Magnetic Resonance Characterization Research Articles

Cecropin B loaded TiO2 nanotubes coated with hyaluronidase sensitive multilayers for reducing bacterial adhesion

Bacterial infection, a common issue related to orthopedic implantation, is regarded as the second dominant factor resulting in implantation failure. To address the issue, the study reports a novel antibacterial titanium substrate against hyaluronidase secreting bacterium of Staphylococcus aureus, which was fabricated by employing TiO2 nanotubes (TNTs) to load cecropin B (CecB), and then coating with hyaluronidase sensitive multilayers of chitosan/sodium hyaluronic-cecropin B [(Chi/SH–CecB)5] onto the titanium surfaces via layer by layer technique (TNT–CecB–LBLc). Fourier transform infrared spectroscopy (FITR) and nuclear magnetic resonance (1H NMR) characterizations proved the successful synthesis of SH–CecB. Scanning electron microscopy (SEM), atomic force microscopy (AFM), fluorescence microscopy and water contact angle measurements verified the formation of multilayers onto CecB loaded titanium substrates. The presence of S. aureus and/or exogenous hyaluronidase effectively triggered the degradation of multilayers, thus facilitating the release of CecB from TNTs. The antibacterial evaluations proved that TNT–CecB–LBLc substrates had good early (4h) and long term (72h) antibactericidal capacity against both S. aureus and Staphylococcus epidermidis. Moreover, the cellular tests displayed that TNT–CecB–LBLc substrates had relatively good cytocompatibility for osteoblasts, even co-culture with S. aureus. The study provides new insight into the development of bacteria-mediated antibacterial implants for orthopedic application.

Databases of Conformations and NMR Structures of Glycan Determinants.

The present study reports a comprehensive nuclear magnetic resonance (NMR) characterization and a systematic conformational sampling of the conformational preferences of 170 glycan moieties of glycosphingolipids as produced in large-scale quantities by bacterial fermentation. These glycans span across a variety of families including the blood group antigens (A, B and O), core structures (Types 1, 2 and 4), fucosylated oligosaccharides (core and lacto-series), sialylated oligosaccharides (Types 1 and 2), Lewis antigens, GPI-anchors and globosides. A complementary set of about 100 glycan determinants occurring in glycoproteins and glycosaminoglycans has also been structurally characterized using molecular mechanics-based computation. The experimental and computational data generated are organized in two relational databases that can be queried by the user through a user-friendly search engine. The NMR ((1)H and (13)C, COSY, TOCSY, HMQC, HMBC correlation) spectra and 3D structures are available for visualization and download in commonly used structure formats. Emphasis has been given to the use of a common nomenclature for the structural encoding of the carbohydrates and each glycan molecule is described by four different types of representations in order to cope with the different usages in chemistry and biology. These web-based databases were developed with non-proprietary software and are open access for the scientific community available at http://glyco3d.cermav.cnrs.fr.

A swine model of infarct-related reentrant ventricular tachycardia: Electroanatomic, magnetic resonance, and histopathological characterization

Human ventricular tachycardia (VT) after myocardial infarction usually occurs because of subendocardial reentrant circuits originating in scar tissue that borders surviving myocardial bundles. Several preclinical large animal models have been used to further study postinfarct reentrant VT, but with varied experimental methodologies and limited evaluation of the underlying substrate or induced arrhythmia mechanism. We aimed to develop and characterize a swine model of scar-related reentrant VT. Thirty-five Yorkshire swine underwent 180-minute occlusion of the left anterior descending coronary artery. Thirty-one animals (89%) survived the 6-8-week survival period. These animals underwent cardiac magnetic resonance imaging followed by electrophysiology study, detailed electroanatomic mapping, and histopathological analysis. Left ventricular (LV) ejection fraction measured using CMR imaging was 36% ± 6.6% with anteroseptal wall motion abnormality and late gadolinium enhancement across 12.5% ± 4.1% of the LV surface area. Low voltage measured using endocardial electroanatomic mapping encompassed 11.1% ± 3.5% of the LV surface area (bipolar voltage ≤1.5 mV) with anterior, anteroseptal, and anterolateral involvement. Reentrant circuits mapped were largely determined by functional rather than fix anatomical barriers, consistent with "pseudo-block" due to anisotropic conduction. Sustained monomorphic VT was induced in 28 of 31 swine (90%) (67 VTs; 2.4 ± 1.1; range 1-4) and characterized as reentry. VT circuits were subendocardial, with an arrhythmogenic substrate characterized by transmural anterior scar with varying degrees of fibrosis and myocardial fiber disarray on the septal and lateral borders. This is a well-characterized swine model of scar-related subendocardial reentrant VT. This model can serve as the basis for further investigation in the physiology and therapeutics of humanlike postinfarction reentrant VT.

Efficient Energy Transfer and Enhanced Near‐IR Emission in Cu+/Nd3+‐Activated Aluminophosphate Glass

The development of photonic materials for efficient energy conversion and high‐power solid‐state lasers is currently pursued given the wide range of applicable technologies and the possibility to help meet global energy demands in laser fusion power plants. In this work, Cu+ ions successfully incorporated in aluminophosphate glass are recognized as near‐ultraviolet (UV) sensitizers of Nd3+ ions resulting in remarkable near‐infrared (IR) 4F3/2 → 4I11/2 emission at 1.06 μm. Optical absorption, solid‐state 31P nuclear magnetic resonance, Raman, and photoluminescence spectroscopies characterizations are employed and assessment methods for material optical and structural properties are proposed. The spectroscopic data indicates an efficient (>50%) nonradiative energy transfer where the Cu+ ions first absorb photons broadly around 360 nm, and subsequently transfer the energy from the Stokes‐shifted emitting states to resonant Nd3+ energy levels. Then, the Nd3+ electronic excited states decay and the upper lasing state 4F3/2 is populated, leading to enhanced near‐IR emission. It is suggested that the physico‐chemically robust Cu+/Nd3+ codoped aluminophosphate glass is a suitable candidate as solid‐state laser material with enhanced pump range in the near‐UV part of the spectrum and for solar spectral conversion in photovoltaic cells.

Muscular Adaptations and Novel Magnetic Resonance Characterizations of Spinal Cord Injury

The spinal cord is highly complex, consisting of a specialized neural network that comprised both neuronal and non-neuronal cells. Any kind of injury and/or insult to the spinal cord leads to a series of damaging events resulting in motor and/or sensory deficits below the level of injury. As a result, muscle paralysis (or paresis) leading to muscle atrophy or shrinking of the muscle along with changes in muscle fiber type, and contractile properties have been observed. Traditionally, histology had been used as a gold standard to characterize spinal cord injury (SCI)-induced adaptation in spinal cord and skeletal muscle. However, histology measurements is invasive and cannot be used for longitudinal analysis. Therefore, the use of conventional magnetic resonance imaging (MRI) is promoted to be used as an alternative non-invasive method, which allows the repeated measurements over time and secures the safety against radiation by using radiofrequency pulse. Currently, many of pathological changes and adaptations occurring after SCI can be measured by MRI methods, specifically 3-dimensional MRI with the advanced diffusion tensor imaging technique. Both techniques have shown to be sensitive in measuring morphological and structural changes in skeletal muscle and the spinal cord.

Solid State NMR Characterization of Sn-Beta Zeolites that Catalyze Glucose Isomerization and Epimerization

High resolution, multi-nuclear solid state nuclear magnetic resonance (NMR) characterizations are carried out in order to obtain insights into the structural features of Sn-beta zeolites that catalyze glucose isomerization or epimerization reactions in water and methanol solvents. In particular, we focus on investigating the local structural changes to catalytically-active framework Sn sites of different ^(119)Sn-labeled beta zeolites, including the calcined, dehydrated, rehydrated, and post-sugar isomerization catalysis forms. Magic angle spinning (MAS) and cross polarization MAS (either from ^1H or ^(19)F) ^(119)Sn NMR spectra provide evidence for changes to the local framework Sn coordination in the presence of water and sugar molecules, and provide insights into structural features of adsorbed intermediates that may be relevant in sugar isomerization reaction pathways.

Tricin, a flavonoid monomer in monocot lignification.

Tricin was recently discovered in lignin preparations from wheat (Triticum aestivum) straw and subsequently in all monocot samples examined. To provide proof that tricin is involved in lignification and establish the mechanism by which it incorporates into the lignin polymer, the 4'-O-β-coupling products of tricin with the monolignols (p-coumaryl, coniferyl, and sinapyl alcohols) were synthesized along with the trimer that would result from its 4'-O-β-coupling with sinapyl alcohol and then coniferyl alcohol. Tricin was also found to cross couple with monolignols to form tricin-(4'-O-β)-linked dimers in biomimetic oxidations using peroxidase/hydrogen peroxide or silver (I) oxide. Nuclear magnetic resonance characterization of gel permeation chromatography-fractionated acetylated maize (Zea mays) lignin revealed that the tricin moieties are found in even the highest molecular weight fractions, ether linked to lignin units, demonstrating that tricin is indeed incorporated into the lignin polymer. These findings suggest that tricin is fully compatible with lignification reactions, is an authentic lignin monomer, and, because it can only start a lignin chain, functions as a nucleation site for lignification in monocots. This initiation role helps resolve a long-standing dilemma that monocot lignin chains do not appear to be initiated by monolignol homodehydrodimerization as they are in dicots that have similar syringyl-guaiacyl compositions. The term flavonolignin is recommended for the racemic oligomers and polymers of monolignols that start from tricin (or incorporate other flavonoids) in the cell wall, in analogy with the existing term flavonolignan that is used for the low-molecular mass compounds composed of flavonoid and lignan moieties.

Escherichia coli auxotroph host strains for amino acid-selective isotope labeling of recombinant proteins.

Enrichment of proteins with isotopes such as (2)H, (15)N, and (13)C is commonly carried out in magnetic resonance and vibrational spectroscopic characterization of protein structures, mechanisms, and dynamics. Although uniform isotopic labeling of proteins is straightforward, efficient labeling of proteins with only a selected set of amino acid types is often challenging. A number of approaches have been described in the literature for amino acid-selective isotope labeling of proteins, each with its own limitations. Since Escherichia coli represents the most cost-effective and widely used host for heterologous production of foreign proteins, an efficient method to express proteins selectively labeled with isotopes would be highly valuable for these studies. However, an obvious drawback is misincorporation and dilution of input isotope labels to unwanted amino acid types due to metabolic scrambling in vivo. To overcome this problem, we have generated E. coli auxotroph strains that are compatible with the widely used T7 RNA polymerase overexpression systems and that minimize metabolic scrambling. We present several examples of selective amino acid isotope labeling of simple and complex proteins with bound cofactors, as an initial guide for practical applications of these E. coli strains.

Insoluble protein characterization by circular dichroism (CD) spectroscopy and nuclear magnetic resonance (NMR).

Besides misfolded proteins, which still retain the capacity to fold into uniquely defined structures but are misled to "off-pathway" aggregation, there exists a group of proteins which are unrefoldable and insoluble in buffers. Previously no general method was available to solubilize them and consequently their solution conformations could not be characterized. Recently, we discovered that these insoluble proteins could in fact be solubilized in pure water. Circular dichroism (CD) spectroscopy and nuclear magnetic resonance (NMR) characterization led to their classification into three groups, all of which lack the tight tertiary packing and consequently anticipated to unavoidably aggregate in vivo with ~150 mM ions, thus designated as "intrinsically insoluble proteins (IIPs)." It appears that eukaryotic genomes contain many "IIP," which also have a potential to interact with membranes to trigger neurodegenerative diseases. In this chapter, we provide a detailed procedure to express and purify these proteins, followed by CD and NMR spectroscopy characterization of their conformation and interaction with dodecylphosphocholine (DPC).

Cardiovascular magnetic resonance characterization of left ventricular non-compaction provides independent prognostic information in patients with incident heart failure or suspected cardiomyopathy.

BackgroundWith recent advances in imaging methods, detection of LVNC is increasingly common. Concomitantly, the prognostic importance of LVNC is less clear.MethodsWe followed 42 patients (63% male, age 44 ± 15 years) with incident heart failure or suspected cardiomyopathy, in whom cardiovascular magnetic resonance (CMR) yielded a diagnosis of LVNC, for 27 ± 16 months.ResultsLVNC was preferentially distributed among posterolateral segments, with apical predominance. Patients with maximum non-compacted-to-compacted thickness ratio (NC:C) < 3 improved by 0.9 ± 0.7 NYHA Class, compared to 0.3 ± 0.8 for patients with NC:C > 3 (p = 0.001). In 29 patients with baseline LVEF < 0.40, there was an inverse correlation between NC:C ratio, and the change in LVEF during follow-up. Tachyarrhythmias were observed in 42% of patients with LGE, and in 0% of patients without LGE (p = 0.02). In multivariate analysis, arrhythmia incidence was significantly higher in patients with LGE, even when adjusted for LVEF and RVEF.ConclusionsCMR assessments of myocardial morphology provide important prognostic information for patients with LVNC who present with incident heart failure or suspected cardiomyopathy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-014-0064-2) contains supplementary material, which is available to authorized users.

Preparation of Novel Biocompatible Macromolecular Magnetic Resonance Imaging Contrast Agent

Abstract Poly (aspartic acid-co-leucine) (PL) synthesized with aspartic acid and leucine was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) by ethylenediamine. Then the compound obtained was chelated with gadolinium (III) to form PL-A 2 -DOTA-Gd. The structure of PL-A 2 -DOTA-Gd was characterized by nuclear magnetic resonance and gel chromatography and its performance was evaluated by cytotoxicity test, heamolysis test, in vitro relaxivity determination and animal in vivo magnetic resonance characterization. PL-A 2 -DOTA-Gd exhibited much lower cytotoxicity than Gd-DOTA. The T1-relaxivity of PL-A 2 -DOTA-Gd (15.3 mM −1 s −1 ) was 2.6 times than that of Gd-DOTA (5.8 mM −1 s −1 ) in D 2 O. The results of magnetic resonance imaging (MRI) experiments showed a significant enhancement in the rat liver imaging after the intravenous administration of PL-A 2 -DOTA-Gd. In addition, the imaging time persisted by using PL-A 2 -DOTA-Gd than that of Gd-DOTA and the imaging effect of liver tissue was enhanced by an average of 65.1% ± 5.2% and 21.3% ± 4.9% for PL-A 2 -DOTA-Gd and Gd-DOTA, respectively.

C4H8SO3Hmim]HSO4 as an efficient catalyst for direct liquefaction of bagasse lignin: Decomposition properties of the inner structural units

Catalytic valorization of renewable aromatic lignin is attracting increasing attention. In this study, an efficient method for direct liquefaction of sugarcane bagasse lignin using acidic ionic liquid (IL) 1-(4-sulfobutyl)-3-methyl imidazolium hydrosulfate ([C4H8SO3Hmim]HSO4) is presented. The relationships between catalyst dosage, reaction condition parameters and degree of liquefaction, and the structure and elemental composition of liquefaction residue were investigated. The transformation performances of three molecular structural units (guaiacyl, syringyl, and hydroxyphenyl units) of bagasse lignin were also intensively examined using gas chromatography-mass spectrometry, elemental analysis, Fourier transform infrared spectrometry, and proton nuclear magnetic resonance characterization. The results demonstrated that the dual-functionalized acidic IL exhibited excellent catalytic performance in the direct liquefaction process. More than 65% degree of liquefaction was achieved under optimized conditions, yielding 13.5% of useful aromatic fine chemicals such as phenol, 4-ethylphenol, and guaiacol. The p-hydroxyphenyl unit of lignin was the most flexible, followed by the guaiacyl unit, whereas the syringyl group was the most refractory. Furthermore, the catalytic mechanism was proposed.

Magnetic resonance characterization of septal bounce: findings of blood impact physiology.

'Septal bounce' is a pathognomonic sign of constrictive pericarditis (CP). The objectives of the study are to resolve the etiology of the septal bounce, to generate septal bounce-related diagnostic tools, and to prove that its presence is related to the mechanical interaction between the atrioventricular inflow and the inter-ventricular septum. We compared steady state free precession four-chamber images between 11 CP patients and 11 controls via cardiac magnetic resonance. The septal bounce was composed of two movements observed during every cardiac cycle, simultaneous with the rapid filling and atrial systole respectively. Three parameters (measured at end-systole) were generated: right ventricular (RV) clamp (compression ratio of the RV)-greater in CP (0.88±0.03) than controls (0.85±0.03, p=0.02), tri-septal angle between the tricuspid valve annulus plane and the interventricular septum (81°±9° vs. 91°±7°, p=0.01), and impact angle between the tricuspid inflow vector and septum (8.6°±8.7° vs. 0°±6.6°, p=0.01). The accuracy, positive predictive value, sensitivity and specificity of these parameters in differentiating CP from controls ranged from 100 to 82%. A forth parameter-septal flow ratio, gauging the proportion of tricuspid inflow impacting the septum, was markedly higher in CP than controls (0.38±0.19 vs. 0.01±0.03, p<0.0001) with 100% sensitivity, specificity, positive and negative predictive value. The septal bounce consists of two sequential movements during each cardiac cycle, is time-related with the rapid ventricular filling and atrial systole, and likely represents a result of the tricuspid blood inflow impacting the interventricular septum. Four septal bounce-derived parameters have a good accuracy in differentiating CP from volunteers.

Crystallographic and spectroscopic insights into heme degradation by Mycobacterium tuberculosis MhuD.

Mycobacterium heme utilization degrader (MhuD) is a heme-degrading protein from Mycobacterium tuberculosis responsible for extracting the essential nutrient iron from host-derived heme. MhuD has been previously shown to produce unique organic products compared to those of canonical heme oxygenases (HOs) as well as those of the IsdG/I heme-degrading enzymes from Staphylococcus aureus. Here, we report the X-ray crystal structure of cyanide-inhibited MhuD (MhuD–heme–CN) as well as detailed 1H nuclear magnetic resonance (NMR), UV/vis absorption, and magnetic circular dichroism (MCD) spectroscopic characterization of this species. There is no evidence for an ordered network of water molecules on the distal side of the heme substrate in the X-ray crystal structure, as was previously reported for canonical HOs. The degree of heme ruffling in the crystal structure of MhuD is greater than that observed for HO and less than that observed for IsdI. As a consequence, the Fe 3dxz-, 3dyz-, and 3dxy-based MOs are very close in energy, and the room-temperature 1H NMR spectrum of MhuD–heme–CN is consistent with population of both a 2Eg electronic state with a (dxy)2(dxz,dyz)3 electron configuration, similar to the ground state of canonical HOs, and a 2B2g state with a (dxz,dyz)4(dxy)1 electron configuration, similar to the ground state of cyanide-inhibited IsdI. Variable temperature, variable field MCD saturation magnetization data establishes that MhuD–heme–CN has a 2B2g electronic ground state with a low-lying 2Eg excited state. Our crystallographic and spectroscopic data suggest that there are both structural and electronic contributions to the α-meso regioselectivity of MhuD-catalyzed heme cleavage. The structural distortion of the heme substrate observed in the X-ray crystal structure of MhuD–heme–CN is likely to favor cleavage at the α- and γ-meso carbons, whereas the spin density distribution may favor selective oxygenation of the α-meso carbon.

Nuclear magnetic resonance characterization of shallow marine sediments from the Nankai Trough, Integrated Ocean Drilling Program Expedition 333

AbstractWe measured nuclear magnetic resonance (NMR) relaxation times on samples from Integrated Ocean Drilling Program Expedition 333 Sites C0011, C0012, and C0018. We compared our results to permeability, grain size, and specific surface measurements, pore size distributions from mercury injection capillary pressure, and mineralogy from X‐ray fluorescence. We found that permeability could be predicted from NMR measurements by including grain size and specific surface to quantify pore networks and that grain size is the most important factor in relating NMR response to permeability. Samples within zones of anomalously high porosity from Sites C0011 and C0012 were found to have different NMR‐permeability relationships than samples from outside these zones, suggesting that the porosity anomaly is related to a fundamental difference in pore structure. We additionally estimated the size of paramagnetic sites that cause proton relaxation and found that in most of our samples, paramagnetic material is present mainly as discrete, clay‐sized grains. This distribution of paramagnetic material may cause pronounced heterogeneity in NMR properties at the pore scale that is not accounted for in most NMR interpretation techniques. Our results provide important insight into the microstructure of marine sediments in the Nankai Trough.

Usefulness of MRI in takotsubo cardiomyopathy: a review of the literature.

Takotsubo cardiomyopathy (TC) is a disease that can be misinterpreted as a more serious acute coronary syndrome. Its clinical characteristics resemble those of a myocardial infarct, while its imaging characteristics are critical on correctly characterizing and diagnosing the disease. From angiography, where coronary anatomy is evaluated, to cardiac magnetic resonance (CMR), where morphology and tissue characterization is assessed, the array of imaging options is quite extent. In particular, CMR has achieved great improvements (stronger magnetic fields, better coils, etc.) in the last decade which in turn has made this imaging technology more attractive in the evaluation and diagnosis of TC. With its superior soft tissue resolution and dynamic imaging capabilities, CMR is currently, perhaps, the most useful imaging technique in TC as apical ballooning or medio-basal wall motion abnormalities (WMA), presence of wall edema and late gadolinium enhancement (LGE) characteristics are critical in the diagnosis and characterization of this pathology. In this review, CMRs role in TC will be evaluated in light of the current available evidence in medical literature, while also revising the clinical and physiopathologic characteristics of TC.

Interzeolite conversion of zeolite MCM-49 into zeolite ZSM-35 in cyclohexylamine–hexamethyleneimine–Na2O–H2O containing systems

The interzeolite conversion of zeolite MCM-49 into zeolite ZSM-35 in “cyclohexylamine (CHA)–hexamethyleneimine (HMI)–Na2O–H2O” systems, consisting of “CHA–Na2O–H2O”, “HMI–Na2O–H2O” and “Na2O–H2O”, was investigated in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) characterization techniques. Both CHA and HMI play important roles in directing the interzeolite conversion of MCM-49 into ZSM-35, and the conversion speed is much faster in systems containing CHA than those containing HMI. Even in the Na2O–H2O system without any organic amine, MCM-49 can still transform into some other zeolites with more stable topological structures than itself, such as ZSM-35, ZSM-5, and mordenite, but the product of the interzeolite conversion is more complicated than that in the systems containing organic amines (CHA and/or HMI). In the Na2O–H2O system, alkalinity has been proved to be a crucial factor influencing the conversion trend of MCM-49. Zeolites ZSM-5 and mordenite will appear in the products besides ZSM-35 with the increase of the alkalinity. The conversion process of zeolite MCM-49 in the systems investigated accords well with the solution-mediated transformation mechanism.

Magnetic resonance characterization of tissue engineered cartilage via changes in relaxation times, diffusion coefficient, and shear modulus.

The primary goal of this paper is to describe a combined MR relaxation (T(2) and T(1ρ)), diffusion (apparent diffusion coefficient [ADC]), and elastography (shear stiffness) method of fully characterizing the development of tissue-engineered cartilage in terms of the changes in its composition, structure, and mechanical properties during tissue growth. Then, we may better use MR-based methodologies to noninvasively monitor and optimize the cartilage tissue engineering process without sacrificing the constructs. This process begins by demonstrating the potential capability of T(2), T(1ρ), ADC, and shear stiffness in characterizing a scaffold-free engineered cartilage. The results show that, in addition to the conventional T(2) and ADC, T(1ρ) and MRE can be used as potential biomarkers to assess the specific changes in proteoglycan content and mechanical properties of engineered cartilage during culture. Moreover, to increase the efficiency of MR characterization, two new methodologies for simultaneous acquisition of diffusion and MRE (dMRE), and T(1ρ) and MRE (T(1ρ)-MRE) are introduced that allow the simultaneous characterization of both biochemical and mechanical properties of engineered cartilage tissue. The feasibilities of dMRE and T(1ρ)-MRE approaches are validated on tissue-mimicking phantoms. The results show good correspondence between simultaneous acquisitions and conventional separate acquisition methods.

Juliprosopine and Juliprosine from Prosopis juliflora Leaves Induce Mitochondrial Damage and Cytoplasmic Vacuolation on Cocultured Glial Cells and Neurons

Prosopis juliflora is a shrub largely used for animal and human consumption. However, ingestion has been shown to induce intoxication in animals, which is characterized by neuromuscular alterations induced by mechanisms that are not yet well understood. In this study, we investigated the cytotoxicity of a total alkaloid extract (TAE) and one alkaloid fraction (F32) obtained from P. juliflora leaves to rat cortical neurons and glial cells. Nuclear magnetic resonance characterization of F32 showed that this fraction is composed of a mixture of two piperidine alkaloids, juliprosopine (majority constituent) and juliprosine. TAE and F32 at concentrations between 0.3 and 45 μg/mL were tested for 24 h on neuron/glial cell primary cocultures. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test revealed that TAE and F32 were cytotoxic to cocultures, and their IC50 values were 31.07 and 7.362 μg/mL, respectively. Exposure to a subtoxic concentration of TAE or F32 (0.3-3 μg/mL) induced vacuolation and disruption of the astrocyte monolayer and neurite network, ultrastructural changes, characterized by formation of double-membrane vacuoles, and mitochondrial damage, associated with changes in β-tubulin III and glial fibrillary acidic protein expression. Microglial proliferation was also observed in cultures exposed to TAE or F32, with increasing levels of OX-42-positive cells. Considering that F32 was more cytotoxic than TAE and that F32 reproduced in vitro the main morphologic and ultrastructural changes of "cara torta" disease, we can also suggest that piperidine alkaloids juliprosopine and juliprosine are primarily responsible for the neurotoxic damage observed in animals after they have consumed the plant.

Multi-dimensional Nuclear Magnetic Resonance Characterizations of Dynamics and Saturations of Brine/Crude Oil/Mud Filtrate Mixtures Confined in Rocks: The Role of Asphaltene

We propose multi-dimensional one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques for probing quantitatively the different saturations and dynamics of brine/crude oil/mud filtrate mixtures confined in a rock system that could be used potentially down-hole. The rock samples and petroleum fluids have been characterized by standard petrophysical techniques. Electron spin resonance (ESR) quantitatively measured levels of the paramagnetic vanadyl ions VO2+ and organic radicals trapped in the used crude oils with and without asphaltene. Size-exclusion microchromatography with a high-resolution inductively coupled plasma–mass spectrometric detection technique has demonstrated the trapping of metalloporphyrine (MP) by asphaltene nanoaggregates. These two latter techniques have shown that around 2/3 of VO2+ is trapped in MP embedded within asphaltene nanoaggregates, while 1/3 stayed in the bulk. Standard gas chromatography (GC) and gel permeation chromatography (GPC) have exten...