Relationship among Low T3 Levels, Type 3 Deiodinase, Oxidative Stress, and Mortality in Sepsis and Septic Shock: Defining Patient Outcomes.

Low T3 syndrome occurs frequently in patients with sepsis. Type 3 deiodinase (DIO3) is present in immune cells, but there is no description of its presence in patients with sepsis. Here, we aimed to determine the prognostic impact of thyroid hormones levels (TH), measured on ICU admission, on mortality and evolution to chronic critical illness (CCI) and the presence of DIO3 in white cells. We used a prospective cohort study with a follow-up for 28 days or deceased. Low T3 levels at admission were present in 86.5% of the patients. DIO3 was induced by 55% of blood immune cells. The cutoff value of 60 pg/mL for T3 displayed a sensitivity of 81% and specificity of 64% for predicting death, with an odds ratio of 4.89. Lower T3 yielded an area under the receiver operating characteristic curve of 0.76 for mortality and 0.75 for evolution to CCI, thus displaying better performance than commonly used prognostic scores. The high expression of DIO3 in white cells provides a novel mechanism to explain the reduction in T3 levels in sepsis patients. Further, low T3 levels independently predict progression to CCI and mortality within 28 days for sepsis and septic shock patients.

Micro-Scale Shear Kneading-Gluten Network Development under Multiple Stress-Relaxation Steps and Evaluation via Multiwave Rheology.

To evaluate the kneading process of wheat flour dough, the state of the art is a subsequent and static measuring step on kneaded dough samples. In this study, an in-line measurement setup was set up in a rheometer based on previously validated shear kneading processes. With this approach, the challenge of sample transfer between the kneader and a measurement device was overcome. With the developed approach, an analysis of the dynamic development of the dough is possible. Through consecutive stress-relaxation steps with increasing deformation, a kneading setup in a conventional rheometer is implemented. Fitting of the shear stress curve with a linearization approach, as well as fitting of the relaxation modulus after each kneading step, is a new way to evaluate the matrix development. Subsequently, multiwave rheology is used to validate the kneading process in-line. The shear kneading setup was capable of producing an optimally developed dough matrix close to the reference kneading time of 150 ± 7.9 s (n = 3). The linearization approach as well as the power-law fit of the relaxation modulus revealed gluten network development comparable to the reference dough. With this approach, a deeper insight into gluten network development and crosslinking processes during wheat flour dough kneading is given.

Size-Dependent Variability in Flow and Viscoelastic Behavior of Levan Produced by Gluconobacter albidus TMW 2.1191.

Levan is a fructan-type exopolysaccharide which is produced by many microbes from sucrose via extracellular levansucrases. The hydrocolloid properties of levan depend on its molecular weight, while it is unknown why and to what extent levan is functionally diverse depending on its size. The aim of our study was to gain deeper insight into the size-dependent functional variability of levan. For this purpose, levans of different sizes were produced using the water kefir isolate Gluconobacter albidus TMW 2.1191 and subsequently rheologically characterized. Three levan types could be identified, which are similarly branched, but differ significantly in their molecular size and rheological properties. The smallest levan (<107 Da), produced without adjustment of the pH, exhibited Newton-like flow behavior up to a specific concentration of 25% (w/v). By contrast, larger levans (>108 Da) produced at pH ≥ 4.5 were shear-thinning, and the levan produced at pH 5.0 showed a gel-like behavior at 5% (w/v). A third (intermediate) levan variant was obtained through production in buffers at pH 4.0 and exhibited the properties of a viscoelastic fluid up to concentrations of 15% (w/v). Our study reveals that the rheological properties of levan are determined by its size and polydispersity, rather than by the amount of levan used or the structural composition.

VUV-photolysis of aqueous solutions of hydroxylamine and nitric oxide. Effect of organic matter: phenol.

VUV-irradiation of aqueous solutions containing hydroxylamine (NH2OH) in its acid form (NH3OH+) and phenol (C6H5OH) results in the simultaneous mineralization of the organic substrate and the almost quantitative reduction of NH3OH+ to ammonium ions (NH4+). Irradiation of aqueous solutions of NH3OH+ in the absence of organic substrates showed the formation of nitrate (NO3-) and nitrite (NO2-) and minor quantities of NH4+. In line with these experiments, VUV-irradiation of aqueous solutions of nitrogen monoxide (NO˙) yields NH4+ only when C6H5OH is simultaneously mineralized. A possible reaction mechanism is discussed, where reactions of NO˙ and NH3OH+ with hydrogen atoms (H˙), hydroxyl radicals (HO˙) and hydrated electrons (e-aq), all generated by the VUV-photochemically initiated homolysis of water, are of great importance to the observed results. In the presence of phenol, competition between phenol and either NO˙ or NH3OH+ for these reactive intermediates in the primary volume of reactions strongly determines the oxidation state and nature of the N-containing products. C-Centered radicals and intermediate products of reactions may also have an important effect on the overall mechanism. The present results are discussed in relation to the actual state of knowledge presented in the literature.

Rheological characterization of the exopolysaccharide Paenan in surfactant systems.

Rheology-controlling agents are of importance for numerous products in a variety of industries. Replacement of synthetic chemicals with natural additives is desired in light of current environmental awareness and limited fossil resources. This study investigates the rheological features of Paenan, an exopolysaccharide produced by Paenibacillus polymyxa. Paenan exhibits highly shear-thinning flow behavior at concentrations ≥0.1% in 0.5% NaCl. Because of its pronounced intermolecular network, it forms stable, weak gels, thereby delivering elasticity as well as thixotropy. Application-relevant flow behavior is obtained with 60-65% less polymer as compared to the benchmark commercial products Xanthan and Gellan. In mixtures with surfactants (sodium lauryl ether sulfate, cetrimonium chloride, cocamidopropyl betaine, or lauryl glucoside), Paenan displays outstanding compatibility with every class of surfactant, making it superior to the partially incompatible Xanthan and Gellan. The weak-gel character of Paenan/surfactant systems is retained with three out of four surfactants, rendering Paenan highly interesting for various applications.

Deformation and rupture of Dunaliella salina at high shear rates without the use of thickeners.

BACKGROUND: High-density cultures require operating below the critical threshold of shear stress, in order to avoid reducing the specific growth rate of the cells. When determining this threshold, direct inspection of the cells in flow provides insight into the conditions of shearing. OBJECTIVE: Aim of this study was using a novel rheo-optical setup for the observation of cells in laminar shear flow and the determination of the critical shear stress required to damage them in their natural environment. METHODS: Dunaliella salina cells were sheared and observed in flow for shear stresses of up to 90 Pa, at ambient temperature, without adding thickeners. The critical shear stress was determined by fitting a hydrodynamics-based criterion to the experimental data on the percentage of deformed cells after shearing. RESULTS: Single cells, clusters and strings of cells were visible in shear flow. The strings formed at maximum shear stresses of 10 Pa or higher. Cells lost motility for maximum shear stresses higher than 15 Pa, and more than 80% of the cells were deformed at maximum shear stresses higher than 60 Pa. The estimated critical shear stress was 18 Pa. CONCLUSIONS: Shear stresses higher than 18 Pa should be avoided when cultivating D. salina.

Continuous process of the vacuum ultraviolet- (VUV-) photochemical oxidation of thiophene in the gas phase.

Thiophene was taken as a model compound for investigations on the efficiency of a continuous process of the vacuum-ultraviolet- (VUV-) photochemically initiated oxidation and mineralization of sulfur containing organic compounds in the gas phase. In the presence of molecular oxygen, atomic oxygen and ozone were photochemically generated and are assumed to initiate or participate in the (thermal) oxidation network. Addition of water vapor for an additional initiation of the oxidation by hydroxyl radicals did not accelerate the process. For comparison, thiophene was exposed to ozone and oxidized under otherwise the same experimental conditions, but complete mineralization was only found in the photochemical process and for relatively small concentrations of the substrate. The result may be explained by low rates of secondary thermal reactions of a number of identified intermediate products. Combining already published results and mechanistic hypotheses with the results of the present work, pathways of oxidative degradation are proposed. The photolysis of thiophene in molecular nitrogen confirmed earlier findings.

The use of chemical actinometry for the evaluation of the light absorption efficiency in scattering photopolymerizable miniemulsions.

Oil-in-water miniemulsions containing a mixture of monomers as the dispersed organic phase have been shown recently to be promising media for the development of photoinitiated polymerization processes. Albeit a crucial factor for a successful application, the efficiency of light absorption by the photoinitiator in these highly scattering systems is difficult to evaluate. In this work, a well-characterized water insoluble chemical actinometer (DFIS) replaced the oil-soluble photoinitiator, and was used as a probe and a model for UV light absorption in miniemulsions of variable droplet sizes and organic phase compositions (i.e. at different levels of scattered light). In the first step, the photon flux absorbed by the actinometer was determined in model miniemulsions based on an inert solvent (ethyl acetate), at a low oil phase content (3.0-6.0 wt%). For these low to moderately scattering systems, the photon flux absorbed by the actinometer in the miniemulsions was comparable to that in a homogeneous solution of ethyl acetate. In the second step, the absorbed photon flux was investigated in photopolymerizable miniemulsions (a mixture of acrylate monomers as oil phase). Surprisingly, in spite of much higher scattering coefficients than those found for ethyl acetate based miniemulsions of otherwise the same composition, the photon flux absorbed by the actinometer in photopolymerizable miniemulsions showed only a small decreasing trend. Such a result may be considered favorable for the further development of applications of photopolymerizations in miniemulsions.

Preparative mass-spectrometry profiling of bioactive metabolites in Saudi-Arabian propolis fractionated by high-speed countercurrent chromatography and off-line atmospheric pressure chemical ionization mass-spectrometry injection.

Propolis is a glue material collected by honeybees which is used to seal cracks in beehives and to protect the bee population from infections. Propolis resins have a long history in medicinal use as a natural remedy. The multiple biological properties are related to variations in their chemical compositions. Geographical settings and availability of plant sources are important factors for the occurrence of specific natural products in propolis. A propolis ethylacetate extract (800mg) from Saudi Arabia (Al-Baha region) was separated by preparative scale high-speed countercurrent chromatography (HSCCC) using a non-aqueous solvent system n-hexane-ACN (1:1, v/v). For multiple metabolite detection, the resulting HSCCC-fractions were sequentially injected off-line into an atmospheric pressure chemical ionization mass-spectrometry (APCI-MS/MS) device, and a reconstituted mass spectrometry profile of the preparative run was visualized by selected ion traces. Best ion-intensities for detected compounds were obtained in the negative APCI mode and monitored occurring co-elution effects. HSCCC and successive purification steps resulted in the isolation and characterization of various bioactive natural products such as (12E)- and (12Z)-communic acid, sandaracopimaric acid, (+)-ferruginol, (+)-totarol, and 3ß-acetoxy-19(29)-taraxasten-20a-ol using EI-, APCI-MS and 1D/2D-NMR. Cycloartenol-derivatives and triterpene acetates were isolated in mixtures and elucidated by EI-MS and 1D-NMR. Free fatty acids, and two labdane fatty acid esters were identified by APCI-MS/MS. In total 19 metabolites have been identified. The novel combination of HSCCC fractionation, and APCI-MS-target-guided molecular mass profiling improve efficiency of lead-structure identification.

Micellar control of the photooxidation pathways of 10-methyl phenothiazine: electron versus energy transfer mechanisms.

10-Methyl phenothiazine (MPS) was chosen as a model compound to investigate the effects of compartmentalisation and of charged interfaces on the primary mechanisms involved in the phototoxic reactions related to phenothiazine drugs. Two most important pathways resulting from the interaction of the triplet excited state of MPS ((3)MPS*) with molecular oxygen ((3)O2) have to be considered: (i) energy transfer producing singlet oxygen ((1)O2) and (ii) electron transfer generating the superoxide anion (O2˙(-)) and the radical cation (MPS˙(+)). The quantum yields of (1)O2 production by MPS solubilized in the dispersed pseudo-phase of aqueous micellar systems were found to be similar to those determined in solvents of various polarities, regardless of the anionic or cationic nature of the surfactant (SDS or CTAC). However, micellar compartmentalisation and surfactant charge affect considerably both the sensitized and the self-sensitized photooxidation of MPS. The formation of 10-methyl phenothiazine sulfoxide (MPSO), produced by the reaction of MPS with (1)O2, proceeds at a higher rate in SDS micelles than in neat polar solvents. This result may be explained by the protonation of the zwitterionic intermediate Z (MPS(+)OO(-)) at the micellar interface to yield the corresponding cation C (MPS(+)OOH) that is stabilized in the negatively charged micelles and reacts much faster with MPS than Z to yield MPSO. The electron transfer reaction from (3)MPS* to O2 yielding MPS˙(+) and O2˙(-) is also enhanced in SDS micelles, as back electron transfer (BET) is prevented by ejection of O2˙(-) to the aqueous bulk phase and stabilization of MPS˙(+) in the anionic micelles. The size of the SDS micelles modulates the relative contribution of each pathway (formation of MPSO or MPS˙(+)) to the overall conversion of MPS to its oxidation products. Photooxidation of MPS in cationic micelles is a very slow process, as the formation of neither C nor MPS˙(+) is favoured in positively charged micelles.

Self sensitized photooxidation of N-methyl phenothiazine: acidity control of the competition between electron and energy transfer mechanisms.

The reaction pathways following electronic excitation of 10-methyl phenothiazine (MPS) in the presence of oxygen have been investigated as a contribution to establish the mechanisms involved in the phototoxic reactions related to phenothiazine drugs. In the context of previously published results, the pathways of oxidation via the radical cation and/or by reactive oxygen species, such as singlet oxygen and superoxide anion, are of particular interest. The effects of polarity of the medium as well as of proton donors on the different reaction pathways, in particular on the formation of reactive oxygen species and the intermediates of the oxidation of 10-methyl phenothiazine, have been investigated. No reaction was observed in non-polar solvents. In polar solvents, both self-sensitized and sensitized singlet oxygen generation lead to the oxidation of MPS and the production of 10-methyl phenothiazine sulfoxide (MPSO) most probably via a zwitterionic persulfoxide. During self-sensitized photooxidation of MPS in the presence of proton donors, such as carboxylic acids, the zwitterionic intermediate is protonated to the corresponding cation that in turn facilitates the reaction with a second molecule of MPS. In the presence of strong acids however, the formation of the radical cation of MPS and of the superoxide anion, by electron transfer from the triplet excited state of MPS to molecular oxygen, competes efficiently with singlet oxygen formation. In this case, the scavenging of the superoxide anion by protons to yield its conjugated acid (hydroperoxyl radical) and the subsequent disproportionation of the latter prevents back electron transfer.

Formation of hydrogen peroxide by VUV-photolysis of water and aqueous solutions with methanol.

The hydrogen peroxide production upon vacuum ultraviolet (VUV) irradiation of water is reviewed, because published results from the last 10 years lead to conflicting mechanistic interpretations. This work confirms that in pure water, hydrogen peroxide is only produced in the presence of molecular oxygen. Mechanistic schemes explain these findings and confirm earlier statements that recombination of hydroxyl radicals is kinetically disfavoured. In agreement with other recent publications, this work confirms that enhanced hydrogen peroxide production takes place upon VUV irradiation of aqueous solutions of organic compounds. For these investigations, methanol was chosen as an organic model compound. During photolyses, hydrogen peroxide, dissolved molecular oxygen, pH-value of the reaction system, methanol and its products of oxidative degradation were analyzed, and kinetic studies were undertaken to explain the evolution of the concentrations of these components.

Oxidation of polystyrene aerosols by VUV-photolysis and/or ozone.

Aerosols of submicron polystyrene particles were oxidized by either vacuum-ultraviolet (VUV) irradiation in the presence of molecular oxygen (O(2)) and/or by ozone (O(3)). Different degrees of oxidation and oxidative degradation were reached by VUV-photolysis depending on radiant energy, O(2) and H(2)O concentrations in the bulk gas mixture as well as on particle diameter. The same functionalization was obtained by exposing the aerosol to O(3), however, oxidation, in particular oxidative degradation, was less efficient. The evolution of hydroxyl and carbonyl functions introduced was quantified by ATR-FTIR spectroscopy of filtered particles, and oxidative degradation of the polymer particles was confirmed by determining size and number of aerosol particles before and after oxidation. Efficiency analyses are based on the results of an O(3) actinometry and on an evaluation of the rate of absorbed photons by the aerosol particles in function of their size.

Quenching of the fluorescence of aromatic pterins by deoxynucleotides.

Steady-state and time-resolved studies of the fluorescence of four aromatic unconjugated pterins (pterin (Ptr), 6-(hydroxymethyl)pterin (Hmp), 6-methylpterin (Mep), and 6,7-dimethylpterin (Dmp)) in aqueous solutions in the presence of different nucleotides (2'-deoxyguanosine 5'-monophosphate (dGMP), 2'-deoxyadenosine 5'-monophosphate (dAMP), and 2'-deoxycytosine 5'-monophosphate (dCMP)) have been performed using the single-photon counting technique. The singlet excited states of acid forms of pterins are deactivated by purine nucleotides (dGMP and dAMP) via a combination of dynamic and static processes. The efficiency of the dynamic quenching is high, independently of the nature of the purine base of the nucleotide and of the chemical structure of the substituents linked to the pterin moiety. Analysis of the static quenching indicates that ground-state association between pterins and purine nucleotides takes place, but the formation of the corresponding complexes is significant only at relatively high reactant concentrations. The quenching of the fluorescence of acid forms of pterin derivatives by dCMP, a pyrimidine nucleotide, is slightly less efficient than the quenching by purine nucleotides and is purely dynamic. In alkaline media, the fluorescence quenching is much less efficient than in acidic media, the deactivation by purine nucleotides being purely dynamic, whereas quenching by dCMP is negligible. Possible mechanisms for the quenching of fluorescence of pterin derivatives by the different nucleotides are discussed.

Histone deacetylase inhibitors sensitize tumour cells for cytotoxic effects of natural killer cells.

Histone deacetylase inhibitors (HDIs) are emerging as potent anti-tumour agents which induce cell cycle arrest, differentiation and/or apoptosis in many tumour cells. Furthermore, they render tumour cells more sensitive to other therapeutic regimens like ionizing radiation, chemotherapy and recombinant tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we show that the HDIs suberoylanilide hydroxamic acid (SAHA; vorinostat), sodium butyrate (NaB) and MS-275 sensitized DAOY and PC3 tumour cells for the cytotoxic effects of IL-2-activated PBMCs. In (51)Cr-release assays, blockade of the activating NK receptors DNAM-1, NKG2D and the NCRs completely abrogated tumour cell lysis, revealing that NK cells were the main effector cells involved. HDIs increased the tumour surface expression of ligands for the activating NK receptors NKG2D and DNAM-1 thereby facilitating tumour cell recognition by NK cells. These results suggest that the combination of HDIs and immunotherapy may be an effective strategy for anti-cancer therapy.

Photosensitization of 2'-deoxyadenosine-5'-monophosphate by pterin.

UV-A radiation (320-400 nm) induces damages to the DNA molecule and its components through photosensitized reactions. Pterins, heterocyclic compounds widespread in biological systems, participate in relevant biological processes and are able to act as photosensitizers. We have investigated the photosensitization of 2'-deoxyadenosine-5'-monophosphate (dAMP) by pterin (PT) in aqueous solution under UV-A radiation. The effect of pH was evaluated, the participation of oxygen was investigated and the products analyzed. Kinetic studies revealed that the reactivity of dAMP towards singlet oxygen (1O2) is very low and that this reactive oxygen species does not participate in the mechanism of photosensitization, although it is produced by PT upon UV-A excitation. In contrast, analysis of irradiated solutions by means of electrospray ionization mass spectrometry strongly suggested that 8-oxo-7,8-dihydro-2'-deoxyadenosine-5'-monophosphate (8-oxo-dAMP) was produced, indicating that the photosensitized oxidation takes place via a type I mechanism (electron transfer).

Mineralization of CCl4 by the UVC-photolysis of hydrogen peroxide in the presence of methanol.

A method for a photochemically induced mineralization of CCl4 is described in which use is made of reductive radicals. The UVC-photolysis (254 nm) of H2O2 added to aqueous solutions of CCl4 is leading to the homolysis of the oxidant yielding hydroxyl radicals (HO) that subsequently react with added methanol to generate hydroxymethyl radicals (CH2OH). The latter radicals initiate mineralization of CCl4 by reductive C-Cl bond splitting. CHCl3, C2Cl4 and C2Cl6 were found as reaction intermediates, but are quantitatively depleted in a parallel oxidative reaction manifold leading to mineralization. Carbon dioxide radical anion, CO2(-), an intermediate in the mineralization pathway of methanol, is also shown to initiate the mineralization of CCl4 by reductive dechlorination. A reaction mechanism is proposed and validated with computer simulations of all the experimental results.

Characterization of nanostructured surfaces generated by reconstitution of the porin MspA from Mycobacterium smegmatis.

Nanostructures with long-term stability at the surface of gold electrodes are generated by reconstituting the porin MspA from Mycobacterium smegmatis into a specially designed monolayer of long-chain lipid surfactant on gold. Tailored surface coverage of gold electrodes with long-chain surfactants is achieved by electrochemically assisted deposition of organic thiosulfates (Bunte salts). The subsequent reconstitution of the octameric-pore MspA is guided by its extraordinary self-assembling properties. Importantly, electrochemical reduction of copper(II) yields copper nanoparticles within the MspA nanopores. Electrochemical impedance spectroscopy, reflection electron microscopy, and atomic force microscopy (AFM) show that: 1) the MspA pores within the self-assembled monolayer (SAM) are monodisperse and electrochemically active, 2) MspA reconstitutes in SAMs and with a 10-nm thickness, 3) AFM is a suitable method to detect pores within SAMs, and 4) the electrochemical reduction of Cu2+ to Cu0 under overpotential conditions starts within the MspA pores.

Singlet oxygen (O2(1Deltag)) quenching by dihydropterins.

Pterins belong to a class of heterocyclic compounds present in a wide range of living systems. They participate in relevant biological functions and are involved in different photobiological processes. Dihydropterins are one of the biologically active forms of pterins. The photoinduced production and quenching of singlet oxygen (1O2) by a series of dihydropterins (7,8-dihydrobiopterin (DHBPT), 7,8-dihydroneopterin (DHNPT), 6-formyl-7,8-dihydropterin (FDHPT), sepiapterin (SPT), 7,8-dihydrofolic acid (DHFA), and 7,8-dihydroxanthopterin (DHXPT)) in aqueous solution at physiological pH ( approximately 7) were investigated, and the quantum yields of 1O2 production (PhiDelta) and rate constants of total quenching (kt) of 1O2 were determined. Studied compounds do not produce 1O2 under UV-A irradiation and are very efficient 1O2 quenchers. The chemical reactions between 1O2 and dihydropterin derivatives were investigated, and the corresponding rate constants (kr) were found to be particularly high. The oxidized pterin derivatives, biopterin (BPT), neopterin (NPT), 6-formylpterin (FPT), and folic acid (FA), were identified and quantified during the reaction of 1O2 with DHBPT, DHNPT, FDHPT, and DHFA, respectively. Besides the oxidation of the dihydropyrazine ring to yield the corresponding oxidized pterins, a second oxidation pathway, leading to fragmentation of the dihydropterin and formation of non-pterinic products, was identified. Mechanisms and biological implications are discussed.

Myoglobin modified electrodes as anchors for d metal cationic complexes.

The capability of adsorption of different electroactive cationic Re(V)-amine complexes onto myoglobin-containing electrodes has been investigated. The goal of this work was the development of an Au/thiol/myo electrode and, after incubation of such ensemble in the presence of three different Re(V)-amine complexes, the evaluation of the extent of surface coverage by the complexes (as a way to evaluate the interaction complex-protein) using electrochemical techniques. Our results showed that a protein-containing electrode could therefore be used for the detection of the interaction of small electroactive cationic complexes and the biomolecule. The extent of the coverage of the myoglobin electrode by the complex depends on the number of free tails from the ligands and the total charge of the complex.