Electron Paramagnetic Resonance Gives Evidence for the Presence of Type 1 Gonadotropin-Releasing Hormone Receptor (GnRH-R) in Subdomains of Lipid Rafts.

This study investigated the effect of type 1 gonadotropin releasing hormone receptor (GnRH-R) localization within lipid rafts on the properties of plasma membrane (PM) nanodomain structure. Confocal microscopy revealed colocalization of PM-localized GnRH-R with GM-enriched raft-like PM subdomains. Electron paramagnetic resonance spectroscopy (EPR) of a membrane-partitioned spin probe was then used to study PM fluidity of immortalized pituitary gonadotrope cell line αT3-1 and HEK-293 cells stably expressing GnRH-R and compared it with their corresponding controls (αT4 and HEK-293 cells).

Microstructure evaluation of dermally applicable liquid crystals as a function of water content and temperature: Can electron paramagnetic resonance provide complementary data?

Insight into the microstructure of lyotropic liquid crystals (LCs) is of crucial importance for development of novel dermal delivery systems. Our aim was to evaluate the phase behaviour of dermally applicable LCs composed of isopropyl myristate/Tween 80/lecithin/water, along the dilution line, where phase transitions are predominantly driven by increased water content. Additionally, identification of LC temperature dependence is of great importance for skin application.

How perifosine affects liposome-encapsulated drug delivery across a cell barrier.

Background: The development of efficient drug delivery systems to transport therapeutics across barrier-forming cells remains a challenge. Recently it was shown that liposomes containing perifosine, a synthetic analog of lysophosphatidylcholine, efficiently deliver liposome encapsulated content across barrier-forming cells.

Methods: To elucidate the mechanism of the delivery, fluorescent and spin labeled analog of perifosine were synthesized and their transport from liposomes to the barrier-forming MDKC cells was measured.

Interaction of antidepressant drug, clomipramine, with model and biological stratum corneum membrane as studied by electron paramagnetic resonance.

The interactions of tricyclic antidepressant drug, clomipramine (CLO), with pig ear stratum corneum (SC) and model membranes were investigated by electron paramagnetic resonance (EPR) spin labeling to get some insight into the possible application of this drug in transdermal delivery. The changes in membrane characteristics caused by CLO in the regions that are close to the water-lipid interfaces and the central parts of the membranes were searched. The experimental results were supported by computer simulation of EPR spectra, which showed heterogeneity of the membranes composed of regions with different fluidity characteristics.

Effect of flavonoid structure on the fluidity of model lipid membranes.

We investigated how the structural properties of (+)-catechin, (-)-epicatechin, (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG) and butylated hydroxytoluene (BHT) correlate with structural changes of phosphatidylcholine plus sphingomyelin (2.4:1) model lipid membranes. Changes were measured by fluorescence anisotropy, electron paramagnetic resonance, and differential scanning calorimetry.

Periodontal disease, periodontal treatment and systemic nitric oxide in dogs.

Thirty-two client-owned dogs treated for periodontal disease were divided in group 1 if no periodontitis, group 2 if ≤25%, and group 3 if >25% of the teeth present were affected with periodontitis. Blood was tested before and 2 weeks after periodontal therapy for nitrosyl hemoglobin (HbNO), plasma nitrite/nitrate (NOx) and 3-nitrotyrosine (NT) levels. No HbNO was detected in any of the animals tested.

Effect of growth medium pH of Aeropyrum pernix on structural properties and fluidity of archaeosomes.

The influence of pH (6.0; 7.0; 8.

Structural characterization of liposomes made of diether archaeal lipids and dipalmitoyl-L-α-phosphatidylcholine.

The physicochemical properties of binary lipid mixtures of diether C(25,25) lipids and dipalmitoyl-L-α-phosphatidylcholine (DPPC) were studied using photon correlation, fluorescence and electron paramagnetic resonance spectroscopy, and transmission electron microscopy. These two types of lipids can be mixed at all molar ratios to form unilamellar and multilamellar liposomes. Fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatrien in mixed liposomes indicates that the abrupt changes in order parameter in the hydrophobic part of bilayer membranes made of DPPC lipids disappears with increasing mol%C(25,25) lipids.

Early systemic inflammatory response in mice after a single oral gavage with live Escherichia coli is evidenced by increased TNF-alpha and nitric oxide production.

Twenty-four female BALB/c mice were orally inoculated with 10(8) CFU Escherichia coli ATCC 25922 and euthanized 2.5, 7, 13 and 25 h post-inoculation. The levels of organ nitric oxide (NO) and plasma endotoxin, TNF-alpha and nitrite/nitrate (NO(x)) were compared to those found in sham-inoculated mice, to evaluate systemic host-response to a low-level oral exposure to Gram-negative bacteria.

Modulation of tumor hypoxia by topical formulations with vasodilators for enhancing therapy.

Tumor hypoxia is a well known therapeutic problem which contributes to radioresistance and aggressive tumor characteristics. Lack of techniques for repeated measurements of tumor oxygenation (pO(2), partial pressure of oxygen) has restricted the optimization of hypoxia modifying methods and their efficacious application with radiotherapy. We have investigated a non-invasive method to enhance tissue pO(2) of peripheral tumors using topical application of formulations with BN (Benzyl Nicotinate), a vasodilator, and have used EPR (Electron Paramagnetic Resonance) oximetry to follow its effect on tumor oxygenation.

Stability of diether C(25,25) liposomes from the hyperthermophilic archaeon Aeropyrum pernix K1.

Temperature and pH effects were studied for stability, structural organization, fluidity and permeability of vesicles from a polar lipid methanol fraction isolated from the Aeropyrum pernix. We determined the permeability of C(25,25) liposomes using fluorescence intensity of released calcein. At pH 7.

On the surface properties of oleate micelles and oleic acid/oleate vesicles studied by spin labeling.

Dilute aqueous systems composed of sodium oleate micelles and sodium oleate/oleic acid vesicles were investigated as a function of pH by electron spin resonance spectroscopy with TEMPO-stearate TEMPO-stearamide as well as with a positively charged water soluble spin label, TEMPO-choline. The dynamics of the three TEMPO-spin labels were found to be sensitive to changes in the interfacial region of the aggregates as a function of pH. The results obtained are consistent with the formation of a hydrogen bond network (RCOO(-)↔HOOCR) at the surface of the sodium oleate/oleic acid system in the course of the transformation of micelles into the closed bilayers (vesicles).

Study of radiation induced changes of phosphorus metabolism in mice by (31)P NMR spectroscopy.

Background: The aim of this study was to examine whether (31)P NMR can efficiently detect X-ray radiation induced changes of energy metabolism in mice. Exposure to ionizing radiation causes changes in energy supply that are associated with the tissue damage because of oxidative stress and uncoupled oxidative phosphorylation. This has as a consequence decreased phosphocreatine to adenosine triphosphate ratio (Pcr/ATP) as well as increased creatine kinase (CK) and liver enzymes (transaminases AST and ALT) levels in serum.

EPR investigation of clomipramine interaction with phosphatidylcholine membranes in presence and absence of cholesterol.

The effects of tricylic antidepressant clomipramine (CLO) on the membrane properties of saturated dimyristoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine as well as on unsaturated egg yolk phosphatidylcholine liposomes were investigated by the electron paramagnetic resonance spin-labeling technique, in combination with the simulation of the spectra, taking into account that the membrane is heterogeneous and composed of the regions with different fluidity characteristics. Different spin labels, monitoring membrane properties in the upper and inner parts of the membrane, were used. In general, two spectral components, having different motional characteristics, were detected in all liposomes investigated.

In vivo and ex vivo EPR detection of spin-labelled ovalbumin in mice.

In this study, spin-labelled ovalbumin (SL-OVA), free or entrapped in liposomes, was administered to mice subcutaneously (s.c.) or intravenously (i.

Systemic use of selective iNOS inhibitor 1400W or non-selective NOS inhibitor l-NAME differently affects systemic nitric oxide formation after oral Porphyromonas gingivalis inoculation in mice.

Objective: Nitric oxide synthase (NOS) inhibitors are reported to protect against the local tissue damage in gingivitis and periodontal disease by reducing nitroxidative stress during inflammation, but their systemic effects are not well investigated.

Design: NOS inhibitors systemic effects were investigated in a murine chronic oral inoculation model using live Porphyromonas gingivalis ATCC 33277 (0.3 ml; 10(9)cfu/ml) or sterile broth (0.

Effect of a topical vasodilator on tumor hypoxia and tumor oxygen guided radiotherapy using EPR oximetry.

We sought to reduce tumor hypoxia by topical application of a vasodilator, benzyl nicotinate (BN), and investigated its effect on the growth of tumors irradiated at times when tumor pO(2) increased. EPR oximetry was used to follow the changes in the tissue pO(2) of subcutaneous radiation-induced fibrosarcoma (RIF-1) tumors during topical applications of 1.25-8% BN formulations for 5 consecutive days.

Determination of the amount of micelles in alkylphospholipid liposome formulations with electron paramagnetic resonance method.

Alkylphospholipids (APLs) are physiologically active derivatives of lipids with high efficiency in the therapy of experimental human breast cancer. Therefore, they are usually used as liposome formulations, since the application of free, micellar APLs results in serious side effects, such as hemolysis. Since only rough upper estimates of micelle proportions were obtained until now, we developed a new method, based on the spectral decomposition of electron paramagnetic resonance (EPR) spectra.

EPR and FTIR studies reveal the importance of highly ordered sterol-enriched membrane domains for ostreolysin activity.

Ostreolysin is a cytolytic protein from the edible oyster mushroom (Pleurotus ostreatus), which recognizes specifically and binds to raft-like sterol-enriched membrane domains that exist in the liquid-ordered phase. Its binding can be abolished by micromolar concentrations of lysophospholipids and fatty acids. The membrane activity of ostreolysin, however, does not completely correlate with the ability of a certain sterol to induce the formation of a liquid-ordered phase, suggesting that the protein requires an additional structural organization of the membrane to exert its activity.

Impact of membrane properties on uptake and transcytosis of colloidal nanocarriers across an epithelial cell barrier model.

The aim of this study was to investigate the effect of liposomal membrane properties on cellular uptake and transcytosis across a tight Madin-Darby canine kidney (MDCK) cell barrier in vitro. More than 25 small vesicles were prepared by lipid film hydration/extrusion to generate small unilamellar vesicles. The fluorescence marker calcein was encapsulated to mimic hydrophilic drug transport.

Improvements of cellular stress response on resveratrol in liposomes.

Resveratrol (RSV) has proven potential in prophylaxis and treatment of various disorders mediated by free radicals and oxidative stress. RSV solubility, stability, and cytotoxicity must be regulated for satisfactory bioavailability. Here, RSV was loaded into liposomes, characterized by PCS and TEM and evaluated on HEK293 cell line by metabolic activity assay, electron paramagnetic resonance, and fluorescence microscopy.

Single oral inoculation with Escherichia coli (ATCC 25922) stimulates generalised production of nitric oxide in mice.

Nitric oxide (NO) production was investigated in the lungs, thoracic aorta, heart, liver, spleen, kidneys and brain of mice inoculated orally with Escherichia coli ATCC 25922. Detection of NO was performed by electron paramagnetic resonance (EPR) using diethyldithiocarbamate (DETC) spin trap. Nitric oxide synthase (NOS) inhibitors [nonselective: L-NAME and inducible NOS (iNOS) selective: 1400W] were used to determine the source of NO.

Chronic ingestion of Porphyromonas gingivalis induces systemic nitric oxide response in mice.

Introduction: Porphyromonas gingivalis induces nitric oxide (NO) production in various cells, systemic NO elevation being expected in chronic oral challenge.

Methods: Groups of BALB/c mice were inoculated orally with either live P. gingivalis ATCC 33277 or sterile broth on days 0, 2 and 4, with or without later administration of the inducible nitric oxide synthase (iNOS) inhibitor 1400W.

An ESR characterization of micelles and vesicles formed in aqueous decanoic acid/sodium decanoate systems using different spin labels.

Aqueous decanoic acid/sodium decanaote systems were studied as a function of pH and concentration, up to 0.3 M decanoic acid/sodium decanoate, by electron spin resonance (ESR) spectroscopy using three different amphiphilic spin labels. The distribution of the spin labels between vesicles and micelles as well as their dynamic properties were determined by quantitative analysis of the ESR spectra using two novel simulation software packages.