RESUMEN

Small angle X-ray scattering measurements under ambient conditions (T ≈ 294 K) provide evidence for the formation of separate domains in a ternary, mixed phospholipid ([DMPE]/[DMPC] = 3/1) / cholesterol model bilayer membrane. As we interpret these results, the domains contain cholesterol and DMPC, with which cholesterol is known to preferentially interact in a binary model membrane (solubility limit, mol fraction cholesterol 0.5), as compared to DMPE (solubility limit, mol fraction cholesterol 0.45). The solubility limit for the ternary system is mol fraction cholesterol 0.2-0.3. Although literature EPR spectra find that non-crystalline, cholesterol bilayer domains may be present even prior to the observation of cholesterol crystal diffraction, X-ray scattering cannot detect their presence.

Asunto(s)

Dimiristoilfosfatidilcolina , Membrana Dobles de Lípidos , Dimiristoilfosfatidilcolina/química , Membrana Dobles de Lípidos/química , Solubilidad , Rayos X , Colesterol/química , Difracción de Rayos X

RESUMEN

Background & Aims: Schistosomiasis is a parasitic infection which affects more than 200 million people globally. Schistosome eggs, but not the adult worms, are mainly responsible for schistosomiasis-specific morbidity in the liver. It is unclear if S. mansoni eggs consume host metabolites, and how this compromises the host parenchyma. Methods: Metabolic reprogramming was analyzed by matrix-assisted laser desorption/ionization mass spectrometry imaging, liquid chromatography with high-resolution mass spectrometry, metabolite quantification, confocal laser scanning microscopy, live cell imaging, quantitative real-time PCR, western blotting, assessment of DNA damage, and immunohistology in hamster models and functional experiments in human cell lines. Major results were validated in human biopsies. Results: The infection with S. mansoni provokes hepatic exhaustion of neutral lipids and glycogen. Furthermore, the distribution of distinct lipid species and the regulation of rate-limiting metabolic enzymes is disrupted in the liver of S. mansoni infected animals. Notably, eggs mobilize, incorporate, and store host lipids, while the associated metabolic reprogramming causes oxidative stress-induced DNA damage in hepatocytes. Administration of reactive oxygen species scavengers ameliorates these deleterious effects. Conclusions: Our findings indicate that S. mansoni eggs completely reprogram lipid and carbohydrate metabolism via soluble factors, which results in oxidative stress-induced cell damage in the host parenchyma. Impact and implications: The authors demonstrate that soluble egg products of the parasite S. mansoni induce hepatocellular reprogramming, causing metabolic exhaustion and a strong redox imbalance. Notably, eggs mobilize, incorporate, and store host lipids, while the metabolic reprogramming causes oxidative stress-induced DNA damage in hepatocytes, independent of the host's immune response. S. mansoni eggs take advantage of the host environment through metabolic reprogramming of hepatocytes and enterocytes. By inducing DNA damage, this neglected tropical disease might promote hepatocellular damage and thus influence international health efforts.

RESUMEN

The study introduces first report on a liquid chromatographic method for the quantification of 1,2-Dimyristoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] ammonium salt (DMPE-PEG 2000), which is an important constituent of lipid-based nanoparticles. It involves an HPLC-CAD stability-indicating assay method development for DMPE-PEG 2000 and structure elucidation of its degradation products. Hypersil Gold™ PFP column (150 mm × 4.6 mm, 3.0 µm) was used to achieve the separation among DMPE-PEG 2000 and its degradation products using 0.0025% formic acid in water: methanol (80:20 v/v) as mobile phase A and methanol: acetonitrile (60:40 v/v) as mobile phase B in a gradient elution mode. The method was validated for precision, linearity, sensitivity, solution stability and robustness. Relative standard deviations for the intra-day precision, inter-day precision and sensitivity were 1.6%, 0.6% and 3.8%, respectively. The method was linear in the range from 210 µg/mL to 390 µg/mL with R2 value of 0.996. Further, the solution stability of DMPE-PEG 2000 was evaluated under different stressed and storage conditions to understand the impact of any excursion to its regular storage temperature of -20 °C. The observed degradation products were identified through liquid chromatography high resolution mass spectrometry and a tentative pathway was proposed for the generation of these degradants.

Asunto(s)

Fosfolípidos , Polietilenglicoles , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Fosfatidiletanolaminas , Reproducibilidad de los Resultados

RESUMEN

BACKGROUND: Heart failure has become a global health problem with increasing incidences worldwide. Traditional pharmacological treatments can delay but cannot reverse the underlying disease processes. The clinical application of myocardial tissue engineering represents a promising strategy because it features cell-based replacement therapies that replace partially or fully damaged cardiac tissues with in vitro-generated tissue equivalents. However, the effectiveness of this therapy is limited by poor viability and differentiation of the grafted cells. This limitation could be overcome by rapidly increasing the numbers of functional cardiomyocytes. In this study, we aimed to obtain functional myocardial tissue engineering seed cells with high proliferation and differentiation rates by combining 1,2-dimyristoyl-sn-glycero-3-phosphoethan-olamine-polyethylene glycol (DMPE-PEG) and recombinant transforming growth factor-ß1 receptor I (rTGF-ß1 RI), followed by binding to human adipose-derived stromal cells (hADSCs). METHODS: To induce higher expression level of TGF-ß1 RI, DMPE-PEG was inoculated with rTGF-ß1 RI to modify the surface of hADSCs. The differentiation ability and morphological characteristics of the modified hADSCs were examined in vitro and in vivo. RESULTS: The caridiomyocartic differentiation ability of TGF-ß1 RI-modified hADSCs was significantly enhanced, as indicated by elevated expression levels of the cardiac markers cardiac troponin T (cTnT) and α-smooth muscle actin (SMA) via increased phosphorylation of the Smad signaling pathway-related proteins. CONCLUSION: Our findings provide new insights into stem cell transplantation therapy in myocardial tissue engineering.

Asunto(s)

Tejido Adiposo/metabolismo , Células Madre Mesenquimatosas/metabolismo , Fosfatidiletanolaminas/metabolismo , Factor de Crecimiento Transformador beta1/genética , Tejido Adiposo/citología , Diferenciación Celular , Humanos , Factor de Crecimiento Transformador beta1/metabolismo

RESUMEN

Polyhedral oligomeric silsesquioxanes (POSS) derivatives have been receiving remarkable attention due to their potential biomedical application and therefore understanding molecular mechanism of their interaction with cell membranes should be studied at molecular level. Here we investigate the binary mixture of an open silsesquioxane cage POSS-poly(ethylene glycol) (POSS-PEG) and 1,2-myristoyl-sn-glycero-3-phosphoethanolamine (DMPE) as a representative of phospholipid located in biological membranes. The surface pressure-area and surface potential-area compression isotherms, as well as Brewster angle microscopy and interfacial shear rheology were used to study monolayers at the air/water interface. The results show that POSS-PEG exhibits an insoluble monolayer with side group chains anchored to the air/water interface. The outcomes of the conducted experiments show (i) the evidence of a stable incorporation of POSS molecule to the DMPE monolayer modifying its equilibrium and dynamic properties and (ii) squeezing the POSS-polymer out of the lipid monolayer at a higher molecular packing density. The results from the conducted experiments together with thermodynamic analysis suggest area condensation and mutual miscibility at the surface pressure relevant to a real biological membrane.

Asunto(s)

Aire , Compuestos de Organosilicio/química , Fosfolípidos/química , Polietilenglicoles/química , Agua/química , Modelos Moleculares , Estructura Molecular , Tamaño de la Partícula , Propiedades de Superficie

RESUMEN

We report a new polydiacetylene (PDA) sensor strip for simple visual detection of zinc ions in aqueous solution. The specificity of this sensor comes from Zn2+ DNA aptamer probes conjugated onto PDA. Effects of aptamer length and structure on the sensitivity of PDA's color transition were first investigated. PDA conjugated with the optimal aptamer sequence was then coated onto a strip of polyvinylidene fluoride membrane and photopolymerized by UV exposure. The newly developed sensor successfully exhibited a blue-to-red chromatic change in a semi-quantitative manner in response to zinc ions. No discernable change was observed in solutions containing other common ions. Advantages of this sensor include its ease of fabrication, high specificity, and equipment-free detection, all of which are desirable for in-field applications and use in resource-limited settings.

RESUMEN

Efficient gene therapy is mainly dependent on the gene transfer capability of gene delivery vectors. Non-viral vectors have become the research interest of many researchers because these vectors are safer than viral vectors. Acquiring the advantages of both polyplexes and lipoplexes, the lipopolyplex (LPP) is a ternary nanocomplex composed of cationic liposome, polycation, and nucleic acid. Considering the polycationic component, ternary complexes (LPPs) are divided into cationic polymer-based LPPs and cationic peptide-based LPPs. Considering the capability of rational design, LPP is an interesting field of research to design a more potent nucleic acid carrier. With the promising transfection activity and safety observed in the LPPs, many researchers have formulated various types of lipids and polycations to achieve an efficient and safe carrier for gene therapy. Here we provide a review on the designed LPPs for efficient delivery of different nucleic acids such as plasmid DNA, siRNA, shRNA, and DNA vaccines.

Asunto(s)

Técnicas de Transferencia de Gen , Liposomas/química , Nanopartículas/química , Ácidos Nucleicos/química , Animales , Química Farmacéutica , Terapia Genética/métodos , Humanos , Lípidos/química , Péptidos/química , Polímeros/química , Transfección

RESUMEN

Cardiolipins (CLs) are important biologically for their unique role in biomembranes that couple phosphorylation and electron transport like bacterial plasma membranes, chromatophores, chloroplasts and mitochondria. CLs are often tightly coupled to proteins involved in oxidative phosphorylation. The first step in understanding the interaction of CL with proteins is to obtain the pure CL structure, and the structure of mixtures of CL with other lipids. In this work we use a variety of techniques to characterize the fluid phase structure, material properties and thermodynamics of mixtures of dimyristoylphosphatidylcholine (DMPC) with tetramyristoylcardiolipin (TMCL), both with 14-carbon chains, at several mole percentages. X-ray diffuse scattering was used to determine structure, including bilayer thickness and area/lipid, the bending modulus, KC, and SXray, a measure of chain orientational order. Our results reveal that TMCL thickens DMPC bilayers at all mole percentages, with a total increase of ∼6 Å in pure TMCL, and increases AL from 64 Å(2) (DMPC at 35 °C) to 109 Å(2) (TMCL at 50 °C). KC increases by ∼50%, indicating that TMCL stiffens DMPC membranes. TMCL also orders DMPC chains by a factor of ∼2 for pure TMCL. Coarse grain molecular dynamics simulations confirm the experimental thickening of 2 Å for 20mol% TMCL and locate the TMCL headgroups near the glycerol-carbonyl region of DMPC; i.e., they are sequestered below the DMPC phosphocholine headgroup. Our results suggest that TMCL plays a role similar to cholesterol in that it thickens and stiffens DMPC membranes, orders chains, and is positioned under the umbrella of the PC headgroup. CL may be necessary for hydrophobic matching to inner mitochondrial membrane proteins. Differential scanning calorimetry, SXray and CGMD simulations all suggest that TMCL does not form domains within the DMPC bilayers. We also determined the gel phase structure of TMCL, which surprisingly displays diffuse X-ray scattering, like a fluid phase lipid. AL=40.8 Å(2) for the ½TMCL gel phase, smaller than the DMPC gel phase with AL=47.2 Å(2), but similar to AL of DLPE=41 Å(2), consistent with untilted chains in gel phase TMCL.

Asunto(s)

Cardiolipinas/química , Dimiristoilfosfatidilcolina/química , Membrana Dobles de Lípidos/química , Simulación de Dinámica Molecular , Rastreo Diferencial de Calorimetría , Cristalografía por Rayos X , Dimiristoilfosfatidilcolina/metabolismo , Geles/química , Membrana Dobles de Lípidos/metabolismo , Conformación Molecular , Termodinámica , Temperatura de Transición

RESUMEN

The functional effects of a drug ligand may be due not only to an interaction with its membrane protein target, but also with the surrounding lipid membrane. We have investigated the interaction of a drug ligand, PK11195, with its primary protein target, the integral membrane 18kDa translocator protein (TSPO), and model membranes using Langmuir monolayers, quartz crystal microbalance with dissipation monitoring (QCM-D) and neutron reflectometry (NR). We found that PK11195 is incorporated into lipid monolayers and lipid bilayers, causing a decrease in lipid area/molecule and an increase in lipid bilayer rigidity. NR revealed that PK11195 is incorporated into the lipid chain region at a volume fraction of ~10%. We reconstituted isolated mouse TSPO into a lipid bilayer and studied its interaction with PK11195 using QCM-D, which revealed a larger than expected frequency response and indicated a possible conformational change of the protein. NR measurements revealed a TSPO surface coverage of 23% when immobilised to a modified surface via its polyhistidine tag, and a thickness of 51Å for the TSPO layer. These techniques allowed us to probe both the interaction of TSPO with PK11195, and PK11195 with model membranes. It is possible that previously reported TSPO-independent effects of PK11195 are due to incorporation into the lipid bilayer and alteration of its physical properties. There are also implications for the variable binding profiles observed for TSPO ligands, as drug-membrane interactions may contribute to the apparent affinity of TSPO ligands.

Asunto(s)

Isoquinolinas/metabolismo , Membrana Dobles de Lípidos/metabolismo , Lípidos de la Membrana/metabolismo , Receptores de GABA/metabolismo , Animales , Liposomas , Ratones , Transporte de Proteínas , Tecnicas de Microbalanza del Cristal de Cuarzo

RESUMEN

Hyaluronan synthase (HAS) is a unique membrane-associated glycosyltransferase and its activity is lipid dependent. The dependence however is not well understood, especially in vertebrate systems. Here we investigated the functional association of hyaluronan synthesis in a cholesterol-rich membrane-environment. The culture of human dermal fibroblasts in lipoprotein-depleted medium attenuated the synthesis of hyaluronan. The sequestration of cellular cholesterol by methyl-ß-cyclodextrin also decreased the hyaluronan production of fibroblasts, as well as the HAS activity. To directly evaluate the effects of cholesterol on HAS activity, a recombinant human HAS2 protein with a histidine-tag was expressed as a membrane protein by using a baculovirus system, then successfully solubilized, and isolated by affinity chromatography. When the recombinant HAS2 proteins were reconstituted into liposomes composed of both saturated phosphatidylcholine and cholesterol, this provided a higher enzyme activity as compared with the liposomes formed by phosphatidylcholine alone. Cholesterol regulates HAS2 activity in a biphasic manner, depending on the molar ratio of phosphatidylcholine to cholesterol. Furthermore, the activation profiles of different lipid compositions were determined in the presence or absence of cholesterol. Cholesterol had the opposite effect on the HAS2 activity in liposomes composed of phosphatidylethanolamine or phosphatidylserine. Taken together, the present data suggests a clear functional association between HAS activity and cholesterol-dependent alterations in the physical and chemical properties of cell membranes.

Asunto(s)

Colesterol/metabolismo , Fibroblastos/metabolismo , Glucuronosiltransferasa/metabolismo , Ácido Hialurónico/biosíntesis , Metabolismo de los Lípidos/fisiología , Células Cultivadas , Activación Enzimática , Glucuronosiltransferasa/química , Humanos , Hialuronano Sintasas

RESUMEN

The fusion peptide of Ebola virus comprises a highly hydrophobic sequence located downstream from the N-terminus of the glycoprotein GP2 responsible for virus-host membrane fusion. The internal fusion peptide of GP2 inserts into membranes of infected cell to mediate the viral and the host cell membrane fusion. Since the sequence length of Ebola fusion peptide is still not clear, we study in the present work the behavior of two fusion peptides of different lengths which were named EBO17 and EBO24 referring to their amino acid length. The secondary structure and orientation of both peptides in lipid model systems made of DMPC:DMPG:cholesterol:DMPE (6:2:5:3) were investigated using PMIRRAS and polarized ATR spectroscopy coupled with Brewster angle microscopy. The infrared results showed a structural flexibility of both fusion peptides which are able to transit reversibly from an α-helix to antiparallel ß-sheets. Ellipsometry results corroborate together with isotherm measurements that EBO peptides interacting with lipid monolayer highly affected the lipid organization. When interacting with a single lipid bilayer, at low peptide content, EBO peptides insert as mostly α-helices mainly perpendicular into the lipid membrane thus tend to organize the lipid acyl chains. Inserted in multilamellar vesicles at higher peptide content, EBO peptides are mostly in ß-sheet structures and induce a disorganization of the lipid chain order. In this paper, we show that the secondary structure of the Ebola fusion peptide is reversibly flexible between α-helical and ß-sheet conformations, this feature being dependent on its concentration in lipids, eventually inducing membrane fusion.

Asunto(s)

Ebolavirus/química , Membrana Dobles de Lípidos/química , Oligopéptidos/química , Proteínas Virales de Fusión/química , Secuencia de Aminoácidos , Colesterol/química , Dimiristoilfosfatidilcolina/química , Interacciones Hidrofóbicas e Hidrofílicas , Fusión de Membrana , Microscopía , Datos de Secuencia Molecular , Fosfatidiletanolaminas/química , Fosfatidilgliceroles/química , Estructura Secundaria de Proteína , Espectrofotometría Infrarroja

RESUMEN

This report presents evidence that the following Solanum steroids: solasodine, diosgenin and solanine interact with human erythrocytes and molecular models of their membranes as follows: a) X-ray diffraction studies showed that the compounds at low molar ratios (0.1-10.0mol%) induced increasing structural perturbation to dimyristoylphosphatidylcholine bilayers and to a considerable lower extent to those of dimyristoylphosphatidylethanolamine; b) differential scanning calorimetry data showed that the compounds were able to alter the cooperativity of dimyristoylphosphatidylcholine, dimyristoylphosphatidylethanolamine and dimyristoylphosphatidylserine phase transitions in a concentration-dependent manner; c) in the presence of steroids, the fluorescence of Merocyanine 540 incorporated to the membranes decreased suggesting a fluidization of the lipid system; d) scanning electron microscopy observations showed that all steroids altered the normal shape of human erythrocytes inducing mainly echinocytosis, characterized by the formation of blebs in their surfaces, an indication that their molecules are located into the outer monolayer of the erythrocyte membrane.

Asunto(s)

Diosgenina/química , Membrana Eritrocítica/química , Membrana Dobles de Lípidos/química , Alcaloides Solanáceos/química , Solanina/química , Rastreo Diferencial de Calorimetría , Dimiristoilfosfatidilcolina/química , Diosgenina/farmacología , Membrana Eritrocítica/efectos de los fármacos , Colorantes Fluorescentes/química , Humanos , Microscopía Electrónica de Rastreo , Transición de Fase/efectos de los fármacos , Fosfatidiletanolaminas/química , Fosfatidilserinas/química , Pirimidinonas/química , Dispersión del Ángulo Pequeño , Alcaloides Solanáceos/farmacología , Solanina/farmacología , Difracción de Rayos X

RESUMEN

This work analyzes the surface properties of PE-containing membranes modified at the head group region by the addition of methyl and ethyl residues at or near the amine group. These residues alter the lipid-lipid and lipid-water interactions by changes in the hydrogen bonding capability and the charge density of the amine group thus affecting the electrostatic interaction. The results obtained by measuring the dipole potential, the zeta potential, the area per lipid and the compressibility properties allow to conclude that the H-bonding capability prevails in the lipid-lipid interaction. The non polar groups attached to the C2-carbon of the ethanolamine chain introduces a steric hindrance against compression and increases the dipole potential. The analysis of areas suggests that lipids with methylated head groups have a much larger compressibility at expense of the elimination of hydration water, which is congruent with the broader extent of the hysteresis loop.

Asunto(s)

Fosfatidiletanolaminas/química , Dimiristoilfosfatidilcolina/química , Etanolamina/química , Enlace de Hidrógeno , Agua/química

RESUMEN

A unique organelle for studying membrane biochemistry is the mitochondrion whose functionality depends on a coordinated supply of proteins and lipids. Mitochondria are capable of synthesizing several lipids autonomously such as phosphatidylglycerol, cardiolipin and in part phosphatidylethanolamine, phosphatidic acid and CDP-diacylglycerol. Other mitochondrial membrane lipids such as phosphatidylcholine, phosphatidylserine, phosphatidylinositol, sterols and sphingolipids have to be imported. The mitochondrial lipid composition, the biosynthesis and the import of mitochondrial lipids as well as the regulation of these processes will be main issues of this review article. Furthermore, interactions of lipids and mitochondrial proteins which are highly important for various mitochondrial processes will be discussed. Malfunction or loss of enzymes involved in mitochondrial phospholipid biosynthesis lead to dysfunction of cell respiration, affect the assembly and stability of the mitochondrial protein import machinery and cause abnormal mitochondrial morphology or even lethality. Molecular aspects of these processes as well as diseases related to defects in the formation of mitochondrial membranes will be described.

Asunto(s)

Lípidos/química , Mitocondrias/química , Mitocondrias/metabolismo , Membranas Mitocondriales/química , Membranas Mitocondriales/metabolismo , Plantas/metabolismo , Saccharomyces cerevisiae/metabolismo

RESUMEN

Lipid-polymer hybrid nanoparticles (LPNs) are core-shell nanoparticle structures comprising polymer cores and lipid/lipid-PEG shells, which exhibit complementary characteristics of both polymeric nanoparticles and liposomes, particularly in terms of their physical stability and biocompatibility. Significantly, the LPNs have recently been demonstrated to exhibit superior in vivo cellular delivery efficacy compared to that obtained from polymeric nanoparticles and liposomes. Since their inception, the LPNs have advanced significantly in terms of their preparation strategy and scope of applications. Their preparation strategy has undergone a shift from the conceptually simple two-step method, involving preformed polymeric nanoparticles and lipid vesicles, to the more principally complex, yet easier to perform, one-step method, relying on simultaneous self-assembly of the lipid and polymer, which has resulted in better products and higher production throughput. The scope of LPNs' applications has also been extended beyond single drug delivery for anticancer therapy, to include combinatorial and active targeted drug deliveries, and deliveries of genetic materials, vaccines, and diagnostic imaging agents. This review details the current state of development for the LPNs preparation and applications from which we identify future research works needed to bring the LPNs closer to its clinical realization.

Asunto(s)

Sistemas de Liberación de Medicamentos , Lípidos/química , Nanopartículas , Polímeros/química , Animales , Estabilidad de Medicamentos , Ensayos Analíticos de Alto Rendimiento/métodos , Humanos , Liposomas , Polietilenglicoles/química

RESUMEN

Pyrazole compounds are an intriguing class of compounds with potential analgesic activity; however, their mechanism of action remains unknown. Thus, the goal of this study was to explore the antinociceptive potential, safety and mechanism of action of novel 1-pyrazole methyl ester derivatives, which were designed by molecular simplification, using in vivo and in vitro methods in mice. First, tree 1-pyrazole methyl ester derivatives (DMPE, MPFE, and MPCIE) were tested in the capsaicin test and all presented antinociceptive effect; however the MPClE (methyl 5-trichloromethyl-3-methyl-1H-pyrazole-1-carboxylate) was the most effective. Thus, we selected this compound to assess the effects and mechanisms in subsequent pain models. MPCIE produced antinociception when administered by oral, intraperitoneal, intrathecal and intraplantar routes and was effective in the capsaicin and the acetic acid-induced nociception tests. Moreover, this compound reduced the hyperalgesia in diverse clinically-relevant pain models, including postoperative, inflammatory, and neuropathic nociception in mice. The antinociception produced by orally administered MPClE was mediated by κ-opioid receptors, since these effects were prevented by systemically pre-treatment with naloxone and the κ-opioid receptor antagonist nor-binaltorphimine. Moreover, MPCIE prevented binding of the κ-opioid ligand [(3)H]-CI-977 in vitro (IC50 of 0.68 (0.32-1.4) µM), but not the TRPV1 ([(3)H]-resiniferatoxin) or the α2-adrenoreceptor ([(3)H]-idazoxan) binding. Regarding the drug-induced side effects, oral administration of MPClE did not produce sedation, constipation or motor impairment at its active dose. In addition, MPCIE was readily absorbed after oral administration. Taken together, these results demonstrate that MPClE is a novel, potent, orally active and safe analgesic drug that targets κ-opioid receptors.

Asunto(s)

Analgésicos/farmacología , Pirazoles/farmacología , Receptores Opioides kappa/agonistas , Antagonistas de Receptores Adrenérgicos alfa 2 , Analgésicos/administración & dosificación , Analgésicos/antagonistas & inhibidores , Analgésicos/química , Animales , Benzofuranos , Diterpenos , Vías de Administración de Medicamentos , Evaluación Preclínica de Medicamentos , Idazoxan , Masculino , Ratones , Estructura Molecular , Naloxona/farmacología , Naltrexona/análogos & derivados , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Dimensión del Dolor , Pirazoles/administración & dosificación , Pirazoles/antagonistas & inhibidores , Pirazoles/química , Pirrolidinas , Ensayo de Unión Radioligante , Receptores Opioides kappa/antagonistas & inhibidores , Canales Catiónicos TRPV/efectos de los fármacos , Tritio

RESUMEN

A measurement of (2)H spin-lattice relaxation time, T(1), forD(2)O was performed with a high resolution liquid NMR apparatus fortwo samples of dimyristoylphosphatidylethanolamine (DMPE)-D(2)Osystem in a full hydration at varying temperatures of -20, -10, and 5 (°)C, and both components and compositions of differently boundfreezable water molecules were estimated from a best-fitted curve toexperimental inversion recovery data. A choice of the best-fitted curve wasbased on a distribution of weighted residuals for the experimental data. Asingle component was found for a temperature of -20 (°)C. At 5 (°)C, where all the freezable water exists in the liquid state, threecomponents were observed to be characterized by T(1) values ofapproximately 20, 100, and 200 ms, respectively. By comparingcompositions of these individual components with those obtained in ourprevious DSC study, it was revealed that the first and secondarycomponents are members of freezable interlamellar water and the last oneis comparable to bulk water.