In-Hydrogel Cell-Free Protein Expression System as Biocompatible and Implantable Biomaterial

Biomaterials capable of delivering therapeutic proteins are relevant in biomedicine, yet their manufacturing relies on centralized manufacturing chains that pose challenges to their remote implementation at the point of care. This study explores the viability of confined cell-free protein synthesis within porous hydrogels as biomaterials that dynamically produce and deliver proteins to in vitro and in vivo biological microenvironments. These functional biomaterials have the potential to be assembled as implants at the point of care. To this aim, we first entrap cell-free extracts (CFEs) from Escherichia coli containing the transcription-translation machinery, together with plasmid DNA encoding the super folded green fluorescence protein (sGFP) as a model protein, into hydrogels using various preparation methods. Agarose hydrogels result in the most suitable biomaterials to confine the protein synthesis system, demonstrating efficient sGFP production and diffusion from the core to the surface of the hydrogel. Freeze-drying (FD) of agarose hydrogels still allows for the synthesis and diffusion of sGFP, yielding a more attractive biomaterial for its reconstitution and implementation at the point of care. FD-agarose hydrogels are biocompatible in vitro, allowing for the colonization of cell microenvironments along with cell proliferation. Implantation assays of this biomaterial in a preclinical mouse model proved the feasibility of this protein synthesis approach in an in vivo context and indicated that the physical properties of the biomaterials influence their immune responses. This work introduces a promising avenue for biomaterial fabrication, enabling the in vivo synthesis and targeted delivery of proteins and opening new paths for advanced protein therapeutic approaches based on biocompatible biomaterials.

Single-Particle and Single-Molecule Characterization of Immobilized Enzymes: A Multiscale Path toward Optimizing Heterogeneous Biocatalysts

Heterogeneous biocatalysis is highly relevant in biotechnology as it offers several benefits and practical uses. To leverage the full potential of heterogeneous biocatalysts, the establishment of well-crafted protocols, and a deeper comprehension of enzyme immobilization on solid substrates are essential. These endeavors seek to optimize immobilized biocatalysts, ensuring maximal enzyme performance within confined spaces. For this aim, multidimensional characterization of heterogeneous biocatalysts is required. In this context, spectroscopic and microscopic methodologies conducted at different space and temporal scales can inform about the intraparticle enzyme kinetics, the enzyme spatial distribution, and the mass transport issues. In this Minireview, we identify enzyme immobilization, enzyme catalysis, and enzyme inactivation as the three main processes for which advanced characterization tools unveil fundamental information. Recent advances in operando characterization of immobilized enzymes at the single-particle (SP) and single-molecule (SM) levels inform about their functional properties, unlocking the full potential of heterogeneous biocatalysis toward biotechnological applications.

Region-Directed Enzyme Immobilization through Engineering Protein Surface with Histidine Clusters

Enzyme immobilization is a key enabling technology for a myriad of industrial applications, yet immobilization science is still too empirical to reach highly active and robust heterogeneous biocatalysts through a general approach. Conventional protein immobilization methods lack control over how enzymes are oriented on solid carriers, resulting in negative conformational changes that drive enzyme deactivation. Site-selective enzyme immobilization through peptide tags and protein domains addresses the orientation issue, but this approach limits the possible orientations to the N- and C-termini of the target enzyme. In this work, we engineer the surface of two model dehydrogenases to introduce histidine clusters into flexible regions not involved in catalysis, through which immobilization is driven. By varying the position and the histidine density of the clusters, we create a small library of enzyme variants to be immobilized on different carriers functionalized with different densities of various metal chelates (Co2+, Cu2+, Ni2+, and Fe3+). We first demonstrate that His-clusters can be as efficient as the conventional His-tags in immobilizing enzymes, recovering even more activity and gaining stability against some denaturing agents. Furthermore, we find that the enzyme orientation as well as the type and density of the metal chelates affect the immobilization parameters (immobilization yield and recovered activity) and the stability of the immobilized enzymes. According to proteomic studies, His-clusters enable a different enzyme orientation as compared to His-tag. Finally, these oriented heterogeneous biocatalysts are implemented in batch reactions, demonstrating that the stability achieved by an optimized orientation translates into increased operational stability.

A Multiplex Assay to Assess the Transaminase Activity toward Chemically Diverse Amine Donors

The development of methods to engineer and immobilize amine transaminases (ATAs) to improve their functionality and operational stability is gaining momentum. The quest for robust, fast, and easy-to-use methods to screen the activity of large collections of transaminases, is essential. This work presents a novel and multiplex fluorescence-based kinetic assay to assess ATA activity using 4-dimethylamino-1-naphthaldehyde as an amine acceptor. The developed assay allowed us to screen a battery of amine donors using free and immobilized ATAs from different microbial sources as biocatalysts. As a result, using chromatographic methods, 4-hydroxybenzylamine was identified as the best amine donor for the amination of 5-(hydroxymethyl)furfural. Finally, we adapted this method to determine the apparent Michaelis-Menten parameters of a model immobilized ATA at the microscopic (single-particle) level. Our studies promote the use of this multiplex, multidimensional assay to screen ATAs for further improvement.

Selective Coimmobilization of His-Tagged Enzymes on Yttrium-Stabilized Zirconia-Based Membranes for Continuous Asymmetric Bioreductions

Scalability, process control, and modularity are some of the advantages that make flow biocatalysis a key-enabling technology for green and sustainable chemistry. In this context, rigid porous solid membranes hold the promise to expand the toolbox of flow biocatalysis due to their chemical stability and inertness. Yttrium-stabilized zirconia (YSZ) fulfills these properties; however, it has been scarcely exploited as a carrier for enzymes. Here, we discovered an unprecedented interaction between YSZ materials and His-tagged enzymes that enables the fabrication of multifunctional biocatalytic membranes for bioredox cascades. X-ray photoelectron spectroscopy suggests that enzyme immobilization is driven by coordination interactions between the imidazole groups of His-tags and both Zr and Y atoms. As model enzymes, we coimmobilized in-flow a thermophilic hydroxybutyryl-CoA dehydrogenase (TtHBDH-His) and a formate dehydrogenase (His-CbFDH) for the continuous asymmetric reduction of ethyl acetoacetate with in situ redox cofactor recycling. Fluorescence confocal microscopy deciphered the spatial organization of the two coimmobilized enzymes, pointing out the importance of the coimmobilization sequence. Finally, the coimmobilized system succeeded in situ, recycling the redox cofactor, maintaining the specific productivity using only 0.05 mM NADH, and accumulating a total enzyme turnover number of 4000 in 24 h. This work presents YSZ materials as ready-to-use carriers for the site-directed enzyme in-flow immobilization and the application of the resulting heterogeneous biocatalysts for continuous biomanufacturing.

A hydrophilic interaction liquid chromatography - Tandem mass spectrometry method for the determination of phenylephrine in dried blood spots from preterm infants

A sensitive and accurate hydrophilic interaction liquid chromatography - tandem mass spectrometry method (HILIC-MS/MS) was developed and validated for the determination of phenylephrine concentration in Dried Blood Spot (DBS) samples from preterm infants, after ocular administration of an ophthalmic solution with phenylephrine. Sample preparation involved the extraction of the analyte from an 85 μL DBS sample with methanol - acetonitrile (50:50, v/v). Chromatographic separation was achieved on an ACQUITY UPLC BEH AMIDE column, under isocratic conditions within a 5 min run. Detection was achieved with a triple quadrupole MS applying electrospray ionization in positive mode. The method was fully validated and proved precise and accurate with in a linear range of 0.59-3.53 ng/ml in blood. The method was developed to provide insights on the level of exposure of infant population to phenylephrine after ocular administration.

Intraparticle Kinetics Unveil Crowding and Enzyme Distribution Effects on the Performance of Cofactor-Dependent Heterogeneous Biocatalysts

Multidimensional kinetic analysis of immobilized enzymes is essential to understand the enzyme functionality at the interface with solid materials. However, spatiotemporal kinetic characterization of heterogeneous biocatalysts on a microscopic level and under operando conditions has been rarely approached. As a case study, we selected self-sufficient heterogeneous biocatalysts where His-tagged cofactor-dependent enzymes (dehydrogenases, transaminases, and oxidases) are co-immobilized with their corresponding phosphorylated cofactors [nicotinamide adenine dinucleotide phosphate (NAD(P)H), pyridoxal phosphate (PLP), and flavin adenine dinucleotide (FAD)] on porous agarose microbeads coated with cationic polymers. These self-sufficient systems do not require the addition of exogenous cofactors to function, thus avoiding the extensive use of expensive cofactors. To comprehend the microscopic kinetics and thermodynamics of self-sufficient systems, we performed fluorescence recovery after photobleaching measurements, time-lapse fluorescence microscopy, and image analytics at both single-particle and intraparticle levels. These studies reveal a thermodynamic equilibrium that rules out the reversible interactions between the adsorbed phosphorylated cofactors and the polycations within the pores of the carriers, enabling the confined cofactors to access the active sites of the immobilized enzymes. Furthermore, this work unveils the relationship between the apparent Michaelis-Menten kinetic parameters and the enzyme density in the confined space, eliciting a negative effect of molecular crowding on the performance of some enzymes. Finally, we demonstrate that the intraparticle apparent enzyme kinetics are significantly affected by the enzyme spatial organization. Hence, multiscale characterization of immobilized enzymes serves as an instrumental tool to better understand the in operando functionality of enzymes within confined spaces.

A study of the subdiffusion of small molecules in charged polyelectrolyte multilayers

A theoretical approach has been developed here to describe the slow diffusion of small charged molecules of sodium dithionite (S₂O₄²⁻) in polyelectrolyte multilayers (PEMs) composed of polyallylamine hydrochloride (PAH) and polystyrene sulfonate (PSS), which is demonstrated here to be a case of subdifussion. Diffusion is measured experimentally by recording the quenching of the fluorescence of (7-nitrobenz-2-oxa-1,3-diazol-4yl) amino (NBD) labelled PAH layers assembled on silica particles by flow cytometry. NBD is reduced when it encounters dithionite leading to the disappearance of the fluorescence. The fluorescence decay curves show a slow diffusion of dithionite, that does not follow classical Fickean law. Dithionite diffusion in the PEMs is shown to be a non-Markovian process and the slow diffusion can be described via diffusion equations with fractional time derivatives. Results are explained assuming subdifussion of dithionite in the PEMs, as a result of the trapping of the negatively charged dithionite in the positively charged layers of PAH.

Solid-Phase Assembly of Multienzyme Systems into Artificial Cellulosomes

We herein describe a bioinspired solid-phase assembly of a multienzyme system scaffolded on an artificial cellulosome. An alcohol dehydrogenase and an ω-transaminase were fused to cohesin and dockerin domains to drive their sequential and ordered coimmobilization on agarose porous microbeads. The resulting immobilized scaffolded enzymatic cellulosome was characterized through quartz crystal microbalance with dissipation and confocal laser scanning microscopy to demonstrate that both enzymes interact with each other and physically colocalize within the microbeads. Finally, the assembled multifunctional heterogeneous biocatalyst was tested for the one-pot conversion of alcohols into amines. By using the physically colocalized enzymatic system confined into porous microbeads, the yield of the corresponding amine was 1.3 and 10 times higher than the spatially segregated immobilized system and the free enzymes, respectively. This work establishes the basis of a new concept to organize multienzyme systems at the nanoscale within solid and porous immobilization carriers.

Effects of valinomycin doping on the electrical and structural properties of planar lipid bilayers supported on polyelectrolyte multilayers

Supported Lipid Bilayers (SLBs) on Polyelectrolyte Multilayers (PEMs) have large potential as models for developing sensor devices. SLBs can be designed with receptors and channels, which benefit from the biological environment of the lipid layers, to create a sensing interface for ions and biomarkers. PEMs assembled by the Layer-by-Layer (LBL) technique and used as supports for a lipid bilayer enable an easy integration of the bilayer on almost any surface and device. For electrochemical sensors, LBL assembly enables nanoscale tunable separation of the lipid bilayer from the electrode surface, avoiding undesired effects of the electrode surface on the lipid bilayers. We study the fabrication of valinomycin-doped SLBs on PEMs as a model system for biophysical studies and for selective ion sensing. SLBs are fabricated from dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylserine (DOPS) 50:50 vesicles doped with valinomycin, as a K⁺-selective carrier. SLBs were deposited on electrodes coated with poly(allyl amine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS) multilayers. Lipid bilayer formation was monitored by using Quartz Crystal Microbalance with Dissipation (QCMD) technique and Atomic Force Microscopy (AFM). Electrochemical impedance spectroscopy (EIS) and potentiometric measurements were performed to assess K⁺ selectivity over other ions and the potential of valinomycin-doped SLBs for K⁺-sensing.

Active engineering of four-wave mixing spectral correlations in multiband hollow-core fibers

We demonstrate theoretically and experimentally a high level of control of the four-wave mixing process in an inert gas-filled inhibited-coupling guiding hollow-core photonic crystal fiber. The specific multiple-branch dispersion profile in such fibers allows both correlated and separable bi-photon states to be produced. By controlling the choice of gas and its pressure and the fiber length, we experimentally generate various joint spectral intensity profiles in a stimulated regime that is transferable to the spontaneous regime. The generated profiles may cover both spectrally separable and correlated bi-photon states and feature frequency tuning over tens of THz, demonstrating a large dynamic control that will be very useful when implemented in the spontaneous regime as a photon pair source.

Demonstration of Einstein-Podolsky-Rosen Steering Using Hybrid Continuous- and Discrete-Variable Entanglement of Light

Einstein-Podolsky-Rosen steering is known to be a key resource for one-sided device-independent quantum information protocols. Here we demonstrate steering using hybrid entanglement between continuous- and discrete-variable optical qubits. To this end, we report on suitable steering inequalities and detail the implementation and requirements for this demonstration. Steering is experimentally certified by observing a violation by more than 5 standard deviations. Our results illustrate the potential of optical hybrid entanglement for applications in heterogeneous quantum networks that would interconnect disparate physical platforms and encodings.

Gramicidin ion channels in a lipid bilayer supported on polyelectrolyte multilayer films: an electrochemical impedance study

Supported membranes on polymer cushions are of fundamental interest as models for cell membranes. The use of polyelectrolyte multilayers (PEMs) assembled by the layer by layer (LbL) technique as supports for a bilayer allows for easy integration of the lipid bilayer on surfaces and devices and for nanoscale tunable spacing of the lipid bilayer. Controlling ionic permeability in lipid bilayers supported on PEMs triggers potential applications in sensing and as models for transport phenomena in cell membranes. Lipid bilayers displaying gramicidin channels are fabricated on top of polyallylamine hydrochloride (PAH) and polystyrene sulfonate (PSS) multilayer films, by the assembly of vesicles of phosphatidylcholine and phosphatidylserine, 50 : 50 M/M, carrying gramicidin (GA). Quartz crystal microbalance with dissipation shows that the vesicles with GA fuse into a bilayer. Atomic force microscopy reveals that the presence of GA alters the bilayer topography resulting in depressions in the bilayer of around 70 nm in diameter. Electrochemical impedance spectroscopy (EIS) studies show that supported bilayers carrying GA have smaller resistances than the bilayers without GA. Lipid layers carrying GA display a higher conductance for K⁺ than for Na⁺ and are blocked in the presence of Ca²⁺.

Exploring the pH Sensitivity of Poly(allylamine) Phosphate Supramolecular Nanocarriers for Intracellular siRNA Delivery

Silencing RNA (siRNA) technologies emerge as a promising therapeutic tool for the treatment of multiple diseases. An ideal nanocarrier (NC) for siRNAs should be stable at physiological pH and release siRNAs in acidic endosomal pH, fulfilling siRNA delivery only inside cells. Here, we show a novel application of polyamine phosphate NCs (PANs) based on their capacity to load negatively charged nucleic acids and their pH stability. PANs are fabricated by complexation of phosphate anions from phosphate buffer solution (PB) with the amine groups of poly(allylamine) hydrochloride as carriers for siRNAs. PANs are stable in a narrow pH interval, from 7 to 9, and disassemble at pH's higher than 9 and lower than 6. siRNAs are encapsulated by complexation with poly(allylamine) hydrochloride before or after PAN formation. PANs with encapsulated siRNAs are stable in cell media. Once internalized in cells following endocytic pathways, PANs disassemble at the low endosomal pH and release the siRNAs into the cytoplasm. Confocal laser scanning microscopy (CLSM) images of Rhodamine Green labeled PANs (RG-PANs) with encapsulated Cy3-labeled siRNA in A549 cells show that siRNAs are released from the PANs. Colocalization experiments with labeled endosomes and either labeled siRNAs prove the translocation of siRNAs into the cytosol. As a proof of concept, it is shown that PANs with encapsulated green fluorescence protein (GFP) siRNAs silence GFP in A549 cells expressing this protein. Silencing efficacy was evaluated by flow cytometry, CLSM, and Western blot assays. These results open the way for the use of poly(allylamine) phosphate nanocarriers for the intracellular delivery of genetic materials.

Raman-tailored photonic crystal fiber for telecom band photon-pair generation

We report on the experimental characterization of a novel nonlinear liquid-filled hollow-core photonic crystal fiber for the generation of photon pairs at a telecommunication wavelength through spontaneous four-wave mixing (SFWM). We show that the optimization procedure in view of this application links the choice of the nonlinear liquid to the design parameters of the fiber, and we give an example of such an optimization at telecom wavelengths. Combining the modeling of the fiber and classical characterization techniques at these wavelengths, we identify for the chosen fiber and liquid combination SFWM phase-matching frequency ranges with no Raman scattering noise contamination. This is a first step toward obtaining a telecom band fibered photon-pair source with a high signal-to-noise ratio.

Continuous-Variable Instantaneous Quantum Computing is Hard to Sample

Instantaneous quantum computing is a subuniversal quantum complexity class, whose circuits have proven to be hard to simulate classically in the discrete-variable realm. We extend this proof to the continuous-variable (CV) domain by using squeezed states and homodyne detection, and by exploring the properties of postselected circuits. In order to treat postselection in CVs, we consider finitely resolved homodyne detectors, corresponding to a realistic scheme based on discrete probability distributions of the measurement outcomes. The unavoidable errors stemming from the use of finitely squeezed states are suppressed through a qubit-into-oscillator Gottesman-Kitaev-Preskill encoding of quantum information, which was previously shown to enable fault-tolerant CV quantum computation. Finally, we show that, in order to render postselected computational classes in CVs meaningful, a logarithmic scaling of the squeezing parameter with the circuit size is necessary, translating into a polynomial scaling of the input energy.

Experimental verification of multipartite entanglement in quantum networks

Multipartite entangled states are a fundamental resource for a wide range of quantum information processing tasks. In particular, in quantum networks, it is essential for the parties involved to be able to verify if entanglement is present before they carry out a given distributed task. Here we design and experimentally demonstrate a protocol that allows any party in a network to check if a source is distributing a genuinely multipartite entangled state, even in the presence of untrusted parties. The protocol remains secure against dishonest behaviour of the source and other parties, including the use of system imperfections to their advantage. We demonstrate the verification protocol in a three- and four-party setting using polarization-entangled photons, highlighting its potential for realistic photonic quantum communication and networking applications.

Multipartite entangled states are a fundamental resource for quantum information processing tasks; it is thus important to verify their presence. Here the authors present and demonstrate a protocol that allows any party in a network to verify if an untrusted source is distributing multipartite entangled states.

High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study

Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 10(7) Ω cm(2), which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance.

Lipid Layers on Polyelectrolyte Multilayers: Understanding Lipid-Polyelectrolyte Interactions and Applications on the Surface Engineering of Nanomaterials

In this manuscript we review work of our group on the assembly of lipid layers on top of polyelectrolyte multilayers (PEMs). The assembly of lipid layers with zwitterionic and charged lipids on PEMs is studied as a function of lipid and polyelectrolyte composition by the Quartz Crystal Microbalance. Polyelectrolyte lipid interactions are studied by means of Atomic Force Spectroscopy. We also show the coating of lipid layers for engineering different nanomaterials, i.e., carbon nanotubes and poly(lactic-co-glycolic) nanoparticles and how these can be used to decrease in vitro toxicity and to direct the intracellular localization of nanomaterials.

Virosome engineering of colloidal particles and surfaces: bioinspired fusion to supported lipid layers

Immunostimulating reconstituted influenza virosomes (IRIVs) are liposomes with functional viral envelope glycoproteins: influenza virus hemagglutinin (HA) and neuraminidase intercalated in the phospholipid bilayer. Here we address the fusion of IRIVs to artificial supported lipid membranes assembled on polyelectrolyte multilayers on both colloidal particles and planar substrates. The R18 assay is used to prove the IRIV fusion in dependence of pH, temperature and HA concentration. IRIVs display a pH-dependent fusion mechanism, fusing at low pH in analogy to the influenza virus. The pH dependence is confirmed by the Quartz Crystal Microbalance technique. Atomic Force Microscopy imaging shows that at low pH virosomes are integrated in the supported membrane displaying flattened features and a reduced vertical thickness. Virosome fusion offers a new strategy for transferring biological functions on artificial supported membranes with potential applications in targeted delivery and sensing.

The effect of top-layer chemistry on the formation of supported lipid bilayers on polyelectrolyte multilayers: primary versus quaternary amines

The influence of the surface chemistry of PEMs on the formation of lipid bilayers is studied here for PEMs with different cationic amines as a top layer, and polystyrene sulfonate (PSS) as a polyanion.

Fabrication of hybrid graphene oxide/polyelectrolyte capsules by means of layer-by-layer assembly on erythrocyte cell templates

A novel and facile method was developed to produce hybrid graphene oxide (GO)-polyelectrolyte (PE) capsules using erythrocyte cells as templates. The capsules are easily produced through the layer-by-layer technique using alternating polyelectrolyte layers and GO sheets. The amount of GO and therefore its coverage in the resulting capsules can be tuned by adjusting the concentration of the GO dispersion during the assembly. The capsules retain the approximate shape and size of the erythrocyte template after the latter is totally removed by oxidation with NaOCl in water. The PE/GO capsules maintain their integrity and can be placed or located on other surfaces such as in a device. When the capsules are dried in air, they collapse to form a film that is approximately twice the thickness of the capsule membrane. AFM images in the present study suggest a film thickness of approx. 30 nm for the capsules in the collapsed state implying a thickness of approx. 15 nm for the layers in the collapsed capsule membrane. The polyelectrolytes used in the present study were polyallylamine hydrochloride (PAH) and polystyrenesulfonate sodium salt (PSS). Capsules where characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and Raman microscopy, the constituent layers by zeta potential and GO by TEM, XRD, and Raman and FTIR spectroscopies.

Role of Hydrogen Bonding and Polyanion Composition in the Formation of Lipid Bilayers on Top of Polyelectrolyte Multilayers

The self-assembly of mixed vesicles of zwitterionic phosphatidylcholine (PC) and anionic phosphatidylserine (PS) phospholipids on top of polyelectrolyte multilayers (PEMs) of poly(allylamine hydrochloride) (PAH), as a polycation, and polystyrenesulfonate (PSS), as a polyanion, is investigated as a function of the vesicle composition by means of the quartz crystal microbalance with dissipation (QCM-D), cryo-transmission electron microscopy (Cryo-TEM), atomic force microscopy (AFM), and atomic force spectroscopy (AFS). Vesicles with molar percentages of PS between 50% and 70% result in the formation of lipid bilayers on top of the PEMs. Vesicles with over 50% of PC or over 80% of PS do not assembly into bilayers. AFS studies performed with a PAH-modified cantilever approaching and retracting from the lipid assemblies reveal that the main interaction between PAH and the lipids takes place through hydrogen bonding between the amine groups of PAH and the carboxylate and phosphate groups of PS and with the phosphate groups of PC. The interaction of PAH with PS is much stronger than with PC. AFS measurements on assemblies with 50% PC and 50% PS revealed similar adhesion forces to pure PS assemblies, but the PAH chains can reorganize much better on the lipids as a consequence of the presence of PC. QCM-D experiments show that vesicles with a lipid composition of 50% PC and 50% PS do not form bilayers if PSS is replaced by alginate (Alg) or poly(acrylic acid) (PAA).

Therapeutic hypothermia in asphyxiated neonates with hypoxic-ischemic encephalopathy: A single-center experience from its first application in Greece

BACKGROUND/AIM

Therapeutic hypothermia has become an established therapy in asphyxiated neonates with evidence of moderate/severe hypoxic-ischemic encephalopathy. Herein, we describe our recent experience with total body cooling in asphyxiated neonates, which is the first relevant report in Greece.

PATIENTS AND METHODS

The medical records of all asphyxiated newborns treated with therapeutic hypothermia in our center between September 2010 and October 2013 were retrospectively reviewed. We recorded data related to neonatal-perinatal characteristics, whole body cooling and outcome.

RESULTS

Twelve asphyxiated neonates [median gestational age 38 weeks (36-40)] received whole body cooling (rectal temperature 33.5 ± 0.5 (o)C for 72 hours) during the study period for moderate (n=3) and severe (n=9) hypoxic-ischemic encephalopathy. Cooling was passive in 4 and active in 8 (66.7%) cases. Therapeutic hypothermia was initiated at the median age of 5 hours (0.5-11) after birth. Seven neonates survived (58.3%) to hospital discharge. On follow-up (7-35 months), neurodevelopment outcome was normal in 1 case, while 3, 1 and 2 subjects had mild, moderate and severe impairment, respectively.

CONCLUSIONS

Our initial experience with whole body cooling supports its beneficial effect in asphyxiated neonates. This treatment should be offered in all centers involved in the care of such neonates using either simple means (passive cooling) or automated cooling devices. Hippokratia 2014; 18 (3): 226-230.

Neonatal outcomes of late preterm deliveries with pre-eclampsia

AIM

The aim of the study was to examine the impact of pre-eclampsia on neonatal outcomes of late preterm deliveries.

METHODS

A retrospective study was conducted, enrolling pregnancies delivered between 34 0/7 and 36 6/7 weeks of gestation during the period 2004-2007 in a large tertiary center. Pregnancies were divided in group 1, including those complicated with pre-eclampsia and group 2, including normotensive cases. Epidemiological characteristics, mode of delivery and complications contributing in late preterm delivery were initially studied. Neonatal morbidity parameters of our interest included mean Apgar score in the 1st and 5th minute, admission to Neonatal Intensive Care Unit (NICU) and need for emergency intubation. Intrauterine growth retardation (IUGR), low birth weight (LBW) and very LBW (VLBW), respiratory distress syndrome (RDS), hypoglycemia, NICU infection, abnormal cerebral ultrasonographic findings and duration of NICU residence were also compared between the two groups.

RESULTS

Out of 363 late preterm pregnancies, 29 (8%) were delivered because of pre-eclampsia. Mean gestational week and birth weight were significantly lower in group 1. The rate of elective caesarean section was also significantly higher in this group. The same observation was made concerning rates of IUGR, LBW and VLBW neonates. Furthermore, incidence of NICU admission and hypoglycemia were significantly higher in the group of infants born by pre-eclamptic mothers. Incidence of RDS and cerebral echo pathology were also higher, but without significant difference when compared to group 2.

CONCLUSION

Neonatal adverse outcomes were increased in late preterm infants of pre-eclamptic women in comparison with those of normotensive women.

Effect of gestational diabetes and intrauterine growth restriction on the offspring's circulating galanin at birth

CONTEXT

Experimental studies linked gestational diabetes mellitus (GDM) and intrauterine growth restriction (IUGR) with altered expression of the offspring's hypothalamic galanin mRNA, possibly contributing to the development of obesity and metabolic syndrome in later life. We hypothesized that plasma galanin levels at birth would reflect presumably altered hypothalamic galanin expression and production that cannot be assessed in the human offspring.

OBJECTIVE

Our objective was to investigate whether neonates born to GDM mothers or being IUGR differ from healthy ones in circulating galanin at birth.

DESIGN, PATIENTS, AND METHODS

Twenty-five neonates born to GDM mothers, 25 with IUGR, and 15 healthy neonates (controls) were prospectively studied. Neonatal plasma galanin levels were assayed immediately after birth by using enzyme immunoassay.

RESULTS

Neonatal plasma galanin showed a high variability within each group and did not differ significantly among the three groups of neonates. No correlation between plasma galanin and anthropometric maternal and neonatal data was found. Multiple linear regression confirmed that the neonatal group (infants of diabetic mothers, IUGR, and controls) was not an independent predictor for galanin levels at birth after controlling for possible confounders, i.e. maternal body mass index and weight gain during pregnancy and neonatal body mass index.

CONCLUSIONS

Circulating galanin levels at birth are not affected by GDM and IUGR, providing no evidence for alternations in hypothalamic galanin expression and secretion in humans, as they were previously documented in experimental models. This fact precludes the use of plasma galanin as an early indicator for the development of obesity and metabolic syndrome in this high-risk population.

Comparable effect of conventional ventilation versus early high-frequency oscillation on serum CC16 and IL-6 levels in preterm neonates

OBJECTIVE

Clara cell 16 kD protein (CC16) and interleukin (IL)-6 have been used as peripheral blood biomarkers of alveolar leakage and inflammation, respectively. Thus, their measurement in the bloodstream could be used to assess ventilator-induced lung injury. The objective of this study was to evaluate the effect of optimized synchronized intermittent mandatory ventilation (SIMV) and high-frequency oscillatory ventilation (HFOV) on circulating CC16 and IL-6 levels when used as the initial ventilation modes in preterm neonates.

STUDY DESIGN

Single center, prospective, randomized clinical study in preterm neonates (gestational age 30 weeks) requiring mechanical ventilation within the first 2 h of life. Serum CC16 and IL-6 were measured on establishment of the assigned ventilation mode after admission, at days 3 and 14 of life as well as at 36 weeks postmenstrual age. Demographic-perinatal data and clinical parameters were also recorded.

RESULT

Of the 30 neonates studied, 24 (gestational age 27.1±1.7 weeks, birth weight 942±214 g) were finally analyzed, equally assigned into the SIMV and HFOV groups. Both groups had comparable demographic-perinatal characteristics and clinical parameters. Serum CC16 and IL-6 altered significantly over time (repeated-measures analysis of variance, both P<0.001). However, changes were not affected by the ventilation mode. Post hoc analysis showed a significant decrease in CC16 and IL-6 from birth up to 36 weeks postmenstrual age in both groups.

CONCLUSION

In preterm neonates, SIMV and HFOV are associated with comparable circulating CC16 and IL-6 levels. These findings suggest a similar alveolar leakage and systemic inflammation with any of the ventilation modes evaluated when their usage is optimized.

Operative vaginal delivery in singleton term pregnancies: short-term maternal and neonatal outcomes

BACKGROUND

The rate of operative vaginal delivery has remained stable the last decade, however the rate of vacuum has increased against forceps application. Different maternal and neonatal outcomes have been proposed by many reports. The aim of the present study is to compare the short term maternal and neonatal outcomes between vacuum and forceps delivery.

MATERIAL AND METHODS

We conducted a medical record review of live born singleton, vacuum and forceps-deliveries. Maternal and delivery characteristics were recorded. Maternal and neonatal outcomes were also assessed. Out of 7098 deliveries, 374 were instrument assisted, 324 were conducted by vacuum (86.7%) and 50 by forceps (13.3%).

RESULTS

The incidence of 3rd degree lacerations and periurethral hematomas was similar between vacuum and forceps (3.4% vs. 2% and 0.3% vs 0% respectively), while perineal hematomas were more common in forceps compared with vacuum application (2% vs 0.3% respectively), albeit not significantly. The rate of neonates with Apgar scores

CONCLUSION

Results of the present study indicate that both modes of instrumental vaginal delivery are safe with respect to maternal morbidity and neonatal trauma. However, forceps application increases the risk of neonatal compromise consequently necessitating their admission in the NICU.

Collapse

Key Words

• forceps
• instrumental delivery
• perinatal outcomes
• vacuum

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

N Prapas 4th Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki, Greece
I Kalogiannidis
S Masoura
E Diamanti
A Makedos
D Drossou
G Makedos

Collapse

Quantum teleportation with a quantum dot single photon source

We report the experimental demonstration of a quantum teleportation protocol with a semiconductor single photon source. Two qubits, a target and an ancilla, each defined by a single photon occupying two optical modes (dual-rail qubit), were generated independently by the single photon source. Upon measurement of two modes from different qubits and postselection, the state of the two remaining modes was found to reproduce the state of the target qubit. In particular, the coherence between the target qubit modes was transferred to the output modes to a large extent. The observed fidelity is 80%, in agreement with the residual distinguishability between consecutive photons from the source. An improved version of this teleportation scheme using more ancillas is the building block of the recent Knill, Laflamme, and Milburn proposal for efficient linear optics quantum computation.

Bone resorption is increased in young adults with thalassaemia major

Bone disease in patients with thalassaemia major is a multifactorial and still poorly understood process. The present study evaluated 45 thalassaemic patients using dual X-ray absorptiometry at three sites (lumbar spine, head of femur and forearm) to assess bone mineral density, in parallel with a series of biochemical markers to measure bone formation and bone resorption. To identify possible interfering factors, our patients were grouped according to whether or not they needed transfusion therapy; the presence of hypogonadism was also considered. Our results showed that patients on regular transfusions had a markedly low bone mineral density in contrast to those not requiring blood support and that this finding was more pronounced in the hypogonadic group, irrespectively of sex. The decrease of bone mineral density values was more prominent in the forearm, thus making this site particularly interesting for such studies. Bone formation, as evidenced by the levels of serum alkaline phosphatase and osteocalcin, did not appear to be impaired, while bone resorption was grossly increased in all patient groups. The latter process was clearly evident using the recently introduced measurement of the urinary N-terminal peptides of collagen type I, the sensitivity of which has already been established in other groups of osteoporotic patients. Our conclusion is that, in spite of the severe bone destruction that occurs in thalassaemia major, the fact that bone formation remains intact calls for a more intensive treatment comprising hormonal replacement, bisphosphonates and other agents.

Antigenic and molecular characterization of wild type 1 poliovirus causing outbreaks of poliomyelitis in Albania and neighboring countries in 1996

Mass vaccination has led poliomyelitis to become a rare disease in a large part of the world, including Western Europe. However, in the past 20 years wild polioviruses imported from countries where polio is endemic have been responsible for outbreaks in otherwise polio-free European countries. We report on the characterization of poliovirus isolates from a large outbreak of poliomyelitis that occurred in Albania in 1996 and that also spread to the neighboring countries of Yugoslavia and Greece. The epidemics involved 145 subjects, mostly young adults, and caused persisting paralysis in 87 individuals and 16 deaths. The agent responsible for the outbreak was isolated from 74 patients and was identified as wild type 1 poliovirus by both immunological and molecular methods. Sequence analysis of the genome demonstrated the involvement of a single virus strain throughout the epidemics, and genotyping analysis showed 95% homology of the strain with a wild type 1 poliovirus strain isolated in Pakistan in 1995. Neutralization assays with both human sera and monoclonal antibodies were performed to analyze the antigenic structure of the epidemic strain, suggesting its peculiar antigenic characteristics. The presented data underline the current risks of outbreaks due to imported wild poliovirus and emphasize the need to improve vaccination efforts and also the need to implement surveillance in countries free of indigenous wild poliovirus.

Surveillance of suspected poliomyelitis in Albania, 1980-1995: suggestion of increased risk of vaccine associated poliomyelitis

Surveillance of suspected poliomyelitis cases was conducted in Albania from 1980 through 1995. A total of 93 cases were reported, 11 of which were clinically defined as poliomyelitis cases according to WHO criteria. Poliovirus was isolated from six subjects who were defined as contact vaccine-associated cases. Characterization of isolates by both antigenic and molecular methods showed that, in all cases, the disease was associated with type 2 or 3 polioviruses of vaccine origin with retromutations known to be associated with loss of Sabin attenuated phenotype. Infection occurred despite the fact that all patients had records of previous immunization with oral polio vaccine (OPV), suggesting a failure of vaccination. Four of the five patients from which poliovirus could not be isolated were classified as possible recipient vaccine-associated poliomyelitis on the basis of serology data (presence of antibodies against all three polioviruses) and the temporal association between the latest dose of vaccine received and onset of paralysis. Virological investigation on healthy contacts of the poliomyelitic patients yielded the isolation of a further 12 Sabin-like polio revertant viruses, mostly type 2 and 3. A detailed study of the non-polio acute flaccid paralysis (AFP) cases and their healthy contacts revealed the presence of several enteroviruses, namely Echo, coxsackie and, in three cases type 2 or 3 Sabin-like polioviruses. Overall, these data suggest the absence of circulation of wild-type poliovirus in Albania from 1980 to 1995, before the recent outbreak of poliomyelitis in 1996, and emphasize the need for active surveillance of AFP and laboratory characterization of virus isolates to monitor vaccination efficacy.

Selective IgA deficiency in a patient with Hashimoto's thyroiditis. Case report

We describe a case of Hashimoto's thyroiditis in which, eight years after initial diagnosis, an isolated (selective) IgA deficiency was detected. It is not clear which of these two conditions followed the other (both aetiologically and chronologically); indications and arguments for and against both hypotheses are discussed.

An epidemiological study on viral infantile diarrhoea in Tirana

During the period May 1993-April 1994, an epidemiological survey was conducted on enteric viruses which cause gastroenteritis in infants and young children in Tirana, Albania. Specimens from 321 cases were screened by direct electron microscopy and by an enzyme-linked immunosorbent assay specific for rotavirus group A antigen. By ultrastructural analysis, rotaviruses were detected in 10.3% of cases and adenoviruses in 0.6%, whereas small round structured viruses and small round viruses were found in 2.8% and 2.2% of cases, respectively. Different percentages of rotavirus excretors were revealed by enzyme-linked immunosorbent assay (12.15%) and electron microscopy. Samples rotavirus-positive in at least one of these assays were also analyzed by agglutination of latex particles and electron microscopy results were confirmed. Analysis of electron microscopy-positive samples by rotaviral RNA polyacrylamide gel electrophoresis showed five different long electropherotypes of rotavirus among which a single, largely predominant electropherotype (65.5%) was observed.

Electropherotypes of rotavirus strains causing gastroenteritis in infants and young children in Tirana, Albania, from 1988 to 1991

During 1988-1991, an epidemiological survey was conducted in Tirana (Albania) on group A rotavirus strains which cause gastroenteritis in infants and young children. Rotaviruses were detected in 312 of 1,241 (25.1%) examined specimens from children with acute diarrhoea. Viruses were detected throughout the study period. Among the 72 rotavirus strains tested for double-stranded RNA (dsRNA) electrophoretic migration pattern, 9 different electropherotypes were recognized, 1 of those being more frequent than the others. At the beginning and at the end of the examined period (1988 and 1990-1991) two different long electropherotypes were predominant, whereas in 1989 (middle period) short electropherotypes were common indicating an involvement of virus strains with short electropherotypes in hospitalization-requiring diarrhoeas occurring in the area surveyed in that year.

Follow-up of very low birth weight infants after erythropoietin treatment to prevent anemia of prematurity

OBJECTIVE

Treatment with recombinant human erythropoietin (rHuEPO) stimulates erythropoiesis and reduces the need for transfusions in hospitalized preterm infants. The aim of our study was to follow very low birth weight infants after the initial 6 weeks of rHuEPO treatment.

DESIGN AND METHODS

We randomly assigned 97 very low birth weight infants with a gestational age of 31 weeks or less and birth weight of 1500 gm or less to receive rHuEPO, 300 units/kg per week (erythropoietin (EPO) 300, n = 33), rHuEPO, 750 units/kg per week (EPO 750; n = 28), or no treatment (control, n = 36). The rHuEPO was administered from the first week of life for 6 weeks. After EPO therapy was discontinued, 75 neonates were followed weekly until discharge and at 3, 6, and 12 months of age.

RESULTS

Mean numbers (+/- SD) of packed erythrocyte transfusions per patient from the time rHuEPO therapy was discontinued until discharge were 0.38 +/- 0.64 (EPO 300), 0.23 +/- 0.52 (EPO 750), 0.9 +/- 1.1 (control) (p < 0.05 in both EPO groups vs control). Mean reticulocyte counts at the sixth week were 6% +/- 2.2% (EPO 300), 6.9% +/- 2.2% (EPO 750), and 3.1% +/- 2.6% (control) in the three groups (p < 0.01 in both EPO groups vs control), and at the eighth week were 4.7% +/- 2.8% (EPO 300), 5.4% +/- 2.7% (EPO 750), and 2.6% +/- 2.2% (control) (p < 0.01 in both EPO groups vs control). Serum ferritin levels were significantly higher at the sixth week, and the percentage of hemoglobin F was significantly lower at 6, 8, and 10 weeks in the control group versus EPO groups. At 3, 6, and 12 months of age, there were no differences in reticulocytes, ferritin, HbF, and growth among groups.

CONCLUSION

Preterm infants who received rHuEPO had a normal pattern of erythropoiesis after the drug was discontinued. These data provide strong evidence that the anemia of prematurity is the result of a transient developmental abnormality in EPO production.

Concentrations of main serum opsonins in early infancy

The evolution of the main serum opsonins in neonates and infants of varying gestational age was investigated to provide reference values for these opsonins in early infancy. Serum concentrations of immunoglobulins, IgG subclasses, C3, C4 and fibronectin were serially measured from birth until the age of 6 months in term and preterm infants. Measurements were performed by rate nephelometry. Five hundred and sixty six neonates (gestational age 26-41 weeks) were examined at birth, 233 at 1 month, 218 at 3 months, and 147 at 6 months, respectively. The same measurements were performed in 54 pairs of neonatal/maternal samples and in 230 apparently healthy adults. Gestational age had a significant impact on serum IgG, IgG subclasses, C3 and C4 up till the third month, and on fibronectin until the first month. No such impact was observed for IgA and IgM. Sixteen per cent of the neonates had IgM concentrations higher than 0.2 g/l at birth, suggesting that the critical concentration of serum IgM at birth for suspected intrauterine infection should be reconsidered. Concentrations of all opsonins at birth were significantly lower than adult reference values. They only approached or even reached adult values by the third or the sixth month. Data from analysis of the neonatal and the corresponding maternal sera indicate that there is a preferential active transplacental transport of IgG subclasses in the order of IgG1, IgG3, IgG2 and IgG4. These results show that concentrations of immunoglobulins, C3, C4 and fibronectin undergo changes during the first months of life, depending not only on the infants' postnatal age but also on gestational age.

Serum concentrations of 10 acute-phase proteins in healthy term and preterm infants from birth to age 6 months

Aiming to define the evolution pattern of 10 acute-phase proteins in early infancy, we measured nephelometrically the serum concentrations of albumin, prealbumin, retinol-binding protein, transferrin, ceruloplasmin, hemopexin, haptoglobin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, and alpha 1-antitrypsin in 395 term and preterm infants (gestational ages 26-41 weeks). Measurements were performed within 24 h after birth and then at the end of 1 (n = 171), 3 (n = 155), and 6 (n = 90) months afterwards. Data obtained from 250 healthy adults were used as adult reference values. All proteins increased progressively with postnatal age, except for alpha 1-antitrypsin, which remained stable from birth to the 6th month. Concentrations of almost all measured proteins were significantly lower in preterm than in term infants in the first 3 months. Compared with adult values, alpha 2-macroglobulin and alpha 1-antitrypsin were higher in infants throughout the 6 months. The other proteins were significantly lower at birth than adult values but after 6 months, only albumin, prealbumin, retinol-binding protein, and alpha 1-acid glycoprotein still remained lower in infants. Thus both gestational and postnatal age should be considered when interpreting concentrations of these proteins in early infancy.

Serum concentrations of 10 acute-phase proteins in healthy term and preterm infants from birth to age 6 months

Aiming to define the evolution pattern of 10 acute-phase proteins in early infancy, we measured nephelometrically the serum concentrations of albumin, prealbumin, retinol-binding protein, transferrin, ceruloplasmin, hemopexin, haptoglobin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, and alpha 1-antitrypsin in 395 term and preterm infants (gestational ages 26-41 weeks). Measurements were performed within 24 h after birth and then at the end of 1 (n = 171), 3 (n = 155), and 6 (n = 90) months afterwards. Data obtained from 250 healthy adults were used as adult reference values. All proteins increased progressively with postnatal age, except for alpha 1-antitrypsin, which remained stable from birth to the 6th month. Concentrations of almost all measured proteins were significantly lower in preterm than in term infants in the first 3 months. Compared with adult values, alpha 2-macroglobulin and alpha 1-antitrypsin were higher in infants throughout the 6 months. The other proteins were significantly lower at birth than adult values but after 6 months, only albumin, prealbumin, retinol-binding protein, and alpha 1-acid glycoprotein still remained lower in infants. Thus both gestational and postnatal age should be considered when interpreting concentrations of these proteins in early infancy.