Photoregulated "Breathing" Vesicle with Inversed Supramolecular Chirality.

Though phospholipids possess chiral centers, their chiral aggregation within bilayer cell membranes has seldom been referred and recognized. Insight into the chirality at higher levels in artificial molecular bilayer assemblies such as vesicles or liposomes is important to better understand biomembrane functions. In this work, we illustrate the fabrication of chiral vesicles with photoresponsive supramolecular chirality and structural transformation property. Cholesterol was conjugated to azobenzene via different spacers, of which molecular chirality underwent transfer to supramolecular level upon aggregation in water. The resultant building block self-assembled into unilamellar vesicles that could respond to light irradiation by showing reversible extension/contraction behavior. Such "breathing" behavior was accompanied with supramolecular chirality inversion from M- to P-handedness, confirmed by the solid-state crystal structure and electronic circular dichroism spectra based on density functional theory. The vesicle membrane behaves as a matrix to accommodate guest molecules via aromatic interactions, which significantly elevated the UV light resistance with respect to the structural and supramolecular chirality transformation. This work offers an unprecedented rational control over supramolecular chirality using photoresponsiveness in vesicular membranes.

Dye-Loaded Quatsomes Exhibiting FRET as Nanoprobes for Bioimaging.

Fluorescent organic nanoparticles (FONs) are emerging as an attractive alternative to the well-established fluorescent inorganic nanoparticles or small organic dyes. Their proper design allows one to obtain biocompatible probes with superior brightness and high photostability, although usually affected by low colloidal stability. Herein, we present a type of FONs with outstanding photophysical and physicochemical properties in-line with the stringent requirements for biomedical applications. These FONs are based on quatsome (QS) nanovesicles containing a pair of fluorescent carbocyanine molecules that give rise to Förster resonance energy transfer (FRET). Structural homogeneity, high brightness, photostability, and high FRET efficiency make these FONs a promising class of optical bioprobes. Loaded QSs have been used for in vitro bioimaging, demonstrating the nanovesicle membrane integrity after cell internalization, and the possibility to monitor the intracellular vesicle fate. Taken together, the proposed QSs loaded with a FRET pair constitute a promising platform for bioimaging and theranostics.

Determination of free cholesterol oxide products in food samples by gas chromatography and accelerated solvent extraction: influence of electron-beam irradiation on cholesterol oxide formation.

BACKGROUND: The aim of this study was to develop an efficient method for cholesterol oxide product (COP) determination in irradiated and non-irradiated ready-to-eat foods with high water content by gas chromatography-flame ionisation detector after accelerated solvent extraction (ASE), and derivatisation with a silylating reagent. RESULTS: The ASE solvent was an 85:15 v/v petroleum ether/chloroform mixture at 40 °C and 1500 psi followed by solid phase extraction. The ASE method was compared with the established lixiviation method, proving an advantageous alternative which reduces analysis time by a factor of 15 and solvent volume by 50%, and minimises the use of chlorinated solvents. COP derivative structures were identified by gas chromatography coupled with mass spectrometry. Analytical characteristics were determined from standards and recoveries were 63-95%, establishing the validity of the method. CONCLUSION: The results obtained and their analysis by chemometric techniques established COP formation in food samples after e-beam irradiation. Increase in COP concentration depended on both irradiation doses and food composition, mainly water and fat content, although linear correlations among variables were not found. © 2016 Society of Chemical Industry.

Lasing in imperfectly aligned cholesterics.

Optically pumped light emissions in imperfectly aligned dye-doped cholesteric cells with glance and frosted glass substrates of three different cell gap thicknesses are experimentally studied. Alignment imperfections show up in emission spectra by a broadening of the photonic bandgap (PhBG) lasing (allowed) lines at short- and long-wavelength PhBG edges and by an additional (forbidden) emission line inside the PhBG. Forbidden and allowed lines differ distinctively by their stability in the course of pumping. The origin of the forbidden line is discussed.

Effects of 10-GHz microwaves on hematological parameters in Swiss albino mice and their modulation by Prunus avium.

The objective of this study was to investigate the modulatory role of Prunus avium fruit extract (PAE) on several blood parameters after exposure to 10-GHz microwaves. Swiss albino mice from an inbred colony were selected and divided into 3 groups. Mice in group I served as the control; they were placed in a Plexiglas cage (without energizing the system) for 2 hours/day for 30 consecutive days. Group II mice were exposed to 10-GHz microwaves for 2 hours/day for 30 consecutive days. Mice in group III received PAE (500 mg/kg/body weight) orally once daily 1 hour before exposure to 10-GHz microwaves (2 hours/day) for 30 consecutive days. After 30 days of treatment, blood samples were collected from mice in all groups and analyzed. Hemoglobin, monocytes, packed cell volume, red blood cells, mean corpuscular hemoglobin concentration declined significantly (P ≤ 0.01), whereas white blood cells, lymphocytes, erythrocyte sedimentation rate, and mean corpuscular volume increased significantly (P ≤ 0.01) compared to the control group (group I). Cholesterol, alkaline phosphatase, and lipid peroxidation also increased significantly (P ≤ 0.01). Depletion in blood sugar, total protein, acid phosphatase, and glutathione levels was noted after microwave exposure compared with levels in the sham-exposed (control) mice. Histopathological alterations in blood cells also were seen. Signs of improvements in the hematological, biochemical, and histopathological parameters were recorded in group III, where PAE was supplemented before exposure. Exposure to microwaves influences hematological parameters, which could be ameliorated by the supplementation of PAE.

[The development of method of intravenous laser irradiation of blood with green laser in patients with hyperlipidemia].

The impact of intravenous laser irradiation of blood with green laser in patients with hyperlipidemia was investigated. The blood of patients was chosen as sample for analysis. The patients were divided in two groups: patients with atherosclerosis of various localization and patients with atherosclerosis associated with diabetes mellitus. The effectiveness of laser impact was evaluated according the blood biochemical indicators. The levels of crude cholesterol, triglycerides, low and very low density lipoproteins, apoproteins A and B, highly sensitive C-reactive protein, atherogenity indicator, glucose content, uric acid content were determined befor and after 1, 3 and 6 months after impact. The study results indicate the occurrence of hypolipedemic and hypoglycemic effects.

Color changing and lasing stretchable cholesteric films.

Polymer materials able to change reflective properties due to mechanical deformation fundamentally challenge the theory of soft materials and are important for a number of emerging applications. The most promising of those are chiral lasers. In this communication, we report novel cholesteric materials that display large color change from far red to blue and a shift of the position of the selective reflection band under uniaxial strain from near infrared to ultraviolet. Optical pumping of these materials which are doped with laser dyes, leads to lasing at the wavelengths controlled by strain within the emission interval of laser dyes of 80 nm.

Spectral monitoring of photoirradiated skin lipids: MS and IR approaches.

An investigation of the effects of UV(A) irradiation on the stratum corneum lipids was carried out in vitro on films. The modifications of their conformational order were studied by FTIR and the formation of new entities was detected by mass spectroscopy. The results show not only differences in behaviour of the three lipid classes (fatty acids (FA), ceramides (CER), and cholesterol), but also variation within a class, depending on the molecules structure. Upon UV(A) irradiation, beta scission occurs on all the components, saturated and unsaturated. Moreover, unsaturated FA or CER having a double bond on their FA moiety may become saturated or may be transformed into their free radical form. Unsaturated FA are more sensitive to UV(A) and lead more easily to oxygenated components than unsaturated CER. The chemical effects are irradiation dose dependent but do not deeply influence the supramolecular organisation of these lipids. The global conformation of the lipids stays in an orthorhombic state, a decrease of the packing density however is observed.

Does the electric Lehmann effect exist in cholesteric liquid crystals?

Experiments have shown that cholesteric droplets or cholesteric fingers may be put into motion by the action of an electric field. The former rotate whereas the latter drift perpendicularly to their axes. In all cases, the texture moves without visible material transport. The electric Lehmann effect was initially used to interpret these observations but, recently, alternative explanations were found, based on electrohydrodynamics. Another experiment in this area was that of Padmini and Madhusudana (Liq. Cryst. 14, 497 (1993)). Performed in 1993 with a compensated cholesteric liquid crystal under fixed planar boundary conditions, it was also explained in terms of electric Lehmann effect. We conducted the same experiment and extended it to a pi -twisted planar geometry. Although our experimental results agree with those of Padmini and Madhusudana, we demonstrate that they are incompatible with an electric Lehmann effect. By contrast, an explanation based on flexoelectricity allows us to interpret the whole data set obtained in both geometries. The consequence is that there is at the moment no clear experimental evidence of the electric Lehmann effect.

Further investigations on the role of ascorbic acid in stratum corneum lipid models after UV exposure.

This study is the continuation of our research into vitamin C and its possible effects on human skin after topical administration. The effects of ascorbic acid, iron ions and UV irradiation on stratum corneum lipid models were investigated. The lipid models used were: a simple system (linolenic acid dispersion), a complex system (liposomes consisting of dipalmitoylphosphatidylcholine, cholesterol and linolenic acid) and complex systems with additionally incorporated ceramides (types III and IV). The lipid peroxidation was quantified by the thiobarbituric acid assay. A human adult low-calcium high-temperature (HaCaT) keratinocytes cell culture was used as a second in-vitro model. The amount of intracellular peroxides was determined by measuring the fluorescence intensity using the dihydrorhodamine 123 assay. Electron paramagnetic resonance spectroscopy was used to study the influence of ascorbic acid and iron ions on the signal intensity of 5-doxylstearic acid during UV exposure. Ascorbic acid showed prooxidative properties in the thiobarbituric acid assay whereas cell protection was measured in the HaCaT keratinocytes experiments. Electron paramagnetic resonance investigations revealed different extents of free radical production generated by iron ions, ascorbic acid and UV irradiation. In evaluating the results from this study new aspects of the mechanism of lipid damage caused by these three factors were suggested, transcending the simple redox behaviour of ascorbic acid.

Self-sensitized photodegradation of membrane-bound protoporphyrin mediated by chain lipid peroxidation: inhibition by nitric oxide with sustained singlet oxygen damage.

In the presence of exciting light, iron and reductants, the singlet oxygen (1O2)-generating sensitizer protoporphyrin IX (PpIX) induces free radical lipid peroxidation in membranes, but gradually degrades in the process. We postulated that NO, acting as a chain-breaking antioxidant, would protect PpIX against degradation and consequently prolong its ability to produce 1O2. This idea was tested by irradiating PpIX-containing liposomes (LUVs) in the presence of iron and ascorbate, and monitoring the cholesterol hydroperoxides 5alpha-OOH and 7alpha/beta-OOH as respective 1O2 and free radical reporters. 5alpha-OOH accumulation, initially linear with light fluence, slowed progressively after prolonged irradiation, whereas 7alpha/beta-OOH accumulation only accelerated after an initial lag. The active, but not spent, NO donor spermine NONOate (0.4 mM) virtually abolished 7alpha/beta-OOH buildup as well as 5alpha-OOH slowdown. Increasing membrane phospholipid unsaturation hastened the onset of rapid chain peroxidation and 5alpha-OOH slowdown. Accompanying the 5alpha-OOH effect was a steady decrease in 1O2 quantum yield and PpIX fluorescence at 632 nm, both of which were inhibited by NO. An NO-inhibitable decay of PpIX fluorescence was also observed during dark incubation of 5alpha-OOH-bearing LUVs with iron and ascorbate, confirming a link between chain peroxidation and PpIX loss. By protecting PpIX in irradiated membranes, NO might select for and prolong purely 1O2-mediated damage. Supporting this was our observation that 1O2-mediated photoinactivation of a nonmembrane target, lactate dehydrogenase, slowed concurrently with 5alpha-OOH accumulation and that spermine NONOate prevented this. Thus, NO not only protected membrane lipids against PpIX-sensitized free radical damage, but PpIX itself, thereby extending its 1O2-generating lifetime. Consistent findings were obtained using porphyrin-sensitized COH-BR1 cells. These previously unrecognized effects of NO could have important bearing on 5-aminolevulinate-based photodynamic therapy in which PpIX is metabolically deposited in tumor cells.

Electric field-driven transformations of a supported model biological membrane--an electrochemical and neutron reflectivity study.

A mixed bilayer of cholesterol and dimyristoylphosphatidylcholine has been formed on a gold-coated block of quartz by fusion of small unilamellar vesicles. The formation of this bilayer lipid membrane on a conductive surface allowed us to study the influence of the support's surface charge on the structure and hydration of the bilayer lipid membrane. We have employed electrochemical measurements and the specular reflection of neutrons to measure the thickness and water content in the bilayer lipid membrane as a function of the charge on the support's surface. When the surface charge density is close to zero, the lipid vesicles fuse directly on the surface to form a bilayer with a small number of defects and hence small water content. When the support's surface is negatively charged the film swells and incorporates water. When the charge density is more negative than -8 micro C cm(-2), the bilayer starts to detach from the metal surface. However, it remains in a close proximity to the metal electrode, being suspended on a thin cushion of the electrolyte. The field-driven transformations of the bilayer lead to significant changes in the film thicknesses. At charge densities more negative than -20 micro C cm(-2), the bilayer is approximately 37 A thick and this number is comparable to the thickness determined for hydrated multilayers of dimyristoylphosphatidylcholine from x-ray diffraction experiments. The thickness of the bilayer decreases at smaller charge densities to become equal to approximately 26 A at zero charge. This result indicates that the tilt of the acyl chains with respect to the bilayer normal changes from approximately 35 degrees to 59 degrees by moving from high negative charges (and potentials) to zero charge on the metal.

Mass spectrometric examinations of stratum corneum lipid models exposed to ultraviolet irradiation.

Lipid model systems consisting of the major components of the stratum corneum intercellular lipid matrix were studied to investigate the ultraviolet-radiation-mediated damage of these biomolecules. Pure lipids and liposomes were irradiated using a lamp emitting a solar radiation spectrum. The influences of the irradiation and the effects of added iron ions were studied by electrospray ionization mass spectrometry (MS) with an ion trap analyser. Exact mass measurements were carried out using a time-of-flight mass spectrometer. Only linolenic acid and cholesterol were found to be subject to oxidative changes caused by UV irradiation whereas the other lipids examined (dipalmitoylphosphatidylcholine, ceramide III and cholesterol sulphate) were stable to oxidative stress. Several lipid adducts were observed upon analysis of the liposomes. The composition of these adducts was identified by MS/MS experiments.

The examination of skin lipid model systems stressed by ultraviolet irradiation in the presence of transition metal ions.

In this study, we investigated the effects of ultraviolet (UV) radiation on lipid peroxidation in the presence of ionised iron as a transition metal. Fatty acids as important intercellular stratum corneum lipids and liposomes were used to model skin lipid systems for our experiments. A UV-A laser and a broad spectrum UV lamp were used to create high-level radiation. UV-related damage was quantified by the thiobarbituric acid assay detecting malondialdehyde. Electrospray mass spectrometry was used to characterise peroxidation products following UV exposure. We have shown that hydro- and endoperoxides are long stable intermediates deriving from lipid peroxidation. The incorporation of unsaturated fatty acids into phospholipid liposomes increased the average liposomal diameter and enhanced sensitivity to UV radiation. By comparing our data from laser induced monochromatic UV-A radiation and broad-spectrum UV irradiation, we have demonstrated that UV-A radiation can also induce lipid peroxidation in lipid model systems.

Modulation of radiation-induced organs toxicity by cremophor-el in experimental animals.

Pharmacological and cytogenetic evaluations of the protective effects of polyethoxylated castor oil cremophor-EL (cremophor) against hepato, renal and bone marrow toxicity induced by gamma irradiation in normal rats were carried out. A single dose of irradiation (6 Gy) caused hepatic and renal damage manifested biochemically as an elevation in levels of serum alanine and aspartate aminotransferase as well as an increase in blood urea. Cremophor administration at a dose level of 50 microl kg-1 intravenously 1 day before exposure to irradiation (6 Gy) protected the liver and kidney as indicated by the recovery of levels of hepatic aminotransferase, urea and lipid profiles to normal values. Gamma irradiation of male rats caused a decrease in reduced glutathione and an increase in the oxidized form in rat-liver homogenate. A highly significant increase in the incidence of micronucleated normochromatic erythrocytes and micronucleated polychromatic erythrocytes was observed after irradiation exposure. The induced genotoxicity in the bone marrow cells was corrected by pretreatment with cremophor. The findings of this study suggest that cremophor pretreatment can potentially be used clinically to prevent irradiation-induced hepato, renal and bone marrow toxicity without interference with its cytotoxic activity.

Singlet oxygen adducts of cholesterol: photogeneration and reductive turnover in membrane systems.

Identification of signature products provides a powerful means for establishing whether singlet molecular oxygen (1O2) is a reactive intermediate in a photodynamic process. This approach is particularly attractive for biological systems in which direct physical measurement is difficult because of the short lifetime of 1O2. Among the many possible reporter molecules in a target system, cholesterol (Ch) has the advantage of affording a limited number of readily distinguishable oxidation products, among which are the hydroperoxides 3 beta-hydroxy-5 alpha-cholest-6-ene-5-hydroperoxide (5 alpha-OOH), 3 beta-hydroxycholest-4-ene-6 alpha-hydroperoxide (6 alpha-OOH) and 3 beta-hydroxycholest-4-ene-6 beta-hydroperoxide (6 beta-OOH) that derive specifically from 1O2 addition. The purpose of this study was to compare these species in terms of (1) rates of accumulation in photodynamically treated liposomal membranes; (2) susceptibility to iron-mediated 1 e- reduction that triggers chain peroxidative damage; (3) susceptibility to selenoperoxidase (phospholipid hydroperoxide glutathione peroxidase [PHGPX])-mediated 2 e- reduction that protects against such damage and (4) relative toxicity to mammalian cells. Our results indicate that 5 alpha-OOH is photogenerated at a much greater initial rate than 6 alpha-OOH or 6 beta-OOH. Although liposomal 5 alpha-OOH, 6 alpha-OOH, and 6 beta-OOH exhibit similar first-order decay kinetics during iron/ascorbate treatment, the former decays much more slowly during GSH/PHGPX treatment, and is more toxic to L1210 cells. These and related findings suggest that 5 alpha-OOH is potentially the most damaging ChOOH to arise in photodynamically treated cells.

Seasonal variation of blood cholesterol levels: study methodology.

This manuscript provides a description of the methodology used in the Seasonal Variation of Blood Cholesterol Levels (SEASON) study, with the intent of informing the scientific community of the available data sets and to invite a dialogue with scientists in complementary fields. The primary aim of the SEASON study is to describe and delineate the causes of seasonal variation of blood lipid levels in the general population. This research project is designed specifically to systematically collect and analyze a number of important variables necessary to study the role of seasonality in blood lipids and relevant covariates.

Photobleaching of arterial fluorescent compounds: characterization of elastin, collagen and cholesterol time-resolved spectra during prolonged ultraviolet irradiation.

To study the photobleaching of the main fluorescent compounds of the arterial wall, we repeatedly measured the time-resolved fluorescence of elastin, collagen and cholesterol during 560 s of excitation with nitrogen laser pulses. Three fluence rate levels were used: 0.72, 7.25 and 21.75 microW/mm2. The irradiation-related changes of the fluorescence intensity and of the time-resolved fluorescence decay constants were characterized for the emission at 390, 430 and 470 nm. The fluorescence intensity at 390 nm decreased by 25-35% when the fluence delivered was 4 mJ/mm2, a common value in fluorescence studies of the arterial wall. Cholesterol fluorescence photobleached the most, and elastin fluorescence photobleached the least. Photobleaching was most intense at 390 nm and least intense at 470 nm such that the emission spectra of the three compounds were markedly distorted by photobleaching. The time-resolved decay constants and the fluorescence lifetime were not altered by irradiation when the fluence was below 4 mJ/mm2. The spectral distortions associated with photobleaching complicate the interpretation of arterial wall fluorescence in terms of tissue content in elastin, collagen and cholesterol. Use of the time-dependent features of the emission that are not altered by photobleaching should increase the accuracy of arterial wall analysis by fluorescence spectroscopy.

Pantothenol protects rats against some deleterious effects of gamma radiation.

Rats were exposed to gamma radiation from a 60Co source, receiving 0.25 Gy at weekly intervals. During 2 d before each irradiation, the animals received daily intragastric doses of 26 mg pantothenol or 15 mg beta-carotene per kg body weight. One hour after the third irradiation session, the animals were killed and their livers were analyzed. In animals not supplied with pantothenol, the irradiation resulted in a significant decrease of total liver lipids and a 50% decrease in phospholipids. Liver cholesterol was decreased by about 20%. Irradiation produced lipid peroxidation as expressed by doubling of the amounts of conjugated dienes and ketone dienes and of thiobarbituric acid reactive compounds. The amount of CoA in liver was decreased by 24% and that of reduced glutathione by 40%. The NAD+/NADH ratio was increased by 60% and the activity of NADP-dependent malate dehydrogenase (decarboxylating) was decreased by 26%. The amount of pantothenic acid and its derivatives (expressed as pantolactone-generating compounds) in blood decreased by about 80%. In rats to which pantothenol was administered, the content of pantothenic acid in blood was tripled compared to nonirradiated (control) rats, and all the biochemical parameters measured in liver were the same as in nonirradiated animals.