether such membrane fluidity regulation occurred in mammalian cells under pressure, we investigated the effects of pressure on membrane lipid order of mouse chondrogenic ATDC5 cells and desaturase gene expression. Hydrostatic pressure linearly increased membrane lipid packing and simultaneously repressed lipid desaturase gene expression. We also showed that cholesterol mimicked and cholesterol depletion reversed those effects, suggesting that desaturase gene expression was controlled by the membrane physical state itself. This study demonstrates a new effect of hydrostatic pressure on mammalian cells and may help to identify the molecular mechanisms involved in hydrostatic pressure sensing in chondrocytes. © 2013 Elsevier Ltd. All rights reserved.

Solanum Nigrum polysaccharide (SNL) extract effects in transplanted tumor-bearing mice--erythrocyte membrane fluidity and blocking of functions.

PubMed

Yuan, Hong-Liang; Liu, Xiao-Lei; Liu, Ying-Jie

2014-01-01

Solanum nigrum L. has been used in traditional Chinese medicine because of its diuretic and antipyretic effects. The present research concerned effects of crude polysaccharides isolated from Solanum nigrum L. on erythrocyte membranes of tumor-bearing S180 and H22 in mice. Fluorescence- labeled red blood cell membranes were used with DPH fluorescence spectrophotometry to examine erythrocyte membrane fluidity, and colorimetry to determine degree of erythrocyte surface membrane blocking. Extent of reaction by tumor-bearing mice with the enzyme erythrocyte membrane bubble shadow detection of red cell membrane variation in the degree of closure before and after administration. Solanum nigrum polysaccharide could significantly improve the S180 and H22 tumor-bearing mice erythrocyte membrane fluidity, compared with the control group, the difference was significant (p<0.01), SNL can significantly improve the red blood cell membrane and then S180 tumor-bearing mice sealing ability, compared with the negative control group, the difference was significant(p<0.05, p<0.01). H22 tumor-bearing mice can increase red cell membrane and then sealing ability, the difference was significant (p<0.05). Solanum nigrum polysaccharide degree of fluidity and blocking two transplanted tumors in mice restored the ability to raise the red cell membrane has a significant effect. Solanum nigrum L.-type mice transplanted tumor can affect the red blood cell membrane fluidity and re-closed, through the red cell membrane of red blood cells to enhance the immune function of the possibility of erythrocyte immunity against tumor formation garland provide experimental basis.

Possible evolutionary origins of human female sexual fluidity.

PubMed

Kanazawa, Satoshi

2017-08-01

I propose an evolutionary theory of human female sexual fluidity and argue that women may have been evolutionarily designed to be sexually fluid in order to allow them to have sex with their cowives in polygynous marriage and thus reduce conflict and tension inherent in such marriage. In addition to providing an extensive definition and operationalization of the concept of sexual fluidity and specifying its ultimate function for women, the proposed theory can potentially solve several theoretical and empirical puzzles in evolutionary psychology and sex research. Analyses of the National Longitudinal Study of Adolescent Health (Add Health) confirm the theory's predictions that: (i) women (but not men) who experience increased levels of sexual fluidity have a larger number of children (suggesting that female sexual fluidity, if heritable, may be evolutionarily selected); (ii) women (but not men) who experience marriage or parenthood early in adult life subsequently experience increased levels of sexual fluidity; and (iii) sexual fluidity is significantly positively correlated with known markers of unrestricted sexual orientation among women whereas it is significantly negatively correlated with such markers among men. © 2016 Cambridge Philosophical Society.

Roles of pyruvate dehydrogenase and branched-chain α-keto acid dehydrogenase in branched-chain membrane fatty acid levels and associated functions in Staphylococcus aureus.

PubMed

Singh, Vineet K; Sirobhushanam, Sirisha; Ring, Robert P; Singh, Saumya; Gatto, Craig; Wilkinson, Brian J

2018-04-01

Membrane fluidity to a large extent is governed by the presence of branched-chain fatty acids (BCFAs). Branched-chain α-keto acid dehydrogenase (BKD) is the key enzyme in BCFA synthesis. A Staphylococcus aureus BKD-deficient strain still produced substantial levels of BCFAs. Pyruvate dehydrogenase (PDH) with structural similarity to BKD has been speculated to contribute to BCFAs in S. aureus. This study was carried out using BKD-, PDH- and BKD : PDH-deficient derivatives of methicillin-resistant S. aureus strain JE2. Differences in growth kinetics were evaluated spectrophotometrically, membrane BCFAs using gas chromatography and membrane fluidity by fluorescence polarization. Carotenoid levels were estimated by measuring A465 of methanol extracts from 48 h cultures. MIC values were determined by broth microdilution.Results/Key findings. BCFAs made up 50 % of membrane fatty acids in wild-type but only 31 % in the BKD-deficient mutant. BCFA level was ~80 % in the PDH-deficient strain and 38 % in the BKD : PDH-deficient strain. BKD-deficient mutant showed decreased membrane fluidity, the PDH-deficient mutant showed increased membrane fluidity. The BKD- and PDH-deficient strains grew slower and the BKD : PDH-deficient strain grew slowest at 37 °C. However at 20 °C, the BKD- and BKD : PDH-deficient strains grew only a little followed by autolysis of these cells. The BKD-deficient strain produced higher levels of staphyloxanthin. The PDH-deficient and BKD : PDH-deficient strains produced very little staphyloxanthin. The BKD-deficient strain showed increased susceptibility to daptomycin. The BCFA composition of the cell membrane in S. aureus seems to significantly impact cell growth, membrane fluidity and resistance to daptomycin.

PAQR-2 Regulates Fatty Acid Desaturation during Cold Adaptation in C. elegans

PubMed Central

Svensk, Emma; Ståhlman, Marcus; Andersson, Carl-Henrik; Johansson, Maja; Borén, Jan; Pilon, Marc

2013-01-01

C. elegans PAQR-2 is homologous to the insulin-sensitizing adiponectin receptors in mammals, and essential for adaptation to growth at 15°C, a low but usually acceptable temperature for this organism. By screening for novel paqr-2 suppressors, we identified mutations in genes involved in phosphatidylcholine synthesis (cept-1, pcyt-1 and sams-1) and fatty acid metabolism (ech-7, hacd-1, mdt-15, nhr-49 and sbp-1). We then show genetic evidence that paqr-2, phosphatidylcholines, sbp-1 and Δ9-desaturases form a cold adaptation pathway that regulates the increase in unsaturated fatty acids necessary to retain membrane fluidity at low temperatures. This model is supported by the observations that the paqr-2 suppressors normalize the levels of saturated fatty acids, and that low concentrations of detergents that increase membrane fluidity can rescue the paqr-2 mutant. PMID:24068966

PAQR-2 regulates fatty acid desaturation during cold adaptation in C. elegans.

PubMed

Svensk, Emma; Ståhlman, Marcus; Andersson, Carl-Henrik; Johansson, Maja; Borén, Jan; Pilon, Marc

2013-01-01

C. elegans PAQR-2 is homologous to the insulin-sensitizing adiponectin receptors in mammals, and essential for adaptation to growth at 15°C, a low but usually acceptable temperature for this organism. By screening for novel paqr-2 suppressors, we identified mutations in genes involved in phosphatidylcholine synthesis (cept-1, pcyt-1 and sams-1) and fatty acid metabolism (ech-7, hacd-1, mdt-15, nhr-49 and sbp-1). We then show genetic evidence that paqr-2, phosphatidylcholines, sbp-1 and Δ9-desaturases form a cold adaptation pathway that regulates the increase in unsaturated fatty acids necessary to retain membrane fluidity at low temperatures. This model is supported by the observations that the paqr-2 suppressors normalize the levels of saturated fatty acids, and that low concentrations of detergents that increase membrane fluidity can rescue the paqr-2 mutant.

Effects of Insecticides on the Fluidity of Mitochondrial Membranes of the Diamondback Moth, Plutella xylostella, Resistant and Susceptible to Avermectin

PubMed Central

Hu, J.; Liang, P.; Shi, X.; Gao, X.

2008-01-01

The effects of various insecticides on the fluidity of mitochondrial membranes and cross-resistance were investigated in the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) using strains that were both resistant and susceptible to avermectin. The resistant strain of P. xylostella, AV-R, developed 1078-fold resistance to avermetins with a high level of cross-resistance to the analogs of avermectins, ivermectin and emamectin benzoate. It had more than 1000 times greater resistance when compared with the avermectin-susceptible strain, XH-S. Mitochondrial membrane fluidity was measured by detecting fluorescence polarization using DPH (1,6-Diphenyl -1,3,5-hexatriene) as the fluorescence probe. Abamectin, emamectin benzoate, ivermectin, cypermethrin and fenvalerate decreased the fluidity of mitochondrial membranes in the XH-S strain at 25°C. However, fipronil and acephate did not change the fluidity of mitochondrial membrane when the concentration of these insecticides was 1×10-4 mol/L. Membrane fluidity increased as the temperature increased. The thermotropic effect on the polarization value of DPH increased as the insecticide concentration was increased. There was a significant difference of mitochondrial membrane fluidity between both XH-S and AV-R when temperature was less than 25°C and no difference was observed when the temperature was more than 25°C. The low-dose abamectin (0.11 mg/L) in vivo treatment caused a significant change of membrane fluidity in the XH-S strain and no change in the AV-R strain. However, a high-dose abamectin (11.86 mg/L) resulted in 100% mortality of the XH-S strain. In vivo treatment may cause a significant change of membrane fluidity in the AV-R strain PMID:20345311

The directional response of chemotactic cells depends on a balance between cytoskeletal architecture and the external gradient.

PubMed

Wang, Ming-Jie; Artemenko, Yulia; Cai, Wen-Jie; Iglesias, Pablo A; Devreotes, Peter N

2014-11-06

Polarized migrating cells display signal transduction events, such as activation of phosphatidylinositol 3-kinase (PI3K) and Scar/Wave, and respond more readily to chemotactic stimuli at the leading edge. We sought to determine the basis of this polarized sensitivity. Inhibiting actin polymerization leads to uniform sensitivity. However, when human neutrophils were "stalled" by simultaneously blocking actin and myosin dynamics, they maintained the gradient of responsiveness to chemoattractant and also displayed noise-driven PIP3 flashes on the basal membrane, localized toward the front. Thus, polarized sensitivity does not require migration or cytoskeletal dynamics. The threshold for response is correlated with the static F-actin distribution, but not cell shape or volume changes, membrane fluidity, or the preexisting distribution of PI3K. The kinetics of responses to temporal and spatial stimuli were consistent with the local excitation global inhibition model, but the overall direction of the response was biased by the internal axis of polarity. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Phospholipid bilayer-perturbing properties underlying lysis induced by pH-sensitive cationic lysine-based surfactants in biomembranes.

PubMed

Nogueira, Daniele Rubert; Mitjans, Montserrat; Busquets, M Antonia; Pérez, Lourdes; Vinardell, M Pilar

2012-08-14

Amino acid-based surfactants constitute an important class of natural surface-active biomolecules with an unpredictable number of industrial applications. To gain a better mechanistic understanding of surfactant-induced membrane destabilization, we assessed the phospholipid bilayer-perturbing properties of new cationic lysine-based surfactants. We used erythrocytes as biomembrane models to study the hemolytic activity of surfactants and their effects on cells' osmotic resistance and morphology, as well as on membrane fluidity and membrane protein profile with varying pH. The antihemolytic capacity of amphiphiles correlated negatively with the length of the alkyl chain. Anisotropy measurements showed that the pH-sensitive surfactants, with the positive charge on the α-amino group of lysine, significantly increased membrane fluidity at acidic conditions. SDS-PAGE analysis revealed that surfactants induced significant degradation of membrane proteins in hypo-osmotic medium and at pH 5.4. By scanning electron microscopy examinations, we corroborated the interaction of surfactants with lipid bilayer. We found that varying the surfactant chemical structure is a way to modulate the positioning of the molecule inside bilayer and, thus, the overall effect on the membrane. Our work showed that pH-sensitive lysine-based surfactants significantly disturb the lipid bilayer of biomembranes especially at acidic conditions, which suggests that these compounds are promising as a new class of multifunctional bioactive excipients for active intracellular drug delivery.

Effect of plasma membrane fluidity on serotonin transport by endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Block, E.R.; Edwards, D.

1987-11-01

To evaluate the effect of plasma membrane fluidity of lung endothelial cells on serotonin transport, porcine pulmonary artery endothelial cells were incubated for 3 h with either 0.1 mM cholesterol hemisuccinate, 0.1 mM cis-vaccenic acid, or vehicle (control), after which plasma membrane fluidity and serotinin transport were measured. Fluorescence spectroscopy was used to measure fluidity in the plasma membrane. Serotonin uptake was calculated from the disappearance of ({sup 14}C)-serotonin from the culture medium. Cholesterol decreased fluidity in the subpolar head group and central and midacyl side-chain regions of the plasma membrane and decreased serotonin transport, whereas cis-vaccenic acid increased fluiditymore » in the central and midacyl side-chain regions of the plasma membrane and also increased serotonin transport. Cis-vaccenic acid had no effect of fluidity in the subpolar head group region of the plasma membrane. These results provide evidence that the physical state of the central and midacyl chains within the pulmonary artery endothelial cell plasma membrane lipid bilayer modulates transmembrane transport of serotonin by these cells.« less

Aniracetam restores the effects of amyloid-beta protein or ageing on membrane fluidity and intracellular calcium concentration in mice synaptosomes.

PubMed

Li, Y; Wang, J-J; Cai, J-X

2007-01-01

In the present study, we observed the in vitro effect of aniracetam on membrane fluidity and free calcium concentrations ([Ca(2+)]i) of frontal cortical (FC) and hippocampal (HP) synaptosomes of aged mice and young mice treated with amyloid-beta protein (Abeta) Membrane fluidity was measured by using fluorescence anisotropy of the lipophilic probe, 1,6-diphenyl-1,3,5-hexatriene (DPH). [Ca(2+)]i was measured by using Fura 2-AM fluorescent spectrophotometry. We found that membrane fluidity of the FC and HP synaptosomes was decreased in 14 months old mice compared with that in 3 months old mice. Similarly, Abeta25-35 (1 microM) decreased the membrane fluidity in 3 months old mice. These effects of ageing and Abeta25-35 on membrane fluidity were restored by aniracetam in a concentration-dependent manner. Furthermore, Abeta25-35 (1 microM) largely increased [Ca(2+)]i in FC and HP synaptosomes in 3 months old mice, but this effect on HP synaptosomes was effectively reversed by aniracetam (1-4 mM). The present findings suggest that aniracetam restores age- and Abeta-induced alterations in membrane fluidity or Abeta-induced increase in [Ca(2+)]i, demonstrating a possible beneficial role of aniracetam in the clinic treatment for senile dementia or Alzheimer's disease.

Microscopic mechanism analyses on influence of metabolism of erythrocyte membrane-lipid etc. by LLLIB

NASA Astrophysics Data System (ADS)

Xu, Lin; Zhang, Canbang; Wen, Yuanbin; Liu, Shuxiao; Zhou, Lingyun

2009-08-01

Some cases with cerebral infarction were treated by He-Ne laser irradiation on blood. In the treatment before and after, membrane-cholesterol(C)/membrane-phosphatide(P), membrane fluidity(F) and deformability of erythrocyte were determined. The results showed that low level laser irradiation on blood (LLLIB) can sure reduce the ratio of (C)/(P), can heighten fluidity and improve deformability of erythrocyte .Thus the metabolism ability of erythrocyte membrane-lipid ,the blood circulation and the properties of hemorheology can be improved. In this paper, the microscopic mechanism of those aforesaid action effects by low level laser irradiation on blood were analyzed by means of Quantum theory and some corresponding models.

Effects of causality on the fluidity and viscous horizon of quark-gluon plasma

NASA Astrophysics Data System (ADS)

Rahaman, Mahfuzur; Alam, Jan-e.

2018-05-01

The second-order Israel-Stewart-M u ̈ller relativistic hydrodynamics was applied to study the effects of causality on the acoustic oscillation in relativistic fluid. Causal dispersion relations have been derived with nonvanishing shear viscosity, bulk viscosity, and thermal conductivity at nonzero temperature and baryonic chemical potential. These relations have been used to investigate the fluidity of quark-gluon plasma (QGP) at finite temperature (T ). Results of the first-order dissipative hydrodynamics have been obtained as a limiting case of the second-order theory. The effects of the causality on the fluidity near the transition point and on the viscous horizon are found to be significant. We observe that the inclusion of causality increases the value of fluidity measure of QGP near Tc and hence makes the flow strenuous. It was also shown that the inclusion of the large magnetic field in the causal hydrodynamics alters the fluidity of QGP.

Interrelationships between Fatty Acid Composition, Staphyloxanthin Content, Fluidity, and Carbon Flow in the Staphylococcus aureus Membrane.

PubMed

Tiwari, Kiran B; Gatto, Craig; Wilkinson, Brian J

2018-05-17

Fatty acids play a major role in determining membrane biophysical properties. Staphylococcus aureus produces branched-chain fatty acids (BCFAs) and straight-chain saturated fatty acids (SCSFAs), and can directly incorporate exogenous SCSFAs and straight-chain unsaturated fatty acids (SCUFAs). Many S. aureus strains produce the triterpenoid pigment staphyloxanthin, and the balance of BCFAs, SCSFAs and staphyloxanthin determines membrane fluidity. Here, we investigated the relationship of fatty acid and carotenoid production in S. aureus using a pigmented strain (Pig1), its carotenoid-deficient mutant (Pig1Δ crtM ) and the naturally non-pigmented Staphylococcus argenteus that lacks carotenoid biosynthesis genes and is closely related to S. aureus . Fatty acid compositions in all strains were similar under a given culture condition indicating that staphyloxanthin does not influence fatty acid composition. Strain Pig1 had decreased membrane fluidity as measured by fluorescence anisotropy compared to the other strains under all conditions indicating that staphyloxanthin helps maintain membrane rigidity. We could find no evidence for correlation of expression of crtM and fatty acid biosynthesis genes. Supplementation of medium with glucose increased SCSFA production and decreased BCFA and staphyloxanthin production, whereas acetate-supplementation also decreased BCFAs but increased staphyloxanthin production. We believe that staphyloxanthin levels are influenced more through metabolic regulation than responding to fatty acids incorporated into the membrane.

Plasmonic Techniques for Viral Membrane Characterization

NASA Astrophysics Data System (ADS)

Feizpour, Amin

The lipid bilayer membrane of enveloped viruses, such as human immunodeficiency virus type 1 (HIV-1), plays an important role in key steps of the infection, including cell binding and uptake. Phosphatidylserine (PS) and monosialotetrahexosylganglioside (GM1) are examples of two host-derived lipids in the membrane of enveloped virus particles that are known to contribute to virus attachment, uptake, and ultimately dissemination. A quantitative characterization of their contribution to the functionality of the virus requires information about their relative concentrations in the viral membrane. In this dissertation, a gold nanoparticle (NP) binding assay for probing relative PS and GM1 lipid concentrations in the outer leaflet of different virus-like particles (VLPs) using small sample sizes is introduced. The assay evaluates both scattering intensity and resonance wavelength and determines relative NP densities through plasmon coupling as a measure for the target lipid concentrations in the NP-labeled VLP membrane. The performed studies reveal significant differences in the membrane of HIV-1 and Ebola VLPs that assemble at different intracellular sites and pave the way to an optical quantification of lipid concentration in virus particles at physiological titers. In addition, this technique was used in another application to improve the understanding of the relationship between the membrane PS lipid and the infectivity of HIV-2 and murine leukemia virus (MLV). The composition of the membrane, in particular the cholesterol (chol) content, determines its fluidity. As differences in the membrane composition of individual virus particles can lead to different intracellular fates, biophysical tools capable of probing the membrane fluidity on the single-virus level are required. In this dissertation, we demonstrate that fluctuations in the polarization of light scattered off gold or silver nanoparticle (NP)-labeled virus-like-particles (VLPs) encode information about the membrane fluidity of individual VLPs. We developed a plasmonic polarization fluctuation tracking microscopy (PFTM) which facilitated, for the first time, the investigation of the effect of chol content on the membrane fluidity and its dependence on temperature on the single-VLP level. Chol extraction studies with different methyl-beta-cyclodextrin (MbetaCD) concentrations yielded a gradual decrease in polarization fluctuations as function of time. The PFTM revealed chol content and fluidity heterogeneities of an HIV-1 VLP population.

Between Scylla and Charybdis: Hydrophobic Graphene-Guided Water Diffusion on Hydrophilic Substrates

PubMed Central

Kim, Jin-Soo; Choi, Jin Sik; Lee, Mi Jung; Park, Bae Ho; Bukhvalov, Danil; Son, Young-Woo; Yoon, Duhee; Cheong, Hyeonsik; Yun, Jun-Nyeong; Jung, Yousung; Park, Jeong Young; Salmeron, Miquel

2013-01-01

The structure of water confined in nanometer-sized cavities is important because, at this scale, a large fraction of hydrogen bonds can be perturbed by interaction with the confining walls. Unusual fluidity properties can thus be expected in the narrow pores, leading to new phenomena like the enhanced fluidity reported in carbon nanotubes. Crystalline mica and amorphous silicon dioxide are hydrophilic substrates that strongly adsorb water. Graphene, on the other hand, interacts weakly with water. This presents the question as to what determines the structure and diffusivity of water when intercalated between hydrophilic substrates and hydrophobic graphene. Using atomic force microscopy, we have found that while the hydrophilic substrates determine the structure of water near its surface, graphene guides its diffusion, favouring growth of intercalated water domains along the C-C bond zigzag direction. Molecular dynamics and density functional calculations are provided to help understand the highly anisotropic water stripe patterns observed. PMID:23896759

Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi.

PubMed

Turk, Martina; Méjanelle, Laurence; Sentjurc, Marjeta; Grimalt, Joan O; Gunde-Cimerman, Nina; Plemenitas, Ana

2004-02-01

The halophilic melanized yeast-like fungi Hortaea werneckii, Phaeotheca triangularis, and the halotolerant Aureobasidium pullulans, isolated from salterns as their natural environment, were grown at different NaCl concentrations and their membrane lipid composition and fluidity were examined. Among sterols, besides ergosterol, which was the predominant one, 23 additional sterols were identified. Their total content did not change consistently or significantly in response to raised NaCl concentrations in studied melanized fungi. The major phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, followed by anionic phospholipids. The most abundant fatty acids in phospholipids contained C16 and C18 chain lengths with a high percentage of C18:2Delta9,12. Salt stress caused an increase in the fatty acid unsaturation in the halophilic H. werneckii and halotolerant A. pullulans but a slight decrease in halophilic P. triangularis. All the halophilic fungi maintained their sterol-to-phospholipid ratio at a significantly lower level than did the salt-sensitive Saccharomyces cerevisiae and halotolerant A. pullulans. Electron paramagnetic resonance (EPR) spectroscopy measurements showed that the membranes of all halophilic fungi were more fluid than those of the halotolerant A. pullulans and salt-sensitive S. cerevisiae, which is in good agreement with the lipid composition observed in this study.

Mechanical Fluidity of Fully Suspended Biological Cells

PubMed Central

Maloney, John M.; Lehnhardt, Eric; Long, Alexandra F.; Van Vliet, Krystyn J.

2013-01-01

Mechanical characteristics of single biological cells are used to identify and possibly leverage interesting differences among cells or cell populations. Fluidity—hysteresivity normalized to the extremes of an elastic solid or a viscous liquid—can be extracted from, and compared among, multiple rheological measurements of cells: creep compliance versus time, complex modulus versus frequency, and phase lag versus frequency. With multiple strategies available for acquisition of this nondimensional property, fluidity may serve as a useful and robust parameter for distinguishing cell populations, and for understanding the physical origins of deformability in soft matter. Here, for three disparate eukaryotic cell types deformed in the suspended state via optical stretching, we examine the dependence of fluidity on chemical and environmental influences at a timescale of ∼1 s. We find that fluidity estimates are consistent in the time and frequency domains under a structural damping (power-law or fractional-derivative) model, but not under an equivalent-complexity, lumped-component (spring-dashpot) model; the latter predicts spurious time constants. Although fluidity is suppressed by chemical cross-linking, we find that ATP depletion in the cell does not measurably alter the parameter, and we thus conclude that active ATP-driven events are not a crucial enabler of fluidity during linear viscoelastic deformation of a suspended cell. Finally, by using the capacity of optical stretching to produce near-instantaneous increases in cell temperature, we establish that fluidity increases with temperature—now measured in a fully suspended, sortable cell without the complicating factor of cell-substratum adhesion. PMID:24138852

Role of cytoskeletal mechanics and cell membrane fluidity in the intracellular delivery of molecules mediated by laser-activated carbon nanoparticles.

PubMed

Holguin, Stefany Y; Anderson, Caleb F; Thadhani, Naresh N; Prausnitz, Mark R

2017-10-01

Exposure of cells and nanoparticles to near-infrared nanosecond pulsed laser light can lead to efficient intracellular delivery of molecules while maintaining high cell viability by a photoacoustic phenomenon known as transient nanoparticle energy transduction (TNET). Here, we examined the influence of cytoskeletal mechanics and plasma membrane fluidity on intracellular uptake of molecules and loss of cell viability due to TNET. We found that destabilization of actin filaments using latrunculin A led to greater uptake of molecules and less viability loss caused by TNET. Stabilization of actin filaments using jasplakinolide had no significant effect on uptake or viability loss caused by TNET. To study the role of plasma membrane fluidity, we increased fluidity by depletion of membrane cholesterol using methyl-β-cyclodextrin and decreased fluidity by enrichment of the membrane with cholesterol using water-soluble cholesterol. Neither of these membrane fluidity changes significantly altered cellular uptake or viability loss caused by TNET. We conclude that weakening mechanical integrity of the cytoskeleton can increase intracellular uptake and decrease loss of cell viability, while plasma membrane fluidity does not appear to play a significant role in uptake or viability loss caused by TNET. The positive effects of cytoskeletal weakening may be due to an enhanced ability of the cell to recover from the effects of TNET and maintain viability. Biotechnol. Bioeng. 2017;114: 2390-2399. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Liver mitochondrial membrane fluidity at early development of diabetes and its correlation with the respiration.

PubMed

Pérez-Hernández, Ismael H; Domínguez-Fuentes, Josué Misael; Palomar-Morales, Martín; Zazueta-Mendizabal, Ana Cecilia; Baiza-Gutman, Arturo; Mejía-Zepeda, Ricardo

2017-06-01

The biological membranes are important in cell function but, during development of diseases such as diabetes, they are impaired. Consequently, membrane-associated biological processes are impaired as well. The mitochondria are important organelles where oxidative phosphorylation takes place, a process closely related with the membranes. In general, it is accepted that the development process of diabetes decreases membrane fluidity. However, in some cases, it has been found to increase membrane fluidity of mitochondria but to decrease the Respiratory Control (RC) index. In this study we found an increase of membrane fluidity and an increase of the RC at an early phase of the development of a type 2 diabetes model. We measured the lipoperoxidation, analyzed the fatty acids composition by gas chromatography, and assessed membrane fluidity using three fluorescent monitors located at different depths inside the bilayer, dipyrenilpropane (DPyP), diphenylhexatriene (DPH), and trimethylammonium diphenylhexatriene (TMA-DPH). Our findings indicate that in the initial stage of diabetes development, when lipoperoxidation still is not significant, the membrane fluidity of liver mitochondria increases because of the increment in the unsaturated to saturated fatty acids ratio (U/S), thus producing an increase of the RC. The membrane fluidity is not the same at all depths in the bilayer. Contrary to the results obtained in mitochondria, the diabetes induced a decrease in the U/S fatty acids ratio of liver total lipids, indicating that the mitochondria might have an independent mechanism for regulating its fatty acids composition.

Inheritance pattern of platelet membrane fluidity in Alzheimer disease.

PubMed Central

Chakravarti, A; Slaugenhaupt, S A; Zubenko, G S

1989-01-01

The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in labeled platelet membranes, an index of membrane fluidity, is a stable, familial trait that is associated with a clinically distinct subtype of Alzheimer disease. Complex segregation analysis of this continuous variable was performed on 95 members of 14 pedigrees identified through probands who had autopsy-confirmed or clinically diagnosed Alzheimer disease. The results suggest that platelet membrane fluidity is controlled by a single genetic locus, PMF, with two alleles that have additive effects. The PMF locus appears to explain approximately 80% of the total variation in platelet membrane fluidity within the families of patients with Alzheimer disease. PMID:2729275

Membrane fluidity controls redox-regulated cold stress responses in cyanobacteria.

PubMed

Maksimov, Eugene G; Mironov, Kirill S; Trofimova, Marina S; Nechaeva, Natalya L; Todorenko, Daria A; Klementiev, Konstantin E; Tsoraev, Georgy V; Tyutyaev, Eugene V; Zorina, Anna A; Feduraev, Pavel V; Allakhverdiev, Suleyman I; Paschenko, Vladimir Z; Los, Dmitry A

2017-09-01

Membrane fluidity is the important regulator of cellular responses to changing ambient temperature. Bacteria perceive cold by the transmembrane histidine kinases that sense changes in thickness of the cytoplasmic membrane due to its rigidification. In the cyanobacterium Synechocystis, about a half of cold-responsive genes is controlled by the light-dependent transmembrane histidine kinase Hik33, which also partially controls the responses to osmotic, salt, and oxidative stress. This implies the existence of some universal, but yet unknown signal that triggers adaptive gene expression in response to various stressors. Here we selectively probed the components of photosynthetic machinery and functionally characterized the thermodynamics of cyanobacterial photosynthetic membranes with genetically altered fluidity. We show that the rate of oxidation of the quinone pool (PQ), which interacts with both photosynthetic and respiratory electron transport chains, depends on membrane fluidity. Inhibitor-induced stimulation of redox changes in PQ triggers cold-induced gene expression. Thus, the fluidity-dependent changes in the redox state of PQ may universally trigger cellular responses to stressors that affect membrane properties.

Influence of membrane fatty acid composition and fluidity on airborne survival of Escherichia coli.

PubMed

Ng, Tsz Wai; Chan, Wing Lam; Lai, Ka Man

2018-04-01

Finding ways to predict and control the survival of bacterial aerosols can contribute to the development of ways to alleviate a number of crucial microbiological problems. Significant damage in the membrane integrity of Escherichia coli during aerosolization and airborne suspension has been revealed which has prompted the question of how the membrane fatty acid composition and fluidity influence the survival of airborne bacteria. Two approaches of using isogenic mutants and different growth temperatures were selected to manipulate the membrane fatty acid composition of E. coli before challenging the bacteria with different relative humidity (RH) levels in an aerosol chamber. Among the mutants (fabR - , cfa. fadA - ), fabR - had the lowest membrane fluidity index (FI) and generally showed a higher survival than the parental strain. Surprisingly, its resistance to airborne stress was so strong that its viability was fully maintained even after airborne suspension at 40% RH, a harsh RH level to bacterial survival. Moreover, E. coli cultured at 20 °C with a higher FI than that at 30 and 37 °C generally had a lower survival after aerosolization and airborne suspension. Unlike FI, individual fatty acid and cyclopropane fatty acid composition did not relate to the bacterial survival. Lipid peroxidation of the membrane was undetected in all the bacteria. Membrane fluidity plays a stronger role in determining the bacteria survival during airborne suspension than during aerosolization. Certain relationships between FI and bacteria survival were identified, which could help predict the transmission of bacteria under different conditions.

Religion and Sexual Identity Fluidity in a National Three-Wave Panel of U.S. Adults.

PubMed

Scheitle, Christopher P; Wolf, Julia Kay

2018-05-01

Research has shown that cross-sectional estimates of sexual identities overlook fluidity in those identities. Research has also shown that social factors, such as competing identities, can influence sexual identity fluidity. We contributed to this literature in two ways. First, we utilized a representative panel of US adults (N = 1034) surveyed in 2010, 2012, and 2014 by the General Social Survey. The addition of a third observation allowed us to examine more complexity in sexual identity fluidity. We found that 2.40% of US adults reported at least one change in sexual identity across the 4 years, with 1.59% reporting one change and 0.81% reporting two changes. Our second contribution came from examining the role of religion, as past research has suggested that religion can destabilize and prolong sexual identity development. We found that lesbian or gay individuals (N = 17), bisexuals (N = 15), and females (N = 585) showed more sexual identity fluidity compared to heterosexuals (N = 1003) and males (N = 450), respectively. Marital status, age, race, and education did not have significant associations with sexual identity fluidity. Regarding the role of religion, we found that participants identifying as more religious in Wave 1 showed more fluidity in sexual identity across later observations. Further analysis showed that higher levels of religiosity make it more likely that lesbian or gay individuals will be fluid in sexual identity, but this is not the case for heterosexual individuals. This finding reinforces past qualitative research that has suggested that religion can extend or complicate sexual minorities' identity development.

No evidence for homeoviscous adaptation in intertidal snails: analysis of membrane fluidity during thermal acclimation, thermal acclimatization, and across thermal microhabitats.

PubMed

Rais, Amber; Miller, Nathan; Stillman, Jonathon H

2010-01-01

Many eurythermal organisms alter composition of their membranes to counter perturbing effects of environmental temperature variation on membrane fluidity, a process known as homeoviscous adaptation. Marine intertidal gastropods experience uniquely large thermal excursions that challenge the functional integrity of their membranes on tidal and seasonal timescales. This study measured and compared membrane fluidity in marine intertidal snail species under three scenarios: (1) laboratory thermal acclimation, (2) thermal acclimatization during a hot midday low tide, and (3) thermal acclimatization across the vertical intertidal zone gradient in temperature. For each scenario, we used fluorescence polarization of the membrane probe DPH to measure membrane fluidity in individual samples of gill and mantle tissue. A four-week thermal acclimation of Tegula funebralis to 5, 15, and 25°C did not induce differences in membrane fluidity. Littorina keenae sampled from two thermal microhabitats at the beginning and end of a hot midday low tide exhibited no significant differences in membrane fluidity, either as a function of time of day or as a function of thermal microhabitat, despite changes in body temperature up to 24°C within 8 h. Membrane fluidities of a diverse group of snails collected from high, middle, and low vertical regions of the intertidal zone varied among species but did not correlate with thermal microhabitat. Our data suggest intertidal gastropod snails do not exhibit homeoviscous adaptation of gill and mantle membranes. We discuss possible alternatives for how these organisms counter thermal excursions characteristic of the marine intertidal zone.

Influence of zinc deficiency on cell-membrane fluidity in Jurkat, 3T3 and IMR-32 cells.

PubMed Central

Verstraeten, Sandra V; Zago, M Paola; MacKenzie, Gerardo G; Keen, Carl L; Oteiza, Patricia I

2004-01-01

We investigated whether zinc deficiency can affect plasma membrane rheology. Three cell lines, human leukaemia T-cells (Jurkat), rat fibroblasts (3T3) and human neuroblastoma cells (IMR-32), were cultured for 48 h in control medium, in zinc-deficient medium (1.5 microM zinc; 1.5 Zn), or in the zinc-deficient medium supplemented with 15 microM zinc (15 Zn). The number of viable cells was lower in the 1.5 Zn group than in the control and 15 Zn groups. The frequency of apoptosis was higher in the 1.5 Zn group than in the control and 15 Zn groups. Membrane fluidity was evaluated using the 6-(9-anthroyloxy)stearic acid and 16-(9-anthroyloxy)palmitic acid probes. Membrane fluidity was higher in 1.5 Zn cells than in the control cells; no differences were observed between control cells and 15 Zn cells. The effect of zinc deficiency on membrane fluidity at the water/lipid interface was associated with a higher phosphatidylserine externalization. The higher membrane fluidity in the hydrophobic region of the bilayer was correlated with a lower content of arachidonic acid. We suggest that the increased fluidity of the membrane secondary to zinc deficiency is in part due to a decrease in arachidonic acid content and the apoptosis-related changes in phosphatidylserine distribution. PMID:14629198

Differences in Sexual Orientation Diversity and Sexual Fluidity in Attractions Among Gender Minority Adults in Massachusetts.

PubMed

Katz-Wise, Sabra L; Reisner, Sari L; Hughto, Jaclyn White; Keo-Meier, Colton L

2016-01-01

This study characterized sexual orientation identities and sexual fluidity in attractions in a community-based sample of self-identified transgender and gender-nonconforming adults in Massachusetts. Participants were recruited in 2013 using bimodel methods (online and in person) to complete a one-time, Web-based quantitative survey that included questions about sexual orientation identity and sexual fluidity. Multivariable logistic regression models estimated adjusted risk ratios (aRRs) and 95% confidence intervals (95% CIs) to examine the correlates of self-reported changes in attractions ever in lifetime among the whole sample (n = 452) and after transition among those who reported social gender transition (n = 205). The sample endorsed diverse sexual orientation identities: 42.7% queer, 19.0% other nonbinary, 15.7% bisexual, 12.2% straight, and 10.4% gay/lesbian. Overall, 58.2% reported having experienced changes in sexual attractions in their lifetime. In adjusted models, trans masculine individuals were more likely than trans feminine individuals to report sexual fluidity in their lifetime (aRR = 1.69; 95% CI = 1.34, 2.12). Among those who transitioned, 64.6% reported a change in attractions posttransition, and trans masculine individuals were less likely than trans feminine individuals to report sexual fluidity (aRR = 0.44; 95% CI = 0.28, 0.69). Heterogeneity of sexual orientation identities and sexual fluidity in attractions are the norm rather than the exception among gender minority people.

Fluidity models in ancient Greece and current practices of sex assignment

PubMed Central

Chen, Min-Jye; McCann-Crosby, Bonnie; Gunn, Sheila; Georgiadis, Paraskevi; Placencia, Frank; Mann, David; Axelrad, Marni; Karaviti, L.P; McCullough, Laurence B.

2018-01-01

Disorders of sexual differentiation such as androgen insensitivity and gonadal dysgenesis can involve an intrinsic fluidity at different levels, from the anatomical and biological to the social (gender) that must be considered in the context of social constraints. Sex assignment models based on George Engel’s biopsychosocial aspects model of biology accept fluidity of gender as a central concept and therefore help establish expectations within the uncertainty of sex assignment and anticipate potential changes. The biology underlying the fluidity inherent to these disorders should be presented to parents at diagnosis, an approach that the gender medicine field should embrace as good practice. Greek mythology provides many accepted archetypes of change, and the ancient Greek appreciation of metamorphosis can be used as context with these patients. Our goal is to inform expertise and optimal approaches, knowing that this fluidity may eventually necessitate sex reassignment. Physicians should provide sex assignment education based on different components of sexual differentiation, prepare parents for future hormone-triggered changes in their children, and establish a sex-assignment algorithm. PMID:28478088

Membrane Fluidity Sensing on the Single Virus Particle Level with Plasmonic Nanoparticle Transducers.

PubMed

Feizpour, Amin; Stelter, David; Wong, Crystal; Akiyama, Hisashi; Gummuluru, Suryaram; Keyes, Tom; Reinhard, Björn M

2017-10-27

Viral membranes are nanomaterials whose fluidity depends on their composition, in particular, the cholesterol (chol) content. As differences in the membrane composition of individual virus particles can lead to different intracellular fates, biophysical tools capable of sensing the membrane fluidity on the single-virus level are required. In this manuscript, we demonstrate that fluctuations in the polarization of light scattered off gold or silver nanoparticle (NP)-labeled virus-like-particles (VLPs) encode information about the membrane fluidity of individual VLPs. We developed plasmonic polarization fluctuation tracking microscopy (PFTM) which facilitated the investigation of the effect of chol content on the membrane fluidity and its dependence on temperature, for the first time on the single-VLP level. Chol extraction studies with different methyl-β-cyclodextrin (MβCD) concentrations yielded a gradual decrease in polarization fluctuations as a function of time. The rate of chol extraction for individual VLPs showed a broad spread, presumably due to differences in the membrane composition for the individual VLPs, and this heterogeneity increased with decreasing MβCD concentration.

Fluidity models in ancient Greece and current practices of sex assignment.

PubMed

Chen, Min-Jye; McCann-Crosby, Bonnie; Gunn, Sheila; Georgiadis, Paraskevi; Placencia, Frank; Mann, David; Axelrad, Marni; Karaviti, L P; McCullough, Laurence B

2017-06-01

Disorders of sexual differentiation such as androgen insensitivity and gonadal dysgenesis can involve an intrinsic fluidity at different levels, from the anatomical and biological to the social (gender) that must be considered in the context of social constraints. Sex assignment models based on George Engel's biopsychosocial aspects model of biology accept fluidity of gender as a central concept and therefore help establish expectations within the uncertainty of sex assignment and anticipate potential changes. The biology underlying the fluidity inherent to these disorders should be presented to parents at diagnosis, an approach that the gender medicine field should embrace as good practice. Greek mythology provides many accepted archetypes of change, and the ancient Greek appreciation of metamorphosis can be used as context with these patients. Our goal is to inform expertise and optimal approaches, knowing that this fluidity may eventually necessitate sex reassignment. Physicians should provide sex assignment education based on different components of sexual differentiation, prepare parents for future hormone-triggered changes in their children, and establish a sex-assignment algorithm. Copyright © 2017 Elsevier Inc. All rights reserved.

The lipid content of cisplatin- and doxorubicin-resistant MCF-7 human breast cancer cells.

PubMed

Todor, I N; Lukyanova, N Yu; Chekhun, V F

2012-07-01

To perform the comparative study both of qualitative and quantitative content of lipids in parental and drug resistant breast cancer cells. Parental (MCF-7/S) and resistant to cisplatin (MCF-7/CP) and doxorubicin (MCF-7/Dox) human breast cancer cells were used in the study. Cholesterol, total lipids and phospholipids content were determined by means of thin-layer chromatography. It was found that cholesterol as well as cholesterol ethers content are significantly higher but diacylglycerols, triacyl-glycerols content are significantly lower in resistant cell strains than in parental (sensitive) cells. Moreover the analysis of individual phospholipids showed the increase of sphingomyelin, phosphatidylserine, cardiolipin, phosphatidic acid and the decrease of phosphatidy-lethanolamine, phosphatidylcholine in MCF-7/CP and MCF-7/Dox cells. Obtained results allow to suggest that the lipid profile changes can mediate the modulation of membrane fluidity in drug resistant MCF-7 breast cancer cells.

ATP-induced lipid membrane reordering in the myelinated nerve fiber identified using Raman spectroscopy

NASA Astrophysics Data System (ADS)

Kutuzov, N. P.; Brazhe, A. R.; Yusipovich, A. I.; Maksimov, G. V.; Dracheva, O. E.; Lyaskovskiy, V. L.; Bulygin, F. V.; Rubin, A. B.

2013-07-01

We demonstrate a successful application of Raman spectroscopy to the problem of lipid ordering with microscopic resolution in different regions of the myelinated nerve fiber. Simultaneous collection of Raman spectra of lipids and carotenoids has enabled us to characterize membrane fluidity and the degree of lipid ordering based on intensity ratios for the 1527/1160 and 2940/2885 cm-1 bands. We show that the intensity profiles of the major Raman bands vary significantly between the three major regions of myelinated nerve fiber: internode, paranode and the node of Ranvier. Mapping Raman peak intensities over these areas suggested that the carotenoid molecules are localized in the myelin membranes of nerve cells. Paranodal membranes were sensitive to extracellular ATP. ATP solutions (7 mM) influenced the 1527/1160 and 2940/2885 cm-1 intensity ratios. Changes in both carotenoid and lipid Raman spectra were in accord and indicated an increase in lipid ordering degree and decrease in membrane fluidity under ATP administration. The collected data provide evidence for the existence of a regulatory purinergic signaling pathway in the peripheral nervous system.

Electron paramagnetic resonance investigation on modulatory effect of benidipine on membrane fluidity of erythrocytes in essential hypertension.

PubMed

Tsuda, Kazushi

2008-03-01

It has been shown that benidipine, a long-lasting calcium (Ca) channel blocker, may exert its protective effect against vascular disorders by increasing nitric oxide (NO) production. The purpose of the present study was to investigate whether orally administered benidipine might influence the membrane function in patients with essential hypertension. We measured the membrane fluidity of erythrocytes by using an electron paramagnetic resonance (EPR) and spin-labeling method. In the preliminary study using erythrocytes obtained from healthy volunteers, benidipine decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS in the EPR spectra in vitro. The finding indicated that benidipine increased the membrane fluidity and improved the microviscosity of erythrocytes. In addition, it was demonstrated that the effect of benidipine on membrane fluidity of erythrocytes was significantly potentiated by the NO-substrate, L-arginine. In the separate series of the study, we observed that orally administered benidipine for 4 weeks significantly increased the membrane fluidity of erythrocytes with a concomitant increase in plasma NO metabolite levels in hypertensive subjects. The results of the present study demonstrated that benidipine might increase the membrane fluidity and improve the microviscosity of erythrocytes both in vitro and in vivo, to some extent, by the NO-dependent mechanism. Furthermore, it is strongly suggested that orally administered benidipine might have a beneficial effect on the rheologic behavior of erythrocytes and the improvement of the microcirculation in hypertensive subjects.

Differences in Sexual Orientation Diversity and Sexual Fluidity in Attractions among Gender Minority Adults in Massachusetts

PubMed Central

Katz-Wise, Sabra L.; Reisner, Sari L.; White, Jaclyn M.; Keo-Meier, Colton L.

2015-01-01

This study characterized sexual orientation identities and sexual fluidity in attractions in a community-based sample of self-identified transgender and gender nonconforming adults in Massachusetts. Participants were recruited in 2013 using bi-model methods (online and in-person) to complete a one-time web-based quantitative survey that included questions about sexual orientation identity and sexual fluidity. Multivariable logistic regression models estimated Adjusted Risk Ratios (aRR) and 95% Confidence Intervals (95% CI) to examine the correlates of self-reported changes in attractions ever in lifetime among the whole sample (n=452) and after transition among those who reported social gender transition (n=205). The sample endorsed diverse sexual orientation identities: 42.7% queer, 19.0% other non-binary, 15.7% bisexual, 12.2% straight, 10.4% gay/lesbian. Overall, 58.2% reported having experienced changes in sexual attractions in their lifetime. In adjusted models, trans masculine individuals were more likely than trans feminine individuals to report sexual fluidity in their lifetime (aRR=1.69; 95% CI=1.34, 2.12). Among those who transitioned, 64.6% reported a change in attractions post-transition and trans masculine individuals were less likely than trans feminine individuals to report sexual fluidity (aRR=0.44; 95% CI=0.28, 0.69). Heterogeneity of sexual orientation identities and sexual fluidity in attractions are the norm rather than the exception among gender minority people. PMID:26156113

Shear viscosity and imperfect fluidity in bosonic and fermionic superfluids

NASA Astrophysics Data System (ADS)

Boyack, Rufus; Guo, Hao; Levin, K.

2014-12-01

In this paper we address the ratio of the shear viscosity to entropy density η /s in bosonic and fermionic superfluids. A small η /s is associated with nearly perfect fluidity, and more general measures of the fluidity perfection/imperfection are of wide interest to a number of communities. We use a Kubo approach to concretely address this ratio via low-temperature transport associated with the quasiparticles. Our analysis for bosonic superfluids utilizes the framework of the one-loop Bogoliubov approximation, whereas for fermionic superfluids we apply BCS theory and its BCS-BEC extension. Interestingly, we find that the transport properties of strict BCS and Bogoliubov superfluids have very similar structures, albeit with different quasiparticle dispersion relations. While there is a dramatic contrast between the power law and exponential temperature dependence for η alone, the ratio η /s for both systems is more similar. Specifically, we find the same linear dependence (on the ratio of temperature T to inverse lifetime γ (T ) ) with η /s ∝T /γ (T ) , corresponding to imperfect fluidity. By contrast, near the unitary limit of BCS-BEC superfluids a very different behavior results, which is more consistent with near-perfect fluidity.

Fluid movement and fluid social cognition: bodily movement influences essentialist thought.

PubMed

Slepian, Michael L; Weisbuch, Max; Pauker, Kristin; Bastian, Brock; Ambady, Nalini

2014-01-01

Rigid social categorization can lead to negative social consequences such as stereotyping and prejudice. The authors hypothesized that bodily experiences of fluidity would promote fluidity in social-categorical thinking. Across a series of experiments, fluid movements compared with nonfluid movements led to more fluid lay theories of social categories, more fluidity in social categorization, and consequences of fluid social-categorical thinking, decreased stereotype endorsement, and increased concern for social inequalities. The role of sensorimotor states in fluid social cognition, with consequences for social judgment and behavior, is discussed.

Microscale mechanical characterization of materials for extreme environments

NASA Astrophysics Data System (ADS)

Ozerinc, Sezer

Nanocrystalline metals are promising materials for applications that require outstanding strength and stability in extreme environments. Further improvements in the desirable mechanical properties of these materials require a better understanding of the relationship between their microstructure and grain boundary deformation behavior. Previous molecular dynamics simulations suggested that solute additions to grain boundaries can enhance the strength of nanocrystalline metals, but there has been a lack of experimental studies investigating this prediction. This dissertation presents mechanical and microstructural characterization of nanocrystalline Cu alloys and demonstrate that addition of Nb solutes to grain boundaries greatly enhances the strength of Cu. The measured hardness of Cu90Nb10 alloy is 5.6 GPa which is more than double the hardness of nanocrystalline pure Cu. Microstructural characterization through transmission electron microscopy and energy-dispersive X-ray spectroscopy on these alloys indicates a strong correlation between the grain boundary composition and the hardness. Variation of measured hardness with measured grain boundary composition is in very good agreement with previous molecular dynamics simulation predictions. The results of this work provide experimental evidence that grain boundary doping enhances the strength of nanocrystalline Cu far beyond that predicted by classical Hall-Petch strengthening and decreasing grain boundary energy through solute additions is the key to reaching theoretical strength in nanocrystalline metals. Irradiation induced creep is a deformation mechanism that takes place under combined stress and particle bombardment. Effective characterization of this phenomenon on nanostructured materials is crucial for the assessment of their potential use in next generation nuclear power plants. Direct measurements of irradiation induced creep under MeV-heavy ion bombardment have not been feasible until recently due to the requirements of micron-sized specimens, muN-level force sensitivity, and nm-level displacement sensitivity. A recently developed mechanical characterization technique, micropillar compression, has enabled the testing of miniaturized specimens; however, there has been no demonstration of the application of this technique to irradiation induced creep measurements. This dissertation presents the development of an in situ measurement apparatus for compression testing of micron-sized cylindrical specimens under MeV-heavy ion bombardment. The apparatus has a force resolution of 1 muN and a displacement resolution of 1 nm. The apparatus measured irradiation induced creep in four different amorphous materials and the findings clarified the significance of different creep mechanisms in these materials. In amorphous metals and amorphous Si, the measured irradiation induced fluidity is ≈ 3 dpa-1GPa-1 (dpa: displacements per atom). The measured fluidity is in excellent agreement with previous molecular dynamics simulation predictions, providing experimental evidence for point defect mediated plastic flow under ion bombardment. For amorphous SiO2, stress relaxation through thermal spikes further contribute to the creep response, resulting in higher fluidities up to ≈ 83 dpa-1GPa -1. Finally, this dissertation presents the further development of the creep testing apparatus for high temperature measurements. The apparatus demonstrated good thermal and mechanical stability and measured irradiation induced creep of nanocrystalline Cu at 200°C. Resulting irradiation induced fluidity is ≈ 10% of the fluidity of the amorphous metals, in agreement with previous measurements on free-standing films. Understanding the creep behavior of nanostructured metals under heavy ion bombardment at elevated temperatures is important for identifying the governing creep mechanisms in these materials. The developed apparatus provides a new and effective method of accelerated mechanical characterization of such promising materials for their potential use in future nuclear applications.

Rice mutants deficient in ω-3 fatty acid desaturase (FAD8) fail to acclimate to cold temperatures.

PubMed

Tovuu, Altanzaya; Zulfugarov, Ismayil S; Wu, Guangxi; Kang, In Soon; Kim, Choongrak; Moon, Byoung Yong; An, Gynheung; Lee, Choon-Hwan

2016-12-01

To investigate the role of ω-3 fatty acid (FA) desaturase (FAD8) during cold acclimation in higher plants, we characterized three independent T-DNA insertional knock-out mutants of OsFAD8 from rice (Oryza sativa L.). At room temperature (28 °C), osfad8 plants exhibited significant alterations in fatty acid (FA) unsaturation for all four investigated plastidic lipid classes. During a 5-d acclimation period at 4 °C, further changes in FA unsaturation in both wild-type (WT) and mutant plants varied according to the type of lipid. We also monitored the fluidity of the thylakoid membrane using a threshold temperature to represent the change in fluorescence. The values were altered significantly by both FAD8 mutation and cold acclimation, suggesting that factors other than FAD8 are involved in C18 FA unsaturation and fluctuations in membrane fluidity. Similarly, significant changes were noted for both the mutant and WT samples in terms of their FA compositions as well as activities related to photosystem (PS) I, PSII, and photoprotection. This included the development of non-photochemical quenching and increased zeaxanthin accumulation. Despite the relatively small changes in FA composition during cold acclimation, cold-inducible FAD8 knock-out mutants displayed strong differences in photoprotective activities and a further drop in membrane fluidity. The mutants were more sensitive than WT to short-term low-temperature stress that resulted in increased production of reactive oxygen species after 5 d of chilling. Taken together, our findings suggest that FA unsaturation by OsFAD8 is crucial for the acclimation of higher plants to low-temperature stress. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Estriol improves membrane fluidity of erythrocytes by the nitric oxide-dependent mechanism: an electron paramagnetic resonance study.

PubMed

Tsuda, K; Shimamoto, Y; Kimura, K; Nishio, I; Masuyama, Y

2001-05-01

The present in vitro study was performed to investigate the effects of estriol (E3) on membrane fluidity of erythrocytes by means of an electron paramagnetic resonance (EPR) and spin-labeling method. E3 was shown to significantly decrease the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-NS obtained from EPR spectra of erythrocyte membranes. This finding indicated that E3 might increase the membrane fluidity of erythrocytes. The effect of E3 was significantly potentiated by the nitric oxide (NO) donor, S-nitroso-N-acetylpenicillamine (SNAP), and a cyclic guanosine 3',5'-monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change in the membrane fluidity induced by E3 was antagonized by the NO synthase inhibitor, L-NG-nitroarginine-methyl-ester (L-NAME), and asymmetric dimethyl-L-arginine (ADMA). The results of the present study showed that E3 significantly increased the membrane fluidity and improved the microviscosity of erythrocyte membranes, partially mediated by an NO- and cGMP-dependent pathway. Furthermore, the data might be consistent with the hypothesis that E3 could have a beneficial effect on the rheological behavior of erythrocytes and may play a crucial role in the regulation of microcirculation.

Fluidization of Membrane Lipids Enhances the Tolerance of Saccharomyces cerevisiae to Freezing and Salt Stress▿

PubMed Central

Rodríguez-Vargas, Sonia; Sánchez-García, Alicia; Martínez-Rivas, Jose Manuel; Prieto, Jose Antonio; Randez-Gil, Francisca

2007-01-01

Unsaturated fatty acids play an essential role in the biophysical characteristics of cell membranes and determine the proper function of membrane-attached proteins. Thus, the ability of cells to alter the degree of unsaturation in their membranes is an important factor in cellular acclimatization to environmental conditions. Many eukaryotic organisms can synthesize dienoic fatty acids, but Saccharomyces cerevisiae can introduce only a single double bond at the Δ9 position. We expressed two sunflower (Helianthus annuus) oleate Δ12 desaturases encoded by FAD2-1 and FAD2-3 in yeast cells of the wild-type W303-1A strain (trp1) and analyzed their effects on growth and stress tolerance. Production of the heterologous desaturases increased the content of dienoic fatty acids, especially 18:2Δ9,12, the unsaturation index, and the fluidity of the yeast membrane. The total fatty acid content remained constant, and the level of monounsaturated fatty acids decreased. Growth at 15°C was reduced in the FAD2 strains, probably due to tryptophan auxotrophy, since the trp1 (TRP1) transformants that produced the sunflower desaturases grew as well as the control strain did. Our results suggest that changes in the fluidity of the lipid bilayer affect tryptophan uptake and/or the correct targeting of tryptophan transporters. The expression of the sunflower desaturases, in either Trp+ or Trp− strains, increased NaCl tolerance. Production of dienoic fatty acids increased the tolerance to freezing of wild-type cells preincubated at 30°C or 15°C. Thus, membrane fluidity is an essential determinant of stress resistance in S. cerevisiae, and engineering of membrane lipids has the potential to be a useful tool of increasing the tolerance to freezing in industrial strains. PMID:17071783

The actin homologue MreB organizes the bacterial cell membrane

PubMed Central

Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W.

2014-01-01

The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes. PMID:24603761

The actin homologue MreB organizes the bacterial cell membrane.

PubMed

Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W

2014-03-07

The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes.

Structural Degradation and Swelling of Lipid Bilayer under the Action of Benzene.

PubMed

Odinokov, Alexey; Ostroumov, Denis

2015-12-03

Benzene and other nonpolar organic solvents can accumulate in the lipid bilayer of cellular membranes. Their effect on the membrane structure and fluidity determines their toxic properties and antibiotic action of the organic solvents on the bacteria. We performed molecular dynamics simulations of the interaction of benzene with the dimyristoylphosphatidylcholine (DMPC) bilayer. An increase in the membrane surface area and fluidity was clearly detected. Changes in the acyl chain ordering, tilt angle, and overall bilayer thickness were, however, much less marked. The dependence of all computed quantities on the benzene content showed two regimes separated by the solubility limit of benzene in water. When the amount of benzene exceeded this point, a layer of almost pure benzene started to grow between the membrane leaflets. This process corresponds to the nucleation of a new phase and provides a molecular mechanism for the mechanical rupture of the bilayer under the action of nonpolar compounds.

Nitric oxide improves membrane fluidity of erythrocytes in essential hypertension: An electron paramagnetic resonance investigation.

PubMed

Tsuda, K; Kimura, K; Nishio, I; Masuyama, Y

2000-09-07

It has been shown that rheological abnormality might be an etiological factor in hypertension. Recent studies have revealed that human erythrocytes possess a nitric oxide (NO) synthase and that this activation might be involved in the regulation of rheological properties of erythrocytes. The present study was undertaken to investigate the role of NO in the regulation of membrane functions of erythrocytes in patients with essential hypertension by means of an electron paramagnetic resonance (EPR) and spin-labeling method. The NO donor S-nitroso-N-acetylpenicillamine (SNAP) decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(0)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner. The finding indicated that the NO donor increased the membrane fluidity of erythrocytes. In addition, the effect of SNAP was significantly potentiated by 8-bromo-cyclic guanosine monophosphate. By contrast, the change of the fluidity induced by SNAP was reversed in the presence of L-N(G)-nitroarginine methyl ester and asymmetric dimethyl L-arginine. In patients with essential hypertension, the membrane fluidity of erythrocytes was significantly lower than in the normotensive subjects. The effect of SNAP was more pronounced in essential hypertension than in normotensive subjects. These results showed that NO increased the membrane fluidity and decreased the rigidity of cell membranes. Furthermore, the greater effect of NO on the fluidity in essential hypertension suggests that NO might actively participate in the regulation of rheological behavior of erythrocytes and have a crucial role in the improvement of microcirculation in hypertension. Copyright 2000 Academic Press.

Fractography, fluidity, and tensile properties of aluminum/hematite particulate composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, S.C.; Girish, B.M.; Kamath, R.

1999-06-01

This paper examines the effect of hematite (iron oxide) particles on the fluidity of the molten composite as well as the tensile properties and fracture behavior of the solidified as-cast aluminum composites. The percentage of hematite in the composite was varied from 1 to 7% in steps of 2% by weight. The vortex method was employed to prepare the composites. It followed from the results obtained that the ultimate tensile strength and Young`s modulus of the composite increased while the liquid fluidity and solid ductility decreased with the increase in hematite content in the composite specimens. The fluidity of themore » liquid was greater in a metal mold than in a sand mold, and it decreased with an increase in reinforcing particle size and increased with pouring temperature. The presence of the reinforcing particles altered the fracture behavior of the solid composites considerably. Final fracture of the composite occurred due to the propagation of cracks through the matrix between the reinforcing particles.« less

Multiscale Modelling of the 2011 Tohoku Tsunami with Fluidity: Coastal Inundation and Run-up.

NASA Astrophysics Data System (ADS)

Hill, J.; Martin-Short, R.; Piggott, M. D.; Candy, A. S.

2014-12-01

Tsunami-induced flooding represents one of the most dangerous natural hazards to coastal communities around the world, as exemplified by Tohoku tsunami of March 2011. In order to further understand this hazard and to design appropriate mitigation it is necessary to develop versatile, accurate software capable of simulating large scale tsunami propagation and interaction with coastal geomorphology on a local scale. One such software package is Fluidity, an open source, finite element, multiscale, code that is capable of solving the fully three dimensional Navier-Stokes equations on unstructured meshes. Such meshes are significantly better at representing complex coastline shapes than structured meshes and have the advantage of allowing variation in element size across a domain. Furthermore, Fluidity incorporates a novel wetting and drying algorithm, which enables accurate, efficient simulation of tsunami run-up over complex, multiscale, topography. Fluidity has previously been demonstrated to accurately simulate the 2011 Tohoku tsunami (Oishi et al 2013) , but its wetting and drying facility has not yet been tested on a geographical scale. This study makes use of Fluidity to simulate the 2011 Tohoku tsunami and its interaction with Japan's eastern shoreline, including coastal flooding. The results are validated against observations made by survey teams, aerial photographs and previous modelling efforts in order to evaluate Fluidity's current capabilities and suggest methods of future improvement. The code is shown to perform well at simulating flooding along the topographically complex Tohoku coast of Japan, with major deviations between model and observation arising mainly due to limitations imposed by bathymetry resolution, which could be improved in future. In theory, Fluidity is capable of full multiscale tsunami modelling, thus enabling researchers to understand both wave propagation across ocean basins and flooding of coastal landscapes down to interaction with individual defence structures. This makes the code an exciting candidate for use in future studies aiming to investigate tsunami risk elsewhere in the world. Oishi, Y. et al. Three-dimensional tsunami propagation simulations using an unstructured mesh finite element model. J. Geophys. Res. [Solid Earth] 118, 2998-3018 (2013).

Investigation of the fluidity of biological fluids with a PDDTBN spin probe

NASA Astrophysics Data System (ADS)

Severcan, Feride; Acar, Berrin; Gökalp, Saadet

1997-06-01

The aim of this study is to ascertain whether the electron spin resonance technique using perdeutero-di- t-butyl nitroxide (PDDTBN) as a spin probe is able to monitor relative fluidity changes occurring in body fluids, such as blood and parotid saliva, according to different physiological conditions. The present study reveals that the spin probe PDDTBN is able to monitor the fluidity changes in parotid saliva related to habitual smoking, and in whole blood related to the estradiol level. The rotational correlation time of the spin probe and the local viscosity values of the parotid saliva and blood have been reported.

A role for protein kinase C in the regulation of membrane fluidity and Ca²(+) flux at the endoplasmic reticulum and plasma membranes of HEK293 and Jurkat cells.

PubMed

Chen, Lihong; Meng, Qingli; Jing, Xian; Xu, Pingxiang; Luo, Dali

2011-02-01

Protein kinase C (PKC) plays a prominent role in the regulation of a variety of cellular functions, including Ca²(+) signalling. In HEK293 and Jurkat cells, the Ca²(+) release and Ca²(+) uptake stimulated by several different activators were attenuated by activation of PKC with phorbol myristate acetate (PMA) or 1-oleoyl-2-acetyl-sn-glycerol (OAG) and potentiated by PKC inhibition with Gö6983 or knockdown of PKCα or PKCβ using shRNA. Immunostaining and Western blotting analyses revealed that PKCα and PKCβII accumulated at the plasma membrane (PM) and that these isoforms, along with PKCβI, also translocated to the endoplasmic reticulum (ER) upon activation with PMA. Measurements of membrane fluidity showed that, like the cell membrane stabilizers bovine serum albumin (BSA) and ursodeoxycholate (UDCA), PMA and OAG significantly reduced the fluidity of both the PM and ER membranes; these effects were blocked in PKC-knockdown cells. Interestingly, both BSA and UDCA inhibited the Ca²(+) responses to agonists to the same extent as PMA, whereas Tween 20, which increases membrane fluidity, raised the internal Ca²(+) concentration. Thus, activation of PKC induces both translocation of PKC to the PM and ER membranes and downregulation of membrane fluidity, thereby negatively modulating Ca²(+) flux. Copyright © 2010 Elsevier Inc. All rights reserved.

Application of the compensated Arrhenius formalism to fluidity data of polar organic liquids.

PubMed

Petrowsky, Matt; Fleshman, Allison M; Frech, Roger

2013-03-14

The temperature dependence of viscosity (the reciprocal of fluidity) in polar liquids has been studied for over a century, but the available theoretical models have serious limitations. Consequently, the viscosity is often described with empirical equations using adjustable fitting parameters that offer no insight into the molecular mechanism of transport. We have previously reported a novel approach called the compensated Arrhenius formalism (CAF) to describe ionic conductivity, self-diffusion, and dielectric relaxation in terms of molecular and system properties. Here the CAF is applied to fluidity data of pure n-acetates, 2-ketones, n-nitriles, and n-alcohols over the temperature range 5-85 °C. The fluidity is represented as an Arrhenius-like expression that includes a static dielectric constant dependence in the exponential prefactor. The dielectric constant dependence results from the dependence of mass and charge transport on the molecular dipole moment and the solvent dipole density. The CAF is the only self-consistent description of fluid transport in polar liquids written solely in terms of molecular and system parameters. A scaling procedure is used to calculate the activation energy for transport. We find that the activation energies for fluidity of the aprotic liquids are comparable in value, whereas a higher average E(a) value is observed for the n-alcohol data. Finally, we contrast the molecular description of transport presented here with the conventional hydrodynamic model.

Effects of unripe Citrus hassaku fruits extract and its flavanone glycosides on blood fluidity.

PubMed

Itoh, Kimihisa; Masuda, Megumi; Naruto, Shunsuke; Murata, Kazuya; Matsuda, Hideaki

2010-01-01

The enhancement of blood fluidity may lead to improvements in skin problems resulting from unsmooth circulation or blood stagnation. Since a 50% ethanolic extract (CH-ext) obtained from unripe Citrus hassaku fruits may be a useful ingredient in skin-whitening cosmetics, the present study was designed to examine the effect of CH-ext on blood fluidity. CH-ext concentration-dependently inhibited in vitro collagen-induced rabbit platelet aggregation and in vitro polybrene-induced rat erythrocyte aggregation. The CH-ext showed in vitro fibrinolysis activity in fibrin plate assay. Activity-guided fractionation of the CH-ext using antiplatelet activity, inhibitory activity of erythrocyte aggregation, and fibrinolysis activity revealed that these activities of CH-ext were attributable to naringenin-7-glycoside (prunin). Successive oral administration of CH-ext to rats inhibited the lipopolysaccharide (LPS)-induced decrease of blood platelets and fibrinogen, and LPS-induced increase of fibrin degradation products (FDP) in LPS-induced disseminated intravascular coagulation (DIC) model rats. Effects of CH-ext on blood fluidity were analyzed by a micro channel array flow analyzer (MC-FAN). Preventive oral administration of CH-ext to rats showed dose-dependent reduction of the passage time of whole blood flow of the DIC model rats in comparison with that of the vehicle control rats. These results imply that CH-ext may have effects which improve effects on blood fluidity.

Born both ways: the alloparenting hypothesis for sexual fluidity in women.

PubMed

Kuhle, Barry X; Radtke, Sarah

2013-04-07

Given the primacy of reproduction, same-sex sexual behavior poses an evolutionary puzzle. Why would selection fashion motivational mechanisms to engage in sexual behaviors with members of the same sex? We propose the alloparenting hypothesis, which posits that sexual fluidity in women is a contingent adaptation that increased ancestral women's ability to form pair bonds with female alloparents who helped them rear children to reproductive age. Ancestral women recurrently faced the adaptive problems of securing resources and care for their offspring, but were frequently confronted with either a dearth of paternal resources due to their mates' death, an absence of paternal investment due to rape, or a divestment of paternal resources due to their mates' extra-pair mating efforts. A fluid sexuality would have helped ancestral women secure resources and care for their offspring by promoting the acquisition of allomothering investment from unrelated women. Under this view, most heterosexual women are born with the capacity to form romantic bonds with both sexes. Sexual fluidity is a conditional reproductive strategy with pursuit of men as the default strategy and same-sex sexual responsiveness triggered when inadequate paternal investment occurs or when women with alloparenting capabilities are encountered. Discussion focuses on (a) evidence for alloparenting and sexual fluidity in humans and other primates; (b) alternative explanations for sexual fluidity in women; and(c) fourteen circumstances predicted to promote same-sex sexual behavior in women.

Role of Alcohols in Growth, Lipid Composition, and Membrane Fluidity of Yeasts, Bacteria, and Archaea ▿

PubMed Central

Huffer, Sarah; Clark, Melinda E.; Ning, Jonathan C.; Blanch, Harvey W.; Clark, Douglas S.

2011-01-01

Increased membrane fluidity, which causes cofactor leakage and loss of membrane potential, has long been documented as a cause for decreased cell growth during exposure to ethanol, butanol, and other alcohols. Reinforcement of the membrane with more complex lipid components is thus thought to be beneficial for the generation of more tolerant organisms. In this study, organisms with more complex membranes, namely, archaea, did not maintain high growth rates upon exposure to alcohols, indicating that more complex lipids do not necessarily fortify the membrane against the fluidizing effects of alcohols. In the presence of alcohols, shifts in lipid composition to more saturated and unbranched lipids were observed in most of the organisms tested, including archaea, yeasts, and bacteria. However, these shifts did not always result in a decrease in membrane fluidity or in greater tolerance of the organism to alcohol exposure. In general, organisms tolerating the highest concentrations of alcohols maintained membrane fluidity after alcohol exposure, whereas organisms that increased membrane rigidity were less tolerant. Altered lipid composition was a common response to alcohol exposure, with the most tolerant organisms maintaining a modestly fluid membrane. Our results demonstrate that increased membrane fluidity is not the sole cause of growth inhibition and that alcohols may also denature proteins within the membrane and cytosol, adversely affecting metabolism and decreasing cell growth. PMID:21784917

Rooster sperm plasma membrane protein and phospholipid organization and reorganization attributed to cooling and cryopreservation

USDA-ARS?s Scientific Manuscript database

Cholesterol to phospholipid ratio is used as a representation for membrane fluidity, and predictor of cryopreservation success but results are not consistent across species and ignore the impact of membrane proteins. Therefore, this research explored the modulation of membrane fluidity and protein ...

Development of laboratory test methods to replace the simulated high-temperature grout fluidity test.

DOT National Transportation Integrated Search

2014-06-01

This report contains a summary of the research performed to develop a replacement for the high-temperature grout : fluidity (HTGF) test. The HTGF test was employed in the past by FDOT to qualify post-tensioning (PT) grouts for use in : post-tensioned...

Beyond Alphabet Soup: Helping College Health Professionals Understand Sexual Fluidity

ERIC Educational Resources Information Center

Oswalt, Sara B.; Evans, Samantha; Drott, Andrea

2016-01-01

Many college students today are no longer using the terms straight, gay, lesbian, bisexual, or transgender to self-identify their sexual orientation or gender identity. This commentary explores research related to fluidity of sexual identities, emerging sexual identities used by college students, and how these identities interact with the health…

Shear viscosity to entropy density ratios and implications for (im)perfect fluidity in Fermionic and Bosonic superfluids

NASA Astrophysics Data System (ADS)

Boyack, Rufus; Guo, Hao; Levin, K.

2015-03-01

Recent experiments on both unitary Fermi gases and high temperature superconductors (arxiv:1410.4835 [cond-mat.quant-gas], arxiv:1409.5820 [cond-mat.str-el].) have led to renewed interest in near perfect fluidity in condensed matter systems. This is quantified by studying the ratio of shear viscosity to entropy density. In this talk we present calculations of this ratio in homogeneous bosonic and fermionic superfluids, with the latter ranging from BCS to BEC. While the shear viscosity exhibits a power law (for bosons) or exponential suppression (for fermions), a similar dependence is found for the respective entropy densities. As a result, strict BCS and (true) bosonic superfluids have an analogous viscosity to entropy density ratio, behaving linearly with temperature times the (T-dependent) dissipation rate; this is characteristic of imperfect fluidity in weakly coupled fluids. This is contrasted with the behavior of fermions at unitarity which we argue is a consequence of additional terms in the entropy density thereby leading to more perfect fluidity. (arXiv:1407.7572v1 [cond-mat.quant-gas])

Preparation, Characterization and Performances of Powdered Polycarboxylate Superplasticizer with Bulk Polymerization.

PubMed

Liu, Xiao; Wang, Ziming; Zheng, Yunsheng; Cui, Suping; Lan, Mingzhang; Li, Huiqun; Zhu, Jie; Liang, Xu

2014-08-29

A polycarboxylate superplasticizer (PCE) was synthesized in a non-solvent system with bulk polymerization and then was pulverized into powdered form to achieve a rapid transportation and convenient preparation. PCE synthesized by using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as a macromonomer exhibited the best fluidities and retaining properties at 80 °C and 75 °C, respectively. Besides, azobisisobutyronitrile (AIBN) was suitable as an initiator, and the fumaric acid was suitable as the third monomer. The test results of ¹H nuclear magnetic resonance (¹H NMR) confirmed the occurrences of polymerization, and the measurement results of molecular weight and distribution showed that PCE molecular weight characteristics were in accordance with their fluidity properties in cement paste. The application performances in cement showed that PCEs with the best paste fluidity retentions had the longest final setting time and the shortest setting time interval, and the PCEs with good fluidity properties can obviously delay the hydration process and lower the hydration heat. Accordingly, this is a novel, energy-saving and economical method to prepare powdered PCE in the field of concrete admixtures.

Preparation, Characterization and Performances of Powdered Polycarboxylate Superplasticizer with Bulk Polymerization

PubMed Central

Liu, Xiao; Wang, Ziming; Zheng, Yunsheng; Cui, Suping; Lan, Mingzhang; Li, Huiqun; Zhu, Jie; Liang, Xu

2014-01-01

A polycarboxylate superplasticizer (PCE) was synthesized in a non-solvent system with bulk polymerization and then was pulverized into powdered form to achieve a rapid transportation and convenient preparation. PCE synthesized by using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as a macromonomer exhibited the best fluidities and retaining properties at 80 °C and 75 °C, respectively. Besides, azobisisobutyronitrile (AIBN) was suitable as an initiator, and the fumaric acid was suitable as the third monomer. The test results of 1H nuclear magnetic resonance (1H NMR) confirmed the occurrences of polymerization, and the measurement results of molecular weight and distribution showed that PCE molecular weight characteristics were in accordance with their fluidity properties in cement paste. The application performances in cement showed that PCEs with the best paste fluidity retentions had the longest final setting time and the shortest setting time interval, and the PCEs with good fluidity properties can obviously delay the hydration process and lower the hydration heat. Accordingly, this is a novel, energy-saving and economical method to prepare powdered PCE in the field of concrete admixtures. PMID:28788184

What's Cooler Than Being Cool? Ice-Sheet Models Using a Fluidity-Based FOSLS Approach to Nonlinear-Stokes Flow

NASA Astrophysics Data System (ADS)

Allen, Jeffery M.

This research involves a few First-Order System Least Squares (FOSLS) formulations of a nonlinear-Stokes flow model for ice sheets. In Glen's flow law, a commonly used constitutive equation for ice rheology, the viscosity becomes infinite as the velocity gradients approach zero. This typically occurs near the ice surface or where there is basal sliding. The computational difficulties associated with the infinite viscosity are often overcome by an arbitrary modification of Glen's law that bounds the maximum viscosity. The FOSLS formulations developed in this thesis are designed to overcome this difficulty. The first FOSLS formulation is just the first-order representation of the standard nonlinear, full-Stokes and is known as the viscosity formulation and suffers from the problem above. To overcome the problem of infinite viscosity, two new formulation exploit the fact that the deviatoric stress, the product of viscosity and strain-rate, approaches zero as the viscosity goes to infinity. Using the deviatoric stress as the basis for a first-order system results in the the basic fluidity system. Augmenting the basic fluidity system with a curl-type equation results in the augmented fluidity system, which is more amenable to the iterative solver, Algebraic MultiGrid (AMG). A Nested Iteration (NI) Newton-FOSLS-AMG approach is used to solve the nonlinear-Stokes problems. Several test problems from the ISMIP set of benchmarks is examined to test the effectiveness of the various formulations. These test show that the viscosity based method is more expensive and less accurate. The basic fluidity system shows optimal finite-element convergence. However, there is not yet an efficient iterative solver for this type of system and this is the topic of future research. Alternatively, AMG performs better on the augmented fluidity system when using specific scaling. Unfortunately, this scaling results in reduced finite-element convergence.

Fluidity of the dietary fatty acid profile and risk of coronary heart disease and ischemic stroke: Results from the EPIC-Netherlands cohort study.

PubMed

Sluijs, I; Praagman, J; Boer, J M A; Verschuren, W M M; van der Schouw, Y T

2017-09-01

The fluidity of dietary fatty acids consumed has been suggested to inversely affect coronary heart disease (CHD) risk. Lipophilic index (LI) represents overall fluidity of the dietary fatty acid profile. Lipophilic load (LL) represents a combination of overall fluidity and absolute intake of dietary fatty acids. We investigated the relations of dietary LI and LL with risk of CHD and ischemic stroke (iStroke). We used data from the prospective EPIC-NL study, including 36,520 participants aged 20-70 years. LI and LL were calculated using dietary intake data estimated with a validated FFQ. Incident CHD (n = 2348) and iStroke (n = 479) cases were obtained through linkage to national registers during 15 years follow-up. LI and LL were not associated with CHD risk (HRs highest-versus-lowest-quartiles : 0.93 [95%CI: 0.83, 1.04], and 0.92 [95%CI: 0.79, 1.07], respectively), and neither with iStroke risk (HRs 1.15 (95%CI: 0.89, 1.48), and 0.98 (95%CI: 0.70, 1.38), respectively). Original fatty acid classes (SFA, MUFA and PUFA), and LI and LL stratified by these fatty acid classes, were overall not related to CHD and ischemic stroke either. In this Dutch population, neither the overall fluidity of the dietary fatty acid profile (LI), nor the combined fluidity and amount of fatty acids consumed (LL) were related to CHD or iStroke risk. Dietary LI and LL may have limited added value above original fatty acid classes and food sources in establishing the relation of fatty acid consumption with CVD. Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

Preparation of pH-sensitive anionic liposomes designed for drug delivery system (DDS) application.

PubMed

Aoki, Asami; Akaboshi, Hikaru; Ogura, Taku; Aikawa, Tatsuo; Kondo, Takeshi; Tobori, Norio; Yuasa, Makoto

2015-01-01

We prepared pH-sensitive anionic liposomes composed solely of anionic bilayer membrane components that were designed to promote efficient release of entrapped agents in response to acidic pH. The pH-sensitive anionic liposomes showed high dispersion stability at neutral pH, but the fluidity of the bilayer membrane was enhanced in an acidic environment. These liposomes were rather simple and were composed of dimyristoylphosphatidylcholine (DMPC), an anionic bilayer membrane component, and polyoxyethylene sorbitan monostearate (Tween 80). In particular, the present pH-sensitive anionic liposomes showed higher temporal stability than those of conventional DMPC/DPPC liposomes. We found that pHsensitive properties strongly depended on the molecular structure, pKa value, and amount of an incorporated anionic bilayer membrane component, such as sodium oleate (SO), dimyristoylphosphatidylserine (DMPS), or sodium β-sitosterol sulfate (SS). These results provide an opportunity to manipulate liposomal stability in a pH-dependent manner, which could lead to the formulation of a high performance drug delivery system (DDS).

Age Differences in Symbolic Representation: Fluidity in Representational Construction.

ERIC Educational Resources Information Center

Reifel, Stuart

This paper reports a cross-sectional, developmental study of the fluidity of children's mental functioning (representational skills) in contexts involving the representational use of blocks. Data were collected from a sample of 40 children from a laboratory school: 20 four-year-olds and 20 seven-year-olds, with an equal number of boys and girls in…

Cast B2-phase iron-aluminum alloys with improved fluidity

DOEpatents

Maziasz, Philip J.; Paris, Alan M.; Vought, Joseph D.

2002-01-01

Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

Emotion Talk in Preschool Same-Sex Friendship Groups: Fluidity over Time and Context.

ERIC Educational Resources Information Center

Kyratzis, Amy

2001-01-01

Examined "emotion talk" among 3- and 4-year-old peers in a children's center in different contexts over the academic year. Found that the boys' group evolved norms against expression of being scared with norms downgrading girl characteristics. Boys' and girls' groups showed contextual fluidity in expressing emotion and emotion talk that…

Inhibition of HIV-1 entry by the tricyclic coumarin GUT-70 through the modification of membrane fluidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuda, Kouki; Hattori, Shinichiro; Kariya, Ryusho

Membrane fusion between host cells and HIV-1 is the initial step in HIV-1 infection, and plasma membrane fluidity strongly influences infectivity. In the present study, we demonstrated that GUT-70, a natural product derived from Calophyllum brasiliense, stabilized plasma membrane fluidity, inhibited HIV-1 entry, and down-regulated the expression of CD4, CCR5, and CXCR4. Since GUT-70 also had an inhibitory effect on viral replication through the inhibition of NF-κB, it is expected to be used as a dual functional and viral mutation resistant reagent. Thus, these unique properties of GUT-70 enable the development of novel therapeutic agents against HIV-1 infection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi, Jae-Sung; Choo, Hyo-Jung; Cho, Bong-Rae

Lipid rafts are plasma membrane platforms mediating signal transduction pathways for cellular proliferation, differentiation and apoptosis. Here, we show that membrane fluidity was increased in HeLa cells following treatment with ginsenoside Rh2 (Rh2), as determined by cell staining with carboxy-laurdan (C-laurdan), a two-photon dye designed for measuring membrane hydrophobicity. In the presence of Rh2, caveolin-1 appeared in non-raft fractions after sucrose gradient ultracentrifugation. In addition, caveolin-1 and GM1, lipid raft landmarkers, were internalized within cells after exposure to Rh2, indicating that Rh2 might disrupt lipid rafts. Since cholesterol overloading, which fortifies lipid rafts, prevented an increase in Rh2-induced membrane fluidity,more » caveolin-1 internalization and apoptosis, lipid rafts appear to be essential for Rh2-induced apoptosis. Moreover, Rh2-induced Fas oligomerization was abolished following cholesterol overloading, and Rh2-induced apoptosis was inhibited following treatment with siRNA for Fas. This result suggests that Rh2 is a novel lipid raft disruptor leading to Fas oligomerization and apoptosis.« less

Magnesium activation of GTP hydrolysis or incubation in S-adenosyl-l-methionine reverses iron-56-particle-induced decrements in oxotremorine enhancement of K+-evoked striatal release of dopamine.

PubMed

Joseph, J A; Shukitt-Hale, B; McEwen, J; Rabin, B

1999-12-01

Previous research has determined that the deficits in motor behavior seen in aged animals irradiated with (56)Fe particles involved alterations in muscarinic receptor sensitivity. In the present experiments, we determined whether increasing either membrane fluidity by exposure of striatal slices from irradiated ((56)Fe particles) animals to S-adenosyl-l-methionine (SAM) or GTP hydrolysis with Mg(2+) would reverse this (56)Fe-particle-induced loss of muscarinic receptor sensitivity, as has been observed in aged animals. Results indicated that, while increasing Mg(2+) concentrations in the incubation medium was effective in reducing the radiation effects, SAM was able to effect some reversal of the radiation effects only at the lower concentration (200 microM). These results suggest that similar mechanisms may be involved in the deficits in signal transduction seen after (56)Fe-particle irradiation to those seen in aging, and that these may include changes in the membrane structure or composition that could alter subsequent responsiveness of transduction pathways. The results further suggest that, as has been reported previously, (56)Fe-particle irradiation may accelerate brain aging, and that since these HZE particles contribute at least 1% of the dose that astronauts would receive from cosmic rays, long-term exposure on extended space flights (e.g. to Mars) may produce similar deficits that could have immediate or delayed effects on behavior.

Direct measurements of irradiation-induced creep in micropillars of amorphous Cu{sub 56}Ti{sub 38}Ag{sub 6}, Zr{sub 52}Ni{sub 48}, Si, and SiO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Özerinç, Sezer; Kim, Hoe Joon; Averback, Robert S.

2015-01-14

We report in situ measurements of irradiation-induced creep on amorphous (a-) Cu{sub 56}Ti{sub 38}Ag{sub 6}, Zr{sub 52}Ni{sub 48}, Si, and SiO{sub 2}. Micropillars 1 μm in diameter and 2 μm in height were irradiated with ∼2 MeV heavy ions during uniaxial compression at room temperature. The creep measurements were performed using a custom mechanical testing apparatus utilizing a nanopositioner, a silicon beam transducer, and an interferometric laser displacement sensor. We observed Newtonian flow in all tested materials. For a-Cu{sub 56}Ti{sub 38}Ag{sub 6}, a-Zr{sub 52}Ni{sub 48}, a-Si, and Kr{sup +} irradiated a-SiO{sub 2} irradiation-induced fluidities were found to be nearly the same, ≈3 GPa{sup −1}more » dpa{sup −1}, whereas for Ne{sup +} irradiated a-SiO{sub 2} the fluidity was much higher, 83 GPa{sup −1} dpa{sup −1}. A fluidity of 3 GPa{sup −1} dpa{sup −1} can be explained by point-defect mediated plastic flow induced by nuclear collisions. The fluidity of a-SiO{sub 2} can also be explained by this model when nuclear stopping dominates the energy loss, but when the electronic stopping exceeds 1 keV/nm, stress relaxation in thermal spikes also contributes to the fluidity.« less

Erythrocyte membrane fluidity and indices of plasmatic oxidative damage after acute physical exercise in humans.

PubMed

Berzosa, C; Gómez-Trullén, E M; Piedrafita, E; Cebrián, I; Martínez-Ballarín, E; Miana-Mena, F J; Fuentes-Broto, L; García, J J

2011-06-01

Optimal levels of membrane fluidity are essential for numerous cell functions including cell growth, solute transport and signal transduction. Since exercise enhances free radical production, our aim was to evaluate in healthy male subjects the effects of an acute bout of maximal and submaximal exercise on the erythrocyte membrane fluidity and its possible relation to the oxidative damage overproduction due to exercise. Subjects (n = 34) performed three cycloergometric tests: a continuous progressive exercise, a strenuous exercise until exhaustion and an acute bout of exercise at an intensity corresponding to 70% of maximal work capacity for 30 min. Venous blood samples were collected before and immediately after these exercises. Erythrocyte membrane fluidity was assessed by fluorescence spectroscopy. Plasma malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations and carbonyl content of plasmatic proteins were used as an index of lipid and protein oxidation, respectively. Exercise produced a dramatic drop in the erythrocyte membrane fluidity as compared to resting time, but this was not accompanied by significant changes in the plasmatic MDA and 4-HDA concentrations. The highest erythrocyte membrane rigidity was detected immediately after strenuous exercise until exhaustion was performed. Protein carbonyl levels were higher after exhaustive exercises than at rest. Continuous progressive and strenuous exercises until exhaustion, but not submaximal workload, resulted in a significant enhanced accumulation of carbonylated proteins in the plasma. These findings are consistent with the idea that exercise exaggerates oxidative damage, which may contribute, at least partially, to explain the rigidity in the membrane of the erythrocytes due to acute exercise.

An Examination of Organizational Fluidity and Workplace Quality in a Community College Setting: An Internal Multi-Stakeholder Perspective

ERIC Educational Resources Information Center

Porter, Catherine L.

2013-01-01

Community colleges today are experiencing monumental shifts in their operating environments. Some of these changes are known, but many of them are not. They include shifts in curriculum, funding, and societal expectation to name a few. Through the constructs of high quality work environment and organizational fluidity theory, this research…

Growth-Environment Dependent Modulation of Staphylococcus aureus Branched-Chain to Straight-Chain Fatty Acid Ratio and Incorporation of Unsaturated Fatty Acids.

PubMed

Sen, Suranjana; Sirobhushanam, Sirisha; Johnson, Seth R; Song, Yang; Tefft, Ryan; Gatto, Craig; Wilkinson, Brian J

2016-01-01

The fatty acid composition of membrane glycerolipids is a major determinant of Staphylococcus aureus membrane biophysical properties that impacts key factors in cell physiology including susceptibility to membrane active antimicrobials, pathogenesis, and response to environmental stress. The fatty acids of S. aureus are considered to be a mixture of branched-chain fatty acids (BCFAs), which increase membrane fluidity, and straight-chain fatty acids (SCFAs) that decrease it. The balance of BCFAs and SCFAs in USA300 strain JE2 and strain SH1000 was affected considerably by differences in the conventional laboratory medium in which the strains were grown with media such as Mueller-Hinton broth and Luria broth resulting in high BCFAs and low SCFAs, whereas growth in Tryptic Soy Broth and Brain-Heart Infusion broth led to reduction in BCFAs and an increase in SCFAs. Straight-chain unsaturated fatty acids (SCUFAs) were not detected. However, when S. aureus was grown ex vivo in serum, the fatty acid composition was radically different with SCUFAs, which increase membrane fluidity, making up a substantial proportion of the total (<25%) with SCFAs (>37%) and BCFAs (>36%) making up the rest. Staphyloxanthin, an additional major membrane lipid component unique to S. aureus, tended to be greater in content in cells with high BCFAs or SCUFAs. Cells with high staphyloxanthin content had a lower membrane fluidity that was attributed to increased production of staphyloxanthin. S. aureus saves energy and carbon by utilizing host fatty acids for part of its total fatty acids when growing in serum, which may impact biophysical properties and pathogenesis given the role of SCUFAs in virulence. The nutritional environment in which S. aureus is grown in vitro or in vivo in an infection is likely to be a major determinant of membrane fatty acid composition.

Electrosteric stabilization of heteroflocculating suspensions and its application to the processing of self-compacting engineered cementitious composites

NASA Astrophysics Data System (ADS)

Kong, Hyun-Joon

This dissertation investigates a dispersion/stabilization technique to improve the fluidity of heteroflocculating concentrated suspensions, and applies the technique to develop self-compacting Engineered Cementitious Composites (ECC), defined as a cementitious material which compacts without any external consolidation in the fresh state, while exhibiting strain-hardening performance in the hardened state. To meet the criteria of micromechanical design to achieve the ductile performance and processing design to attain high fluidity, this work has focused on preparing cement suspensions with low viscosity and high cohesiveness at a particle loading determined by the micromechanical design. Therefore, the goal of this work is to quantify how to adjust the strong flocculation between cement particles due to electrostatic and van der Waals attractive forces. For this purpose, a strong polyelectrolyte, melamine formaldehyde sulfonate (MFS), to disperse the oppositely-charged particles present in the cement dispersion, is combined with a non-ionic polymer, hydroxypropylmethylcellulose (HPMC). The combination of these two polymers to prevent re-flocculation leads to "complementary electrosteric dispersion/ stabilization". With these polymers, suspensions with the desired fluidity for processing are obtained. To quantify the roles of the two polymers in imparting stability, a heteroflocculating model suspension was developed, which facilitates the control of the interactions typical of cement suspensions, but without irreversible hydration. This model suspension is composed of alumina and silica particles, which bear surface potentials of opposite sign at intermediate pHs, as well as has a comparable magnitude of the Hamaker constant as compared to cement particles. As a result, the model system displays not only van der Waals attraction but also electrostatic attraction between dissimilar particles. Rheological studies of the model system stabilized by MFS and HPMC show behavior identical to that of the cement suspensions, allowing the model system to be used to interpret the role of the stabilizers in altering the system microstructure and fluidity. Finally, the self-compacting performance of fresh ECC mixes made with the electrosterically stabilized fresh matrix mix and the ductile strain-hardening performance of the hardened ECC were demonstrated.

In vitro analysis of the effect of alkyl-chain length of anionic surfactants on the skin by using a reconstructed human epidermal model.

PubMed

Yamaguchi, Fumiko; Watanabe, Shin-Ichi; Harada, Fusae; Miyake, Miyuki; Yoshida, Masaki; Okano, Tomomichi

2014-01-01

We investigated the effect of the alkyl-chain length of anionic surfactants on the skin using an in vitro model. The evaluated anionic surfactants were sodium alkyl sulfate (AS) and sodium fatty acid methyl ester sulfonate (MES), which had different alkyl-chain lengths (C8-C14). Skin tissue damage and permeability were examined using a reconstructed human epidermal model, LabCyte EPI-MODEL24. Skin tissue damage was examined by measuring cytotoxicity with an MTT assay. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) and liquid chromatography/mass spectrometry (LC/MS) were used to detect surfactants that permeated into the assay medium through an epidermal model. To assess the permeation mechanism and cell damage caused by the surfactants through the epidermis, we evaluated the structural changes of Bovine Serum Albumin (BSA), used as a simple model protein, and the fluidity of 1,2-dipalmitoyl-sn-glycero-3-phosphpcholine (DPPC) liposome, which serves as one of the most abundant phospholipid models of living cell membranes in the epidermis. The effects of the surfactants on the proteins were measured using Circular Dichroism (CD) spectroscopy, while the effects on membrane fluidity were investigated by electron spin resonance (ESR) spectroscopy. ET50 (the 50% median effective time) increased as follows: C10 < C12 < C8 < C14 in AS and C8, C10 < C12 < C14 in MES. The order of permeation through the LabCyte EPI-MODEL24 was C10 > C12 > C14, for both AS and MES. For both AS and MES, the order parameter, which is the criteria for the microscopic viscosity of lipid bilayers, increased as follows: C10 < C12 < C14, which means the membrane fluidity is C10 > C12 > C14. It was determined that the difference in skin tissue damage in the LabCyte EPI-MODEL24 with C10 to C14 AS and MES was caused by the difference in permeation and cell membrane fluidity through the lipid bilayer path in the epidermis.

[Study on nano-CaCO3 applicated in Xin Yue Shu Capsules preliminarily].

PubMed

Jiang, Yan-Rong; Zhang, Zhen-Hai; Cui, Li; He, Jun-Jie; Hu, Shao-Ying; Jia, Xiao-Bin

2012-11-01

To investigate the characteristics of nano-CaCO3 applicated in Xin Yue Shu Capsules. Studied the effect of different dosages of aerosil or nano-CaCO3 on fluidity, bulk density, moisture absorption of Xin Yue Shu capsules spray drying powder. In vitro dissolution and ferulic acid stability of Xin Yue Shu capsules was observed. It significantly improved powder fluidity and bulk density of Xin Yue Shu spray drying powder when aerosil or nano-CaCO3 was added. But there was no significant effect on powder moisture absorption, ferulic acid in vitro dissolution and ferulic acid stability. The effect of Nano-CaCO3 on improving powder fluidity and bulk density applicated in the spray drying powder of traditional Chinese medicine deserves studying further.

Interaction of curcumin with 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine liposomes: Intercalation of rhamnolipids enhances membrane fluidity, permeability and stability of drug molecule.

PubMed

Moussa, Zeinab; Chebl, Mazhar; Patra, Digambara

2017-01-01

Stability of curcumin in neutral and alkaline buffer conditions has been a serious concern for its medicinal applications. We demonstrate that the stability of curucmin can be improved in 1,2-Dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. Curcumin strongly partition into liquid crystalline phase compared to solid gel phase of DSPC liposomes. Variation of fluorescence intensity of curcumin associated with liposomes with temperature successfully determines phase transition temperature of DSPC liposomes. However, at higher molar ratio curcumin can influence phase transition temperature by intercalating into deep hydrophobic layer of liposomes and facilitating fusion of two membrane phases. Rhamnolipids (RLs) are recently being applied for various biomedical applications. Here, we have explored new insight on intercalation of rhamnolipids with DSPC liposomes. Intercalation of rhamnolipids exceptionally increases partition of curcumin into solid gel phase of DSPC liposomes, whereas this increase is moderate in liquid crystalline phase. Fluorescence quenching study establishes that permeability and fluidity of the DSPC liposomes are enhanced in the presence of RLs. Membrane permeability and fluidity can be improved further by increasing the percentage of RLs in DSPC liposomes. The phase transition temperature of DSPC liposomes decreases with increase in percentage of RLs in DSPC liposomes by encouraging fusion between solid gel and liquid crystalline phases. Intercalation of RLs is found to further boost stability of drug, curcumin, in DSPC liposomes. Thus, mixing RLs with DSPC liposomes could potentially serve as a good candidate for drug delivery application. Copyright © 2016 Elsevier B.V. All rights reserved.

Gender fluidity and child abuse: A personal view.

PubMed

Lewis, Charles

2017-12-01

Gender fluidity and a failure to respect biological norms may have potentially horrific implications for children and adolescents who express doubt about their bodies. Are transgender activists driving an agenda that will result in inappropriate interventions that block normal development in children and adolescents from which there can be no return? Can the Law protect children and adolescents from harm committed with the intention of helping them?

Effect of growth temperature, surface type and incubation time on the resistance of Staphylococcus aureus biofilms to disinfectants.

PubMed

Abdallah, Marwan; Chataigne, Gabrielle; Ferreira-Theret, Pauline; Benoliel, Corinne; Drider, Djamel; Dhulster, Pascal; Chihib, Nour-Eddine

2014-03-01

The goal of this study was to investigate the effect of the environmental conditions such as the temperature change, incubation time and surface type on the resistance of Staphylococcus aureus biofilms to disinfectants. The antibiofilm assays were performed against biofilms grown at 20 °C, 30 °C and 37 °C, on the stainless steel and polycarbonate, during 24 and 48 h. The involvement of the biofilm matrix and the bacterial membrane fluidity in the resistance of sessile cells were investigated. Our results show that the efficiency of disinfectants was dependent on the growth temperature, the surface type and the disinfectant product. The increase of growth temperature from 20 °C to 37 °C, with an incubation time of 24 h, increased the resistance of biofilms to cationic antimicrobials. This change of growth temperature did not affect the major content of the biofilm matrix, but it decreased the membrane fluidity of sessile cells through the increase of the anteiso-C19 relative amount. The increase of the biofilm resistance to disinfectants, with the rise of the incubation time, was dependent on both growth temperature and disinfectant product. The increase of the biofilm age also promoted increases in the matrix production and the membrane fluidity of sessile cells. The resistance of S. aureus biofilm seems to depend on the environment of the biofilm formation and involves both extracellular matrix and membrane fluidity of sessile cells. Our study represents the first report describing the impact of environmental conditions on the matrix production, sessile cells membrane fluidity and resistance of S. aureus biofilms to disinfectants.

Material-induced Senescence (MIS): Fluidity Induces Senescent Type Cell Death of Lung Cancer Cells via Insulin-Like Growth Factor Binding Protein 5.

PubMed

Mano, Sharmy Saimon; Uto, Koichiro; Ebara, Mitsuhiro

2017-01-01

Objective: We propose here material-induced senescence (MIS) as a new therapeutic concept that limits cancer progression by stable cell cycle arrest. This study examined for the first time the effect of material fluidity on cellular senescence in lung carcinoma using poly(ε-caprolactone- co -D, L-lactide) (P(CL- co -DLLA)) with tunable elasticity and fluidity. Methods: The fluidity was varied by chemically crosslinking the polymer networks: the crosslinked P(CL- co -DLLA) shows solid-like properties with a stiffness of 260 kPa, while the non-crosslinked polymer exists in a quasi-liquid state with loss and storage moduli of 33 kPa and 11 kPa, respectively. Results: We found that cancer cells growing on the non-crosslinked, fluidic substrate undergo a non-apoptotic form of cell death and the cell cycle was accumulated in a G0/G1 phase. Next, we investigated the expression of biomarkers that are associated with cancer pathways. The cancer cells on the fluidic substrate expressed several biomarkers associated with senescence such as insulin-like growth factor binding protein 5 (IGFBP5). This result indicates that when cancer cells sense fluidity in their surroundings, the cells express IGFBP5, which in turn triggers the expression of tumor suppressor protein 53 and initiates cell cycle arrest at the G1 phase followed by cellular senescence. Furthermore, the cancer cells on the fluidic substrate maintained their epithelial phenotype, suggesting that the cancer cells do not undergo epithelial to mesenchymal transition. Conclusion: By considering these results as the fundamental information for MIS, our system could be applied to induce senescence in treatment-resistant cancers such as metastatic cancer or cancer stem cells.

Membrane fluidity profiles as deduced by saturation-recovery EPR measurements of spin-lattice relaxation times of spin labels

NASA Astrophysics Data System (ADS)

Mainali, Laxman; Feix, Jimmy B.; Hyde, James S.; Subczynski, Witold K.

2011-10-01

There are no easily obtainable EPR spectral parameters for lipid spin labels that describe profiles of membrane fluidity. The order parameter, which is most often used as a measure of membrane fluidity, describes the amplitude of wobbling motion of alkyl chains relative to the membrane normal and does not contain explicitly time or velocity. Thus, this parameter can be considered as nondynamic. The spin-lattice relaxation rate ( T1-1) obtained from saturation-recovery EPR measurements of lipid spin labels in deoxygenated samples depends primarily on the rotational correlation time of the nitroxide moiety within the lipid bilayer. Thus, T1-1 can be used as a convenient quantitative measure of membrane fluidity that reflects local membrane dynamics. T1-1 profiles obtained for 1-palmitoyl-2-( n-doxylstearoyl)phosphatidylcholine ( n-PC) spin labels in dimyristoylphosphatidylcholine (DMPC) membranes with and without 50 mol% cholesterol are presented in parallel with profiles of the rotational diffusion coefficient, R⊥, obtained from simulation of EPR spectra using Freed's model. These profiles are compared with profiles of the order parameter obtained directly from EPR spectra and with profiles of the order parameter obtained from simulation of EPR spectra. It is shown that T1-1 and R⊥ profiles reveal changes in membrane fluidity that depend on the motional properties of the lipid alkyl chain. We find that cholesterol has a rigidifying effect only to the depth occupied by the rigid steroid ring structure and a fluidizing effect at deeper locations. These effects cannot be differentiated by profiles of the order parameter. All profiles in this study were obtained at X-band (9.5 GHz).

Combination of 1H nuclear magnetic resonance spectroscopy and principal component analysis to evaluate the lipid fluidity of flutamide-encapsulated lipid nanoemulsions.

PubMed

Takegami, Shigehiko; Ueyama, Keita; Konishi, Atsuko; Kitade, Tatsuya

2018-06-06

The lipid fluidity of various lipid nanoemulsions (LNEs) without and with flutamide (FT) and containing one of two neutral lipids, one of four phosphatidylcholines as a surfactant, and sodium palmitate as a cosurfactant was investigated by the combination of 1 H nuclear magnetic resonance (NMR) spectroscopy and principal component analysis (PCA). In the 1 H NMR spectra, the peaks from the methylene groups of the neutral lipids and surfactants for all LNE preparations showed downfield shifts with increasing temperature from 20 to 60 °C. PCA was applied to the 1 H NMR spectral data obtained for the LNEs. The PCA resulted in a model in which the first two principal components (PCs) extracted 88% of the total spectral variation; the first PC (PC-1) axis and second PC (PC-2) axis accounted for 73 and 15%, respectively, of the total spectral variation. The Score-1 values for PC-1 plotted against temperature revealed the existence of two clusters, which were defined by the neutral lipid of the LNE preparations. Meanwhile, the Score-2 values decreased with rising temperature and reflected the increase in lipid fluidity of each LNE preparation, consistent with fluorescence anisotropy measurements. In addition, the changes of Score-2 values with temperature for LNE preparations with FT were smaller than those for LNE preparations without FT. This indicates that FT encapsulated in LNE particles markedly suppressed the increase in lipid fluidity of LNE particles with rising temperature. Thus, PCA of 1 H NMR spectra will become a powerful tool to analyze the lipid fluidity of lipid nanoparticles. Graphical abstract ᅟ.

Photopolymerization of Dienoyl Lipids Creates Planar Supported Poly(lipid) Membranes with Retained Fluidity.

PubMed

Orosz, Kristina S; Jones, Ian W; Keogh, John P; Smith, Christopher M; Griffin, Kaitlyn R; Xu, Juhua; Comi, Troy J; Hall, H K; Saavedra, S Scott

2016-02-16

Polymerization of substrate-supported bilayers composed of dienoylphosphatidylcholine (PC) lipids is known to greatly enhance their chemical and mechanical stability; however, the effects of polymerization on membrane fluidity have not been investigated. Here planar supported lipid bilayers (PSLBs) composed of dienoyl PCs on glass substrates were examined to assess the degree to which UV-initiated polymerization affects lateral lipid mobility. Fluorescence recovery after photobleaching (FRAP) was used to measure the diffusion coefficients (D) and mobile fractions of rhodamine-DOPE in unpolymerized and polymerized PSLBs composed of bis-sorbyl phosphatidylcholine (bis-SorbPC), mono-sorbyl-phosphatidylcholine (mono-SorbPC), bis-dienoyl-phosphatidylcholine (bis-DenPC), and mono-dienoyl phosphatidylcholine (mono-DenPC). Polymerization was performed in both the Lα and Lβ phase for each lipid. In all cases, polymerization reduced membrane fluidity; however, measurable lateral diffusion was retained which is attributed to a low degree of polymerization. The D values for sorbyl lipids were less than those of the denoyl lipids; this may be a consequence of the distal location of polymerizable group in the sorbyl lipids which may facilitate interleaflet bonding. The D values measured after polymerization were 0.1-0.8 of those measured before polymerization, a range that corresponds to fluidity intermediate between that of a Lα phase and a Lβ phase. This D range is comparable to ratios of D values reported for liquid-disordered (Ld) and liquid-ordered (Lo) lipid phases and indicates that the effect of UV polymerization on lateral diffusion in a dienoyl PSLB is similar to the transition from a Ld phase to a Lo phase. The partial retention of fluidity in UV-polymerized PSLBs, their enhanced stability, and the activity of incorporated transmembrane proteins and peptides is discussed.

Photopolymerization of dienoyl lipids creates planar supported poly(lipid) membranes with retained fluidity

PubMed Central

Orosz, Kristina S.; Jones, Ian W.; Keogh, John P.; Smith, Christopher M.; Griffin, Kaitlyn R.; Xu, Juhua; Comi, Troy J.; Hall, H. K.

2016-01-01

Polymerization of substrate-supported bilayers composed of dienoyl phosphatidylcholine (PC) lipids is known to greatly enhance their chemical and mechanical stability, however the effects of polymerization on membrane fluidity have not been investigated. Here planar supported lipid bilayers (PSLBs) composed of dienoyl PCs on glass substrates were examined to assess the degree to which UV-initiated polymerization affects lateral lipid mobility. Fluorescence recovery after photobleaching (FRAP) was used to measure the diffusion coefficients (D) and mobile fractions of rhodamine-DOPE in unpolymerized and polymerized PSLBs composed of bis-sorbyl phosphatidylcholine (bis-SorbPC), mono-sorbyl phosphatidylcholine (mono-SorbPC), bis-dienoyl phosphatidylcholine (bis-DenPC) and mono-dienoyl phosphatidylcholine (mono-DenPC). Polymerization was performed in both the Lα and Lβ phase for each lipid. In all cases, polymerization reduced membrane fluidity, however measurable lateral diffusion was retained which is attributed to a low degree of polymerization. The D values for sorbyl lipids were less than those of the denoyl lipids; this may be a consequence of the distal location of polymerizable group in the sorbyl lipids which may facilitate inter-leaflet bonding. The D values measured after polymerization were 0.1 to 0.8 of those measured before polymerization, a range that corresponds to fluidity intermediate between that of a Lα phase and a Lβ phase. This D range is comparable to ratios of D values reported for liquid-disordered (Ld) and liquid-ordered (Lo) lipid phases, and indicates that the effect of UV polymerization on lateral diffusion in a dienoyl PSLB is similar to the transition from a Ld phase to a Lo phase. The partial retention of fluidity in UV polymerized PSLBs, their enhanced stability, and the activity of incorporated transmembrane proteins and peptides is discussed. PMID:26794208

Influence of MLS laser radiation on erythrocyte membrane fluidity and secondary structure of human serum albumin.

PubMed

Pasternak, Kamila; Nowacka, Olga; Wróbel, Dominika; Pieszyński, Ireneusz; Bryszewska, Maria; Kujawa, Jolanta

2014-03-01

The biostimulating activity of low level laser radiation of various wavelengths and energy doses is widely documented in the literature, but the mechanisms of the intracellular reactions involved are not precisely known. The aim of this paper is to evaluate the influence of low level laser radiation from an multiwave locked system (MLS) of two wavelengths (wavelength = 808 nm in continuous emission and 905 nm in pulsed emission) on the human erythrocyte membrane and on the secondary structure of human serum albumin (HSA). Human erythrocytes membranes and HSA were irradiated with laser light of low intensity with surface energy density ranging from 0.46 to 4.9 J cm(-2) and surface energy power density 195 mW cm(-2) (1,000 Hz) and 230 mW cm(-2) (2,000 Hz). Structural and functional changes in the erythrocyte membrane were characterized by its fluidity, while changes in the protein were monitored by its secondary structure. Dose-dependent changes in erythrocyte membrane fluidity were induced by near-infrared laser radiation. Slight changes in the secondary structure of HSA were also noted. MLS laser radiation influences the structure and function of the human erythrocyte membrane resulting in a change in fluidity.

Neutralizing antibodies decrease the envelope fluidity of HIV-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, Shinji; Monde, Kazuaki; Tanaka, Yuetsu

2008-01-05

For successful penetration of HIV-1, the formation of a fusion pore may be required in order to accumulate critical numbers of fusion-activated gp41 with the help of fluidization of the plasma membrane and viral envelope. An increase in temperature to 40 {sup o}C after viral adsorption at 25 {sup o}C enhanced the infectivity by 1.4-fold. The enhanced infectivity was inhibited by an anti-CXCR4 peptide, T140, and anti-V3 monoclonal antibodies (0.5{beta} and 694/98-D) by post-attachment neutralization, but not by non-neutralizing antibodies (670-30D and 246-D) specific for the C5 of gp120 and cluster I of gp41, respectively. Anti-HLA-II and an anti-HTLV-I gp46more » antibody, LAT27, neutralized the molecule-carrying HIV-1{sub C-2(MT-2)}. The anti-V3 antibodies suppressed the fluidity of the HIV-1{sub C-2} envelope, whereas the non-neutralizing antibodies did not. The anti-HLA-II antibody decreased the envelope fluidity of HIV-1{sub C-2(MT-2)}, but not that of HIV-1{sub C-2}. Therefore, fluidity suppression by these antibodies represents an important neutralization mechanism, in addition to inhibition of viral attachment.« less

In vitro effects of fermented papaya (Carica papaya, L.) on platelets obtained from patients with type 2 diabetes.

PubMed

Raffaelli, F; Nanetti, L; Montecchiani, G; Borroni, F; Salvolini, E; Faloia, E; Ferretti, G; Mazzanti, L; Vignini, A

2015-02-01

Oxidative stress is associated with insulin resistance pathogenesis, insulin secretion deficiency, and complication onset. Fermented papaya preparation (FPP), a dietary supplement obtained by fermentation of the papaya fruit, may be used as an antioxidant in the prevention of diabetic complications. Platelets from 30 patients with type 2 diabetes mellitus (DM 2) and 15 healthy subjects were analyzed to evaluate the in vitro effects of FPP incubation. Na(+)/K(+)-adenosine triphosphatase (ATPase) activity, membrane fluidity, total antioxidant capacity (TAC), superoxide dismutase (SOD) activity, and conjugated diene levels were determined. In vitro FPP incubation improved platelet function, by enhancing Na(+)/K(+)-ATPase activity and membrane fluidity, and ameliorated the antioxidant system functionality, through an increase in TAC and SOD activity and a parallel decrease in conjugated diene levels in patients with DM 2. Our data suggest that the incubation with FPP may have a protective effect on platelets from patients with DM 2, by preventing the progression of oxidative damage associated with diabetes and its complications. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanoscale evaluation of lubricity on well-defined polymer brush surfaces using QCM-D and AFM.

PubMed

Kitano, Kazuhiko; Inoue, Yuuki; Matsuno, Ryosuke; Takai, Madoka; Ishihara, Kazuhiko

2009-11-01

For preparing a "highly lubricated biointerface", which has both excellent lubricity and biocompatibility, we investigated the factors responsible for resistance to friction during polymer grafting. We prepared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(methyl methacrylate) (PMMA) brush layers with high graft density and well-controlled thickness using atom transfer radical polymerization (ATRP). We measured the water absorptivity in the polymer brush layers and the viscoelasticity of the polymer-hydrated layers using a quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The PMPC brush layer had the highest water absorptivity, while the PMPC-hydrated layer had the highest fluidity. The friction properties of the polymer brush layers were determined in air, water, and toluene by atomic force microscopy (AFM). The friction on each polymer brush decreased only when a good solvent was chosen for each polymer. In conclusion, the brush layer possessing high water absorptivity and fluidity in water contributes to reduce friction. PMPC grafting is an effective and promising method for obtaining highly lubricated biointerfaces.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morales, Noppawan Phumala; Charlermchoung, Chalermkhwan; Luechapudiporn, Rataya

Atherosclerosis-related vascular complications in {beta}-thalassemia/hemoglobin E ({beta}-thal/Hb E) patients may result from iron induced oxidation of lipoproteins. To identify the specific site of oxidative damage, changes in lipid fluidity at different regions in LDL and HDL particle were investigated using two fluorescence probes and two ESR spin probes. The magnitude of increased lipid fluidity in thalassemic lipoproteins was dependent on the location of the probes. In hydrophobic region, the rotational correlation times for 16-doxyl stearic acid and DPH anisotropy were markedly changed in LDL and HDL of the patients. In the surface region, there was only a slight change inmore » the order parameter (S) for 5-doxyl stearic acid and TMA-DPH anisotropy. Lipid fluidity at the core of LDL and HDL showed good correlation with oxidative stress markers, the ratio of CL/CO, and the level of {alpha}-tocopherol, suggesting that hydrophobic region of thalassemic lipoprotein was a target site for oxidative damage.« less

Bile salts stimulate mucin secretion by cultured dog gallbladder epithelial cells independent of their detergent effect.

PubMed

Klinkspoor, J H; Yoshida, T; Lee, S P

1998-05-15

1. Bile salts stimulate mucin secretion by the gallbladder epithelium. We have investigated whether this stimulatory effect is due to a detergent effect of bile salts. 2. The bile salts taurocholic acid (TC) and tauroursodeoxycholic acid (TUDC) and the detergents Triton X-100 (12.5-400 microM) and Tween-20 (0.1-3.2 mM) were applied to monolayers of cultured dog gallbladder epithelial cells. Mucin secretion was studied by measuring the secretion of [3H]N-acetyl-d-glucosamine-labelled glycoproteins. We also attempted to alter the fluidity of the apical membrane of the cells through extraction of cholesterol with beta-cyclodextrin (2.5-15 mM). The effect on TUDC-induced mucin secretion was studied. Cell viability was assessed by measuring lactate dehydrogenase (LDH) leakage or 51Cr release. 3. In contrast with the bile salts, the detergents were not able to cause an increase in mucin secretion without causing concomitant cell lysis. Concentrations of detergent that increased mucin release (>100 microM Triton X-100, >0.8 mM Tween-20), caused increased LDH release. Incubation with beta-cyclodextrin resulted in effective extraction of cholesterol without causing an increase in 51Cr release. However, no effect of the presumed altered membrane fluidity on TUDC (10 mM)-induced mucin secretion was observed. 4. The stimulatory effect of bile salts on mucin secretion by gallbladder epithelial cells is not affected by the fluidity of the apical membrane of the cells and also cannot be mimicked by other detergents. We conclude that the ability of bile salts to cause mucin secretion by the gallbladder epithelium is not determined by their detergent properties.

Coal lithotypes before and after saturation with CO2; insights from micro- and mesoporosity, fluidity, and functional group distribution

USGS Publications Warehouse

Mastalerz, Maria; Drobniak, A.; Walker, R.; Morse, D.

2010-01-01

Four lithotypes, vitrain, bright clarain, clarain, and fusain, were hand-picked from the core of the Pennsylvanian Springfield Coal Member (Petersburg Formation) in Illinois. These lithotypes were analyzed petrographically and for meso- and micropore characteristics, functional group distribution using FTIR techniques, and fluidity. High-pressure CO2 adsorption isotherm analyses of these lithotypes were performed and, subsequently, all samples were reanalyzed in order to investigate the effects of CO2. After the high-pressure adsorption isotherm analysis was conducted and the samples were reanalyzed, there was a decrease in BET surface area for vitrain from 31.5m2/g in the original sample to 28.5m2/g, as determined by low-pressure nitrogen adsorption. Bright clarain and clarain recorded a minimal decrease in BET surface area, whereas for fusain there was an increase from 6.6m2/g to 7.9m2/g. Using low-pressure CO2 adsorption techniques, a small decrease in the quantity of the adsorbed CO2 is recorded for vitrain and bright clarain, no difference is observed for clarain, and there is an increase in the quantity of the adsorbed CO2 for fusain. Comparison of the FTIR spectra before and after CO2 injection for all lithotypes showed no differences with respect to functional group distribution, testifying against chemical nature of CO2 adsorption. Gieseler plastometry shows that: 1) softening temperature is higher for the post-CO2 sample (389.5??C vs. 386??C); 2) solidification temperature is lower for the post-CO2 sample (443.5??C vs. 451??C); and 3) the maximum fluidity is significantly lower for the post-CO2 sample (4 ddpm vs. 14 ddpm). ?? 2010 Elsevier B.V.

Liposomes for Topical Use: A Physico-Chemical Comparison of Vesicles Prepared from Egg or Soy Lecithin

PubMed Central

Budai, Lívia; Kaszás, Nóra; Gróf, Pál; Lenti, Katalin; Maghami, Katayoon; Antal, István; Klebovich, Imre; Petrikovics, Ilona; Budai, Marianna

2013-01-01

Developments in nanotechnology and in the formulation of liposomal systems provide the opportunity for cosmetic dermatology to design novel delivery systems. Determination of their physico-chemical parameters has importance when developing a nano-delivery system. The present study highlights some technological aspects/characteristics of liposomes formulated from egg or soy lecithins for topical use. Alterations in the pH, viscosity, surface tension, and microscopic/macroscopic appearance of these vesicular systems were investigated. The chemical composition of the two types of lecithin was checked by mass spectrometry. Caffeine, as a model molecule, was encapsulated into multilamellar vesicles prepared from the two types of lecithin: then zeta potential, membrane fluidity, and encapsulation efficiency were compared. According to our observations, samples prepared from the two lecithins altered the pH in opposite directions: egg lecithin increased it while soy lecithin decreased it with increased lipid concentration. Our EPR spectroscopic results showed that the binding of caffeine did not change the membrane fluidity in the temperature range of possible topical use (measured between 2 and 50 °C). Combining our results on encapsulation efficiency for caffeine (about 30% for both lecithins) with those on membrane fluidity data, we concluded that the interaction of caffeine with the liposomal membrane does not change the rotational motion of the lipid molecules close to the head group region. In conclusion, topical use of egg lecithin for liposomal formulations can be preferred if there are no differences in the physico-chemical properties due to the encapsulated drugs, because the physiological effects of egg lecithin vesicles on skin are significantly better than that of soy lecithin liposomes. PMID:24482779

A selective estrogen receptor modulator, tamoxifen, and membrane fluidity of erythrocytes in normotensive and hypertensive postmenopausal women: an electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Nishio, Ichiro

2005-08-01

Recent studies have shown that tamoxifen, which belongs to a group called selective estrogen receptor modulators (SERM), may exert protective effects against cardiovascular diseases and stroke in postmenopausal women. On the other hand, abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension, stroke, and other cardiovascular diseases. The present study was performed to investigate the effects of tamoxifen on cell membrane fluidity (a reciprocal value of membrane microviscosity) in normotensive and hypertensive postmenopausal women. We used an electron paramagnetic resonance (EPR) and spin-labeling method. Tamoxifen significantly decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in normotensive postmenopausal women (mean +/- SEM, order parameter value; control 0.719 +/- 0.002, n = 41; tamoxifen 1 x 10(-7) mol/L 0.704 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-6) mol/L 0.696 +/- 0.002, n = 41, P < .0001; tamoxifen 1 x 10(-5) mol/L 0.692 +/- 0.002, n = 41, P < .0001). The finding indicated that tamoxifen increased the membrane fluidity and improved the membrane microviscosity of erythrocytes. The membrane action of tamoxifen was antagonized by the estrogen receptor antagonist ICI 182,780. The effect of tamoxifen was significantly potentiated by the nitric oxide (NO) donors, l-arginine and S-nitroso-N-acetylpenicillamine, and a cGMP analog 8-bromo-cGMP. In contrast, the change evoked by tamoxifen was counteracted by the NO synthase inhibitors N(G)-nitro-l-arginine-methyl-ester and asymmetric dimethyl-l-arginine. In hypertensive postmenopausal women, the membrane fluidity of erythrocytes was significantly lower than in normotensive postmenopausal women. The effect of tamoxifen on the membrane fluidity was more pronounced in hypertensive postmenopausal women than in normotensive postmenopausal women. These results showed that tamoxifen increased the membrane fluidity of erythrocytes and improved the rigidity of cell membranes in postmenopausal women, to some extent, through the NO- and cGMP-dependent mechanisms. Furthermore, the greater effect of tamoxifen in hypertensive postmenopausal women suggests that tamoxifen could have a beneficial effect in regulating the blood rheologic behavior and in the improvement of the microcirculation in hypertension.

Growth, fatty acid profile in major lipid classes and lipid fluidity of Aurantiochytrium mangrovei SK-02 As a function of growth temperature.

PubMed

Chodchoey, Kanokwan; Verduyn, Cornelis

2012-01-01

Aurantiochytrium mangrovei Sk-02 was grown in a medium containing glucose (40 g/l), yeast extract (10 g/L) and sea salts (15 g/L) at temperatures ranging from 12 to 35°C. The fastest growth (µmax= 0.15 h(-1)) and highest fatty acid content of 415 mg/g-dry cell weight were found in the cells grown at 30°C. However, the cells grown at 12°C showed the highest percentage of polyunsaturated fatty acid (PUFA) (48.6% of total fatty acid). The percentage of docosahexaenoic acid (DHA) and pentadecanoic acid (C15:0) decreased with an increase in the growth temperature, whereas, palmitic acid (C16:0), stearic acid (C18:0) and DPA (C22:5n6) increased with an increase in the growth temperature. The composition of the major lipid class (%w/w) was slightly affected by the growth temperature. The fluidity of the organelle membrane or intracellular lipid (by DPH measurement) decreased with an increase in the growth temperatures, while the plasma membrane fluidity (by TMA-DPH measurement) could still maintain its fluidity in a wide range of temperatures (15 - 37°C). Furthermore, the distribution of DHA was found to be higher (36 - 54%) in phospholipid (PL) as compared to neutral lipid (NL) (20 - 41%).

Religion, social mobility and education in Scotland.

PubMed

Paterson, Lindsay; Iannelli, Cristina

2006-09-01

The relationship among religion, education and social mobility in Scotland is analysed statistically using the Scottish Household Survey of 2001. The large sample size allows much greater statistical power for this purpose than any previous source, and thus allows a more reliable assessment of claims that the stratifying effect of religion in Scotland may have declined. The questions investigated are as follows. What are the religious differences in the distributions of class origins and class destinations, in the movement between these (absolute mobility), and in the association of these (relative mobility, or social fluidity)? Do changes in social fluidity across cohorts vary among people with different religious affiliation? Are there religious differences in the association of origins and education, in the association of education and destinations, or in the role of education in social fluidity, and do any of these vary over cohorts? The conclusions are that, in younger cohorts, there is no religious difference in social status, and that in older cohorts Catholics are generally of lower status than Protestants and the non-religious. Social fluidity does not, however, vary among religious groups, even for older cohorts, and does not change over time. The reason for convergence in social status of religious groups over time is probably the equalizing of educational attainment among the groups: there is no evidence for any of the cohorts that the labour-market rewards to education differ by religion.

Simulated microgravity impacts the plant plasmalemma lipid bilayer

NASA Astrophysics Data System (ADS)

Nedukha, Olena; Berkovich, Yuliy A.; Vorobyeva, Tamara; Grakhov, Volodimir; Klimenko, Elena; Zhupanov, Ivan; Jadko, Sergiy

Biological membranes, especially the plasmalemma, and their properties and functions can be considered one of the most sensitive indicators of gravity interaction or alteration of gravity, respectively. Studies on the molecular basis of cellular signal perception and transduction are very important in order to understand signal responses at the cellular and organism level. The plasmalemma lipid bilayer is the boundary between the cell internal and external environment and mediates communication between them. Therefore, we studied the content and composition of lipids, saturated and unsaturated fatty acids, sterols, and microviscosity in the plasmalemma isolated from pea seedling roots and epicotyls grown in the stationary conditions and under slow horizontal clinorotation. In addition, lipid peroxidation intensity of intact roots was also identified. The plasmalemma fraction was isolated by the two-phase aquatic-polymer system optimized for pea using a centrifuge Optima L-90K. Lipid bilayer components were determined by using highly effective liquid chromatography with a system Angilent 1100 (Germany). Spontaneous chemiluminescence intensity was measured with a chemiluminometer ChLMTS-01. The obtained data showed that plasmalemma investigated parameters are sensitive to clinorotation, namely: increasing or decreasing the different lipids content, among which, phospho- and glycolipids were dominated, as well as changes in the content of saturated and unsaturated fatty acids and sterols. A degree of plasmalemma sensitivity to clinorotation was higher for the root plasmalemma than epicocotyl ones. This distinguish may be naturally explained by the differences in the structure, cell types, growth, and specific functions of a root and an epicotyl, those are the most complicated in roots. An index of unsaturation under clinorotation was similar to that in the stationary conditions as a result of the certain balance between changes in the content of saturated and unsaturated fatty acids, that maintains the plasmalemma fluidity in the normal limits, and it may be considered as an adaptive pattern. This assumption was directly confirmed by the data on plasmalemma fluidity in control and under clinorotation defined by electron paramagnetic resonance spectrometer Bruker Elexsys E 580 (Germany). It was in the first established a significant increase in the sterol content under clinorotation. It is of much interest because sterols along with glyco- and phospholipids and mainly saturated fatty acids form “rafts” that are membrane certain domains, where a lipid bilayer is in the dense, highly ordered state. As rafts include the protein complexes, which are necessary for perception and transduction of exogenous signals, stress protection, pathogenesis, vesicular transport also, a significant increase of sterols under clinorotation may indicate the changes in both membrane permeability and protein activity. On the basis of obtained data, the future researches of components of signaling pathways and regulation of certain plasmalemma membranous proteins activity are grounded and planned.

Influences of two high intensity interval exercise protocols on the main determinants of blood fluidity in overweight men.

PubMed

Ahmadizad, Sajad; Bassami, Minoo; Hadian, Mohsen; Eslami, Maryam

2016-01-01

Acute effects of continuous exercise on the markers of blood fluidity have been addressed in different populations and the changes are intensity related. However, the effect of different high intensity interval exercise (HIIE) on these variables is unclear. This study is designed to determine the effects of two different HIIE with different work/rest ratios but the same energy expenditure on the main determinants of blood fluidity. Ten overweight men (age, 26.3±1.7 yrs) completed two HIIE protocols on two separate occasions with one week intervening. The two HIIE encompassed performing: 1) 6 intervals of 2 min activity at 85% of VO2max interspersed by 2 min active recovery at 30% of VO2max (ratio 1 to 1, HIIE1/1), and 2) 6 intervals of 30 s activity at 110% of VO2max interspersed by 4 min active recovery at 40% of VO2max (ratio 1 to 8, HIIE1/8). Each exercise trial was followed by 30 min rest. Venous blood samples were obtained before exercise, immediately after exercise and after recovery and analyzed for blood and plasma viscosity, fibrinogen and red blood cell indices. The HIIE1/1 protocol led to higher reduction (P < 0.01) in plasma volume changes compared to HIIE1/8 (9.9% vs 5.7%). Moreover, increases in blood viscosity, plasma viscosity, hematocrit, RBC count and mean arterial blood pressure observed following HIIE1/1 were significantly (P < 0.05) higher than HIIE1/8 ; whereas, the changes in fibrinogen concentration neither were significant in response to both trials nor were significantly different between two protocols (P > 0.05). However, the changes in all variables during exercise were transient and returned to the baseline levels after 30 min recovery. It is concluded that the HIIE protocol with lower intensity and shorter rest intervals (higher work to rest ratio) clearly results in more physiological strain than HIIE with higher intensity but longer rest intervals (lower work to rest ratio) in overweight individuals, and that the work to rest ratio could be as important as exercise intensity when considering the hemorheological variables during HIIE.

Cytoskeletal stiffness, friction, and fluidity of cancer cell lines with different metastatic potential.

PubMed

Coughlin, Mark F; Bielenberg, Diane R; Lenormand, Guillaume; Marinkovic, Marina; Waghorne, Carol G; Zetter, Bruce R; Fredberg, Jeffrey J

2013-03-01

We quantified mechanical properties of cancer cells differing in metastatic potential. These cells included normal and H-ras-transformed NIH3T3 fibroblast cells, normal and oncoprotein-overexpressing MCF10A breast cancer cells, and weakly and strongly metastatic cancer cell line pairs originating from human cancers of the skin (A375P and A375SM cells), kidney (SN12C and SN12PM6 cells), prostate (PC3M and PC3MLN4 cells), and bladder (253J and 253JB5 cells). Using magnetic twisting cytometry, cytoskeletal stiffness (g') and internal friction (g″) were measured over a wide frequency range. The dependencies of g' and g″ upon frequency were used to determine the power law exponent x which is a direct measure of cytoskeletal fluidity and quantifies where the cytoskeleton resides along the spectrum of solid-like (x = 1) to fluid-like (x = 2) states. Cytoskeletal fluidity x increased following transformation by H-ras oncogene expression in NIH3T3 cells, overexpression of ErbB2 and 14-3-3-ζ in MCF10A cells, and implantation and growth of PC3M and 253J cells in the prostate and bladder, respectively. Each of these perturbations that had previously been shown to enhance cancer cell motility and invasion are shown here to shift the cytoskeleton towards a more fluid-like state. In contrast, strongly metastatic A375SM and SN12PM6 cells that disseminate by lodging in the microcirculation of peripheral organs had smaller x than did their weakly metastatic cell line pairs A375P and SN12C, respectively. Thus, enhanced hematological dissemination was associated with decreased x and a shift towards a more solid-like cytoskeleton. Taken together, these results are consistent with the notion that adaptations known to enhance metastatic ability in cancer cell lines define a spectrum of fluid-like versus solid-like states, and the position of the cancer cell within this spectrum may be a determinant of cancer progression.

Plasma membrane microorganization of LR73 multidrug-resistant cells revealed by FCS

NASA Astrophysics Data System (ADS)

Winckler, Pascale; Jaffiol, Rodolphe; Cailler, Aurélie; Morjani, Hamid; Jeannesson, Pierre; Deturche, Régis

2011-03-01

Tumoral cells could present a multidrug resistance (MDR) to chemotherapeutic treatments. This drug resistance would be associated to biomechanisms occurring at the plasma membrane level, involving modification of membrane fluidity, drug permeability, presence of microdomains (rafts, caveolae...), and membrane proteins overexpression such as Pglycoprotein. Fluorescence correlation spectroscopy (FCS) is the relevant method to investigate locally the fluidity of biological membranes through the lateral diffusion of a fluorescent membrane probe. Thus, we use FCS to monitor the plasma membrane local organization of LR73 carcinoma cells and three derived multidrug-resistant cancer cells lines. Measurements were conducted at the single cell level, which enabled us to get a detailed overview of the plasma membrane microviscosity distribution of each cell line studied. Moreover, we propose 2D diffusion simulation based on a Monte Carlo model to investigate the membrane organisation in terms of microdomains. This simulation allows us to relate the differences in the fluidity distributions with microorganization changes in plasma membrane of MDR cells.

"It Has No Color, It Has No Gender, It's Gender Bending": Gender and Sexuality Fluidity and Subversiveness in Drag Performance.

PubMed

Egner, Justine; Maloney, Patricia

2016-07-01

Gender identity is a key question for drag performers. Previous research has shown a lack of consensus about the subversiveness and gender fluidity of drag performers. This article examines the question: How does the relationship between performers and their audience affect the subversive nature and gender representation of drag performers in this study? Furthermore, is this relationship complicated by sexuality? This study uses ethnographic and interview methods, examining experiences of 10 drag performers. Findings indicate mutuality in the relationship between performers and audience. The recursiveness of this relationship provides a constant feedback to the performers in their effort to displace the audience's previously held notions. The performers have fluid understandings of gender and sexuality, often presenting multiple genders in and out of drag. Interactions between performers and their audience indicate their belief in gender fluidity; moreover, the drag performers themselves desire to be subversive and gender and sexually fluid.

[The effects of electromagnetic pulse on fluidity and lipid peroxidation of mitochondrial membrane].

PubMed

Wang, Changzhen; Cong, Jianbo; Xian, Hong; Cao, Xiaozhe; Sun, Cunpu; Wu, Ke

2002-08-01

To study the effects of intense electromagnetic pulse(EMP) on the biological effects of mitochondrial membrane. Rat liver mitochondrial suspension was exposed to EMP at 60 kV/m level. The changes of membrane lipid fluidity and membrane protein mobility were detected by ESR and spin label technique. Malondialdehyde(MDA) was detected by spectrophotometer. The mobility of membrane protein decreased significantly(P < 0.05). Correlation time (tau c) of control group was (0.501 +/- 0.077) x 10(-9)s, and tau c of EMP group was (0.594 +/- 0.049) x 10(-9)s, indicating that the mobility of protein was restricted. The fluidity of mitochondrial membrane increased significantly(P < 0.05) at the same time. Order parameter(S) of mitochondrial membrane lipid in control group was 0.63 +/- 0.01, while S of EMP group was 0.61 +/- 0.01(P < 0.05). MDA decreased significantly. The mobility and lipid peroxidation of mitochondrial membrane may be disturbed after EMP exposure.

A calcium channel blocker, benidipine, improves cell membrane fluidity in human subjects via a nitric oxide-dependent mechanism. An electron paramagnetic resonance investigation.

PubMed

Tsuda, Kazushi; Nishio, Ichiro

2004-12-01

Recent studies have revealed that benidipine, a long-acting dihydropyridine-type of calcium (Ca) channel blocker, may exert its protective effect against vascular disorders by increasing nitric oxide (NO) production. The purpose of the present study was to investigate the effects of benidipine and NO on the membrane function in human subjects. We measured the membrane fluidity of erythrocytes by using an electron paramagnetic resonance (EPR) and spin-labeling method. Benidipine decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (h(o)/h(-1)) for 16-NS obtained from EPR spectra of erythrocyte membranes in a dose-dependent manner in normotensive volunteers. The finding indicated that benidipine increased the membrane fluidity and improved the microviscosity of erythrocytes. The effect of benidipine was significantly potentiated by the NO donor, S-nitroso-n-acetylpenicillamine, and by the cyclic guanosine 3', 5'-monophosphate (cGMP) analog, 8-bromo-cGMP. In contrast, the change evoked by benidipine was counteracted by the NO synthase inhibitors, N(G)-nitro-L-arginine-methyl-ester and asymmetric dimethyl-L-arginine. These results demonstrated that benidipine increased the membrane fluidity of erythrocytes, at least in part, via the NO- and cGMP-dependent mechanism. Furthermore, the data strongly suggest that benidipine might have a beneficial effect on the rheologic behavior of erythrocytes and the improvement of the microcirculation in humans.

Preparation and characterization of acorn starch/poly(lactic acid) composites modified with functionalized vegetable oil derivates.

PubMed

Li, Shouhai; Xia, Jianling; Xu, Yuzhi; Yang, Xuejuan; Mao, Wei; Huang, Kun

2016-05-20

Composites of acorn starch (AS) and poly(1actic acid) (PLA) modified with dimer fatty acid (DFA) or dimer fatty acid polyamide (DFAPA) were produced by a hot-melt extrusion method. The effects of DFA and DFAPA contents on the mechanical, hydrophobic, thermal properties and melt fluidity of the composites were studied under an invariable AS-to-PLA mass ratio of 40/60. SEM and DMA research results show that the compatibility of AS/PLA composites are determined by the dosage of DFA or DFAPA. The hydrophobicity and melt fluidity of composites are improved with the addition of DFA and DFAPA. The glass transition temperatures of the composites are all reduced remarkably by additives DFA and DFAPA. However, DFA and DFAPA exert different effects on the mechanical properties of AS/PLA composites. In the DFAPA-modified system, the tensile and flexural strength first increase and then decrease with the increase of DFAPA dosage; the mechanical strength is maximized when the dosage of DFAPA is 2 wt% of total weight. In the DFA-modified system, the tensile and flexural strength decrease with the increase of DFA dosage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stability of Sexual Attractions Across Different Timescales: The Roles of Bisexuality and Gender.

PubMed

Diamond, Lisa M; Dickenson, Janna A; Blair, Karen L

2017-01-01

We examined the stability of same-sex and other-sex attractions among 294 heterosexual, lesbian, gay, and bisexual men and women between the ages of 18 and 40 years. Participants used online daily diaries to report the intensity of each day's strongest same-sex and other-sex attraction, and they also reported on changes they recalled experiencing in their attractions since adolescence. We used multilevel dynamical systems models to examine individual differences in the stability of daily attractions (stability, in these models, denotes the tendency for attractions to "self-correct" toward a person-specific setpoint over time). Women's attractions showed less day-to-day stability than men's, consistent with the notion of female sexual fluidity (i.e., heightened erotic sensitivity to situational and contextual influences). Yet, women did not recollect larger post-adolescent changes in sexual attractions than did men, and larger recollected post-adolescent changes did not predict lower day-to-day stability in the sample as a whole. Bisexually attracted individuals recollected larger post-adolescent changes in their attractions, and they showed lower day-to-day stability in attractions to their "less-preferred" gender, compared to individuals with exclusive same-sex or exclusive other-sex attractions. Our results suggest that both gender and bisexuality have independent influences on sexual fluidity, but these influences vary across short versus long timescales, and they also differ for attractions to one's "more-preferred" versus "less-preferred" gender.

"None Must Meddle Betueene Man and Wife": assessing family and the fluidity of public and private in early modern Scotland.

PubMed

Nugent, Janay

2010-01-01

The physical and ideological boundaries between public and private in early modern Scotland were constantly contested, resulting in a shifting reality of what was public and private. This fluidity has been recognized by historians, but how, when, and why the shifting took place is not as clear. The moral church courts (Kirk Sessions) of Reformation Scotland allow a unique opportunity to begin to understand the largely elusive boundaries between public and private in the early modern era.

Advanced fuel system technology for utilizing broadened property aircraft fuels

NASA Technical Reports Server (NTRS)

Reck, G. M.

1980-01-01

Factors which will determine the future supply and cost of aviation turbine fuels are discussed. The most significant fuel properties of volatility, fluidity, composition, and thermal stability are discussed along with the boiling ranges of gasoline, naphtha jet fuels, kerosene, and diesel oil. Tests were made to simulate the low temperature of an aircraft fuel tank to determine fuel tank temperatures for a 9100-km flight with and without fuel heating; the effect of N content in oil-shale derived fuels on the Jet Fuel Thermal Oxidation Tester breakpoint temperature was measured. Finally, compatibility of non-metallic gaskets, sealants, and coatings with increased aromatic content jet fuels was examined.

High Cholesterol/Low Cholesterol: Effects in Biological Membranes: A Review.

PubMed

Subczynski, Witold K; Pasenkiewicz-Gierula, Marta; Widomska, Justyna; Mainali, Laxman; Raguz, Marija

2017-12-01

Lipid composition determines membrane properties, and cholesterol plays a major role in this determination as it regulates membrane fluidity and permeability, as well as induces the formation of coexisting phases and domains in the membrane. Biological membranes display a very diverse lipid composition, the lateral organization of which plays a crucial role in regulating a variety of membrane functions. We hypothesize that, during biological evolution, membranes with a particular cholesterol content were selected to perform certain functions in the cells of eukaryotic organisms. In this review, we discuss the major membrane properties induced by cholesterol, and their relationship to certain membrane functions.

Plastic wastes as modifiers of the thermoplasticity of coal

DOE Office of Scientific and Technical Information (OSTI.GOV)

M.A. Diez; C. Barriocanal; R. Alvarez

2005-12-01

Plastic waste recycling represents a major challenge in environmental protection with different routes now available for dealing with mechanical, chemical, and energy recycling. New concepts in plastic waste recycling have emerged so that now such wastes can be used to replace fossil fuels, either as an energy source or as a secondary raw material. Our objective is to explore the modification of the thermoplastic properties of coal in order to assess the possibility of adding plastic waste to coal for the production of metallurgical coke. Two bituminous coals of different rank and thermoplastic properties were used as a base componentmore » of blends with plastic wastes such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET), and acrilonitrile-butadiene-styrene copolymer (ABS). In all cases, the addition of plastic waste led to a reduction in Gieseler maximum fluidity, the extent of the reduction depending on the fluidity of the base coal, and the amount, the molecular structure, and the thermal behavior of the polymer. As a consequence, the amount of volatile matter released by the plastic waste before, during, and after the maximum fluidity of the coal and the hydrogen-donor and hydrogen-acceptor capacities of the polymer were concluded to be key factors in influencing the extent of the reduction in fluidity and the development of anisotropic carbons. The incorporation of the plastic to the carbon matrix was clearly established in semicokes produced from blends of a high-fluid coal and the plastic tested by SEM examination. 42 refs., 10 figs., 7 tabs.« less

Numerical analysis of temperature field in the high speed rotary dry-milling process

NASA Astrophysics Data System (ADS)

Wu, N. X.; Deng, L. J.; Liao, D. H.

2018-01-01

For the effect of the temperature field in the ceramic dry granulation. Based on the Euler-Euler mathematical model, at the same time, made ceramic dry granulation experiment equipment more simplify and established physical model, the temperature of the dry granulation process was simulated with the granulation time. The relationship between the granulation temperature and granulation effect in dry granulation process was analyzed, at the same time, the correctness of numerical simulation was verified by measuring the fluidity index of ceramic bodies. Numerical simulation and experimental results showed that when granulation time was 4min, 5min, 6min, maximum temperature inside the granulation chamber was: 70°C, 85°C, 95°C. And the equilibrium of the temperature in the granulation chamber was weakened, the fluidity index of the billet particles was: 56.4. 89.7. 81.6. Results of the research showed that when granulation time was 5min, the granulation effect was best. When the granulation chamber temperature was more than 85°C, the fluidity index and the effective particles quantity of the billet particles were reduced.

Interaction of cationic carbosilane dendrimers and their complexes with siRNA with erythrocytes and red blood cell ghosts.

PubMed

Wrobel, Dominika; Kolanowska, Katarzyna; Gajek, Arkadiusz; Gomez-Ramirez, Rafael; de la Mata, Javier; Pedziwiatr-Werbicka, Elżbieta; Klajnert, Barbara; Waczulikova, Iveta; Bryszewska, Maria

2014-03-01

We have investigated the interactions between cationic NN16 and BDBR0011 carbosilane dendrimers with red blood cells or their cell membranes. The carbosilane dendrimers used possess 16 cationic functional groups. Both the dendrimers are made of water-stable carbon-silicon bonds, but NN16 possesses some oxygen-silicon bonds that are unstable in water. The nucleic acid used in the experiments was targeted against GAG-1 gene from the human immunodeficiency virus, HIV-1. By binding to the outer leaflet of the membrane, carbosilane dendrimers decreased the fluidity of the hydrophilic part of the membrane but increased the fluidity of the hydrophobic interior. They induced hemolysis, but did not change the morphology of the cells. Increasing concentrations of dendrimers induced erythrocyte aggregation. Binding of short interfering ribonucleic acid (siRNA) to a dendrimer molecule decreased the availability of cationic groups and diminished their cytotoxicity. siRNA-dendrimer complexes changed neither the fluidity of biological membranes nor caused cell hemolysis. Addition of dendriplexes to red blood cell suspension induced echinocyte formation. Copyright © 2013 Elsevier B.V. All rights reserved.

Optimization and characterization of liposome formulation by mixture design.

PubMed

Maherani, Behnoush; Arab-tehrany, Elmira; Kheirolomoom, Azadeh; Reshetov, Vadzim; Stebe, Marie José; Linder, Michel

2012-02-07

This study presents the application of the mixture design technique to develop an optimal liposome formulation by using the different lipids in type and percentage (DOPC, POPC and DPPC) in liposome composition. Ten lipid mixtures were generated by the simplex-centroid design technique and liposomes were prepared by the extrusion method. Liposomes were characterized with respect to size, phase transition temperature, ζ-potential, lamellarity, fluidity and efficiency in loading calcein. The results were then applied to estimate the coefficients of mixture design model and to find the optimal lipid composition with improved entrapment efficiency, size, transition temperature, fluidity and ζ-potential of liposomes. The response optimization of experiments was the liposome formulation with DOPC: 46%, POPC: 12% and DPPC: 42%. The optimal liposome formulation had an average diameter of 127.5 nm, a phase-transition temperature of 11.43 °C, a ζ-potential of -7.24 mV, fluidity (1/P)(TMA-DPH)((¬)) value of 2.87 and an encapsulation efficiency of 20.24%. The experimental results of characterization of optimal liposome formulation were in good agreement with those predicted by the mixture design technique.

In vivo influence of extract from Aronia melanocarpa on the erythrocyte membranes in patients with hypercholesterolemia.

PubMed

Duchnowicz, Piotr; Nowicka, Agmieszka; Koter-Michalak, Maria; Broncel, Marlena

2012-09-01

Hypercholesterolemia increases cholesterol concentration in erythrocyte membranes, which results in decrease of membrane fluidity and decreases the deformability of red blood cells. The fruits of Arona melanocarpa contains many of polyphenols and other compounds that have beneficial health effects. The aim of the study was to estimate the influence of 2-month supplementation of extract from Aronia melanocarpa (100 mg Aronox, three times per day) on cholesterol concentration, lipid peroxidation, membrane fluidity, level of thiol groups and activity of ATPase in erythrocytes from patients with hypercholesterolemia. The study involved 25 patients with hypercholesterolemia without pharmacological treatment and 20 healthy individuals as a control group. Blood samples were collected before, and after 1 and 2 months of Aronia administration. The 2-month Aronia supplementation resulted in a decrease of cholesterol concentration (by 22%) and a decrease of lipid peroxidation (by 40%), and an increase of membrane fluidity. No statistically significant increase of the concentration of thiol groups and of ATPase activity were observed. Our study shows that supplementation of extract from Aronia melanocarpa has a beneficial effect on rheological properties of erythrocytes.

[Status of vitamin A, vitamin B2, iron and an-oxidantive activity in anemic pregnant women in China].

PubMed

Yang, Fang; Ma, Ai-Guo; Zhang, Xiu-Zhen; Jiang, Dian-Chen

2006-05-01

To investigate the status of vitamin A(VA), vitamin B2 (VB2), iron and anoxidative function in anemic and non-anemic pregnant women. 426 anemic and 36 non-anemic pregnant women were included in the study. The survey of 24-hour's diet recall of pregnant women was made to evaluate intake of iron, VB2, folic acid, etc by the nutrition software provided by Beijing 301 hospital, iron and VA were measured by Radioimmunoassay (RIA) and by high-pressure liquid chromatography. VB2 status was detected using the assay for erythrocyte glutathione reductase (Egr; EC 1.6.4.2) activity. SOD and GSH-Px activities and MDA were determined using commercial kits. Peripheral blood erythrocyte membrane fluidity was detected by using 1,6-diphenyl-1,3,5-hexatriene as a probe, the degree of fluorescence polarization (P) at 25 degrees C of disrupted cells plasma membranes were compared for a variety of systems. Median intakes of protein and vitamin C met the current Chinese RNIs for pregnancy, whereas intakes of(VA) and VB2 were well below the recommendations. Intake of iron were above 90%, but the main sources of iron are vegetables. Plasma VA (1.25 micromol/L) and iron (20.57 microg/L) were lower, BGRAC (1.79) was higher than that in non-anemia group (VA 1.57 micromol/L, SF 33.16 microg/L, BGRAC 1.52). The level of plasma SOD (77.1U/ml) and the activity of GSH-Px (61.9U) were lower than those in non-anemia group (92.2U/ml, 71.6U, P < 0.05), while MDA (4.58 nmol/ml) level and erythrocyte membrane (P = 0.2622, eta = 2.7465) fluidity were higher than those non-anemia group(MDA = 3.78 nmol/ ml, P = 0.2360, eta = 2.3658). Plasam VA, VB2 and iron, antioxidantcapacity and erythrocyte membrane fluidity were decreased in the anemic pregnant women.

Changes in lipid fluidity and fatty acid composition with altered culture temperature in Tetrahymena pyriformis-NT1.

PubMed

Connolly, J G; Brown, I D; Lee, A G; Kerkut, G A

1985-01-01

Cultures of T. pyriformis-NT1 were grown at 20 degrees C (Tg 20 degrees C) and 38 degrees C (Tg 38 degrees C). G.L.C. analysis and D.P.H. fluorescence polarization measurements in extracted phospholipids indicated that there was increased saturation of fatty acids and relatively reduced fluidity as growth temperature was increased. Breakpoints occurred in the Arrhenius plots of fluorescence polarization at 16 degrees C for Tg 38 degrees C total extracted phospholipids and 9 degrees C for Tg 20 degrees C lipids.

Retardation effect of different alcohols on the cement coagulation in polycarboxylate- and naphthalene-based cement admixtures

NASA Astrophysics Data System (ADS)

Huang, S. M.; Zhou, F. L.

2017-12-01

Alcohol has great potential to delay the coagulation of cement. The effects of alcohol on paste fluidity and normal consistency coagulation time have been studied for polycarboxylate superplasticizer and naphthene cement admixture. Seven alcohols were combined with polycarboxylate superplasticizer and naphthene at a concentration of 0.01-0.09%, respectively, including n-propanol, methanol, sorbitol, ethylene glycol, glycerol, ethanol, and mannitol. The fluidity and normal consistency coagulation time of each cement admixture were measured. The performance of both polycarboxylate superplasticizer and naphthene cement admixtures were compared to develop cement admixture with delayed coagulation.

Influence of selenium and fluoride on blood antioxidant capacity of rats.

PubMed

Feng, Pei; Wei, Jun-ren; Zhang, Zi-gui

2012-09-01

This study is to explore the effect of selenium and fluoride on blood antioxidant capacity of rats, and try to find out the optimal level of selenium in drinking water against fluorosis. Animals were divided into control group, sodium fluoride treated group (NaF, 50 mg/L) and selenium+NaF treated group (sodium selenite 0.375, 0.75, 1.5 mg/L) in water were respectively administered to male rats, which were decapitated after 6 months. Their blood was collected for GSH-Px activity, plasma SOD activity, T-AOC assay, uric acid assay, sialic acid (SA) content and MDA content, and the fluidity of erythrocyte membrane by electron spin resonance (ESR) was analyzed. The results showed that, compared with the control group, the blood antioxidant capacity of the rats exposed to fluoride was down-regulated significantly (P<0.05, P<0.01), MDA content increased significantly (P<0.05), the fluidity of erythrocyte membrane decreased (P<0.05, P<0.01). Meanwhile, the treatments of selenium along with NaF compared with fluorosis group, SOD activity, GSH-Px activity and T-AOC assay increased respectively, MDA content decreased significantly (P<0.05) in NaF+Se (Se 0.75, 1.5 mg/L) treated groups, uric acid level was up-regulated, but had no statistical significant difference (P>0.05). The fluidity of erythrocyte membrane showed significant increase (P<0.05), the content of SA was lower. Fluorosis could induce the decline of blood antioxidant capacity and the fluidity of erythrocyte membrane, as evident in this study, and Se at different levels possess some antagonistic effects on blood induced by fluoride. However, high dose of selenium (1.5 mg/L) is the optimum concentration. Copyright © 2010 Elsevier GmbH. All rights reserved.

Vitamin E supplementation protects erythrocyte membranes from oxidative stress in healthy Chinese middle-aged and elderly people.

PubMed

Sun, Yongye; Ma, Aiguo; Li, Yong; Han, Xiuxia; Wang, Qiuzhen; Liang, Hui

2012-05-01

Elderly people are subject to higher levels of oxidative stress than are young people. Vitamin E, as a powerful antioxidant residing mainly in biomembranes, may provide effective protection against oxidative membrane damage and resultant age-related deterioration, especially in the elderly. We hypothesized that appropriate levels of vitamin E supplementation would protect erythrocyte membranes from oxidative stress and thus improve membrane fluidity in healthy middle-aged and elderly people. To test this, we conducted a 4-month double-blind, randomized trial in which 180 healthy subjects (55-70 years old) were randomly divided into 4 groups: group C (control), and 3 treatment groups in which daily doses of 100 mg (VE1), 200 mg (VE2), and 300 mg (VE3) dl-α-tocopheryl acetate were administered. We measured plasma α-tocopherol concentration, malondialdehyde, and superoxide dismutase levels, erythrocyte hemolysis, and erythrocyte membrane fluidity at the beginning and end of the trial. After 4 months supplementation, plasma α-tocopherol concentrations in the 3 treatment groups had increased by 71%, 78%, and 95%, respectively (all P < .01), and significant decreases in plasma malondialdehyde concentrations were observed in these groups (all P < .05). Erythrocyte hemolysis was decreased by 20% to 38% after vitamin E supplementation (all P < .05), and in addition, groups VE2 and VE3 showed dramatic improvements in erythrocyte membrane fluidity (P < .01). Surprisingly, superoxide dismutase activity also decreased significantly in the treatment groups (all P < .05). In summary, vitamin E supplementation apparently alleviates oxidative stress in healthy middle-aged to elderly people, at least in part by improving erythrocyte membrane fluidity and reducing erythrocyte hemolysis. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of various enhancers on transdermal penetration of indomethacin and urea, and relationship between penetration parameters and enhancement factors.

PubMed

Ogiso, T; Iwaki, M; Paku, T

1995-04-01

The enhancing capacity of various chemicals, which are widely recognized as enhancers, for the transdermal penetration into full-thickness rat skin of a model lipophilic drug [indomethacin (IND)] and a hydrophilic permeant (urea) was estimated by an in vitro technique. In addition, the fluidity of the stratum corneum lipids, the partitioning of IND into skin, the lipid (ceramides) extraction from the stratum corneum by enhancers, and the IND solubility in enhancer vehicle were measured and related to the enhancing capacity. In vitro permeation experiments with hairless rat skin unequivocally revealed that the enhancers varied in abilities to enhance the fluxes of both agents. Laurocapram, isopropylmyristate (IPM), sodium oleate, and cineol increased fluxes of both agents to a great extent, but N-methyl-2-pyrrolidone (NMP), N,N-diethyl-m-tolamide (DEET), and oleyl oleate were less effective acclerants. Many enhancers increased the fluidity of the lipids [with a threshold of approximately 0.6-0.8 ns at 37 degrees C in the rotational correlation time (tau c)], the skin partitioning of IND, the extraction of ceramides from the cornified cells, and the thermodynamic activity of IND in vehicle (calculated from the solubility) to varying extents. A good correlation was observed between the increase in the fluidity of stratum corneum lipids and the partitioning of IND into skin, between the increase in the fluidity and the flux or the decrease in lag time for IND, between the removal of ceramides and the skin partitioning of IND, and between the removal of ceramides and the flux of urea (p < 0.05 in all cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of polyunsaturated fatty acids with the cold adaptation of Rhodotorula glutinis.

PubMed

He, Jing; Yang, Zhaojie; Hu, Binbin; Ji, Xiuling; Wei, Yunlin; Lin, Lianbing; Zhang, Qi

2015-11-01

This study aimed to investigate the correlation between the cold adaptation of Rhodotorula glutinis YM25079 and the membrane fluidity, content of polyunsaturated fatty acids and mRNA expression level of the Δ(12)-desaturase gene. The optimum temperature for YM25079 growth was analysed first, then the composition changes of membrane lipid in YM25079 were detected by GC-MS and membrane fluidity was evaluated by 1-anilinonaphthalene-8-sulphonate (ANS) fluorescence. Meanwhile, the encoding sequence of Δ(12)-fatty acid desaturase in YM25079 was cloned and further transformed into Saccharomyces cerevisiae INVScl for functional analysis. The mRNA expression levels of Δ(12)-fatty acid desaturase at 15°C and 25°C were analysed by real-time PCR. YM25079 could grow at 5-30°C, with the optimum temperature of 15°C. The membrane fluidity of YM25079 was not significantly reduced when the culture temperature decreased from 25°C to 15°C, but the content of polyunsaturated fatty acids (PUFAs), including linoleic acid and α-Linolenic acid increased significantly from 29.4% to 55.39%. Furthermore, a novel Δ(12)-fatty acid desaturase gene YM25079RGD12 from YM25079 was successfully identified and characterized, and the mRNA transcription level of the Δ(12)-desaturase gene was about five-fold higher in YM25079 cells grown at 15°C than that at 25°C. These results suggests that the cold adaptation of Rhodotorula glutinis YM25079 might result from higher expression of genes, especially the Δ(12)-fatty acid desaturase gene, during polyunsaturated fatty acids biosynthesis, which increased the content of PUFAs in the cell membrane and maintained the membrane fluidity at low temperature. Copyright © 2015 John Wiley & Sons, Ltd.

Molecular view of the interaction between iota-carrageenan and a phospholipid film and its role in enzyme immobilization.

PubMed

Nobre, Thatyane M; de Sousa e Silva, Heurison; Furriel, Rosa P M; Leone, Francisco A; Miranda, Paulo B; Zaniquelli, Maria Elisabete D

2009-05-28

Proteins incorporated into phospholipid Langmuir-Blodgett (LB) films are a good model system for biomembranes and enzyme immobilization studies. The specific fluidity of biomembranes, an important requisite for enzymatic activity, is naturally controlled by varying phospholipid compositions. In a model system, instead, LB film fluidity may be varied by covering the top layer with different substances able to interact simultaneously with the phospholipid and the protein to be immobilized. In this study, we immobilized a carbohydrate rich Neurospora crassa alkaline phosphatase (NCAP) in monolayers of the sodium salt of dihexadecylphosphoric acid (DHP), a synthetic phospholipid that provides very condensed Langmuir films. The binding of NCAP to DHP Langmuir-Blodgett (LB) films was mediated by the anionic polysaccharide iota-carrageenan (iota-car). Combining results from surface isotherms and the quartz crystal microbalance technique, we concluded that the polysaccharide was essential to promote the interaction between DHP and NCAP and also to increase the fluidity of the film. An estimate of DHP:iota-car ratio within the film also revealed that the polysaccharide binds to DHP LB film in an extended conformation. Furthermore, the investigation of the polysaccharide conformation at molecular level, using sum-frequency vibrational spectroscopy (SFG), indicated a preferential conformation of the carrageenan molecules with the sulfate groups oriented toward the phospholipid monolayer, and both the hydroxyl and ether groups interacting preferentially with the protein. These results demonstrate how interfacial electric fields can reorient and induce conformational changes in macromolecules, which may significantly affect intermolecular interactions at interfaces. This detailed knowledge of the interaction mechanism between the enzyme and the LB film is relevant to design strategies for enzyme immobilization when orientation and fluidity properties of the film provided by the matrix are important to improve enzymatic activity.

Cholesterol-loaded-cyclodextrins improve the post-thaw quality of stallion sperm.

PubMed

Murphy, C; English, A M; Holden, S A; Fair, S

2014-03-01

An unacceptable proportion of stallion sperm do not survive the freeze-thaw process. The hypothesis of this study was that adding cholesterol to a stallion semen extender would stabilise the sperm membrane, resulting in an improved post-thaw semen quality in terms of increased sperm viability, membrane integrity and fluidity, and reduced oxidative stress. Semen was collected from three stallions and diluted in four extenders: TALP; TALP+0.75mg methyl-β-cyclodextrin-cholesterol (MβCD)/mL (MβCD0.75); TALP+1.5mg MβCD-cholesterol/mL (MβCD1.5); and Equipro. Following 15min incubation, samples were centrifuged and diluted to 100×10(6)sperm/mL, frozen in 0.5mL straws and stored in liquid nitrogen. Sperm from each treatment was assessed for progressive linear motility (PLM) and acceptable membrane integrity under hypotonic conditions on a phase contrast microscope at 1000× while viability, membrane fluidity and superoxide generation were assessed by flow cytometry. The MβCD1.5 and MβCD0.75 treatments had a greater proportion of viable sperm than the TALP treatment (P<0.01). There was no effect of treatment on PLM or membrane integrity. The MβCD1.5 treatment had a greater proportion of viable sperm positive for membrane fluidity than the TALP treatment (P<0.05). The MβCD1.5 and MβCD0.75 treatments had a lesser proportion of viable sperm positive for superoxide generation than the TALP treatment (P<0.001). This study has demonstrated that adding cholesterol to stallion sperm prior to cryopreservation increases post-thaw viability, with these viable sperm being of better quality in terms of increased membrane fluidity and reduced superoxide generation. Copyright © 2014 Elsevier B.V. All rights reserved.

Eicosapentaenoic acid reduces membrane fluidity, inhibits cholesterol domain formation, and normalizes bilayer width in atherosclerotic-like model membranes.

PubMed

Mason, R Preston; Jacob, Robert F; Shrivastava, Sandeep; Sherratt, Samuel C R; Chattopadhyay, Amitabha

2016-12-01

Cholesterol crystalline domains characterize atherosclerotic membranes, altering vascular signaling and function. Omega-3 fatty acids reduce membrane lipid peroxidation and subsequent cholesterol domain formation. We evaluated non-peroxidation-mediated effects of eicosapentaenoic acid (EPA), other TG-lowering agents, docosahexaenoic acid (DHA), and other long-chain fatty acids on membrane fluidity, bilayer width, and cholesterol domain formation in model membranes. In membranes prepared at 1.5:1 cholesterol-to-phospholipid (C/P) mole ratio (creating pre-existing domains), EPA, glycyrrhizin, arachidonic acid, and alpha linolenic acid promoted the greatest reductions in cholesterol domains (by 65.5%, 54.9%, 46.8%, and 45.2%, respectively) compared to controls; other treatments had modest effects. EPA effects on cholesterol domain formation were dose-dependent. In membranes with 1:1 C/P (predisposing domain formation), DHA, but not EPA, dose-dependently increased membrane fluidity. DHA also induced cholesterol domain formation without affecting temperature-induced changes in-bilayer unit cell periodicity relative to controls (d-space; 57Å-55Å over 15-30°C). Together, these data suggest simultaneous formation of distinct cholesterol-rich ordered domains and cholesterol-poor disordered domains in the presence of DHA. By contrast, EPA had no effect on cholesterol domain formation and produced larger d-space values relative to controls (60Å-57Å; p<0.05) over the same temperature range, suggesting a more uniform maintenance of lipid dynamics despite the presence of cholesterol. These data indicate that EPA and DHA had different effects on membrane bilayer width, membrane fluidity, and cholesterol crystalline domain formation; suggesting omega-3 fatty acids with differing chain length or unsaturation may differentially influence membrane lipid dynamics and structural organization as a result of distinct phospholipid/sterol interactions. Copyright © 2016. Published by Elsevier B.V.

Properties of Plasma Membrane from Pea Root Seedlings under Altered Gravity

NASA Astrophysics Data System (ADS)

Klymchuk, D.; Baranenko, V.; Vorobyova, T. V.; Kurylenko, I.; Chyzhykova, O.; Dubovoy, V.

In this study, the properties of pea (Pisum sativum L.) plasma membrane were examined to determine how the membrane structure and functions are regulated in response to clinorotation (2 rev/min) conditions. Membrane preparations enriched by plasma membrane vesicles were obtained by aqueous two-phase partitioning from 6-day seedling roots. The specific characteristics of H^+-ATPase, lípid composition and peroxidation intensity as well as fluidity of lipid bilayer were analysed. ATP hydrolytic activity was inhibited by ortovanadate and was insensitive to aside and nitrate in sealed plasma membrane vesicles isolated from both clinorotated and control seedlings. Plasma membrane vesicles from clinorotated seedlings in comparison to controls were characterised by increase in the total lipid/protein ratio, ATP hydrolytic activity and intensifying of lipid peroxidation. Sitosterol and campesterol were the predominant free sterol species. Clinorotated seedlings contained a slightly higher level of unsaturated fatty acid than controls. Plasma membrane vesicles were labelled with pyrene and fluorescence originating from monomeric (I_M) molecules and excimeric (I_E) aggregates were measured. The calculated I_E/I_M values were higher in clinorotated seedlings compared with controls reflecting the reduction in membrane microviscosity. The involvement of the changes in plasma membrane lipid content and composition, fluidity and H^+-ATPase activity in response of pea seedlings to altered gravity is discussed.

Influence of different surfactants on the physicochemical properties of elastic liposomes.

PubMed

Barbosa, R M; Severino, P; Preté, P S C; Santana, M H A

2017-05-01

Elastic liposomes are capable to improve drug transport through the skin by acting as penetration enhancers due to the high fluidity and elasticity of the liposome membranes. Therefore, elastic liposomes were prepared and characterized to facilitate the transdermal transport of bioactive molecules. Liposomes consisted of dimyristoylphosphatidylcholine (DMPC) as the structural component, with different surfactants derived from lauric acid as elastic components: C 12 E 5 (polyoxyethylene-5-lauryl ether), PEG4L (polyethyleneglycol-4-lauryl ester), PEG4DL (polyethylene glycol-4-dilauryl ester), PEG8L (polyethylene glycol-8-lauryl ester) and PEG8DL (polyethylene glycol-8-dilauryl ester). The elastic liposomes were characterized in terms of their phospholipid content, mean diameter, size distribution, elasticity and stability during storage, as well as their ability to incorporate surfactant and permeate through 50 nm pore size membranes. The results showed that the phospholipid phase transition temperature, the fluidity of the lipid bilayer resulting from incorporation of the surfactant and the preservation of particle integrity were factors determining the performance of the elastic liposomes in permeating through nanoporous membranes. The best results were obtained using DMPC combined with the surfactants PEG8L or PEG8DL. The findings demonstrate the potential of using elastic liposomes for transdermal administration of drugs.

Agarose Gel Electrophoresis Reveals Structural Fluidity of a Phage T3 DNA Packaging Intermediate

PubMed Central

Serwer, Philip; Wright, Elena T.

2012-01-01

We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (1) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for stabilization of structure and then (2) determining of effective radius by two-dimensional agarose gel electrophoresis (2d-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2d-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging. PMID:22222979

Service climate as a mediator of organizational empowerment in customer-service employees.

PubMed

Mendoza-Sierra, Maria Isabel; Orgambídez-Ramos, Alejandro; Carrasco-González, Ana María; León-Jariego, José Carlos

2014-01-01

The aim of this study is to examine the mediating role of the service climate between organizational empowerment (i.e., dynamic structural framework, control of workplace decisions, fluidity in information sharing) and service quality (functional and relational). 428 contact employees from 46 hotels participated in the survey. Correlations demonstrated that dynamic structural framework, control decisions, and fluidity in information sharing are related to both functional and relational service quality. Regression analyses and Sobel tests revealed that service climate totally mediated the relationship between all three dimensions of organizational empowerment and relational service quality. Implications for practice and future research are discussed.

Effect of Morinda citrifolia fruit extract and its iridoid glycosides on blood fluidity.

PubMed

Murata, Kazuya; Abe, Yumi; Futamura-Masuda, Megumi; Uwaya, Akemi; Isami, Fumiyuki; Deng, Shixin; Matsuda, Hideaki

2014-07-01

The aim of this study was to investigate the effect of Morinda citrifolia fruit on blood fluidity. M. citrifolia fruit extract (MCF-ext) was investigated for its influence on blood aggregation and fibrinolysis. MCF-ext inhibited polybrene-induced erythrocyte aggregation and thrombin activity. The fibrinolytic activity of MCF-ext, in the euglobulin lysis time test and fibrin plate assay, is reported here for the first time. One of the active compounds was an iridoid glycoside, asperulosidic acid. The results indicated that MCF-ext is a potentially useful health food which is capable of improving blood flow and preventing lifestyle-related diseases.

The fluidity of Thai women's gendered and sexual subjectivities.

PubMed

Thaweesit, Suchada

2004-05-01

This paper reports on an ethnographic study of gender and sexuality as factors within contemporary Thai factory women's subjectivities. Competing discourses of what it means to be a woman in contemporary Thai society make women's self-presentations fluid and incoherent. Data from participant-observation and open-ended interviews suggest that the fluidity and inconsistency of women's self-presentations reflect both their negative experiences and oppression within the Thai patriarchal system, and women's strength and resistance to the normative discourses that oppress them. By naming or reinterpreting experiences and desires in their own terms, Thai factory women can redraw elements of their own lives.

Describing Temperature-Dependent Self-Diffusion Coefficients and Fluidity of 1- and 3-Alcohols with the Compensated Arrhenius Formalism.

PubMed

Fleshman, Allison M; Forsythe, Grant E; Petrowsky, Matt; Frech, Roger

2016-09-22

The location of the hydroxyl group in monohydroxy alcohols greatly affects the temperature dependence of the liquid structure due to hydrogen bonding. Temperature-dependent self-diffusion coefficients, fluidity (the inverse of viscosity), dielectric constant, and density have been measured for several 1-alcohols and 3-alcohols with varying alkyl chain lengths. The data are modeled using the compensated Arrhenius formalism (CAF). The CAF follows a modified transition state theory using an Arrhenius-like expression to describe the transport property, which consists of a Boltzmann factor containing an energy of activation, Ea, and an exponential prefactor containing the temperature-dependent solution dielectric constant, εs(T). Both 1- and 3-alcohols show the Ea of diffusion coefficients (approximately 43 kJ mol(-1)) is higher than the Ea of fluidity (approximately 35 kJ mol(-1)). The temperature dependence of the exponential prefactor in these associated liquids is explained using the dielectric constant and the Kirkwood-Frölich correlation factor, gk. It is argued that the dielectric constant must be used to account for the additional temperature dependence due to variations in the liquid structure (e.g., hydrogen bonding) for the CAF to accurately model the transport property.

Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence

PubMed Central

Sandor, Roman; Der, Christophe; Grosjean, Kevin; Anca, Iulia; Noirot, Elodie; Leborgne-Castel, Nathalie; Lochman, Jan; Simon-Plas, Françoise; Gerbeau-Pissot, Patricia

2016-01-01

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence. PMID:27604805

Effects of TEA·HCl hardening accelerator on the workability of cement-based materials

NASA Astrophysics Data System (ADS)

Pan, Wenhao; Ding, Zhaoyang; Chen, Yanwen

2017-03-01

The aim of the test is to research the influence rules of TEA·HCl on the workability of cement paste and concrete. Based on the features of the new hardening accelerator, an experimental analysis system were established through different dosages of hardening accelerator, and the feasibility of such accelerator to satisfy the need of practical engineering was verified. The results show that adding of the hardening accelerator can accelerate the cement hydration, and what’s more, when the dosage was 0.04%, the setting time was the shortest while the initial setting time and final setting time were 130 min and 180 min, respectively. The initial fluidity of cement paste of adding accelerator was roughly equivalent compared with that of blank. After 30 min, fluidity loss would decrease with the dosage increasing, but fluidity may increase. The application of the hardening accelerator can make the early workability of concrete enhance, especially the slump loss of 30 min can improve more significantly. The bleeding rate of concrete significantly decreases after adding TEA·HCl. The conclusion is that the new hardening accelerator can meet the need of the workability of cement-based materials in the optimum dosage range.

The effect of MLS laser radiation on cell lipid membrane.

PubMed

Pasternak, Kamila; Wróbel, Dominika; Nowacka, Olga; Pieszyński, Ireneusz; Bryszewska, Maria; Kujawa, Jolanta

2018-03-14

Authors of numerous publications have proved the therapeutic effect of laser irradiation on biological material, but the mechanisms at cellular and subcellular level are not yet well understood. The aim of this study was to assess the effect of laser radiation emitted by the MLS M1 system (Multiwave Locked System) at two wavelengths (808 nm continuous and 905 nm pulsed) on the stability and fluidity of liposomes with a lipid composition similar to that of human erythrocyte membrane or made of phosphatidylocholine. Liposomes were exposed to low-energy laser radiation at surface densities 195 mW/cm² (frequency 1,000 Hz) and 230 mW/cm² (frequency 2,000 Hz). Different doses of radiation energy in the range 0-15 J were applied. The surface energy density was within the range 0.46 - 4.9 J/cm ². The fluidity and stability of liposomes subjected to such irradiation changed depending on the parameters of radiation used. Since MLS M1 laser radiation, depending on the parameters used, affects fluidity and stability of liposomes with the lipid content similar to erythrocyte membrane, it may also cause structural and functional changes in cell membranes.

In vivo influence of extract from Aronia melanocarpa on the erythrocyte membranes in patients with hypercholesterolemia

PubMed Central

Duchnowicz, Piotr; Nowicka, Agnieszka; Koter-Michalak, Maria; Broncel, Marlena

2012-01-01

Summary Background Hypercholesterolemia increases cholesterol concentration in erythrocyte membranes, which results in decrease of membrane fluidity and decreases the deformability of red blood cells. The fruits of Arona melanocarpa contains many of polyphenols and other compounds that have beneficial health effects. Material/Methods The aim of the study was to estimate the influence of 2-month supplementation of extract from Aronia melanocarpa (100 mg Aronox, three times per day) on cholesterol concentration, lipid peroxidation, membrane fluidity, level of thiol groups and activity of ATPase in erythrocytes from patients with hypercholesterolemia. The study involved 25 patients with hypercholesterolemia without pharmacological treatment and 20 healthy individuals as a control group. Blood samples were collected before, and after 1 and 2 months of Aronia administration. Results The 2-month Aronia supplementation resulted in a decrease of cholesterol concentration (by 22%) and a decrease of lipid peroxidation (by 40%), and an increase of membrane fluidity. No statistically significant increase of the concentration of thiol groups and of ATPase activity were observed. Conclusions Our study shows that supplementation of extract from Aronia melanocarpa has a beneficial effect on rheological properties of erythrocytes. PMID:22936193

Hyperforin modifies neuronal membrane properties in vivo.

PubMed

Eckert, Gunter P; Keller, Jan-Henning; Jourdan, Claudia; Karas, Michael; Volmer, Dietrich A; Schubert-Zsilavecz, Manfred; Müller, Walter E

2004-09-02

Hyperforin, the major active constituent of St. John Wort (SJW) extract, affects several neurotransmitter systems in the brain putatively by modulation of the physical state of neuronal membranes. Accordingly, we tested the effects of SJW extract and of hyperforin on the properties of murine brain membrane fluidity. Oral administration of SJW extract and of hyperforin sodium salt results in significant hyperforin brain levels. Treatment of mice with hyperforin leads to decreased annular- and bulk fluidity and increased acyl-chain flexibility of brain membranes. All hyperforin related changes of membrane properties were significantly correlated with the corresponding hyperforin brain levels. Our data emphasises a membrane interaction of hyperforin that possibly contributes to its pharmacological effects.

Effects of Coal Gangue on Cement Grouting Material Properties

NASA Astrophysics Data System (ADS)

Liu, J. Y.; Chen, H. X.

2018-05-01

The coal gangue is one of the most abundant industrial solid wastes and pollute source of air and water. The use of coal gangue in the production of cement grouting material comforms to the basic state policy of environment protection and the circular using of natural resources. Through coal gangue processing experiment, coal gangue cement grouting materials making test, properties detection of properties and theoretical analysis, the paper studied the effects of coal gangue on the properties of cement grouting materials. It is found that at the range of 600 to 700 °C, the fluidity and the compressive and flexural strengths of the cement grouting materials increase with the rising up of the calcination temperatures of coal gangue. The optimum calcination temperature is around 700 °C. The part substitution of cement by the calcined coal gangue in the cement grouting material will improve the mechanical properties of the cement grouting material, even thought it will decrease its fluidity. The best substitution amount of cement by coal gangue is about 30%. The fluidity and the long term strength of the ordinary silicate cement grouting material is obviously higher than that of the sulphoaluminate cement one as well as that of the silicate-sulphoaluminate complex cement one.

Pancreatic β-Cell Membrane Fluidity and Toxicity Induced by Human Islet Amyloid Polypeptide Species

NASA Astrophysics Data System (ADS)

Pilkington, Emily H.; Gurzov, Esteban N.; Kakinen, Aleksandr; Litwak, Sara A.; Stanley, William J.; Davis, Thomas P.; Ke, Pu Chun

2016-02-01

Aggregation of human islet amyloid polypeptide (hIAPP) into fibrils and plaques is associated with pancreatic β-cell loss in type 2 diabetes (T2D). However, due to the rapidness of hIAPP conversion in aqueous phase, exactly which hIAPP species is responsible for the observed toxicity and through what mechanisms remains ambiguous. In light of the importance of understanding hIAPP toxicity for T2D here we show a biophysical scheme based on the use of a lipophilic Laurdan dye for examining MIN6 cell membranes upon exposure to fresh and oligomeric hIAPP as well as mature amyloid. It has been found that all three hIAPP species, especially fresh hIAPP, enhanced membrane fluidity and caused losses in cell viability. The cell generation of reactive oxygen species (ROS), however, was the most pronounced with mature amyloid hIAPP. The correlation between changes in membrane fluidity and cell viability and their lack of correlation with ROS production suggest hIAPP toxicity is elicited through both physical and biochemical means. This study offers a new insight into β-cell toxicity induced by controlled hIAPP species, as well as new biophysical methodologies that may prove beneficial for the studies of T2D as well as neurological disorders.

Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence.

PubMed

Sandor, Roman; Der, Christophe; Grosjean, Kevin; Anca, Iulia; Noirot, Elodie; Leborgne-Castel, Nathalie; Lochman, Jan; Simon-Plas, Françoise; Gerbeau-Pissot, Patricia

2016-09-01

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium

PubMed Central

Yun, Ou; Zeng, Xin-An; Brennan, Charles S.; Han, Zhong

2016-01-01

Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

Slow Freezing Coupled Static Magnetic Field Exposure Enhances Cryopreservative Efficiency—A Study on Human Erythrocytes

PubMed Central

Lin, Chun-Yen; Wei, Po-Li; Chang, Wei-Jen; Huang, Yung-Kai; Feng, Sheng-Wei; Lin, Che-Tong; Lee, Sheng-Yang; Huang, Haw-Ming

2013-01-01

The aim of this study was to assess the cryoprotective effect of static magnetic fields (SMFs) on human erythrocytes during the slow cooling procedure. Human erythrocytes suspended in 20% glycerol were slowly frozen with a 0.4-T or 0.8-T SMF and then moved to a −80°C freezer for 24 hr. The changes in survival rate, morphology, and metabolites of the thawed erythrocytes were examined. To understand possible cryoprotective mechanisms of SMF, membrane fluidity and dehydration stability of SMF-exposed erythrocytes were tested. For each test, sham-exposed erythrocytes were used as controls. Our results showed that freezing coupled with 0.4-T or 0.8-T SMFs significantly increased the relative survival ratios of the frozen-thawed erythrocytes by 10% and 20% (p<0.001), respectively. The SMFs had no effect on erythrocyte morphology and metabolite levels. However, membrane fluidity of the samples exposed to 0.8-T SMF decreased significantly (p<0.05) in the hydrophobic regions. For the dehydration stability experiments, the samples exposed to 0.8-T SMF exhibited significantly lower (p<0.05) hemolysis. These results demonstrate that a 0.8-T SMF decreases membrane fluidity and enhances erythrocyte membrane stability to resist dehydration damage caused by slow cooling procedures. PMID:23520546

Effects and Location of Coplanar and Noncoplanar PCB in a Lipid Bilayer: A Solid-State NMR Study.

PubMed

Totland, Christian; Nerdal, Willy; Steinkopf, Signe

2016-08-02

Coplanar and noncoplanar polychlorinated biphenyls (PCBs) are known to have different routes and degree of toxicity. Here, the effects of noncoplanar PCB 52 and coplanar PCB 77 present at 2 mol % in a model system consisting of POPC liposomes (50% hydrated) are investigated by solid-state (13)C and (31)P NMR at 298 K. Both PCBs intercalate horizontally in the outer part of the bilayer, near the segments of the acyl chain close to the glycerol group. Despite similar membrane locations, the coplanar PCB 77 shows little effect on the bilayer properties overall, except for the four nearest neighboring lipids, while the effect of PCB 52 is more dramatic. The first ∼2 layers of lipids around each PCB 52 in the bilayer form a high fluidity lamellar phase, whereas lipids beyond these layers form a lamellar phase with a slight increase in fluidity compared to a bilayer without PCB 52. Further, a third high mobility domain is observed. The explanation for this is the interference of several high fluidity lamellar phases caused by interactions of PCB 52 molecules in different leaflets of the model bilayer. This causes formation of high curvature toroidal region in the bilayer and might induce formation of channels.

Gradient separation of oligosaccharides and suppressing anomeric mutarotation with enhanced-fluidity liquid hydrophilic interaction chromatography.

PubMed

Bennett, Raffeal; Olesik, Susan V

2017-04-01

Enhanced fluidity liquid chromatography using the hydrophilic interaction retention mechanism (EFLC-HILIC) is studied as an alternative separation mode for analyzing oligosaccharides and other sugars. These carbohydrates, which are important for the study of foods and biological systems, are difficult to comprehensively profile and either require a non-green, expensive solvent (i.e. acetonitrile) or derivatization of the analytes at the expense of time, sample loss, and loss of quantitative information. These difficulties arise from the diverse isomerism, mutarotation, and lack of a useable chromophore/fluorophore for spectroscopic detection. Enhanced fluidity liquid chromatography is an alternative separation method that involves the use of conventional polar solvents, such as methanol/water mixtures, as the primary mobile phase component and liquid carbon dioxide (CO 2 ) as the modifier in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis and higher efficiency. This work illustrates an optimized EFLC-HILIC separation of a test mixture of oligosaccharides and simple sugars with a resolution greater than 1.3 and an analysis time decrease of over 35% compared to a conventional HPLC HILIC-mode analysis using acetonitrile/water mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

High-level iron mitigates fusaricidin-induced membrane damage and reduces membrane fluidity leading to enhanced drug resistance in Bacillus subtilis.

PubMed

Yu, Wen-Bang; Ye, Bang-Ce

2016-05-01

Fusaricidins are a class of cyclic lipopeptide antibiotics that have strong antifungal activities against plant pathogenic fungi and excellent bactericidal activities against Gram-positive bacteria. The mechanism through which fusaricidin exerts its action is not yet entirely clear. To investigate the mode of action of fusaricidin, we determined the physiological and transcriptional responses of Bacillus subtilis to fusaricidin treatment by using a systems-level approach. Our data show that fusaricidin rapidly induced the expression of σ(W) regulon and caused membrane damage in B. subtilis. We further demonstrated that ferric ions play multiple roles in the action of fusaricidin on B. subtilis. Iron deprivation blocked the formation of hydroxyl radical in the cells and significantly inhibited the bactericidal activity of fusaricidin. Conversely, high levels of iron (>2 mM) repressed the expression of BkdR regulon, resulting in a smaller cellular pool of branched-chain precursors for iso- and anteiso-branched fatty acids, which in turn led to a decrease in the proportion of branched-chain fatty acids in the membrane of B. subtilis. This change in membrane composition reduced its bilayer fluidity and increased its resistance to antimicrobial agents. In conclusion, our experiments uncovered some novel interactions and a synergism between cellular iron levels and drug resistance in Gram-positive bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Changes Caused by Fruit Extracts in the Lipid Phase of Biological and Model Membranes

PubMed Central

Pruchnik, Hanna; Oszmiański, Jan; Sarapuk, Janusz; Kleszczyńska, Halina

2010-01-01

The aim of the study was to determine changes incurred by polyphenolic compounds from selected fruits in the lipid phase of the erythrocyte membrane, in liposomes formed of erythrocyte lipids and phosphatidylcholine liposomes. In particular, the effect of extracts from apple, chokeberry, and strawberry on the red blood cell morphology, on packing order in the lipid hydrophilic phase, on fluidity of the hydrophobic phase, as well as on the temperature of phase transition in DPPC liposomes was studied. In the erythrocyte population, the proportions of echinocytes increased due to incorporation of polyphenolic compounds. Fluorimetry with a laurdan probe indicated increased packing density in the hydrophilic phase of the membrane in presence of polyphenolic extracts, the highest effect being observed for the apple extract. Using the fluorescence probes DPH and TMA-DPH, no effect was noted inside the hydrophobic phase of the membrane, as the lipid bilayer fluidity was not modified. The polyphenolic extracts slightly lowered the phase transition temperature of phosphatidylcholine liposomes. The studies have shown that the phenolic compounds contained in the extracts incorporate into the outer region of the erythrocyte membrane, affecting its shape and lipid packing order, which is reflected in the increasing number of echinocytes. The compounds also penetrate the outer part of the external lipid layer of liposomes formed of natural and DPPC lipids, changing its packing order. PMID:21423329

[Adhesive properties and related phenomena for powdered pharmaceuticals].

PubMed

Otsuka, A

1998-04-01

This report deals with adhesive properties and related phenomena of powdered materials including pharmaceuticals. The adhesive force between a powder particle and substrate as well as the tensile strength of a powder bed and tablet was measured. Various factors were found to affect powder adhesion. Physical properties such as the size, shape and surface roughness were examined. The adhesive force between a particle and substrate decreased remarkably in the presence of ultrafine particles, which is of interest since the addition of adequate amount of "glidant" causes an increase in powder fluidity. From a pharmaceutical point of view, temperature and humidity were essential to particle adhesion. For several organic substances, the adhesive force increased significantly at homologous temperatures more than ca. 0.7, suggesting the sintering mechanism to be operative. The adhsive force between polymer films and glass beads varied according to polymer and relative humidity. A close correlation of water sorbed by the polymer film with adhesive force was noted. In connection with powder fluidity, compaction properties were studied by the centrifugal and tapping methods. Apparent adhesion defined as the ratio of the adhesive force between two contacting particles to the external force acting on a particle was noted to be the primary determinant of the void fraction or the porosity of the powder bed, indicating that the probability of particle displacement essentially depended on apparent adhesion.

Quenching of cascade reaction between triplet and photochrome probes with nitroxide radicals. A novel labeling method in study of membranes and surface systems.

PubMed

Papper, V; Medvedeva, N; Fishov, I; Likhtenshtein, G I

2000-01-01

We proposed a new method for the study of molecular dynamics and fluidity of the living and model biomembranes and surface systems. The method is based on the measurements of the sensitized photoisomerization kinetics of a photochrome probe. The cascade triplet cis-trans photoisomerization of the excited stilbene derivative sensitized with the excited triplet Erythrosin B has been studied in a model liposome membrane. The photoisomerization reaction is depressed with nitroxide radicals quenching the excited triplet state of the sensitizer. The enhanced fluorescence polarization of the stilbene probe incorporated into liposome membranes indicates that the stilbene molecules are squeezed in a relatively viscous media of the phospholipids. Calibration of the "triple" cascade system is based on a previously proposed method that allows the measurement of the product of the quenching rate constant and the sensitizer's triplet lifetime, as well as the quantitative detection of the nitroxide radicals in the vicinity of the membrane surface. The experiment was conducted using the constant-illumination fluorescence technique. Sensitivity of the method using a standard commercial spectrofluorimeter is about 10(-12) mol of fluorescence molecules per sample and can be improved using an advanced fluorescence technique. The minimal local concentration of nitroxide radicals or any other quenchers being detected is about 10(-5) M. This method enables the investigation of any chemical and biological surface processes of microscopic scale when the minimal volume is about 10(-3) microL or less.

The protective effect of a 17°C holding time on boar sperm plasma membrane fluidity after exposure to 5°C.

PubMed

Casas, I; Althouse, G C

2013-02-01

The holding time (HT) is the period during which an ejaculate, either in a raw or diluted state, is held at 17°C before further processing for cold-storage. In boars, the HT positively influences select sperm quality parameters of semen cooled from 15 to 5°C, a range in temperature during which plasma membrane remodeling occurs. Objective insight into the effect of HT on plasma membrane organization remains unknown. Therefore, the present work sought to elucidate if HT contributes to minimizing alterations in boar sperm plasma membrane fluidity at the initial step of the cooling process in a cryopreservation practice (holding at 5°C) and in relation with select sperm quality parameters. Nineteen ejaculates from five boars were collected and processed according to different treatments: T1) Fresh diluted semen, 0h at 17°C; T2) Fresh diluted semen, 24h at 17°C (HT); T3) Sperm from T1 in a lactose-egg yolk (LEY) extender, 3h at 5°C; T4) Sperm from T2 in LEY, 3h at 5°C; T5) Sperm from T1 in LEY, 24h at 5°C; T6) Sperm from T2 in LEY, 24h at 5°C. Sperm motility was assessed using CASA, and sperm plasma membrane integrity and fluidity were evaluated by flow cytometry with dual labeling (M540/YO-PRO®-1). Results demonstrated that the lack of exposure to a HT (T5) results in reduced sample motility compared to those having a HT (T6), with sperm exposed to HT exhibiting less plasma membrane fluidity. Collectively, these results provide empirical evidence that incorporation of a HT in semen processing protects boar sperm against cold injury through maintenance of lipid architecture of the plasma membrane. Copyright © 2012 Elsevier Inc. All rights reserved.

A biophysical approach to daunorubicin interaction with model membranes: relevance for the drug's biological activity.

PubMed

Alves, Ana Catarina; Ribeiro, Daniela; Horta, Miguel; Lima, José L F C; Nunes, Cláudia; Reis, Salette

2017-08-01

Daunorubicin is extensively used in chemotherapy for diverse types of cancer. Over the years, evidence has suggested that the mechanisms by which daunorubicin causes cytotoxic effects are also associated with interactions at the membrane level. The aim of the present work was to study the interplay between daunorubicin and mimetic membrane models composed of different ratios of 1,2-dimyristoyl- sn -glycero- 3 -phosphocholine (DMPC), sphingomyelin (SM) and cholesterol (Chol). Several biophysical parameters were assessed using liposomes as mimetic model membranes. Thereby, the ability of daunorubicin to partition into lipid bilayers, its apparent location within the membrane and its effect on membrane fluidity were investigated. The results showed that daunorubicin has higher affinity for lipid bilayers composed of DMPC, followed by DMPC : SM, DMPC : Chol and lastly by DMPC : SM : Chol. The addition of SM or Chol into DMPC membranes not only increases the complexity of the model membrane but also decreases its fluidity, which, in turn, reduces the amount of anticancer drug that can partition into these mimetic models. Fluorescence quenching studies suggest a broad distribution of the drug across the bilayer thickness, with a preferential location in the phospholipid tails. The gathered data support that daunorubicin permeates all types of membranes to different degrees, interacts with phospholipids through electrostatic and hydrophobic bonds and causes alterations in the biophysical properties of the bilayers, namely in membrane fluidity. In fact, a decrease in membrane fluidity can be observed in the acyl region of the phospholipids. Ultimately, such outcomes can be correlated with daunorubicin's biological action, where membrane structure and lipid composition have an important role. In fact, the results indicate that the intercalation of daunorubicin between the phospholipids can also take place in rigid domains, such as rafts that are known to be involved in different receptor processes, which are important for cellular function. © 2017 The Author(s).

Higher membrane fluidity mediates the increased subcutaneous fatty acid content in pigs fed reduced protein diets.

PubMed

Lopes, P A; Martins, A P; Martins, S V; Madeira, M S; Santos, N C; Moura, T F; Prates, J A M; Soveral, G

2017-04-01

The production of pork with moderate amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the meat industry. Several studies indicate that dietary protein reduction during the growing-finishing period of pigs enhances IMF content, but its consequence on carcass fat deposition is still contradictory. In this study, we hypothesized that the effects of reduced protein diets (RPD), corrected or not with the limiting amino acid lysine, on subcutaneous fat deposition from pigs with distinct genotypes are mediated by adipose membranes biophysical properties. In total, 36 crossbred (Large White×Landrace×Pietrain - a lean genotype) and purebred (Alentejana breed - a fatty genotype) male pigs were randomly assigned to the control group, the RPD group or the reduced protein diet equilibrated for lysine (RPDL) group, allowing a 2×3 factorial arrangement (n=6). Backfat thickness and total fatty acid content were higher in Alentejana relative to crossbred pigs. Although dietary treatments did not change backfat thickness, RPD and RPDL increased total fatty acids content of subcutaneous fat. In order to understand this effect, adipose tissue membranes isolated from pig's subcutaneous fat were assayed for glycerol permeability and fluidity, using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-(trimethylamino)-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) probes. The glycerol transport across adipose membranes was not mediated by aquaglyceroporins and remained unchanged across dietary groups. Regardless of lysine correction, RPD increased membrane fluidity at the hydrocarbon region (lower DPH fluorescence anisotropy) in both genotypes of pigs. This result was associated with a lower ratio between oleic acid and linoleic acid on membrane's fatty acid composition. Adipose membrane's cholesterol content was independent from genotype and diet. Taken together, the present study shows that dietary protein reduction is successful in maintaining backfat thickness, although a negative side effect was observed on total fatty acids in subcutaneous fat, which may be due to changes in the fluidity of adipose membranes.

Spectral imaging toolbox: segmentation, hyperstack reconstruction, and batch processing of spectral images for the determination of cell and model membrane lipid order.

PubMed

Aron, Miles; Browning, Richard; Carugo, Dario; Sezgin, Erdinc; Bernardino de la Serna, Jorge; Eggeling, Christian; Stride, Eleanor

2017-05-12

Spectral imaging with polarity-sensitive fluorescent probes enables the quantification of cell and model membrane physical properties, including local hydration, fluidity, and lateral lipid packing, usually characterized by the generalized polarization (GP) parameter. With the development of commercial microscopes equipped with spectral detectors, spectral imaging has become a convenient and powerful technique for measuring GP and other membrane properties. The existing tools for spectral image processing, however, are insufficient for processing the large data sets afforded by this technological advancement, and are unsuitable for processing images acquired with rapidly internalized fluorescent probes. Here we present a MATLAB spectral imaging toolbox with the aim of overcoming these limitations. In addition to common operations, such as the calculation of distributions of GP values, generation of pseudo-colored GP maps, and spectral analysis, a key highlight of this tool is reliable membrane segmentation for probes that are rapidly internalized. Furthermore, handling for hyperstacks, 3D reconstruction and batch processing facilitates analysis of data sets generated by time series, z-stack, and area scan microscope operations. Finally, the object size distribution is determined, which can provide insight into the mechanisms underlying changes in membrane properties and is desirable for e.g. studies involving model membranes and surfactant coated particles. Analysis is demonstrated for cell membranes, cell-derived vesicles, model membranes, and microbubbles with environmentally-sensitive probes Laurdan, carboxyl-modified Laurdan (C-Laurdan), Di-4-ANEPPDHQ, and Di-4-AN(F)EPPTEA (FE), for quantification of the local lateral density of lipids or lipid packing. The Spectral Imaging Toolbox is a powerful tool for the segmentation and processing of large spectral imaging datasets with a reliable method for membrane segmentation and no ability in programming required. The Spectral Imaging Toolbox can be downloaded from https://uk.mathworks.com/matlabcentral/fileexchange/62617-spectral-imaging-toolbox .

Calcein release behavior from liposomal bilayer; influence of physicochemical/mechanical/structural properties of lipids.

PubMed

Maherani, Behnoush; Arab-Tehrany, Elmira; Kheirolomoom, Azadeh; Geny, David; Linder, Michel

2013-11-01

The design of the drug delivery depends upon different parameters. One of the most noticeable factors in design of the drug delivery is drug-release profile which determines the site of action, the concentration of the drug at the time of administration, the period of time that the drug must remain at a therapeutic concentration. To get a better understanding of drug release, large unilamellar liposomes containing calcein were prepared using 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-palmitoyl-sn-glycero-3-phosphocholine, and a mixture of them; calcein was chosen as a model of hydrophilic drug. The calcein permeability across liposomal membrane (with different compositions) was evaluated on the basis of the first-order kinetic by spectrofluorometer. Also, the effects of liposome composition/fluidity as well as the incubation temperature/pH were investigated. Furthermore, we simulated the digestion condition in the gastrointestinal tract in humans, to mimic human gastro-duodenal digestion to monitor calcein release during the course of the digestion process. In vitro digestion model ''pH stat'' was used to systematically examine the influence of pH/enzyme on phospholipid liposomes digestion under simulated gastro-duodenal digestion. The results revealed that calcein permeates across liposomal membrane without membrane disruption. The release rate of calcein from the liposomes depends on the number and fluidity of bilayers and its mechanical/physical properties such as permeability, bending elasticity. Chemo-structural properties of drugs like as partition coefficient (Log P), H-bonding, polar surface area (PSA) are also determinative parameter in release behavior. Finally, stimulated emission depletion (STED) microscopy was used to study calcein translocation through liposomal bilayers. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Essential oils from Inula japonica and Angelicae dahuricae enhance sensitivity of MCF-7/ADR breast cancer cells to doxorubicin via multiple mechanisms.

PubMed

Wu, Min; Li, Tingting; Chen, Lilan; Peng, Sugang; Liao, Wei; Bai, Ruolan; Zhao, Xue; Yang, Hong; Wu, Chunhui; Zeng, Hongjuan; Liu, Yiyao

2016-03-02

Angelicae dahurica (Hoffm.) Benth. & Hook.f.ex Franch. & Sav combined with Pueraria and Gastrodia elata Bl. combined with Inula japonica Thunb. are widely used in herb-pairs of traditional chinese medicine. Previous studies have shown that Angelicae dahuricae essential oil (ADO) enhanced puerarin internalization into ABCB1-overexpressed Caco-2 cells. These findings suggest the possibility that essential oils may enhance the absorption via certain mechanisms related to ABCB1 and reverse multidrug resistance (MDR). ADO and essential oils from Inula japonica (IJO) may reverse ABCB1-mediated MDR, but this ability has not been investigated in detail in the well-established cancer cell lines. In this study, the underlying molecular mechanisms were further investigated to examine how IJO and ADO reverse MDR in the resistant human breast cancer cell line of MCF-7/ADR. Also this work may help uncover the conceivable compatibility mechanisms of above herb-pairs involved in ABCB1. The MDR human breast cancer MCF-7/ADR cells were treated with IJO, its sesquiterpene component isoalantolactone (ISO) or ADOat non- cytotoxic concentrations. The MDR ability was examined by measuring the sensitivity to doxorubicin (DOX), DOX accumulation and efflux, ABCB1 ATPase activity, ABCB1 expression, membrane fluidity, and stability and localization of lipid rafts and caveolae. Finally, the molecular modeling was performed to postulate how ISO interacts with ABCB1. Treating MCF-7/ADR cells with IJ oil, ISO or AD oil reversed MDR 2- to 3-fold, without affecting the sensitivity of the non-MDR parental cell line. Mechanistic studies showed that these oils down-regulated mRNA and protein expression of ABCB1, and reduced the stability of lipid rafts in the cell membrane, which has previously been shown to reduce ABCB1-mediated transport. On the other hand, IJO, ISO and ADO did not inhibit ABCB1 ATPase activity, and fluorescence polarization experiments showed that low concentrations of the oils did not appear to alter membrane fluidity, unlike some MDR-reversing agents, ISO showed a higher docking score than verapamil but lower than dofequidar and tariquidar. Our results suggest that IJO, ISO and ADO could reverse MDR by down-regulating ABCB1 expression and reducing lipid raft stability. These findings may be useful for developing safer and effective MDR reversal agents and also help find out the compatibility mechanisms. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Not changes in membrane fluidity but proteotoxic stress triggers heat shock protein expression in Chlamydomonas reinhardtii.

PubMed

Rütgers, Mark; Muranaka, Ligia Segatto; Schulz-Raffelt, Miriam; Thoms, Sylvia; Schurig, Juliane; Willmund, Felix; Schroda, Michael

2017-12-01

A conserved reaction of all organisms exposed to heat stress is an increased expression of heat shock proteins (HSPs). Several studies have proposed that HSP expression in heat-stressed plant cells is triggered by an increased fluidity of the plasma membrane. Among the main lines of evidence in support of this model are as follows: (a) the degree of membrane lipid saturation was higher in cells grown at elevated temperatures and correlated with a lower amplitude of HSP expression upon a temperature upshift, (b) membrane fluidizers induce HSP expression at physiological temperatures, and (c) membrane rigidifier dimethylsulfoxide dampens heat-induced HSP expression. Here, we tested whether this holds also for Chlamydomonas reinhardtii. We show that heat-induced HSP expression in cells grown at elevated temperatures was reduced because they already contained elevated levels of cytosolic HSP70A/90A that apparently act as negative regulators of heat shock factor 1. We find that membrane rigidifier dimethylsulfoxide impaired translation under heat stress conditions and that membrane fluidizer benzyl alcohol not only induced HSP expression but also caused protein aggregation. These findings support the classical model for the cytosolic unfolded protein response, according to which HSP expression is induced by the accumulation of unfolded proteins. Hence, the membrane fluidity model should be reconsidered. © 2017 John Wiley & Sons Ltd.

The Effect of Combined Ezetimibe/Atorvastatin Therapy vs. Atorvastatin Monotherapy on the Erythrocyte Membrane Structure in Patients with Coronary Artery Disease: A Pilot Study.

PubMed

Jackowska, Paulina; Pytel, Edyta; Koter-Michalak, Maria; Olszewska-Banaszczyk, Małgorzata; Legęza, Aleksandra; Broncel, Marlena

2016-01-01

Erythrocytes play an important role in atherogenesis. An excessive accumulation of cholesterol in erythrocyte membranes leads to disruption of the erythrocytes. The aim of the study was to compare the effect of two different hypolipidemic therapies on the structure of erythrocyte membranes. The study included 18 patients with angiographic confirmed coronary artery disease who, despite at least 6 months of hypolipidemic treatment, had not achieved LDL-C < 70 mg/dL and 18 healthy individuals as the control group. The following parameters were studied: total cholesterol level and erythrocyte membrane fluidity, lipid peroxidation, SH groups in membrane protein and plasma lipids. We observed a decrease in TC (20%), LDL-C (35%), level of lipid peroxidation (25%) and total cholesterol in erythrocytes (23%), and an increase in HDL-C (8%) and erythrocyte membrane fluidity of subsurface layers (14%) after 6 months of 10 mg atorvastatin + 10 mg ezetimibe therapy, in comparison with healthy controls. In the group treated with 40 mg atorvastatin for 6 months, decreased LDL-C (23%), lipid peroxidation (37%) and membrane cholesterol concentration (18%) was noted, as well as an increase in erythrocyte membrane fluidity in the subsurface layers (12%). Both the combination therapy and the monotherapy lead to an improvement of erythrocyte membrane structure, whose parameters reached values close to those in the control healthy group.

Dynamics of sperm subpopulations based on motility and plasma membrane status in thawed ram spermatozoa incubated under conditions that support in vitro capacitation and fertilisation.

PubMed

García-Álvarez, Olga; Maroto-Morales, Alejandro; Ramón, Manuel; del Olmo, Enrique; Jiménez-Rabadán, Pilar; Fernández-Santos, M Rocio; Anel-López, Luis; Garde, J Julián; Soler, Ana J

2014-06-01

The present study evaluated modifications occurring in thawed ram spermatozoa during incubation in different media that supported in vitro capacitation and fertilisation, and examines how these changes relate to IVF. Thawed sperm samples were incubated under capacitating (Cap) and non-capacitating (non-Cap) conditions for 0, 1 and 2h and used in an IVF test. During incubation, changes related to membrane status and the motility pattern of spermatozoa were assessed, the latter being used to characterise sperm subpopulations. A significantly greater increase (P≤0.05) in the percentage of spermatozoa with higher membrane fluidity was observed in samples incubated with Cap medium from the beginning of incubation. In addition, changes over time in the distribution of the motile subpopulation were particularly evident when spermatozoa were incubated with Cap medium, with a noted increase in spermatozoa classified as 'hyperactivated like', with major changes occurring after 1h incubation. Both characteristics (i.e. membrane fluidity and the percentage of the hyperactivated-like subpopulation) were significantly related with in vitro fertility, and only sperm samples incubated with the Cap medium were capable of fertilising oocytes. These results support the idea that changes in sperm membrane fluidity and motility pattern (i.e. an increase in hyperactivated spermatozoa) are needed for fertilisation to take place.

Improved Mitochondrial Function in Brain Aging and Alzheimer Disease – the New Mechanism of Action of the Old Metabolic Enhancer Piracetam

PubMed Central

Leuner, Kristina; Kurz, Christopher; Guidetti, Giorgio; Orgogozo, Jean-Marc; Müller, Walter E.

2010-01-01

Piracetam, the prototype of the so-called nootropic drugs’ is used since many years in different countries to treat cognitive impairment in aging and dementia. Findings that piracetam enhances fluidity of brain mitochondrial membranes led to the hypothesis that piracetam might improve mitochondrial function, e.g., might enhance ATP synthesis. This assumption has recently been supported by a number of observations showing enhanced mitochondrial membrane potential, enhanced ATP production, and reduced sensitivity for apoptosis in a variety of cell and animal models for aging and Alzheimer disease. As a specific consequence, substantial evidence for elevated neuronal plasticity as a specific effect of piracetam has emerged. Taken together, this new findings can explain many of the therapeutic effects of piracetam on cognition in aging and dementia as well as different situations of brain dysfunctions. PMID:20877425

Starbursts and Wispy Drops : Surfactants Spreading on Gel Substrates

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Shomeek; Daniels, Karen; Behringer, Robert

2005-11-01

We report a phase diagram for a novel instability seen in drops of nonionic surfactant solution (Triton X-305) spreading on viscoelastic agar gel substrate . This system allows us to examine the effect of varying the effective fluidity/stiffness of aqueous substrates. The morphology is strongly affected by the substrate fluidity, ranging from spreading starbursts of arms on weak gels, to wispy drops on intermediate strength gels, to circular drops on stiff gels. We analyze the dynamics of spreading in the starburst phase, where the arm length grows as t ^3/4 at early times, independent of the gel strength and surfactant concentration. The number of arms is proportional to the surfactant concentration and inversely proportional to the gel strength. Ongoing work is exploring the effects of changing the drop volume.

Alterations of hepatocyte function with free radical generators and reparation or prevention with coffee polyphenols.

PubMed

Saidi Merzouk, Amel; Hafida, Merzouk; Medjdoub, Amel; Loukidi, Bouchra; Cherrak, Sabri; Merzouk, Sid Ahmed; Elhabiri, Mourad

2017-03-01

Liver diseases are linked in the majority of cases to oxidative stress that antioxidants could neutralize with reducing liver injury. Chlorogenic acid, a coffee polyphenol, possesses antioxidant prosperities. The aim of this study was to evaluate in vitro preventive and corrective effects of cholorogenic acid in hepatocyte toxicity induced by free radicals. Hepatocytes were isolated from adult male Wistar rats. To determine corrective effects and reparation, cells were first exposed to two free radical generators (hydrogen peroxide/iron sulfate for hydroxyl radical formation, and phenazine methosulfate/nicotinamide adenine dinucleotide for superoxide anion formation) for 12H and thereafter treated by chlorogenic acid (1 and 10 μM final concentration) for another 12H. To show preventive effects, cells were pretreated by chlorogenic acid and thereafter exposed to free radical generators. Hepatocyte proliferation, glucose uptake, ATP contents, membrane fluidity and integrity, and intracellular redox status were investigated after 24H culture. The results showed that chlorogenic acid reversed the decrease in cell proliferation, glucose uptake and ATP levels, the increased LDH release and the reduced membrane fluidity and restored the oxidant/antioxidant status under oxidative stress. When pre-treated with chlorogenic acid, hepatocytes became very resistant to oxidative conditions and cellular homeostasis was maintained. In conclusion, chlorogenic acid displayed not only corrective but also preventive effects in hepatocytes exposed to oxidative stress and could be beneficial in patients with or at risk of liver diseases.

Pro-inflammatory and anti-inflammatory compounds exert similar effects on P-glycoprotein in blood-brain barrier endothelial cells.

PubMed

Torres-Vergara, Pablo; Penny, Jeffrey

2018-06-01

The effects of anti-inflammatory glucocorticoids dexamethasone (DX) and hydrocortisone (HC), pro-inflammatory cytokine interleukin-1β (IL-1β) and dietary long-chain polyunsaturated fatty acids (PUFAs) on expression and activity of the ATP-binding cassette transporter P-glycoprotein (P-GP) were studied in porcine brain endothelial cells (PBECs). Primary PBECs were treated for 24 h with glucocorticoids, IL-1β and long-chain PUFAs. P-GP activity was determined by measuring intracellular calcein accumulation and P-GP expression by Western blotting. The effect of PUFAs on membrane fluidity was assessed by fluorescence recovery after photobleaching (FRAP). Dexamethasone, HC and IL-1β significantly increased P-GP expression and activity. The effect of IL-1β was attenuated by the IL-1 receptor antagonist (IL-1RA). This is the first report of the combined actions of IL-1β and IL-1RA on P-GP expression and the first evidence of glucocorticoid-mediated P-GP up-regulation in PBECs. Arachidonic acid (AA), docosahexaenoic acid (DHA) and eicosapentenoic acid (EPA) significantly decreased P-GP activity without affecting expression or membrane fluidity. AA, DHA and EPA counteracted IL-1β-mediated increases in P-GP activity, while AA and EPA, but not DHA, counteracted glucocorticoid-mediated increase in P-GP activity. While glucocorticoids and IL-1β possess opposing actions in inflammation, they demonstrate functional consistency by increasing P-GP expression and activity in PBECs. © 2018 Royal Pharmaceutical Society.

Phenotypic and genotypic correlates of daptomycin-resistant methicillin-susceptible Staphylococcus aureus clinical isolates.

PubMed

Kang, Kyoung-Mi; Mishra, Nagendra N; Park, Kun Taek; Lee, Gi-Yong; Park, Yong Ho; Bayer, Arnold S; Yang, Soo-Jin

2017-02-01

Daptomycin (DAP) has potent activity in vitro and in vivo against both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. DAP-resistance (DAP-R) in S. aureus has been mainly observed in MRSA strains, and has been linked to single nucleotide polymorphisms (SNPs) within the mprF gene leading to altered cell membrane (CM) phospholipid (PL) profiles, enhanced positive surface charge, and changes in CM fluidity. The current study was designed to delineate whether these same genotypic and phenotypic perturbations are demonstrated in clinically-derived DAP-R MSSA strains. We used three isogenic DAP-susceptible (DAP-S)/DAP-R strainpairs and compared: (i) presence of mprF SNPs, (ii) temporal expression profiles of the two key determinants (mprF and dltABCD) of net positive surface charge, (iii) increased production of mprF-dependent lysinylated-phosphatidylglycerol (L-PG), (iv) positive surface charge assays, and (v) susceptibility to cationic host defense peptides (HDPs) of neutrophil and platelet origins. Similar to prior data in MRSA, DAP-R (vs DAP-S) MSSA strains exhibited hallmark hot-spot SNPs in mprF, enhanced and dysregulated expression of both mprF and dltA, L-PG overproduction, HDP resistance and enhanced positive surface charge profiles. However, in contrast to most DAP-R MRSA strains, there were no changes in CM fluidity seen. Thus, charge repulsion via mprF-and dlt-mediated enhancement of positive surface charge may be the main mechanism to explain DAP-R in MSSA strains.

Viscoelastic properties of normal and cancerous human breast cells are affected differently by contact to adjacent cells.

PubMed

Schierbaum, Nicolas; Rheinlaender, Johannes; Schäffer, Tilman E

2017-06-01

Malignant transformation drastically alters the mechanical properties of the cell and its response to the surrounding cellular environment. We studied the influence of the physical contact between adjacent cells in an epithelial monolayer on the viscoelastic behavior of normal MCF10A, non-invasive cancerous MCF7, and invasive cancerous MDA-MB-231 human breast cells. Using an atomic force microscopy (AFM) imaging technique termed force clamp force mapping (FCFM) to record images of the viscoelastic material properties, we found that normal MCF10A cells are stiffer and have a lower fluidity at confluent than at sparse density. Contrarily, cancerous MCF7 and MDA-MB-231 cells do not stiffen and do not decrease their fluidity when progressing from sparse to confluent density. The behavior of normal MCF10A cells appears to be governed by the formation of stable cell-cell contacts, because their disruption with a calcium-chelator (EGTA) causes the stiffness and fluidity values to return to those at sparse density. In contrast, EGTA-treatment of MCF7 and MDA-MB-231 cells does not change their viscoelastic properties. Confocal fluorescence microscopy showed that the change of the viscoelastic behavior in MCF10A cells when going from sparse to confluent density is accompanied by a remodeling of the actin cytoskeleton into thick stress fiber bundles, while in MCF7 and MDA-MB-231 cells the actin cytoskeleton is only composed of thin and short fibers, regardless of cell density. While the observed behavior of normal MCF10A cells might be crucial for providing mechanical stability and thus in turn integrity of the epithelial monolayer, the dysregulation of this behavior in cancerous MCF7 and MDA-MB-231 cells is possibly a central aspect of cancer progression in the epithelium. We measured the viscoelastic properties of normal and cancerous human breast epithelial cells in different states of confluency using atomic force microscopy. We found that confluent normal cells are stiffer and have lower fluidity than sparse normal cells, which appears to be governed by the formation of cell-cell contacts. Contrarily, confluent cancer cells do not stiffen and not have a decreased fluidity compared to sparse cancer cells and their viscoelastic properties are independent of cell-cell contact formation. While the observed behavior of normal cells appears to be crucial for providing the mechanical stability and therefore the integrity of the epithelial monolayer, the dysregulation of this behavior in cancer cells might be a central aspect of early stage cancer progression and metastasis in the epithelium. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Goodbye Career, Hello Success.

ERIC Educational Resources Information Center

Komisar, Randy

2000-01-01

Success in today's economy means throwing out the old career rules. The "noncareer" career is driven by passion for the work and has the fluidity and flexibility needed in the contemporary workplace. (JOW)

Sensitive change of iso-branched fatty acid (iso-15:0) in Bacillus pumilus PAMC 23174 in response to environmental changes.

PubMed

Yi, Da-Hye; Sathiyanarayanan, Ganesan; Seo, Hyung Min; Kim, Jung-Ho; Bhatia, Shashi Kant; Kim, Yun-Gon; Park, Sung-Hee; Jung, Ji-Young; Lee, Yoo Kyung; Yang, Yung-Hun

2016-01-01

In this study, the environmental adaptive metabolic processes were investigated using a psychrotrophic polar bacterium Bacillus pumilus PAMC 23174 in response to various temperatures and nutrients, especially in regard to the synthesis of fatty acids. Fatty acid methyl ester analysis was performed using gas chromatography-mass spectrometry and we found that a sensitive changes in iso-branched fatty acid (iso-15:0) synthesis occurred when adjusting the nutritional ratio of branched chain fatty acids (anteiso/iso) with different temperatures, resulting in a change in the balance of anteiso- and iso-form fatty acids. We also observed that this Arctic bacterium preferred amino acid leucine for the synthesis of fatty acids. The increased and decreased synthesis of iso-form fatty acids in response to different temperatures and leucine preference, changes the fatty acid ratio in bacteria, which further affects the membrane fluidity and it is also directly correlated with survival of bacteria in an extreme environment. Hence, this study suggests that B. pumilus PAMC 23174 is a potential model organism for the analysis of the unique ecological adaptations of polar bacteria in changing and the extreme environments.

[Skeletal muscles, physical activity and health].

PubMed

Saltin, B; Helge, J W

2000-11-01

The metabolic capacity of skeletal muscle plays a significant role for insulin sensitivity and the blood lipid profile. The metabolic capacity of the muscle is a function of the individual's physical activity level. This is also true for the content of type IIa muscle fibres, which is reduced, and the number of capillaries, which is elevated with muscle usage. Several of these skeletal muscle features are risk factors for or linked with life-style induced diseases such as type II diabetes, hypertension, hyperlipemia and obesity. The central role of the skeletal muscle and its functional metabolic capacity for life style diseases highlights the importance of people maintaining daily physical activity. This article focuses on the link between the metabolic capacity of skeletal muscle and the metabolic syndrome and briefly discusses the explanations for this relationship. As one important aspect if skeletal muscle has a high capacity for lipid oxidation, then more saturated fatty acids are oxidised and more unsaturated fatty acids are built in the phospholipid fraction of the plasma membrane, giving it more fluidity and improved insulin sensitivity. Moreover, the article points at the role of these fatty acids in activating genes via the PPAR-receptor system essential for enzyme and transport proteins in the lipid metabolism.

What the Human Brain Likes About Facial Motion

PubMed Central

Schultz, Johannes; Brockhaus, Matthias; Bülthoff, Heinrich H.; Pilz, Karin S.

2013-01-01

Facial motion carries essential information about other people's emotions and intentions. Most previous studies have suggested that facial motion is mainly processed in the superior temporal sulcus (STS), but several recent studies have also shown involvement of ventral temporal face-sensitive regions. Up to now, it is not known whether the increased response to facial motion is due to an increased amount of static information in the stimulus, to the deformation of the face over time, or to increased attentional demands. We presented nonrigidly moving faces and control stimuli to participants performing a demanding task unrelated to the face stimuli. We manipulated the amount of static information by using movies with different frame rates. The fluidity of the motion was manipulated by presenting movies with frames either in the order in which they were recorded or in scrambled order. Results confirm higher activation for moving compared with static faces in STS and under certain conditions in ventral temporal face-sensitive regions. Activation was maximal at a frame rate of 12.5 Hz and smaller for scrambled movies. These results indicate that both the amount of static information and the fluid facial motion per se are important factors for the processing of dynamic faces. PMID:22535907

Why have relative rates of class mobility become more equal among women in Britain?

PubMed

Bukodi, Erzsébet; Goldthorpe, John H; Joshi, Heather; Waller, Lorraine

2017-09-01

In a previous paper it has been shown that across three cohorts of men and women born in Britain in 1946, 1958 and 1970 a gender difference exists in regard to relative rates of class mobility. For men these rates display an essential stability but for women they become more equal. The aim of the present paper is to shed light on the causes of this trend-or, that is, of increasing social fluidity-among women. We begin by considering a refined version of the perverse fluidity hypothesis: that is, one that proposes that part-time work leads to increasing downward worklife mobility among women that also entails downward intergenerational mobility and thus promotes greater fluidity. We do in fact find that the increase in fluidity is very largely, if not entirely, confined to women who have had at least one period of part-time work. However, a more direct test of the hypothesis is not supportive. We are then led to investigate whether it is not that part-time working itself is the crucial factor but rather that women who subsequently work part-time already differ from those who do not at entry into employment. We find that eventual full- and part-timers do not differ in their class origins nor, in any systematic way, in their educational qualifications. But there is a marked and increasing difference in the levels of employment at which they make their labour market entry. Eventual part-timers are more likely than eventual full-timers to enter in working-class positions, regardless of their class origins and qualifications. Insofar as these women are from more advantaged origins, they would appear not to seek to exploit their advantages to the same extent as do full-timers in order to advance their own work careers. And it is, then, in the downward mobility accepted by these women-who increase in number across the cohorts-that we would locate the main source of the weakening association between class origins and destinations that is revealed among women at large. © London School of Economics and Political Science 2017.

Using spin-label W-band EPR to study membrane fluidity profiles in samples of small volume

NASA Astrophysics Data System (ADS)

Mainali, Laxman; Hyde, James S.; Subczynski, Witold K.

2013-01-01

Conventional and saturation-recovery (SR) EPR at W-band (94 GHz) using phosphatidylcholine spin labels (labeled at the alkyl chain [n-PC] and headgroup [T-PC]) to obtain profiles of membrane fluidity has been demonstrated. Dimyristoylphosphatidylcholine (DMPC) membranes with and without 50 mol% cholesterol have been studied, and the results have been compared with similar studies at X-band (9.4 GHz) (L. Mainali, J.B. Feix, J.S. Hyde, W.K. Subczynski, J. Magn. Reson. 212 (2011) 418-425). Profiles of the spin-lattice relaxation rate (T1-1) obtained from SR EPR measurements for n-PCs and T-PC were used as a convenient quantitative measure of membrane fluidity. Additionally, spectral analysis using Freed's MOMD (microscopic-order macroscopic-disorder) model (E. Meirovitch, J.H. Freed J. Phys. Chem. 88 (1984) 4995-5004) provided rotational diffusion coefficients (R⊥ and R||) and order parameters (S0). Spectral analysis at X-band provided one rotational diffusion coefficient, R⊥. T1-1, R⊥, and R|| profiles reflect local membrane dynamics of the lipid alkyl chain, while the order parameter shows only the amplitude of the wobbling motion of the lipid alkyl chain. Using these dynamic parameters, namely T1-1, R⊥, and R||, one can discriminate the different effects of cholesterol at different depths, showing that cholesterol has a rigidifying effect on alkyl chains to the depth occupied by the rigid steroid ring structure and a fluidizing effect at deeper locations. The nondynamic parameter, S0, shows that cholesterol has an ordering effect on alkyl chains at all depths. Conventional and SR EPR measurements with T-PC indicate that cholesterol has a fluidizing effect on phospholipid headgroups. EPR at W-band provides more detailed information about the depth-dependent dynamic organization of the membrane compared with information obtained at X-band. EPR at W-band has the potential to be a powerful tool for studying membrane fluidity in samples of small volume, ˜30 nL, compared with a representative sample volume of ˜3 μL at X-band.

Biochemical characterization and membrane fluidity of membranous vesicles isolated from boar seminal plasma.

PubMed

Piehl, Lidia L; Cisale, Humberto; Torres, Natalia; Capani, Francisco; Sterin-Speziale, Norma; Hager, Alfredo

2006-05-01

Mammalian seminal plasma contains membranous vesicles (MV), which differ in composition and origin. Among these particles, human prostasomes and equine prostasome-like MV have been the most studied. The aim of the present work is to characterize the biochemical composition and membrane fluidity of MV isolated from boar seminal plasma. The MV from boar seminal plasma were isolated by ultracentrifugation and further purification by gel filtration on Sephadex G-200. The MV were examined by electron microscopy (EM), amount of cholesterol, total phospholipid, protein content, and phospholipid composition were analyzed. Membrane fluidity of MV and spermatozoa were estimated from the electron spin resonance (ESR) spectra of the 5-doxilstearic acid incorporated into the vesicle membranes by the order parameter (S). The S parameter gives a measure of degree of structural order in the membrane and is defined as the ratio of the spectral anisotropy in the membranes to the maximum anisotropy obtained in a rigidly oriented system. The S parameter takes into consideration that S = 1 for a rapid spin-label motion of about only one axis and S = 0 for a rapid isotropic motion. Intermediate S values between S = 0 and S = 1 represents the consequence of decreased membrane fluidity. The EM revealed the presence of bilaminar and multilaminar electron-dense vesicles. Cholesterol to phospholipid molar ratio from the isolated MV was 1.8. Phospholipid composition showed a predominance of sphingomyelin. The S parameter for porcine MV and for boar spermatozoa was 0.73 +/- 0.02 and 0.644 +/- 0.008, respectively, with the S for MV being greater (p < 0.001) than the S for spermatozoa. The high order for S found for boar MV was in agreement with the greater cholesterol/phospholipids ratio and the lesser ratio for phosphatidylcholine/sphingomyelin. Results obtained in the present work indicate that MV isolated from boar semen share many biochemical and morphological characteristics with equine prostasome-like MV and human prostasomes. The characteristics of the porcine MV of the seminal plasma, however, differed from those of boar sperm plasma membranes.

Ex vivo effects of ibogaine on the activity of antioxidative enzymes in human erythrocytes.

PubMed

Nikolić-Kokić, Aleksandra; Oreščanin-Dušić, Zorana; Spasojević, Ivan; Slavić, Marija; Mijušković, Ana; Paškulin, Roman; Miljević, Čedo; Spasić, Mihajlo B; Blagojević, Duško P

2015-04-22

Ibogaine is a naturally occurring alkaloid with psychotropic and metabotropic effects, derived from the bark of the root of the West African Tabernanthe iboga plant. The tribes of Kongo basin have been using iboga as a stimulant, for medicinal purposes, and in rite of passage ceremonies, for centuries. Besides, it has been found that this drug has anti-addictive effects. Previous studies have demonstrated that ibogaine changed the quantity of ATP and energy related enzymes as well as the activity of antioxidant enzymes in cells thus altering redox equilibrium in a time manner. In this work, the mechanism of its action was further studied by measuring the effects of ibogaine in human erythrocytes in vitro on ATP liberation, membrane fluidity and antioxidant enzymes activity. Heparinized human blood samples were incubated with ibogaine (10 and 20 μM) at 37°C for 1h. Blood plasma was separated by centrifugation and the levels of ATP and uric acid were measured 10 min after the addition of ibogaine using standard kits. The activity of copper-zinc superoxide dismutase (SOD1), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were measured in erythrocytes after incubation period. The stability of SOD1 activity was further tested through in vitro incubation with H2O2 and scanning of its electrophoretic profiles. Membrane fluidity was determined using an electron paramagnetic resonance spin-labelling method. Results showed that ibogaine treatment of erythrocytes in vitro increased ATP concentration in the blood plasma without changes in neither erythrocytes membrane fluidity nor uric acid concentration. Ibogaine also increased SOD1 activity in erythrocytes at both doses applied here. Treatment with 20 μM also elevated GR activity after in vitro incubation at 37°C. Electrophoretic profiles revealed that incubation with ibogaine mitigates H2O2 mediated suppression of SOD1 activity. Some of the effects of ibogaine seem to be mediated through its influence on energy metabolism, redox active processes and the effects of discrete fluctuations of individual reactive oxygen species on different levels of enzyme activities. Overall, ibogaine acts as a pro-antioxidant by increasing activity of antioxidative enzymes and as an adaptagene in oxidative distress. Copyright © 2015. Published by Elsevier Ireland Ltd.

Nanobubble Ultrasound Contrast Agents for Enhanced Delivery of Thermal Sensitizer to Tumors Undergoing Radiofrequency Ablation

PubMed Central

Perera, Reshani H.; Solorio, Luis; Wu, Hanping; Gangolli, Mihika; Silverman, Eric; Hernandez, Christopher; Peiris, Pubudu M.; Broome, Ann-Marie

2013-01-01

Purpose Pluronic has been shown to sensitize various tumor cell lines to chemotherapy and hyperthermia by altering the membrane fluidity, depleting ATP, and modulating the heat shock protein 70 expression. In our prior work, Pluronic was also used to formulate nanosized ultrasound contrast agents. In the current study we evaluate the use of these contrast agents as vehicles for image-guided delivery of Pluronic to improve outcomes of tumor radiofrequency (RF) ablation. Methods Lipid-shelled Pluronic nanobubbles were prepared and examined for size distribution, zeta potential, stability, biodistribution, accumulation of nanobubbles in the tumor, and treatment efficacy. LS174-T xenograft tumor-bearing mice were used to evaluate tumor growth suppression and measure treatment efficacy after RF ablation. Results The average diameter of Pluronic bubbles was 230 nm, and initial bubble echogenicity was 16 dB. In vitro, cells exposed to Pluronic nanobubbles exhibited low cytotoxicity in the absence of ultrasound, even if heat (43°C) was applied. When the cells were exposed to Pluronic nanobubbles, heat, and ultrasound; viability was significantly reduced. In vivo, tumors treated with ultrasound-modulated nanobubbles prior to RF ablation showed a significant reduction in growth compared to the RF alone (P<0.05). Conclusion Lipid and Pluronic-shelled, echogenic nanobubbles combined with ultrasound modulation can serve as an effective theranostic method for sensitization of tumors to RF ablation. PMID:23943542

Nanobubble ultrasound contrast agents for enhanced delivery of thermal sensitizer to tumors undergoing radiofrequency ablation.

PubMed

Perera, Reshani H; Solorio, Luis; Wu, Hanping; Gangolli, Mihika; Silverman, Eric; Hernandez, Christopher; Peiris, Pubudu M; Broome, Ann-Marie; Exner, Agata A

2014-06-01

Pluronic has been shown to sensitize various tumor cell lines to chemotherapy and hyperthermia by altering the membrane fluidity, depleting ATP, and modulating the heat shock protein 70 expression. In our prior work, Pluronic was also used to formulate nanosized ultrasound contrast agents. In the current study we evaluate the use of these contrast agents as vehicles for image-guided delivery of Pluronic to improve outcomes of tumor radiofrequency (RF) ablation. Lipid-shelled Pluronic nanobubbles were prepared and examined for size distribution, zeta potential, stability, biodistribution, accumulation of nanobubbles in the tumor, and treatment efficacy. LS174-T xenograft tumor-bearing mice were used to evaluate tumor growth suppression and measure treatment efficacy after RF ablation. The average diameter of Pluronic bubbles was 230 nm, and initial bubble echogenicity was 16 dB. In vitro, cells exposed to Pluronic nanobubbles exhibited low cytotoxicity in the absence of ultrasound, even if heat (43 ºC) was applied. When the cells were exposed to Pluronic nanobubbles, heat, and ultrasound; viability was significantly reduced. In vivo, tumors treated with ultrasound-modulated nanobubbles prior to RF ablation showed a significant reduction in growth compared to the RF alone (P<0.05). Lipid and Pluronic-shelled, echogenic nanobubbles combined with ultrasound modulation can serve as an effective theranostic method for sensitization of tumors to RF ablation.

Influence of gating design on microstructure and fluidity of thin sections AA320.0 cast hypo-eutectic Al-Si alloy

NASA Astrophysics Data System (ADS)

Ramadan, Mohamed

2018-05-01

Influence of gating design especially number of ingrates on microstructure and fluidity of thin sections of 2, 4, 6 mm AA320.0 cast hypo-eutectic Al-Si alloy was evaluated for sand casting molding technique. Increasing the number of ingates improves the microstructe to be fine and more globular. About 87 μm of α-Al grain size, 0.6 α-Al grain sphericity and 37 μm dendrite arm spacing DAS are achieved by using 4 ingates in gating system. Increasing the number of ingates up to 3 increases hardness, filling area and related fluditiy of all cast samples. The minimum thickness of 2.5 mm for each ingate should be considered in order to successfully production of high quality light weight thin sections castings in sand mold.

Development of Thin Section Zinc Die Casting Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodwin, Frank

2013-10-31

A new high fluidity zinc high pressure die casting alloy, termed the HF alloy, was developed during laboratory trials and proven in industrial production. The HF alloy permits castings to be achieved with section thicknesses of 0.3 mm or less. Technology transfer activities were conducted to develop usage of the HF high fluidity alloy. These included production of a brochure and a one-hour webinar on the HF alloy. The brochure was then sent to 1,184 product designers in the Interzinc database. There was excellent reception to this mailing, and from this initial contact 5 technology transfer seminars were conducted formore » 81 participants from 30 companies across a wide range of business sectors. Many of the successful applications to date involve high quality surface finishes. Design and manufacturing assistance was given for development of selected applications.« less

Alteration by prolactin of surface charge and membrane fluidity of rat 13762 mammary ascites tumor cells.

PubMed

Zarkower, D A; Plank, L D; Kunze, E; Keith, A; Todd, P; Hymer, W C

1984-03-01

Intraperitoneal injection of ovine prolactin (100 micrograms/d) in Fischer 344 rats bearing transplantable 13762 mammary ascites tumor (MAT) cells modifies the surface charge density and membrane fluidity of the tumor cells. In each of five experiments the mean electrophoretic mobility (epm) of MAT cells taken from prolactin-treated rats was significantly lower than that of cells from nonhormone-treated controls. Prolactin concentrations were increased in vivo by (a) direct intraperitoneal injection of ovine prolactin; (b) subcutaneous implantation of diethylstilbestrol-containing silastic capsules to produce pituitary prolactin secreting tumors; or (c) a single subcutaneous injection of polyestradiol phosphate, a long-acting estrogen. In an effort to establish that the prolactin effect was a direct one, two in vivo protocols were used: (a) MAT cells were coincubated with anterior pituitary halves obtained from nontumor-bearing littermates; or (b) rat or ovine prolactin was added to serum-free culture media containing MAT cells. In both protocols, the epm of the prolactin-treated cells was significantly lower. The isoelectric focusing pH of whole cells was increased by prolactin treatment from 4.93 to 5.12, consistent with a reduction in the number of surface carboxyl groups. The fluidity of membranes of treated cells was drastically increased, as measured by spin-label probe rotation rates. These combined results imply that the hormone exerts its effect by stimulating events in the cell that lead to a reduction of the average density of carboxylic acid residues on the tumor cell surface.

Effect of antihypertensive agents - captopril and nifedipine - on the functional properties of rat heart mitochondria

PubMed Central

Kancirová, Ivana; Jašová, Magdaléna; Waczulíková, Iveta; Ravingerová, Táňa; Ziegelhöffer, Attila; Ferko, Miroslav

2016-01-01

Objective(s): Investigation of acute effect on cellular bioenergetics provides the opportunity to characterize the possible adverse effects of drugs more comprehensively. This study aimed to investigate the changes in biochemical and biophysical properties of heart mitochondria induced by captopril and nifedipine antihypertensive treatment. Materials and Methods: Male, 12-week-old Wistar rats in two experimental models (in vivo and in vitro) were used. In four groups, the effects of escalating doses of captopril, nifedipine and combination of captopril + nifedipine added to the incubation medium (in vitro) or administered per os to rat (in vivo) on mitochondrial ATP synthase activity and membrane fluidity were monitored. Results: In the in vitro model we observed a significant inhibitory effect of treatment on the ATP synthase activity (P<0.05) with nonsignificant differences in membrane fluidity. Decrease in the value of maximum reaction rate Vmax (P<0.05) without any change in the value of Michaelis-Menten constant Km, indicative of a noncompetitive inhibition, was presented. At the in vivo level, we did not demonstrate any significant changes in the ATP synthase activity and the membrane fluidity in rats receiving captopril, nifedipine, and combined therapy. Conclusion: In vitro kinetics study revealed that antihypertensive drugs (captopril and nifedipine) directly interact with mitochondrial ATP synthase. In vivo experiment did not prove any acute effect on myocardial bioenergetics and suggest that drugs do not enter cardiomyocyte and have no direct effect on mitochondria. PMID:27482342

Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

PubMed

Beilke, Michael C; Beres, Martin J; Olesik, Susan V

2016-03-04

A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

Guerbet compounds

USDA-ARS?s Scientific Manuscript database

Guerbet alcohols are of significant commercial interest for various applications, including in lubricants and surfactant systems, due to their great fluidity range, high oxidative stability, and good lubricity imparted by the saturated hydrocarbon backbone, branching, and the presence of an OH group...

Modification of membrane cholesterol and its impact on frozen-thawed chicken sperm characteristics.

PubMed

Partyka, Agnieszka; Bonarska-Kujawa, Dorota; Sporniak, Marta; Strojecki, Maciej; Niżański, Wojciech

2016-10-01

This study was conducted to determine the changes in chicken sperm plasma membranes fluidity and polarity as lipid packing arrangement induced by cholesterol-loaded cyclodextrin (CLC) and 2-hydroxypropyl-β-cyclodextrin (HBCD) and how sperm cryopreservation outcomes are improved by these changes. Treatment with 2 mg HBCD supported the highest (P < 0.01) percentage of viable spermatozoa compared with the control and CLCs groups after cryopreservation. The percentage of post-thaw progressive and rapid sperm motility was highest in 2 mg HBCD (P < 0.01). After thawing, sperm treated with 1 or 2 mg CLC showed the highest anisotropy at 5, 21, 25 and 40°C (P < 0.01). At 25°C, the lowest anisotropy was observed in the thawed semen from the control group. The highest value (P < 0.01) of generalized polarization (GP) (0.5) at 5°C was observed in the 1 mg CLC treated sample. After 2 h of incubation, the highest percentage of viable spermatozoa was observed in the HBCD group in relation to the other treatments (P < 0.01). Exposure to 1 mg or 2 mg of CLC significantly decreased the percentage of live spermatozoa after thawing (P < 0.01). In conclusion, HBCD appears to play a role in the modification of sperm membranes, increasing their fluidity and preventing them against membrane phase transition to gel, thus minimizing freezing-thaw sperm damage. HBCD treatment enhances chicken sperm viability and motility after cryopreservation and subsequent storage. This novel procedure may be useful for improving the technology for cryopreservation of fowl spermatozoa.

The extent of the temperature-induced membrane remodeling in two closely related Bordetella species reflects their adaptation to diverse environmental niches

PubMed Central

Seydlova, Gabriela; Beranova, Jana; Bibova, Ilona; Dienstbier, Ana; Drzmisek, Jakub; Masin, Jiri; Fiser, Radovan; Konopasek, Ivo; Vecerek, Branislav

2017-01-01

Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane. In this study, we have analyzed the thermal adaptation in two closely related respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica. Although B. pertussis represents a pathogen strictly adapted to the human body temperature, B. bronchiseptica causes infection in a broad range of animals and survives also outside of the host. We applied GC-MS to determine the fatty acids of both Bordetella species grown at different temperatures and analyzed the membrane fluidity by fluorescence anisotropy measurement. In parallel, we also monitored the effect of growth temperature changes on the expression and production of several virulence factors. In response to low temperatures, B. pertussis adapted its fatty acid composition and membrane fluidity to a considerably lesser extent when compared with B. bronchiseptica. Remarkably, B. pertussis maintained the production of virulence factors at 24 °C, whereas B. bronchiseptica cells resumed the production only upon temperature upshift to 37 °C. This growth temperature-associated differential modulation of virulence factor production was linked to the phosphorylation state of transcriptional regulator BvgA. The observed differences in low-temperature adaptation between B. pertussis and B. bronchiseptica may result from selective adaptation of B. pertussis to the human host. We propose that the reduced plasticity of the B. pertussis membranes ensures sustained production of virulence factors at suboptimal temperatures and may play an important role in the transmission of the disease. PMID:28348085

Analytical studies into radiation-induced starch damage in black and white peppers

NASA Astrophysics Data System (ADS)

Sharif, M. M.; Farkas, J.

1993-07-01

Temperature dependency of the apparent viscosity of heat-gelatinized suspensions of untreated and irradiated pepper samples has been investigated. There was a close linear correlation between the logaritm of "fluidity" /reciprocal of the apparent viscosity) and the reciprocal absolute temperature of the measurement. The slope of the regression line(the temperature dependence of fluidity) increased with the radiation dose. Gelatinization thermograms of aqueous suspensions of ground pepper samples were obtained by differential scanning calorimetry. Temperature characteristics of heat-gelatinization endotherms showed no significant differences between untreated and irradiated samples. A colorimetric method for damaged starch, the estimation of reducing power, and the alcohol-induced turbidity of aqueous extracts showed statistically significant increases of starch damage at doses higher than 4 kGy. These indices of starch-depolymerization have been changed less dramatically by irradiation than the apparent viscosity of the heat-gelatinized suspensions.

Multiracial in Middle School: The Influence of Classmates and Friends on Changes in Racial Self-Identification.

PubMed

Echols, Leslie; Ivanich, Jerreed; Graham, Sandra

2017-11-27

In the present research, the influence of racial diversity among classmates and friends on changes in racial self-identification among multiracial youth was examined (n = 5,209; M age  = 10.56 years at the beginning of sixth grade). A novel individual-level measure of diversity among classmates based on participants' course schedules was utilized. The findings revealed that although there was some fluidity in multiracial identification at the beginning of middle school, changes in multiracial identification were more evident later in middle school. In addition, although diversity among classmates and friends both increased the likelihood of multiracial identification in the beginning of middle school, only diversity among friends mattered later in middle school, when fluidity in multiracial identification was at its peak. © 2017 The Authors. Child Development © 2017 Society for Research in Child Development, Inc.

Effects of thallium(I) and thallium(III) on liposome membrane physical properties.

PubMed

Villaverde, Marcela S; Verstraeten, Sandra V

2003-09-15

The hypothesis that thallium (Tl) interaction with membrane phospholipids could result in the alteration of membrane physical properties was investigated. Working with liposomes composed of brain phosphatidylcholine and phosphatidylserine, we found that Tl(+), Tl(3+), and Tl(OH)(3) (0.5-25 microM): (a) increased membrane surface potential, (b) decreased the fluidity of the anionic regions of the membrane, in association with an increased fluidity in the cationic regions, and (c) promoted the rearrangement of lipids through lateral phase separation. The magnitude of these effects followed the order Tl(3+), Tl(OH)(3)>Tl(+). In addition, Tl(3+) also decreased the hydration of phospholipid polar headgroups and induced membrane permeabilization. The present results show that Tl interacts with membranes inducing major alterations in the rheology of the bilayer, which could be partially responsible for the neurotoxic effects of this metal.

Electrostatic-Assisted Liquefaction of Porous Carbons

DOE PAGES

Li, Peipei; Schott, Jennifer A.; Zhang, Jinshui; ...

2017-10-10

Porous liquids are a newly developed porous material that combine unique fluidity with permanent porosity, which exhibit promising functionalities for a variety of applications. However, the apparent incompatibility between fluidity and permanent porosity makes the stabilization of porous nanoparticle with still empty pores in the dense liquid phase a significant challenging. For this study, by exploiting the electrostatic interaction between carbon networks and polymerized ionic liquids, we demonstrate that carbon-based porous nanoarchitectures can be well stabilized in liquids to afford permanent porosity, and thus opens up a new approach to prepare porous carbon liquids. Furthermore, we hope this facile synthesismore » strategy can be widely applicated to fabricate other types of porous liquids, such as those (e.g., carbon nitride, boron nitride, metal–organic frameworks, covalent organic frameworks etc.) also having the electrostatic interaction with polymerized ionic liquids, evidently advancing the development and understanding of porous liquids.« less

Stability and rheology of dilute TiO2-water nanofluids

PubMed Central

2011-01-01

The apparent wall slip (AWS) effect, accompanying the flow of colloidal dispersions in confined geometries, can be an important factor for the applications of nanofluids in heat transfer and microfluidics. In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique. The nanofluids, prepared from TiO2 rutile or anatase nanopowders by ultrasonic dispersing in water, were stabilized by adjusting the pH to the maximum zeta potential. The resulting stable nanofluid samples were dilute, below 0.7 vol.%. All the samples manifest Newtonian behavior with the fluidities almost unaffected by the presence of the dispersed phase. No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%. PMID:21711783

Pore helix domain is critical to camphor sensitivity of transient receptor potential vanilloid 1 channel.

PubMed

Marsakova, Lenka; Touska, Filip; Krusek, Jan; Vlachova, Viktorie

2012-04-01

The recent discovery that camphor activates and strongly desensitizes the capsaicin-sensitive and noxious heat-sensitive channel transient receptor potential vanilloid subfamily member 1 (TRPV1) has provided new insights and opened up new research paths toward understanding why this naturally occurring monoterpene is widely used in human medicine for its local counter-irritant, antipruritic, and anesthetic properties. However, the molecular basis for camphor sensitivity remains mostly unknown. The authors attempt to explore the nature of the activation pathways evoked by camphor and narrow down a putative interaction site at TRPV1. The authors transiently expressed wild-type or specifically mutated recombinant TRPV1 channels in human embryonic kidney cells HEK293T and recorded cation currents with the whole cell, patch clamp technique. To monitor changes in the spatial distribution of phosphatidylinositol 4,5-bisphosphate, they used fluorescence resonance energy transfer measurements from cells transfected with the fluorescent protein-tagged pleckstrin homology domains of phospholipase C. The results revealed that camphor modulates TRPV1 channel through the outer pore helix domain by affecting its overall gating equilibrium. In addition, camphor, which generally is known to decrease the fluidity of cell plasma membranes, may also regulate the activity of TRPV1 by inducing changes in the spatial distribution of phosphatidylinositol-4,5-bisphosphate on the inner leaflet of the plasma membrane. The findings of this study provide novel insights into the structural basis for the modulation of TRPV1 channel by camphor and may provide an explanation for the mechanism by which camphor modulates thermal sensation in vivo.

Experimental Determination of η/s for Finite Nuclear Matter.

PubMed

Mondal, Debasish; Pandit, Deepak; Mukhopadhyay, S; Pal, Surajit; Dey, Balaram; Bhattacharya, Srijit; De, A; Bhattacharya, Soumik; Bhattacharyya, S; Roy, Pratap; Banerjee, K; Banerjee, S R

2017-05-12

We present, for the first time, simultaneous determination of shear viscosity (η) and entropy density (s) and thus, η/s for equilibrated nuclear systems from A∼30 to A∼208 at different temperatures. At finite temperature, η is estimated by utilizing the γ decay of the isovector giant dipole resonance populated via fusion evaporation reaction, while s is evaluated from the nuclear level density parameter (a) and nuclear temperature (T), determined precisely by the simultaneous measurements of the evaporated neutron energy spectra and the compound nuclear angular momenta. The transport parameter η and the thermodynamic parameter s both increase with temperature, resulting in a mild decrease of η/s with temperature. The extracted η/s is also found to be independent of the neutron-proton asymmetry at a given temperature. Interestingly, the measured η/s values are comparable to that of the high-temperature quark-gluon plasma, pointing towards the fact that strong fluidity may be the universal feature of the strong interaction of many-body quantum systems.

Physiological and biochemical effects of 17β estradiol in aging female rat brain.

PubMed

Kumar, Pardeep; Taha, Asia; Kale, R K; Cowsik, S M; Baquer, Najma Zaheer

2011-07-01

Aging in females and males is considered as the end of natural protection against age related diseases like osteoporosis, coronary heart disease, diabetes, Alzheimer's disease and Parkinson's disease. These changes increase during menopausal condition in females when the level of estradiol is decreased. The objective of this study was to observe the changes in activities of monoamine oxidase, glucose transporter-4 levels, membrane fluidity, lipid peroxidation levels and lipofuscin accumulation occurring in brains of female rats of 3 months (young), 12 months (adult) and 24 months (old) age groups, and to see whether these changes are restored to normal levels after exogenous administration of estradiol (0.1 μg/g body weight for 1 month). The results obtained in the present work revealed that normal aging was associated with significant increases in the activity of monoamine oxidase, lipid peroxidation levels and lipofuscin accumulation in the brains of aging female rats, and a decrease in glucose transporter-4 level and membrane fluidity. Our data showed that estradiol treatment significantly decreased monoamine oxidase activity, lipid peroxidation and lipofuscin accumulation in brain regions of aging rats, and a reversal of glucose transporter-4 levels and membrane fluidity was achieved, therefore it can be concluded from the present findings that estradiol's beneficial effects seemed to arise from its antilipofuscin, antioxidant and antilipidperoxidative effects, implying an overall anti-aging action. The results of this study will be useful for pharmacological modification of the aging process and applying new strategies for control of age related disorders. Copyright © 2011 Elsevier Inc. All rights reserved.

Structural Characterization of Biocompatible Reverse Micelles Using Small-Angle X-ray Scattering, 31P Nuclear Magnetic Resonance, and Fluorescence Spectroscopy.

PubMed

Odella, Emmanuel; Falcone, R Darío; Ceolín, Marcelo; Silber, Juana J; Correa, N Mariano

2018-04-19

The most critical problem regarding the use of reverse micelles (RMs) in several fields is the toxicity of their partial components. In this sense, many efforts have been made to characterize nontoxic RM formulations on the basis of biological amphiphiles and/or different oils. In this contribution, the microstructure of biocompatible mixed RMs formulated by sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) and tri- n-octylphosphine oxide (TOPO) surfactants dispersed in the friendly solvent methyl laurate was studied by using SAXS and 31 P NMR and by following the solvatochromic behavior of the molecular probe 4-aminophthalimide (4-AP). The results indicated the presence of RM aggregates upon TOPO incorporation with a droplet size reduction and an increase in the interfacial fluidity in comparison with pure AOT RMs. When confined inside the mixed systems, 4-AP showed a red-edge excitation shift and confirmed the increment of interfacial fluidity upon TOPO addition. Also, the partition between the external nonpolar solvent and the RM interface and an increase in both the local micropolarity and the capability to form a hydrogen bond interaction between 4-AP and a mixed interface were observed. The findings have been explained in terms of the nonionic surfactant structure and its complexing nature expressed at the interfacial level. Notably, we show how two different approaches, i.e., SAXS and the solvatochromism of the probe 4-AP, can be used in a complementary way to enhance our understanding of the interfacial fluidity of RMs, a parameter that is difficult to measure directly.

Mechanical Characterization of Hybrid Vesicles Based on Linear Poly(Dimethylsiloxane-b-Ethylene Oxide) and Poly(Butadiene-b-Ethylene Oxide) Block Copolymers

PubMed Central

Gaspard, Jeffery; Casey, Liam M.; Rozin, Matt; Munoz-Pinto, Dany J.; Silas, James A.; Hahn, Mariah S.

2016-01-01

Poly(dimethylsiloxane-ethylene oxide) (PDMS-PEO) and poly(butadiene-b-ethylene oxide) (PBd-PEO) are two block copolymers which separately form vesicles with disparate membrane permeabilities and fluidities. Thus, hybrid vesicles formed from both PDMS-PEO and PBd-PEO may ultimately allow for systematic, application-specific tuning of vesicle membrane fluidity and permeability. However, given the relatively low strength previously noted for comb-type PDMS-PEO vesicles, the mechanical robustness of the resulting hybrid vesicles must first be confirmed. Toward this end, we have characterized the mechanical behavior of vesicles formed from mixtures of linear PDMS-PEO and linear PBd-PEO using micropipette aspiration. Tension versus strain plots of pure PDMS12-PEO46 vesicles revealed a non-linear response in the high tension regime, in contrast to the approximately linear response of pure PBd33-PEO20 vesicles. Remarkably, the area expansion modulus, critical tension, and cohesive energy density of PDMS12-PEO46 vesicles were each significantly greater than for PBd33-PEO20 vesicles, although critical strain was not significantly different between these vesicle types. PDMS12-PEO46/PBd33-PEO20 hybrid vesicles generally displayed graded responses in between that of the pure component vesicles. Thus, the PDMS12-PEO46/PBd33-PEO20 hybrid vesicles retained or exceeded the strength and toughness characteristic of pure PBd-PEO vesicles, indicating that future assessment of the membrane permeability and fluidity of these hybrid vesicles may be warranted. PMID:26999148

Membrane Fluidity Changes, A Basic Mechanism of Interaction of Gravity with Cells?

NASA Astrophysics Data System (ADS)

Kohn, Florian; Hauslage, Jens; Hanke, Wolfgang

2017-10-01

All life on earth has been established under conditions of stable gravity of 1g. Nevertheless, in numerous experiments the direct gravity dependence of biological processes has been shown on all levels of organization, from single molecules to humans. According to the underlying mechanisms a variety of questions, especially about gravity sensation of single cells without specialized organelles or structures for gravity sensing is being still open. Biological cell membranes are complex structures containing mainly lipids and proteins. Functional aspects of such membranes are usually attributed to membrane integral proteins. This is also correct for the gravity dependence of cells and organisms which is well accepted since long for a wide range of biological systems. However, it is as well established that parameters of the lipid matrix are directly modifying the function of proteins. Thus, the question must be asked, whether, and how far plain lipid membranes are affected by gravity directly. In principle it can be said that up to recently no real basic mechanism for gravity perception in single cells has been presented or verified. However, it now has been shown that as a basic membrane parameter, membrane fluidity, is significantly dependent on gravity. This finding might deliver a real basic mechanism for gravity perception of living organisms on all scales. In this review we summarize older and more recent results to demonstrate that the finding of membrane fluidity being gravity dependent is consistent with a variety of published laboratory experiments. We additionally point out to the consequences of these recent results for research in the field life science under space condition.

Evaluation of creative thinking in children with idiopathic epilepsy (absence epilepsy).

PubMed

Di Filippo, T; Parisi, L; Roccella, M

2012-02-01

Creativity represents the silent character of human behaviour. In children with epilepsy, cognitive performance of has mainly been investigated under the assumption that the disorder represents a risk factor for the development of intellectual function. In subjects with different forms of epilepsy, neuropsychologic disorders have been detected even when cognitive-global functioning is unimpaired. The cognitive functions of subjects with epilepsy have been widely studied, but their creativity has been never evaluated to date. The aim of this study was to describe the development of creative thinking in a group of children with absence epilepsy. The test battery included: the Torrance Test of Creative Thinking (TTCT), the Wechsler Intelligence Scale for Children-revised (WISC-R) and the Goodenough Human Figure Drawing Test. Statistical analysis (Mann-Whitney test) showed a statistically significant difference (P <0.05) in test scores between two groups of subjects (children with epilesy vs control group), with higher scores for figure originality, figure fluidity and figure elaboration in the control group. There was a significant correlation (Spearman's rho) between verbal IQ and verbal fluidity and verbal flexibility subscale scores and between performance IQ and figure elaboration, between total IQ and verbal fluidity and verbal flexibility subscales (P <0.05; r >0.30). Low scores on the figure originality subscales seem to confirm the hypothesis that adverse psychodynamic and relational factors impoverish autonomy, flexibility and manipulator interests. The communication channels between subjects with epilepsy and their family members were affected by the disorder, as were the type of emotional dynamics and affective flux.

Increased Isoprenoid Quinone Concentration Modulates Membrane Fluidity in Listeria monocytogenes at Low Growth Temperatures.

PubMed

Seel, Waldemar; Flegler, Alexander; Zunabovic-Pichler, Marija; Lipski, André

2018-07-01

Listeria monocytogenes is a food pathogen capable of growing at a broad temperature range from 50°C to refrigerator temperatures. A key requirement for bacterial activity and growth at low temperatures is the ability to adjust the membrane lipid composition to maintain cytoplasmic membrane fluidity. In this study, we confirmed earlier findings that the extents of fatty acid profile adaptation differed between L. monocytogenes strains. We were able to demonstrate for isolates from food that growth rates at low temperatures and resistance to freeze-thaw stress were not impaired by a lower adaptive response of the fatty acid composition. This indicated the presence of a second adaptation mechanism besides temperature-regulated fatty acid synthesis. For strains that showed weaker adaptive responses in their fatty acid profiles to low growth temperature, we could demonstrate a significantly higher concentration of isoprenoid quinones. Three strains even showed a higher quinone concentration after growth at 6°C than at 37°C, which is contradictory to the reduced respiratory activity at lower growth temperatures. Analyses of the membrane fluidity in vivo by measuring generalized polarization and anisotropy revealed modulation of the transition phase. Strains with increased quinone concentrations showed an expanded membrane transition phase in contrast to strains with pronounced adaptations of fatty acid profiles. The correlation between quinone concentration and membrane transition phase expansion was confirmed by suppression of quinone synthesis. A reduced quinone concentration resulted in a narrower transition phase. Expansion of the phase transition zone by increasing the concentration of non-fatty acid membrane lipids is discussed as an additional mechanism improving adaptation to temperature shifts for L. monocytogenes strains. IMPORTANCE Listeria monocytogenes is a foodborne pathogen with an outstanding temperature range for growth. The ability for growth at temperatures close to the freezing point constitutes a serious contamination potential for cold stored food. The only known mechanism of the species for adaptation of membrane fluidity is modification of the membrane fatty acid composition. We were able to demonstrate that, at least for some strains, this adaptation mechanism is supported by regulation of the menaquinone concentration. The increase of this neutral membrane lipid is correlated with fluidization of the membrane under low-temperature conditions and therefore represents a fatty acid-independent mechanism for adaptation to low temperatures. Copyright © 2018 American Society for Microbiology.

A novel kind of concrete superplasticizer based on aryl isocyanate polycondensates

NASA Astrophysics Data System (ADS)

Ding, Bei; Qian, Shanshan; Qiu, Ying; Wang, Yi; Zheng, Chunyang; Wang, Gaoming

2017-03-01

A novel superplasticizer was synthesized by polycondensation of Alkyl phenol phosphate and toluene diisocyanate grafting with methoxy polyoxyethylene ether (MPEG). The chemical structure and molecular weight of polycondensates molecules were determined by 1H nuclear magnetic resonance (NMR) and gel permeation chromatography respectively. The experimental results indicated that the polycondensates of Alkyl phenol phosphate and toluene diisocyanate grafting with MPEG not only exhibited good water-reducing properties but also demonstrated effective anti-clay abilities alone. Furthermore, the polycondensates showed good fluidity maintaining abilities within 1-3 h and good workability of concrete. The results of T500 Time experiments show that lower plastic viscosity of the polycondensates leads to fresh concrete much “looser” than conventional PCEs in self-compacting concrete.

Cholesterol segregates into submicrometric domains at the living erythrocyte membrane: evidence and regulation.

PubMed

Carquin, Mélanie; Conrard, Louise; Pollet, Hélène; Van Der Smissen, Patrick; Cominelli, Antoine; Veiga-da-Cunha, Maria; Courtoy, Pierre J; Tyteca, Donatienne

2015-12-01

Although cholesterol is essential for membrane fluidity and deformability, the level of its lateral heterogeneity at the plasma membrane of living cells is poorly understood due to lack of appropriate probe. We here report on the usefulness of the D4 fragment of Clostridium perfringens toxin fused to mCherry (theta*), as specific, non-toxic, sensitive and quantitative cholesterol-labeling tool, using erythrocyte flat membrane. By confocal microscopy, theta* labels cholesterol-enriched submicrometric domains in coverslip-spread but also gel-suspended (non-stretched) fresh erythrocytes, suggesting in vivo relevance. Cholesterol domains on spread erythrocytes are stable in time and space, restricted by membrane:spectrin anchorage via 4.1R complexes, and depend on temperature and sphingomyelin, indicating combined regulation by extrinsic membrane:cytoskeleton interaction and by intrinsic lipid packing. Cholesterol domains partially co-localize with BODIPY-sphingomyelin-enriched domains. In conclusion, we show that theta* is a useful vital probe to study cholesterol organization and demonstrate that cholesterol forms submicrometric domains in living cells.

The emergence of understanding in a computer model of concepts and analogy-making

NASA Astrophysics Data System (ADS)

Mitchell, Melanie; Hofstadter, Douglas R.

1990-06-01

This paper describes Copycat, a computer model of the mental mechanisms underlying the fluidity and adaptability of the human conceptual system in the context of analogy-making. Copycat creates analogies between idealized situations in a microworld that has been designed to capture and isolate many of the central issues of analogy-making. In Copycat, an understanding of the essence of a situation and the recognition of deep similarity between two superficially different situations emerge from the interaction of a large number of perceptual agents with an associative, overlapping, and context-sensitive network of concepts. Central features of the model are: a high degree of parallelism; competition and cooperation among a large number of small, locally acting agents that together create a global understanding of the situation at hand; and a computational temperature that measures the amount of perceptual organization as processing proceeds and that in turn controls the degree of randomness with which decisions are made in the system.

Detection of erythrocyte membrane structural abnormalities in lecithin: cholesterol acyltransferase deficiency using a spin label approach.

PubMed

Maraviglia, B; Herring, F G; Weeks, G; Godin, D V

1979-01-01

The membrane fluidity of erythrocytes from patients with Lecithin: cholesterol acyltransferase (LCAT) deficiency was studied by means of electron spin resonance. The temperature dependence of the separation of the outer extrema of the spectra of 2-(3-carboxy-propyl)-4,4-dimethyl, 2-tridecyl-3-oxazolidinyloxyl spin probe was monitored for normal, presumed carrier and clinically affected subjects. The temperature profile of controls was significantly different from that of the presumed carriers and the clinically affected individuals. The results show that the compositional abnormalities previously noted in erythrocyte membranes from patients with LCAT deficiency are associated with alterations in the physiocochemical state of the membrane. An investigation of the spectral lineshapes below 10 degrees C allowed a distinction to be made at the membrane level between clinically affected subjects and clinically normal heterozygous carriers. Alterations in the temperature dependence of elec-ron spin resonance parameters may provide a sensitive index of red cell membrane alterations in pathological states of generalized membrane involvement.

Influence of freezing stress on morphological alteration and biofilm formation by Listeria monocytogenes: relationship with cell surface hydrophobicity and membrane fluidity.

PubMed

Miladi, Hanene; Ammar, Emna; Ben Slama, Rihab; Sakly, Nawfel; Bakhrouf, Amina

2013-11-01

The morphological changes and adhesive property of three Listeria monocytogenes strains submitted to freezing stress (-20 °C) were studied. The atomic force micrographs showed a reduction in the cell size and an evolution to coccoid shape. The phenotypic slime production of L. monocytogenes and the expression of the adhesive gene were investigated before and after 10 months of incubation in salmon at -20°. Our results showed that after ten months, stressed stains become more adherent and able to produce slime. In addition, we noted that this pathogen presents same physiological changes to adapt to starvation conditions. The cellular fatty acids composition of adhered and floating cells of three L. monocytogenes strains was taken into consideration. The stressed strains presented different chain lengths and therefore an increase in the hydrophobicity level. Moreover, we noted that the adhesive property of L. monocytogenes strains affects the Benzalkonium chloride bacterial sensitivity which increased after biofilm formation.

Investigation of Resonant AC-DC Magnetic Field Effects.

DTIC Science & Technology

1987-07-31

phosphatidylethanolamine with smaller amounts of phosphatidylinosital and phosphatidic acid . The fluidity of the acyl chain region of these lipids at room temperature...fusion and lipid lateral separation in phosphatidylcholine- phosphatidic acid vesicles. Biochem 25:6978-6987. Liboff AR (1985): Cyclotron resonance in

Gallium alloy films investigated for use as boundary lubricants

NASA Technical Reports Server (NTRS)

1966-01-01

Gallium alloyed with other low melting point metals has excellent lubricant properties of fluidity and low vapor pressure for high temperature or vacuum environments. The addition of other soft metals reduces the corrosivity and formation of undesirable alloys normally found with gallium.

Development of laboratory test methods to replace the simulated high-temperature grout fluidity test : [summary].

DOT National Transportation Integrated Search

2014-06-01

Concretes remarkable role in construction depends on its marriage with reinforcing steel. Concrete is very strong in compression, but weak in tension, so reinforcing steel is added to increase tensile strength, yielding structural components capab...

Comparative study of hypocholesterolemic and hypolipidemic effects of conjugated linolenic acid isomers against induced biochemical perturbations and aberration in erythrocyte membrane fluidity.

PubMed

Saha, Siddhartha S; Chakraborty, Anirban; Ghosh, Santinath; Ghosh, Mahua

2012-06-01

The purpose of the study was to evaluate hypolipidemic and hypocholesterolemic activities of conjugated linolenic acid (CLnA) isomers, present in bitter gourd and snake gourd seed, in terms of amelioration of plasma lipid profile, lipoprotein oxidation and erythrocyte membrane fluidity after oral administration. Male albino rats were divided into six groups. Group 1 was control, and others were induced with oxidative stress by oral gavage of sodium arsenite (Sa). Group 2 was kept as treated control, and groups 3-6 were further treated with different oral doses of seed oils to maintaining definite concentration of CLnA isomers (0.5 and 1.0% of total lipid for each CLnA isomer). CLnA isomers normalized cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride contents in plasma and body weight of experimental rats and decreased cholesterol synthesis by reducing hepatic HMG-CoA reductase activity. Administration of Sa caused alteration in erythrocyte membrane fluidity due to increase in cholesterol and decrease in phospholipid content. Tissue cholesterol and lipid contents were also increased by Sa administration. These altered parameters were reversed by experimental oil administration. Protective effect of CLnA isomers on erythrocyte morphology was observed by atomic force microscopy (AFM). Fatty acid composition of erythrocyte membrane showed decrease in polyunsaturated fatty acid (PUFA) and increase in arachidonic acid content after Sa administration, which was normalized with the treatment of these oils. Supplementation of CLnA isomers restored erythrocyte membrane (EM) lipid peroxidation and lipoprotein oxidation. CLnA isomers, present in vegetable oils, showed potent hypolipidemic and hypocholesterolemic activities against biochemical perturbations.

Phase-field modeling of mixing/demixing of regular binary mixtures with a composition-dependent viscosity

NASA Astrophysics Data System (ADS)

Lamorgese, A.; Mauri, R.

2017-04-01

We simulate the mixing (demixing) process of a quiescent binary liquid mixture with a composition-dependent viscosity which is instantaneously brought from the two-phase (one-phase) to the one-phase (two-phase) region of its phase diagram. Our theoretical approach follows a standard diffuse-interface model of partially miscible regular binary mixtures wherein convection and diffusion are coupled via a nonequilibrium capillary force, expressing the tendency of the phase-separating system to minimize its free energy. Based on 2D simulation results, we discuss the influence of viscosity ratio on basic statistics of the mixing (segregation) process triggered by a rapid heating (quench), assuming that the ratio of capillary to viscous forces (a.k.a. the fluidity coefficient) is large. We show that, for a phase-separating system, at a fixed value of the fluidity coefficient (with the continuous phase viscosity taken as a reference), the separation depth and the characteristic length of single-phase microdomains decrease monotonically for increasing values of the viscosity of the dispersed phase. This variation, however, is quite small, in agreement with experimental results. On the other hand, as one might expect, at a fixed viscosity of the dispersed phase both of the above statistics increase monotonically as the viscosity of the continuous phase decreases. Finally, we show that for a mixing system the attainment of a single-phase equilibrium state by coalescence and diffusion is retarded by an increase in the viscosity ratio at a fixed fluidity for the dispersed phase. In fact, for large enough values of the viscosity ratio, a thin film of the continuous phase becomes apparent when two drops of the minority phase approach each other, which further retards coalescence.

Cleavage and crosslinking of polymeric coal structures during pyrolysis. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillen, D.F.; Malhotra, R.

1992-02-01

The ultimate objective of this project was to develop a better understanding of volatiles production to help optimize the yield and character of condensable coproducts during coal pyrolysis or mild gasification. The specific objectives were to (1) Develop pyrolysis procedures that minimize secondary reactions; and (2) Develop coal pretreatments that current knowledge suggests will prorate bond scission or prevent retrograde reactions. Our approach was to study the pyrolysis of coals and tar-loaded coals by using several techniques that span a range of heating rates and pressures. Slow-heating pyrolyses were performed at low pressures in the inlet of a field ionizationmore » mass spectrometer and at atmospheric pressures in a thermogravimetric analyzer. Moderately rapid-heating pyrolyses were performed in a vacuum TGA apparatus and in sealed silica ampules heated in a molten-salt bath. The fastest heating rates were achieved with laser pyrolysis at about 30,000 X/s. The high tar yield seen in this work where the entire volume of the coal particle becomes hot and fluid at very nearly the same time, taken together with the evident non-vapor transport of the tar under these conditions, emphasizes the importance of better understanding the development of fluidity during coal heating. This specifically includes the profound effects--long-recognized but poorly understood that mild oxidation has in suppressing coal fluidity. It also includes the more recently recognized fact that heating in the presence of an inert gas produced substantially greater fluidity than does heating in the presence of combustion gases, even if the conditions are very fuel rich and all the oxygen itself has already been consumed when the coal particles are encountered.« less

Cleavage and crosslinking of polymeric coal structures during pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillen, D.F.; Malhotra, R.

1992-02-01

The ultimate objective of this project was to develop a better understanding of volatiles production to help optimize the yield and character of condensable coproducts during coal pyrolysis or mild gasification. The specific objectives were to (1) Develop pyrolysis procedures that minimize secondary reactions; and (2) Develop coal pretreatments that current knowledge suggests will prorate bond scission or prevent retrograde reactions. Our approach was to study the pyrolysis of coals and tar-loaded coals by using several techniques that span a range of heating rates and pressures. Slow-heating pyrolyses were performed at low pressures in the inlet of a field ionizationmore » mass spectrometer and at atmospheric pressures in a thermogravimetric analyzer. Moderately rapid-heating pyrolyses were performed in a vacuum TGA apparatus and in sealed silica ampules heated in a molten-salt bath. The fastest heating rates were achieved with laser pyrolysis at about 30,000 X/s. The high tar yield seen in this work where the entire volume of the coal particle becomes hot and fluid at very nearly the same time, taken together with the evident non-vapor transport of the tar under these conditions, emphasizes the importance of better understanding the development of fluidity during coal heating. This specifically includes the profound effects--long-recognized but poorly understood that mild oxidation has in suppressing coal fluidity. It also includes the more recently recognized fact that heating in the presence of an inert gas produced substantially greater fluidity than does heating in the presence of combustion gases, even if the conditions are very fuel rich and all the oxygen itself has already been consumed when the coal particles are encountered.« less

Effects of in vitro supplementation with Syzygium cumini (L.) on platelets from subjects affected by diabetes mellitus.

PubMed

Raffaelli, Francesca; Borroni, Francesca; Alidori, Alessandro; Tirabassi, Giacomo; Faloia, Emanuela; Rabini, Rosa Anna; Giulietti, Alessia; Mazzanti, Laura; Nanetti, Laura; Vignini, Arianna

2015-01-01

The aim of this study was to assess the in vitro effects of Syzygium cumini (L.) (Sc) incubation on platelets from patients with diabetes, in order to test its efficacy as a potential adjuvant therapy. This study was performed on 77 patients with diabetes [29 in good (DMgc) and 48 in poor glycemic control (DMpc)] and 85 controls. In patients, platelets were analyzed at recruitment and after in vitro Sc incubation (final concentration of 200 µg/ml for 3 hours at 37 °C), whereas in controls only basal evaluation was performed. Lipoperoxide and nitric oxide (NO) levels, superoxide dismutase (SOD) and Na(+)/K(+) ATPase activities, total antioxidant capacity (TAC), and membrane fluidity tested by anisotropy of fluorescent probes 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 1-6-phenyl-1,3,5-hexatriene (DPH) were determined. Collagen-induced platelet aggregation was also evaluated. In vitro Sc activity counteracts oxidative damage, by improving platelet function through augmented membrane fluidity and Na(+)/K(+) ATPase activity; it also enhances antioxidant system functionality by increasing NO levels, SOD activity, and TAC and by decreasing lipoperoxide levels both in whole samples and in DMgc and DMpc. In addition, a slight tendency towards collagen-induced platelet aggregation decrease after Sc was observed. However, all these parameters, even after improvement, did not reach the levels of control subjects. Our results suggest that Sc may have a preventive and protective effect in oxidative damage progression associated with diabetes mellitus and its complications. If our data will be confirmed, Sc supplementation might become a further tool in the management of this disease, especially in view of its easy availability, safety, low cost, and absence of side effects.

A comparison study between different molecular weight polysaccharides derived from Lentinus edodes and their antioxidant activities in vivo.

PubMed

You, Ruxu; Wang, Kaiping; Liu, Jinyu; Liu, Maochang; Luo, Li; Zhang, Yu

2011-12-01

Polysaccharide purified Lentinus edodes (Berk.) Sing (Tricholomataceae) has been reported to attenuate oxidative stress in vitro. This study investigated whether polysaccharides from L. edodes with different molecular weight have protective effects against oxidative stress induced by D-galactose (D-gal) in vivo, and determined the specific relationship between molecular weight and antioxidant activity. In the present study, we successfully obtained three purified polysaccharides, coded as LT1, LT2, and LT3, and their molecular weights were 25.5, 306.2, and 605.4 kDa, respectively. The D-gal-treated mice received three polysaccharides once daily for 60 days. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), the content of malondialdehyde (MDA), and erythrocyte membrane fluidity were measured to evaluate the changes of the antioxidant ability. It was demonstrated that the administration of LT1, LT2, and LT3 could improve the antioxidant status to different levels. Furthermore, LT2 exhibited the highest antioxidant ability among these samples in vivo. Indeed, LT2 significantly decreased the content of MDA in liver (15.91 ± 0.31 versus 23.79 ± 1.18 nmol/mg protein for the model group, p < 0.05), enhanced the fluidity of erythrocyte membrane (2.458 ± 0.023 versus 2.167 ± 0.024 for the model group, p < 0.05), and increased the activities of SOD (147.19 ± 4.90 versus 82.26 ± 5.55 units/mg protein for the model group, p < 0.05) and GSH-Px (310.91 ± 6.24 versus 243.64 ± 6.77 units/mg protein for the model group, p < 0.05) in liver. The LT2 had a potential to be used as a novel natural antioxidant.

Double-Vacuum-Bag Process for Making Resin-Matrix Composites

NASA Technical Reports Server (NTRS)

Bradford, Larry J.

2007-01-01

A double-vacuum-bag process has been devised as a superior alternative to a single-vacuum-bag process used heretofore in making laminated fiber-reinforced resin-matrix composite-material structural components. This process is applicable to broad classes of high-performance matrix resins including polyimides and phenolics that emit volatile compounds (solvents and volatile by-products of resin-curing chemical reactions) during processing. The superiority of the double-vacuum-bag process lies in enhanced management of the volatile compounds. Proper management of volatiles is necessary for making composite-material components of high quality: if not removed and otherwise properly managed, volatiles can accumulate in interior pockets as resins cure, thereby forming undesired voids in the finished products. The curing cycle for manufacturing a composite laminate containing a reactive resin matrix usually consists of a two-step ramp-and-hold temperature profile and an associated single-step pressure profile as shown in Figure 1. The lower-temperature ramp-and-hold step is known in the art as the B stage. During the B stage, prepregs are heated and volatiles are generated. Because pressure is not applied at this stage, volatiles are free to escape. Pressure is applied during the higher-temperature ramp-and-hold step to consolidate the laminate and impart desired physical properties to the resin matrix. The residual volatile content and fluidity of the resin at the beginning of application of consolidation pressure are determined by the temperature and time parameters of the B stage. Once the consolidation pressure is applied, residual volatiles are locked in. In order to produce a void-free, high-quality laminate, it is necessary to design the curing cycle to obtain the required residual fluidity and the required temperature at the time of application of the consolidation pressure.

The effect of pentoxifylline on spontaneous and experimental metastasis of the mouse Neuro2a neuroblastoma.

PubMed

Amirkhosravi, A; Warnes, G; Biggerstaff, J; Malik, Z; May, K; Francis, J L

1997-07-01

Pentoxifylline (PTX) has been reported to have both direct and indirect anti-tumor effects in experimental tumor models. We studied the effect of PTX on (1) the proliferation of Neuro2a mouse neuroblastoma cells in vitro and in vivo, (2) spontaneous and experimental metastasis, (3) tumor cell membrane fluidity and (4) adhesion to a fibronectin-coated surface. PTX significantly reduced the proliferation of Neuro2a cells in vitro as determined by DNA measurement (P < 0.01) and total cell count (P < 0.02). In vivo, PTX reduced the growth of subcutaneously transplanted primary tumors in syngeneic A/J mice (P < 0.01; n = 15). All seven animals (100%) receiving intravenous tumor cells developed extensive liver metastasis. In contrast, only 1/11 (9%) of animals pre-treated with oral PTX and injected with PTX-treated cells developed liver metastases. Of five mice receiving PTX-treated cells without oral pretreatment of PTX, two out of five (40%) developed liver metastases. There was a slight, but not significant (P = 0.08) increase in both experimental and spontaneous lung metastases formation in PTX-treated animals. However, tumor nodule formation on the lung surface was inefficient. PTX also increased membrane fluidity of the Neuro2a cells and significantly decreased tumor cell adhesion to fibronectin-coated microtiter wells (P < 0.01). We conclude that PTX has a cytostatic effect on the Neuro2a mouse neuroblastoma and exerts an anti-tumor effect on liver metastases following intravenous administration of neuroblastoma cells. Whether these results are directly related to the changes in membrane properties caused by pentoxifylline remains to be established.

The extent of the temperature-induced membrane remodeling in two closely related Bordetella species reflects their adaptation to diverse environmental niches.

PubMed

Seydlova, Gabriela; Beranova, Jana; Bibova, Ilona; Dienstbier, Ana; Drzmisek, Jakub; Masin, Jiri; Fiser, Radovan; Konopasek, Ivo; Vecerek, Branislav

2017-05-12

Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane. In this study, we have analyzed the thermal adaptation in two closely related respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica Although B. pertussis represents a pathogen strictly adapted to the human body temperature, B. bronchiseptica causes infection in a broad range of animals and survives also outside of the host. We applied GC-MS to determine the fatty acids of both Bordetella species grown at different temperatures and analyzed the membrane fluidity by fluorescence anisotropy measurement. In parallel, we also monitored the effect of growth temperature changes on the expression and production of several virulence factors. In response to low temperatures, B. pertussis adapted its fatty acid composition and membrane fluidity to a considerably lesser extent when compared with B. bronchiseptica Remarkably, B. pertussis maintained the production of virulence factors at 24 °C, whereas B. bronchiseptica cells resumed the production only upon temperature upshift to 37 °C. This growth temperature-associated differential modulation of virulence factor production was linked to the phosphorylation state of transcriptional regulator BvgA. The observed differences in low-temperature adaptation between B. pertussis and B. bronchiseptica may result from selective adaptation of B. pertussis to the human host. We propose that the reduced plasticity of the B. pertussis membranes ensures sustained production of virulence factors at suboptimal temperatures and may play an important role in the transmission of the disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Changing rooster sperm membranes to facilitate cryopreservation

USDA-ARS?s Scientific Manuscript database

Cryopreservation damages rooster sperm membranes. Part of this damage is due to membrane transitioning from the fluid to the gel state as temperature is reduced. This damage may be prevented by increasing membrane fluidity at low temperatures by incorporating cholesterol or unsaturated lipids into t...

Fluid Movement and Creativity

ERIC Educational Resources Information Center

Slepian, Michael L.; Ambady, Nalini

2012-01-01

Cognitive scientists describe creativity as fluid thought. Drawing from findings on gesture and embodied cognition, we hypothesized that the physical experience of fluidity, relative to nonfluidity, would lead to more fluid, creative thought. Across 3 experiments, fluid arm movement led to enhanced creativity in 3 domains: creative generation,…

Cybergirls: Negotiating Social Identities on Cybersites

ERIC Educational Resources Information Center

Guzzetti, Barbara J.

2006-01-01

Cyberspace has been regarded as an ideal site for adolescents' identity exploration since it is socially mediated. Liberal cyberfeminists argue that virtual spaces promote gender equality, fluidity, and unity through body-free interactions. This study investigated the cybersites frequented by two adolescent girls who eschewed typical…

The formation of ordered nanoclusters controls cadherin anchoring to actin and cell–cell contact fluidity

PubMed Central

Strale, Pierre-Olivier; Duchesne, Laurence; Peyret, Grégoire; Montel, Lorraine; Nguyen, Thao; Png, Evelyn; Tampé, Robert; Troyanovsky, Sergey; Hénon, Sylvie; Ladoux, Benoit

2015-01-01

Oligomerization of cadherins could provide the stability to ensure tissue cohesion. Cadherins mediate cell–cell adhesion by forming trans-interactions. They form cis-interactions whose role could be essential to stabilize intercellular junctions by shifting cadherin clusters from a fluid to an ordered phase. However, no evidence has been provided so far for cadherin oligomerization in cellulo and for its impact on cell–cell contact stability. Visualizing single cadherins within cell membrane at a nanometric resolution, we show that E-cadherins arrange in ordered clusters, providing the first demonstration of the existence of oligomeric cadherins at cell–cell contacts. Studying the consequences of the disruption of the cis-interface, we show that it is not essential for adherens junction formation. Its disruption, however, increased the mobility of junctional E-cadherin. This destabilization strongly affected E-cadherin anchoring to actin and cell–cell rearrangement during collective cell migration, indicating that the formation of oligomeric clusters controls the anchoring of cadherin to actin and cell–cell contact fluidity. PMID:26195669

Thermophysical Properties of Fluid Latent Heat Storage Material using Urea-Water Mixture

NASA Astrophysics Data System (ADS)

Hokamura, Taku; Ohkubo, Hidetoshi; Ashizawa, Kiyonori

This study is concerned with the measurement of thermophysical properties of a urea-water mixture with the aim of adopting the mixture as a latent heat storage material for air-conditioning systems. The urea-water mixture is made of natural substances and has a good fluidity. The urea concentration in the mixture was controlled by measuring the refractive index of the mixture. Being a multi-component substance, a urea-water solution has a liquid-solid co-existent phase on a phase-diagram. Therefore, the liquidus temperature was measured to establish a relationship between the fraction of the solid-phase and temperature. Furthermore, apparent values of specific heat and coefficient of viscosity were measured in the two-phase region where the solid phase is ice. The apparent specific heat and coefficient of viscosity were measure by using an adiabatic calorimeter and a stirring torque meter respectively. The results revealed that the urea-water mixture can probably be used as a latent heat storage material of good fluidity.

Interaction of nanoparticles with lipid membranes: a multiscale perspective

NASA Astrophysics Data System (ADS)

Montis, Costanza; Maiolo, Daniele; Alessandri, Ivano; Bergese, Paolo; Berti, Debora

2014-05-01

Freestanding lipid bilayers were challenged with 15 nm Au nanospheres either coated by a citrate layer or passivated by a protein corona. The effect of Au nanospheres on the bilayer morphology, permeability and fluidity presents strong differences or similarities, depending on the observation length scale, from the colloidal to the molecular domains. These findings suggest that the interaction between nanoparticles and lipid membranes should be conveniently treated as a multiscale phenomenon.Freestanding lipid bilayers were challenged with 15 nm Au nanospheres either coated by a citrate layer or passivated by a protein corona. The effect of Au nanospheres on the bilayer morphology, permeability and fluidity presents strong differences or similarities, depending on the observation length scale, from the colloidal to the molecular domains. These findings suggest that the interaction between nanoparticles and lipid membranes should be conveniently treated as a multiscale phenomenon. Electronic supplementary information (ESI) available: All the experimental details, figures and tables. See DOI: 10.1039/c4nr00838c

Multiscale analysis of the correlation of processing parameters on viscidity of composites fabricated by automated fiber placement

NASA Astrophysics Data System (ADS)

Han, Zhenyu; Sun, Shouzheng; Fu, Yunzhong; Fu, Hongya

2017-10-01

Viscidity is an important physical indicator for assessing fluidity of resin that is beneficial to contact resin with the fibers effectively and reduce manufacturing defects during automated fiber placement (AFP) process. However, the effect of processing parameters on viscidity evolution is rarely studied during AFP process. In this paper, viscidities under different scales are analyzed based on multi-scale analysis method. Firstly, viscous dissipation energy (VDE) within meso-unit under different processing parameters is assessed by using finite element method (FEM). According to multi-scale energy transfer model, meso-unit energy is used as the boundary condition for microscopic analysis. Furthermore, molecular structure of micro-system is built by molecular dynamics (MD) method. And viscosity curves are then obtained by integrating stress autocorrelation function (SACF) with time. Finally, the correlation characteristics of processing parameters to viscosity are revealed by using gray relational analysis method (GRAM). A group of processing parameters is found out to achieve the stability of viscosity and better fluidity of resin.

A Fluid Sea in the Mariana Islands: Community Archaeology and Mapping the Seascape of Saipan

NASA Astrophysics Data System (ADS)

McKinnon, Jennifer; Mushynsky, Julie; Cabrera, Genevieve

2014-06-01

This paper applies both a community archaeology and seascape approach to the investigation of the sea and its importance to the Indigenous community on the island of Saipan in the Mariana Islands in western Oceania. It examines data collected during a community project including archaeological sites, oral histories, lived experiences and contemporary understandings of both tangible and intangible maritime heritage to explore Indigenous connections with the sea and better define the seascape. What the seascape of Saipan conveys in the larger sense is the true fluidity of the sea. In this instance fluidity has more than one connotation; it refers to the sea as both a substance and an idea that permeates and flows into all aspects of Indigenous life. Chamorro and Carolinian people of Saipan identify themselves as having an ancestral connection with the sea that they continue to maintain to this day as they engage in daily activities within their seascape.

In vivo collective cell migration requires an LPAR2-dependent increase in tissue fluidity

PubMed Central

Kuriyama, Sei; Theveneau, Eric; Benedetto, Alexandre; Parsons, Maddy; Tanaka, Masamitsu; Charras, Guillaume; Kabla, Alexandre

2014-01-01

Collective cell migration (CCM) and epithelial–mesenchymal transition (EMT) are common to cancer and morphogenesis, and are often considered to be mutually exclusive in spite of the fact that many cancer and embryonic cells that have gone through EMT still cooperate to migrate collectively. Here we use neural crest (NC) cells to address the question of how cells that have down-regulated cell–cell adhesions can migrate collectively. NC cell dissociation relies on a qualitative and quantitative change of the cadherin repertoire. We found that the level of cell–cell adhesion is precisely regulated by internalization of N-cadherin downstream of lysophosphatidic acid (LPA) receptor 2. Rather than promoting the generation of single, fully mesenchymal cells, this reduction of membrane N-cadherin only triggers a partial mesenchymal phenotype. This intermediate phenotype is characterized by an increase in tissue fluidity akin to a solid-like–to–fluid-like transition. This change of plasticity allows cells to migrate under physical constraints without abolishing cell cooperation required for collectiveness. PMID:25002680

Characterization of Storage-Induced Red Blood Cell Hemolysis Using Raman Spectroscopy.

PubMed

Gautam, Rekha; Oh, Joo-Yeun; Marques, Marisa B; Dluhy, Richard A; Patel, Rakesh P

2018-06-11

The therapeutic efficacy and safety of stored red blood cells (RBCs) relies on minimal in-bag hemolysis. The accuracy of current methods of measuring hemolysis can suffer as a result of specimen collection and processing artefacts. To test whether Raman spectroscopy could be used to assess hemolysis. RBCs were stored for as long as 42 days. Raman spectra of RBCs were measured before and after washing, and hemolysis was measured in supernatant by visible spectroscopy. Raman spectra indicated increased concentrations of oxyhemoglobin (oxyHb) and methemoglobin (metHb), and decreased membrane fluidity with storage age. Changes in oxyHb and metHb were associated with the intraerythrocytic and extracellular fractions, respectively. Hemolysis increased in a storage age-dependent manner. Changes in Raman bands reflective of oxyHb, metHb, and RBC membranes correlated with hemolysis; the most statistically significant change was an increased intensity of metHb and decreased membrane fluidity. These data suggest that Raman spectroscopy may offer a new label-free modality to assess RBC hemolysis during cold storage.

Influence of menhaden oil on mitochondrial respiration in BHE rats.

PubMed

Kim, M J; Berdanier, C D

1989-11-01

The effects of corn or menhaden oil and thyroxine treatment on hepatic mitochondrial respiration was studied. BHE rats were fed a 64% sucrose, 6% corn, or menhaden oil diet until they were 60-70 days of age. Succinate-supported mitochondrial respiration was studied at 3 degrees C intervals from 4 to 40 degrees C. Upper and lower activation energies and transition temperatures were determined through the calculation of Arrhenius plot. Menhaden oil plus daily thyroxine injection resulted in higher and lower activation energies than the other treatments. This combined treatment also resulted in lower state 3 and higher state 4 respiration rates and tighter coupling of respiration to ATP synthesis. These effects were thought to be due to the effect this treatment combination had on membrane fluidity.

The Perceived Impact of Conflict on Adolescent Relationships.

ERIC Educational Resources Information Center

Laursen, Brett

1993-01-01

Examined adolescents' perceptions of their daily conflicts in relationships with mothers, fathers, siblings, friends, romantic partners, and other peers and adults. Most adolescent conflicts were perceived as benign events with few positive or negative consequences for the relationship. Results suggest that adolescents recognize the fluidity and…

Queering Black Racial Identity Development

ERIC Educational Resources Information Center

Johnson, Alandis A.; Quaye, Stephen John

2017-01-01

We used queer theory to encourage readers to think differently about previous theories about Black racial identity development. Queer theory facilitates new and deeper understandings of how Black people develop their racial identities, prompting more fluidity and nuance. Specifically, we present a queered model of Black racial identity development…

Active liquid-like behavior of nucleoli determines their size and shape in Xenopus laevis oocytes

PubMed Central

Brangwynne, Clifford P.; Mitchison, Timothy J.; Hyman, Anthony A.

2011-01-01

For most intracellular structures with larger than molecular dimensions, little is known about the connection between underlying molecular activities and higher order organization such as size and shape. Here, we show that both the size and shape of the amphibian oocyte nucleolus ultimately arise because nucleoli behave as liquid-like droplets of RNA and protein, exhibiting characteristic viscous fluid dynamics even on timescales of < 1 min. We use these dynamics to determine an apparent nucleolar viscosity, and we show that this viscosity is ATP-dependent, suggesting a role for active processes in fluidizing internal contents. Nucleolar surface tension and fluidity cause their restructuring into spherical droplets upon imposed mechanical deformations. Nucleoli exhibit a broad distribution of sizes with a characteristic power law, which we show is a consequence of spontaneous coalescence events. These results have implications for the function of nucleoli in ribosome subunit processing and provide a physical link between activity within a macromolecular assembly and its physical properties on larger length scales. PMID:21368180

Active liquid-like behavior of nucleoli determines their size and shape in Xenopus laevis oocytes.

PubMed

Brangwynne, Clifford P; Mitchison, Timothy J; Hyman, Anthony A

2011-03-15

For most intracellular structures with larger than molecular dimensions, little is known about the connection between underlying molecular activities and higher order organization such as size and shape. Here, we show that both the size and shape of the amphibian oocyte nucleolus ultimately arise because nucleoli behave as liquid-like droplets of RNA and protein, exhibiting characteristic viscous fluid dynamics even on timescales of < 1 min. We use these dynamics to determine an apparent nucleolar viscosity, and we show that this viscosity is ATP-dependent, suggesting a role for active processes in fluidizing internal contents. Nucleolar surface tension and fluidity cause their restructuring into spherical droplets upon imposed mechanical deformations. Nucleoli exhibit a broad distribution of sizes with a characteristic power law, which we show is a consequence of spontaneous coalescence events. These results have implications for the function of nucleoli in ribosome subunit processing and provide a physical link between activity within a macromolecular assembly and its physical properties on larger length scales.

DNA bending-induced phase transition of encapsidated genome in phage λ

PubMed Central

Lander, Gabriel C.; Johnson, John E.; Rau, Donald C.; Potter, Clinton S.; Carragher, Bridget; Evilevitch, Alex

2013-01-01

The DNA structure in phage capsids is determined by DNA–DNA interactions and bending energy. The effects of repulsive interactions on DNA interaxial distance were previously investigated, but not the effect of DNA bending on its structure in viral capsids. By varying packaged DNA length and through addition of spermine ions, we transform the interaction energy from net repulsive to net attractive. This allowed us to isolate the effect of bending on the resulting DNA structure. We used single particle cryo-electron microscopy reconstruction analysis to determine the interstrand spacing of double-stranded DNA encapsidated in phage λ capsids. The data reveal that stress and packing defects, both resulting from DNA bending in the capsid, are able to induce a long-range phase transition in the encapsidated DNA genome from a hexagonal to a cholesteric packing structure. This structural observation suggests significant changes in genome fluidity as a result of a phase transition affecting the rates of viral DNA ejection and packaging. PMID:23449219

Toward a Unified Science Curriculum.

ERIC Educational Resources Information Center

Showalter, Victor M.

The two major models of science curriculum change, textbook revision and national curriculum projects, are derived from, and reinforce, the present curriculum structure. This is undesirable in a time of increasing fluidity and change, because adaptation to new situations is difficult. Unified science, based on the premise that science is a unity,…

Intercultural Comparative Research: Rethinking Insider and Outsider Perspectives

ERIC Educational Resources Information Center

Kelly, Peter

2014-01-01

A commonsense problematic positions comparative researchers as either inside or outside cultures, or their situation is considered so as to acknowledge cultural fluidity and fragmentation. This article rejects the objectivism of these positions to provide a relational account. Using the lens of social practice theory, comparative pedagogy is…

Toward a Dialectical Model of Family Gender Discourse: Body, Identity, and Sexuality.

ERIC Educational Resources Information Center

Blume, Libby Balter; Blume, Thomas W.

2003-01-01

Proposes a dialectical model representing gender discourse in families. A brief review of literature in sociology, psychology, and gender studies focuses on three dialectical issues: nature versus culture, similarity versus difference, and stability versus fluidity. Deconstructing gender theories from a postmodern feminist perspective, the authors…

Being in Community: A Food Security Themed Approach to Public Scholarship

ERIC Educational Resources Information Center

Harrison, Barbara; Nelson, Connie; Stroink, Mirella

2013-01-01

For six years the Food Security Research Network at Lakehead University, Canada, has been engaged in an interdisciplinary theme-based service-learning initiative focusing on food security. Informed by complexity theory, the contextual fluidity partnership model brings community partners, students, and faculty into a nexus through which new…

You Sank My Lipid Rafts!

ERIC Educational Resources Information Center

Campbell, Tessa N.

2009-01-01

The plasma membrane is the membrane that serves as a boundary between the interior of a cell and its extracellular environment. Lipid rafts are microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids containing longer fatty acids. These domains are involved in many…

Metaphors of the Co-Taught Classroom.

ERIC Educational Resources Information Center

Adams, Lois; Cessna, Kay

1993-01-01

Discussions with exemplary Colorado general and special education coteachers led to development of three metaphors for the coteaching process: (1) yin and yang (the uniqueness and unity of the two teachers); (2) the dance (the rhythm, fluidity, and automaticity of effective collaboration); and (3) the particle and the stream (the thriving of…

Fruit metabolite networks in engineered and non-engineered tomato genotypes reveal fluidity in a hormone and agroecosystem specific manner

USDA-ARS?s Scientific Manuscript database

Multiple strategies have been explored throughout the world to meet food security. These include molecular breeding, transgenic genotype development, reduced-tillage crop production, modification of the soil environment with cover crops or polyethylene mulches and tunnels, and organic farming. Unde...

Thorns on My Tongue

ERIC Educational Resources Information Center

Reed, Malcolm

2012-01-01

How might we bear witness to the fluidity and fragility of identity work that takes place during classroom discussion? How do teachers and pupils play with the personal politics of positioning during our everyday interactions? The piece that follows is written as a story almost entirely in everyday dialogue. It takes a methodological turn towards…

Mind-Culture Interactions: How Writing Molds Mental Fluidity in Early Development

ERIC Educational Resources Information Center

Kazi, Smaragda; Demetriou, Andreas; Spanoudis, George; Zhang, Xiang Kui; Wang, Yuan

2012-01-01

This study investigated intellectual development in 4-7 years old Greek and Chinese children. They were examined on speeded performance, working memory, reasoning, and self-awareness tasks in order to investigate possible effects of learning the Chinese logographic system on possible differences in intellectual development between these ethnic…

Quantitative analysis of arm movement smoothness

NASA Astrophysics Data System (ADS)

Szczesna, Agnieszka; Błaszczyszyn, Monika

2017-07-01

The paper deals with the problem of motion data quantitative smoothness analysis. We investigated values of movement unit, fluidity and jerk for healthy and paralyzed arm of patients with hemiparesis after stroke. Patients were performing drinking task. To validate the approach, movement of 24 patients were captured using optical motion capture system.

Queer Youth in Family Therapy.

PubMed

Harvey, Rebecca G; Stone Fish, Linda

2015-09-01

Trends in popular belief about same-sex relationships have undergone noteworthy change in the United States over the last decade. Yet this change has been marked by stark polarizations and has occurred at varying rates depending upon regional, community, racial, religious, and individual family context. For queer youth and their families, this cultural transformation has broadened opportunities and created a new set of risks and vulnerabilities. At the same time, youth's increasingly open and playful gender fluidity and sexual identity is complicated by unique intersections of class, race, religion, and immigration. Effective family therapy with queer youth requires practitioner's and treatment models that are sensitive to those who bear the burden of multiple oppressions and the hidden resilience embedded in their layered identities. We present case examples of our model of family therapy which addresses refuge, supports difficult dialogs, and nurtures queerness by looking for hidden resilience in the unique intersections of queer youths' lives. These intersections provide transformational potential for youth, their families and even for family therapists as we are all nurtured and challenged to think more complexly about intersectionality, sexuality, and gender. © 2015 Family Process Institute.

Disruption of gel phase lipid packing efficiency by sucralose studied with merocyanine 540.

PubMed

Barker, Morgan; Kennedy, Anthony

2017-04-01

Sucralose, an artificial sweetener, displays very different behavior towards membranes than its synthetic precursor sucrose. The impact of both sugars on model dipalmitoylphosphatidylcholine model membranes was investigated using absorbance and flourescence spectroscopy and the membrane probe merocyanine 540. This probe molecule is highly sensitive to changes in membrane packing, microviscosity and polarity. This work focuses on the impact of sugars on the outer leaflet of unilamellar dipalmitoyl phosphatidylcholine model membranes. The choice of lipid permits access to the gel phase at room temperature and incorporation of the dye after liposome formation allows us to examine the direct impact of the sugar on the outer leaflet while maximizing the response of the dye to changes in the bilayer. The results demonstrate that sucrose has no impact on the packing efficiency of lipids in unilamellar DPPC vesicles in the gel phase. Conversely sucralose decreases the packing efficiency of lipids in the gel phase and results in decreased microviscosity and increased membrane fluidity, which may be as a result of water disruption at the membrane water interface. Copyright © 2017 Elsevier B.V. All rights reserved.

Pollock without Paint?

ERIC Educational Resources Information Center

Sutley, Jane

2011-01-01

This article describes how the author exposes her students to the world of Jackson Pollock, the artist who brings to mind dripping, meandering, splashing puddles of paint. Pollock's action paintings of the late 1940s-'50s call out for unfettered movement, fluidity, and freedom of application. Is it even possible to capture the action, rhythm and…

Afro-Caribbean International Students' Ethnic Identity Development: Fluidity, Intersectionality, Agency, and Performativity

ERIC Educational Resources Information Center

Malcolm, Zaria T.; Mendoza, Pilar

2014-01-01

Afro-Caribbean international students (ACIS) often become engrossed in a complex racial and ethnic dialogue wherein they are thrust into homogenous categorizations forcing them to negotiate their Afro-Caribbean self with other identities perceived by others such as African American, first- and second-generation Caribbean immigrant, African, and…

Influence of Changes in Water-to-Cement Ratio, Alkalinity, Concrete Fluidity, Voids, and Type of Reinforcing Steel on the Corrosion Potential of Steel in Concrete.

DOT National Transportation Integrated Search

2014-04-01

"Research on steel corrosion has demonstrated that the concentrations of chloride and hydroxide ion at the concrete/steel : interface influence the susceptibility of the steel to corrosive attack. This study used electrochemical means and changes in ...

Swimming Between: An Examination of the Inherent Complexity within Social Justice

ERIC Educational Resources Information Center

Aguilar, Israel; Nelson, Sarah; Niño, Juan Manuel

2016-01-01

Classrooms tend to be absolute spaces, places where fluidity is rejected and nearly everything--from people, to ideas, to practices and policies--is viewed and organized through binary logic. Because binary logic is implicitly accepted as the natural order in schools and the structures resulting from it are highly unmalleable, individuals who…

Exploring Embodied Methodologies for Transformative Practice in Early Childhood and Youth

ERIC Educational Resources Information Center

Cahill, Helen; Coffey, Julia; Smith, Kylie

2016-01-01

The development of gendered identities during early childhood and youth occurs in a context of "body culture" and the hyper-visibility of "perfect" bodies, which align with traditional gender ideals. Embodied methods can assist to make complexity more visible, and to allow participants to see fluidity, shifts, and becoming.…

"Change4Life for Your Kids": Embodied Collectives and Public Health Pedagogy

ERIC Educational Resources Information Center

Evans, Bethan; Colls, Rachel; Horschelmann, Kathrin

2011-01-01

Recent work in human geography has begun to explore the fluidity of bodily boundaries and to foreground the connectedness of bodies to other bodies/objects/places. Across multiple subdisciplinary areas, including health, children's and feminist geographies, geographers have begun to challenge the notion of a singular, bounded body by highlighting…

Higher lipophilic index indicates higher risk of coronary heart disease in postmenopausal women

USDA-ARS?s Scientific Manuscript database

Fatty acids are essential components of cell membranes and play an integral role in membrane fluidity. The lipophilic index (LI, defined as the sum of the products between fatty acid levels and melting points (degrees Celsius), divided by the total amount of fatty acids is thought to reflect membran...

Contesting Borders: A Challenge to Some Paradigmatic Assumptions of Intercultural and Comparative Education

ERIC Educational Resources Information Center

Bash, Leslie; Gundara, Jagdish

2012-01-01

Both intercultural education and comparative education have conventionally assumed the primacy of territoriality and sovereignty. This paper engages critically with these assumptions and, in turn, highlights the historical fluidity of nation states while seeking to normalise the process of geographical movement of populations. As such, a number of…

"A Writer More than . . . A Child": A Longitudinal Study Examining Adolescent Writer Identity

ERIC Educational Resources Information Center

Lammers, Jayne C.; Marsh, Valerie L.

2018-01-01

This article reconsiders theoretical claims of identity fluidity, stability, and agency through a longitudinal case study investigating one adolescent's writing over time and across spaces. Qualitative data spanning her four years of high school were collected and analyzed using a grounded theory approach with literacy-and-identity theory…

Queering Constructs: Proposing a Dynamic Gender and Sexuality Model

ERIC Educational Resources Information Center

Jourian, T. J.

2015-01-01

Higher education educators commonly understand social identities, including gender, to be fluid and dynamic. Lev's (2004) model of four components of sexual identity is commonly used to demonstrate the fluidity of sex, gender, and sexuality for individuals, but it does little to address the fixedness of those constructs. Through a multipronged…

State-Controlled Licensure and Interstate Mobility: Questions from Katrina

ERIC Educational Resources Information Center

Taylor, Carmen L.

2006-01-01

State licensure laws in speech-language pathology and audiology vary from state to state. Natural disaster displacements as well as trends in job mobility have increased the need for licensees to be able to have more fluidity in practicing from 1 state to another. Additionally, literature reviews on the history of professional licensure…

The Pharmacological Treatment of Depression in College Age Students: Some Principles and Precautions

ERIC Educational Resources Information Center

Blue, Howard C.; Sanfilippo, Louis C.; Young, Christopher M.

2007-01-01

College age students are in the midst of important psychosocial and neurobiological changes. The developmental fluidity of this period of life compels caution in diagnosing and treating depressive episodes, especially in discriminating between bipolar and non-bipolar depression. Treating college age students with depression requires adherence to…

In vivo collective cell migration requires an LPAR2-dependent increase in tissue fluidity.

PubMed

Kuriyama, Sei; Theveneau, Eric; Benedetto, Alexandre; Parsons, Maddy; Tanaka, Masamitsu; Charras, Guillaume; Kabla, Alexandre; Mayor, Roberto

2014-07-07

Collective cell migration (CCM) and epithelial-mesenchymal transition (EMT) are common to cancer and morphogenesis, and are often considered to be mutually exclusive in spite of the fact that many cancer and embryonic cells that have gone through EMT still cooperate to migrate collectively. Here we use neural crest (NC) cells to address the question of how cells that have down-regulated cell-cell adhesions can migrate collectively. NC cell dissociation relies on a qualitative and quantitative change of the cadherin repertoire. We found that the level of cell-cell adhesion is precisely regulated by internalization of N-cadherin downstream of lysophosphatidic acid (LPA) receptor 2. Rather than promoting the generation of single, fully mesenchymal cells, this reduction of membrane N-cadherin only triggers a partial mesenchymal phenotype. This intermediate phenotype is characterized by an increase in tissue fluidity akin to a solid-like-to-fluid-like transition. This change of plasticity allows cells to migrate under physical constraints without abolishing cell cooperation required for collectiveness. © 2014 Kuriyama et al.

Influence of lecithin-lipid composition on physico-chemical properties of nanoliposomes loaded with a hydrophobic molecule.

PubMed

Bouarab, Lynda; Maherani, Behnoush; Kheirolomoom, Azadeh; Hasan, Mahmoud; Aliakbarian, Bahar; Linder, Michel; Arab-Tehrany, Elmira

2014-03-01

In this work, we studied the effect of nanoliposome composition based on phospholipids of docosahexaenoic acid (PL-DHA), salmon and soya lecithin, on physico-chemical characterization of vector. Cinnamic acid was encapsulated as a hydrophobic molecule in nanoliposomes made of three different lipid sources. The aim was to evaluate the influence of membrane lipid structure and composition on entrapment efficiency and membrane permeability of cinnamic acid. These properties are important for active molecule delivery. In addition, size, electrophoretic mobility, phase transition temperature, elasticity and membrane fluidity were measured before and after encapsulation. The results showed a correlation between the size of the nanoliposome and the entrapment. The entrapment efficiency of cinnamic acid was found to be the highest in liposomes prepared from salmon lecithin. The nanoliposomes composed of salmon lecithin presented higher capabilities as a carrier for cinnamic acid encapsulation. These vesicles also showed a high stability which in turn increases the membrane rigidity of nanoliposome as evaluated by their elastic properties, membrane fluidity and phase transition temperature. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced fluidity liquid chromatography of inulin fructans using ternary solvent strength and selectivity gradients.

PubMed

Bennett, Raffeal; Olesik, Susan V

2018-01-25

The value of exploring selectivity and solvent strength ternary gradients in enhanced fluidity liquid chromatography (EFLC) is demonstrated for the separation of inulin-type fructans from chicory. Commercial binary pump systems for supercritical fluid chromatography only allow for the implementation of ternary solvent strength gradients which can be restrictive for the separation of polar polymeric analytes. In this work, a custom system was designed to extend the capability of EFLC to allow tuning of selectivity or solvent strength in ternary gradients. Gradient profiles were evaluated using the Berridge function (RF 1 ), normalized resolution product (NRP), and gradient peak capacity (P c ). Selectivity gradients provided the separation of more analytes over time. The RF 1 function showed favor to selectivity gradients with comparable P c to that of solvent strength gradients. NRP did not strongly correlate with P c or RF 1 score. EFLC with the hydrophilic interaction chromatography, HILIC, separation mode was successfully employed to separate up to 47 fructan analytes in less than 25 min using a selectivity gradient. Copyright © 2017 Elsevier B.V. All rights reserved.

The Extent and Nature of Fluidity in Typologies of Female Sex Work in Southern India: Implications for HIV Prevention Programs

PubMed Central

Saggurti, Niranjan

2012-01-01

These authors examine the nature and extent of fluidity in defining the typology of female sex work based on the place of solicitation or place of sex or both places together, and whether sex workers belonging to a particular typology are at increased risk of HIV in southern India. Data are drawn from a cross-sectional survey conducted during 2007–2008 among mobile female sex workers (N = 5301) in four Indian states. Findings from this study address an important policy issue: Should programmatic prevention interventions be spread to cover all places of sex work or be focused on a few places that cover a large majority of sex workers? Results indicate that most female sex workers, including those who are usually hard to reach such as those who are mobile or who use homes for soliciting clients or sex, can be reached programmatically multiple times by concentrating on a smaller number of categories, such as street-, lodge-, and brothel-based sex workers. PMID:22745597

Fatty acids rehabilitated long-term neurodegenerative: like symptoms in olfactory bulbectomized rats.

PubMed

Yehuda, Shlomo; Rabinovitz, Sharon

2015-05-01

Our previous study demonstrated that an olfactory bulbectomy in rats induced short-term, multifaceted, devastating Alzheimer's-like effects, which included cognitive impairment, hyperactivity, hyperthermia, and increased levels of homocysteine and pro-inflammatory cytokines, including IL-17A. In addition, the rats exhibited an increase in the hyperphosphorylation of brain Tau proteins and in the number of neurofibrillary tangles. Here, we examined the long-term effects of the surgery and found that olfactory bulbectomy also rendered the rats to become anemic with brain iron overload. Additionally, a significant reduction in the membrane fluidity index in frontal cortex synaptosomes was found. Treatment with a mixture of n - 3/n - 6 of fatty acids restored the unwanted effect. The beneficial effects of fatty acids are mediated via the effects of fatty acids on the neuronal membrane structure and fluidity. These findings are similar to Alzheimer's symptoms, which suggest this model can be used as an animal model for Alzheimer's disease. We recommend using this model to scan potential new anti-Alzheimer's drugs.

On the possibility to affect the course of glycaemia, insulinaemia, and perceived hunger/satiety to bread meals in healthy volunteers.

PubMed

Ekström, Linda M N K; Björck, Inger M E; Ostman, Elin M

2013-04-25

Frequent hyperglycaemia is associated with oxidative stress and subclinical inflammation, and thus increased risk of cardiovascular disease. Possibilities of modulating glycaemia, insulinaemia and perceived satiety for bread products were investigated, with emphasis on the course of glycaemia expressed as a glycaemic profile (defined as the duration of the glucose curve above the fasting concentration divided by the incremental glucose peak). For this purpose white wheat bread was supplemented with whole grain corn flour with an elevated amylose content and different types and levels of guar gum. The bread products were characterised in vitro for release of starch degradation products and content of resistant starch. Fibre related fluidity following enzyme hydrolysis was also studied. By combining medium weight guar gum and whole grain corn flour with an elevated amylose content, the course of glycaemia, insulinaemia and subjective appetite ratings were improved compared to the reference white wheat bread. In addition, the combination beneficially influenced the content of resistant starch. Fluidity measurements showed potential to predict the glycaemic profile.

Protein separations using enhanced-fluidity liquid chromatography.

PubMed

Bennett, Raffeal; Olesik, Susan V

2017-11-10

Enhanced-fluidity liquid chromatography (EFLC) methods using methanol/H 2 O/CO 2 and hydrophilic interaction liquid chromatography (HILIC) were explored for the separation of proteins and peptides. EFLC is a separation mode that uses a mobile phase made of conventional solvents combined with liquid carbon dioxide (CO 2 ) in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis. TFA additive and elevated temperature were leveraged as key factors in the separation of a 13-analyte intact protein mixture in under 5min. Under these conditions EFLC showed modest improvement in terms of peak asymmetry and analysis time over the competing ACN/H 2 O separation. Protein analytes detected by electrospray ionization - quadrupole time of flight, were shown to be unaffected by the addition of CO 2 in the mobile phase. Herein, the feasibility of separating hydrophilic proteins up to 80kDa (with transferrin) is demonstrated for CO 2 -containing mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Short branched-chain C6 carboxylic acids result in increased growth, novel 'unnatural' fatty acids and increased membrane fluidity in a Listeria monocytogenes branched-chain fatty acid-deficient mutant.

PubMed

Sen, Suranjana; Sirobhushanam, Sirisha; Hantak, Michael P; Lawrence, Peter; Brenna, J Thomas; Gatto, Craig; Wilkinson, Brian J

2015-10-01

Listeria monocytogenes is a psychrotolerant food borne pathogen, responsible for the high fatality disease listeriosis, and expensive food product recalls. Branched-chain fatty acids (BCFAs) of the membrane play a critical role in providing appropriate membrane fluidity and optimum membrane biophysics. The fatty acid composition of a BCFA-deficient mutant is characterized by high amounts of straight-chain fatty acids and even-numbered iso fatty acids, in contrast to the parent strain where odd-numbered anteiso fatty acids predominate. The presence of 2-methylbutyrate (C5) stimulated growth of the mutant at 37°C and restored growth at 10°C along with the content of odd-numbered anteiso fatty acids. The C6 branched-chain carboxylic acids 2-ethylbutyrate and 2-methylpentanoate also stimulated growth to a similar extent as 2-methylbutyrate. However, 3-methylpentanoate was ineffective in rescuing growth. 2-Ethylbutyrate and 2-methylpentanoate led to novel major fatty acids in the lipid profile of the membrane that were identified as 12-ethyltetradecanoic acid and 12-methylpentadecanoic acid respectively. Membrane anisotropy studies indicated that growth of strain MOR401 in the presence of these precursors increased its membrane fluidity to levels of the wild type. Cells supplemented with 2-methylpentanoate or 2-ethylbutyrate at 10°C shortened the chain length of novel fatty acids, thus showing homeoviscous adaptation. These experiments use the mutant as a tool to modulate the membrane fatty acid compositions through synthetic precursor supplementation, and show how existing enzymes in L. monocytogenes adapt to exhibit non-native activity yielding unique 'unnatural' fatty acid molecules, which nevertheless possess the correct biophysical properties for proper membrane function in the BCFA-deficient mutant. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiphase flow modelling of explosive volcanic eruptions using adaptive unstructured meshes

NASA Astrophysics Data System (ADS)

Jacobs, Christian T.; Collins, Gareth S.; Piggott, Matthew D.; Kramer, Stephan C.

2014-05-01

Explosive volcanic eruptions generate highly energetic plumes of hot gas and ash particles that produce diagnostic deposits and pose an extreme environmental hazard. The formation, dispersion and collapse of these volcanic plumes are complex multiscale processes that are extremely challenging to simulate numerically. Accurate description of particle and droplet aggregation, movement and settling requires a model capable of capturing the dynamics on a range of scales (from cm to km) and a model that can correctly describe the important multiphase interactions that take place. However, even the most advanced models of eruption dynamics to date are restricted by the fixed mesh-based approaches that they employ. The research presented herein describes the development of a compressible multiphase flow model within Fluidity, a combined finite element / control volume computational fluid dynamics (CFD) code, for the study of explosive volcanic eruptions. Fluidity adopts a state-of-the-art adaptive unstructured mesh-based approach to discretise the domain and focus numerical resolution only in areas important to the dynamics, while decreasing resolution where it is not needed as a simulation progresses. This allows the accurate but economical representation of the flow dynamics throughout time, and potentially allows large multi-scale problems to become tractable in complex 3D domains. The multiphase flow model is verified with the method of manufactured solutions, and validated by simulating published gas-solid shock tube experiments and comparing the numerical results against pressure gauge data. The application of the model considers an idealised 7 km by 7 km domain in which the violent eruption of hot gas and volcanic ash high into the atmosphere is simulated. Although the simulations do not correspond to a particular eruption case study, the key flow features observed in a typical explosive eruption event are successfully captured. These include a shock wave resulting from the sudden high-velocity inflow of gas and ash; the formation of a particle-laden plume rising several hundred metres into the atmosphere; the eventual collapse of the plume which generates a volcanic ash fountain and a fast ground-hugging pyroclastic density current; and the growth of a dilute convective region that rises above the ash fountain as a result of buoyancy effects. The results from Fluidity are also compared with results from MFIX, a fixed structured mesh-based multiphase flow code, that uses the same set-up. The key flow features are also captured in MFIX, providing at least some confidence in the plausibility of the numerical results in the absence of quantitative field data. Finally, it is shown by a convergence analysis that Fluidity offers the same solution accuracy for reduced computational cost using an adaptive mesh, compared to the same simulation performed with a uniform fixed mesh.

[Effects of ursodeoxycholic acid on the liver plasma membrane fluidity, hepatic glutathione concentration, hepatic estrogen receptors and progesterone receptors in pregnant rats with ethinylestradiol and progesterone induced intrahepatic cholestasis].

PubMed

Shi, Qing-yun; Kong, Bei-hua; Ma, Kai-dong; Zhang, Xiang-li; Jiang, Sen

2003-11-01

To explore the effects of ursodeoxycholic acid (UDCA) on the fluidity of hepatic plasma membrane, glutathione concentration in liver, hepatic estrogen receptors and progesterone receptors in pregnant rats with ethinylestradiol and progesterone induced intrahepatic cholestasis. sixty clean SD pregnant rats were selected and divided into three groups at random. Since the 13th day of pregnancy after taking blood, normal group was injected subcutaneously with refined vegetable oil 2.5 ml x kg(-1) x d(-1). Control group and treatment group were injected subcutaneously with the solution of progesterone 75 mg x kg(-1) x d(-1) and 17-alpha-ethynylestradio 1.25 mg x kg(-1) x d(-1) till the 17th day. Since the 17th day control group, normal group were fedwish 0.9% natriichloridi solution 5 ml x kg(-1) x d(-1); Treatment group was fedwish UDCA 50 mg x kg(-1) x d(-1) every day. On the 21th day, all rats were killed. Then the livers were collected for study. Membrane fluidity was measured by fluorescence polarization using 1,6-diphenyl-1,3,5-hexatriene (DPH) as a probe. Glutathione concentration was measured by 5,5'-dithionbis (2-nitrobenzoic acid) (DTNB). Estrogen receptors and progesterone receptors were measured by flow cytometry. (1) Hepatic plasma membrane fluidity and glutathione (GSH) concentration: significantly lower level of GSH concentration and higher fluorescence polarization (P) were detected in control group (GSH: 1.13 +/- 0.03, P: 0.149 +/- 0.008) in comparison with normal group (GSH: 2.11 +/- 0.07, P: 0.132 +/- 0.004, P < 0.05). However, Significantly higher level of GSH concentration and lower fluorescence polarization were detected in treatment group (GSH: 1.82 +/- 0.04, P: 0.141 +/- 0.006) in comparison with control group (P < 0.05). The level of GSH concentration and fluorescence polarization were no difference between treatment group and normal group. Hepatic estrogen receptors (ER) and progesterone receptors (PR): The expression of ER and PR in control group (ER: 89.4 +/- 8.4, PR: 112.3 +/- 11.6) were higher than that of other two groups (P < 0.05). The expression of ER and PR in treatment group (ER: 56.4 +/- 7.5, PR: 70.1 +/- 9.3) were lower than that of control group (P < 0.05). But there was no difference between treatment group and normal group (ER: 39.5 +/- 7.3, PR: 59.6 +/- 7.4; P > 0.05). Ursodeoxycholic acid may be effective drug in treatment intrahepatic cholestasis of pregnancy.

The Multi/Plural Turn, Postcolonial Theory, and Neoliberal Multiculturalism: Complicities and Implications for Applied Linguistics

ERIC Educational Resources Information Center

Kubota, Ryuko

2016-01-01

In applied linguistics and language education, an increased focus has been placed on plurality and hybridity to challenge monolingualism, the native speaker norm, and the modernist view of language and language use as unitary and bounded. The multi/plural turn parallels postcolonial theory in that they both support hybridity and fluidity while…

Thermal Regulation of Membrane Lipid Fluidity by a Two-Component System in "Bacillus Subtilis"

ERIC Educational Resources Information Center

Bredeston, L. M.; Marciano, D.; Albanesi, D.; De Mendoza, D.; Delfino, J. M.

2011-01-01

This article describes a simple and robust laboratory exercise on the regulation of membrane unsaturated fatty acid composition in bacteria by a decrease in growth temperature. We take advantage of the well characterized Des pathway of "Bacillus subtilis", composed of a [delta]5-desaturase (encoded by the "des" gene) and the canonical…

76 FR 27156 - Bureau of Educational and Cultural Affairs (ECA) Request for Grant Proposals; Teacher Exchange...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-10

... fluidity and synergy. The international teachers gain an in-depth understanding of U.S. schools... implementation at host universities and schools. International teachers in the U.S. for a semester audit two... 2013 to visit the home schools of selected international teacher alumni, to develop lesson plans on...

Combined Diffusion Tensor Imaging and Transverse Relaxometry in Early-Onset Bipolar Disorder

ERIC Educational Resources Information Center

Gonenc, Atilla; Frazier, Jean A.; Crowley, David J.; Moore, Constance M.

2010-01-01

Objective: Transverse relaxation time (T2) imaging provides the opportunity to examine membrane fluidity, which can affect a number of cellular functions. The objective of the present work was to examine T2 abnormalities in children with unmodified DSM-IV-TR bipolar disorder (BD) in bilateral cingulate-paracingulate (CPC) white matter. Method: A…

Exploring the Adolescent's Creative Pathways: Mindfulness, Role Fluidity, Story, and the Dramatic Curriculum

ERIC Educational Resources Information Center

McNees, David

2015-01-01

David McNees' deep foray into creativity theory and drama begins with mindfulness as a preparation for adolescent focus. This article discusses role incarnation, the correlation of the three-period lesson to Landy's role theory, the creation and re-creation of personal story and identity, archetypal heroes, and how the adaptability learned in…

The Complexities of Adolescent Dating and Sexual Relationships: Fluidity, Meaning(s), and Implications for Young Adults' Well-Being

ERIC Educational Resources Information Center

Manning, Wendy D.; Longmore, Monica A.; Copp, Jennifer; Giordano, Peggy C.

2014-01-01

The complexity of adolescents' dating and sexual lives is not easily operationalized with simple indicators of dating or sexual activity. While building on prior work that emphasizes the "risky" nature of adolescents' intimate relationships, we assess whether a variety of indicators reflecting the complexity of…

Symposium: "Crash": Rhetorically Wrecking Discourses of Race, Tolerance, and White Privilege

ERIC Educational Resources Information Center

Nunley, Vorris L.

2007-01-01

From within the milieu of race and identity fatigue emerges "Crash." Winner of three Academy Awards, including Best Picture, "Crash" addresses how the fluidity of identity is pooled, ebbed, blocked, directed, dammed up. How identity and subjectivity are dammed up and mediated through the force of the anxieties, fears, and frustrations of people…

The VLE as a Trojan Mouse: Policy, Politics and Pragmatism

ERIC Educational Resources Information Center

Brown, Mark; Paewai, Shelley; Suddaby, Gordon

2010-01-01

This paper argues that selecting a new Learning Management System (LMS) is a strategic decision about the future direction of your institution. However, the development of a robust methodology for the selection of a new LMS is particularly challenging given the fluidity of the e-learning environment. This is especially so when both quantitative…

Silybum marianum oil attenuates oxidative stress and ameliorates mitochondrial dysfunction in mice treated with D-galactose

PubMed Central

Zhu, Shu Yun; Dong, Ying; Tu, Jie; Zhou, Yue; Zhou, Xing Hua; Xu, Bin

2014-01-01

Background: Silybum marianum has been used as herbal medicine for the treatment of liver disease, liver cirrhosis, and to prevent liver cancer in Europe and Asia since ancient times. Silybum marianum oil (SMO), a by-product of silymarin production, is rich in essential fatty acids, phospholipids, sterols, and vitamin E. However, it has not been very good development and use. Objective: In the present study, we used olive oil as a control to investigate the antioxidant and anti-aging effect of SMO in D-galactose (D-gal)-induced aging mice. Materials and Methods: D-gal was injected intraperitoneally (500 mg/kg body weight daily) for 7 weeks while SMO was simultaneously administered orally. The triglycerides (TRIG) and cholesterol (CHOL) levels were estimated in the serum. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), monoamine oxidase (MAO), malondialdehyde (MDA), caspase-3, and Bcl-2 were determined in the liver and brain. The activities of Na+-K+-adenosine triphosphatase (ATPase), Ca2+-Mg2+-ATPase, membrane potential (ΔΨm), and membrane fluidity of the liver mitochondrial were estimated. Results: SMO decreased levels of TRIG and CHOL in aging mice. SMO administration elevated the activities of SOD, GSH-Px, and T-AOC, which are suppressed by aging. The levels of MAO and MDA in the liver and brain were reduced by SMO administration in aging mice. Enzyme linked immunosorbent assay showed that SMO significantly decreased the concentration of caspase-3 and improved the activity of Bcl-2 in the liver and brain of aging mice. Furthermore, SMO significantly attenuated the D-gal induced liver mitochondrial dysfunction by improving the activities of Na+-K+-ATPase, Ca2+-Mg2+-ATPase, membrane potential (ΔΨm), and membrane fluidity. Conclusion: These results indicate that SMO effectively attenuated oxidative damage and improved apoptosis related factors as well as liver mitochondrial dysfunction in aging mice. PMID:24914315

Seminal plasma applied post-thawing affects boar sperm physiology: a flow cytometry study.

PubMed

Fernández-Gago, Rocío; Domínguez, Juan Carlos; Martínez-Pastor, Felipe

2013-09-01

Cryopreservation induces extensive biophysical and biochemical changes in the sperm. In the present study, we used flow cytometry to assess the capacitation-like status of frozen-thawed boar spermatozoa and its relationship with intracellular calcium, assessment of membrane fluidity, modification of thiol groups in plasma membrane proteins, reactive oxygen species (ROS) levels, viability, acrosomal status, and mitochondrial activity. This experiment was performed to verify the effect of adding seminal plasma on post-thaw sperm functions. To determine these effects after cryopreservation, frozen-thawed semen from seven boars was examined after supplementation with different concentrations of pooled seminal plasma (0%, 10%, and 50%) at various times of incubation from 0 to 4 hours. Incubation caused a decrease in membrane integrity and an increase in acrosomal damage, with small changes in other parameters (P > 0.05). Although 10% seminal plasma showed few differences with 0% (ROS increase at 4 hours, P < 0.05), 50% seminal plasma caused important changes. Membrane fluidity increased considerably from the beginning of the experiment, and ROS and free thiols in the cell surface increased by 2 hours of incubation. By the end of the experiment, viability decreased and acrosomal damage increased in the 50% seminal plasma samples. The addition of 50% of seminal plasma seems to modify the physiology of thawed boar spermatozoa, possibly through membrane changes and ROS increase. Although some effects were detrimental, the stimulatory effect of 50% seminal plasma could favor the performance of post-thawed boar semen, as showed in the field (García JC, Domínguez JC, Peña FJ, Alegre B, Gonzalez R, Castro MJ, Habing GG, Kirkwood RN. Thawing boar semen in the presence of seminal plasma: effects on sperm quality and fertility. Anim Reprod Sci 2010;119:160-5). Copyright © 2013 Elsevier Inc. All rights reserved.

The fluidity of blood in African elephants (Loxodonta africana).

PubMed

Windberger, U; Plasenzotti, R; Voracek, Th

2005-01-01

The large cellular volume of erythrocytes and the increased plasma concentration of proteins in elephants are factors which potentially affect blood rheology adversely. To verify blood rheology, routine hemorheologic variables were analyzed in four African elephants (Loxodonta africana), housed in the zoo of Vienna. Whole blood viscosity at three different shear rates (WBV at low shear rate: WBV 0.7 s(-1) and WBV 2.4 s(-1); WBV at high shear rate: WBV 94 s(-1) done by LS30, Contraves) and erythrocyte aggregation (aggregation indices AI by LS30; aggregation indices M0, M1 by Myrenne aggregometer) were high (WBV 94 s(-1): 5.368 (5.246/5.648); WBV 2.4 s(-1): 16.291 (15.605/17.629); WBV 0.7 s(-1): 28.28 (25.537/32.173) mPa s; AI 2.4 s(-1): 0.25 (0.23/0.30); AI 0.7 s(-1): 0.24 (0.23/0.28); M0: 7.8 (6.4/8.4); M1: 30.2 (25/31)). Plasma viscosity (PV) was increased as well (1.865 (1.857/1.912) mPa s) compared to other mammalian species. These parameters would indicate a decrease in blood fluidity in elephants. However, erythrocyte rigidity (LORCA, Mechatronics) was decreased, which in contrast, has a promotive effect on peripheral perfusion. Blood rheology of the elephants was determined by a high whole blood and plasma viscosity as the result of pronounced erythrocyte aggregation and high plasma protein concentration. Thus, in the terminal vessels the resistance to flow will be increased. The large erythrocytes, which might impede blood flow further due to geometrical reasons, however, had a pronounced flexibility. We conclude that the effect of the increased inner resistance to peripheral blood flow was counteracted by the decreased rigidity of the erythrocytes to enable an adequate blood flow in African elephants.

Quality Assessment of A356 Ingots from Different Suppliers in Wheel Production

NASA Astrophysics Data System (ADS)

Koca, Emre; Yuksel, Caglar; Erzi, Eray; Dışpınar, Derya

In a typical foundry floor, several precautions are taken prior to the casting in order to achieve pore-free, high quality parts. In low pressure die castings, these operations involve runner design, pressure adjustment, die temperature selection, cooling locations etc. For the melt, it is important to determine the degassing duration and gas flow rate. In addition, the period of modification (Ti, Sr) addition also plays a significant role. Even after optimization of all these parameters, reject parts can still be found. What has always been disregarded is the quality assessment of the ingot suppliers. Therefore, in this work, four different A356 ingot provider's quality has been investigated in the wheel producer company. Reduced pressure test was used to quantify melt quality by means of bifilm index measurement. In addition, fluidity, feedability and tensile tests have been carried out. The rejection rates were compared according to provider's quality level.

Interaction of Impulsive Pressures of Cavitation Bubbles with Cell Membranes during Sonoporation

NASA Astrophysics Data System (ADS)

Kodama, Tetsuya; Koshiyama, Ken-ichiro; Tomita, Yukio; Suzuki, Maiko; Yano, Takeru; Fujikawa, Shigeo

2006-05-01

Ultrasound contrast agents (UCAs), are capable of enhancing non-invasive cytoplasmic molecular delivery in the presence of ultrasound. Collapse of UCAs may generate nano-scale cavitation bubbles, resulting in the transient permeabilization of the cell membrane. In the present study, we investigated the interaction of a cavitation bubble-induced shock wave with a cell membrane using acoustic theory and molecular dynamics (MD) simulation. From the theory, we obtained the shock wave propagation distance from the center of a cavitation bubble that would induce membrane damage. The MD simulation determined the relationship between the uptake of water molecules into the lipid bilayer and the shock wave. The interaction of the shock wave induced a structural change of the bilayer and subsequently increased the fluidity of each molecule. These changes in the bilayer due to shock waves may be an important factor in the use of UCAs to produce the transient membrane permeability during sonoporation.

Synthetic peptides corresponding to human follicle-stimulating hormone (hFSH)-beta-(1-15) and hFSH-beta-(51-65) induce uptake of 45Ca++ by liposomes: evidence for calcium-conducting transmembrane channel formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grasso, P.; Santa-Coloma, T.A.; Reichert, L.E. Jr.

1991-06-01

We have previously described FSH receptor-mediated influx of 45Ca++ in cultured Sertoli cells from immature rats and receptor-enriched proteoliposomes via activation of voltage-sensitive and voltage-independent calcium channels. We have further shown that this effect of FSH does not require cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding protein or activation of adenylate cyclase. In the present study, we have identified regions of human FSH-beta-subunit which appear to be involved in mediating calcium influx. We screened 11 overlapping peptide amides representing the entire primary structure of hFSH-beta-subunit for their effects on 45Ca++ flux in FSH receptor-enriched proteoliposomes. hFSH-beta-(1-15) and hFSH-beta-(51-65) inducedmore » uptake of 45Ca++ in a concentration-related manner. This effect of hFSH-beta-(1-15) and hFSH-beta-(51-65) was also observed in liposomes lacking incorporated FSH receptor. Reducing membrane fluidity by incubating liposomes (containing no receptor) with hFSH-beta-(1-15) or hFSH-beta-(51-65) at temperatures lower than the transition temperatures of their constituent phospholipids resulted in no significant (P greater than 0.05) difference in 45Ca++ uptake. The effectiveness of the calcium ionophore A23187, however, was abolished. Ruthenium red, a voltage-independent calcium channel antagonist, was able to completely block uptake of 45Ca++ induced by hFSH-beta-(1-15) and hFSH-beta-(51-65) whereas nifedipine, a calcium channel blocker specific for L-type voltage-sensitive calcium channels, was without effect. These results suggest that in addition to its effect on voltage-sensitive calcium channel activity, interaction of FSH with its receptor may induce formation of transmembrane aqueous channels which also facilitate influx of extracellular calcium.« less

Determination of fatty acid profile in ram spermatozoa and seminal plasma.

PubMed

Díaz, R; Torres, M A; Bravo, S; Sanchez, R; Sepúlveda, N

2016-08-01

Fatty acids are important in male reproductive function because they are associated with membrane fluidity, acrosome reaction, sperm motility and viability, but limited information exists about the fatty acid profile of ram semen. Our aim was to determine the fatty acid composition in ram spermatozoa and seminal plasma. Sixty ejaculates were obtained from three ram (20 ejaculates/ram) using artificial vagina. Ram spermatozoa (RS) and seminal plasma (SP) were separated using centrifugation, and the fatty acids were analysed by gas chromatography. Total lipids obtained in ram spermatozoa were 1.8% and 1.6% in seminal plasma. Saturated fatty acid (SFA) was proportionally major in SP (66.6%) that RS (49.9%). The highest proportions of SFA corresponded to C4:0 (RS = 16.3% and SP = 28.8%) and C16:0 (RS = 16.3% and PS = 20%). The most important unsaturated fatty acid (UFA) was docosahexaenoic acid (DHA), 44.9% in RS and 31.5% in SP. The profile of fatty acid and their proportions showed differences between spermatozoa and seminal plasma. © 2015 Blackwell Verlag GmbH.

"If Only I Did Not Have That Label Attached to Me": Foregrounding Self-Positioning and Intersectionality in the Experiences of Immigrant and Refugee Youth

ERIC Educational Resources Information Center

Fruja Amthor, Ramona

2017-01-01

In order to bring forth the specific intricacies of the migration experience among comparatively understudied immigrant and refugee youth, this article bridges an intersectionality framework with multicultural education scholars' calls to flexibility and fluidity in conceptualizing culture and identity. Drawing on in-depth interviews, the analysis…

The Contribution of Aboriginal Epistemologies to Mathematics Education in Australia: Exploring the Silences

ERIC Educational Resources Information Center

Hughes, Amber; Laura, Ron

2018-01-01

Epistemology is a conceptual template for how we think about the world, and the study of how we come to know the world around us. The world does not dictate unequivocally how to interpret it. This article will explore this position on the fluidity of epistemic constructs through two prominent philosophical perspectives, those being derived from…

A Ratchet Lens: Black Queer Youth, Agency, Hip Hop, and the Black Ratchet Imagination

ERIC Educational Resources Information Center

Love, Bettina L.

2017-01-01

This article explores the utilization of the theory of a Black ratchet imagination as a methodological perspective to examine the multiple intersections of Black and queer identity constructions within the space of hip hop. In particular, I argue for the need of a methodological lens that recognizes, appreciates, and struggles with the fluidity,…

I'm Deleting as Fast as I Can: Negotiating Learning Practices in Cyberspace

ERIC Educational Resources Information Center

Thompson, Terrie Lynn

2012-01-01

Learning in and through work is one of the many spaces in which pedagogy may unfold. Web technologies amplify this fluidity and online learning now encompasses a plethora of practices. In this paper I focus on the delete button and deleting practices of self-employed workers engaged in informal work-related learning in online communities. How the…

Controlling Protein Conformation and Activities on Block-Copolymer Nanopatterns

DTIC Science & Technology

2013-10-24

adsorption: the need for large stick pads! Average area = 2.4±1.5x104 nm2 Average area = 7.9±4.7x104 nm2 ~14 nm2 ~56 nm2 ~350 nm2 Kinetic...Fluidity in multivalent interactions Pre-clustering - “ sweet spot” Dynamic- clustering Label free lipid bilayer arrays with SPR The dark area

Will Global Warming Cause a Rise in Sea Level? A Simple Activity about the States of Water

ERIC Educational Resources Information Center

Oguz, Ayse

2009-01-01

In this activity, a possible problem related to global warming is clarified by the principle of states of water. The activity consists of an experiment that includes three scientific principles: Archimedes' Principle, the Law of Conservation of Matter, and the fluidity of liquids. The experiment helps students raise questions and open new horizons…

Adventures with Text and Beyond: Education for Empowerment--The Link between Multiple Literacies and Critical Consciousness.

ERIC Educational Resources Information Center

Hubbard, Scott

2013-01-01

For students who sense no fluidity between their academic context and their personal contexts, what's at stake is more than just their scholastic achievement--rather, their development as individual agents who exist in larger social and historical contexts is jeopardized. When teachers and schools neglect to recognize the legitimacy of…

Ambivalence and Fluidity in the Teenage Smoking and Quitting Experience: Lessons from a Qualitative Study at an English Secondary School

ERIC Educational Resources Information Center

Buswell, Marina; Duncan, Peter

2013-01-01

Objective: To evaluate a school-based stop smoking pilot project and to understand the teenage experience of smoking and quitting within that context. Design: Flexible design methods. Setting: A Kent (United Kingdom [UK]) secondary school. Methods: Semi-structured interviews analyzed following a grounded theory approach. Results: The main themes…

Youth Participatory Action Research (YPAR) 2.0: How Technological Innovation and Digital Organizing Sparked a Food Revolution in East Oakland

ERIC Educational Resources Information Center

Akom, Antwi; Shah, Aekta; Nakai, Aaron; Cruz, Tessa

2016-01-01

This article argues that technological innovation is transforming the flow of information, the fluidity of social action, and is giving birth to new forms of bottom up innovation that are capable of expanding and exploding old theories of reproduction and resistance because "smart mobs," "street knowledge," and "social…

Omega-3 Fatty Acid Supplementation for the Treatment of Children with Attention-Deficit/Hyperactivity Disorder Symptomatology: Systematic Review and Meta-Analysis

ERIC Educational Resources Information Center

Bloch, Michael H.; Qawasmi, Ahmad

2011-01-01

Objective: Several studies have demonstrated differences in omega-3 fatty acid composition in plasma and in erythrocyte membranes in patients with attention-deficit/hyperactivity disorder (ADHD) compared with unaffected controls. Omega-3 fatty acids have anti-inflammatory properties and can alter central nervous system cell membrane fluidity and…

Fluidity in the Networked Society--Self-Initiated learning as a Digital Literacy Competence

ERIC Educational Resources Information Center

Levinsen, Karin Tweddell

2011-01-01

In the globalized economies e-permeation has become a basic condition in our everyday lives. ICT can no longer be understood solely as artefacts and tools and computer-related literacy are no longer restricted to the ability to operate digital tools for specific purposes. The network society, and therefore also eLearning are characterized by…

Dimensions of somatization and hypochondriasis.

PubMed

Ford, C V

1995-05-01

A significantly large group of patients who communicate their psychosocial distress in the form of physical symptoms are called somatizers. They tend to overuse medical services. The syndromes with which they present have indistinct boundaries, and there tends to be some fluidity of their symptomatic presentations. Underlying psychiatric disorders such as mood disorders, anxiety disorders (including obsessive compulsive disorder), and personality disorders are frequently present.

A New Destination for "The Flying Bus"?: The Implications of Orlando-Rican Migration for Luis Rafael Sanchez's "La guagua aerea"

ERIC Educational Resources Information Center

Barreneche, Gabriel Ignacio; Lombardi, Jane; Ramos-Flores, Hector

2012-01-01

Puerto Rican author Luis Rafael Sanchez's "La guagua aerea" explores the duality, hybridity, and fluidity of US-Puerto Rican identity through the frequent travel of migrants between New York City (the traditional destination city for Puerto Rican migrants) and the island. In recent years, however, the "flying bus" has adopted a…

Performances and working mechanism of a novel polycarboxylate superplasticizer synthesized through changing molecular topological structure.

PubMed

Liu, Xiao; Guan, Jianan; Lai, Guanghong; Wang, Ziming; Zhu, Jie; Cui, Suping; Lan, Mingzhang; Li, Huiqun

2017-10-15

A novel star-shaped polycarboxylate superplasticizer (SPCE) was synthesized through a simple two-step method. 1 H Nuclear Magnetic Resonance ( 1 H NMR) and Infrared Spectroscopy (IR) measurements were used for structural characterization. SPCE and comb-shaped polycarboxylate superplasticizer (CPCE) with same molecular weights were designed and synthesized. The cement paste containing SPCE exhibited better fluidity, fluidity retention, water reduction, 25% lower saturated dosage of PCE, 10% longer setting time, lower hydration heat, more delayed hydration heat evolution and lower amount of hydration products at early ages. Furthermore, the adsorption behavior of SPCE and CPCE in cement pastes and the zeta potential were investigated, and then the working mechanism of SPCE was theoretically explained. It is interesting that changing topological structure from comb-shape to star-shape can achieve the optimization of dispersion effect, and further improve the working effectiveness. The aims of this study are to provide a new avenue to synthesize superplasticizer with novel structure achieving the chemical diversity of superplasticizer structure, and to verify the contribution of optimizing molecular shape. This new type of superplasticizer can be used as a rheology modifying agent in fresh cement-based materials. Copyright © 2017 Elsevier Inc. All rights reserved.

Perfect fluidity of a dissipative system: Analytical solution for the Boltzmann equation in AdS 2 Ⓧ S 2

DOE PAGES

Noronha, Jorge; Denicol, Gabriel S.

2015-12-30

In this paper we obtain an analytical solution of the relativistic Boltzmann equation under the relaxation time approximation that describes the out-of-equilibrium dynamics of a radially expanding massless gas. This solution is found by mapping this expanding system in flat spacetime to a static flow in the curved spacetime AdS 2 Ⓧ S 2. We further derive explicit analytic expressions for the momentum dependence of the single-particle distribution function as well as for the spatial dependence of its moments. We find that this dissipative system has the ability to flow as a perfect fluid even though its entropy density doesmore » not match the equilibrium form. The nonequilibrium contribution to the entropy density is shown to be due to higher-order scalar moments (which possess no hydrodynamical interpretation) of the Boltzmann equation that can remain out of equilibrium but do not couple to the energy-momentum tensor of the system. Furthermore, in this system the slowly moving hydrodynamic degrees of freedom can exhibit true perfect fluidity while being totally decoupled from the fast moving, nonhydrodynamical microscopic degrees of freedom that lead to entropy production.« less

Effect of a Vietnamese Cinnamomum cassia essential oil and its major component trans-cinnamaldehyde on the cell viability, membrane integrity, membrane fluidity, and proton motive force of Listeria innocua.

PubMed

Trinh, Nga-Thi-Thanh; Dumas, Emilie; Thanh, Mai Le; Degraeve, Pascal; Ben Amara, Chedia; Gharsallaoui, Adem; Oulahal, Nadia

2015-04-01

The antibacterial mechanism of a Cinnamomum cassia essential oil from Vietnam and of its main component (trans-cinnamaldehyde, 90% (m/m) of C. cassia essential oil) against a Listeria innocua strain was investigated to estimate their potential for food preservation. In the presence of C. cassia essential oil or trans-cinnamaldehyde at their minimal bactericidal concentration (2700 μg·mL(-1)), L. innocua cells fluoresced green after staining with Syto9® and propidium iodide, as observed by epifluorescence microscopy, suggesting that the perturbation of membrane did not cause large pore formation and cell lysis but may have introduced the presence of viable but nonculturable bacteria. Moreover, the fluidity, potential, and intracellular pH of the cytoplasmic membrane were perturbed in the presence of the essential oil or trans-cinnamaldehyde. However, these membrane perturbations were less severe in the presence of trans-cinnamaldehyde than in the presence of multicomponent C. cassia essential oil. This indicates that in addition to trans-cinnamaldehyde, other minor C. cassia essential oil components play a major role in its antibacterial activity against L. innocua cells.

Temperature-induced changes in lecithin model membranes detected by novel covalent spin-labelled phospholipids.

PubMed

Stuhne-Sekalec, L; Stanacev, N Z

1977-02-01

Several spin-labelled phospholipids carrying covalently bound 5-doxylstearic acid (2-(3-carboxydecyl)-2-hexyl-4,4-dimethyl-3-oxazolidinoxyl) were intercalated in liposomes of saturated and unsaturated lecithins. Temperature-induced changes of these liposomes, detected by the spin-labelled phospholipids, were found to be in agreement with the previously described transitions of hydrocarbon chains of host lecithins detected by different probes and different techniques, establishing that spin-labelled phosopholipids are sensitive probes for the detection of temperature-induced changes in lecithin model membranes. In addition to the detection of already-known transitions in lecithin liposomes, the coexistence of two distinctly different enviroments was observed above the characteristic transition temperature. This phenomenon was tentatively attributed to the influence of the lecithin polar group on the fluidity of fatty acyl chains near the polar group. Combined with other results from the literature, the coexistence of two environments could be associated with the coexistence of two conformational isomers of lecithin, differing in the orientation of the polar head group with respect to the plane of bilayer. These findings have been discussed in view of the present state of knowledge regarding temperature-induced changes in model membranes.

Two-Point Microrheology of Phase-Separated Domains in Lipid Bilayers

PubMed Central

Hormel, Tristan T.; Reyer, Matthew A.; Parthasarathy, Raghuveer

2015-01-01

Though the importance of membrane fluidity for cellular function has been well established for decades, methods for measuring lipid bilayer viscosity remain challenging to devise and implement. Recently, approaches based on characterizing the Brownian dynamics of individual tracers such as colloidal particles or lipid domains have provided insights into bilayer viscosity. For fluids in general, however, methods based on single-particle trajectories provide a limited view of hydrodynamic response. The technique of two-point microrheology, in which correlations between the Brownian dynamics of pairs of tracers report on the properties of the intervening medium, characterizes viscosity at length-scales that are larger than that of individual tracers and has less sensitivity to tracer-induced distortions, but has never been applied to lipid membranes. We present, to our knowledge, the first two-point microrheological study of lipid bilayers, examining the correlated motion of domains in phase-separated lipid vesicles and comparing one- and two-point results. We measure two-point correlation functions in excellent agreement with the forms predicted by two-dimensional hydrodynamic models, analysis of which reveals a viscosity intermediate between those of the two lipid phases, indicative of global fluid properties rather than the viscosity of the local neighborhood of the tracer. PMID:26287625

Structured Water Layers Adjacent to Biological Membranes

PubMed Central

Higgins, Michael J.; Polcik, Martin; Fukuma, Takeshi; Sader, John E.; Nakayama, Yoshikazu; Jarvis, Suzanne P.

2006-01-01

Water amid the restricted space of crowded biological macromolecules and at membrane interfaces is essential for cell function, though the structure and function of this “biological water” itself remains poorly defined. The force required to remove strongly bound water is referred to as the hydration force and due to its widespread importance, it has been studied in numerous systems. Here, by using a highly sensitive dynamic atomic force microscope technique in conjunction with a carbon nanotube probe, we reveal a hydration force with an oscillatory profile that reflects the removal of up to five structured water layers from between the probe and biological membrane surface. Further, we find that the hydration force can be modified by changing the membrane fluidity. For 1,2-dipalmitoyl-sn-glycero-3-phosphocholine gel (Lβ) phase bilayers, each oscillation in the force profile indicates the force required to displace a single layer of water molecules from between the probe and bilayer. In contrast, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine fluid (Lα) phase bilayers at 60°C and 1,2-dioleoyl-sn-glycero-3-phosphocholine fluid (Lα) phase bilayers at 24°C seriously disrupt the molecular ordering of the water and result predominantly in a monotonic force profile. PMID:16798815

Effects of cholesterol on plasma membrane lipid order in MCF-7 cells by two-photon microscopy

NASA Astrophysics Data System (ADS)

Zeng, Yixiu; Chen, Jianling; Yang, Hongqin; Wang, Yuhua; Li, Hui; Xie, Shusen

2014-09-01

Lipid rafts are cholesterol- and glycosphingolipids- enriched microdomains on plasma membrane surface of mammal cells, involved in a variety of cellular processes. Depleting cholesterol from the plasma membrane by drugs influences the trafficking of lipid raft markers. Optical imaging techniques are powerful tools to study lipid rafts in live cells due to its noninvasive feature. In this study, breast cancer cells MCF-7 were treated with different concentrations of MβCD to deplete cholesterol and an environmentally sensitive fluorescence probe, Laurdan was loaded to image lipid order by two-photon microscopy. The generalized polarization (GP) values were calculated to distinguish the lipid order and disorder phase. GP images and GP distributions of native and cholesterol-depleted MCF-7 cells were obtained. Our results suggest that even at low concentration (0.5 mM) of MβCD, the morphology of the MCF-7 cells changes. Small high GP areas (lipid order phase) decrease more rapidly than low GP areas (lipid disorder phase), indicating that lipid raft structure was altered more severely than nonraft domains. The data demonstrates that cholesterol dramatically affect raft coverage and plasma membrane fluidity in living cells.

Family Drawings before and after Treatment for Child Conduct Problems: Fluidity of Family Dysfunction.

PubMed

Kloft, Lilian; Hawes, David; Moul, Caroline; Sultan, Sonia; Dadds, Mark

2017-01-01

Children's drawings have previously been found to reflect their representations of family relationships. The present study examined whether evidence-based parent training for child conduct problems impacts on representations of family functioning using the Family Drawing Paradigm (FDP). N  = 53 clinic-referred children (aged 3-15) with conduct problems and their families were assessed pre-treatment and at 6-month follow-up on a modified version of the FDP. Analyses of changes in the FDP revealed improvements in family functioning but not tone of language (as indicated by written descriptors) following treatment. Higher family dysfunction scores were associated with increased levels of callous-unemotional (CU) traits in the children pre-treatment. Children with high levels of CU, however, demonstrated greater change in FDP dysfunction than a low CU group, resulting in similar levels at follow-up. CU traits also moderated the association between change in family warmth and conduct problem severity, with increased FDP warmth more strongly related to improved conduct problems in the high vs. the low CU group. FDP drawings are sensitive to changes in family functioning arising from parent training, accounting for unique variance in child outcomes independent of verbal reports.

Bioeffects of low-energy continuous ultrasound on isolated sarcoma 180 cells.

PubMed

Wang, Xiaobing; Liu, Quanhong; Wang, Zhezhi; Wang, Pan; Hao, Qiao; Li, Chendi

2009-01-01

The aim of this study was to investigate the mechanism underlying bioeffects of low-intensity continuous ultrasound on isolated sarcoma 180 (S180) cells and cellular responses to these effects. After sonication, several structural and functional parameters were examined to elucidate ultrasound-induced cell damage. Instant disruption of the cell membrane might be caused by acoustic cavitation, producing mechanical and chemical effects that acted simultaneously on S180 cells; this could be reflected by immediate (morphological) changes such as membrane permeability, membrane fluidity, lipid peroxidation and the generation of hydroxyl radicals in culture medium. Our results of the delayed effects also indicated S180 cells were sensitive to ultrasound-induced apoptosis, and the rate of apoptosis rose gradually with a prolonged incubation time. The presence of apoptotic cells was identified by a distinct morphological form characterized by membrane blebbing, cell shrinkage, chromatin condensation and DNA fragmentation. Moreover, delayed cytotoxicity was accompanied by an increase in intracellular reactive oxygen species (ROS) and a decrease in the mitochondrial membrane potential, and the two events presented obviously a negative correlation. ROS secondarily generated from damaged mitochondria may play a role in the induction of apoptosis. Copyright 2009 S. Karger AG, Basel.

(1)H NMR-Based Metabolomics and Neurotoxicity Study of Cerebrum and Cerebellum in Rats Treated with Cinnabar, a Traditional Chinese Medicine.

PubMed

Wei, Lai; Xue, Rong; Zhang, Panpan; Wu, Yijie; Li, Xiaojing; Pei, Fengkui

2015-08-01

Cinnabar, an important traditional Chinese mineral medicine, has been widely used as a Chinese patent medicine ingredient for sedative therapy. Nevertheless, the neurotoxic effects of cinnabar have also been noted. In this study, (1)H NMR-based metabolomics, combined with multivariate pattern recognition, were applied to investigate the neurotoxic effects of cinnabar after intragastrical administration (dosed at 2 and 5 g/kg body weight) on male Wistar rats. The metabolite variations induced by cinnabar were characterized by increased levels of glutamate, glutamine, myo-inositol, and choline, as well as decreased levels of GABA, taurine, NAA, and NAAG in tissue extracts of the cerebellum and cerebrum. These findings suggested that cinnabar induced glutamate excitotoxicity, neuronal cell loss, osmotic state changes, membrane fluidity disruption, and oxidative injury in the brain. We also show here that there is a dose- and time-dependent neurotoxicity of cinnabar, and that cerebellum was more sensitive to cinnabar induction than cerebrum. This work illustrates the utility and reliability of (1)H NMR-based metabolomics approach for examining the potential neurotoxic effects of cinnabar and other traditional Chinese medicines.

[Liquid modernity and internet addiction].

PubMed

Doi, Takayoshi

2015-09-01

We are afraid that we are not always connected to somebody. There are such strong feelings to human relations in the background of internet addiction. It is reflection of today's social fluidity, and it is also reflection of the strength of the approval desire to occur from there. The feeling of fear in being off human relations in this society directs us to always-on connection by the internet.

Bloom's "Normal" (2002) and Tarttelin's "Golden Boy" (2013): Teaching Gender Fluidity Written across Time and Text

ERIC Educational Resources Information Center

LeSavoy, Barbara

2016-01-01

The author is in a faculty position in women and gender studies (WGST) at a comprehensive public university in western New York. In this article, the author summarize theories of identity and voice as backdrop for inquiry, transitioning to a systematic discussion of teaching about sex and gender identity to differently positioned learners, drawing…

Cryopreservation of canine semen - new challenges.

PubMed

Farstad, W

2009-07-01

Egg yolk (EY) protects cell membranes against cold shock, and it prevents or restores the loss of phospholipids from the membrane. EY has been widely used in semen extenders. It has been added to Tris-Glucose buffer and has been widely used for cooling and cryopreservation of canine semen. EY is not a defined entity, but a complex biological compound containing proteins, vitamins, phospholipids, glucose and antioxidants which are all potentially useful for cell membrane integrity. Unfortunately, it also is a biologically hazardous compound. Hence, whole EY needs to be replaced by other chemically defined components for semen processing in dogs. Freezing poor semen does not improve its quality, so attention must be focused on how to cope with dogs whose semen does not freeze well, and on designing individual freezing extenders for semen from such males. Furthermore, differences have been found among canid species in the ability of their spermatozoa to withstand freezing. There are differences in sperm membrane fatty acid composition among species, which may explain part of these differences. If the presence of long-chained polyunsaturated fatty acids contributes to increased membrane fluidity, this relationship may be biphasic, i.e. either too much membrane fluidity, or too little, could compromise successful sperm cryopreservation. An increase in fluidity of the outer leaflet of the plasma membrane has been shown in frozen thawed dog spermatozoa. The protective effect of exogenous lipids may lie in close association with the membrane rather than in modification or rearrangement of the membrane. This also points at lipids as an important, if not entirely new group of substances, which may substitute standard EY-based diluents in preserving sperm survival during freezing. EY-derived phospholipids or lecithin could be used to replace whole EY. Vegetable lecithin is currently investigated to avoid using substances of animal origin. EY also contains antioxidants which prevent cells from oxidative damage due to the generation of reactive oxygen species. An increasing number of publications now recognize the significance of protecting sperm from this damage during processing by using dietary or diluent supplemented antioxidants. This paper aims at looking at some of the new challenges in freezing of dog semen.

pH-induced change in cell susceptibility to butanol in a high butanol-tolerant bacterium, Enterococcus faecalis strain CM4A.

PubMed

Kanno, Manabu; Tamaki, Hideyuki; Mitani, Yasuo; Kimura, Nobutada; Hanada, Satoshi; Kamagata, Yoichi

2015-01-01

Though butanol is considered as a potential biofuel, its toxicity toward microorganisms is the main bottleneck for the biological butanol production. Recently, butanol-tolerant bacteria have been proposed as alternative butanol production hosts overcoming the end product inhibition. One remaining key issue to be addressed is how physicochemical properties such as pH and temperature affect microbial butanol tolerance during cultivation and fermentation. We investigated the pH effect on butanol tolerance of a high butanol-tolerant bacterium, Enterococcus faecalis strain CM4A. The strain grew over a broad pH range (pH 4.0 to 12.0) and preferred alkaline pH (pH 8.0 and 10.0) in the absence of butanol. However, in the presence of butanol, strain CM4A grew better under acidic and neutral pH conditions (pH 6.0 and 6.8). Membrane fatty acid analysis revealed that the cells exposed to butanol exhibited increased cyclopropane and saturated fatty acids, which contribute to butanol tolerance of the strain by decreasing membrane fluidity, more evidently at acidic and neutral pH than at alkaline pH. Meanwhile, the strain grown under alkaline pH without butanol increased short chain fatty acids, which is involved in increasing membrane fluidity for alkaline adaptation. Such a change was not observed in the cells grown under alkaline pH with butanol. These results suggested that strain CM4A simultaneously exposed to butanol and alkali stresses was not likely able to properly adjust membrane fluidity due to the opposite response to each stress and thereby showed low butanol tolerance under alkaline pH. Indeed, the cells exposed to butanol at alkaline pH showed an irregular shape with disrupted membrane structure under transmission electron microscopy observation, which also indicated the impact of butanol and alkali stresses on functioning of cellular membrane. The study clearly demonstrated the alkaline pH-induced increase of cell susceptibility to butanol in the tested strain. Our findings indicate the non-negligible impact of pH on microbial butanol tolerance, providing a new insight into efficient butanol production.

Biophysical characterization of the Lactobacillus delbrueckii subsp. bulgaricus membrane during cold and osmotic stress and its relevance for cryopreservation.

PubMed

Meneghel, Julie; Passot, Stéphanie; Dupont, Sébastien; Fonseca, Fernanda

2017-02-01

Freezing lactic acid bacteria often leads to cell death and loss of technological properties. Our objective was to provide an in-depth characterization of the biophysical properties of the Lactobacillus delbrueckii subsp. bulgaricus membrane in relation to its freeze resistance. Freezing was represented as a combination of cold and osmotic stress. This work investigated the relative incidence of increasing sucrose concentrations coupled or not with subzero temperatures without ice nucleation on the biological and biophysical responses of two strains with different membrane fatty acid compositions and freeze resistances. Following exposure of bacterial cells to the highest sucrose concentration, the sensitive strain exhibited a survival rate of less than 10 % and 5 h of acidifying activity loss. Similar biological activity losses were observed upon freeze-thawing and after osmotic treatment for each strain thus highlighting osmotic stress as the main source of cryoinjury. The direct measurement of membrane fluidity by fluorescence anisotropy was linked to membrane lipid organization characterized by FTIR spectroscopy. Both approaches made it possible to investigate the specific contributions of the membrane core and the bilayer external surface to cell degradation caused by cold and osmotic stress. Cold-induced membrane rigidification had no significant implication on bacterial freeze-thaw resistance. Interactions between extracellular sucrose and membrane phospholipid headgroups under osmotic stress were also observed. Such interactions were more evident in the sensitive strain and when increasing sucrose concentration, thus suggesting membrane permeabilization. The relevance of biophysical properties for elucidating mechanisms of cryoinjury and cryoprotection is discussed.

Army Reserve Components Research Roadmap Volume 2: Research Agenda

DTIC Science & Technology

1997-09-01

over a 150-mile radius. This obviously makes training above the company level difficult for any time other than annual training (AT). In addition...at a higher level of decision- making , fluidity in the assignments of force structures to units creates wide spread change which affects whole units...can increasingly make TADSS and other enhancements practical solutions to persistent training needs. It should also be noted that the questions

Consequences of transition from liquid chromatography to supercritical fluid chromatography on the overall performance of a chiral zwitterionic ion-exchanger.

PubMed

Wolrab, Denise; Frühauf, Peter; Gerner, Christopher; Kohout, Michal; Lindner, Wolfgang

2017-09-29

Major differences in the chromatographic performance of a zwitterion ion-exchange type (ZWIX) chiral stationary phase (CSP) in supercritical fluid chromatography (SFC) and high-performance liquid chromatography (HPLC) have been observed. To explain these differences, transition from HPLC to SFC conditions has been performed. The amount of a protic organic modifier in supercritical carbon dioxide (scCO 2 ) was stepwise increased and the effect of this change studied using acidic, basic and ampholytic analytes. At the same time, the effect of various basic additives to the mobile phase and transient acidic buffer species, formed by the reaction of scCO 2 with the organic modifier and additives, was assessed. Evidence is provided that a transient acid together with the intrinsic counter-ions present in the ZWIX selector structure drive the elution of analytes even when no buffer is employed. We show that the tested analytes can be enantioseparated under both SFC and HPLC conditions; the best conditions for the resolution of ampholytes are in the so-called enhanced-fluidity mobile phase region. As a consequence, subcritical fluid and enhanced-fluidity mobile phase regions seem to be chromatographic modes with a high potential for operating ZWIX CSPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Sputtered Gum metal thin films showing bacterial inactivation and biocompatibility.

PubMed

Achache, S; Alhussein, A; Lamri, S; François, M; Sanchette, F; Pulgarin, C; Kiwi, J; Rtimi, S

2016-10-01

Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) and Ti-24Nb-(N) (TN-N) (at.%) were deposited by direct current magnetron sputtering (DCMS) in different reactive atmospheres. The effects of oxygen doping (TNTZ-O) and/or nitrogen doping (TN-N) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that, in both cases, 1sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young's modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. Bacterial inactivation was concomitant with the observed pH and surface potential changes under light and in the dark. The increased cell fluidity leading to bacterial lysis was followed during the bacterial inactivation time. The increasing cell wall fluidity was attributed to the damage of the bacterial outer cell which losing its capacity to regulate the ions exchange in and out of the bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanical coupling of microtubule-dependent motor teams during peroxisome transport in Drosophila S2 cells.

PubMed

De Rossi, María Cecilia; Wetzler, Diana E; Benseñor, Lorena; De Rossi, María Emilia; Sued, Mariela; Rodríguez, Daniela; Gelfand, Vladimir; Bruno, Luciana; Levi, Valeria

2017-12-01

Intracellular transport requires molecular motors that step along cytoskeletal filaments actively dragging cargoes through the crowded cytoplasm. Here, we explore the interplay of the opposed polarity motors kinesin-1 and cytoplasmic dynein during peroxisome transport along microtubules in Drosophila S2 cells. We used single particle tracking with nanometer accuracy and millisecond time resolution to extract quantitative information on the bidirectional motion of organelles. The transport performance was studied in cells expressing a slow chimeric plus-end directed motor or the kinesin heavy chain. We also analyzed the influence of peroxisomes membrane fluidity in methyl-β-ciclodextrin treated cells. The experimental data was also confronted with numerical simulations of two well-established tug of war scenarios. The velocity distributions of retrograde and anterograde peroxisomes showed a multimodal pattern suggesting that multiple motor teams drive transport in either direction. The chimeric motors interfered with the performance of anterograde transport and also reduced the speed of the slowest retrograde team. In addition, increasing the fluidity of peroxisomes membrane decreased the speed of the slowest anterograde and retrograde teams. Our results support the existence of a crosstalk between opposed-polarity motor teams. Moreover, the slowest teams seem to mechanically communicate with each other through the membrane to trigger transport. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells.

PubMed

Jessel, Robert; Haertel, Steffen; Socaciu, Carmen; Tykhonova, Svetlana; Diehl, Horst A

2002-01-01

We investigated the time-dependence of apoptotic events in EL4 cells by monitoring plasma membrane changes in correlation to DNA fragmentation and cell shrinkage. We applied three apoptosis inducers (staurosporine, tubericidine and X-rays) and we looked at various markers to follow the early-to-late apoptotic events: phospholipid translocation (identified through annexin V-fluorescein assay and propidium iodide), lipid package (via merocyanine assay), membrane fluidity and anisotropy (via fluorescent measurements), DNA fragmentation by the fluorescence-labeling test and cell size measurements. The different apoptotic inducers caused different reactions of the cells: staurosporine induced apoptosis most rapidly in a high number of cells, tubercidine triggered apoptosis only in the S phase cells, while X-rays caused a G2/M arrest and subsequently apoptosis. Loss of lipid asymmetry is promptly detectable after one hour of incubation time. The phosphatidylserine translocation, decrease of lipid package and anisotropy, and the increase of membrane fluidity appeared to be based on the same process of lipid asymmetry loss. Therefore, the DNA fragmentation and the cell shrinkage appear to be parallel and independent processes running on different time scales but which are kinetically inter-related. The results indicate different signal steps to apoptosis dependent on inducer characteristics but the kinetics of "early-to-late" apoptosis appears to be a fixed program.

Membrane lipid physiology and toxin catabolism underlie ethanol and acetic acid tolerance in Drosophila melanogaster.

PubMed

Montooth, Kristi L; Siebenthall, Kyle T; Clark, Andrew G

2006-10-01

Drosophila melanogaster has evolved the ability to tolerate and utilize high levels of ethanol and acetic acid encountered in its rotting-fruit niche. Investigation of this phenomenon has focused on ethanol catabolism, particularly by the enzyme alcohol dehydrogenase. Here we report that survival under ethanol and acetic acid stress in D. melanogaster from high- and low-latitude populations is an integrated consequence of toxin catabolism and alteration of physical properties of cellular membranes by ethanol. Metabolic detoxification contributed to differences in ethanol tolerance between populations and acclimation temperatures via changes in both alcohol dehydrogenase and acetyl-CoA synthetase mRNA expression and enzyme activity. Independent of changes in ethanol catabolism, rapid thermal shifts that change membrane fluidity had dramatic effects on ethanol tolerance. Cold temperature treatments upregulated phospholipid metabolism genes and enhanced acetic acid tolerance, consistent with the predicted effects of restoring membrane fluidity. Phospholipase D was expressed at high levels in all treatments that conferred enhanced ethanol tolerance, suggesting that this lipid-mediated signaling enzyme may enhance tolerance by sequestering ethanol in membranes as phophatidylethanol. These results reveal new candidate genes underlying toxin tolerance and membrane adaptation to temperature in Drosophila and provide insight into how interactions between these phenotypes may underlie the maintenance of latitudinal clines in ethanol tolerance.

Plasticizing aqueous suspensions of concentrated alumina with maltodextrin sugar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schilling, C.H.; Bellman, R.A.; Smith, R.M.

1999-01-01

Aqueous suspensions of submicrometer, 20 vol% Al{sub 2}O{sub 3} powder exhibited a transition from strongly flocculated, thixotropic behavior to a low-viscosity, Newtonian-like state upon adding small amounts of maltodextrin (0.03 g of maltodextrin/(g of Al{sub 2}O{sub 3})). These suspensions could be filter pressed to highly dense (57%) and extrudable pastes only when prepared with maltodextrin. The authors analyzed the interaction of maltodextrin with Al{sub 2}O{sub 3} powder surfaces and quantitatively measured the resulting claylike consolidation, rheological, and extrusion behaviors. Benbow extrusion parameters were comparable to, but higher than, those of kaolin at approximately the same packing density of 57 vol%.more » In contrast, Al{sub 2}O{sub 3} filter cakes without maltodextrin at 57 vol% density were too stiff to be extruded. Measurements of rheological properties, acoustophoresis, electrophoresis, sorption isotherms, and diffuse reflectance Fourier infrared spectroscopy supported the hypothesis that sorbate-mediated steric hindrance, rather than electrostatic, interparticle repulsion, is important to enhancing the consolidation and fluidity of maltodextrin-Al{sub 2}O{sub 3} suspensions. Viscosity measurements on aqueous maltodextrin solutions indicated that free maltodextrin in solution does not improve suspension fluidity by decreasing the viscosity of the interparticle solution.« less

Multi-Scale Low-Entropy Method for Optimizing the Processing Parameters during Automated Fiber Placement

PubMed Central

Han, Zhenyu; Sun, Shouzheng; Fu, Hongya; Fu, Yunzhong

2017-01-01

Automated fiber placement (AFP) process includes a variety of energy forms and multi-scale effects. This contribution proposes a novel multi-scale low-entropy method aiming at optimizing processing parameters in an AFP process, where multi-scale effect, energy consumption, energy utilization efficiency and mechanical properties of micro-system could be taken into account synthetically. Taking a carbon fiber/epoxy prepreg as an example, mechanical properties of macro–meso–scale are obtained by Finite Element Method (FEM). A multi-scale energy transfer model is then established to input the macroscopic results into the microscopic system as its boundary condition, which can communicate with different scales. Furthermore, microscopic characteristics, mainly micro-scale adsorption energy, diffusion coefficient entropy–enthalpy values, are calculated under different processing parameters based on molecular dynamics method. Low-entropy region is then obtained in terms of the interrelation among entropy–enthalpy values, microscopic mechanical properties (interface adsorbability and matrix fluidity) and processing parameters to guarantee better fluidity, stronger adsorption, lower energy consumption and higher energy quality collaboratively. Finally, nine groups of experiments are carried out to verify the validity of the simulation results. The results show that the low-entropy optimization method can reduce void content effectively, and further improve the mechanical properties of laminates. PMID:28869520

Multi-Scale Low-Entropy Method for Optimizing the Processing Parameters during Automated Fiber Placement.

PubMed

Han, Zhenyu; Sun, Shouzheng; Fu, Hongya; Fu, Yunzhong

2017-09-03

Automated fiber placement (AFP) process includes a variety of energy forms and multi-scale effects. This contribution proposes a novel multi-scale low-entropy method aiming at optimizing processing parameters in an AFP process, where multi-scale effect, energy consumption, energy utilization efficiency and mechanical properties of micro-system could be taken into account synthetically. Taking a carbon fiber/epoxy prepreg as an example, mechanical properties of macro-meso-scale are obtained by Finite Element Method (FEM). A multi-scale energy transfer model is then established to input the macroscopic results into the microscopic system as its boundary condition, which can communicate with different scales. Furthermore, microscopic characteristics, mainly micro-scale adsorption energy, diffusion coefficient entropy-enthalpy values, are calculated under different processing parameters based on molecular dynamics method. Low-entropy region is then obtained in terms of the interrelation among entropy-enthalpy values, microscopic mechanical properties (interface adsorbability and matrix fluidity) and processing parameters to guarantee better fluidity, stronger adsorption, lower energy consumption and higher energy quality collaboratively. Finally, nine groups of experiments are carried out to verify the validity of the simulation results. The results show that the low-entropy optimization method can reduce void content effectively, and further improve the mechanical properties of laminates.

Quality design of belite–melilite clinker

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurokawa, Daisuke, E-mail: daisuke_kurokawa@taiheiyo-cement.co.jp; Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555; Honma, Kenichi

2013-12-15

We have developed a new cement clinker, consisting mainly of belite and melilite, which is capable of increasing the amount of recycled waste as a part of its raw materials. We analyzed clinkers with a wide range of compositions, and clarified the quantitative relationship between the chemical and mineral compositions. Clinkers consisting mostly of belite and melilite were successfully obtained at the CaO/SiO{sub 2} mass ratio of 1.7 to 1.9. Test cements were prepared using these clinkers and mixed with OPC for the evaluation of fluidity and strength. The belite–melilite cement was found to have good fluidity, and the belite–melilitemore » cement mixed with OPC at up to 30% exhibited a satisfactory long term strength equivalent to the OPC, demonstrating the potential as an alternative to OPC. Electron probe microanalysis revealed the relatively high concentration of diphosphorus pentaoxide in belite, suggesting this component might contribute to the strength enhancement of the cement. -- Highlights: •A new cement clinker consisting mainly of belite and melilite was designed. •The clinker enables the use of various recycled wastes as part of its raw materials. •The relationship between the chemical and mineral compositions was clarified. •This cement mixed with OPC at up to 30% exhibited a good quality equivalent to OPC.« less

Static Holdup of Liquid Slag in Simulated Packed Coke Bed Under Oxygen Blast Furnace Ironmaking Conditions

NASA Astrophysics Data System (ADS)

Wang, Guang; Liu, Yingli; Zhou, Zhenfeng; Wang, Jingsong; Xue, Qingguo

2018-01-01

The liquid-phase flow behavior of slag in the lower zone of a blast furnace affects the furnace permeability, performance, and productivity. The effects of pulverized coal injection (PCI) on the behavior of simulated primary slag flow were investigated by quantifying the effect of key variables including Al/Si ratio [Al2O3 (wt.%) to SiO2 (wt.%)] and the amount of unburnt pulverized coal (UPC) at 1500°C. Viscosity analysis demonstrated that the slag fluidity decreased as the Al/Si ratio was increased (from 0.35 to 0.50), resulting in gradual increase of the static holdup. Increasing the amount of UPC resulted in a significant increase of the static holdup. Flooding analysis was applied to determine the maximum static holdup, which was found to be 11.5%. It was inferred that the burnout rates of pulverized coal should exceed 78.6% and 83.9% in traditional and oxygen blast furnaces, respectively.

Myosin II Controls Junction Fluctuations to Guide Epithelial Tissue Ordering.

PubMed

Curran, Scott; Strandkvist, Charlotte; Bathmann, Jasper; de Gennes, Marc; Kabla, Alexandre; Salbreux, Guillaume; Baum, Buzz

2017-11-20

Under conditions of homeostasis, dynamic changes in the length of individual adherens junctions (AJs) provide epithelia with the fluidity required to maintain tissue integrity in the face of intrinsic and extrinsic forces. While the contribution of AJ remodeling to developmental morphogenesis has been intensively studied, less is known about AJ dynamics in other circumstances. Here, we study AJ dynamics in an epithelium that undergoes a gradual increase in packing order, without concomitant large-scale changes in tissue size or shape. We find that neighbor exchange events are driven by stochastic fluctuations in junction length, regulated in part by junctional actomyosin. In this context, the developmental increase of isotropic junctional actomyosin reduces the rate of neighbor exchange, contributing to tissue order. We propose a model in which the local variance in tension between junctions determines whether actomyosin-based forces will inhibit or drive the topological transitions that either refine or deform a tissue. Copyright © 2017. Published by Elsevier Inc.

Re-discovering the material body in midwifery through an exploration of theories of embodiment.

PubMed

Davis, Deborah L; Walker, Kim

2010-08-01

The body is of central concern to midwifery yet, as a profession, we have largely failed to grapple with the corpus of feminist and other literature that deals with the body. This article provides an overview of the ways in which the body has been theorised, from the essential and biological through to postmodern theories of the body. We draw attention to the limitations of some of these approaches, suggesting that Elizabeth Grosz's schema of the Möbius strip (representing the inter-relationships between the inside and outside, culture and nature) provides a useful framework for thinking about the body; one that avoids a biological materialism that disregards the effect of culture, and a cultural determinism that neglects the corporeal body. Recognising the multiplicity and fluidity of women's experiences of pregnancy, their body and childbearing emancipates us from the limitations imposed by the masculinist Western philosophical traditions that we have inherited. Copyright 2008 Elsevier Ltd. All rights reserved.

Effect of chitosan ethers on fresh state properties of lime mortars

NASA Astrophysics Data System (ADS)

Vyšvařil, M.; Žižlavský, T.

2017-10-01

The fresh state properties of mortars are eminently important since determine the material workability and also have a great influence on its hardened state characteristics. In this paper, the behaviour of fresh lime mortars modified by etherified derivatives of chitosan (hydroxypropylchitosan (HPCH) and carboxymethylchitosan (CMCH)) is assessed with the purpose of exploring a new application of such derivatives as lime mortar admixtures. The rheological parameters (relative yield stress, consistency coefficient and fluidity index) and viscoelastic properties were correlated with flow table tests, relative density measurements, water retention abilities of mortars and air content in mortars. Results were seen to be strongly dependent on substituents of the chitosan. Non-ionic derivative (HPCH) had a plasticizing influence on the mortars; the ionic CMCH showed the thickening effect. The effect of chitosan ethers was found to be dosage-dependent. CMCH had low impact on water retention, while HPCH displayed high water retention capability. It was concluded, that the ionic derivative (CMCH) is very similar by its viscosity enhancing effect to starch ether.

Aluminum and temperature alteration of cell membrane permeability of Quercus rubra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Junping Chen; Sucoff, E.I.; Stadelmann, E.J.

1991-06-01

Al toxicity is the major factor limiting plant growth in acid soils. This report extends research on Al-induced changes in membrane behavior of intact root cortex cells of Northern red oak (Quercus rubra). Membrane permeability was determined by the plasmometric method for individual intact cells at temperatures from 2 or 4 to 35 C. Al (0.37 millimolar) significantly increased membrane permeability to urea and monoethyl urea and decreased permeability to water. Al significantly altered the activation energy required to transport water (+ 32%), urea (+ 9%), and monoethyl urea ({minus}7%) across cell membranes. Above 9 C, Al increased the lipidmore » partiality of the cell membranes; below 7 C, Al decreased it. Al narrowed by 6 C the temperature range over which plasmolysis occurred without membrane damage. These changes in membrane behavior are explainable if Al reduced membrane lipid fluidity and kink frequency and increases packing density and the occurrence of straight lipid chains.« less

Coking properties of coal under pressure and their influence on moving-bed gasification. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lancet, M.S.; Curran, G.P.; Sim, F.A.

1982-08-01

The coking properties of seven bituminous coals, including three Eastern US coals, one Midwestern US coal, a Western US coal and two from the UK were studied with respect to the possible utilization of these coals in moving bed gasifier systems. Complete physical, chemical and petrographic analyses were obtained for each coal in addition to the highly specialized CCDC simulated gasifier coking test data. The effects of total pressure, hydrogen partial pressure, heating rate and the addition of gob and tar on the fluidity and swelling properties of each coal was studied. Samples of each coal were shock heated undermore » pressure to simulate coking in the top of a Lurgi gasifier. The resultant cokes were tested for various physical properties and the product yields were determined. Gas release patterns during pressurized pyrolysis were obtained in several instances. The data obtained in this work should provide a valuable data base for future gasifier feedstock evaluation programs.« less

Aspirin Increases the Solubility of Cholesterol in Lipid Membranes

NASA Astrophysics Data System (ADS)

Alsop, Richard; Barrett, Matthew; Zheng, Sonbo; Dies, Hannah; Rheinstadter, Maikel

2014-03-01

Aspirin (ASA) is often prescribed for patients with high levels of cholesterol for the secondary prevention of myocardial events, a regimen known as the Low-Dose Aspirin Therapy. We have recently shown that Aspirin partitions in lipid bilayers. However, a direct interplay between ASA and cholesterol has not been investigated. Cholesterol is known to insert itself into the membrane in a dispersed state at moderate concentrations (under ~37.5%) and decrease fluidity of membranes. We prepared model lipid membranes containing varying amounts of both ASA and cholesterol molecules. The structure of the bilayers as a function of ASA and cholesterol concentration was determined using high-resolution X-ray diffraction. At cholesterol levels of more than 40mol%, immiscible cholesterol plaques formed. Adding ASA to the membranes was found to dissolve the cholesterol plaques, leading to a fluid lipid bilayer structure. We present first direct evidence for an interaction between ASA and cholesterol on the level of the cell membrane.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Towata, Tomomi; Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811; Komizu, Yuji

Primary effusion lymphoma (PEL) is an aggressive neoplasm caused by human herpes virus-8 infection, and is generally resistant to chemotherapy. Hybrid liposomes, composed of dimyristoylphosphatidylcholine (DMPC) and polyoxyethylene (21) dodecyl ether (C{sub 12}(EO){sub 21}) (HL-21), were rapidly accumulated in the membrane of PEL cells. HL-21 also increased membrane fluidity of PEL cells, and induced caspase-3 activation along with cell death. These results suggest that HL-21 should be an effective and attractive regent for PEL treatment.

Dynamic Photonic Materials Based on Liquid Crystals (Postprint)

DTIC Science & Technology

2013-09-01

AFRL-RX-WP-JA-2015-0059 DYNAMIC PHOTONIC MATERIALS BASED ON LIQUID CRYSTALS (POSTPRINT) Luciano De Sio and Cesare Umeton University...ON LIQUID CRYSTALS (POSTPRINT) 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) (see back...10.1016/B978-0-444-62644-8.00001-7. 14. ABSTRACT Liquid crystals, combining optical non-linearity and self-organizing properties with fluidity, and being

Color and shape changing polymeric ribbons and sheets

DOEpatents

Stevens, Raymond C.; Cheng, Quan; Song, Jie

2006-05-23

The present invention herein provides the design, synthesis and characterization of compositions comprising asymmetric bolaamphiphilic lipids that form extended polymeric ribbons and wide sheets. These compositions may be doped, or interspersed, with various compounds to fine-tune the fluidity and rigidity of the bolaamphiphilic lipid composition, and promote other morphologies of the composition, including fluid vesicles and truncated flat sheets. Upon an increase in pH these compositions undergo a calorimetric and morphological transformation.

Interaction of nanoparticles with lipid membranes: a multiscale perspective.

PubMed

Montis, Costanza; Maiolo, Daniele; Alessandri, Ivano; Bergese, Paolo; Berti, Debora

2014-06-21

Freestanding lipid bilayers were challenged with 15 nm Au nanospheres either coated by a citrate layer or passivated by a protein corona. The effect of Au nanospheres on the bilayer morphology, permeability and fluidity presents strong differences or similarities, depending on the observation length scale, from the colloidal to the molecular domains. These findings suggest that the interaction between nanoparticles and lipid membranes should be conveniently treated as a multiscale phenomenon.

Lens lipids.

PubMed

Zelenka, P S

1984-11-01

Lens cells can synthesize, degrade, and remodel lipids. Endogenous lipid synthesis, in conjunction with uptake of exogenous cholesterol and certain fatty acids, leads to the formation of a plasma membrane that is especially rich in sphingomyelin, cholesterol, and long-chain saturated fatty acids. As a result of this unusual lipid composition, lens membranes have very low fluidity, which is restricted even further by lipid-protein interactions. The composition and metabolism of membrane lipids may affect the formation of various types of cataracts. Diets rich in vegetable oils offer some protection against the formation of osmotic cataracts and the hereditary cataract of the RCS rat, although the mechanism of this effect is not clear. Vitamin E also protects against the formation of several types of cataract in vivo and in vitro, suggesting that lipid peroxidation may play a role in cataractogenesis. Certain drugs which inhibit lipid synthesis or degradation are cataractogenic, and a deficiency in cataractogenic, and a deficiency in phosphatidylserine is associated with a loss of Na+/K+ ATPase activity in several types of cataract. Human senile cataracts show a marked loss of protein-lipid interactions, although the overall lipid composition is normal. This loss of protein-lipid interactions may be related to oxidative damage to membrane-associated proteins. Interestingly, the decrease in the fluidity of lens membranes with age would counteract the formation of aqueous pores in the membrane, which can result from the oxidative cross-linking of membrane-associated proteins. Certain pathways of lipid metabolism seem to have regulatory functions. Among these are phosphatidylinositol turnover, phosphatidylethanolamine methylation, and arachidonic acid metabolism. All of these pathways function in the lens. Phosphatidylinositol turnover is correlated with the rate of lens epithelial cell division, while phosphatidylethanolamine methylation seems to be related to the initiation of lens fiber cell formation. Both pathways are associated with the release and metabolism of arachidonic acid in other cell types. While it is not known whether phosphatidylinositol turnover or phosphatidylethanolamine methylation result in the release of arachidonic acid in the lens, recent work has shown that lens cells from a variety of species can metabolize arachidonic acid by both the cyclooxygenase and lipoxygenase pathways. The possible physiological significance of these metabolites to the lens is yet to be determined.

Dimethyl sulfoxide induces oxidative stress in the yeast Saccharomyces cerevisiae.

PubMed

Sadowska-Bartosz, Izabela; Pączka, Aleksandra; Mołoń, Mateusz; Bartosz, Grzegorz

2013-12-01

Dimethyl sulfoxide (DMSO) is used as a cryoprotectant for the preservation of cells, including yeast, and as a solvent for chemical compounds. We report that DMSO induces oxidative stress in the yeast. Saccharomyces cerevisiae wt strain EG-103 and its mutants Δsod1, Δsod2, and Δsod1 Δsod2 were used. Yeast were subjected to the action of 1-14% DMSO for 1 h at 28 °C. DMSO induced a concentration-dependent inhibition of yeast growth, the effect being more pronounced for mutants devoid of SOD (especially Δsod1 Δsod2). Cell viability was compromised. DMSO-concentration-dependent activity loss of succinate dehydrogenase, a FeS enzyme sensitive to oxidative stress, was observed. DMSO enhanced formation of reactive oxygen species, estimated with dihydroethidine in a concentration-dependent manner, the effect being again more pronounced in mutants devoid of superoxide dismutases. The content of cellular glutathione was increased with increasing DMSO concentrations, which may represent a compensatory response. Membrane fluidity, estimated by fluorescence polarization of DPH, was decreased by DMSO. These results demonstrate that DMSO, although generally considered to be antioxidant, induces oxidative stress in yeast cells. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Glutamate Dehydrogenase Affects Resistance to Cell Wall Antibiotics in Bacillus subtilis

PubMed Central

Lee, Yong Heon; Kingston, Anthony W.

2012-01-01

The glutamate dehydrogenase RocG of Bacillus subtilis is a bifunctional protein with both enzymatic and regulatory functions. Here we show that the rocG null mutant is sensitive to β-lactams, including cefuroxime (CEF), and to fosfomycin but that resistant mutants arise due to gain-of-function mutations in gudB, which encodes an otherwise inactive glutamate dehydrogenase. In the presence of CEF, ΔrocG ΔgudB mutant cells exhibit growth arrest when they reach mid-exponential phase. Using microarray-based transcriptional profiling, we found that the σW regulon was downregulated in the ΔrocG ΔgudB null mutant. A survey of σW-controlled genes for effects on CEF resistance identified both the NfeD protein YuaF and the flotillin homologue YuaG (FloT). Notably, overexpression of yuaFG in the rocG null mutant prevents the growth arrest induced by CEF. The YuaG flotillin has been shown previously to localize to defined lipid microdomains, and we show here that the yuaFGI operon contributes to a σW-dependent decrease in membrane fluidity. We conclude that glutamate dehydrogenase activity affects the expression of the σW regulon, by pathways that are yet unclear, and thereby influences resistance to CEF and other antibiotics. PMID:22178969

Glutamate dehydrogenase affects resistance to cell wall antibiotics in Bacillus subtilis.

PubMed

Lee, Yong Heon; Kingston, Anthony W; Helmann, John D

2012-03-01

The glutamate dehydrogenase RocG of Bacillus subtilis is a bifunctional protein with both enzymatic and regulatory functions. Here we show that the rocG null mutant is sensitive to β-lactams, including cefuroxime (CEF), and to fosfomycin but that resistant mutants arise due to gain-of-function mutations in gudB, which encodes an otherwise inactive glutamate dehydrogenase. In the presence of CEF, ΔrocG ΔgudB mutant cells exhibit growth arrest when they reach mid-exponential phase. Using microarray-based transcriptional profiling, we found that the σ(W) regulon was downregulated in the ΔrocG ΔgudB null mutant. A survey of σ(W)-controlled genes for effects on CEF resistance identified both the NfeD protein YuaF and the flotillin homologue YuaG (FloT). Notably, overexpression of yuaFG in the rocG null mutant prevents the growth arrest induced by CEF. The YuaG flotillin has been shown previously to localize to defined lipid microdomains, and we show here that the yuaFGI operon contributes to a σ(W)-dependent decrease in membrane fluidity. We conclude that glutamate dehydrogenase activity affects the expression of the σ(W) regulon, by pathways that are yet unclear, and thereby influences resistance to CEF and other antibiotics.

Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition

PubMed Central

Qi, Yanli; Liu, Hui; Yu, Jiayin; Chen, Xiulai

2017-01-01

ABSTRACT Candida glabrata is a promising producer of organic acids. To elucidate the physiological function of the Mediator tail subunit Med15B in the response to low-pH stress, we constructed a deletion strain, C. glabrata med15BΔ, and an overexpression strain, C. glabrata HTUΔ/CgMED15B. Deletion of MED15B caused biomass production, glucose consumption rate, and cell viability to decrease by 28.3%, 31.7%, and 26.5%, respectively, compared with those of the parent (HTUΔ) strain at pH 2.0. Expression of lipid metabolism-related genes was significantly downregulated in the med15BΔ strain, whereas key genes of ergosterol biosynthesis showed abnormal upregulation. This caused the proportion of C18:1 fatty acids, the ratio of unsaturated to saturated fatty acids (UFA/SFA), and the total phospholipid content to decrease by 11.6%, 27.4%, and 37.6%, respectively. Cells failed to synthesize fecosterol and ergosterol, leading to the accumulation and a 60.3-fold increase in the concentration of zymosterol. Additionally, cells showed reductions of 69.2%, 11.6%, and 21.8% in membrane integrity, fluidity, and H+-ATPase activity, respectively. In contrast, overexpression of Med15B increased the C18:1 levels, total phospholipids, ergosterol content, and UFA/SFA by 18.6%, 143.5%, 94.5%, and 18.7%, respectively. Membrane integrity, fluidity, and H+-ATPase activity also increased by 30.2%, 6.9%, and 51.8%, respectively. Furthermore, in the absence of pH buffering, dry weight of cells and pyruvate concentrations were 29.3% and 61.2% higher, respectively, than those of the parent strain. These results indicated that in C. glabrata, Med15B regulates tolerance toward low pH via transcriptional regulation of acid stress response genes and alteration in lipid composition. IMPORTANCE This study explored the role of the Mediator tail subunit Med15B in the metabolism of Candida glabrata under acidic conditions. Overexpression of MED15B enhanced yeast tolerance to low pH and improved biomass production, cell viability, and pyruvate yield. Membrane lipid composition data indicated that Med15B might play a critical role in membrane integrity, fluidity, and H+-ATPase activity homeostasis at low pH. Thus, controlling membrane composition may serve to increase C. glabrata productivity at low pH. PMID:28710262

Social determinants of health and the Brazilian Family Health Care Program in the city of Sao Paulo, Southeastern Brazil.

PubMed

Dowbor, Tatiana Pluciennik; Westphal, Márcia Faria

2013-08-01

To analyze the current status of the interventions related to social determinants of health conducted in the context of the brazilian family health program. A case study using a mixed method approach based on a sequential explanatory strategy with 171 unit managers in the Family Health Care Program in the municipality of Sao Paulo, SP, Southeastern Brazil, in 2005/2006. Self-administered questionnaires were applied and semi-structured interviews and focus groups were conducted with a purposive sample of professionals involved in initiatives related to social determinants of health. Quantitative data were analyzed using descriptive statistics, multiple correspondence analysis, cluster analysis and correlation tests. Qualitative data were analyzed through content analysis and the creation of thematic categories. Despite the concentration of activities directed at disease care, the Family Health Care Program carries out various activities related to the social determination of health, encompassing the entire spectrum of health promotion approaches (biological, behavioral, psychological, social and structural) and all major social determinants of health described in the literature. There was a significant difference related to the scope of the determinants being worked on in the units according to the area of the city. The description of the activities revealed the fragility of the initiatives and a disconnection with the organizational structure of the Family Health Care Program. The quantity and variety of initiatives related to social determinants of health attests to the program's potential to deal with the social determination of health. On the other hand, the fluidity of objectives and the 'out of the ordinary/extraordinary' characterization of the described initiatives raises concern about its sustainability as an integral part of the program's current operational model.

Polythermal investigation of viscosity of solution of metal carboxylates in VIK-grade mixed carboxylic acids: Yttrium and gadolinium carboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezhov, E.A.; Samatov, A.V.; Troyanovskii, L.V.

Kinematic viscosities have been measured for solutions of yttrium and gadolinium carboxylates in grade VIK mixed carboxylic acids (MCA). It has been established that the optimal fluidity of these metal carboxylate solutions for application to articles is reached at 333 K. A regression model has been developed to describe the concentration and temperature dependences of the viscosity of yttrium- and gadolinium-containing MCA solutions. 2 refs., 3 tabs.

The Categorical Stability of Gambling Motives Among Community-Recruited Gamblers: A Longitudinal Assessment.

PubMed

McGrath, Daniel S; Konkolÿ Thege, Barna

2018-03-01

Over the past decade, several motivational models have been proposed to explain the role of motives in gambling disorder. In the model captured by the four-factor Gambling Motives Questionnaire Financial (GMQ-F), gamblers are described as being primarily motivated to gamble for 'coping', 'enhancement', 'social', and 'financial' reasons. Although this model has received significant empirical support; to date, research assessing the role of motives in gambling disorder has been primarily cross-sectional in nature. Thus, the extent to which gambling motives remain stable over time has yet to be explored. In the current study, the stability versus fluidity of self-assessed gambling motives was investigated using the Quinte Longitudinal Study, a longitudinal dataset of gambling behaviour collected over 5 years. Gambling motives of 2795 gamblers were examined over all five annual assessments. The total proportion of gamblers who stayed in the same primary motive category across each of the 5 consecutive assessments was 22%, indicating substantial fluidity in category membership. Substantial movement between categories was seen for each GMQ-F group, as well as an additional group of non-classified motives. Logistic regression analyses suggest that greater resistance to gambling fallacies significantly predicted stability between the baseline assessment and a follow-up 1 year later, but gambling severity did not. Potential limitations in the study design and opportunities for future research are discussed.

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

PubMed Central

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-01-01

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration. PMID:28788223

Deoxycholic acid modulates cell death signaling through changes in mitochondrial membrane properties[S

PubMed Central

Sousa, Tânia; Castro, Rui E.; Pinto, Sandra N.; Coutinho, Ana; Lucas, Susana D.; Moreira, Rui; Rodrigues, Cecília M. P.; Prieto, Manuel; Fernandes, Fábio

2015-01-01

Cytotoxic bile acids, such as deoxycholic acid (DCA), are responsible for hepatocyte cell death during intrahepatic cholestasis. The mechanisms responsible for this effect are unclear, and recent studies conflict, pointing to either a modulation of plasma membrane structure or mitochondrial-mediated toxicity through perturbation of mitochondrial outer membrane (MOM) properties. We conducted a comprehensive comparative study of the impact of cytotoxic and cytoprotective bile acids on the membrane structure of different cellular compartments. We show that DCA increases the plasma membrane fluidity of hepatocytes to a minor extent, and that this effect is not correlated with the incidence of apoptosis. Additionally, plasma membrane fluidity recovers to normal values over time suggesting the presence of cellular compensatory mechanisms for this perturbation. Colocalization experiments in living cells confirmed the presence of bile acids within mitochondrial membranes. Experiments with active isolated mitochondria revealed that physiologically active concentrations of DCA change MOM order in a concentration- and time-dependent manner, and that these changes preceded the mitochondrial permeability transition. Importantly, these effects are not observed on liposomes mimicking MOM lipid composition, suggesting that DCA apoptotic activity depends on features of mitochondrial membranes that are absent in protein-free mimetic liposomes, such as the double-membrane structure, lipid asymmetry, or mitochondrial protein environment. In contrast, the mechanism of action of cytoprotective bile acids is likely not associated with changes in cellular membrane structure. PMID:26351365

Changes in the lipid composition of Bradyrhizobium cell envelope reveal a rapid response to water deficit involving lysophosphatidylethanolamine synthesis from phosphatidylethanolamine in outer membrane.

PubMed

Cesari, Adriana B; Paulucci, Natalia S; Biasutti, María A; Morales, Gustavo M; Dardanelli, Marta S

2018-06-02

We evaluate the behavior of the membrane of Bradyrhizobium sp. SEMIA6144 during adaptation to polyethylene glycol (PEG). A dehydrating effect on the morphology of the cell surface, as well as a fluidizing effect on the membrane was observed 10 min after PEG shock; however, the bacteria were able to restore optimal membrane fluidity. Shock for 1 h caused an increase of lysophosphatidylethanolamine in the outer membrane at the expense of phosphatidylcholine and phosphatidylethanolamine (PE), through an increase in phospholipase activity. The amount of lysophosphatidylethanolamine did not remain constant during PEG shock, but after 24 h the outer membrane was composed of large amounts of phosphatidylcholine and less amount of lysophosphatidylethanolamine similar to the control. The inner membrane composition was also modified after 1 h of shock, observing an increase of phosphatidylcholine at the expense of PE, the proportions of these phospholipids were then modified to reach 24 h of shock values similar to the control. Vesicles prepared with the lipids of cells exposed to 1 h shock presented higher rigidity compared to the control, indicating that changes in the composition of phospholipids after 1 h of shock restoring fluidity after the PEG effect and would allow cells to maintain surface morphology. Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

The Use of Stepper Motor-Controlled Proportional Valve for Fio2 Calculation in the Ventilator and its Control with Fuzzy Logic.

PubMed

Gölcük, Adem; Güler, İnan

2017-01-01

This article proposes the employment of a proportional valve that can calculate the amount of oxygen in the air to be given to patient in accordance with the amount of FiO 2 which is set from the control menu of the ventilation device. To actualize this, a stepper motor-controlled proportional valve was used. Two counts of valves were employed in order to control the gases with 2 bar pressure that came from both the oxygen and medical air tanks. Oxygen and medical air manometers alongside the pressure regulators were utilized to perform this task. It is a fuzzy-logic-based controller which calculates at what rate the proportional valves will be opened and closed for FiO 2 calculation. Fluidity and pressure of air given by the ventilation device were tested with a FlowMeter while the oxygen level was tested using the electronic lung model. The obtained results from the study revealed that stepper motor controlled proportional valve could be safely used in ventilation devices. In this article, it was indicated that fluidity and pressure control could be carried out with just two counts of proportional valve, which could be done with many solenoid valves, so this reduces the cost of ventilator, electrical power consumed by the ventilator, and the dimension of ventilator.

Metabolism of Fructooligosaccharides in Lactobacillus plantarum ST-III via Differential Gene Transcription and Alteration of Cell Membrane Fluidity

PubMed Central

Chen, Chen; Zhao, Guozhong

2015-01-01

Although fructooligosaccharides (FOS) can selectively stimulate the growth and activity of probiotics and beneficially modulate the balance of intestinal microbiota, knowledge of the molecular mechanism for FOS metabolism by probiotics is still limited. Here a combined transcriptomic and physiological approach was used to survey the global alterations that occurred during the logarithmic growth of Lactobacillus plantarum ST-III using FOS or glucose as the sole carbon source. A total of 363 genes were differentially transcribed; in particular, two gene clusters were induced by FOS. Gene inactivation revealed that both of the clusters participated in the metabolism of FOS, which were transported across the membrane by two phosphotransferase systems (PTSs) and were subsequently hydrolyzed by a β-fructofuranosidase (SacA) in the cytoplasm. Combining the measurements of the transcriptome- and membrane-related features, we discovered that the genes involved in the biosynthesis of fatty acids (FAs) were repressed in cells grown on FOS; as a result, the FA profiles were altered by shortening of the carbon chains, after which membrane fluidity increased in response to FOS transport and utilization. Furthermore, incremental production of acetate was observed in both the transcriptomic and the metabolic experiments. Our results provided new insights into gene transcription, the production of metabolites, and membrane alterations that could explain FOS metabolism in L. plantarum. PMID:26319882

Unraveling the concept of race in Brazil: issues for the Rio de Janeiro Cooperative Agreement site.

PubMed

Surratt, H L; Inciardi, J A

1998-01-01

Scholars throughout the Americas have spent much of the 20th century studying race and its meaning in Brazil. Racial identities in Brazil are dynamic concepts which can only be understood if situated and explored within the appropriate cultural context. Empirical evidence of the fluidity of racial identification quickly came to the authors' attention within the context of a prevention initiative targeting segments of the Rio de Janeiro population at high risk for HIV/AIDS. Because the main objective of this program was to slow the spread of AIDS through an intervention designed to promote behavioral change, comparisons of client data at the baseline and follow-up assessments form the core of the analyses. Through quality control procedures used to link client information collected at different points in time, it was revealed that 106 clients, or 12.5% of the follow-up sample, had changed their racial self-identification. The authors' attempts to engage project staff in a dialogue about the fluidity of racial identity among these clients have provided some insight into what might be called the "contextual redefinition" of race in Brazil. Within the framework of this study, the ramifications of this phenomenon are clear. Racial comparisons of HIV risk, sexual activity, drug use, and behavioral change, which are part and parcel of U.S.-based research, would appear to be of little utility in this setting.

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete.

PubMed

Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

2014-10-10

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

Electronic paramagnetic resonance investigation of the activity of Origanum vulgare L. essential oil on the Listeria monocytogenes membrane.

PubMed

Serio, A; Chiarini, M; Tettamanti, E; Paparella, A

2010-08-01

To evaluate the effect of oregano essential oil on Listeria monocytogenes cytoplasmic membrane. Nitroxide free-radical Electron Paramagnetic Resonance was applied on L. monocytogenes after 30 min exposure to oregano essential oil concentrations ranging from 0 to 1.25%. The impact of essential oil on the number of viable cells was evaluated by plate count. Growth dynamics of survivors in BHI and TSB were evaluated by turbidometry. After exposure to essential oil concentrations up to 0.50%, the membrane fluidity was changed and its order increased. When L. monocytogenes was exposed to higher concentrations, membrane order parameters slightly returned to the values of untreated cells. However, when the cells were exposed to EO in the presence of sodium azide, which impairs energy metabolism, the membrane fluidity was progressively enhanced, even at the lowest EO concentration (0.25%). Microbiological analyses confirmed a progressive reduction of viable count, at increasing essential oil concentrations. Both in BHI and TSB, the Lag phase length increased in treated cells with respect to controls, suggesting a cell damage recovery. The combined approach including microbiological and EPR analyses provided relevant information on membrane modification and cell response to essential oils. EPR approach was demonstrated to be an effective and helpful tool to comprehend the modifications exerted by essential oil on the bacterial membrane.

Haemato-protective influence of dietary fenugreek (Trigonella foenum-graecum L.) seeds is potentiated by onion (Allium cepa L.) in streptozotocin-induced diabetic rats.

PubMed

Pradeep, Seetur R; Srinivasan, Krishnapura

2018-02-01

We have recently reported the beneficial modulation of metabolic abnormalities and oxidative stress in diabetic rats by dietary fenugreek seeds and onion. This investigation evaluated the protective influence of dietary fenugreek seeds (100 g kg -1 ) and onion (30 g kg -1 ) on erythrocytes of streptozotocin-induced diabetic rats, through modulation of reduced haematological indices and antisickling potency. This study also evaluated the altered erythrocyte membrane lipid profile and beneficial countering of increased lipid peroxidation, osmotic fragility, along with reduced membrane fluidity and deformability, nitric oxide production and echinocyte formation. Dietary fenugreek seeds and onion appeared to counter the deformity and fragility of erythrocytes partially in diabetic rats by their antioxidant potential and hypocholesterolemic property. The antisickling potency of these spices was accomplished by a substantial decrease in echinocyte population and AGEs in diabetic rats. Further insight into the factors that might have reduced the fluidity of erythrocytes in diabetic rats revealed changes in the cholesterol: phospholipid ratio, fatty acid profile, and activities of membrane-bound enzymes. Dietary fenugreek seeds and onion offered a beneficial protective effect to the red blood cells, the effect being higher with fenugreek + onion. This is the first report on the hemato-protective influence of a nutraceutical food component in diabetic situation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The Lipopolysaccharide of Brucella abortus BvrS/BvrR Mutants Contains Lipid A Modifications and Has Higher Affinity for Bactericidal Cationic Peptides

PubMed Central

Manterola, Lorea; Moriyón, Ignacio; Moreno, Edgardo; Sola-Landa, Alberto; Weiss, David S.; Koch, Michel H. J.; Howe, Jörg; Brandenburg, Klaus; López-Goñi, Ignacio

2005-01-01

The two-component BvrS/BvrR system is essential for Brucella abortus virulence. It was shown previously that its dysfunction abrogates expression of some major outer membrane proteins and increases bactericidal peptide sensitivity. Here, we report that BvrS/BvrR mutants have increased surface hydrophobicity and susceptibility to killing by nonimmune serum. The bvrS and bvrR mutant lipopolysaccharides (LPSs) bound more polymyxin B, chimeras constructed with bvrS mutant cells and parental LPS showed augmented polymyxin B resistance, and, conversely, parental cells and bvrS mutant LPS chimeras were more sensitive and displayed polymyxin B-characteristic outer membrane lesions, implicating LPS as being responsible for the phenotype of the BvrS/BvrR mutants. No qualitative or quantitative changes were detected in other envelope and outer membrane components examined: periplasmic β(1-2) glucans, native hapten polysaccharide, and phospholipids. The LPS of the mutants was similar to parental LPS in O-polysaccharide polymerization and fine structure but showed both increased underacylated lipid A species and higher acyl-chain fluidity that correlated with polymyxin B binding. These lipid A changes did not alter LPS cytokine induction, showing that in contrast to other gram-negative pathogens, recognition by innate immune receptors is not decreased by these changes in LPS structure. Transcription of Brucella genes required for incorporating long acyl chains into lipid A (acpXL and lpxXL) or implicated in lipid A acylation control (bacA) was not affected. We propose that in Brucella the outer membrane homeostasis depends on the functioning of BvrS/BvrR. Accordingly, disruption of BvrS/BvrR damages the outer membrane, thus contributing to the severe attenuation manifested by bvrS and bvrR mutants. PMID:16077108

Analysis of Lipids and Lipid Rafts in Borrelia.

PubMed

Toledo, Alvaro; Huang, Zhen; Benach, Jorge L; London, Erwin

2018-01-01

Lipid rafts are membrane microdomains that are involved in cellular processes such as protein trafficking and signaling processes, and which play a fundamental role in membrane fluidity and budding. The lipid composition of the membrane and the biochemical characteristics of the lipids found within rafts define the ability of cells to form microdomains and compartmentalize the membrane. In this chapter, we describe the biophysical, biochemical, and molecular approaches used to define and characterize lipid rafts in the Lyme disease agent, Borrelia burgdorferi.

Coupling of lipid membrane elasticity and in-plane dynamics

NASA Astrophysics Data System (ADS)

Tsang, Kuan-Yu; Lai, Yei-Chen; Chiang, Yun-Wei; Chen, Yi-Fan

2017-07-01

Biomembranes exhibit liquid and solid features concomitantly with their in-plane fluidity and elasticity tightly regulated by cells. Here, we present experimental evidence supporting the existence of the dynamics-elasticity correlations for lipid membranes and propose a mechanism involving molecular packing densities to explain them. This paper thereby unifies, at the molecular level, the aspects of the continuum mechanics long used to model the two membrane features. This ultimately may elucidate the universal physical principles governing the cellular phenomena involving biomembranes.

High-resolution nanopatterning of biodegradable polylactide by thermal nanoimprint lithography using gas permeable mold

NASA Astrophysics Data System (ADS)

Takei, Satoshi; Hanabata, Makoto

2017-03-01

We report high-resolution (150 nm) nanopatterning of biodegradable polylactide by thermal nanoimprint lithography using dichloromethane as a volatile solvent for improving the liquidity and a porous cyclodextrin-based gas-permeable mold. This study demonstrates the high-resolution patterning of polylactic acid and other non-liquid functional materials with poor fluidity by thermal nanoimprinting. Such a patterning is expected to expand the utility of thermal nanoimprint lithography and fabricate non-liquid functional materials suitable for eco-friendly and biomedical applications.

Optimal distribution of science funding

NASA Astrophysics Data System (ADS)

Huang, Ding-wei

2018-07-01

We propose a new model to investigate the theoretical implications of a novel funding system. We introduce new parameters to model the accumulated advantage. We assume that all scientists are equal and follow the same regulations. The model presents three distinct regimes. In regime (I), the fluidity of funding is significant. The funding distribution is continuous. The concentration of funding is effectively suppressed. In both regimes (II) and (III), a small group of scientists emerges as a circle of elites. Large funding is acquired by a small number of scientists.

Cellular Effects of Perfluorinated Fatty Acids (PFDA).

DTIC Science & Technology

This is a proposal to investigate the effects of perfluorinated decanoic acid ( PFDA ) on the cell surface of liver cells and tissue. The major method...summarized as follows: (a) differentiated liver tissue culture cells in vitro do have the membrane fluidity affected by PFDA whereas undifferentiated, non...d) the effect on mobility occurs within 24 hours of exposure without further increase with time of exposure; (e) scanning EM demonstrates no gross structural abnormality of the surface as a result of the non-toxic levels of PFDA .

Improving the mixing performances of rice straw anaerobic digestion for higher biogas production by computational fluid dynamics (CFD) simulation.

PubMed

Shen, Fei; Tian, Libin; Yuan, Hairong; Pang, Yunzhi; Chen, Shulin; Zou, Dexun; Zhu, Baoning; Liu, Yanping; Li, Xiujin

2013-10-01

As a lignocellulose-based substrate for anaerobic digestion, rice straw is characterized by low density, high water absorbability, and poor fluidity. Its mixing performances in digestion are completely different from traditional substrates such as animal manures. Computational fluid dynamics (CFD) simulation was employed to investigate mixing performances and determine suitable stirring parameters for efficient biogas production from rice straw. The results from CFD simulation were applied in the anaerobic digestion tests to further investigate their reliability. The results indicated that the mixing performances could be improved by triple impellers with pitched blade, and complete mixing was easily achieved at the stirring rate of 80 rpm, as compared to 20-60 rpm. However, mixing could not be significantly improved when the stirring rate was further increased from 80 to 160 rpm. The simulation results agreed well with the experimental results. The determined mixing parameters could achieve the highest biogas yield of 370 mL (g TS)(-1) (729 mL (g TS(digested))(-1)) and 431 mL (g TS)(-1) (632 mL (g TS(digested))(-1)) with the shortest technical digestion time (T 80) of 46 days. The results obtained in this work could provide useful guides for the design and operation of biogas plants using rice straw as substrates.

Antifungal activity of secondary plant metabolites from potatoes (Solanum tuberosum L.): Glycoalkaloids and phenolic acids show synergistic effects.

PubMed

Sánchez-Maldonado, A F; Schieber, A; Gänzle, M G

2016-04-01

To study the antifungal effects of the potato secondary metabolites α-solanine, α-chaconine, solanidine and caffeic acid, alone or combined. Resistance to glycoalkaloids varied among the fungal species tested, as derived from minimum inhibitory concentrations assays. Synergistic antifungal activity between glycoalkaloids and phenolic compounds was found. Changes in the fluidity of fungal membranes caused by potato secondary plant metabolites were determined by calculation of the generalized polarization values. The results partially explained the synergistic effect between caffeic acid and α-chaconine and supported findings on membrane disruption mechanisms from previous studies on artificial membranes. LC/MS analysis was used to determine variability and relative amounts of sterols in the different fungal species. Results suggested that the sterol pattern of fungi is related to their resistance to potato glycoalkaloids and to their taxonomy. Fungal resistance to α-chaconine and possibly other glycoalkaloids is species dependent. α-Chaconine and caffeic acid show synergistic antifungal activity. The taxonomic classification and the sterol pattern play a role in fungal resistance to glycoalkaloids. Results improve the understanding of the antifungal mode of action of potato secondary metabolites, which is essential for their potential utilization as antifungal agents in nonfood systems. © 2016 The Society for Applied Microbiology.

Bactericidal activity of the human skin fatty acid cis-6-hexadecanoic acid on Staphylococcus aureus.

PubMed

Cartron, Michaël L; England, Simon R; Chiriac, Alina Iulia; Josten, Michaele; Turner, Robert; Rauter, Yvonne; Hurd, Alexander; Sahl, Hans-Georg; Jones, Simon; Foster, Simon J

2014-07-01

Human skin fatty acids are a potent aspect of our innate defenses, giving surface protection against potentially invasive organisms. They provide an important parameter in determining the ecology of the skin microflora, and alterations can lead to increased colonization by pathogens such as Staphylococcus aureus. Harnessing skin fatty acids may also give a new avenue of exploration in the generation of control measures against drug-resistant organisms. Despite their importance, the mechanism(s) whereby skin fatty acids kill bacteria has remained largely elusive. Here, we describe an analysis of the bactericidal effects of the major human skin fatty acid cis-6-hexadecenoic acid (C6H) on the human commensal and pathogen S. aureus. Several C6H concentration-dependent mechanisms were found. At high concentrations, C6H swiftly kills cells associated with a general loss of membrane integrity. However, C6H still kills at lower concentrations, acting through disruption of the proton motive force, an increase in membrane fluidity, and its effects on electron transfer. The design of analogues with altered bactericidal effects has begun to determine the structural constraints on activity and paves the way for the rational design of new antistaphylococcal agents. Copyright © 2014 Cartron et al.

Rheology and adhesion of poly(acrylic acid)/laponite nanocomposite hydrogels as biocompatible adhesives.

PubMed

Shen, Muxian; Li, Li; Sun, Yimin; Xu, Jun; Guo, Xuhong; Prud'homme, Robert K

2014-02-18

Biocompatible nanocomposite hydrogels (NC gels) consisting of poly(acrylic acid) (PAA) and nanosized clay (Laponite) were successfully synthesized by in situ free-radical polymerization of acrylic acid (AA) in aqueous solutions of Laponite. The obtained NC gels were uniform and transparent. Their viscosity, storage modulus G', and loss modulus G″ increased significantly upon increasing the content of Laponite and the dose of AA, while exhibiting a maximum with increasing the neutralization degree of AA. They showed tunable adhesion by changing the dose of Laponite and monomer as well as the neutralization degree of AA, as determined by 180° peel strength measurement. The maximal adhesion was shown when reaching a balance between cohesion and fluidity. A homemade Johnson-Kendall-Roberts (JKR) instrument was employed to study the surface adhesion behavior of the NC gels. The combination of peel strength, rheology, and JKR measurements offers the opportunity of insight into the mechanism of adhesion of hydrogels. The NC gels with tunable adhesion should be ideal candidates for dental adhesive, wound dressing, and tissue engineering.

Flavonoids in Microheterogeneous Media, Relationship between Their Relative Location and Their Reactivity towards Singlet Oxygen

PubMed Central

Günther, Germán; Berríos, Eduardo; Pizarro, Nancy; Valdés, Karina; Montero, Guillermo; Arriagada, Francisco; Morales, Javier

2015-01-01

In this work, the relationship between the molecular structure of three flavonoids (kaempferol, quercetin and morin), their relative location in microheterogeneous media (liposomes and erythrocyte membranes) and their reactivity against singlet oxygen was studied. The changes observed in membrane fluidity induced by the presence of these flavonoids and the influence of their lipophilicity/hydrophilicity on the antioxidant activity in lipid membranes were evaluated by means of fluorescent probes such as Laurdan and diphenylhexatriene (DPH). The small differences observed for the value of generalized polarization of Laurdan (GP) curves in function of the concentration of flavonoids, indicate that these three compounds promote similar alterations in liposomes and erythrocyte membranes. In addition, these compounds do not produce changes in fluorescence anisotropy of DPH, discarding their location in deeper regions of the lipid bilayer. The determined chemical reactivity sequence is similar in all the studied media (kaempferol < quercetin < morin). Morin is approximately 10 times more reactive than quercetin and 20 to 30 times greater than kaempferol, depending on the medium. PMID:26098745

Model lipid bilayers mimic non-specific interactions of gold nanoparticles with macrophage plasma membranes.

PubMed

Montis, Costanza; Generini, Viola; Boccalini, Giulia; Bergese, Paolo; Bani, Daniele; Berti, Debora

2018-04-15

Understanding the interaction between nanomaterials and biological interfaces is a key unmet goal that still hampers clinical translation of nanomedicine. Here we investigate and compare non-specific interaction of gold nanoparticles (AuNPs) with synthetic lipid and wild type macrophage membranes. A comprehensive data set was generated by systematically varying the structural and physicochemical properties of the AuNPs (size, shape, charge, surface functionalization) and of the synthetic membranes (composition, fluidity, bending properties and surface charge), which allowed to unveil the matching conditions for the interaction of the AuNPs with macrophage plasma membranes in vitro. This effort directly proved for the first time that synthetic bilayers can be set to mimic and predict with high fidelity key aspects of nanoparticle interaction with macrophage eukaryotic plasma membranes. It then allowed to model the experimental observations according to classical interface thermodynamics and in turn determine the paramount role played by non-specific contributions, primarily electrostatic, Van der Waals and bending energy, in driving nanoparticle-plasma membrane interactions. Copyright © 2018 Elsevier Inc. All rights reserved.

Omega-3 Fatty Acids Modulate TRPV4 Function through Plasma Membrane Remodeling.

PubMed

Caires, Rebeca; Sierra-Valdez, Francisco J; Millet, Jonathan R M; Herwig, Joshua D; Roan, Esra; Vásquez, Valeria; Cordero-Morales, Julio F

2017-10-03

Dietary consumption of ω-3 polyunsaturated fatty acids (PUFAs), present in fish oils, is known to improve the vascular response, but their molecular targets remain largely unknown. Activation of the TRPV4 channel has been implicated in endothelium-dependent vasorelaxation. Here, we studied the contribution of ω-3 PUFAs to TRPV4 function by precisely manipulating the fatty acid content in Caenorhabditis elegans. By genetically depriving the worms of PUFAs, we determined that the metabolism of ω-3 fatty acids is required for TRPV4 activity. Functional, lipid metabolome, and biophysical analyses demonstrated that ω-3 PUFAs enhance TRPV4 function in human endothelial cells and support the hypothesis that lipid metabolism and membrane remodeling regulate cell reactivity. We propose a model whereby the eicosanoid's epoxide group location increases membrane fluidity and influences the endothelial cell response by increasing TRPV4 channel activity. ω-3 PUFA-like molecules might be viable antihypertensive agents for targeting TRPV4 to reduce systemic blood pressure. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Adjusting membrane lipids under salt stress: the case of the moderate halophilic organism Halobacillus halophilus.

PubMed

Lopalco, Patrizia; Angelini, Roberto; Lobasso, Simona; Köcher, Saskia; Thompson, Melanie; Müller, Volker; Corcelli, Angela

2013-04-01

The lipid composition of Halobacillus halophilus was investigated by combined thin-layer chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses of the total lipid extract. Main polar lipids were found to be sulfoquinovosyldiacylglycerol and phosphatidylglycerol, while cardiolipin was a minor lipid together with phosphatidic acid, alanyl-phosphatidylglycerol and two not yet fully identified lipid components. In addition the analyses of residual lipids, associated with denatured proteins after the lipid extraction, revealed the presence of significant amounts of cardiolipin, indicating that it is a not readily extractable phospholipid. Post decay source mass spectrometry analyses allowed the determination of acyl chains of main lipid components. On increasing the culture medium salinity, an increase in the shorter chains and the presence of chain unsaturations were observed. These changes in the lipid core structures might compensate for the increase in packing and rigidity of phospholipid and sulfoglycolipid polar heads in high-salt medium, therefore contributing to the homeostasis of membrane fluidity and permeability in salt stress conditions. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Probing the Structures of Viral RNA Regulatory Elements with SHAPE and Related Methodologies

PubMed Central

Rausch, Jason W.; Sztuba-Solinska, Joanna; Le Grice, Stuart F. J.

2018-01-01

Viral RNAs were selected by evolution to possess maximum functionality in a minimal sequence. Depending on the classification of the virus and the type of RNA in question, viral RNAs must alternately be replicated, spliced, transcribed, transported from the nucleus into the cytoplasm, translated and/or packaged into nascent virions, and in most cases, provide the sequence and structural determinants to facilitate these processes. One consequence of this compact multifunctionality is that viral RNA structures can be exquisitely complex, often involving intermolecular interactions with RNA or protein, intramolecular interactions between sequence segments separated by several thousands of nucleotides, or specialized motifs such as pseudoknots or kissing loops. The fluidity of viral RNA structure can also present a challenge when attempting to characterize it, as genomic RNAs especially are likely to sample numerous conformations at various stages of the virus life cycle. Here we review advances in chemoenzymatic structure probing that have made it possible to address such challenges with respect to cis-acting elements, full-length viral genomes and long non-coding RNAs that play a major role in regulating viral gene expression. PMID:29375504

Milk fat globules: fatty acid composition, size and in vivo regulation of fat liquidity.

PubMed

Timmen, H; Patton, S

1988-07-01

Populations of large and small milk fat globules were isolated and analyzed to determine differences in fatty acid composition. Globule samples were obtained by centrifugation from milks of a herd and of individual animals produced under both pasture and barn feeding. Triacylglycerols of total globule lipids were prepared by thin layer chromatography and analyzed for fatty acid composition by gas chromatography. Using content of the acids in large globules as 100%, small globules contained fewer short-chain acids, -5.9%, less stearic acid, -22.7%, and more oleic acids, +4.6%, mean values for five trials. These differences are consistent with alternative use of short-chain acids or oleic acid converted from stearic acid to maintain liquidity at body temperature of milk fat globules and their precursors, intracellular lipid droplets. Stearyl-CoA desaturase (EC 1.14.99.5), which maintains fluidity of cellular endoplasmic reticulum membrane, is suggested to play a key role in regulating globule fat liquidity. Possible origins of differences between individual globules in fatty acid composition of their triacylglycerols are discussed.

Understanding the Interaction of Pluronics L61 and L64 with a DOPC Lipid Bilayer: An Atomistic Molecular Dynamics Study

DOE PAGES

Ileri Ercan, Nazar; Stroeve, Pieter; Tringe, Joseph W.; ...

2016-09-13

In this paper, we investigate the interactions of Pluronics L61 and L64 with a dioleylphosphatidylcholine (DOPC) lipid bilayer by atomistic molecular dynamics simulations using the all-atom OPLS force field. Our results show that the initial configuration of the polymer with respect to the bilayer determines its final conformation within the bilayer. When the polymer is initially placed at the lipid/water interface, we observe partial insertion of the polymer in a U-shaped conformation. On the other hand, when the polymer is centered at the bilayer, it stabilizes to a transmembrane state, which facilitates water transport across the bilayer. We show thatmore » membrane thickness decreases while its fluidity increases in the presence of Pluronics. When the polymer concentration inside the bilayer is high, pore formation is initiated with L64. Finally, our results show good agreement with existing experimental data and reveal that the hydrophilic/lipophilic balance of the polymer plays a critical role in the interaction mechanisms as well as in the dynamics of Pluronics with and within the bilayer.« less

Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas

DOE PAGES

Xu, J.; Liao, J.; Gyulassy, M.

2015-12-01

Here, we build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near “perfect fluid” like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. Moreover, a quantitative connection between the shear viscosity and jet transportmore » parameter is rigorously established within this framework. Finally, we deduce the T = 160-600 MeV dependence of the QGP’s η/s: its near vanishing value in the near T c regime is determined by the composition of E and M charges, it increases as T rises, and its high T limit is fixed by color screening scales.« less

Trans-cis isomerization of lipophilic dyes probing membrane microviscosity in biological membranes and in live cells.

PubMed

Chmyrov, Volodymyr; Spielmann, Thiemo; Hevekerl, Heike; Widengren, Jerker

2015-06-02

Membrane environment and fluidity can modulate the dynamics and interactions of membrane proteins and can thereby strongly influence the function of cells and organisms in general. In this work, we demonstrate that trans-cis isomerization of lipophilic dyes is a useful parameter to monitor packaging and fluidity of biomembranes. Fluorescence fluctuations, generated by trans-cis isomerization of the thiocarbocyanine dye Merocyanine 540 (MC540), were first analyzed by fluorescence correlation spectroscopy (FCS) in different alcohol solutions. Similar isomerization kinetics of MC540 in lipid vesicles could then also be monitored, and the influence of lipid polarity, membrane curvature, and cholesterol content was investigated. While no influence of membrane curvature and lipid polarity could be observed, a clear decrease in the isomerization rates could be observed with increasing cholesterol contents in the vesicle membranes. Finally, procedures to spatially map photoinduced and thermal isomerization rates on live cells by transient state (TRAST) imaging were established. On the basis of these procedures, MC540 isomerization was studied on live MCF7 cells, and TRAST images of the cells at different temperatures were found to reliably detect differences in the isomerization parameters. Our studies indicate that trans-cis isomerization is a useful parameter for probing membrane dynamics and that the TRAST imaging technique can provide spatial maps of photoinduced isomerization as well as both photoinduced and thermal back-isomerization, resolving differences in local membrane microviscosity in live cells.

MODEL AND CELL MEMBRANE PARTITIONING OF PERFLUOROOCTANESULFONATE IS INDEPENDENT OF THE LIPID CHAIN LENGTH

PubMed Central

Xie, Wei; Ludewig, Gabriele; Wang, Kai; Lehmler, Hans-Joachim

2009-01-01

Perfluorooctanesulfonic acid (PFOS) is a persistent environmental pollutant that may cause adverse health effects in humans and animals by interacting with and disturbing of the normal properties of biological lipid assemblies. To gain further insights into these interactions, we investigated the effect of PFOS potassium salt on dimyristoyl- (DMPC), dipalmitoyl- (DPPC) and distearoylphosphatidylcholine (DSPC) model membranes using fluorescence anisotropy measurements and differential scanning calorimetry (DSC) and on the cell membrane of HL-60 human leukemia cells and freshly isolated rat alveolar macrophages using fluorescence anisotropy measurements. PFOS caused a concentration-dependent decrease of the main phase transition temperature (Tm) and an increased peak width (ΔTw) in both the fluorescence anisotropy and the DSC experiments, with a rank order DMPC > DPPC > DSPC. PFOS caused a fluidization of the gel phase of all phosphatidylcholines investigated, but had the opposite effect on the liquid crystalline phase. The apparent partition coefficients of PFOS between the phosphatidylcholine bilayer and the bulk aqueous phase were largely independent of the phosphatidylcholine chain length and ranged from 4.4 × 104 to 8.8 × 104. PFOS also significantly increased the fluidity of membranes of cells. These findings suggest that PFOS readily partitions into lipid assemblies, independent of their composition, and may cause adverse biological effects by altering their fluidity in a manner that depends on the membrane cooperativity and state (e.g., gel versus liquid crystalline phase) of the lipid assembly. PMID:19932010

Effects of DHA-phospholipids, melatonin and tryptophan supplementation on erythrocyte membrane physico-chemical properties in elderly patients suffering from mild cognitive impairment.

PubMed

Cazzola, Roberta; Rondanelli, Mariangela; Faliva, Milena; Cestaro, Benvenuto

2012-12-01

A randomized, double-blind placebo-controlled clinical trial was carried out to assess the efficacy of a docosahexenoic acid (DHA)-phospholipids, melatonin and tryptophan supplemented diet in improving the erythrocyte oxidative stress, membrane fluidity and membrane-bound enzyme activities of elderly subjects suffering from mild cognitive impairment (MCI). These subjects were randomly assigned to the supplement group (11 subjects, 9F and 2M; age 85.3±5.3y) or placebo group (14-matched subjects, 11F and 3M; 86.1±6.5). The duration of the treatment was 12weeks. The placebo group showed no significant changes in erythrocyte membrane composition and function. The erythrocyte membranes of the supplement group showed a significant increase in eicosapentenoic acid, docosapentenoic acid and DHA concentrations and a significant decrease in arachidonic acid, malondialdehyde and lipofuscin levels. These changes in membrane composition resulted in an increase in the unsaturation index, membrane fluidity and acetylcholine esterase activity. Moreover, a significant increase in the ratio between reduced and oxidized glutathione was observed in the erythrocyte of the supplement group. Although this study is a preliminary investigation, we believe these findings to be of great speculative and interpretative interest to better understand the complex and multi-factorial mechanisms behind the possible links between diets, their functional components and possible molecular processes that contribute to increasing the risk of developing MCI and Alzheimer's. Copyright © 2012 Elsevier Inc. All rights reserved.

The in vitro comparative study of the effect of BPA, BPS, BPF and BPAF on human erythrocyte membrane; perturbations in membrane fluidity, alterations in conformational state and damage to proteins, changes in ATP level and Na+/K+ ATPase and AChE activities.

PubMed

Maćczak, Aneta; Duchnowicz, Piotr; Sicińska, Paulina; Koter-Michalak, Maria; Bukowska, Bożena; Michałowicz, Jaromir

2017-12-01

Bisphenols are massively used in the industry, and thus the exposure of biota including humans to these substances has been noted. In this study we have assessed the effect of BPA and its selected analogs, i.e. BPS, BPF and BPAF on membrane of human red blood cells, which is the first barrier that must be overcome by xenobiotics penetrating the cell, and is commonly utilized as a model in the investigation of the effect of different xenobiotics on various cell types. Red blood cells were incubated with BPA and its analogs in the concentrations ranging from 0.1 to 250 μg/ml for 4 h and 24 h. We have noted that the compounds studied altered membrane fluidity at its hydrophobic region, increased internal viscosity and osmotic fragility of the erythrocytes and altered conformational state of membrane proteins. Moreover, bisphenols examined increased thiol groups level, caused oxidative damage to membrane proteins, decreased ATP level, depleted the activity of Na+/K + ATPase and changed the activity of AChE in human red blood cells. It has been shown that the strongest changes were noted in cells treated with BPAF, while BPS caused the weakest (or none) alterations in the parameters studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tracking solvents in the skin through atomically resolved measurements of molecular mobility in intact stratum corneum

PubMed Central

Topgaard, Daniel; Sparr, Emma

2017-01-01

Solvents are commonly used in pharmaceutical and cosmetic formulations and sanitary products and cleansers. The uptake of solvent into the skin may change the molecular organization of skin lipids and proteins, which may in turn alter the protective skin barrier function. We herein examine the molecular effects of 10 different solvents on the outermost layer of skin, the stratum corneum (SC), using polarization transfer solid-state NMR on natural abundance 13C in intact SC. With this approach it is possible to characterize the molecular dynamics of solvent molecules when present inside intact SC and to simultaneously monitor the effects caused by the added solvent on SC lipids and protein components. All solvents investigated cause an increased fluidity of SC lipids, with the most prominent effects shown for the apolar hydrocarbon solvents and 2-propanol. However, no solvent other than water shows the ability to fluidize amino acids in the keratin filaments. The solvent molecules themselves show reduced molecular mobility when incorporated in the SC matrix. Changes in the molecular properties of the SC, and in particular alternation in the balance between solid and fluid SC components, may have significant influences on the macroscopic SC barrier properties as well as mechanical properties of the skin. Deepened understanding of molecular effects of foreign compounds in SC fluidity can therefore have strong impact on the development of skin products in pharmaceutical, cosmetic, and sanitary applications. PMID:28028209

Structure and properties of binder gels formed in the system Mg(OH)2-SiO2-H2O for immobilisation of Magnox sludge.

PubMed

Walling, Sam A; Kinoshita, Hajime; Bernal, Susan A; Collier, Nick C; Provis, John L

2015-05-07

A cementitious system for the immobilisation of magnesium rich Magnox sludge was produced by blending an Mg(OH)2 slurry with silica fume and an inorganic phosphate dispersant. The Mg(OH)2 was fully consumed after 28 days of curing, producing a disordered magnesium silicate hydrate (M-S-H) with cementitious properties. The structural characterisation of this M-S-H phase by (29)Si and (25)Mg MAS NMR showed clearly that it has strong nanostructural similarities to a disordered form of lizardite, and does not take on the talc-like structure as has been proposed in the past for M-S-H gels. The addition of sodium hexametaphosphate (NaPO3)6 as a dispersant enabled the material to be produced at a much lower water/solids ratio, while still maintaining the fluidity which is essential in practical applications, and producing a solid monolith. Significant retardation of M-S-H formation was observed with larger additions of phosphate, however the use of 1 wt% (NaPO3)6 was beneficial in increasing fluidity without a deleterious effect on M-S-H formation. This work has demonstrated the feasibility of using M-S-H as binder to structurally immobilise Magnox sludge, enabling the conversion of a waste into a cementitious binder with potentially very high waste loadings, and providing the first detailed nanostructural description of the material thus formed.

Membrane-associated stress proteins: more than simply chaperones.

PubMed

Horváth, Ibolya; Multhoff, Gabriele; Sonnleitner, Alois; Vígh, László

2008-01-01

The protein- and/or lipid-mediated association of chaperone proteins to membranes is a widespread phenomenon and implicated in a number of physiological and pathological events that were earlier partially or completely overlooked. A temporary association of certain HSPs with membranes can re-establish the fluidity and bilayer stability and thereby restore the membrane functionality during stress conditions. The fluidity and microdomain organization of membranes are decisive factors in the perception and transduction of stresses into signals that trigger the activation of specific HS genes. Conversely, the membrane association of HSPs may result in the inactivation of membrane-perturbing signals, thereby switch off the heat shock response. Interactions between certain HSPs and specific lipid microdomains ("rafts") might be a previously unrecognized means for the compartmentalization of HSPs to specific signaling platforms, where key signaling proteins are known to be concentrated. Any modulations of the membranes, especially the raft-lipid composition of the cells can alter the extracellular release and thus the immuno-stimulatory activity of certain HSPs. Reliable techniques, allowing mapping of the composition and dynamics of lipid microdomains and simultaneously the spatio-temporal localization of HSPs in and near the plasma membrane can provide suitable means with which to address fundamental questions, such as how HSPs are transported to and translocated through the plasma membrane. The possession of such information is critical if we are to target the membrane association principles of HSPs for successful drug development in most various diseases.

Fluorescent Probe Study of AOT Vesicle Membranes and Their Alteration upon Addition of Aniline or the Aniline Dimer p-Aminodiphenylamine (PADPA).

PubMed

Iwasaki, Fumihiko; Luginbühl, Sandra; Suga, Keishi; Walde, Peter; Umakoshi, Hiroshi

2017-02-28

Artificial vesicles formed from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in aqueous solution are used successfully as additives for enzymatic oligomerizations or polymerizations of aniline or the aniline dimer p-aminodiphenylamine (PADPA) under slightly acidic conditions (e.g., pH 4.3 with horseradish peroxidase and hydrogen peroxide as oxidants). In these systems, the reactions occur membrane surface-confined. Therefore, (i) the physicochemical properties of the vesicle membrane and (ii) the interaction of aniline or PADPA with the AOT membrane play crucial roles in the progress and final outcome of the reactions. For this reason, the properties of AOT vesicles with and without added aniline or PADPA were investigated by using two fluorescent membrane probes: 1,6-diphenyl-1,3,5-hexatriene (DPH) and 6-lauroyl-2-dimethylaminonaphthalene (Laurdan). DPH and Laurdan were used as "sensors" of the membrane fluidity, surface polarity, and membrane phase state. Moreover, the effect of hexanol, alone or in combination with aniline or PADPA, as a possible modifier of the AOT membrane, was also studied with the aim of evaluating whether the membrane fluidity and surface polarity is altered significantly by hexanol, which, in turn, may have an influence on the mentioned types of reactions. The data obtained indicate that the AOT vesicle membrane at room temperature and pH 4.3 (0.1 M NaH 2 PO 4 ) is more fluid and has a more polar surface than in the case of fluid phospholipid vesicle membranes formed from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). Furthermore, the fluorescence measurements indicate that mixed AOT-hexanol membranes are less fluid than pure AOT membranes and that they have a lower surface polarity than pure AOT membranes. PADPA strongly binds to AOT and to mixed AOT/hexanol membranes and leads to drastic changes in the membrane properties (decrease in fluidity and surface polarity), resulting in Laurdan fluorescence spectra, which are characteristic for intramembrane phase separations (coexistence of ordered and disordered domains). This means that highly fluid AOT membranes transform upon the addition of PADPA into membranes that have ordered domains. Although the relevance of this finding for the enzymatic oligomerization of PADPA is not yet clear, it is also of interest if one likes to use heterogeneous vesicle membranes as additives for carrying out membrane surface-confined reactions that do not necessarily involve PADPA as a reactant.

Cholesterol modulates open probability and desensitization of NMDA receptors

PubMed Central

Korinek, Miloslav; Vyklicky, Vojtech; Borovska, Jirina; Lichnerova, Katarina; Kaniakova, Martina; Krausova, Barbora; Krusek, Jan; Balik, Ales; Smejkalova, Tereza; Horak, Martin; Vyklicky, Ladislav

2015-01-01

NMDA receptors (NMDARs) are glutamate-gated ion channels that mediate excitatory neurotransmission in the CNS. Although these receptors are in direct contact with plasma membrane, lipid–NMDAR interactions are little understood. In the present study, we aimed at characterizing the effect of cholesterol on the ionotropic glutamate receptors. Whole-cell current responses induced by fast application of NMDA in cultured rat cerebellar granule cells (CGCs) were almost abolished (reduced to 3%) and the relative degree of receptor desensitization was increased (by seven-fold) after acute cholesterol depletion by methyl-β-cyclodextrin. Both of these effects were fully reversible by cholesterol repletion. By contrast, the responses mediated by AMPA/kainate receptors were not affected by cholesterol depletion. Similar results were obtained in CGCs after chronic inhibition of cholesterol biosynthesis by simvastatin and acute enzymatic cholesterol degradation to 4-cholesten-3-one by cholesterol oxidase. Fluorescence anisotropy measurements showed that membrane fluidity increased after methyl-β-cyclodextrin pretreatment. However, no change in fluidity was observed after cholesterol enzymatic degradation, suggesting that the effect of cholesterol on NMDARs is not mediated by changes in membrane fluidity. Our data show that diminution of NMDAR responses by cholesterol depletion is the result of a reduction of the open probability, whereas the increase in receptor desensitization is the result of an increase in the rate constant of entry into the desensitized state. Surface NMDAR population, agonist affinity, single-channel conductance and open time were not altered in cholesterol-depleted CGCs. The results of our experiments show that cholesterol is a strong endogenous modulator of NMDARs. Key points NMDA receptors (NMDARs) are tetrameric cation channels permeable to calcium; they mediate excitatory synaptic transmission in the CNS and their excessive activation can lead to neurodegeneration. Although these receptors are in direct contact with plasma membrane, lipid–NMDAR interactions are little understood. Using cultured rat cerebellar granule cells, we show that acute and chronic pretreatments resulting in cell cholesterol depletion profoundly diminish NMDAR responses and increase NMDAR desensitization, and also that cholesterol enrichment potentiates NMDAR responses; however, cholesterol manipulation has no effect on the amplitude of AMPA/kainate receptor responses. Diminution of NMDAR responses by cholesterol depletion is the result of a reduction of the ion channel open probability, whereas the increase in receptor desensitization is the result of an increase in the rate constant of entry into the desensitized state. These results demonstrate the physiological role of membrane lipids in the modulation of NMDAR activity. PMID:25651798

Detection of Liposome Membrane Viscosity Perturbations with Ratiometric Molecular Rotors

PubMed Central

Nipper, Matthew E.; Dakanali, Marianna; Theodorakis, Emmanuel

2011-01-01

Molecular rotors are a form of fluorescent intramolecular charge-transfer complexes that can undergo intramolecular twisting motion upon photoexcitation. Twisted-state formation leads to non-radiative relaxation that competes with fluorescence emission. In bulk solutions, these molecules exhibit a viscosity-dependent quantum yield. On the molecular scale, the fluorescence emission is a function of the local free volume, which in turn is related to the local microviscosity. Membrane viscosity, and the inverse; fluidity, are characteristic terms used to describe the ease of movement withing the membrane. Often, changes in membrane viscosity govern intracellular processes and are indicative of a disease state. Molecular rotors have been used to investigate viscosity changes in liposomes and cells, but accuracy is affected by local concentration gradients and sample optical properties. We have developed self-calibrating ratiometric molecular rotors to overcome this challenge and integrated the new molecules into a DLPC liposome model exposed to the membrane-fluidizing agent propanol. We show that the ratiometric emission intensity linearly decreases with the pentanol exposure and that the ratiometric intensity is widely independent of the total liposome concentration. Conversely, dye concentration inside liposomes influences the sensitivity of the system. We suggest that the new self-calibrating dyes can be used for real-time viscosity sensing in liposome systems with the advantages of lifetime measurements, but with low-cost steady-state instrumentation. PMID:21354253

Phase transitions in methyl parben doped dipalmitoyl phosphatidylethanolamine vesicles

NASA Astrophysics Data System (ADS)

Panicker, Lata

2013-02-01

Influence of the preservative, methyl paraben (MPB), on the thermal properties of dipalmitoyl phosphatidylethanolamine (DPPE) vesicles was investigated using DSC. DSC measurement of the lipid acyl chain melting transition in DPPE membrane doped with MPB, showed MPB concentration dependant modifications in the membrane thermal properties. The interesting findings are: (1) the presence of parabens increases the membrane fluidity. (2) the MPB molecules seem to be present in the aqueous bilayer interfacial region intercalated between the neighboring lipid polar headgroup (3) high concentration of MPB favored formation of crystalline and glassy phases.

Research on and Application to BH-HTC High Density Cementing Slurry System on Tarim Region

NASA Astrophysics Data System (ADS)

Yuanhong, Song; Fei, Gao; Jianyong, He; Qixiang, Yang; Jiang, Yang; Xia, Liu

2017-08-01

A large section of salt bed is contented in Tarim region Piedmont which constructs complex geological conditions. For high-pressure gas well cementing difficulties from the region, high density cement slurry system has been researched through reasonable level of particle size distribution and second weighting up. The results of laboratory tests and field applications show that the high density cementing slurry system is available to Tarim region cementing because this system has a well performance in slurry stability, gas breakthrough control, fluidity, water loss, and strength.

The Study on Development of Light-Weight Foamed Mortar for Tunnel Backfill

NASA Astrophysics Data System (ADS)

Ma, Sang-Joon; Kang, Eun-Gu; Kim, Dong-Min

This study was intended to develop the Light-Weight Foamed Mortar which is used for NATM Composite lining backfill. In the wake of the study, the mixing method which satisfies the requirements for compressive strength, permeability coefficient, fluidity, specific gravity and settlement was developed and moreover field applicability was verified through the model test. Thus the mixing of Light-Weight Foamed Mortar developed in this study is expected to be applicable to NATM Composite lining, thereby making commitment to improving the stability and drainage performance of lining.

Specific binding of 15 HETE to lymphocytes. Effects on the fluidity of plasmatic membranes.

PubMed

Mexmain, S; Gualde, N; Aldigier, J C; Motta, C; Chable-Rabinovitch, H; Rigaud, M

1984-01-01

Specific binding of mouse lymphocytes for 15 HETE was examined by incubating cells with [14C]-15 HETE, 1 X 10(-8) to 1 X 10(-10)M. It was observed that the specific binding of radiolabeled 15 HETE is a function of time, of temperature and is modified by Ca2+ and dithiothreitol. When a fluorescent probe was embedded in the phospholipid core of the lymphocyte membrane and its motion analysed by fluorescence polarization, it was observed that 15 HETE increases the viscosity of the plasmatic membrane.

Pathological levels of glucosylceramide change the biophysical properties of artificial and cell membranes.

PubMed

Varela, Ana R P; Ventura, Ana E; Carreira, Ana C; Fedorov, Aleksander; Futerman, Anthony H; Prieto, Manuel; Silva, Liana C

2016-12-21

Glucosylceramide (GlcCer) plays an active role in the regulation of various cellular events. Moreover, GlcCer is also a key modulator of membrane biophysical properties, which might be linked to the mechanism of its biological action. In order to understand the biophysical implications of GlcCer on membranes of living cells, we first studied the effect of GlcCer on artificial membranes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol). Using an array of biophysical methods, we demonstrate that at lower GlcCer/Chol ratios, GlcCer stabilizes SM/Chol-enriched liquid-ordered domains. However, upon decreasing the Chol content, GlcCer significantly increased membrane order through the formation of gel domains. Changes in pH disturbed the packing properties of GlcCer-containing membranes, leading to an increase in membrane fluidity and reduced membrane electronegativity. To address the biophysical impact of GlcCer in biological membranes, studies were performed in wild type and in fibroblasts treated with conduritol-B-epoxide (CBE), which causes intracellular GlcCer accumulation, and in fibroblasts from patients with type I Gaucher disease (GD). Decreased membrane fluidity was observed in cells containing higher levels of GlcCer, such as in CBE-treated and GD cells. Together, we demonstrate that elevated GlcCer levels change the biophysical properties of cellular membranes, which might compromise membrane-associated cellular events and be of relevance for understanding the pathology of diseases, such as GD, in which GlcCer accumulates at high levels.

Liposomes composed of unsaturated lipids for membrane modification of human erythrocytes.

PubMed

Stoll, Christoph; Holovati, Jelena L; Acker, Jason P; Wolkers, Willem F

2011-01-01

Previous studies have shown that certain saturated lipids protect red blood cells (RBCs) during hypothermic storage but provide little protection during freezing or freeze-drying, whereas various unsaturated lipids destabilize RBCs during hypothermic storage but protect during freezing and freeze-drying. The protective effect of liposomes has been attributed to membrane modifications. We have previously shown that cholesterol exchange and lipid transfer between liposomes composed of saturated lipids and RBCs critically depends on the length of the lipid acyl chains. In this study the effect of unsaturated lipids with differences in their number of unsaturated bonds (18:0/18:1, 18:1/18:1, 18:2/18:2) on RBC membrane properties has been studied. RBCs were incubated in the presence of liposomes and both the liposomal and RBC fraction were analyzed by Fourier transform infrared spectroscopy (FTIR) after incubation. The liposomes caused an increase in RBC membrane conformational disorder at suprazero temperatures. The fluidizing effect of the liposomes on the RBC membranes, however, was found to be similar for the different lipids irrespective of their unsaturation level. The gel to liquid crystalline phase transition temperature of the liposomes increased after incubation with RBCs. RBC membrane fluidity increased linearly during the first 8 hours of incubation in the presence of liposomes. The increase in RBC membrane fluidity was found to be temperature dependent and displayed Arrhenius behaviour between 20 and 40°C, with an activation energy of 88 kJ mol⁻¹. Taken together, liposomes composed of unsaturated lipids increase RBC membrane conformational disorder, which could explain their cryoprotective action.

Polycyclic aromatic hydrocarbons in model bacterial membranes - Langmuir monolayer studies.

PubMed

Broniatowski, Marcin; Binczycka, Martyna; Wójcik, Aneta; Flasiński, Michał; Wydro, Paweł

2017-12-01

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are persistent organic pollutants which due to their limited biodegradability accumulate in soils where their increased presence can lead to the impoverishment of the decomposer organisms. As very hydrophobic PAHs easily penetrate cellular membranes of soil bacteria and can be incorporated therein, changing the membrane fluidity and other functions which in consequence can lead to the death of the organism. The structure and size of PAH molecule can be crucial for its membrane activity; however the correlation between PAH structure and its interaction with phospholipids have not been investigated so far. In our studies we applied phospholipid Langmuir monolayers as model bacterial membranes and investigated how the incorporation of six structurally different PAH molecules change the membrane texture and physical properties. In our studies we registered surface pressure and surface potential isotherms upon the monolayer compression, visualized the monolayer texture with the application of Brewster angle microscopy and searched the ordering of the film-forming molecules with molecular resolution with the application of grazing incidence X-ray diffraction (GIXD) method. It turned out that the phospholipid-PAH interactions are strictly structure dependent. Four and five-ring PAHs of the angular or cluster geometry can be incorporated into the model membranes changing profoundly their textures and fluidity; whereas linear or large cluster PAHs cannot be incorporated and separate from the lipid matrix. The observed phenomena were explained based on structural similarities of the applied PAHs with membrane steroids and hopanoids. Copyright © 2017. Published by Elsevier B.V.

A role for the thermal environment in defining co-stimulation requirements for CD4+ T cell activation

PubMed Central

Zynda, Evan R; Grimm, Melissa J; Yuan, Min; Zhong, Lingwen; Mace, Thomas A; Capitano, Maegan; Ostberg, Julie R; Lee, Kelvin P; Pralle, Arnd; Repasky, Elizabeth A

2015-01-01

Maintenance of normal core body temperature is vigorously defended by long conserved, neurovascular homeostatic mechanisms that assist in heat dissipation during prolonged, heat generating exercise or exposure to warm environments. Moreover, during febrile episodes, body temperature can be significantly elevated for at least several hours at a time. Thus, as blood cells circulate throughout the body, physiologically relevant variations in surrounding tissue temperature can occur; moreover, shifts in core temperature occur during daily circadian cycles. This study has addressed the fundamental question of whether the threshold of stimulation needed to activate lymphocytes is influenced by temperature increases associated with physiologically relevant increases in temperature. We report that the need for co-stimulation of CD4+ T cells via CD28 ligation for the production of IL-2 is significantly reduced when cells are exposed to fever-range temperature. Moreover, even in the presence of sufficient CD28 ligation, provision of extra heat further increases IL-2 production. Additional in vivo and in vitro data (using both thermal and chemical modulation of membrane fluidity) support the hypothesis that the mechanism by which temperature modulates co-stimulation is linked to increases in membrane fluidity and membrane macromolecular clustering in the plasma membrane. Thermally-regulated changes in plasma membrane organization in response to physiological increases in temperature may assist in the geographical control of lymphocyte activation, i.e., stimulating activation in lymph nodes rather than in cooler surface regions, and further, may temporarily and reversibly enable CD4+ T cells to become more quickly and easily activated during times of infection during fever. PMID:26131730

Oxidative Stress and Erythrocyte Membrane Alterations in Children with Autism: Correlation with Clinical Features.

PubMed

Ghezzo, Alessandro; Visconti, Paola; Abruzzo, Provvidenza M; Bolotta, Alessandra; Ferreri, Carla; Gobbi, Giuseppe; Malisardi, Gemma; Manfredini, Stefano; Marini, Marina; Nanetti, Laura; Pipitone, Emanuela; Raffaelli, Francesca; Resca, Federica; Vignini, Arianna; Mazzanti, Laura

2013-01-01

It has been suggested that oxidative stress may play a role in the pathogenesis of Autism Spectrum Disorders (ASD), but the literature reports somewhat contradictory results. To further investigate the issue, we evaluated a high number of peripheral oxidative stress parameters, and some related issues such as erythrocyte membrane functional features and lipid composition. Twenty-one autistic children (Au) aged 5 to 12 years, were gender and age-matched with 20 typically developing children (TD). Erythrocyte thiobarbituric acid reactive substances, urinary isoprostane and hexanoyl-lysine adduct levels were elevated in Au, thus confirming the occurrence of an imbalance of the redox status of Au, whilst other oxidative stress markers or associated parameters (urinary 8-oxo-dG, plasma radical absorbance capacity and carbonyl groups, erythrocyte superoxide dismutase and catalase activities) were unchanged. A very significant reduction of Na(+)/K(+)-ATPase activity (-66%, p<0.0001), a reduction of erythrocyte membrane fluidity and alteration in erythrocyte fatty acid membrane profile (increase in monounsaturated fatty acids, decrease in EPA and DHA-ω3 with a consequent increase in ω6/ω3 ratio) were found in Au compared to TD, without change in membrane sialic acid content. Some Au clinical features appear to be correlated with these findings; in particular, hyperactivity score appears to be related with some parameters of the lipidomic profile and membrane fluidity. Oxidative stress and erythrocyte membrane alterations may play a role in the pathogenesis of ASD and prompt the development of palliative therapeutic protocols. Moreover, the marked decrease in NKA could be potentially utilized as a peripheral biomarker of ASD.

Mechanism of permeability-enhancing effect of EDTA and boric acid on the corneal penetration of 4-[1-hydroxy-1-methylethyl]-2-propyl-1-[4-[2-[tetrazole-5-yl]phenyl]phenyl] methylimidazole-5-carboxylic acid monohydrate (CS-088).

PubMed

Kikuchi, Takayuki; Suzuki, Masahiko; Kusai, Akira; Iseki, Ken; Sasaki, Hitoshi; Nakashima, Kenichiro

2005-08-11

This study was conducted to clarify the penetration properties of 4-[1-hydroxy-1-methylethyl]-2-propyl-1-[4-[2-[tetrazole-5-yl]phenyl]phenyl]methylimidazole-5-carboxylic acid monohydrate (CS-088), an ophthalmic agent, and the mechanism of the permeability-enhancing effect of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088. In the absence of additives, corneal permeability decreased with increasing concentration of CS-088 as CS-088 monomers self-associate to form dimers. Presence of EDTA/boric acid caused no significant changes in the physicochemical properties of CS-088, the apparent partition coefficient or the mean particle size of CS-088. EDTA/boric acid induced only a slight change in the zeta potential of liposomes used as a model of the biological membrane. On the other hand, EDTA/boric acid significantly increased membrane fluidity of liposomes, whereas other buffering agents tested did not. This effect was synergistic and concentration-dependent for both EDTA and boric acid as was observed in in vitro corneal penetration of CS-088. In accordance with the result, the rate of CS-088 permeation into the liposomes significantly increased by the addition of EDTA/boric acid. Therefore, it was demonstrated that EDTA/boric acid promotes corneal penetration of CS-088 through the transcellular pathway by increasing membrane fluidity. Conversely, other buffering agents decreased corneal permeability of CS-088 by inducing further self-association of CS-088 aggregates.

Customizing semen preservation protocols for individual dogs and individual species: sperm preservation beyond the state of the art.

PubMed

Farstad, W

2012-12-01

Sperm quality can be variable in morphometric and physiological attributes between males of different species, between males within species subtypes reared under different environmental conditions, between ejaculates of the same male or even between sperm populations within an ejaculate. Clinical semen evaluation is based on evaluation of whole ejaculates, which is not a chemically or physiologically well-defined entity, rather a collection of heterogeneous subpopulations giving different measurements and possessing different fertilizing potential. Identification of subpopulations with different motility patterns is important as well as characterizing the subtle structural changes underlying the motility differences observed. The ability to identify populations of sperm responding rapidly or failing to progress through the capacitation process may have clinical applications. Studies of lipid-phase fluidity of sperm membranes, mathematical modelling of membrane ion transport, role of modifying components and detergent-resistant microdomains are of particular interest. When customizing extenders to ejaculates from cryosensitive males or species, a thorough knowledge of species sperm membrane physiology and an assessment of the individual ejaculate's sperm populations are necessary. Structural differences have been found in sperm membranes between fox species with different cryosurvival potential of their spermatozoa. Supplementation of lipids and detergents in cryoextenders may influence membrane fluidity of the surviving spermatozoa in a species-dependent manner and influence capacitation. Immobilization of sperm prior to cryopreservation with subsequent slow release of sperm in the female genital tract may be a way to prolong the fertile life of sperm. In canids with a long oocyte maturation time, delayed capacitation may be beneficial. © 2012 Blackwell Verlag GmbH.

Using a patterned grating structure to create lipid bilayer platforms insensitive to air bubbles.

PubMed

Han, Chung-Ta; Chao, Ling

2015-01-07

Supported lipid bilayers (SLBs) have been used for various biosensing applications. The bilayer structure enables embedded lipid membrane species to maintain their native orientation, and the two-dimensional fluidity is crucial for numerous biomolecular interactions to occur. The platform integrated with a microfluidic device for reagent transport and exchange has great potential to be applied with surface analytical tools. However, SLBs can easily be destroyed by air bubbles during assay reagent transport and exchange. Here, we created a patterned obstacle grating structured surface in a microfluidic channel to protect SLBs from being destroyed by air bubbles. Unlike all of the previous approaches using chemical modification or adding protection layers to strengthen lipid bilayers, the uniqueness of this approach is that it uses the patterned obstacles to physically trap water above the bilayers to prevent the air-water interface from directly coming into contact with and peeling the bilayers. We showed that our platform with certain grating geometry criteria can provide promising protection to SLBs from air bubbles. The required obstacle distance was found to decrease when we increased the air-bubble movement speed. In addition, the interaction assay results from streptavidin and biotinylated lipids in the confined SLBs suggested that receptors at the SLBs retained the interaction ability after air-bubble treatment. The results showed that the developed SLB platform can preserve both high membrane fluidity and high accessibility to the outside environment, which have never been simultaneously achieved before. Incorporating the built platforms with some surface analytical tools could open the bottleneck of building highly robust in vitro cell-membrane-related bioassays.

Cannabinoid receptor signalling in neurodegenerative diseases: a potential role for membrane fluidity disturbance

PubMed Central

Maccarrone, M; Bernardi, G; Agrò, A Finazzi; Centonze, D

2011-01-01

Type-1 cannabinoid receptor (CB1) is the most abundant G-protein-coupled receptor (GPCR) in the brain. CB1 and its endogenous agonists, the so-called ‘endocannabinoids (eCBs)’, belong to an ancient neurosignalling system that plays important functions in neurodegenerative and neuroinflammatory disorders like Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and multiple sclerosis. For this reason, research on the therapeutic potential of drugs modulating the endogenous tone of eCBs is very intense. Several GPCRs reside within subdomains of the plasma membranes that contain high concentrations of cholesterol: the lipid rafts. Here, the hypothesis that changes in membrane fluidity alter function of the endocannabinoid system, as well as progression of particular neurodegenerative diseases, is described. To this end, the impact of membrane cholesterol on membrane properties and hence on neurodegenerative diseases, as well as on CB1 signalling in vitro and on CB1-dependent neurotransmission within the striatum, is discussed. Overall, present evidence points to the membrane environment as a critical regulator of signal transduction triggered by CB1, and calls for further studies aimed at better clarifying the contribution of membrane lipids to eCBs signalling. The results of these investigations might be exploited also for the development of novel therapeutics able to combat disorders associated with abnormal activity of CB1. LINKED ARTICLES This article is part of a themed issue on Cannabinoids in Biology and Medicine. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.163.issue-7 PMID:21323908

Fullerene inhibits benzo(a)pyrene Efflux from Cyprinus carpio hepatocytes by affecting cell membrane fluidity and P-glycoprotein expression.

PubMed

Chen, Qiqing; Hu, Xialin; Wang, Rui; Yuan, Jin; Yin, Daqiang

2016-05-01

P-Glycoprotein (P-gp) can protect cells by pumping out toxic compounds, and has been found widely expressed in fish tissues. Here, we illustrate the P-gp efflux ability for benzo(a)pyrene (BaP) in the hepatocytes of common carp (Cyprinus carpio) after exposing to fullerene aqueous suspension (nC60). The results revealed that nC60 increased the membrane fluidity by decreasing the ratio of saturated to unsaturated fatty acids, and increased the cholesterol contents. These findings, combined with 10-38% and 70-75% down-regulation of P-gp mRNA and protein respectively, suggested that nC60 caused inhibition on P-gp efflux transport system. Therefore, we further investigated the cellular efflux ability for BaP. Results showed unequivocally that nC60 is a potent P-gp inhibitor. The retaining BaP amounts after efflux were elevated by 1.7-2.8 fold during the 10 day exposure. Meanwhile, 5mg/L humic acid (one of the important fractions of natural organic matter, which is ubiquitous in aquatic environment) alleviated the nC60 damage to hepatocytes in terms of oxidative damage, cholesterol increment, and P-gp content reduction; and finally attenuated the suppressed P-gp efflux ability. Collectively, this study provides the first evidence of nC60 toxicity to P-gp functionality in fish and illustrates the possible mechanism of the suppressed P-gp efflux ability for BaP. Copyright © 2016 Elsevier B.V. All rights reserved.

IFITM proteins-cellular inhibitors of viral entry.

PubMed

Smith, Se; Weston, S; Kellam, P; Marsh, M

2014-02-01

Interferon inducible transmembrane (IFITM) proteins are a recently discovered family of cellular anti-viral proteins that restrict the replication of a number of enveloped and non-enveloped viruses. IFITM proteins are located in the plasma membrane and endosomal membranes, the main portals of entry for many viruses. Biochemical and membrane fusion studies suggest IFITM proteins have the ability to inhibit viral entry, possibly by modulating the fluidity of cellular membranes. Here we discuss the IFITM proteins, recent work on their mode of action, and future directions for research. Copyright © 2014 Elsevier B.V. All rights reserved.

Beyond the dichotomy: six religious views of homosexuality.

PubMed

Moon, Dawne

2014-01-01

Using published theological and scholarly evidence, this article disrupts the stereotypical "born gay"/"sinful choice" dichotomy widely assumed to characterize religious views of homosexuality in the United States. It argues that we need to keep moral questions separate from questions about the fixity or fluidity of sexual orientation. Rather than two, American Christian and Jewish views of homosexuality can been seen on a range from the "God Hates Fags" view through "Love the Sinner, Hate the Sin," "We Don't Talk About That," "They Can't Help It," "God's Good Gift," and a queer-theological view of the "Godly Calling."

Prolonged Preservation of Human Platelets for Combat Casualty Care.

DTIC Science & Technology

1994-04-15

membrane fluidity. 5) Flurbiprofen : Flurbiprofen is an inhibitor of the cyclooxygenase enzyme and thus blocks this arm of the arachidonic acid cascade...were previously demonstrated individually to effectively block agonist stimulated activation. These agents are quinacrine, flurbiprofen and...1 0 02 1 Quinacrine 0 0 25 13 0 67 28 5nM 0 25 38 0 67 56 50nM 0 25 37 0 44 61 .5M 0 6 25 0 38 28 Flurbiprofen 0 0 6 0 0 63 13 10nM 0 6 0 0 56 19 .lM

Ruptures of vulnerability: Linda Stein's Knight Series.

PubMed

Bible, Ann Vollmann

2010-01-01

Drawing on the work of Monique Wittig, this article understands Linda Stein's Knight Series as a lacunary writing communicating both her challenges to come to representation and her creative registration of subjectivity. The argument is grounded in an exploration of the rich interplay of power and vulnerability across the series as against the discourse of escapist fashion. Specifically, Stein's critical contradictions of inside and outside, conflated temporality, disjunctions between decoration and abstraction, and fluidity of sex and gender are examined. The discussion is elaborated through consideration of the work of Julia Kristeva, Elizabeth Grosz, and Hayao Miyazaki.

Nearly Perfect Fluidity in a High Temperature Superconductor

DOE PAGES

Rameau, J. D.; Reber, T. J.; Yang, H. -B.; ...

2014-10-13

Perfect fluids are characterized as having the smallest ratio of shear viscosity to entropy density, η/s, consistent with quantum uncertainty and causality. So far, nearly perfect fluids have only been observed in the quark-gluon plasma and in unitary atomic Fermi gases, exotic systems that are amongst the hottest and coldest objects in the known universe, respectively. We use angle resolved photoemission spectroscopy to measure the temperature dependence of an electronic analog of η/s in an optimally doped cuprate high-temperature superconductor, finding it too is a nearly perfect fluid around, and above, its superconducting transition temperature T c.

Nearly perfect fluidity in a high-temperature superconductor

NASA Astrophysics Data System (ADS)

Rameau, J. D.; Reber, T. J.; Yang, H.-B.; Akhanjee, S.; Gu, G. D.; Johnson, P. D.; Campbell, S.

2014-10-01

Perfect fluids are characterized as having the smallest ratio of shear viscosity to entropy density, η /s, consistent with quantum uncertainty and causality. So far, nearly perfect fluids have only been observed in the quark-gluon plasma and in unitary atomic Fermi gases, exotic systems that are amongst the hottest and coldest objects in the known universe, respectively. We use angle resolved photoemission spectroscopy to measure the temperature dependence of an electronic analog of η /s in an optimally doped cuprate high-temperature superconductor, finding it too is a nearly perfect fluid around, and above, its superconducting transition temperature Tc.

Effects of Current Guides Destruction at Ultra-fast Acceleration of Macrobodies

NASA Astrophysics Data System (ADS)

Kataev, V. N.; Boriskin, A. S.; Golosov, S. N.; Demidov, V. A.; Klimashov, M. V.; Korolev, P. V.; Makartsev, G. F.; Pikar, A. S.; Russkov, A. S.; Shapovalov, E. V.; Shibitov, Yu. M.

2006-08-01

The paper is devoted to discussion of current guides destruction effects in different accelerators: thermal-electric and electro-magnetic rail accelerator at macrobodies acceleration value of 108-109 m/s2. Experimental results with thermal-electric accelerators powering from megajoule capacitor battery and helical magneto-cumulative generator MCG-100 at currents up to 3.5 MA are analyzed. The process of rails destruction at railgun at pressure magnetic field excess over the limit of metal fluidity is presented. Methods of efficiency coefficient increase of capacitive storage energy transmission to kinetic energy of accelerating body are discussed.

Fluidity of the Subsyndromal Phenomenology of Borderline Personality Disorder Over 16 Years of Prospective Follow-Up.

PubMed

Zanarini, Mary C; Frankenburg, Frances R; Reich, D Bradford; Fitzmaurice, Garrett M

2016-07-01

The purpose of this study was to determine the cumulative rates of 2- and 4-year remission, and the recurrences that follow them, of 24 symptoms of borderline personality disorder over 16 years of prospective follow-up. A total of 290 inpatients meeting rigorous criteria for borderline personality disorder and 72 axis II comparison subjects were assessed during their index admission using a series of semistructured diagnostic interviews. The same instruments were readministered at eight contiguous 2-year time periods. The 12 acute symptoms (e.g., self-mutilation, help-seeking suicide attempts) of borderline personality disorder were more likely to remit for a period of 2 years and for a period of 4 years than the 12 temperamental symptoms (e.g., chronic anger/frequent angry acts, intolerance of aloneness) of this disorder. They were also less likely to recur after a remission lasting 2 years or a remission lasting 4 years. Taken together, the symptoms of borderline personality disorder are quite fluid, with remissions and recurrences being common. However, the more clinically urgent acute symptoms of borderline personality disorder seem to have a better prognosis than the less turbulent temperamental symptoms of the disorder.

Fluidity of the Subsyndromal Phenomenology of Borderline Personality Disorder over 16 Years of Prospective Follow-up

PubMed Central

Zanarini, Mary C.; Frankenburg, Frances R.; Reich, D. Bradford; Fitzmaurice, Garrett M.

2016-01-01

Objective The purpose of this study was to determine the cumulative rates of two and four-year remission, and the recurrences that follow them, of 24 symptoms of borderline personality disorder over 16 years of prospective follow-up. Method 290 inpatients meeting rigorous criteria for borderline personality disorder and 72 axis II comparison subjects were assessed during their index admission using a series of semistructured diagnostic interviews. The same instruments were readministered at eight contiguous two-year time periods. Results The 12 acute symptoms (e.g., self-mutilation, help-seeking suicide attempts) of borderline personality disorder were more likely to remit for a period of two years and for a period of four years than the 12 temperamental symptoms (e.g., chronic anger/frequent angry acts, intolerance of aloneness) of this disorder. They were also less likely to recur after a remission lasting two years or a remission lasting four years. Conclusions Taken together, the symptoms of borderline personality disorder are quite fluid, with remissions and recurrences being common. However, the more clinically urgent acute symptoms of borderline personality disorder seem to have a better prognosis than the less turbulent temperamental symptoms of the disorder. PMID:26869248

Sulfone-carbonate ternary electrolyte with further increased capacity retention and burn resistance for high voltage lithium ion batteries

NASA Astrophysics Data System (ADS)

Xue, Leigang; Lee, Seung-Yul; Zhao, Zuofeng; Angell, C. Austen

2015-11-01

Safety and high energy density are the two focus issues for current lithium ion batteries. For safety, it has been demonstrated that sulfone electrolytes are much less flammable than the prevailing all-carbonate type, and they are also promising for high voltage batteries due to the high oxidization resistance. However, the high melting points and viscosities greatly restricted their application. Based on our previous work on use of fluidity-enhancing cosolvents to make binary sulfone-carbonate electrolytes, we report here a three-component system that is more conductive and should be even less flammable while additionally having better low temperature stability. The conductivity-viscosity relations have been determined for this electrolyte and are comparable to those of the "standard" carbonate electrolyte. The additional component also produces much improved capacity retention for the LiNi0.5Mn1.5O4 cathode. As with carbonate electrolytes, increase of temperature to 55 °C leads to rapid capacity decrease during cycling, but the capacity loss is due to the salt, not the solvent. The high discharge capacity observed at 25 °C when LiBF4 replaces LiPF6, is fully retained at 55 °C.

Folding dynamics of linear emulsion polymers into 3D architectures

NASA Astrophysics Data System (ADS)

McMullen, Angus; Bargteil, Dylan; Brujic, Jasna

Colloidal polymers have been limited to inflexible, solid colloids. Here we show that the fluidity of emulsion droplets allows for the self-assembly of flexible droplet chains, which can subsequently be folded into 3D structures via secondary interactions. We achieve this using DNA-guided interactions, to initially form the chain, and then program its folding pathways. When two emulsion droplets labeled with complementary DNA meet, the balance of hybridization energy and droplet deformation yields an equilibrium patch size. Therefore, the concentration of DNA on the surface determines the number of droplet-droplet bonds in the assembly. We find that 96 % of bound droplets successfully self-assemble into chains. Droplet binding is a stochastic process, following a Poisson distribution of lengths. Since the fluid droplets can rearrange, we compare the dynamics of emulsion chains to that of polymers. We also trigger secondary interactions along the chain, causing the formation of specific loops or compact clusters. This approach will allow us to fold our emulsion polymers into a wide array of soft structures, giving us a powerful biomimetic colloidal system to investigate protein folding on the mesoscopic scale. This work was supported by the NSF MRSEC Program (DMR-0820341).

Comparative Lipidomic Profiling of S. cerevisiae and Four Other Hemiascomycetous Yeasts

PubMed Central

Hein, Eva-Maria; Hayen, Heiko

2012-01-01

Glycerophospholipids (GP) are the building blocks of cellular membranes and play essential roles in cell compartmentation, membrane fluidity or apoptosis. In addition, GPs are sources for multifunctional second messengers. Whereas the genome and proteome of the most intensively studied eukaryotic model organism, the baker’s yeast (Saccharomyces cerevisiae), are well characterized, the analysis of its lipid composition is still at the beginning. Moreover, different yeast species can be distinguished on the DNA, RNA and protein level, but it is currently unknown if they can also be differentiated by determination of their GP pattern. Therefore, the GP compositions of five different yeast strains, grown under identical environmental conditions, were elucidated using high performance liquid chromatography coupled to negative electrospray ionization-hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry in single and multistage mode. Using this approach, relative quantification of more than 100 molecular species belonging to nine GP classes was achieved. The comparative lipidomic profiling of Saccharomyces cerevisiae, Saccharomyces bayanus, Kluyveromyces thermotolerans, Pichia angusta, and Yarrowia lipolytica revealed characteristic GP profiles for each strain. However, genetically related yeast strains show similarities in their GP compositions, e.g., Saccharomyces cerevisiae and Saccharomyces bayanus. PMID:24957378

Catching a Wave: The Hypnosis-Sensitive Transference-Based Treatment of Dissociative Identity Disorder (DID).

PubMed

Brenner, Ira

2018-01-01

In this article, I will describe the way in which I work with enactment-prone dissociative patients in the transference. This approach requires an appreciation of the phenomena of hypnosis and the auto-hypnotic aspects of some forms of dissociation. Essentially, I learn from the patient and my interactions with the patient how hypnotic phenomena and auto-hypnotic defenses manifest themselves in the therapeutic relationship in order both to understand them and ultimately to bring them under conscious control. Because of the fluidity and turbulence of these states, I use the analogy of catching a wave, in which timing and balance are essential, albeit elusive factors in effecting a successful treatment. The importance of having experience with many patients, attending conferences, seeking supervision, and undergoing one's own therapy will be also discussed as important prerequisites for the clinician endeavoring to utilize this type of approach. This preparation, this quest for such a "balance," is modeled after the so-called tripartite model of training employed in psychoanalytic training institutes. I will offer clinical material to illustrate this approach, which I have described as "psychoactive psychotherapy." In such treatments, the clinician may be taken by surprise and is likely to be thrown "off balance" from time to time. The mutually shared understanding of such moments is essential to regaining clinical balance in the therapeutic setting, and can lead to if not create important turning points in the treatment process.

[Description and evaluation of creative thinking in preterm low birth weight infants].

PubMed

Parisi, L; Di Filippo, T; Firrigno, L; La Grutta, S; Testa, D; Roccella, M

2007-04-01

Since the 1950s, the problem of how to evaluate creativity has been addressed in studies on the definition of measurement criteria and on the relationship between intelligence and creative thinking. Many revealed cognitive and relational disorders in preterm infants, particularly in preterm very low birth weight infants (birth weight <1500 g) and in infants with serious complications. This study describes the development of creative thinking in a group of children born preterm. The study sample was 43 children (21 males, 22 females; age range 6-11 years), regularly attending school, born with low birth weight (1050-2450 g) at 29-32 weeks gestational age, and compared with a control group with birth weight >2500 g. The test battery included: Torrance Test of Creative Thinking (TCTT); WISC-R intelligence test; Goodenough Human Figure Drawing Test. Statistical analysis (Mann-Whitney U test) showed a statistically significant difference (P>0.05) between the 2 groups; scores for figure originality, figure fluidity and figure elaboration were consistently higher in the control group. Within the low birth weight group, there was a significant correlation (Spearman r) between verbal IQ and verbal fluidity and verbal flexibility subscale scores and between IQ performance and figure elaboration. Scores on the figure drawing tests showed higher creative ability in the control group. In children born preterm with low birth weight, emotive dynamics and flow of affection may influence the channels of communication between child and family. The low figure originality subscale scores support the hypothesis that psychodynamic and relational factors (worry about the preterm condition, overprotective behaviour by parents and others) could lead to diminished autonomy, flexibility and manipulatory interest in the child.

Structural study of the effects of mutations in proteins to identify the molecular basis of the loss of local structural fluidity leading to the onset of autoimmune diseases.

PubMed

Ali, Ananya; Ghosh, Semanti; Bagchi, Angshuman

2017-02-26

Protein-Protein Interactions (PPIs) are crucial in most of the biological processes and PPI dysfunctions are known to be associated with the onsets of various diseases. One of such diseases is the auto-immune disease. Auto-immune diseases are one among the less studied group of diseases with very high mortality rates. Thus, we tried to correlate the appearances of mutations with their probable biochemical basis of the molecular mechanisms leading to the onset of the disease phenotypes. We compared the effects of the Single Amino Acid Variants (SAVs) in the wild type and mutated proteins to identify any structural deformities that might lead to altered PPIs leading ultimately to disease onset. For this we used Relative Solvent Accessibility (RSA) as a spatial parameter to compare the structural perturbation in mutated and wild type proteins. We observed that the mutations were capable to increase intra-chain PPIs whereas inter-chain PPIs would remain mostly unaltered. This might lead to more intra-molecular friction causing a deleterious alteration of protein's normal function. A Lyapunov exponent analysis, using the altered RSA values due to polymorphic and disease causing mutations, revealed polymorphic mutations have a positive mean value for the Lyapunov exponent while disease causing mutations have a negative mean value. Thus, local spatial stochasticity has been lost due to disease causing mutations, indicating a loss of structural fluidity. The amino acid conversion plot also showed a clear tendency of altered surface patch residue conversion propensity than polymorphic conversions. So far, this is the first report that compares the effects of different kinds of mutations (disease and non-disease causing polymorphic mutations) in the onset of autoimmune diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Improvement of Transmembrane Transport Mechanism Study of Imperatorin on P-Glycoprotein-Mediated Drug Transport.

PubMed

Liao, Zheng-Gen; Tang, Tao; Guan, Xue-Jing; Dong, Wei; Zhang, Jing; Zhao, Guo-Wei; Yang, Ming; Liang, Xin-Li

2016-11-24

P-glycoprotein (P-gp) affects the transport of many drugs; including puerarin and vincristine. Our previous study demonstrated that imperatorin increased the intestinal absorption of puerarin and vincristine by inhibiting P-gp-mediated drug efflux. However; the underlying mechanism was not known. The present study investigated the mechanism by which imperatorin promotes P-gp-mediated drug transport. We used molecular docking to predict the binding force between imperatorin and P-gp and the effect of imperatorin on P-gp activity. P-gp efflux activity and P-gp ATPase activity were measured using a rhodamine 123 (Rh-123) accumulation assay and a Pgp-Glo™ assay; respectively. The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to assess cellular membrane fluidity in MDCK-MDR1 cells. Western blotting was used to analyze the effect of imperatorin on P-gp expression; and P-gp mRNA levels were assessed by qRT-PCR. Molecular docking results demonstrated that the binding force between imperatorin and P-gp was much weaker than the force between P-gp and verapamil (a P-gp substrate). Imperatorin activated P-gp ATPase activity; which had a role in the inhibition of P-gp activity. Imperatorin promoted Rh-123 accumulation in MDCK-MDR1 cells and decreased cellular membrane fluidity. Western blotting demonstrated that imperatorin inhibited P-gp expression; and qRT-PCR revealed that imperatorin down-regulated P-gp (MDR1) gene expression. Imperatorin decreased P-gp-mediated drug efflux by inhibiting P-gp activity and the expression of P-gp mRNA and protein. Our results suggest that imperatorin could down-regulate P-gp expression to overcome multidrug resistance in tumors.

Effects of clary sage oil and its main components, linalool and linalyl acetate, on the plasma membrane of Candida albicans: an in vivo EPR study.

PubMed

Blaskó, Ágnes; Gazdag, Zoltán; Gróf, Pál; Máté, Gábor; Sárosi, Szilvia; Krisch, Judit; Vágvölgyi, Csaba; Makszin, Lilla; Pesti, Miklós

2017-02-01

The effects of clary sage (Salvia sclarea L.) oil (CS-oil), and its two main components, linalool (Lol) and linalyl acetate (LA), on cells of the eukaryotic human pathogen yeast Candida albicans were studied. Dynamic and thermodynamic properties of the plasma membrane were investigated by electron paramagnetic resonance (EPR) spectroscopy, with 5-doxylstearic acid (5-SASL) and 16-SASL as spin labels. The monitoring of the head group regions with 5-SASL revealed break-point frequency decrease in a temperature dependent manner of the plasma membrane between 9.55 and 13.15 °C in untreated, in CS-oil-, Lol- and LA-treated membranes. The results suggest a significant increase in fluidity of the treated plasma membranes close to the head groups. Comparison of the results observed with the two spin labels demonstrated that CS-oil and LA induced an increased level of fluidization at both depths of the plasma membrane. Whereas Lol treatment induced a less (1 %) ordered bilayer organization in the superficial regions and an increased (10 %) order of the membrane leaflet in deeper layers. Acute toxicity tests and EPR results indicated that both the apoptotic and the effects exerted on the plasma membrane fluidity depended on the composition and chemical structure of the examined materials. In comparison with the control, treatment with CS-oil, Lol or LA induced 13.0, 12.3 and 26.4 % loss respectively, of the metabolites absorbing at 260 nm, as a biological consequence of the plasma membrane fluidizing effects. Our results confirmed that clary sage oil causes plasma membrane perturbations which leads to cell apoptosis process.

The direct anti-MRSA effect of emodin via damaging cell membrane.

PubMed

Liu, Ming; Peng, Wei; Qin, Rongxin; Yan, Zifei; Cen, Yanyan; Zheng, Xinchuan; Pan, Xichun; Jiang, Weiwei; Li, Bin; Li, Xiaoli; Zhou, Hong

2015-09-01

Methicillin-resistant Staphylococcus aureus (MRSA) has become an important bacterium for nosocomial infection. Only a few antibiotics can be effective against MRSA. Therefore, searching for new drugs against MRSA is important. Herein, anti-MRSA activities of emodin and its mechanisms were investigated. Firstly, in vitro antimicrobial activity was investigated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-growth curve, and multipassage resistance testing was performed. Secondly, protection of emodin on mice survival and blood bacterial load in mice challenged with lethal or sublethal dose of MRSA were investigated. Subsequently, the influences of emodin on the bacterial morphology, messenger RNA (mRNA) expressions related to cell wall synthesis and lysis, β-lactamase activity, drug accumulation, membrane fluidity, and integrity were performed to investigate its mechanisms. Lastly, in vitro cytotoxicity assay were performed using the 3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) method. The results showed MICs and MBCs of emodin against MRSA252 and 36 clinical MRSA strains were among 2-8 and 4-32 μg/mL, respectively. There was no MIC increase for emodin during 20 passages. In vivo, emodin dose-dependently protected mice challenged with lethal dose of MRSA and decreased bacterial load in mice challenged with sublethal dose of MRSA. Morphology observation showed emodin might disrupt cell wall and membrane of MRSA. Although emodin had no influence on genes related to cell wall synthesis and lysis as well as β-lactamase activity and drug accumulation, emodin reduced membrane fluidity and disrupted membrane integrity. Based on the fact that emodin had no significant cytotoxicity against mammalian cells, it could be further investigated as a membrane-damage bactericide against MRSA in the future.

Hyaluron Filler Containing Lidocaine on a CPM Basis for Lip Augmentation: Reports from Practical Experience.

PubMed

Fischer, Tanja C; Sattler, Gerhard; Gauglitz, Gerd G

2016-06-01

Lip augmentation with hyaluronic acid fillers is established. As monophasic polydensified hyaluronic acid products with variable density, CPM-HAL1 (Belotero Balance Lidocaine, Merz Aesthetics, Raleigh, NC) and CPM-HAL2 (Belotero Intense Lidocaine, Merz Aesthetics, Raleigh, NC) are qualified for beautification and particularly natural-looking rejuvenation, respectively. The aim of this article was to assess the handling and outcome of lip augmentation using the lidocaine-containing hyaluronic acid fillers, CPM-HAL1 and CPM-HAL2. Data were documented from patients who received lip augmentation by means of beautification and/or rejuvenation using CPM-HAL1 and/or CPM-HAL2. Observation period was 4 months, with assessment of natural outcome, evenness, distribution, fluidity, handling, malleability, tolerability, as well as patient satisfaction and pain. A total of 146 patients from 21 German centers participated. Physicians rated natural outcome and evenness as good or very good for more than 95% of patients. Distribution, fluidity, handling, and malleability were assessed for both fillers as good or very good in more than 91% of patients. At every evaluation point, more than 93% of patients were very or very much satisfied with the product. A total of 125 patients (85.6%) experienced transient injection-related side effects. Pain intensity during the procedure was mild (2.72 ± 1.72 on the 0-10 pain assessment scale) and abated markedly within 30 minutes (0.42 ± 0.57). Lip augmentation with hyaluronic acid fillers produced a long-term cosmetic result. Due to the lidocaine content, procedural pain was low and transient. Accordingly, a high degree of patient satisfaction was achieved that was maintained throughout the observation period. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Interactions of plaunotol with bacterial membranes.

PubMed

Koga, T; Watanabe, H; Kawada, H; Takahashi, K; Utsui, Y; Domon, H; Ishii, C; Narita, T; Yasuda, H

1998-08-01

Plaunotol, a cytoprotective antiulcer agent, has a bactericidal effect against Helicobacter pylori, which may result from interaction of this compound with the bacterial cell membrane. The purpose of the present study was to confirm that plaunotol interacts with the H. pylori membrane. Membrane fluidities were measured using two stearic acid spin labels, namely 5-doxyl-stearic acid (in which the nitroxide group is located in the upper portion of the bacterial cell membrane) and 16-doxyl-stearic acid methyl ester (in which the nitroxide group is located deeper in the bacterial cell membrane), by means of electron spin resonance. The membrane fluidities of plaunotol-treated cells were significantly increased in the measurements made using the two spin labels. We also attempted to isolate plaunotol-resistant H. pylori in vitro by two different methods. To assess the level of resistance that could be reached, H. pylori was passaged five times on an agar plate containing subinhibitory concentrations of plaunotol or metronidazole. To measure the rate of development of resistance, H. pylori was grown with subinhibitory concentrations (0.25 x MIC) of plaunotol or metronidazole, and quantitatively plated on to medium containing 4 x MIC of the compounds. This treatment was repeated once more. No plaunotol-resistant colonies were selected by the two methods. H. pylori developed resistance to metronidazole easily and at a relatively high rate. The mechanism by which plaunotol directly fluidizes and destroys the H. pylori membrane might make it difficult for this organism to develop resistance to plaunotol. It was confirmed that the bactericidal effects of plaunotol were also shown against Staphylococcus aureus, Streptococcus pneumoniae, Neisseria gonorrhoeae, Moraxella catarrhalis and Haemophilus influenzae. No such effect was seen against Escherichia coli and Pseudomonas aeruginosa.

Terpenes increase the lipid dynamics in the Leishmania plasma membrane at concentrations similar to their IC50 values.

PubMed

Camargos, Heverton Silva; Moreira, Rodrigo Alves; Mendanha, Sebastião Antonio; Fernandes, Kelly Souza; Dorta, Miriam Leandro; Alonso, Antonio

2014-01-01

Although many terpenes have shown antitumor, antibacterial, antifungal, and antiparasitic activity, the mechanism of action is not well established. Electron paramagnetic resonance (EPR) spectroscopy of the spin-labeled 5-doxyl stearic acid revealed remarkable fluidity increases in the plasma membrane of terpene-treated Leishmania amazonensis promastigotes. For an antiproliferative activity assay using 5×10(6) parasites/mL, the sesquiterpene nerolidol and the monoterpenes (+)-limonene, α-terpineol and 1,8-cineole inhibited the growth of the parasites with IC50 values of 0.008, 0.549, 0.678 and 4.697 mM, respectively. The IC50 values of these terpenes increased as the parasite concentration used in the cytotoxicity assay increased, and this behavior was examined using a theoretical treatment of the experimental data. Cytotoxicity tests with the same parasite concentration as in the EPR experiments revealed a correlation between the IC50 values of the terpenes and the concentrations at which they altered the membrane fluidity. In addition, the terpenes induced small amounts of cell lysis (4-9%) at their respective IC50 values. For assays with high cell concentrations (2×10(9) parasites/mL), the incorporation of terpene into the cell membrane was very fast, and the IC50 values observed for 24 h and 5 min-incubation periods were not significantly different. Taken together, these results suggest that terpene cytotoxicity is associated with the attack on the plasma membrane of the parasite. The in vitro cytotoxicity of nerolidol was similar to that of miltefosine, and nerolidol has high hydrophobicity; thus, nerolidol might be used in drug delivery systems, such as lipid nanoparticles to treat leishmaniasis.

Terpenes Increase the Lipid Dynamics in the Leishmania Plasma Membrane at Concentrations Similar to Their IC50 Values

PubMed Central

Camargos, Heverton Silva; Moreira, Rodrigo Alves; Mendanha, Sebastião Antonio; Fernandes, Kelly Souza; Dorta, Miriam Leandro; Alonso, Antonio

2014-01-01

Although many terpenes have shown antitumor, antibacterial, antifungal, and antiparasitic activity, the mechanism of action is not well established. Electron paramagnetic resonance (EPR) spectroscopy of the spin-labeled 5-doxyl stearic acid revealed remarkable fluidity increases in the plasma membrane of terpene-treated Leishmania amazonensis promastigotes. For an antiproliferative activity assay using 5×106 parasites/mL, the sesquiterpene nerolidol and the monoterpenes (+)-limonene, α-terpineol and 1,8-cineole inhibited the growth of the parasites with IC50 values of 0.008, 0.549, 0.678 and 4.697 mM, respectively. The IC50 values of these terpenes increased as the parasite concentration used in the cytotoxicity assay increased, and this behavior was examined using a theoretical treatment of the experimental data. Cytotoxicity tests with the same parasite concentration as in the EPR experiments revealed a correlation between the IC50 values of the terpenes and the concentrations at which they altered the membrane fluidity. In addition, the terpenes induced small amounts of cell lysis (4–9%) at their respective IC50 values. For assays with high cell concentrations (2×109 parasites/mL), the incorporation of terpene into the cell membrane was very fast, and the IC50 values observed for 24 h and 5 min-incubation periods were not significantly different. Taken together, these results suggest that terpene cytotoxicity is associated with the attack on the plasma membrane of the parasite. The in vitro cytotoxicity of nerolidol was similar to that of miltefosine, and nerolidol has high hydrophobicity; thus, nerolidol might be used in drug delivery systems, such as lipid nanoparticles to treat leishmaniasis. PMID:25101672

Detrimental Effects of Non-Functional Spermatozoa on the Freezability of Functional Spermatozoa from Boar Ejaculate

PubMed Central

Martinez-Alborcia, Maria J.; Valverde, Anthony; Parrilla, Inmaculada; Vazquez, Juan M.; Martinez, Emilio A.; Roca, Jordi

2012-01-01

In the present study, the impact of non-functional spermatozoa on the cryopreservation success of functional boar spermatozoa was evaluated. Fifteen sperm-rich ejaculate fractions collected from five fertile boars were frozen with different proportions of induced non-functional sperm (0 –native semen sample-, 25, 50 and 75% non-functional spermatozoa). After thawing, the recovery of motile and viable spermatozoa was assessed, and the functional of the spermatozoa was evaluated from plasma membrane fluidity and intracellular reactive oxygen species (ROS) generation upon exposure to capacitation conditions. In addition, the lipid peroxidation of the plasma membrane was assessed by the indirect measurement of malondialdehyde (MDA) generation. The normalized (with respect to a native semen sample) sperm motility (assessed by CASA) and viability (cytometrically assessed after staining with Hoechst 33342, propidium iodide and fluorescein-conjugated peanut agglutinin) decreased (p<0.01) as the proportion of functional spermatozoa in the semen samples before freezing decreased, irrespective of the semen donor. However, the magnitude of the effect differed (p<0.01) among boars. Moreover, semen samples with the largest non-functional sperm subpopulation before freezing showed the highest (p<0.01) levels of MDA after thawing. The thawed viable spermatozoa of semen samples with a high proportion of non-functional spermatozoa before freezing were also functionally different from those of samples with a low proportion of non-functional spermatozoa. These differences consisted of higher (p<0.01) levels of intracellular ROS generation (assessed with 5-(and-6) chloromethyl-20,70-dichlorodihydrofluorescein diacetate acetyl ester; CM-H2DCFDA) and increased (p<0.01) membrane fluidity (assessed with Merocyanine 540). These findings indicate that non-functional spermatozoa in the semen samples before freezing negatively influence the freezability of functional spermatozoa. PMID:22567165

Oxidative Stress and Erythrocyte Membrane Alterations in Children with Autism: Correlation with Clinical Features

PubMed Central

Visconti, Paola; Bolotta, Alessandra; Ferreri, Carla; Gobbi, Giuseppe; Malisardi, Gemma; Manfredini, Stefano; Marini, Marina; Nanetti, Laura; Pipitone, Emanuela; Raffaelli, Francesca; Resca, Federica; Mazzanti, Laura

2013-01-01

It has been suggested that oxidative stress may play a role in the pathogenesis of Autism Spectrum Disorders (ASD), but the literature reports somewhat contradictory results. To further investigate the issue, we evaluated a high number of peripheral oxidative stress parameters, and some related issues such as erythrocyte membrane functional features and lipid composition. Twenty-one autistic children (Au) aged 5 to 12 years, were gender and age-matched with 20 typically developing children (TD). Erythrocyte thiobarbituric acid reactive substances, urinary isoprostane and hexanoyl-lysine adduct levels were elevated in Au, thus confirming the occurrence of an imbalance of the redox status of Au, whilst other oxidative stress markers or associated parameters (urinary 8-oxo-dG, plasma radical absorbance capacity and carbonyl groups, erythrocyte superoxide dismutase and catalase activities) were unchanged. A very significant reduction of Na+/K+-ATPase activity (−66%, p<0.0001), a reduction of erythrocyte membrane fluidity and alteration in erythrocyte fatty acid membrane profile (increase in monounsaturated fatty acids, decrease in EPA and DHA-ω3 with a consequent increase in ω6/ω3 ratio) were found in Au compared to TD, without change in membrane sialic acid content. Some Au clinical features appear to be correlated with these findings; in particular, hyperactivity score appears to be related with some parameters of the lipidomic profile and membrane fluidity. Oxidative stress and erythrocyte membrane alterations may play a role in the pathogenesis of ASD and prompt the development of palliative therapeutic protocols. Moreover, the marked decrease in NKA could be potentially utilized as a peripheral biomarker of ASD. PMID:23840462

A Virtual Reality avatar interaction (VRai) platform to assess residual executive dysfunction in active military personnel with previous mild traumatic brain injury: proof of concept.

PubMed

Robitaille, Nicolas; Jackson, Philip L; Hébert, Luc J; Mercier, Catherine; Bouyer, Laurent J; Fecteau, Shirley; Richards, Carol L; McFadyen, Bradford J

2017-10-01

This proof of concept study tested the ability of a dual task walking protocol using a recently developed avatar-based virtual reality (VR) platform to detect differences between military personnel post mild traumatic brain injury (mTBI) and healthy controls. The VR platform coordinated motion capture, an interaction and rendering system, and a projection system to present first (participant-controlled) and third person avatars within the context of a specific military patrol scene. A divided attention task was also added. A healthy control group was compared to a group with previous mTBI (both groups comprised of six military personnel) and a repeated measures ANOVA tested for differences between conditions and groups based on recognition errors, walking speed and fluidity and obstacle clearance. The VR platform was well tolerated by both groups. Walking fluidity was degraded for the control group within the more complex navigational dual tasking involving avatars, and appeared greatest in the dual tasking with the interacting avatar. This navigational behaviour was not seen in the mTBI group. The present findings show proof of concept for using avatars, particularly more interactive avatars, to expose differences in executive functioning when applying context-specific protocols (here for the military). Implications for rehabilitation Virtual reality provides a means to control context-specific factors for assessment and intervention. Adding human interaction and agency through avatars increases the ecologic nature of the virtual environment. Avatars in the present application of the Virtual Reality avatar interaction platform appear to provide a better ability to reveal differences between trained, military personal with and without mTBI.

Dietary n-6:n-3 ratio and Vitamin E improve motility characteristics in association with membrane properties of boar spermatozoa.

PubMed

Liu, Qing; Zhou, Yuan-Fei; Duan, Run-Jia; Wei, Hong-Kui; Peng, Jian; Jiang, Si-Wen

2017-01-01

This study was aimed to evaluate the effects of dietary n-6:n-3 ratio and Vitamin E on the membrane properties and motility characteristics of spermatozoa in boars. Forty Duroc boars were randomly distributed in a 2 × 2 factorial design with two n-6:n-3 ratios (14.4 and 6.6) and two Vitamin E levels (200 and 400 mg kg-1 ). During 16 weeks of treatment, fresh semen was collected at weeks 0, 8, 12, and 16 for measurements of motility characteristics, contents of fatty acids, membrane properties (membrane fluidity and membrane integrity), and lipid peroxidation of the spermatozoa. The semen was diluted in Beltsville Thawing Solution (BTS) extender and stored at 17°C, and the sperm motility was assessed at 12, 36, 72, and 120 h of storage. The 6.6 n-6:n-3 dietary ratio increased the contents of n-3 polyunsaturated fatty acids (PUFAs) and docosahexaenoic acid (DHA) and improved the membrane integrity and membrane fluidity of the spermatozoa, resulting in notably increased total motility, sperm progressive motility, and velocity parameters of fresh semen. Feeding diet with Vitamin E (400 mg kg-1 ) prevented sperm lipid peroxidation, and resulted in higher total motility and sperm progressive motility in fresh and liquid stored semen. In conclusion, the adjustment of n-6:n-3 ratio (6.6) and supply of Vitamin E (400 mg kg-1 ) successfully improved sperm motility characteristics and thus may be beneficial to the fertility of boars, which might be due to the modification of the physical and functional properties of spermatozoa membrane in response to dietary supplementation.

Changes in membrane biophysical properties induced by the Budesonide/Hydroxypropyl-β-cyclodextrin complex.

PubMed

Dos Santos, Andreia G; Bayiha, Jules César; Dufour, Gilles; Cataldo, Didier; Evrard, Brigitte; Silva, Liana C; Deleu, Magali; Mingeot-Leclercq, Marie-Paule

2017-10-01

Budesonide (BUD), a poorly soluble anti-inflammatory drug, is used to treat patients suffering from asthma and COPD (Chronic Obstructive Pulmonary Disease). Hydroxypropyl-β-cyclodextrin (HPβCD), a biocompatible cyclodextrin known to interact with cholesterol, is used as a drug-solubilizing agent in pharmaceutical formulations. Budesonide administered as an inclusion complex within HPβCD (BUD:HPβCD) required a quarter of the nominal dose of the suspension formulation and significantly reduced neutrophil-induced inflammation in a COPD mouse model exceeding the effect of each molecule administered individually. This suggests the role of lipid domains enriched in cholesterol for inflammatory signaling activation. In this context, we investigated the effect of BUD:HPβCD on the biophysical properties of membrane lipids. On cellular models (A549, lung epithelial cells), BUD:HPβCD extracted cholesterol similarly to HPβCD. On large unilamellar vesicles (LUVs), by using the fluorescent probes diphenylhexatriene (DPH) and calcein, we demonstrated an increase in membrane fluidity and permeability induced by BUD:HPβCD in vesicles containing cholesterol. On giant unilamellar vesicles (GUVs) and lipid monolayers, BUD:HPβCD induced the disruption of cholesterol-enriched raft-like liquid ordered domains as well as changes in lipid packing and lipid desorption from the cholesterol monolayers, respectively. Except for membrane fluidity, all these effects were enhanced when HPβCD was complexed with budesonide as compared with HPβCD. Since cholesterol-enriched domains have been linked to membrane signaling including pathways involved in inflammation processes, we hypothesized the effects of BUD:HPβCD could be partly mediated by changes in the biophysical properties of cholesterol-enriched domains. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of the Tissue and Stromal Cell Components of Micro-Superficial Enhanced Fluid Fat Injection (Micro-SEFFI) for Facial Aging Treatment.

PubMed

Rossi, Martina; Roda, Barbara; Zia, Silvia; Vigliotta, Ilaria; Zannini, Chiara; Alviano, Francesco; Bonsi, Laura; Zattoni, Andrea; Reschiglian, Pierluigi; Gennai, Alessandro

2018-06-14

New microfat preparations provide material suitable for use as a regenerative filler for different facial areas. To support the development of new robust techniques for regenerative purposes, the cellular content of the sample should be considered. To evaluate the stromal vascular fraction (SVF) cell components of micro-superficial enhanced fluid fat injection (SEFFI) samples via a technique to harvest re-injectable tissue with minimum manipulation. The results were compared to those obtained from SEFFI samples. Microscopy analysis was performed to visualize the tissue structure. Micro-SEFFI samples were also fractionated using Celector ®, an innovative non-invasive separation technique, to provide an initial evaluation of sample fluidity and composition. SVFs obtained from SEFFI and micro-SEFFI were studied. Adipose stromal cells (ASCs) were isolated and characterized by proliferation and differentiation capacity assays. Microscopic and quality analyses of micro-SEFFI samples by Celector® confirmed the high fluidity and sample cellular composition in terms of red blood cell contamination, the presence of cell aggregates and extracellular matrix fragments. ASCs were isolated from adipose tissue harvested using SEFFI and micro-SEFFI systems. These cells were demonstrated to have a good proliferation rate and differentiation potential towards mesenchymal lineages. Despite the small sizes and low cellularity observed in micro-SEFFI-derived tissue, we were able to isolate stem cells. This result partially explains the regenerative potential of autologous micro-SEFFI tissue grafts. In addition, using this novel Celector® technology, tissues used for aging treatment were characterized analytically, and the adipose tissue composition was evaluated with no need for extra sample processing.

Temperature-dependent changes in the swimming behaviour of Tetrahymena pyriformis-NT1 and their interrelationships with electrophysiology and the state of membrane lipids.

PubMed

Connolly, J G; Brown, I D; Lee, A G; Kerkut, G A

1985-01-01

The swimming velocity and the amplitude of the helical swimming path of T. pyriformis-NT1 cells grown at 20 degrees C (Tg 20 degrees C) and 38 degrees C (Tg 38 degrees C) were monitored between 0 and 40 degrees C in the presence and absence of electric fields. Within physiological limits the swimming velocity increased and the amplitude decreased as temperature was raised. The temperature profiles of these properties were not linear, and showed discontinuities at different temperatures for the different cultures. The break points in Arrhenius plots of the resting potential, regenerative spike magnitude, repolarization time, swimming velocity and swimming amplitude are tabulated and compared. The initial breakpoints upon cooling were clustered about the breakpoints in fluorescence polarization of D.P.H. in extracted phospholipids, and around the transition temperatures estimated from the literature for the pellicular membrane of these cells. The average of the initial breakpoints on cooling was 22.9 degrees C for Tg 38 degrees C cells and 13.7 degrees C for Tg 20 degrees C cells, a shift of 9.2 degrees C. Unlike Paramecium there is no depolarizing receptor potential in Tetrahymena upon warming. It is suggested that this may be the basis of a behavioural difference between Tetrahymena and Paramecium--namely that in Tetrahymena maximum swimming velocity occurs above growth temperature whereas in Paramecium the two points coincide. Swimming velocity and resting potential were correlated with membrane fluidity within physiological limits, but for other parameters the relationship with fluidity was more complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Stearoyl-CoA desaturase is an essential enzyme for the parasitic protist Trypanosoma brucei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alloatti, Andres; Gupta, Shreedhara; Gualdron-Lopez, Melisa

2011-08-26

Highlights: {yields} Inhibiting {Delta}9 desaturase drastically changes T. brucei's fatty-acid composition. {yields} Isoxyl specifically inhibits the {Delta}9 desaturase causing a growth arrest. {yields} RNA interference of desaturase expression causes a similar effect. {yields} Feeding T. brucei-infected mice with Isoxyl decreases the parasitemia. {yields} 70% of Isoxyl-treated mice survived the trypanosome infection. -- Abstract: Trypanosoma brucei, the etiologic agent of sleeping sickness, is exposed to important changes in nutrients and temperature during its life cycle. To adapt to these changes, the fluidity of its membranes plays a crucial role. This fluidity, mediated by the fatty-acid composition, is regulated by enzymes namedmore » desaturases. We have previously shown that the oleoyl desaturase is essential for Trypanosoma cruzi and T. brucei. In this work, we present experimental support for the relevance of stearoyl-CoA desaturase (SCD) for T. brucei's survival, in both its insect or procyclic-form (PCF) and bloodstream-form (BSF) stages. We evaluated this essentiality in two different ways: by generating a SCD knocked-down parasite line using RNA interference, and by chemical inhibition of the enzyme with two compounds, Isoxyl and a thiastearate with the sulfur atom at position 10 (10-TS). The effective concentration for 50% growth inhibition (EC{sub 50}) of PCF was 1.0 {+-} 0.2 {mu}M for Isoxyl and 5 {+-} 2 {mu}M for 10-TS, whereas BSF appeared more susceptible with EC{sub 50} values 0.10 {+-} 0.03 {mu}M (Isoxyl) and 1.0 {+-} 0.6 {mu}M (10-TS). RNA interference showed to be deleterious for both stages of the parasite. In addition, T. brucei-infected mice were fed with Isoxyl, causing a reduction of the parasitemia and an increase of the rodents' survival.« less

Heat stress dictates microbial lipid composition in hydrothermal marine sediments

NASA Astrophysics Data System (ADS)

Sollich, M.; Yoshinaga, M. Y.; Häusler, S.; Hinrichs, K. U.; Bühring, S. I.

2016-02-01

Abundant and diverse microbial communities inhabit hydrothermal marine sediments. Since ion permeability of membranes increases with temperature archaea and bacteria that use proton/sodium as coupling ions for bioenergetics must constantly adjust their cytoplasmic membrane permeability, which in turn is mostly controlled by the lipid composition. Here, we investigated a thermal gradient across a marine sediment field (ranging from 18 to over 100°C) and tested the concept that membrane lipids provide a major biochemical basis for cellular bioenergetics of archaea and bacteria under stressful conditions. Reflecting the lower ion permeability of the ether-linked isoprenoidal lipids, we found that archaea dominate over bacteria in sediments of >50 °C. Moreover, a detailed examination of the molecular lipid species revealed a quandary: low membrane permeability concomitantly with increased fluidity is required for energy conservation of both archaea and bacteria under heat stress. For instance, bacterial fatty acids were found to increase chain length in concert with a higher degree of unsaturation at elevated sediment temperatures while archaeal tetraethers were observed to show a higher degree of bulking (e.g. methylation and H-shaped) and fluidity (i.e. cyclization) under elevated temperatures. In addition, our data indicate that strong intermolecular hydrogen bonding at the headgroup level of archaeal glycolipids and bacterial sphingolipids may provide ideal membrane stability to attain the required balance between low permeability and a more fluidized configuration. For example, sphingolipids may stabilize bacterial phospholipids into lipid domains, enabling bacteria to thrive in heated sediments under unfavorable thermodynamic conditions. The scientific marriage of lipidomics and bioenergetics described here provides a new dimension for understanding microbial life in natural environments.

Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers

PubMed Central

Harding, Tommy; Roger, Andrew J.; Simpson, Alastair G. B.

2017-01-01

The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa. To gather fundamental knowledge about salt adaptation in these organisms, we studied the transcriptome-level response of Halocafeteria seosinensis (Stramenopiles) grown under contrasting salinities. We provided further evolutionary context to our analysis by identifying genes that underwent recent duplications. Genes that were highly responsive to salinity variations were involved in stress response (e.g., chaperones), ion homeostasis (e.g., Na+/H+ transporter), metabolism and transport of lipids (e.g., sterol biosynthetic genes), carbohydrate metabolism (e.g., glycosidases), and signal transduction pathways (e.g., transcription factors). A significantly high proportion (43%) of duplicated genes were also differentially expressed, accentuating the importance of gene expansion in adaptation by H. seosinensis to high salt environments. Furthermore, we found two genes that were lateral acquisitions from bacteria, and were also highly up-regulated and highly expressed at high salt, suggesting that this evolutionary mechanism could also have facilitated adaptation to high salt. We propose that a transition toward high-salt adaptation in the ancestors of H. seosinensis required the acquisition of new genes via duplication, and some lateral gene transfers (LGTs), as well as the alteration of transcriptional programs, leading to increased stress resistance, proper establishment of ion gradients, and modification of cell structure properties like membrane fluidity. PMID:28611746

[Lidocaine-containing hyaluronic acid filler on a CPM® basis for lip augmentation : Experience from clinical practice].

PubMed

Fischer, T; Sattler, G; Gauglitz, G

2016-06-01

Lip augmentation with hyaluronic acid fillers is an established procedure. As monophasic polydensified hyaluronic acid products with variable density CPM-HAL1 (Belotero® Balance Lidocaine) and CPM-HAL2 (Belotero® Intense Lidocaine) are qualified for beautification and particularly natural-looking rejuvenation, respectively. Assessment of handling and outcome of lip augmentation using the lidocaine-containing hyaluronic acid fillers CPM-HAL1 and CPM-HAL2. Data from patients who received lip augmentation by means of bautification and/or rejuvenation using CPM-HAL1 and/or CPM-HAL2 were documented. Observation period was 4 months, with assessment of natural outcome, evenness, handling, fluidity, distribution, malleability, tolerability, as well as patient satisfaction and pain. In total, 146 patients from 21 German centres participated. Physicians rated natural outcome and evenness as good or very good for > 95 % of patients. Handling, fluidity, distribution and malleability were assessed for both fillers as good or very good in > 91 % of patients. At every evaluation point, more than 93 % of patients were very or very much satisfied with the product. A total of 125 patients (85.6 %) experienced transient injection-related side effects. Pain intensity during the procedure was mild (2.72 ± 1.72 on the 0-10 pain assessment scale) and abated markedly within 30 min (0.42 ± 0.57). Lip augmentation with hyaluronic acid fillers produced a long-term cosmetic result. Due to the lidocaine content, procedural pain was low and transient. Accordingly, a high degree of patient satisfaction was achieved that was maintained throughout the observation period.

How tall buildings affect turbulent air flows and dispersion of pollution within a neighbourhood.

PubMed

Aristodemou, Elsa; Boganegra, Luz Maria; Mottet, Laetitia; Pavlidis, Dimitrios; Constantinou, Achilleas; Pain, Christopher; Robins, Alan; ApSimon, Helen

2018-02-01

The city of London, UK, has seen in recent years an increase in the number of high-rise/multi-storey buildings ("skyscrapers") with roof heights reaching 150 m and more, with the Shard being a prime example with a height of ∼310 m. This changing cityscape together with recent plans of local authorities of introducing Combined Heat and Power Plant (CHP) led to a detailed study in which CFD and wind tunnel studies were carried out to assess the effect of such high-rise buildings on the dispersion of air pollution in their vicinity. A new, open-source simulator, FLUIDITY, which incorporates the Large Eddy Simulation (LES) method, was implemented; the simulated results were subsequently validated against experimental measurements from the EnFlo wind tunnel. The novelty of the LES methodology within FLUIDITY is based on the combination of an adaptive, unstructured, mesh with an eddy-viscosity tensor (for the sub-grid scales) that is anisotropic. The simulated normalised mean concentrations results were compared to the corresponding wind tunnel measurements, showing for most detector locations good correlations, with differences ranging from 3% to 37%. The validation procedure was followed by the simulation of two further hypothetical scenarios, in which the heights of buildings surrounding the source building were increased. The results showed clearly how the high-rise buildings affected the surrounding air flows and dispersion patterns, with the generation of "dead-zones" and high-concentration "hotspots" in areas where these did not previously exist. The work clearly showed that complex CFD modelling can provide useful information to urban planners when changes to cityscapes are considered, so that design options can be tested against environmental quality criteria. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Dietary n-6:n-3 ratio and Vitamin E improve motility characteristics in association with membrane properties of boar spermatozoa

PubMed Central

Liu, Qing; Zhou, Yuan-Fei; Duan, Run-Jia; Wei, Hong-Kui; Peng, Jian; Jiang, Si-Wen

2017-01-01

This study was aimed to evaluate the effects of dietary n-6:n-3 ratio and Vitamin E on the membrane properties and motility characteristics of spermatozoa in boars. Forty Duroc boars were randomly distributed in a 2 × 2 factorial design with two n-6:n-3 ratios (14.4 and 6.6) and two Vitamin E levels (200 and 400 mg kg−1). During 16 weeks of treatment, fresh semen was collected at weeks 0, 8, 12, and 16 for measurements of motility characteristics, contents of fatty acids, membrane properties (membrane fluidity and membrane integrity), and lipid peroxidation of the spermatozoa. The semen was diluted in Beltsville Thawing Solution (BTS) extender and stored at 17°C, and the sperm motility was assessed at 12, 36, 72, and 120 h of storage. The 6.6 n-6:n-3 dietary ratio increased the contents of n-3 polyunsaturated fatty acids (PUFAs) and docosahexaenoic acid (DHA) and improved the membrane integrity and membrane fluidity of the spermatozoa, resulting in notably increased total motility, sperm progressive motility, and velocity parameters of fresh semen. Feeding diet with Vitamin E (400 mg kg−1) prevented sperm lipid peroxidation, and resulted in higher total motility and sperm progressive motility in fresh and liquid stored semen. In conclusion, the adjustment of n-6:n-3 ratio (6.6) and supply of Vitamin E (400 mg kg−1) successfully improved sperm motility characteristics and thus may be beneficial to the fertility of boars, which might be due to the modification of the physical and functional properties of spermatozoa membrane in response to dietary supplementation. PMID:26763547

Fermentation Temperature Modulates Phosphatidylethanolamine and Phosphatidylinositol Levels in the Cell Membrane of Saccharomyces cerevisiae

PubMed Central

Henderson, Clark M.; Zeno, Wade F.; Lerno, Larry A.; Longo, Marjorie L.

2013-01-01

During alcoholic fermentation, Saccharomyces cerevisiae is exposed to a host of environmental and physiological stresses. Extremes of fermentation temperature have previously been demonstrated to induce fermentation arrest under growth conditions that would otherwise result in complete sugar utilization at “normal” temperatures and nutrient levels. Fermentations were carried out at 15°C, 25°C, and 35°C in a defined high-sugar medium using three Saccharomyces cerevisiae strains with diverse fermentation characteristics. The lipid composition of these strains was analyzed at two fermentation stages, when ethanol levels were low early in stationary phase and in late stationary phase at high ethanol concentrations. Several lipids exhibited dramatic differences in membrane concentration in a temperature-dependent manner. Principal component analysis (PCA) was used as a tool to elucidate correlations between specific lipid species and fermentation temperature for each yeast strain. Fermentations carried out at 35°C exhibited very high concentrations of several phosphatidylinositol species, whereas at 15°C these yeast strains exhibited higher levels of phosphatidylethanolamine and phosphatidylcholine species with medium-chain fatty acids. Furthermore, membrane concentrations of ergosterol were highest in the yeast strain that experienced stuck fermentations at all three temperatures. Fluorescence anisotropy measurements of yeast cell membrane fluidity during fermentation were carried out using the lipophilic fluorophore diphenylhexatriene. These measurements demonstrate that the changes in the lipid composition of these yeast strains across the range of fermentation temperatures used in this study did not significantly affect cell membrane fluidity. However, the results from this study indicate that fermenting S. cerevisiae modulates its membrane lipid composition in a temperature-dependent manner. PMID:23811519

Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution

PubMed Central

Zhou, Aifen; Baidoo, Edward; He, Zhili; Mukhopadhyay, Aindrila; Baumohl, Jason K; Benke, Peter; Joachimiak, Marcin P; Xie, Ming; Song, Rong; Arkin, Adam P; Hazen, Terry C; Keasling, Jay D; Wall, Judy D; Stahl, David A; Zhou, Jizhong

2013-01-01

Desulfovibrio vulgaris Hildenborough strains with significantly increased tolerance to NaCl were obtained via experimental evolution. A NaCl-evolved strain, ES9-11, isolated from a population cultured for 1200 generations in medium amended with 100 mM NaCl, showed better tolerance to NaCl than a control strain, EC3-10, cultured for 1200 generations in parallel but without NaCl amendment in medium. To understand the NaCl adaptation mechanism in ES9-11, we analyzed the transcriptional, metabolite and phospholipid fatty acid (PLFA) profiles of strain ES9-11 with 0, 100- or 250 mM-added NaCl in medium compared with the ancestral strain and EC3-10 as controls. In all the culture conditions, increased expressions of genes involved in amino-acid synthesis and transport, energy production, cation efflux and decreased expression of flagellar assembly genes were detected in ES9-11. Consistently, increased abundances of organic solutes and decreased cell motility were observed in ES9-11. Glutamate appears to be the most important osmoprotectant in D. vulgaris under NaCl stress, whereas, other organic solutes such as glutamine, glycine and glycine betaine might contribute to NaCl tolerance under low NaCl concentration only. Unsaturation indices of PLFA significantly increased in ES9-11. Branched unsaturated PLFAs i17:1 ω9c, a17:1 ω9c and branched saturated i15:0 might have important roles in maintaining proper membrane fluidity under NaCl stress. Taken together, these data suggest that the accumulation of osmolytes, increased membrane fluidity, decreased cell motility and possibly an increased exclusion of Na+ contribute to increased NaCl tolerance in NaCl-evolved D. vulgaris. PMID:23575373

Connexin Type and Fluorescent Protein Fusion Tag Determine Structural Stability of Gap Junction Plaques.

PubMed

Stout, Randy F; Snapp, Erik Lee; Spray, David C

2015-09-25

Gap junctions (GJs) are made up of plaques of laterally clustered intercellular channels and the membranes in which the channels are embedded. Arrangement of channels within a plaque determines subcellular distribution of connexin binding partners and sites of intercellular signaling. Here, we report the discovery that some connexin types form plaque structures with strikingly different degrees of fluidity in the arrangement of the GJ channel subcomponents of the GJ plaque. We uncovered this property of GJs by applying fluorescence recovery after photobleaching to GJs formed from connexins fused with fluorescent protein tags. We found that connexin 26 (Cx26) and Cx30 GJs readily diffuse within the plaque structures, whereas Cx43 GJs remain persistently immobile for more than 2 min after bleaching. The cytoplasmic C terminus of Cx43 was required for stability of Cx43 plaque arrangement. We provide evidence that these qualitative differences in GJ arrangement stability reflect endogenous characteristics, with the caveat that the sizes of the GJs examined were necessarily large for these measurements. We also uncovered an unrecognized effect of non-monomerized fluorescent protein on the dynamically arranged GJs and the organization of plaques composed of multiple connexin types. Together, these findings redefine our understanding of the GJ plaque structure and should be considered in future studies using fluorescent protein tags to probe dynamics of highly ordered protein complexes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Application of P.O and R-SAC mortar for 3D printing in construction

NASA Astrophysics Data System (ADS)

Lin, J. C.; Wu, X.; Yang, W.; Zhao, R. X.; Qiao, L. G.

2018-01-01

Compared with traditional properties of building materials, 3D printing materials should have controllable setting time, appropriate workability and superior mechanical properties. Adaptability of two types of cementitious system on the 3D printing were investigated in this paper. Results showed that both of them can match of 3D printing process with the working window time required (10-90min) by using the compound adjustable solidification agents, which have the high mechanical properties (3d⩾30MPa, 28d> 63MPa), and appropriate suitable parameter range of fluidity (R-SAC:210-240mm,P.O:200-220mm).

Mechanical Performance Test of Rubber-Powder Modified Concrete

NASA Astrophysics Data System (ADS)

Zhang, Yan Cong; Gao, Ling Ling

2018-06-01

A number of rubber cement concrete specimens that rubber powder dosage different were obtained using same cement, water and fine aggregates, by adjusting the dosage of rubber powder. Then it was used to research the influence of rubber powder dosage on performance of cement concrete by measuring its liquidity, strength and toughness. The results show that: when water-cement ratio was equal and rubber powder replacing the same volume sand, the fluidity of cement concrete almost linear increased with rubber powder dosage increasing. With dosage of rubber powder increasing, compressive strength and flexural strength reduced, but toughness linear growth trend when dosage of rubber powder less 30%.

Advances in liquid metals for biomedical applications.

PubMed

Yan, Junjie; Lu, Yue; Chen, Guojun; Yang, Min; Gu, Zhen

2018-04-23

To date, liquid metals have been widely applied in many fields such as electronics, mechanical engineering and energy. In the last decade, with a better understanding of the physicochemical properties such as low viscosity, good fluidity, high thermal/electrical conductivity and good biocompatibility, gallium and gallium-based low-melting-point (near or below physiological temperature) alloys have attracted considerable attention in bio-related applications. This tutorial review introduces the common performances of liquid metals, highlights their featured properties, as well as summarizes various state-of-the-art bio-applications involving carriers for drug delivery, molecular imaging, cancer therapy and biomedical devices. Challenges for the clinical translation of liquid metals are also discussed.

Hemorheological abnormalities in human arterial hypertension

NASA Astrophysics Data System (ADS)

Lo Presti, Rosalia; Hopps, Eugenia; Caimi, Gregorio

2014-05-01

Blood rheology is impaired in hypertensive patients. The alteration involves blood and plasma viscosity, and the erythrocyte behaviour is often abnormal. The hemorheological pattern appears to be related to some pathophysiological mechanisms of hypertension and to organ damage, in particular left ventricular hypertrophy and myocardial ischemia. Abnormalities have been observed in erythrocyte membrane fluidity, explored by fluorescence spectroscopy and electron spin resonance. This may be relevant for red cell flow in microvessels and oxygen delivery to tissues. Although blood viscosity is not a direct target of antihypertensive therapy, the rheological properties of blood play a role in the pathophysiology of arterial hypertension and its vascular complications.

Viscous optical clearing agent for in vivo optical imaging

NASA Astrophysics Data System (ADS)

Deng, Zijian; Jing, Lijia; Wu, Ning; lv, Pengyu; Jiang, Xiaoyun; Ren, Qiushi; Li, Changhui

2014-07-01

By allowing more photons to reach deeper tissue, the optical clearing agent (OCA) has gained increasing attention in various optical imaging modalities. However, commonly used OCAs have high fluidity, limiting their applications in in vivo studies with oblique, uneven, or moving surfaces. In this work, we reported an OCA with high viscosity. We measured the properties of this viscous OCA, and tested its successful performances in the imaging of a living animal's skin with two optical imaging modalities: photoacoustic microscopy and optical coherence tomography. Our results demonstrated that the viscous OCA has a great potential in the study of different turbid tissues using various optical imaging modalities.

"Freezing" of nanoconfined fluids under an electric field.

PubMed

Xie, Guoxin; Luo, Jianbin; Liu, Shuhai; Guo, Dan; Zhang, Chenhui

2010-02-02

The problem of the solidlike transition of fluids in a nanogap has drawn much fundamental and practical attention. Here, we directly observed the disappearance of the fluidity of liquids confined within a gap with a surface separation of >10 nm under an EF in a ball-plate system, which is called the "freezing" of liquids. The flow of the nanoconfined liquid became very weak as the EF intensity was increased to a critical value and was correlated with the liquid polarity and the film thickness. It is deduced that the EF can induce more liquid molecules to be aligned to form more ordered layers in the nanogap.

Embracing the "and": between queer and bisexual theory at Brighton BiFest.

PubMed

Voss, Georgina; Browne, Kath; Gupta, Camel

2014-01-01

Questions of bi identities can be invisibilized and overlooked by queer theorizing and LGBT studies. This article explores the ways in which complex performances of bisexuality can simultaneously encompass and deconstructively critique bi identity in a manner that embraces the "and" between bi and queer, offering important insights into how bi is lived, contested, and reaffirmed. Drawing on the BiCon and BiFest events in the UK, we argue that both the materialities (and supposed fixities) of bi erasures and exclusions and the fluidities that trouble the heterosexual/homosexual divides offer key insights into the spatial and temporal fixing and unfixing of identities.

Physicochemical properties of binary solutions of propylene carbonate-acetonitrile in the range of 253.15-313.15 K

NASA Astrophysics Data System (ADS)

Tyunina, E. Yu.; Chekunova, M. D.

2017-05-01

The density, dynamic viscosity, and dielectric constant of propylene carbonate solutions with acetonitrile are measured over the composition of a mixed solvent at temperatures of 253.15, 273.15, 293.15, and 313.15 K. The molar volume, molar viscosity, and molar capacity of a mixture of propylene carbonate-acetonitrile and an excess amount of it are calculated. The effect the temperature and composition of the mixture have on the excess molar properties is discussed. A linear correlation is observed between the values of the molar fluidity, capacity, polarization, and molar volume of the studied system.

Dietary fatty acids and membrane protein function.

PubMed

Murphy, M G

1990-02-01

In recent years, there has been growing public awareness of the potential health benefits of dietary fatty acids, and of the distinction between the effects of the omega6 and omega3 polyunsaturated fatty acids that are concentrated in vegetable and fish oils, respectively. A part of the biologic effectiveness of the two families of polyunsaturated fatty acids resides in their relative roles as precursors of the eicosanoids. However, we are also beginning to appreciate that as the major components of the hydrophobic core of the membrane bilayer, they can interact with and directly influence the functioning of select integral membrane proteins. Among the most important of these are the enzymes, receptors, and ion channels that are situated in the plasma membrane of the cell, since they carry out the communication and homeostatic processes that are necessary for normal cell function. This review examines current information regarding the effects of diet-induced changes in plasma membrane fatty acid composition on several specific enzymes (adenylate cyclase, 5'-nucleotidase, Na(+)/K(+)-ATPase) and cell-surface receptors (opiate, adrenergic, insulin). Dietary manipulation studies have demonstrated a sensitivity of each to a fatty acid environment that is variably dependent on the nature of the fatty acid(s) and/or source of the membrane. The molecular mechanisms appear to involve fatty acid-dependent effects on protein conformation, on the "fluidity" and/or thickness of the membrane, or on protein synthesis. Together, the results of these studies reinforce the concept that dietary fats have the potential to regulate physiologic function and to further our understanding of how this occurs at a membrane level.

Can membrane-bound carotenoid pigment zeaxanthin carry out a transmembrane proton transfer?

PubMed

Kupisz, Kamila; Sujak, Agnieszka; Patyra, Magdalena; Trebacz, Kazimierz; Gruszecki, Wiesław I

2008-10-01

Polar carotenoid pigment zeaxanthin (beta,beta-carotene-3,3'-diol) incorporated into planar lipid membranes formed with diphytanoyl phosphatidylcholine increases the specific electric resistance of the membrane from ca. 4 to 13 x 10(7) Omega cm2 (at 5 mol% zeaxanthin with respect to lipid). Such an observation is consistent with the well known effect of polar carotenoids in decreasing fluidity and structural stabilization of lipid bilayers. Zeaxanthin incorporated into the lipid membrane at 1 mol% has very small effect on the overall membrane resistance but facilitates equilibration of the transmembrane proton gradient, as demonstrated with the application of the H+-sensitive antimony electrodes. Relatively low changes in the electrical potential suggest that the equilibration process may be associated with a symport/antiport activity or with a transmembrane transfer of the molecules of acid. UV-Vis linear dichroism analysis of multibilayer formed with the same lipid-carotenoid system shows that the transition dipole moment of the pigment molecules forms a mean angle of 21 degrees with respect to the axis normal to the plane of the membrane. This means that zeaxanthin spans the membrane and tends to have its two hydroxyl groups anchored in the opposite polar zones of the membrane. Detailed FTIR analysis of beta-carotene and zeaxanthin indicates that the polyene chain of carotenoids is able to form weak hydrogen bonds with water molecules. Possible molecular mechanisms responsible for proton transport by polyenes are discussed, including direct involvement of the polyene chain in proton transfer and indirect effect of the pigment on physical properties of the membrane.

The role of alcohol in forging and maintaining friendships amongst Scottish men in midlife.

PubMed

Emslie, Carol; Hunt, Kate; Lyons, Antonia

2013-01-01

Men drink more heavily and are more likely to die from alcohol-related causes than women. Most alcohol research focuses on young drinkers. We describe the context of men's drinking in midlife and explore how alcohol is associated with the construction of masculinities. Qualitative research was used to examine the social context of drinking alcohol. We conducted 15 focus groups (single and mixed sex) with respondents in the west of Scotland, United Kingdom. Here we focus on the findings from 22 men aged 28 to 52 years. Men regarded drinking pints of beer in the pub together as an "act of friendship" and this functioned as a hegemonically appropriate way to communicate with and support each other. However, male friends also constructed some nonhegemonic behaviors as forgivable-and indeed acceptable-while drinking alcohol together. This included practices such as the explicit discussion of emotions and mental health and the consumption of "feminine" drinks under certain circumstances (e.g., in private, with close friends). This exploration of drinking reveals the fluidity of gender constructions-and the strategic ways in which men take up positions around hegemonic masculinity-in midlife. The close interweaving of drinking pints in the pub with notions of male friendship could lead to both health-damaging (excessive drinking) and potentially health-promoting (social support) behaviors. Health promotion experts need to be sensitive to cultural constructions of gender to address the high rates of drinking in this age group. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Wax-tear and meibum protein, wax–β-carotene interactions in vitro using infrared spectroscopy

PubMed Central

Faheem, Samad; Kim, Sung-Hye; Nguyen, Jonathan; Neravetla, Shantanu; Ball, Matthew; Foulks, Gary N; Yappert, Marta C; Borchman, Douglas

2012-01-01

Protein–meibum and terpenoids–meibum lipid interactions could be important in the etiology of meibomian gland dysfunction (MGD) and dry eye symptoms. In the current model studies, attenuated total reflectance (ATR) infrared (IR) spectroscopy was used to determine if the terpenoid β-carotene and the major proteins in tears and meibum affect the hydrocarbon chain conformation and carbonyl environment of wax, an abundant component of meibum. The main finding of these studies is that mucin binding to wax disordered slightly the conformation of the hydrocarbon chains of wax and caused the wax carbonyls to become hydrogen bonded or experience a more hydrophilic environment. Lysozyme and lactoglobulin, two proteins shown to bind to monolayers of meibum, did not have such an effect. Keratin and β-carotene did not affect the fluidity (viscosity) or environment of the carbonyl moieties of wax. Based on these results, tetraterpenoids are not likely to influence the structure of meibum in the meibomian glands. In addition, these findings suggest that it is unlikely that keratin blocks meibomian glands by causing the meibum to become more viscous. Among the tear fluid proteins studied, mucin is the most likely to influence the conformation and carbonyl environment of meibum at the tear film surface. PMID:22564968

Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

PubMed

Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

2012-10-15

Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, characterization, and evaluation of ionizable lysine-based lipids for siRNA delivery.

PubMed

Walsh, Colin L; Nguyen, Juliane; Tiffany, Matthew R; Szoka, Francis C

2013-01-16

We report the synthesis and characterization of a series of ionizable lysine-based lipids (ILL), novel lipids containing a lysine headgroup linked to a long-chain dialkylamine through an amide linkage at the lysine α-amine. These ILLs contain two ionizable amines and a carboxylate, and exhibit pH-dependent lipid ionization that varies with lipid structure. The synthetic scheme employed allows for the simple, orthogonal manipulation of lipids. This provides a method for the development of a compositionally diverse library with varying ionizable headgroups, tail structures, and linker regions. A focused library of four ILLs was synthesized to determine the impact of hydrophobic fluidity, lipid net charge, and lipid pK(a) on the biophysical and siRNA transfection characteristics of this new class of lipids. We found that manipulation of lipid structure impacts the protonation behavior, electrostatically driven membrane disruption, and ability to promote siRNA mediated knockdown in vitro. ILL-siRNA liposomal formulations were tested in a murine Factor VII model; however, no significant siRNA-mediated knockdown was observed. These results indicate that ILL may be useful in vitro transfection reagents, but further optimization of this new class of lipids is required to develop an effective in vivo siRNA delivery system.

Minoxidil Skin Delivery from Nanoemulsion Formulations Containing Eucalyptol or Oleic Acid: Enhanced Diffusivity and Follicular Targeting

PubMed Central

Abd, Eman; Benson, Heather A. E.; Roberts, Michael S.; Grice, Jeffrey E.

2018-01-01

In this work, we examined enhanced skin delivery of minoxidil applied in nanoemulsions incorporating skin penetration enhancers. Aliquots of fully characterized oil-in-water nanoemulsions (1 mL), containing minoxidil (2%) and the skin penetration enhancer oleic acid or eucalyptol as oil phases, were applied to full-thickness excised human skin in Franz diffusion cells, while aqueous solutions (1 mL) containing minoxidil were used as controls. Minoxidil in the stratum corneum (SC), hair follicles, deeper skin layers, and flux through the skin over 24 h was determined, as well as minoxidil solubility in the formulations and in the SC. The nanoemulsions significantly enhanced the permeation of minoxidil through skin compared with control solutions. The eucalyptol formulations (NE) promoted minoxidil retention in the SC and deeper skin layers more than did the oleic acid formulations, while the oleic acid formulations (NO) gave the greatest hair follicle penetration. Minoxidil maximum flux enhancement was associated with increases in both minoxidil SC solubility and skin diffusivity in both nanoemulsion systems. The mechanism of enhancement appeared to be driven largely by increased diffusivity, rather than increased partitioning into the stratum corneum, supporting the concept of enhanced fluidity and disruption of stratum corneum lipids. PMID:29370122

Antioxidant and membrane effects of procyanidin dimers and trimers isolated from peanut and cocoa.

PubMed

Verstraeten, Sandra V; Hammerstone, John F; Keen, Carl L; Fraga, César G; Oteiza, Patricia I

2005-06-15

The antioxidant and membrane effects of dimer (Dim) and trimer (Trim) procyanidins isolated from cocoa (Theobroma cacao) (B- and C-bonded) and peanut (Arachis hypogea L.) skin (A-bonded) were evaluated in phosphatidyl choline liposomes. When liposomes were oxidized with a steady source of oxidants, the above dimers and trimers inhibited to a similar extent lipid oxidation in a concentration (0.33-5 microM)-dependent manner. With respect to membrane effects, Dim A1, Dim B, Trim A, and Trim C increased (Dim A1 = Dim B and Trim A = Trim C), while Dim A2 decreased, membrane surface potential. All of the procyanidins tested decreased membrane fluidity as determined by fluorescent probes at the water-lipid interface, an effect that extended into the hydrophobic region of the bilayer. Both dimers and trimers protected the lipid bilayer from disruption by Triton X-100. The magnitude of the protection was Dim A1 > Dim A2 > Dim B and Trim C > Trim A. Thus, dimers and trimers can interact with membrane phospholipids, presumably with their polar headgroup. As a consequence of this interaction, they can provide protection against the attack of oxidants and other molecules that challenge the integrity of the bilayer.

Abnormal passive chloride absorption in cystic fibrosis jejunum functionally opposes the classic chloride secretory defect

PubMed Central

Russo, Michael A.; Högenauer, Christoph; Coates, Stephen W.; Santa Ana, Carol A.; Porter, Jack L.; Rosenblatt, Randall L.; Emmett, Michael; Fordtran, John S.

2003-01-01

Due to genetic defects in apical membrane chloride channels, the cystic fibrosis (CF) intestine does not secrete chloride normally. Depressed chloride secretion leaves CF intestinal absorptive processes unopposed, which results in net fluid hyperabsorption, dehydration of intestinal contents, and a propensity to inspissated intestinal obstruction. This theory is based primarily on in vitro studies of jejunal mucosa. To determine if CF patients actually hyperabsorb fluid in vivo, we measured electrolyte and water absorption during steady-state perfusion of the jejunum. As expected, chloride secretion was abnormally low in CF, but surprisingly, there was no net hyperabsorption of sodium or water during perfusion of a balanced electrolyte solution. This suggested that fluid absorption processes are reduced in CF jejunum, and further studies revealed that this was due to a marked depression of passive chloride absorption. Although Na+-glucose cotransport was normal in the CF jejunum, absence of passive chloride absorption completely blocked glucose-stimulated net sodium absorption and reduced glucose-stimulated water absorption 66%. This chloride absorptive abnormality acts in physiological opposition to the classic chloride secretory defect in the CF intestine. By increasing the fluidity of intraluminal contents, absence of passive chloride absorption may reduce the incidence and severity of intestinal disease in patients with CF. PMID:12840066

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDermaid, Christopher M., E-mail: chris.macdermaid@temple.edu; Klein, Michael L.; Fiorin, Giacomo, E-mail: giacomo.fiorin@temple.edu

The architecture of a biological membrane hinges upon the fundamental fact that its properties are determined by more than the sum of its individual components. Studies on model membranes have shown the need to characterize in molecular detail how properties such as thickness, fluidity, and macroscopic bending rigidity are regulated by the interactions between individual molecules in a non-trivial fashion. Simulation-based approaches are invaluable to this purpose but are typically limited to short sampling times and model systems that are often smaller than the required properties. To alleviate both limitations, the use of coarse-grained (CG) models is nowadays an establishedmore » computational strategy. We here present a new CG force field for cholesterol, which was developed by using measured properties of small molecules, and can be used in combination with our previously developed force field for phospholipids. The new model performs with precision comparable to atomistic force fields in predicting the properties of cholesterol-rich phospholipid bilayers, including area per lipid, bilayer thickness, tail order parameter, increase in bending rigidity, and propensity to form liquid-ordered domains in ternary mixtures. We suggest the use of this model to quantify the impact of cholesterol on macroscopic properties and on microscopic phenomena involving localization and trafficking of lipids and proteins on cellular membranes.« less

Thermal cracking of poly α-olefin aviation lubricating base oil

NASA Astrophysics Data System (ADS)

Fei, Yiwei; Wu, Nan; Ma, Jun; Hao, Jingtuan

2018-02-01

Thermal cracking of poly α-olefin (PAO) was conducted under different temperatures among 190 °C to 300 °C. The reacted mixtures were sequentially detected by gas chromatography-mass spectrometer (GC/MS). A series of small molecular normal alkanes, branched alkanes and olefins were identified. PAO perfect structure of aligned comb-likely side-chains has been seriously cracked under high temperatures. Property changes about kinematic viscosity and pour point of PAO samples reacted under high temperatures were also investigated. The appearance of small molecular compounds weakened the thermal stability, viscosity temperature performance and low temperature fluidity of PAO samples. Property of PAO samples was deteriorated due to thermal cracking under high temperatures.

Manganese oxide electrochemical capacitor with potassium poly(acrylate) hydrogel electrolyte

NASA Astrophysics Data System (ADS)

Lee, Kuang-Tsin; Wu, Nae-Lih

An aqueous gel electrolyte has for the first time been successfully applied to the MnO 2· nH 2O-based pseudocapacitive electrochemical capacitors (ECs). The gel electrolyte is made of potassium poly(acrylate) (PAAK) polymer and aqueous solution of KCl. With the selected composition, PAAK:KCl:H 2O = 9.0%:6.7%:84.3% by weight, the gel shows no fluidity, possessing an ionic conductivity in the order of 10 -1 S cm -1. The gel electrolyte has been found to give substantially higher specific capacitances than those in the liquid electrolyte with the same salt (KCl) composition (1 M) and high power capability (>10 kW/kg).

Lexical shifts, substantive changes, and continuity in State of the Union discourse, 1790–2014

PubMed Central

Rule, Alix; Cointet, Jean-Philippe; Bearman, Peter S.

2015-01-01

This study reveals that the entry into World War I in 1917 indexed the decisive transition to the modern period in American political consciousness, ushering in new objects of political discourse, a more rapid pace of change of those objects, and a fundamental reframing of the main tasks of governance. We develop a strategy for identifying meaningful categories in textual corpora that span long historic durées, where terms, concepts, and language use changes. Our approach is able to account for the fluidity of discursive categories over time, and to analyze their continuity by identifying the discursive stream as the object of interest. PMID:26261302

Darwin's foil: the evolving uses of William Paley's Natural Theology 1802-2005.

PubMed

Shapiro, Adam R

2014-03-01

This essay traces the divergent readings of William Paley's 1802 Natural Theology from its initial publication to the recent controversies over intelligent design. It argues that the misinterpretation of the Natural Theology as a scientific argument about the origins of complex life-which Darwin's Origin of Species refutes-did not develop all at once. Rather this reading evolved gradually, drawing from a variety of uses and appropriations during the course of the nineteenth and twentieth centuries. This study demonstrates the fluidity of "science" and "religion" during these centuries, and highlights the role that genres of science popularization play in altering the meaning of those categories. Copyright © 2013 Elsevier Ltd. All rights reserved.

Movers and Stayers: Novel Assemblages in Changing Environments.

PubMed

Hobbs, Richard J; Valentine, Leonie E; Standish, Rachel J; Jackson, Stephen T

2018-02-01

Increased attention to species movement in response to environmental change highlights the need to consider changes in species distributions and altered biological assemblages. Such changes are well known from paleoecological studies, but have accelerated with ongoing pervasive human influence. In addition to species that move, some species will stay put, leading to an array of novel interactions. Species show a variety of responses that can allow movement or persistence. Conservation and restoration actions have traditionally focused on maintaining or returning species in particular places, but increasingly also include interventions that facilitate movement. Approaches are required that incorporate the fluidity of biotic assemblages into the goals set and interventions deployed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of bio-sourced binder to metal injection moulding

NASA Astrophysics Data System (ADS)

Royer, Alexandre; Barrière, Thierry; Gelin, Jean-Claude

2016-10-01

In the MIM process the binder play the most important role. It provides fluidity of the feedstock mixture for injection molding and adhesion of the powder to keep the molded shape. The binder must provide strength and cohesion for the molded part, must be easy to be removed from the molded part, and must be the recyclable, environmentally friendly and economical ones. The goal of this study is to develop a binder environmentally friendly. For this, a study of formulation based on polyethylene glycol, because of is water debinding properties, was made. Polylactic acid and Polyhydroxyalkanoates were investigated as bio sourced polymers. The chemical, miscibility and rheological behavior of the binder formulation were investigated.

High-efficiency water-loaded microwave antenna in ultra-high-frequency band

NASA Astrophysics Data System (ADS)

Gong, Zilun; Bartone, Chris; Yang, Fuyi; Yao, Jie

2018-03-01

High-index dielectrics are widely used in microwave antennas to control the radiation characteristics. Liquid water, with a high dielectric index at microwave frequency, is an interesting material to achieving tunable functionalities. Here, we demonstrate a water-loaded microwave antenna system that has high loss-tolerance and wideband tunability enabled by fluidity. Our simulation and experimental results show that the resonance frequency can be effectively tuned by the size of loading water. Furthermore, the antenna systems with water loading can achieve high radiation efficiency (>90%) in the ultra-high-frequency (0.3-3 GHz) band. This work brings about opportunities in realistic tunable microwave antenna designs enabled by liquid.

Construction of viscosity diagrams for CaO-SiO2-Al2O3-8% MgO-4% B2O3 slags by the simplex lattice method

NASA Astrophysics Data System (ADS)

Babenko, A. A.; Istomin, S. A.; Zhuchkov, V. I.; Sychev, A. V.; Ryabov, V. V.; Upolovnikova, A. G.

2017-05-01

The simplex lattice method of planning experiments is used to study the viscosities of CaO-SiO2-Al2O3-8% MgO-4% B2O3 slags in a wide chemical composition range. For each viscosity, we developed an adequate mathematical model in the form of a reduced third-order polynomial. The results of mathematical simulation are presented in composition-viscosity diagrams. Composition regions with a high fluidity of slags, the viscosities of which are 0.8-1.2 Pa s in the temperature range 1500-1600°C, are indicated in the diagrams.

Coder’s Manual: A Guide to TEPIAC Documentation.

DTIC Science & Technology

1977-07-01

Po Polonium Am Americium Hg Mercury Pr Praseodymium *Ar Argon (Hydrargyrum) Pt Platinum (also A) Ho Holmium Pu Plutonium *As Arsenic *1 Iodine Ra...Er 20 3 208 D ChD2 110 F F 2 Fe (FeF 21 209 E C 6H1 5ErO1 2S 3[Er(C 2 HSO 4)3] III G GaO4P [GaPO4] 210 F CH3 F 112 H 1iNO 212 G C8 H20Ge [Ge(C 2 H 5...Fluidity, 69 Heat conductance (contact), 62 Fluidized bed, 27 Heat conduction, 57 Fluorescence, 125 Heat conductivity, 57 Food products, 31 Heat content

Lipids as universal biomarkers of extraterrestrial life.

PubMed

Georgiou, Christos D; Deamer, David W

2014-06-01

In 1965, James Lovelock published a general statement, based on thermodynamic chemical equilibrium principles, about how to detect extant or extinct life on a planet other than Earth. Nearly 50 years later, it is possible to make such measurements with robotic missions such as current and future Mars rovers, and probes to sample icy plumes of Enceladus or Europa. We make a specific recommendation that certain characteristic patterns in the composition of lipid hydrocarbons can only result from a biological process, because the signal arises from a universal requirement related to lipid bilayer fluidity and membrane stability. Furthermore, the pattern can be preserved over millions of years, and instrumentation is already available to be incorporated into flight missions.

The influence of fine aggregates on the 3D printing performance

NASA Astrophysics Data System (ADS)

Lin, J. C.; Wu, X.; Yang, W.; Zhao, R. X.; Qiao, L. G.

2018-01-01

Influences of nature Particle, size, grain shape and fineness modulus of fine aggregates on the 3D printing performance of cement-based mortar were investigated. Results showed that the working performance of the mortar is not only dependent on the fineness of the aggregate, but also the gradation and grain size of the aggregate. And the mechanical properties of the mortar are increasing with the increase of Mx in the same test condition. The research shows that it is effective to choose different properties of materials for different design requirements, and the fluidity of mortar must be decreased under assuring construction quality and the pumpability of 3D printing materials.

Mechanical Properties and Microstructure of Class C Fly Ash-Based Geopolymer Paste and Mortar.

PubMed

Li, Xueying; Ma, Xinwei; Zhang, Shoujie; Zheng, Enzu

2013-04-09

This paper presents workability, compressive strength and microstructure for geopolymer pastes and mortars made of class C fly ash at mass ratios of water-to-fly ash from 0.30 to 0.35. Fluidity was in the range of 145-173 mm for pastes and 131-136 mm for mortars. The highest strengths of paste and mortar were 58 MPa and 85 MPa when they were cured at 70 °C for 24 h. In XRD patterns, unreacted quartz and some reacted product were observed. SEM examination indicated that reacted product has formed and covered the unreacted particles in the paste and mortar that were consistent with their high strength.

Improved In Vitro and In Vivo Biocompatibility of Graphene Oxide through Surface Modification: Poly(Acrylic Acid)-Functionalization is Superior to PEGylation.

PubMed

Xu, Ming; Zhu, Jianqiang; Wang, Fanfan; Xiong, Yunjing; Wu, Yakun; Wang, Qiuquan; Weng, Jian; Zhang, Zhihong; Chen, Wei; Liu, Sijin

2016-03-22

The unique physicochemical properties of two-dimensional (2D) graphene oxide (GO) could greatly benefit the biomedical field; however, recent research demonstrated that GO could induce in vitro and in vivo toxicity. We determined the mechanism of GO induced toxicity, and our in vitro experiments revealed that pristine GO could impair cell membrane integrity and functions including regulation of membrane- and cytoskeleton-associated genes, membrane permeability, fluidity and ion channels. Furthermore, GO induced platelet depletion, pro-inflammatory response and pathological changes of lung and liver in mice. To improve the biocompatibility of pristine GO, we prepared a series of GO derivatives including aminated GO (GO-NH2), poly(acrylamide)-functionalized GO (GO-PAM), poly(acrylic acid)-functionalized GO (GO-PAA) and poly(ethylene glycol)-functionalized GO (GO-PEG), and compared their toxicity with pristine GO in vitro and in vivo. Among these GO derivatives, GO-PEG and GO-PAA induced less toxicity than pristine GO, and GO-PAA was the most biocompatible one in vitro and in vivo. The differences in biocompatibility were due to the differential compositions of protein corona, especially immunoglobulin G (IgG), formed on their surfaces that determine their cell membrane interaction and cellular uptake, the extent of platelet depletion in blood, thrombus formation under short-term exposure and the pro-inflammatory effects under long-term exposure. Overall, our combined data delineated the key molecular mechanisms underlying the in vivo and in vitro biological behaviors and toxicity of pristine GO, and identified a safer GO derivative that could be used for future applications.

Seasonal acclimatization of brain lipidome in a eurythermal fish (Carassius carassius) is mainly determined by temperature.

PubMed

Käkelä, Reijo; Mattila, Minja; Hermansson, Martin; Haimi, Perttu; Uphoff, Andreas; Paajanen, Vesa; Somerharju, Pentti; Vornanen, Matti

2008-05-01

Crucian carp (Carassius carassius) is an excellent vertebrate model for studies on temperature adaptation in biological excitable membranes, since the species can tolerate temperatures from 0 to +36 degrees C. To determine how temperature affects the lipid composition of brain, the fish were acclimated for 4 wk at +30, +16, or +4 degrees C in the laboratory, or seasonally acclimatized individuals were captured from the wild throughout the year (temperature = +1 to +23 degrees C), and the brain glycerophospholipid and sphingolipid compositions were analyzed in detail by electrospray-ionization mass spectrometry. Numerous significant temperature-related changes were found in the molecular species composition of the membrane lipids. The most notable and novel finding was a large (approximately 3-fold) increase of the di-22:6n-3 phosphatidylserine and phosphatidylethanolamine species in the cold. Since the increase of 22:6n-3 in the total fatty acyl pool of the brain was small, the formation of di-22:6n-3 aminophospholipid species appears to be a specific adaptation to low temperature. Such highly unsaturated species could be needed to maintain adequate membrane fluidity in the vicinity of transporters and other integral membrane proteins. Plasmalogens increased somewhat at higher temperatures, possibly to protect membranes against oxidation. The modifications of brain lipidome during the 4-wk laboratory acclimation were, in many respects, similar to those found in the wild, which indicates that the seasonal changes observed in the wild are temperature dependent rather than induced by other environmental factors.

Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban.

PubMed

Wasser, Samuel K; Mailand, Celia; Booth, Rebecca; Mutayoba, Benezeth; Kisamo, Emily; Clark, Bill; Stephens, Matthew

2007-03-06

The illegal ivory trade recently intensified to the highest levels ever reported. Policing this trafficking has been hampered by the inability to reliably determine geographic origin of contraband ivory. Ivory can be smuggled across multiple international borders and along numerous trade routes, making poaching hotspots and potential trade routes difficult to identify. This fluidity also makes it difficult to refute a country's denial of poaching problems. We extend an innovative DNA assignment method to determine the geographic origin(s) of large elephant ivory seizures. A Voronoi tessellation method is used that utilizes genetic similarities across tusks to simultaneously infer the origin of multiple samples that could have one or more common origin(s). We show that this joint analysis performs better than sample-by-sample methods in assigning sample clusters of known origin. The joint method is then used to infer the geographic origin of the largest ivory seizure since the 1989 ivory trade ban. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that the ivory was entirely from savanna elephants, most probably originating from a narrow east-to-west band of southern Africa, centered on Zambia. These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory. Broader applications to wildlife trade are discussed.

Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban

PubMed Central

Wasser, Samuel K.; Mailand, Celia; Booth, Rebecca; Mutayoba, Benezeth; Kisamo, Emily; Clark, Bill; Stephens, Matthew

2007-01-01

The illegal ivory trade recently intensified to the highest levels ever reported. Policing this trafficking has been hampered by the inability to reliably determine geographic origin of contraband ivory. Ivory can be smuggled across multiple international borders and along numerous trade routes, making poaching hotspots and potential trade routes difficult to identify. This fluidity also makes it difficult to refute a country's denial of poaching problems. We extend an innovative DNA assignment method to determine the geographic origin(s) of large elephant ivory seizures. A Voronoi tessellation method is used that utilizes genetic similarities across tusks to simultaneously infer the origin of multiple samples that could have one or more common origin(s). We show that this joint analysis performs better than sample-by-sample methods in assigning sample clusters of known origin. The joint method is then used to infer the geographic origin of the largest ivory seizure since the 1989 ivory trade ban. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that the ivory was entirely from savanna elephants, most probably originating from a narrow east-to-west band of southern Africa, centered on Zambia. These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory. Broader applications to wildlife trade are discussed. PMID:17360505

Dynamic Lipid-dependent Modulation of Protein Topology by Post-translational Phosphorylation.

PubMed

Vitrac, Heidi; MacLean, David M; Karlstaedt, Anja; Taegtmeyer, Heinrich; Jayaraman, Vasanthi; Bogdanov, Mikhail; Dowhan, William

2017-02-03

Membrane protein topology and folding are governed by structural principles and topogenic signals that are recognized and decoded by the protein insertion and translocation machineries at the time of initial membrane insertion and folding. We previously demonstrated that the lipid environment is also a determinant of initial protein topology, which is dynamically responsive to post-assembly changes in membrane lipid composition. However, the effect on protein topology of post-assembly phosphorylation of amino acids localized within initially cytoplasmically oriented extramembrane domains has never been investigated. Here, we show in a controlled in vitro system that phosphorylation of a membrane protein can trigger a change in topological arrangement. The rate of change occurred on a scale of seconds, comparable with the rates observed upon changes in the protein lipid environment. The rate and extent of topological rearrangement were dependent on the charges of extramembrane domains and the lipid bilayer surface. Using model membranes mimicking the lipid compositions of eukaryotic organelles, we determined that anionic lipids, cholesterol, sphingomyelin, and membrane fluidity play critical roles in these processes. Our results demonstrate how post-translational modifications may influence membrane protein topology in a lipid-dependent manner, both along the organelle trafficking pathway and at their final destination. The results provide further evidence that membrane protein topology is dynamic, integrating for the first time the effect of changes in lipid composition and regulators of cellular processes. The discovery of a new topology regulatory mechanism opens additional avenues for understanding unexplored structure-function relationships and the development of optimized topology prediction tools. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Pulmonary lung surfactant synthetic peptide concentration-dependent modulation of DPPC and POPG acyl chain order in a DPPC:POPG:palmitic acid lipid mixture.

PubMed

Krill, S L; Gupta, S L; Smith, T

1994-05-06

Lung surfactant-associated protein interaction with lipid matrices and the effects on lipid thermotropic phase behavior are areas of active research. Many studies limit the lipids to a single or two-component system. The current investigation utilizes a three-lipid component matrix (DPPC:POPG:palmitic acid) to investigate the impact of a synthetic surfactant protein B fragment (SP-B 53-78 DiACM) on the dynamic surface activity of the lipid admixture as measured by a Wilhelmy surface balance. Also, the modulation of the individual lipid acyl chain order by the peptide within the lipid matrix is studied through the use of thermal perturbation FTIR spectroscopy. The data clearly demonstrate a concentration-dependent effect of the peptide on the surface activity with an improvement in the dynamic surface tension diagram characteristics (decreased surface tension and increased collapse plateau) especially at low, 0.36 M%, peptide concentrations. These effects are diminished upon further addition of the peptide. FTIR spectral data demonstrate that the peptide addition results in a significant increase in the acyl chain order of the DPPC and POPG components as measured by the position of the methylene stretching vibrational bands. DPPC is most sensitive to the peptide presence, while the palmitic acid is least affected. The transition temperatures of the individual lipids are also increased with the addition of the peptide. The presence of POPG in the matrix achieves the surface activity similarly seen with natural lung surfactant relative to a DPPC/palmitic acid lipid matrix alone. Its presence increases the sensitivity of the DPPC acyl chains to the presence of the peptide. These effects on the chain order are most probably related to the increased acyl chain fluidity which POPG imparts to the lipid matrix because of the presence of the cis double bond. The phosphatidylglycerol headgroup also adds a negative charge to the lipid matrix which enhances the peptide-lipid interaction. Although the palmitic acid is minimally affected by the peptide, its presence, as suggested by surface balance measurements, results in the establishment of a stable lipid film with DPPC, capable of achieving low surface tension values.

Numerical Modelling of Tsunami Generated by Deformable Submarine Slides: Parameterisation of Slide Dynamics for Coupling to Tsunami Propagation Model

NASA Astrophysics Data System (ADS)

Smith, R. C.; Collins, G. S.; Hill, J.; Piggott, M. D.; Mouradian, S. L.

2015-12-01

Numerical modelling informs risk assessment of tsunami generated by submarine slides; however, for large-scale slides modelling can be complex and computationally challenging. Many previous numerical studies have approximated slides as rigid blocks that moved according to prescribed motion. However, wave characteristics are strongly dependent on the motion of the slide and previous work has recommended that more accurate representation of slide dynamics is needed. We have used the finite-element, adaptive-mesh CFD model Fluidity, to perform multi-material simulations of deformable submarine slide-generated waves at real world scales for a 2D scenario in the Gulf of Mexico. Our high-resolution approach represents slide dynamics with good accuracy, compared to other numerical simulations of this scenario, but precludes tracking of wave propagation over large distances. To enable efficient modelling of further propagation of the waves, we investigate an approach to extract information about the slide evolution from our multi-material simulations in order to drive a single-layer wave propagation model, also using Fluidity, which is much less computationally expensive. The extracted submarine slide geometry and position as a function of time are parameterised using simple polynomial functions. The polynomial functions are used to inform a prescribed velocity boundary condition in a single-layer simulation, mimicking the effect the submarine slide motion has on the water column. The approach is verified by successful comparison of wave generation in the single-layer model with that recorded in the multi-material, multi-layer simulations. We then extend this approach to 3D for further validation of this methodology (using the Gulf of Mexico scenario proposed by Horrillo et al., 2013) and to consider the effect of lateral spreading. This methodology is then used to simulate a series of hypothetical submarine slide events in the Arctic Ocean (based on evidence of historic slides) and examine the hazard posed to the UK coast.

IFITM Proteins Restrict Viral Membrane Hemifusion

PubMed Central

Golfetto, Ottavia; Bungart, Brittani; Li, Minghua; Ding, Shilei; He, Yuxian; Liang, Chen; Lee, James C.; Gratton, Enrico; Cohen, Fredric S.; Liu, Shan-Lu

2013-01-01

The interferon-inducible transmembrane (IFITM) protein family represents a new class of cellular restriction factors that block early stages of viral replication; the underlying mechanism is currently not known. Here we provide evidence that IFITM proteins restrict membrane fusion induced by representatives of all three classes of viral membrane fusion proteins. IFITM1 profoundly suppressed syncytia formation and cell-cell fusion induced by almost all viral fusion proteins examined; IFITM2 and IFITM3 also strongly inhibited their fusion, with efficiency somewhat dependent on cell types. Furthermore, treatment of cells with IFN also markedly inhibited viral membrane fusion and entry. By using the Jaagsiekte sheep retrovirus envelope and influenza A virus hemagglutinin as models for study, we showed that IFITM-mediated restriction on membrane fusion is not at the steps of receptor- and/or low pH-mediated triggering; instead, the creation of hemifusion was essentially blocked by IFITMs. Chlorpromazine (CPZ), a chemical known to promote the transition from hemifusion to full fusion, was unable to rescue the IFITM-mediated restriction on fusion. In contrast, oleic acid (OA), a lipid analog that generates negative spontaneous curvature and thereby promotes hemifusion, virtually overcame the restriction. To explore the possible effect of IFITM proteins on membrane molecular order and fluidity, we performed fluorescence labeling with Laurdan, in conjunction with two-photon laser scanning and fluorescence-lifetime imaging microscopy (FLIM). We observed that the generalized polarizations (GPs) and fluorescence lifetimes of cell membranes expressing IFITM proteins were greatly enhanced, indicating higher molecularly ordered and less fluidized membranes. Collectively, our data demonstrated that IFITM proteins suppress viral membrane fusion before the creation of hemifusion, and suggested that they may do so by reducing membrane fluidity and conferring a positive spontaneous curvature in the outer leaflets of cell membranes. Our study provides novel insight into the understanding of how IFITM protein family restricts viral membrane fusion and infection. PMID:23358889

Renegotiating intimate relationships with men: how HIV shapes attitudes and experiences of marriage for South African women living with HIV: 'Now in my life, everything I do, looking at my health'

PubMed

Cooper, Diane; Moore, Elena; Mantell, Joanne E

2013-01-01

This paper explores marriage attitudes and practices among Xhosa-speaking women living with HIV (WLHIV) in Cape Town, South Africa. It reports on a study that assessed the fertility intentions of a cohort of people living with HIV, aimed at informing an HIV care intervention. It draws on qualitative data generated from 30 successive interviews with WHLIV in wave 1, 23 interviews in wave 2 and 20 follow-up interviews in wave 3. Gender inequality, marriage and HIV are strongly intertwined. Broader layers of South Africa's history, politics and socio-economic and cultural contexts have consequences for the fluidity in intimate relations, marriage and motherhood for WLHIV. Key and conflicting themes emerge that impact on marriage and motherhood. Firstly, marriage is the 'last on a list of priorities' for WLHIV, who wish to further their children's education, to work, to earn money, and to achieve this rapidly because of their HIV-positive status. We demonstrate that the pressure women face in marriage to bear children creates a different attitude to and experience of marriage for WLHIV. Some WLHIV wish to avoid marriage due to its accompanying pressure to have children. Other WLHIV experience difficulties securing intimacy. WLHIV may find it easier to seek partners who are also living with HIV. A partner living with HIV is perceived as sharing similar fertility goals. In this study, HIV accentuates existing issues and highlights new ones for WLHIV negotiating intimacy. The findings contribute to the existing knowledge base regarding the fluidity of marriage and fertility intentions within the dynamic context of living with HIV. These are likely to have broader relevance in currently rapidly urbanising and economically developing countries with high HIV prevalence in southern Africa.

Modulating membrane fluidity corrects Batten disease phenotypes in vitro and in vivo.

PubMed

Schultz, Mark L; Tecedor, Luis; Lysenko, Elena; Ramachandran, Shyam; Stein, Colleen S; Davidson, Beverly L

2018-07-01

The neuronal ceroid lipofuscinoses are a class of inherited neurodegenerative diseases characterized by the accumulation of autofluorescent storage material. The most common neuronal ceroid lipofuscinosis has juvenile onset with rapid onset blindness and progressive degeneration of cognitive processes. The juvenile form is caused by mutations in the CLN3 gene, which encodes the protein CLN3. While mouse models of Cln3 deficiency show mild disease phenotypes, it is apparent from patient tissue- and cell-based studies that its loss impacts many cellular processes. Using Cln3 deficient mice, we previously described defects in mouse brain endothelial cells and blood-brain barrier (BBB) permeability. Here we expand on this to other components of the BBB and show that Cln3 deficient mice have increased astrocyte endfeet area. Interestingly, this phenotype is corrected by treatment with a commonly used GAP junction inhibitor, carbenoxolone (CBX). In addition to its action on GAP junctions, CBX has also been proposed to alter lipid microdomains. In this work, we show that CBX modifies lipid microdomains and corrects membrane fluidity alterations in Cln3 deficient endothelial cells, which in turn improves defects in endocytosis, caveolin-1 distribution at the plasma membrane, and Cdc42 activity. In further work using the NIH Library of Integrated Network-based Cellular Signatures (LINCS), we discovered other small molecules whose impact was similar to CBX in that they improved Cln3-deficient cell phenotypes. Moreover, Cln3 deficient mice treated orally with CBX exhibited recovery of impaired BBB responses and reduced autofluorescence. CBX and the compounds identified by LINCS, many of which have been used in humans or approved for other indications, may find therapeutic benefit in children suffering from CLN3 deficiency through mechanisms independent of their original intended use. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Structural study of the effects of mutations in proteins to identify the molecular basis of the loss of local structural fluidity leading to the onset of autoimmune diseases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Ananya; Ghosh, Semanti; Bagchi, Angshuman

Protein-Protein Interactions (PPIs) are crucial in most of the biological processes and PPI dysfunctions are known to be associated with the onsets of various diseases. One of such diseases is the auto-immune disease. Auto-immune diseases are one among the less studied group of diseases with very high mortality rates. Thus, we tried to correlate the appearances of mutations with their probable biochemical basis of the molecular mechanisms leading to the onset of the disease phenotypes. We compared the effects of the Single Amino Acid Variants (SAVs) in the wild type and mutated proteins to identify any structural deformities that mightmore » lead to altered PPIs leading ultimately to disease onset. For this we used Relative Solvent Accessibility (RSA) as a spatial parameter to compare the structural perturbation in mutated and wild type proteins. We observed that the mutations were capable to increase intra-chain PPIs whereas inter-chain PPIs would remain mostly unaltered. This might lead to more intra-molecular friction causing a deleterious alteration of protein's normal function. A Lyapunov exponent analysis, using the altered RSA values due to polymorphic and disease causing mutations, revealed polymorphic mutations have a positive mean value for the Lyapunov exponent while disease causing mutations have a negative mean value. Thus, local spatial stochasticity has been lost due to disease causing mutations, indicating a loss of structural fluidity. The amino acid conversion plot also showed a clear tendency of altered surface patch residue conversion propensity than polymorphic conversions. So far, this is the first report that compares the effects of different kinds of mutations (disease and non-disease causing polymorphic mutations) in the onset of autoimmune diseases. - Highlights: • Protein-Protein Interaction. • Changes in Relative Solvent Accessibility (RSA). • Amino acid conversion matrix. • Polymorphic mutations. • Disease causing mutations.« less

Heat Stress Dictates Microbial Lipid Composition along a Thermal Gradient in Marine Sediments

PubMed Central

Sollich, Miriam; Yoshinaga, Marcos Y.; Häusler, Stefan; Price, Roy E.; Hinrichs, Kai-Uwe; Bühring, Solveig I.

2017-01-01

Temperature exerts a first-order control on microbial populations, which constantly adjust the fluidity and permeability of their cell membrane lipids to minimize loss of energy by ion diffusion across the membrane. Analytical advances in liquid chromatography coupled to mass spectrometry have allowed the detection of a stunning diversity of bacterial and archaeal lipids in extreme environments such as hot springs, hydrothermal vents and deep subsurface marine sediments. Here, we investigated a thermal gradient from 18 to 101°C across a marine sediment field and tested the hypothesis that cell membrane lipids provide a major biochemical basis for the bioenergetics of archaea and bacteria under heat stress. This paper features a detailed lipidomics approach with the focus on membrane lipid structure-function. Membrane lipids analyzed here include polar lipids of bacteria and polar and core lipids of archaea. Reflecting the low permeability of their ether-linked isoprenoids, we found that archaeal polar lipids generally dominate over bacterial lipids in deep layers of the sediments influenced by hydrothermal fluids. A close examination of archaeal and bacterial lipids revealed a membrane quandary: not only low permeability, but also increased fluidity of membranes are required as a unified property of microbial membranes for energy conservation under heat stress. For instance, bacterial fatty acids were composed of longer chain lengths in concert with higher degree of unsaturation while archaea modified their tetraethers by incorporation of additional methyl groups at elevated sediment temperatures. It is possible that these configurations toward a more fluidized membrane at elevated temperatures are counterbalanced by the high abundance of archaeal glycolipids and bacterial sphingolipids, which could reduce membrane permeability through strong intermolecular hydrogen bonding. Our results provide a new angle for interpreting membrane lipid structure-function enabling archaea and bacteria to survive and grow in hydrothermal systems. PMID:28878741

Stroke survivors' and informal caregivers' experiences of primary care and community healthcare services - A systematic review and meta-ethnography.

PubMed

Pindus, Dominika M; Mullis, Ricky; Lim, Lisa; Wellwood, Ian; Rundell, A Viona; Abd Aziz, Noor Azah; Mant, Jonathan

2018-01-01

To describe and explain stroke survivors and informal caregivers' experiences of primary care and community healthcare services. To offer potential solutions for how negative experiences could be addressed by healthcare services. Systematic review and meta-ethnography. Medline, CINAHL, Embase and PsycINFO databases (literature searched until May 2015, published studies ranged from 1996 to 2015). Primary qualitative studies focused on adult community-dwelling stroke survivors' and/or informal caregivers' experiences of primary care and/or community healthcare services. A set of common second order constructs (original authors' interpretations of participants' experiences) were identified across the studies and used to develop a novel integrative account of the data (third order constructs). Study quality was assessed using the Critical Appraisal Skills Programme checklist. Relevance was assessed using Dixon-Woods' criteria. 51 studies (including 168 stroke survivors and 328 caregivers) were synthesised. We developed three inter-dependent third order constructs: (1) marginalisation of stroke survivors and caregivers by healthcare services, (2) passivity versus proactivity in the relationship between health services and the patient/caregiver dyad, and (3) fluidity of stroke related needs for both patient and caregiver. Issues of continuity of care, limitations in access to services and inadequate information provision drove perceptions of marginalisation and passivity of services for both patients and caregivers. Fluidity was apparent through changing information needs and psychological adaptation to living with long-term consequences of stroke. Potential limitations of qualitative research such as limited generalisability and inability to provide firm answers are offset by the consistency of the findings across a range of countries and healthcare systems. Stroke survivors and caregivers feel abandoned because they have become marginalised by services and they do not have the knowledge or skills to re-engage. This can be addressed by: (1) increasing stroke specific health literacy by targeted and timely information provision, and (2) improving continuity of care between specialist and generalist services. PROSPERO 2015:CRD42015026602.

Testing an egg yolk supplemented diet on boars to aid in sperm adaptation at 5°C.

PubMed

Casas, Isabel; Miller-Lux, Yvonne; Osborne, Betty; Bonet, Sergi; Althouse, Gary C

2015-01-01

In many species, extended semen can be stored at low temperatures to slow bacterial growth. However, boar semen performs poorly at temperatures below 15 °C and this poses unique challenges, as it is not easy to maintain a constant 15-19 °C during shipment. Some extenders have been formulated with egg yolk for storage at 5 °C but the addition of egg yolk is not applicable in the majority of commercial operations. The purpose of this study was to evaluate if boar dietary supplementation with powdered egg yolk imparts any protective effects on sperm quality when stored at 15 °C and 5 °C for up to 11 days in a conventional extender. Ten boars were fed a commercial diet with the addition of 0.11 Kg of powdered egg yolk for 10 weeks. Ejaculates collected on weeks 4, 6, 8, and 10 were processed for storage at both 15 °C and 5 °C and compared with ejaculates from boars fed a standard diet. Throughout an 11-day storage period, sperm quality was assessed including several motility and morphologic parameters and select plasma membrane properties (fluidity, integrity, and triacylglycerol content). Linear regression models were used to describe effects of treatment, storage day, week and temperature on all sperm parameters. Overall, there were minimal beneficial effects of egg yolk treatment on sperm quality parameters. Sperm from egg yolk supplemented boars did have a slower decline in viability and plasma membrane fluidity than that observed in the control sperm when stored at 5 °C (p < 0.001). Additionally, there was an increase in total morphologic abnormalities in sperm from egg yolk fed boars compared to controls at week 10 (p <  .001). In conclusion, the results of this study do not support a significant benefit to sperm quality or resistance to cold storage when feeding a 10-week dietary supplementation of 0.11 Kg powdered egg yolk to crossbred boars.

Renegotiating intimate relationships with men: how HIV shapes attitudes and experiences of marriage for South African women living with HIV: ‘Now in my life, everything I do, looking at my health’★

PubMed Central

Cooper, Diane; Moore, Elena; Mantell, Joanne E.

2014-01-01

This paper explores marriage attitudes and practices among Xhosa-speaking women living with HIV (WLHIV) in Cape Town, South Africa. It reports on a study that assessed the fertility intentions of a cohort of people living with HIV, aimed at informing an HIV care intervention. It draws on qualitative data generated from 30 successive interviews with WHLIV in wave 1, 23 interviews in wave 2 and 20 follow-up interviews in wave 3. Gender inequality, marriage and HIV are strongly intertwined. Broader layers of South Africa's history, politics and socio-economic and cultural contexts have consequences for the fluidity in intimate relations, marriage and motherhood for WLHIV. Key and conflicting themes emerge that impact on marriage and motherhood. Firstly, marriage is the ‘last on a list of priorities’ for WLHIV, who wish to further their children's education, to work, to earn money, and to achieve this rapidly because of their HIV-positive status. We demonstrate that the pressure women face in marriage to bear children creates a different attitude to and experience of marriage for WLHIV. Some WLHIV wish to avoid marriage due to its accompanying pressure to have children. Other WLHIV experience difficulties securing intimacy. WLHIV may find it easier to seek partners who are also living with HIV. A partner living with HIV is perceived as sharing similar fertility goals. In this study, HIV accentuates existing issues and highlights new ones for WLHIV negotiating intimacy. The findings contribute to the existing knowledge base regarding the fluidity of marriage and fertility intentions within the dynamic context of living with HIV. These are likely to have broader relevance in currently rapidly urbanising and economically developing countries with high HIV prevalence in southern Africa. PMID:25505803

Timing and Mode of Landscape Response to Glacial-Interglacial Climate Forcing From Fluvial Fill Terrace Sediments: Humahuaca Basin, E Cordillera, NW Argentina

NASA Astrophysics Data System (ADS)

Schildgen, T. F.; Robinson, R. A. J.; Savi, S.; Bookhagen, B.; Tofelde, S.; Strecker, M. R.

2014-12-01

Numerical modelling informs risk assessment of tsunami generated by submarine slides; however, for large-scale slides modelling can be complex and computationally challenging. Many previous numerical studies have approximated slides as rigid blocks that moved according to prescribed motion. However, wave characteristics are strongly dependent on the motion of the slide and previous work has recommended that more accurate representation of slide dynamics is needed. We have used the finite-element, adaptive-mesh CFD model Fluidity, to perform multi-material simulations of deformable submarine slide-generated waves at real world scales for a 2D scenario in the Gulf of Mexico. Our high-resolution approach represents slide dynamics with good accuracy, compared to other numerical simulations of this scenario, but precludes tracking of wave propagation over large distances. To enable efficient modelling of further propagation of the waves, we investigate an approach to extract information about the slide evolution from our multi-material simulations in order to drive a single-layer wave propagation model, also using Fluidity, which is much less computationally expensive. The extracted submarine slide geometry and position as a function of time are parameterised using simple polynomial functions. The polynomial functions are used to inform a prescribed velocity boundary condition in a single-layer simulation, mimicking the effect the submarine slide motion has on the water column. The approach is verified by successful comparison of wave generation in the single-layer model with that recorded in the multi-material, multi-layer simulations. We then extend this approach to 3D for further validation of this methodology (using the Gulf of Mexico scenario proposed by Horrillo et al., 2013) and to consider the effect of lateral spreading. This methodology is then used to simulate a series of hypothetical submarine slide events in the Arctic Ocean (based on evidence of historic slides) and examine the hazard posed to the UK coast.

[Lipids, depression and suicide].

PubMed

Colin, A; Reggers, J; Castronovo, V; Ansseau, M

2003-01-01

Polyunsatured fatty acids are made out of a hydrocarbonated chain of variable length with several double bonds. The position of the first double bond (omega) differentiates polyunsatured omega 3 fatty acids (for example: alpha-linolenic acid or alpha-LNA) and polyunsatured omega 6 fatty acids (for example: linoleic acid or LA). These two classes of fatty acids are said to be essential because they cannot be synthetised by the organism and have to be taken from alimentation. The omega 3 are present in linseed oil, nuts, soya beans, wheat and cold water fish whereas omega 6 are present in maize, sunflower and sesame oil. Fatty acids are part of phospholipids and, consequently, of all biological membranes. The membrane fluidity, of crucial importance for its functioning, depends on its lipidic components. Phospholipids composed of chains of polyunsatured fatty acids increase the membrane fluidity because, by bending some chains, double bonds prevent them from compacting themselves perfectly. Membrane fluidity is also determined by the phospholipids/free cholesterol ratio, as cholesterol increases membrane viscosity. A diet based on a high proportion of essential polyunsatured fatty acids (fluid) would allow a higher incorporation of cholesterol (rigid) in the membranes to balance their fluidity, which would contribute to lower blood cholesterol levels. Brain membranes have a very high content in essential polyunsatured fatty acids for which they depend on alimentation. Any dietary lack of essential polyunsatured fatty acids has consequences on cerebral development, modifying the activity of enzymes of the cerebral membranes and decreasing efficiency in learning tasks. The prevalence of depression seems to increase continuously since the beginning of the century. Though different factors most probably contribute to this evolution, it has been suggested that it could be related to an evolution of alimentary patterns in the Western world, in which polyunsatured omega 3 fatty acids contained in fish, game and vegetables have been largely replaced by polyunsatured omega 6 fatty acids of cereal oils. Some epidemiological data support the hypothesis of a relation between lower depression and/or suicide rates and a higher consumption of fish. These data do not however prove a relation of causality. Several cohort studies (on nondepressed subjects) have assessed the relationship between plasma cholesterol and depressive symptoms with contradictory results. Though some results found a significant relationship between a decrease of total cholesterol and high scores of depression, some other did not. Studies among patients suffering from major depression signalled more constantly an association between low cholesterol and major depression. Besides, some trials showed that clinical recovery may be associated with a significant increase of total cholesterol. The hypothesis that a low cholesterol level may represent a suicidal risk factor was discovered accidentally following a series of epidemiological studies which revealed an increase of the suicidal risk among subjects with a low cholesterol level. Though some contradictory studies do exist, this relationship has been confirmed by several subsequent cohort studies. These findings have challenged the vast public health programs aimed at promoting the decrease of cholesterol, and even suggested to suspend the administration of lipid lowering drugs. Recent clinical studies on populations treated with lipid lowering drugs showed nevertheless a lack of significant increase of mortality, either by suicide or accident. In addition, several controlled studies among psychiatric patients revealed a decrease of the concentrations of plasma cholesterol among patients who had attempted suicide in comparison with other patients. In major depression, all studies revealed a significant decrease of the polyunsaturated omega 3 fatty acids and/or an increase of the omega 6/omega 3 ratio in plasma and/or in the membranes of the red cells. In addition, two studies found a higher severity of depression when the level of polyunsaturated omega 3 fatty acids or the ratio omega 3/omega 6 was low. Parallel to these modifications, other biochemical perturbations have been reported in major depression, particularly an activation of the inflammatory response system, resulting in an increase of the pro-inflammatory cytokines (interleukins: IL-1b, IL-6 and interferon g) and eicosanoids (among others, prostaglandin E2) in the blood and the CSF of depressed patients. These substances cause a peroxidation and, consequently a catabolism of membrane phospholipids, among others those containing polyunsaturated fatty acids. The cytokines and eicosanoids derive from polyunsaturated fatty acids and have opposite physiological functions according to their omega 3 or omega 6 precursor. Arachidonic acid (omega 6) is, among others, precursor of pro-inflammatory prostaglandin E2 (PGE2), whereas polyunsaturated omega 3 fatty acids inhibit the formation of PGE2. It has been shown that a dietary increase of polyunsaturated omega 3 fatty acids reduced strongly the production of IL-1 beta, IL-2, IL-6 and TNF-alpha (tumor necrosis factor-alpha). In contrast, diets with a higher supply of linoleic acid (omega 6) increased significantly the production of pro-inflammatory cytokines, like TNF-alpha. Therefore, polyunsaturated omega 3 fatty acids could be associated at different levels in the pathophysiology of major depression, on the one hand through their role in the membrane fluidity which influences diverse steps of neurotransmission and, on the other hand, through their function as precursor of pro-inflammatory cytokines and eicosanoids disturbing neurotransmission. In addition, antidepressants could exhibit an immunoregulating effect by reducing the release of pro-inflammatory cytokines, by increasing the release of endogenous antagonists of pro-inflammatory cytokines like IL-10 and, finally, by acting like inhibitors of cyclo-oxygenase. Data available concerning the administration of supplements of DHA (docosahexanoic acid) or other polyunsaturated fatty acids omega 3 are limited. In a double blind placebo-controlled study on 30 patients with bipolar disorder, the addition of polyunsaturated omega 3 fatty acids was associated with a longer period of remission. Moreover, nearly all the other prognosis measures were better in the omega 3 group. Very recently, a controlled trial showed the benefits of adding an omega 3 fatty acid, eicosopentanoic acid, among depressed patients. After 4 weeks, six of the 10 patients receiving the fatty acid were considered as responders in comparison with only one of the ten patients receiving placebo. Some epidemiological, experimental and clinical data favour the hypothesis that polyunsaturated fatty acids could play a role in the pathogenesis and/or the treatment of depression. More studies however are needed in order to better precise the actual implication of those biochemical factors among the various aspects of depressive illness.

Constructions of masculinity and femininity and sexual risk negotiation practices among women in urban Ghana.

PubMed

Fiaveh, Daniel Y; Izugbara, Chimaraoke O; Okyerefo, Michael P K; Reysoo, Fenneke; Fayorsey, Clara K

2015-01-01

Using qualitative data gathered through in-depth interviews with women in Accra, Ghana, this paper explores narratives of masculinity and femininity and sexual risk negotiation practices among women. While women framed 'proper' masculinity in terms of stereotypical reproductive norms, they also acknowledged the fluidity and multiplicity of masculinities. Femininity was more uniformly characterised in terms of physical attractiveness and beauty, responsibility and reproduction. These features, especially those related to adherence to morally and socially appropriate sexual norms (e.g., menstrual and bodily hygiene, unplanned pregnancy etc.), influenced women's approach to sexual negotiation. Work aiming to support women to negotiate sex safely needs to pay attention to their notions of gender and practices of sexual negotiation.

Retina and Omega-3

PubMed Central

Querques, Giuseppe; Forte, Raimondo; Souied, Eric H.

2011-01-01

Over the last decade, several epidemiological studies based on food frequency questionnaires suggest that omega-3 polyunsaturated fatty acids could have a protective role in reducing the onset and progression of retinal diseases. The retina has a high concentration of omega-3, particularly DHA, which optimizes fluidity of photoreceptor membranes, retinal integrity, and visual function. Furthermore, many studies demonstrated that DHA has a protective, for example antiapoptotic, role in the retina. From a nutritional point of view, it is known that western populations, particularly aged individuals, have a higher than optimal omega-6/omega-3 ratio and should enrich their diet with more fish consumption or have DHA supplementation. This paper underscores the potential beneficial effect of omega-3 fatty acids on retinal diseases. PMID:22175009

Uncertainty and control in the context of a category-five tornado.

PubMed

Afifi, Walid A; Afifi, Tamara D; Merrill, Annie

2014-10-01

The purpose of this qualitative descriptive study was to illuminate the experience and management of uncertainty during a natural disaster. Interviews were conducted with 26 survivors of a category-five tornado that entirely demolished the small, rural town of Greensburg, Kansas. Three primary themes were found in the survivors' accounts. First, the survivors experienced rapidly shifting levels and kinds of uncertainty as they proceeded through the stages of the disaster. Second, the fluidity of much-needed information added to uncertainty. Third, the feeling of lack of control over outcomes of the disaster and its aftermath was pervasive and was often managed through reliance on communal coping. Recommendations for disaster-related intervention programs are suggested. © 2014 Wiley Periodicals, Inc.

Between pink and blue: a multi-dimensional family approach to gender nonconforming children and their families.

PubMed

Malpas, Jean

2011-12-01

Families of gender nonconforming children need to negotiate the interactions between two gender systems: a rigid gender binary imported from familial, social, and cultural experiences and a fluid gender spectrum articulated by their child. This article reviews parental reactions to nonconforming gender developments and poses that the parental mandates of protection and acceptance are problematized by the difference of gender norms between the child and the family, as well as the child and the environment. Through multiple therapeutic modalities-parental coaching and education, parent support group, and child and family therapy-the author illustrates interventions supporting both parents and prepubescent children in their negotiation of safety, connection, and fluidity. Case vignettes illustrate the method in action.

Green hydrophilic interaction chromatography using ethanol-water-carbon dioxide mixtures.

PubMed

Pereira, Alberto dos Santos; Girón, Ana Jiménez; Admasu, Engdawork; Sandra, Pat

2010-03-01

In hydrophilic interaction chromatography (HILIC), best results are obtained with high concentrations of acetonitrile. In the framework of green chromatography, different concentrations of carbon dioxide were added to the mobile phases acetonitrile-water and ethanol-water and the impact on retention and separation in HILIC using bare silica as stationary phase was explored. The features of HILIC using enhanced-fluidity mobile phases are illustrated with the analysis of the nucleobases and a mixture containing the nucleobases and cortisol, flurbiprofen, theophylline and caffeine. For both organic constituents, the elution window is widened in function of the carbon dioxide concentration and selectivity changes. At high concentrations of carbon dioxide in ethanol, separations were similar to those obtained with acetonitrile without carbon dioxide addition.

Expressions of homosexuality and the perspective of analytical psychology.

PubMed

Miller, Barry

2010-02-01

Homosexuality, as a description and category of human experience, has a long, complicated and problematic history. It has been utilized as a carrier of theological, political, and psychological ideologies of all sorts, with varying and contradictory influences into the lives of us all. Analytical psychology, emphasizing the purposiveness found in manifestations of the psyche, offers a unique approach to this subject. The focus moves from causation to the meanings embedded in erotic expressions, fantasies, and dreams. Consequently, homosexuality loses its predetermined meaning and finds its definition in the psychology of the individual. Categories of 'sexual orientation' may defend against personal analysis, deflecting the essential fluidity and mystery of Eros. This is illustrated with samples of the variety found in 'homosexual' material.

Two-photon fluorescence anisotropy imaging

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Yi; Shao, Hanrong; He, Yonghong; Ma, Hui

2006-09-01

We have developed a novel method for imaging the fluorescence intensity and anisotropy by two-photon fluorescence microscopy and tested its capability in biological application. This method is applied to model sample including FITC and FITC-CD44 antibody solution and also FITC-CD44 stained cells. The fluorescence anisotropy (FA) of FITC-CD44ab solution is higher than the FITC solution with the same concentration. The fluorescence in cell sample has even higher FA than in solution because the rotation diffusion is restrained in membrane. The method is employed to study the effect of berberine a kind of Chinese medicine, on tumor metastasis. The results indicated that tumor cell membrane fluidity is decreasing with increasing the concentration of berberine in culture medium.

Mechanical Properties and Microstructure of Class C Fly Ash-Based Geopolymer Paste and Mortar

PubMed Central

Li, Xueying; Ma, Xinwei; Zhang, Shoujie; Zheng, Enzu

2013-01-01

This paper presents workability, compressive strength and microstructure for geopolymer pastes and mortars made of class C fly ash at mass ratios of water-to-fly ash from 0.30 to 0.35. Fluidity was in the range of 145–173 mm for pastes and 131–136 mm for mortars. The highest strengths of paste and mortar were 58 MPa and 85 MPa when they were cured at 70 °C for 24 h. In XRD patterns, unreacted quartz and some reacted product were observed. SEM examination indicated that reacted product has formed and covered the unreacted particles in the paste and mortar that were consistent with their high strength. PMID:28809222

Beneficial effects of ω-3 PUFA in children on cardiovascular risk factors during childhood and adolescence.

PubMed

Bonafini, Sara; Antoniazzi, Franco; Maffeis, Claudio; Minuz, Pietro; Fava, Cristiano

2015-07-01

Omega-3 polyunsatured fatty acids (ω-3 PUFA) are essential nutrients mainly derived from fish and seafood but present also in vegetables such as nuts and seed-oils. Some epidemiological and clinical studies indicate a protection of ω-3 FA against cardiovascular disease and a favourable effect on cardiovascular risk factors control in adults. The evidences of their effects in children and adolescents are scanty but a possible beneficial role, especially for insulin sensitivity and blood pressure control, has been proposed. In this review we want to focus especially on the evidences, which could justify the assumption of ω-3 in children and adolescents, and to underline the aspects which need further investigation. Mechanisms through which ω-3 FA act are manifolds and still a matter of investigation: beside their interaction with ion channel and their influence on plasma membrane fluidity, probably the main effect is acting as competitor for cytochrome P-450 (CYP) with respect to ω-6 FA. Thus, they can modulate the biosynthesis of eicosanoids and other lipid mediators, which likely exert a protective action. Another suggestive hypothesis is that their beneficial effect is not dependent only on the intake of ω-3 FA, but also on the complex interaction between different nutrients including ω-3 and other FAs with polymorphisms in genes involved in ω-3 FA modulation. This complex interaction has seldom been explored in children and adolescents. Further studies are needed to investigate all these points in order to find a better collocation of ω-3 FA on the available armamentarium for preventive, possibly individualized, medicine. Copyright © 2015 Elsevier Inc. All rights reserved.