Maize food allergy: lipid-transfer proteins,endochitinases, and alpha-zein precursor are relevant maize allergens in double-blind placebo-controlled maize-challenge-positive patients

Italian patients with maize anaphylaxis have been shown to have IgE toward two major maize allergens: an alpha-amylase inhibitor and a 9-kDa LTP. A complete study on maize food allergens in patients with positive maize double-blind, placebo-controlled food challenge (DBPCFC) is lacking. The objective was to utilize the three maize protein fractions to identify and characterize the most relevant IgE-binding proteins recognized by the sera of Italian and Swiss patients with either a positive maize-DBPCFC or a history of maize-induced anaphylaxis. Osborne’s protein fractions of maize were extracted to obtain water-soluble, total zein, and total protein fractions. Protein IgE-binding capacity was investigated by SDS-PAGE immunoblotting using the sera from DBPCFC-positive patients and from patients with maize-induced anaphylaxis. Purified maize LTP was used to inhibit the IgE immunoblotting of the three protein fractions. IgE immunoblotting demonstrated that the 9-kDa LTP was recognized by all the Italian patients and by none of the Swiss patients. Other allergens were: 14-kDa α-amylase inhibitor, 30-kDa endochitinases A and -B, 19 kDa zein-β precursor, and 26 kDa zein-α precursor; a newly described allergen, the globulin-2 precursor, identified in the total protein fraction. It is noteworthy that maize LTP and endochitinase were cross-reactive with grape LTP and one grape endochitinase. LTP was found to be the only major allergen in Italian patients with either positive maize challenge or a history of maize-induced anaphylaxis. We have identified other maize allergens in subjects with maize food allergy, as grape cross-reactive endochitinase, however, the clinical significance of these proteins needs to be investigated in larger groups of patients with allergy to these food items.     

New synthesis of glycolipid immunostimulants RC-529 and CRX-524

An efficient and scalable synthesis of the potent vaccine adjuvant RC-529 (3) and TLR4 agonist CRX-524 (4) is described in eight steps from 1,3,4,6-tetra-O-acetyl-2-amino-2-benzyloxycarbonyl-2-deoxy-β-d-glucopyranose (10c) in ca. 25% overall yield. The synthesis features the strategic use of the N-Cbz group for β-glycosylation and the selective N,N,O-triacylation of common advanced intermediate 15 with (R)-3-tetradecanoyloxy or decanoyloxytetradecanoic acid (8, 9) late in the synthesis. A new method for preparing and enhancing the enantiopurity of (R)-3-hydroxytetradecanoic acid (6), a key component of 3 and 4 as well as bacterial lipid A, is also described.     

The analysis of serum effects on structure, size and toxicity of DDAB-DOPE and DC-Chol-DOPE lipoplexes contributes to explain their different transfection efficiency

The effect of serum on structural properties of dimethyl-dioctadecyl-ammonium bromide (DDAB)–1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposomes and DDAB–DOPE/DNA lipoplexes has been investigated by energy dispersive X-ray diffraction (EDXD) technique, at different cationic lipid/DNA weight ratios (ρ). The role of serum on the size of lipoplexes has also been studied by dynamic light scattering. Lipoplex transfection efficiency (TE) as a function of ρ, and lipoplex toxicity to C6 rat glioma cells have been evaluated in Dulbecco's Modified Eagle Medium (DMEM) with and without serum. A multi-parametric analysis concerning the role of size, structure and cytotoxicity on transfection efficiency contributes to explain the experimental observation that 3β-[N-(N′,N′-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol)–DOPE/DNA transfect C6 cells better than DDAB–DOPE/DNA lipoplexes.     

Polymerizable phospholipids: a novel class of biomaterials

Polymerizable phospholipids are organic monomers that are able to self-assemble into membranes. This is quite similar to the self assembly of naturally occurring lipid membranes found in biological systems. The polymerizable lipids can then be polymerized to stabilize these membranes. These stabilized structures have a number of different morphologies which offer a variety of technically attractive features. This article reviews the chemical and physical properties of these materials in terms of their technological applications.     

Epoxidation — a consequence of cell damage

Summary Products obtained after plant cell injury were studied by dividing white cabbage leaves (Brassica oleracea) in two parts. One part was heated to denaturate enzymes, homogenized, and stirred for six hours. After chromatographic separation and appropriate derivatization, the fractions were analyzed for low molecular weight compounds by GCMS. The other part was homogenized without cooking, but treated and analyzed in exactly the same way as the non-cooked sample. Comparison of the thus obtained products revealed that — besided already well known lipid peroxidation processes,e.g. generation of stress hormones as well as liberation and oxidation of phenolic compounds — a main but less known way of oxidative destruction was observed: epoxidation. The reaction not only involves unsaturated fatty acids, but also sterols and terpenes. This seems to be a typical response of plant cells to injury.

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Epoxidierung — Eine Folge von Zellverletzung

Zusammenfassung Zur Untersuchung der Prozesse, die nach Zellverletzung ablaufen, wurde ein Weißkohlkopf geteilt. Die eine Hälfte wurde gekocht, um Enzyme zu zerstören, und dann homogenisiert. Das Homogenisat wurde bei Raumtemperatur sechs Stunden an der Luft gerührt. Nach chromatographischer Trennung wurden die einzelnen Fraktionen nach entsprechender Derivatisierung mittels GC-MS auf niedermolekulare Inhaltsstoffe untersucht. Die andere Hälfte des Weißkrautes wurde ungekocht in gleicher Weise homogenisiert, aufgearbeitet und analysiert. Der Vergleich der so erhaltenen Produkte ergab, daß neben bereits bekannten Lipidperoxidationsprozessen wie z.B. der Bildung von Streßhormonen und der Freisetzung sowie Oxidation von Phenolen ein weniger bekannter Weg oxidativer Umwandlung beobachtet wurde: Epoxidierung. Sie betrifft nicht nur ungesättigte Fettsäuren, sondern auch Sterole und Terpene. Diese Reaktion scheint eine typische Antwort von Pflanzen auf Zellverletzung zu sein.

     

Kinetics of lipid layer formation at interfaces

A formal kinetic model of lipid layer formation at an interface in contact with a liposomal suspension is developed and investigated. Neglecting diffusion (for sufficiently high bulk concentrations) the kinetic scheme consists of two consecutive processes: (I) irreversible transformation of ‘soluble’ intact vesicles from the ‘subsurface’ layer into ‘adsorbed’ ones (‘defected’ or ‘ruptured’ liposomes, ‘mesophases’); and (II) irreversible transformation of the ‘adsorbed’ vesicles into a lipid monolayer. The resulting set of two differential equations is analyzed making use of the ‘steady-state concentration’ approach (with ‘adsorbed’ vesicles as intermediate compound). Numerical results illustrate the predicted kinetic behavior which depends on the relative magnitude of the rates of the two consecutive processes. Approximate analytical solutions in the case of a much slower process I are obtained in some limiting cases. The model is used to estimate rate constants from previously established experimental kinetic data at the air/water interface.     

Liposome-mediated conformation transition of DNA detected by molecular probe: methyl green

Recent studies have focused on the structural features of DNA-lipid assemblies. In this paper, we take methyl green (MG) as a probe molecule to detect the conformational change of DNA molecule induced by dimethyldioctadecylammonium bromide (DDAB) liposomes before the condensation process of DNA begins. DDAB-induced DNA topology changes were investigated by cyclic voltammetry (CV), circular dichroism (CD) and UV-VIS spectrometry. We find that upon binding to DNA, positively charged liposomes induce a conformational transition of DNA molecules from the native B-form to the C motif. Conformational transition in DNA results in the binding modes of MG to DNA, changing and being isolated from DNA to the solution. More stable complexes are formed between DNA and DDAB. That is also proved by the melting study of DNA.     

Fluorescence transduction of an enzyme-substrate reaction by modulation of lipid membrane structure

The emission intensity of the fluorophore nitrobenzoxadiazoledipalmitoylphosphatidylethanolamine (NBD-PE) is sensitive to local environmental structure when this species is used as a component of a phospholipid membrane. The physical and electrostatic structure of a membrane may be modulated by selective chemical reactions, and the resulting alteration in fluorescence intensity provides transduction of such selective chemical processes. One example is the reaction between the extrinsic membrane-associated enzyme acetylcholinesterase (AChE) and the substrate acetylcholine (ACh), which produces an increase in hydronium ion activity at the surface of a lipid membrane. A mechanism of transduction of the enzymatic reaction by lipid monolayer membranes was investigated by spectrofluorimetric methods and fluorescence microscopy. Mixed monolayers composed of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidic acid (DPPA) which contained 30 mol-% or more of DPPA and 1 mol-% of NBD-PE provided transduction of the AChEACh reaction. Reaction of micromolar concentrations of ACh with AChE-monolayer systems induced increases in fluorescence intensity of up to 50%. Direct observation of the microscopic structure of lipid monolayers on a time scale of minutes showed that the reaction did not drastically affect the distribution of coexisting microscopic phase domains that were present in the monolayers The fluorescence imaging and spectroscopic results did indicate that massive structural reorganization at a molecular level probably occurred in a period of seconds. The results are consistent with an electrostatic mechanism of perturbation of the structure of the monolayer in which local pH gradients associated with the reaction of AChE with substrate altered the extent of ionization of DPPA in the headgroup zone of the membrane.     

Improvement of a solid phase extraction method for analysis of lipid fractions in muscle foods

The most used method for muscle lipid fractionation into major lipid classes was modified for improving its separation efficiency. Extracted lipids from a masseter muscle of one Iberian pig were separated into neutral lipids (NL), free fatty acids (FFA) and polar lipids (PL) using aminopropyl minicolumns, following the extensively used method of Kaluzny et al. [1] (old method-OM-) and a method based on that, developed by Pinkart et al. [2] with some (modifications modified method–MM). Obtained lipid classes were further analysed by TLC and lipid fractions were identified. TLC evidenced the presence of a certain amount of PL in the NL fraction obtained with the OM. On the other hand, using the MM only an almost undetectable presence of PL was evidenced in the NL fraction. Fatty acid composition of NL, PL and FFA obtained with each method was studied by gas chromatography. Fatty acid profile of NL was strongly influenced by the separation method used. Thus, NL obtained using the OM showed higher amounts of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) and lower of monounsaturated fatty acids (MUFA) than those obtained using the MM. Moreover, NL obtained using the OM showed the presence of fatty alcohols, constituents of phospholipids (PhL) absent or present only in trace amounts in acylglycerols. This profile reflects the coelution of PL in the NL fraction. Fatty acid profile of FFA and PL fractions was also influenced by the solid phase extraction (SPE) method used, but to a lesser extent.     

Surfactants – Compounds for inactivation of SARS-CoV-2 and other enveloped viruses

We provide here a general view on the interactions of surfactants with viruses, with a particular emphasis on how such interactions can be controlled and employed for inhibiting the infectivity of enveloped viruses, including coronaviruses. The aim is to provide to interested scientists from different fields, including chemistry, physics, biochemistry, and medicine, an overview of the basic properties of surfactants and (corona)viruses, which are relevant to understanding the interactions between the two. Various types of interactions between surfactant and virus are important, and they act on different components of a virus such as the lipid envelope, membrane (envelope) proteins and nucleocapsid proteins. Accordingly, this cannot be a detailed account of all relevant aspects but instead a summary that bridges between the different disciplines. We describe concepts and cover a selection of the relevant literature as an incentive for diving deeper into the relevant material. Our focus is on more recent developments around the COVID-19 pandemic caused by SARS-CoV-2, applications of surfactants against the virus, and on the potential future use of surfactants for pandemic relief. We also cover the most important aspects of the historical development of using surfactants in combatting virus infections. We conclude that surfactants are already playing very important roles in various directions of defence against viruses, either directly, as in disinfection, or as carrier components of drug delivery systems for prophylaxis or treatment. By designing tailor-made surfactants, and consequently, advanced formulations, one can expect more and more effective use of surfactants, either directly as antiviral compounds or as part of more complex formulations.