Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir-Blodgett/Langmuir-Schaefer Technique

Bent-core liquid crystals, a class of mesogenic compounds with non-linear molecular structures, are well known for their unconventional mesophases, characterized by complex molecular (and supramolecular) ordering and often featuring biaxial and polar properties. In the nematic phase, their unique behavior is manifested in the formation of nano-sized biaxial clusters of layered molecules (cybotactic groups). While this prompted their consideration in the quest for nematic biaxiality, experimental evidence indicates that the cybotactic order is only short-ranged and that the nematic phase is macroscopically uniaxial. By combining atomic force microscopy, neutron reflectivity and wide-angle grazing-incidence X-ray scattering, here, we demonstrate that multilayer films of a bent-core nematic, deposited on silicon by a combined Langmuir-Blodgett and Langmuir-Schaefer approach, exhibit macroscopic in-plane ordering, with the long molecular axis tilted with respect to the sample surface and the short molecular axis (i.e., the apex bisector) aligned along the film compression direction. We thus propose the use of Langmuir films as an effective way to study and control the complex anchoring properties of bent-core liquid crystals.

The influence of mannose-based esters on the mesophase behaviour of lyotropic liquid crystalline nanosystems as drug delivery vectors

Lyotropic Liquid Crystalline (LLC) nanoparticles represent an emerging class of smart, biocompatible, and biodegradable systems for the delivery of drugs. Among these, structures with complex 3D architectures such as cubosomes are of particular interest. These are non- lamellar assemblies having hydrophobic and hydrophilic portions able to carry drugs of different nature. They can further be modulated including suitable additives to control the release of the active payload, and to promote an active targeting. Starting from monoolein (GMO) cubic phase, different concentrations of mannose-based esters were added, and the eventual structural modifications were monitored to ascertain the effects of the presence of glycolipids. Moreover, the structural properties of these nanosystems loaded with Dexamethasone (DEX), a very well-known anti-inflammatory steroid, were also studied. Experiments were carried out by synchrotron Small Angle X-ray Scattering (SAXS), Raman Microspectroscopy (RMS) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) measurements. The drug delivery potential (i.e. entrapment efficiency and release properties) of the obtained nanoparticles was evaluated. Finally, in vitro cytocompatibility and anti-inflammatory activity studies of the prepared formulations were carried out. Inclusion of mannose-based surfactants up to 10 mol% influenced the structural parameters of Im3m cubic phase and swollen cubic phases were obtained with the different glycolipids with lattice parameters significantly higher than GMO. A complete cytocompatibility and an increased DEX activity were observed, thus suggesting the possibility to use GMO/glycolipids nanoparticles to formulate innovative drug delivery systems.

Characterisation of Bee Pollen from the Marche Region (Italy) According to the Botanical and Geographical Origin with Analysis of Antioxidant Activity and Colour, Using a Chemometric Approach

Attempts have often been made to isolate and characterise monofloral pollens to correlate nutritional with botanical properties. Nevertheless, pollen harvested in a particular area that can have a high biodiversity could have healthier properties. In addition, the analysis of the pollen's botanical composition can be important for characterising the typical flora of a specific geographical area. On this basis, various pollens collected in different locations of the Marche region (Italy) and in different harvesting periods were analyzed for botanical composition and antioxidant (total phenolic content, ABTS, DPPH and ORAC tests), granulometry and colour (CIE L*a*b*) properties to evaluate the biodiversity of pollen sources within a particular geographical area and to correlate this to the nutraceutical characteristics. Antioxidant activity results showed values generally higher than those of monofloral pollens harvested in the same areas but manually separated according to colour, shape and size. This suggests that even the floral species present in low percentages may have an influence on the nutraceutical properties of these products. The multivariate statistical elaboration of the obtained results permitted the separation of samples containing a prevalent botanical species and the grouping of all the samples into separate clusters corresponding to different areas of Marche.

A vibrational in vitro approach to evaluate the potential of monoolein nanoparticles as isofuranodiene carrier in MDA-MB 231 breast cancer cell line: New insights from Infrared and Raman microspectroscopies

Isofuranodiene (IFD) is a sesquiterpene occurring in several plant species, which proved to have multiple anticancer activities. IFD has a lipophilic nature and, hence, a very low water solubility and a poor bioavailability; moreover, it is not stable, undergoing the "Cope rearrangement" to the less active curzerene. The use of appropriate delivery systems can thus be considered as a valid tool to enhance IFD bioavailability, solubility, stability and at the same time also to improve its intracellular uptake and pharmacological activity. Within this frame, monoolein (GMO) nanoparticles loaded with IFD were prepared and their enhanced anticancer activity, compared to pristine IFD, was assessed. In this study, for the first time, an in vitro Fourier Transform Infrared and Raman Microspectroscopy approaches were exploited to evaluate the effects of IFD, alone and loaded in GMO nanoparticles, on MDA-MB 231 breast cancer cell line. The anti-cancer effects of IFD were evidenced by both the spectroscopic techniques and discriminated from the GMO-induced changes in the culture environment; moreover, a synergistic effect of IFD and GMO administration can be envisaged by the experimental results.

Cubic and Hexagonal Mesophases for Protein Encapsulation: Structural Effects of Insulin Confinement

Monoolein-based cubic and hexagonal mesophases were investigated as matrices for insulin loading, at low pH, as a function of temperature and in the presence of increasing amounts of oleic acid, as a structural stabilizer for the hexagonal phase. Synchrotron small angle X-ray diffraction, rheological measurements, and attenuated total reflection-Fourier transform infrared spectroscopy were used to study the effects of insulin loading on the lipid mesophases and of the effect of protein confinement in the 2D- and 3D-lipid matrix water channels on its stability and unfolding behavior. We found that insulin encapsulation has only little effects both on the mesophase structures and on the viscoelastic properties of lipid systems, whereas protein confinement affects the response of the secondary structure of insulin to thermal changes in a different manner according to the specific mesophase: in the cubic structure, the unfolding toward an unordered structure is favored, while the prevalence of parallel β-sheets, and nuclei for fibril formation, is observed in hexagonal structures.

Acute toxic exposures in children: analysis of a three year registry managed by a Pediatric poison control Center in Italy

Introduction

Acute pediatric poisoning is an emerging health and social problem. The aim of this study is to describe the characteristics of a large pediatric cohort exposed to xenobiotics, through the analysis of a Pediatric Poison Control Center (PPCc) registry.

Methods

This study, conducted in the Pediatric Hospital Bambino Gesù of Rome, a reference National Pediatric Hospital, collected data of children whose parents or caregivers contacted the PPCc by phone (group “P”), or who presented to the Emergency Department (group “ED”), during the three-year period 2014–2016. Data were prospectively and systematically collected in a pre-set electronic registry. Comparisons among age groups were performed and multivariable logistic regression models used to investigate associations with outcomes (hospital referral for “P”, and hospital admission for “ED”group).

Results

We collected data of 1611 children on group P and 1075 on group ED. Both groups were exposed to both pharmaceutical and non-pharmaceutical agents. Pharmaceutical agent exposure increased with age and the most common route of exposure was oral. Only 10% among P group were symptomatic children, with gastrointestinal symptoms. Among the ED patients, 30% were symptomatic children mostly with gastrointestinal (55.4%) and neurologic symptoms (23.8%). Intentional exposure (abuse substance and suicide attempt), which involved 7.7% of patients, was associated with older age and Hospital admission.

Conclusions

Our study describes the characteristics of xenobiotics exposures in different paediatric age groups, highlighting the impact of both pharmacological and intentional exposure. Furthermore, our study shows the utility of a specific PPCc, either through Phone support or by direct access to ED. PPCc phone counselling could avoid unnecessary access to the ED, a relevant achievement, particularly in the time of a pandemic.

Nanostructure of Unconventional Liquid Crystals Investigated by Synchrotron Radiation

The macroscopic properties of novel liquid crystal (LC) systems-LCs with unconventional molecular structure as well as conventional LCs in unconventional geometries-directly descend from their mesoscopic structural organization. While X-ray diffraction (XRD) is an obvious choice to investigate their nanoscale structure, conventional diffractometry is often hampered by experimental difficulties: the low scattering power and short-range positional order of the materials, resulting in weak and diffuse diffraction features; the need to perform measurements in challenging conditions, e.g., under magnetic and/or electric fields, on thin films, or at high temperatures; and the necessity to probe micron-sized volumes to tell the local structural properties from their macroscopic average. Synchrotron XRD allows these problems to be circumvented thanks to the superior diffraction capabilities (brilliance, q-range, energy and space resolution) and advanced sample environment available at synchrotron beamlines. Here, we highlight the potentiality of synchrotron XRD in the field of LCs by reviewing a selection of experiments on three unconventional LC systems: the potentially biaxial and polar nematic phase of bent-core mesogens; the very high-temperature nematic phase of all-aromatic LCs; and polymer-dispersed liquid crystals. In all these cases, synchrotron XRD unveils subtle nanostructural features that are reflected into macroscopic properties of great interest from both fundamental and technological points of view.

Nanostructured liquid crystalline particles as delivery vectors for isofuranodiene: Characterization and in-vitro anticancer activity

Isofuranodiene is an oxygenated sesquiterpene containing a furan ring isolated from the essential oil of Smyrnium olusatrum L. (Apiaceae) owning notable anticancer activity. Despite its biological potential, the high lipophilicity along with a relatively low stability due to Cope rearrangement giving rise to a less active compound, make the perspective of its therapeutical use unlikely. On this basis, in the present work we evaluated bulk and dispersed non lamellar liquid crystalline phases as effective delivery vectors for isofuranodiene, and capable of preserving its structure and enhancing the biological activity. Small-angle X-ray scattering, dynamic light scattering, and UV resonance Raman spectroscopy were used to characterize the nanosystems in an integrated experimental approach. Encapsulation of isofuranodiene in the lipid matrix resulted in a transition from a cubic Im3m to a reversed hexagonal phase because of the highly lipophilic character of the drug, as obtained in SAXS measurements, and in significant shifts in the components of the Raman spectrum of isofuranodiene. The anticancer activity of isofuranodiene-loaded lipidic nanoparticles was assessed on MDA-MB 231 cell line by MTT assay and was found to be higher than that of pristine isofuranodiene.

Investigation of human pancreatic cancer tissues by Fourier Transform Infrared Hyperspectral Imaging

Fourier-transform infrared hyperspectral imaging (FTIR-HSI) provides hyperspectral images containing both morphological and chemical information. It is widely applied in the biomedical field to detect tumor lesions, even at the early stage, by identifying specific spectral biomarkers. Pancreatic neoplasms present different prognoses and are not always easily classified by conventional analyses. In this study, tissue samples with diagnosis of pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumor were analyzed by FTIR-HSI and the spectral data compared with those from healthy and dysplastic samples. Multivariate/univariate approaches were complemented to hyperspectral images, and definite spectral markers of the different lesions identified. The malignant lesions were recognizable both from healthy/dysplastic pancreatic tissues (high values of phospholipids and triglycerides with shorter, more branched and less unsaturated alkyl chains) and between each other (different amounts of total lipids, phosphates and carbohydrates). These findings highlight different metabolic pathways characterizing the different samples, well detectable by FTIR-HSI.

Encapsulation of vitamin B12 into nanoengineered capsules and soft matter nanosystems for targeted delivery

Targeted delivery of vitamins to a desirable area is an active branch in a modern pharmacology. The most important and difficult delivery of vitamin B₁₂ is that to bone marrow and nerve cells. Herein we present a first step towards the development of two types of smart carriers, polymer capsules and lyotropic liquid-crystalline nanosystems, for vitamin B₁₂ targeted delivery and induced release. A vitamin B₁₂ encapsulation technique into nanoengineered polymeric capsules produced by layer-by-layer assembling of polymeric shells on CaCO₃ templates has been developed. The effectiveness of the process was demonstrated by optical absorption spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and small-angle X-ray diffraction. TEM and AFM analyses performed on capsules after their drying, confirmed the presence of the vitamin B₁₂ inside the capsules in the form of crystalline nanoaggregates, 50-300 nm in diameter. Soft lipid nanovectors consisting of amphiphilic phytantriol molecules, which in water excess spontaneously self-assembly in 3D well-ordered inverse bicontinuous cubic bulk phase, were used as alternative carriers for vitamin B₁₂. It was shown that about 30% of the vitamin added in the preparation of the soft lipid system was actually encapsulated in cubosomes and that no structural changes occurred upon loading. The Vitamin stabilizes the lipid system playing the role of its structure-forming element. The biocompatible nature, the stability and the feasibility of these systems make them good candidates as carriers for hydrophilic vitamins.

Correction: Liponitroxides: EPR study and their efficacy as antioxidants in lipid membranes

Correction for ‘Liponitroxides: EPR study and their efficacy as antioxidants in lipid membranes’ by Giovanna Mobbili et al., RSC Adv., 2015, 5, 98955–98966.

Lyotropic Liquid-Crystalline Nanosystems as Drug Delivery Agents for 5-Fluorouracil: Structure and Cytotoxicity

Lyotropic cubic liquid-crystalline systems have received increasing attention due to their unique microstructural and physicochemical properties as efficient nanocarriers for drug delivery. We report the preparation and characterization of bulk phases and cubosome dispersions of phytantriol loaded with the anticancer drug 5-fluorouracil, in neutral and anionic forms. In both cases, a Pn3m cubic phase was observed. The phytantriol phase behavior can be influenced by the addition of ionic agents, and, to this purpose, a positively charged lipid, such as N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride salt (DOTAP), was included in the studied formulations. It was found to induce a variation of the spontaneous membrane curvature of the phytantriol lipid bilayer, generating a transition from the Pn3m to the Im3m cubic phase. When 5-fluorouracil, in its anionic form (5-FUs), was encapsulated in these latter systems, a further transition to the H_II hexagonal phase was observed as a consequence of the formation of a complex phytantriol/DOTAP/5-FUs. The physicochemical characterization was performed with various complementary techniques including synchrotron small-angle X-ray scattering, dynamic light scattering, and attenuated total reflection Fourier transform infrared and UV resonance Raman spectroscopies. Encapsulation of 5-fluorouracil in the corresponding nanodispersions was evaluated, and their in vitro cytotoxicity was assessed in MDA-MB-231 cell line. Phytantriol cubosomes containing 5-fluorouracil showed a higher toxicity compared with the bare drug solution, and hence they represent potential nanocarriers in the delivery of 5-fluorouracil for cancer therapy.

Selective induction of apoptosis in MCF7 cancer-cell by targeted liposomes functionalised with mannose-6-phosphate

Liposomes are versatile platforms to carry anticancer drugs in targeted drug delivery; they can be surface modified by different strategies and, when coupled with targeting ligands, are able to increase cellular internalisation and organelle-specific drug delivery. An interesting strategy of antitumoral therapy could involve the use of lysosomotropic ligand-targeted liposomes loaded with molecules, which can induce lysosomal membrane permeabilization (LMP), leakage of cathepsins into the cytoplasm and subsequent apoptosis. We have previously demonstrated the ability of liposomes functionalised with a mannose-6-phosphate to reach lysosomes; in this research we compare the behaviour of M6P-modified and non-functionalised liposomes in MCF7 tumour cell and in HDF normal cells. With this aim, we first demonstrated by Western blotting the overexpression of mannose-6-phosphate/insulin-like growth factor (M6P/IGF-II) receptor in MCF7. Then, we prepared calcein-loaded liposomes and we revealed the increased uptake of M6P-functionalised liposomes in MCF7 cells respect to HDF cells by flow cytometry analysis. Finally, we loaded functionalised and not functionalised liposomes with N-hexanoyl-d-erythro-sphingosine (C6Cer), able to initiate LMP-induced apoptosis; after having studied the stability of both vesicles in the presence of serum by Dynamic Light Scattering and Spectrophotometric turbidity measurements, we showed that ceramide-loaded M6P-liposomes significantly increased apoptosis in MCF7 with respect to HDF cells.

Comparing clinical outcomes in HIV-infected and uninfected older men hospitalized with community-acquired pneumonia

OBJECTIVES

Outcomes of community-acquired pneumonia (CAP) among HIV-infected older adults are unclear.

METHODS

Associations between HIV infection and three CAP outcomes (30-day mortality, readmission within 30 days post-discharge, and hospital length of stay [LOS]) were examined in the Veterans Aging Cohort Study (VACS) of male Veterans, age ≥ 50 years, hospitalized for CAP from 10/1/2002 through 08/31/2010. Associations between the VACS Index and CAP outcomes were assessed in multivariable models.

RESULTS

Among 117 557 Veterans (36 922 HIV-infected and 80 635 uninfected), 1203 met our eligibility criteria. The 30-day mortality rate was 5.3%, the mean LOS was 7.3 days, and 13.2% were readmitted within 30 days of discharge. In unadjusted analyses, there were no significant differences between HIV-infected and uninfected participants regarding the three CAP outcomes (P > 0.2). A higher VACS Index was associated with increased 30-day mortality, readmission, and LOS in both HIV-infected and uninfected groups. Generic organ system components of the VACS Index were associated with adverse CAP outcomes; HIV-specific components were not. Among HIV-infected participants, those not on antiretroviral therapy (ART) had a higher 30-day mortality (HR 2.94 [95% CI 1.51, 5.72]; P = 0.002) and a longer LOS (slope 2.69 days [95% CI 0.65, 4.73]; P = 0.008), after accounting for VACS Index. Readmission was not associated with ART use (OR 1.12 [95% CI 0.62, 2.00] P = 0.714).

CONCLUSION

Among HIV-infected and uninfected older adults hospitalized for CAP, organ system components of the VACS Index were associated with adverse CAP outcomes. Among HIV-infected individuals, ART was associated with decreased 30-day mortality and LOS.

Liponitroxides: EPR study and their efficacy as antioxidants in lipid membranes

Fighting lipid peroxidation on its own ground: the antioxidant activity of new synthesized lipid-functionalized nitroxides is maximized in the PUFA region and correlates with the nitroxide location within the lipid bilayer as found by EPR spectroscopy.

Liposome-based gene delivery systems containing a steroid derivative: computational and small angle X-ray diffraction study

The structural properties and the phase behaviour of mixed composition liposomes containing a functionalized lipid are investigated with the aim to design neutral liposomes able to coordinate metals and to complex DNA.

Antitoxin use and pediatric intensive care for viper bites in Rome, Italy

In Italy viper bites represent an uncommon event, though envenomation can cause severe complications, more in children than adults, because of dose/body size ratio. We present a case series within a selected population: 10 Italian cases (from Rome surroundings) of viperbites requiring PICU admission, over a 5-year interval. Five children showed a systemic involvement, whereas the remaining patients showed a damage. All were managed and closely monitored in an ICU setting. Relevant clinical findings and therapeutic approach, ICU course and complications have been recorded. Age range was 3-15 years with mean age of 6,9 (SD±4,58) years; 2 patients needed respiratory support beyond oxygen supplementation. Most patients underwent fluid loading, while hemodynamic support was given to4/10. Median PICU stay was 60 hours (IQR=24.0-75.5). No mortality was reported. Indications and precautions for administration of antivenom in the last years have been reviewed: early treatment seems to reduce mortality/morbidity, though representing a threat for children. Current recommendations for the treatment of viper envenomation have been described, based on a literature's review and the application of these knowledges to clinical reality of our PICUs. Therefore, paediatric patients with systemic or rapidly evolving symptoms should be monitored carefully for the development of bite-related complications in an ICU setting mostly in younger children.

Liposomes containing mannose-6-phosphate-cholesteryl conjugates for lysosome-specific delivery

We present a novel liposomal nanocarrier containing mannose 6-phosphate-cholesteryl conjugates and show its ability to reach the lysosomes by means of confocal and fluorescence microscopy measurements.

Exposure assessment of mycotoxins in cow's milk in Argentina

A stochastic simulation model was developed to carry out the first quantitative risk exposure assessment of the mycotoxin level in cow's milk produced in Argentina. The prevalence and concentration of aflatoxin M1 (AFM1), deoxynivalenol (DON) and zearalenone (ZEA) were modeled at various stages through milk processes complying with Argentinean practices. Concentration of AFM1 (0.059ppb), DON (0.338ppb) and ZEA (0.125ppb) in dairy milk were estimated. The proportion of feed samples that exceeded the maximum level accepted by European regulations for AFB1, DON and ZEA were estimated at 25.07%, 0.0% and 8.9%, respectively. The percentage of milk samples that exceeded the maximum level accepted for AFB1 by the MERCOSUR (0.5ppb) and the European Union regulations (0.05ppb) were 0.81 and 32.65, respectively. The probability distribution of AFM1 concentration in milk was affected by the carry-over rate equations applied in the model. Mycotoxin levels in corn silage and concentrated feeds were the factors most correlated with mycotoxin concentrations in milk. Therefore, agricultural practices, crop management and feed production require prompt attention regarding mycotoxin issues.

Elevated serum ALT in children presenting to the emergency unit: Relationship with NAFLD

BACKGROUND

Non-alcoholic fatty liver disease, ranging from hepatic steatosis to necro-inflammation with or without fibrosis (non-alcoholic steatohepatitis), is a growing clinical liver disorder in children.

AIM

The goals of this study were to characterize liver disorders associated with elevated aminotransferases and establish the non-alcoholic fatty liver disease/non-alcoholic steatohepatitis prevalence in hypertransaminasemic children admitted to the emergency room.

METHODS

The medical records of 3280 children (2-17 years of age) admitted to the emergency room of Bambino Gesù Children's Hospital of Rome, and presenting with hypertransaminasemia were analysed retrospectively.

RESULTS

Elevation of serum alanine aminotransferases was present in 897 patients. Of these, 520 (58%) spontaneously normalized alanine aminotransferases, and 179/897 (20%) maintained persistently elevated alanine aminotransferases levels. Twenty-one patients were excluded because of medication or alcohol use. In the remaining 157 patients with elevated alanine aminotransferases, obesity was found in 87 (55%), viral infections in 52 (33%) and genetic diseases in 14 (9%). Obesity-related alanine aminotransferases elevation was associated with a histological diagnosis of non-alcoholic fatty liver disease in 85% of patients. In particular, steatosis was histologically confirmed in 74 patients; 43/74 (58%) had steatohepatitis, and 12/74 (16%) had fibrosis.

CONCLUSIONS

Twenty percent of children with elevated aminotransferases on routine testing may hide non-alcoholic fatty liver disease/non-alcoholic steatohepatitis. A careful diagnostic workup of persistent hypertransaminasemia in all obese subjects is warranted in the paediatric setting.

Effects on platelet function of combination etoposide and carboplatin chemotherapy in pediatric oncology patients

The effects of a therapeutic course of the combination of carboplatin and etoposide on platelet function have been evaluated in 10 pediatric patients with brain tumors. Platelet count, in vitro aggregation tests, P-selectin expression and agonist-induced ATP release were evaluated before, and 7 and 15 days after one cycle of chemotherapy. The analysis of the results demonstrated the presence of an in vitro platelet aggregation defect in response to collagen and arachidonic acid in all patients 7 days after therapy. A concomitant decrease of collagen- and arachidonic acid-induced ATP release was also observed. Both platelet aggregation and ATP release returned to baseline values 15 days after chemotherapy administration. Conversely, in vitro platelet aggregation and secretion induced by ADP and epinephrine were unaltered by carboplatin and etoposide administration. Furthermore, P-selectin expression was negative at baseline and did not change after chemotherapy. These results support the hypothesis that combination etoposide and carboplatin chemotherapy in pediatric patients is responsible for possible disturbances in biochemical pathways required for platelet secretion and aggregation.

Nanoaggregates of copper porphyrazine in floating layers and Langmuir-Schaefer films

Aggregation behavior of unsubstituted copper porphyrazine (CuPaz) on the water surface was studied by analysis of compression curves, Brewster angle microscopy (BAM), and optical spectroscopy. The structure and stability of the CuPaz aqua aggregates in the floating layers are determined by hydration degree that depends on initial surface concentration and surface pressure. Langmuir-Schaefer (LS) films of CuPaz were prepared by deposition of the variously structured floating layers and studied by X-ray scattering technique and optical spectroscopy. Stable and labile structures were detected and compared with the floating CuPaz aqua aggregates. Conditions of formation of the stable four-stacked nanoaggregates in LS films were determined. A model comprising both nucleation of CuPaz on the water surface and structural transformations in the solid films is proposed.

Metal cation induced cubic phase in poly(ethylene glycol)-functionalized dioleoylphosphatidylethanolamine aqueous dispersions

Metal cations (Mn(2+) or Ca(2+)) in aqueous dispersions of mixtures of dioleoylphosphatidylethanolamine (DOPE) and poly(ethylene glycol)-functionalized DOPE (DOPE-PEG(350)) induce, above a certain amount of the PEG lipid component, a phase transition from the inverted hexagonal phase H(II) to the bicontinuous inverted cubic phase Q(224) with space group Pn3m. The process is driven by the decrease of free elastic energy due to the Gaussian curvature of the cubic phase. The structural characterization of the phase behavior over the whole explored range of DOPE-PEG/DOPE weight ratio (3-25%) is reported, focusing on the role of the metal cation in the formation of the 3D cubic lattice. This result may represent a significant progress toward a design-based approach to drug delivery.

Pressure effects on lipidic direct phases: the dodecyl trimethyl ammonium chloride-water system

The direct lyotropic polymorphism of dodecyltrimethylammonium chloride (DTAC) was investigated by synchrotron X-ray diffraction at different water concentrations under compression up to 2 kbar, i.e., in the pressure intermediate range where interesting biophysical transformations occur and the functional characteristics of cell membranes are altered. The results show that pressure induces the transition from the hexagonal phase to the micellar Pm3n cubic phase in hydrated samples (c between 0.5 and 0.6, c being the weight concentration of lipid in the mixture) and the transition from the bicontinuous Ia3d cubic phase to the hexagonal phase in drier samples (c = 0.8). By increasing the pressure on very dry samples, a lamellar L(alpha) phase was observed to form transitorily at the Ia3d cubic-hexagonal phase transition. Phase compressibility and then the lipid and water partial molecular compressibilities were derived as a function of pressure and concentration. As a result, we assessed the very low compressibility of the hydration water within the lipid phases, and we demonstrated that the compressibility of DTAC is very dependent on pressure. Moreover, the molecular parameters of DTAC calculated in the different phases during compression confirmed that pressure induces small but continuous conformational changes, definitely different from the large changes observed in lipid molecules forming type II structures.

Structure and Phase Behavior of Self-Assembled DPPC−DNA−Metal Cation Complexes

Multilamellar liposomes of dipalmitoylphosphatidylcholine (DPPC) in solution with DNA and bivalent metal cations (Ca2+, Mn2+, Mg2+) self-assemble into a ternary DPPC-DNA-Me2+ complex. The supramolecular structure of the complex consists of an ordered multilamellar assembly where hydrated DNA helices are sandwiched between the lipid bilayers and the metal cations bind the phosphate groups of DNA to the lipid polar heads. In the range of explored incubation times, the complex coexists with the uncomplexed DPPC over the whole temperature range investigated (20-55 degrees C). Accordingly, two distinct coexisting lamellar phases are observed, one corresponding to the ternary complex and the other to the uncomplexed lipid. The structure and thermotropic phase behavior of both of these have been investigated by means of synchrotron X-ray diffraction, and the relevant structural data are deduced from experimental electron density profiles. While the uncomplexed lipid exhibits the same phase behavior as pure DPPC, that is, L beta'-P beta'-L alpha, the thermotropic behavior of the bound lipid in the complex is partially altered. This is manifested as an increase in the main transition temperature and the disappearance of the ripple phase leading to the single -phase transition. The role of the different metal cations in promoting and stabilizing the DNA condensation into the ternary complex is also discussed.

Role of regional mechanical dyssynchrony as a determinant of functional mitral regurgitation in patients with left ventricular systolic dysfunction

OBJECTIVE

To assess regional mechanical dyssynchrony as a determinant of the degree of functional mitral regurgitation (FMR).

SETTING

Tertiary cardiology clinic.

PATIENTS

74 consecutive patients with left ventricular (LV) dysfunction (ejection fraction < 40%, mean 32.2 (SD 7.3)%) were evaluated.

METHODS

Effective regurgitant orifice (ERO) area, indices of mitral deformation (systolic valvular tenting, mitral annular contraction) and of global LV function and remodelling (ejection fraction, end systolic volume, sphericity index) and local remodelling (papillary-fibrosa distance, regional wall motion score index), and tissue Doppler-derived dyssynchrony index (DI) (regional DI, defined as the standard deviation of time to peak myocardial systolic contraction of eight LV segments supporting the papillary muscles attachment) were measured.

RESULTS

All the assessed variables correlated significantly with ERO. By multivariate analysis, systolic valvular tenting was the strongest independent predictor of ERO (R(2) = 0.77, p = 0.0001), with a minor influence of papillary-fibrosa distance (R(2) = 0.77, p = 0.01) and regional DI (R(2) = 0.77, p = 0.03). Local LV remodelling (regional wall motion score index: R(2) = 0.58, p = 0.001; papillary-fibrosa distance: R(2) = 0.58, p = 0.002) and global remodelling indices (sphericity index: R(2) = 0.58, p = 0.003) were the main determinants of systolic valvular tenting, whereas regional DI did not enter into the model. Regional DI was an independent predictor of ERO (R(2) = 0.56, p = 0.005) in patients with non-ischaemic LV dysfunction but not in patients with ischaemic LV dysfunction when these groups were analysed separately.

CONCLUSIONS

The degree of FMR is associated mainly with mitral deformation indices. The regional dyssynchrony also has an independent association with ERO but with a minor influence; however, it is not a determinant of FMR in patients with ischaemic LV dysfunction.

Fe2+ promoted peroxidation of 1,2-diacyl-sn-glycero-3-phosphocholine liposomes in the presence of calf thymus DNA

The peroxidation reaction of some liposomes, namely egg yolk phosphatidylcholine (PC), dioleoyl- (DOPC) and dilinoleoyl- (DLPC) phosphocholines, promoted by ferrous ions (Fenton reaction) has been studied at the physiological pH value, in the absence and in the presence of calf thymus DNA. A catalytic effect of DNA, where the lag time reduces or is completely annihilated, together with an increase in both the yields and the rates of the reactions, has been observed. This effect of DNA has been attributed to the ability of the three components, liposomes, DNA and Fe2+, to form a stable ternary complex, which produces a reduction of the undulatory fluctuations of the hydrocarbon tails of liposomes and strengthens the packing between the acyl chains in the lipid bilayers, with the consequence of enhancing the liposome crystallinity.

Histological and microscopy FT-IR imaging study on the proliferative activity and angiogenesis in head and neck tumours

Micro Fourier transform infrared spectroscopy enables one to study small samples because of the high quality spectra that can be obtained. Biochemical and morphological changes between control and pathological tissues of head and neck tumours have been monitored drawing three-dimensional chemical maps of the main vibrational modes in the regions of interest. Comparison between spectral and histological data shows a satisfactory degree of accordance. Among all, proliferating and regressive states of the tumours can be identified.

Compressing inverse lyotropic systems: Structural behavior and energetics of dioleoyl phosphatidyl ethanolamine

The pressure effects on the stability and energetics of lipid phases in the L-alpha-dioleoyl phosphatidyl ethanolamine (DOPE)-water system are presented. Using synchrotron diffraction experiments, performed at a wide range of concentrations, pressure-induced transitions from the inverse hexagonal (H(II)) to the lamellar L(alpha) phase and from the L(alpha) to the lamellar L(beta) phase are demonstrated. Moreover, in the most dehydrated samples an intermediate phase is found between the H(II) and the L(alpha) phases, confirming that the lamellar-to-nonlamellar phase transition occurs through key intermediate structures. Simple molecular packing arguments lead to an interpretation of the phase behavior: in fact, pressure induces a progressive stiffening of the DOPE hydrocarbon chains and a reduction of the cross-sectional area. Because pressure is more effective in reducing the cross-sectional area near the terminal methyl groups than at the water-lipid interface, the curvature of that interface in the H(II) phase is reduced during compression. The work of isothermal compression was then obtained and analyzed in terms of the elastic energetic contributions that should stabilize the DOPE phases during compression. As a result, we observe that the isothermal lateral compression modulus is almost independent of concentration, but it increases as a function of pressure, suggesting that the DOPE repulsion becomes very strong while the whole lipid shape becomes more cylindrical. On the other hand, the bending rigidity is observed to decrease with increasing pressure, while the spontaneous curvature becomes less negative. This suggests that the chain repulsion becomes relatively weaker, and thus less efficient in balancing the torque of head-group repulsion, as the order parameter increases.