Versatile roles of lipids and carotenoids in membranes

Chemical characteristics and functions of constitutive membrane lipids, fatty acids and carotenoids, are summarized. Lipids and carotenoids are major components of biological membranes, and perform several important physiological and structural functions in all kingdoms of living organisms. Structural lipids build up and maintain the architecture of biological membrane, while active lipids originating from membranes have signaling functions. Unsaturated lipids protect photosynthetic organisms against low-temperature photoinhibition and keep necessary membrane microviscosity under various environmental conditions. Sterols are capable of controlling membrane order and segregation of lipids into rafts by intercalating between phospholipids. Carotenoids are essential structural and functional components of photosynthetic complexes and membranes in plants, algae and cyanobacteria. They have a role in light harvesting processes and the elimination of excitation energy. They can serve as protectant agents against reactive oxygen and nitrogen species. Heat dissipation is involved in protective processes. Carotenoids are effective quenchers and scavengers of singlet oxygen and other free radicals, therefore they suppress lipid peroxidation and other harmful biochemical reactions. Carotenoids are indispensable antioxidants in photosynthetic organisms and also in animals, which are not capable of synthesizing them. Both carotenoids and essential lipid species are necessary for human diet

Selective modification of cytoplasmic membrane fluidity by catalytic hydrogenation provides evidence on its primary role in chilling susceptibility of the blue-green alga, Anacystis nidulans

AbstractCytoplasmic and thylakoid membranes were isolated at different stages of catalytic hydrogenation of fatty acyl double bonds in living cells of Anacystis nidulans. The reaction was limited to the lipids of cell-surface membranes during the initial period of hydrogenation, thus, we were able to produce alga cells, modified exclusively in the cytoplasmic membrane. In these unique cells, neither compositional nor physical changes were detected in the lipid phase of thylakoids. Due to the rigidification of the alkyl chains of its lipids, however, the cytoplasmic membrane became leaky and phase separated at considerably higher chilling temperatures.Since an irreversible inactivation of photosynthetic electron transport was found simultaneously, it provided direct evidence for the hypothesis that the thermotropic properties of the lipids within cytoplasmic membranes, and not those of the thylakoids, control chilling susceptibility of the blue-green alga, A.nidulans

Increased plasma von Willebrand factor antigen levels but normal von Willebrand factor cleaving protease (ADAMTS13) activity in preeclampsia.

The activity of ADAMTS13, the von Willebrand factor (VWF) cleaving protease is low in several conditions, including HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome. As HELLP syndrome develops in most cases on the basis of preeclampsia, our aim was to determine whether plasma ADAMTS13 activity is decreased in preeclampsia. Sixty-seven preeclamptic patients, 70 healthy pregnant women and 59 healthy non-pregnant women were involved in this case-control study. Plasma ADAMTS13 activity was determined with the FRETS-VWF73 assay, while VWF antigen (VWF:Ag) levels with an enzyme-linked immunosorbent assay. The multimeric pattern of VWF was analyzed by SDS-agarose gel electrophoresis. There was no significant difference in plasma ADAMTS13 activity between the preeclamptic and the healthy pregnant and non-pregnant groups (median [25-75 percentile]: 98.8 [76.5-112.8] %, 96.3 [85.6-116.2] % and 91.6 [78.5-104.4] %, respectively; p > 0.05). However, plasma VWF:Ag levels were significantly higher in preeclamptic patients than in healthy pregnant and non-pregnant women (187.1 [145.6-243.1] % versus 129.3 [105.1-182.8] % and 70.0 [60.2-87.3] %, respectively; p < 0.001). The multimeric pattern of VWF was normal in each group. Primiparas had lower plasma ADAMTS13 activity than multi-paras (92.6 [75.8-110.6] % versus 104.2 [92.1-120.8] %; p = 0.011). No other relationship was found between clinical characteristics, laboratory parameters and plasma ADAMTS13 activity in either study group. In conclusion, plasma ADAMTS13 activity is normal in preeclampsia despite the increased VWF:Ag levels. However, further studies are needed to determine whether a decrease in plasma ADAMTS13 activity could predispose preeclamptic patients to develop HELLP syndrome

Levels of von Willebrand factor antigen and von Willebrand factor cleaving protease (ADAMTS13) activity predict clinical events in chronic heart failure.

Decreased activity of ADAMTS13, the von Willebrand factor (VWF) cleaving protease, was recently reported in cardiovascular diseases and in hepatic failure. Chronic heart failure (CHF) is characterised by abnormalities of left ventricular function accompanied by the failure of the liver and dysregulation of endothelial activation. Therefore, the aim of our study was to measure ADAMTS13 activity in CHF, and determine the prognostic value of VWF and ADAMTS13 on major clinical events in CHF. ADAMTS13 activity (measured by FRETS-VWF73 substrate) was decreased in CHF (n = 152, left ventricular ejection fraction <45%), and it correlated negatively with B-type natriuretic peptide (BNP) NYHA (New York Heart Association) classes, markers of synthetic capacity of the liver and endothelial dysfunction (all p < 0.005). Both, high VWF:Ag levels (hazard ratio [HR] 1.52, 95% confidence interval [CI] 1.189-1.943), and low ADAMTS13/VWF:Ag ratios (HR 0.70, 95% CI 0.58-0.84) independently and significantly predicted short-term (1 year follow-up) clinical adverse events in heart failure (HF). Decreased activity of ADAMTS13 with concomitant high VWF:Ag levels is a significant independent predictor of clinical events in CHF. The levels of the two molecules may integrate the impaired synthetic capacity of the liver and the disturbed endothelial regulation and can therefore be a useful tool to predict clinical events in CHF

INVESTIGATION OF PORE SIZE AND RESIN ABSORBENCY IN CHOPPED STRAND MATS

The main aim was to measure and evaluate the absorption ability of resins in glass fiber mats most often used in Hungary since pore size influences the absorbance process and the absorbed quantity of resin during composite production when the resin is still in a liquid phase. The average value of pores and their distribution function were estimated using the mat statistic model and the measured geometrical parameters. The measurement and evaluation method developed can be used to model the liquid absorbance process of glass fiber mats and to measure the mass of absorbed resin and the rate of absorption. A good theoretical approximation was also obtained for describing the resin absorbency of glass fiber mats. It was found that there is a linear relationship between the pore sizes estimated with the help of the statistic fiber mat model and the uptake rate

Membrane dynamics as seen by Fourier transform infrared spectroscopy in a cyanobacterium, Synechocystis PCC 6803 The effects of lipid unsaturation and the protein-to-lipid ratio

AbstractThe roles of lipid unsaturation and lipid-protein interactions in maintaining the physiologically required membrane dynamics were investigated in a cyanobacterium strain, Synechocystis PCC 6803. The specific effects of lipid unsaturation on the membrane structure were addressed by the use of desaturase-deficient (desA−/desD−) mutant cells (which contain only oleic acid as unsaturated fatty acid species) of Synechocystis PCC 6803. The dynamic properties of the membranes were determined from the temperature dependence of the symmetric CH2 stretching vibration frequency, which is indicative of the lipid fatty acyl chain disorder. It was found that a similar membrane dynamics is maintained at any growth temperature, in both the wild-type and the mutant cell membranes, with the exception of mutant cells grown at the lower physiological temperature limit. It seems that in the physiological temperature range the desaturase system of the cells can modulate the level of lipid desaturation sufficiently to maintain similar membrane dynamics. Below the range of normal growth temperatures, however, the extent of lipid disorder was always higher in the thylakoid than in the cytoplasmic membranes prepared from the same cells. This difference was attributed to the considerable difference in protein-to-lipid ratio in the two kinds of membranes, as determined from the ratio of the intensities of the protein amide I band and the lipid ester CO vibration. The contributions to the membrane dynamics of an ab ovo present ‘structural’ lipid disorder due to the protein–lipid interactions and of a thermally induced ‘dynamic’ lipid disorder could be distinguished

EPR study of thylakoid membrane dynamics in mutants of the carotenoid biosynthesis pathway of Synechocystis sp. PCC6803

EPR spectroscopy using 5-doxylstearic acid (5-SASL) and 16-doxylstearic acid (16-SASL) spin probes was used to study the fluidity of thylakoid membranes. These were isolated from wild type Synechocystis and from several mutants in genes encoding selected enzymes of the carotenoid biosynthesis pathway and/or acyl-lipid desaturases. Cyanobacteria were cultivated at 25°C and 35°C under different light regimes: photoautotrophically (PAG) and/or in light-activated heterotrophic conditions (LAHG). The relative fluidity of membranes was estimated from EPR spectra based on the empirical outermost splitting parameter in a temperature range from 15°C to 40°C. Our findings demonstrate that in native thylakoid membranes the elimination of xanthophylls decreased fluidity in the inner membrane region under optimal growth conditions (25°C) and increased it under sublethal heat stress (35°C). This indicated that the overall fluidity of native photosynthetic membranes in cyanobacteria may be influenced by the ratio of polar to non-polar carotenoid pools under different environmental conditions

Production of highly nutritious functional food with the supplementation of wheat flour with lysine

L

A több évtizeden át tartó testedzés hatása az irizin hormon szintjére

Kutatásunk során célul tűztük ki, hogy felderítsük az élethosszon át tartó edzés hatását a vér irizin szintjére. Vizsgálatunkban edzett és nem edzett közép/időskorú személyek vettek részt. Az irizin hormon, ami egy myokin és adipokin, a fizikai aktivitás során termelődik a peroxiszóma proliferátor aktivált receptor gamma koaktivátor 1 alfa (PGC1A) fehérje jelenlétében. Az irizin számos fontos élettani hatással bír, melyek főként fizikai aktivitás hatására aktiválódnak. Elsősorban a szervezet anyagcsere folyamatait szabályozza, de kapcsolatba hozták már az agyműködéssel és a telomer hosszal is. Legjobb tudomásunk szerint korábban nem vizsgálták még a több évtizedes edzés hatását az irizinre. Eredményeink alapján azt találtuk, hogy az irizin hormon szintje nem mutat korrelációt a VO2max értékkel. Többváltozós regressziós analízis alkalmazása során az irizin és a HDL koncentrációja a vérben korrelációt mutatott egymással a különböző funkcionális paraméterek figyelembe vétele mellett. Maximális erő mérés eredményei alapján az edzett és az edzetlen férfi csoport nagyobb maximális erővel rendelkezik, mint az edzett és edzetlen női csoport, azonban a két férfi csoport között nem mutatható ki különbség. Az edzett férfiak robbanékony ereje nagyobb a két női csoporthoz képest. A becsült VO2max értékek szignifikánsan magasabbak az edzett férfi csoportban az edzetlen csoportokhoz képest. Az edzett nők magasabb HDL szinttel rendelkeznek, mint az edzetlen férfiak és az edzetlen nők. A HDL, mint előnyös funkciókkal rendelkező lipoprotein, elképzelhető, hogy hasonló élettani adaptációs folyamatok mentén fejti ki a hatásait, mint az irizin. A VO2max és az irizin szint között nem találtunk korrelációt, amiből arra következtethetünk, hogy az edzésre adott élettani válaszok komplexebbek annál, minthogy egyetlen mutatóval próbáljuk meg jellemezni azt