Revealing the nuclearity of iron citrate complexes at biologically relevant conditions

Citric acid plays an ubiquitous role in the complexation of essential metals like iron and thus it has a key function making them biologically available. For this, iron(III) citrate complexes are considered among the most significant coordinated forms of ferric iron that take place in biochemical processes of all living organisms. Although these systems hold great biological relevance, their coordination chemistry has not been fully elucidated yet. The current study aimed to investigate the speciation of iron(III) citrate using Mössbauer and electron paramagnetic resonance spectroscopies. Our aim was to gain insights into the structure and nuclearity of the complexes depending on the pH and iron to citrate ratio. By applying the frozen solution technique, the results obtained directly reflect the iron speciation present in the aqueous solution. At 1:1 iron:citrate molar ratio, polynuclear species prevailed forming most probably a trinuclear structure. In the case of citrate excess, the coexistence of several monoiron species with different coordination environments was confirmed. The stability of the polynuclear complexes was checked in the presence of organic solvents.

Zinc Ferrite Nanoparticle Coatings on Austenitic Alloy Steel

The phase transition of austenitic stainless steel of commercial label CL20ES and zinc ferrite nanoparticles was studied in an oxidative atmosphere of dry air to develop a low-cost, effective technique for covering-layer fabrication. CL20ES powder and zinc ferrite powder were mechanically mixed. This mixture was studied in an atmosphere of dry air at different annealing temperatures from room temperature to 900 °C. The employed characterization techniques are X-ray powder diffraction, Mössbauer spectroscopy in the transmission geometry, and scanning electron microscopy with elemental mapping. The fabricated layers were also characterized by surface-specific techniques such as conversion electron Mössbauer spectroscopy and grazing incidence X-ray powder diffraction. The analyzed powder mixture shows resistance against oxidation in dry air and high temperatures. These results were employed to produce zinc ferrite covering layers on 3D-printed cylinders of CL20ES. The results show a predisposition of zinc ferrite to be recrystallized at temperatures above 350 °C without the production of corrosive substances on steel. The zinc ferrite layers were analyzed by an ultrasonic hardness tester as well, which proved the hardness enhancement.

Microwave-Enhanced Crystalline Properties of Zinc Ferrite Nanoparticles

Two series of ZnFe₂O₄ mixed cubic spinel nanoparticles were prepared by a coprecipitation method, where a solution of Fe³⁺ and Zn²⁺ was alkalised by a solution of NaOH. While the first series was prepared by a careful mixing of the two solutions, the microwave radiation was used to enhance the reaction in the other series of samples. The effect of the microwave heating on the properties of the prepared particles is investigated. X-ray powder diffraction (XRD), ⁵⁷Fe Mössbauer spectroscopy and magnetometry were employed to prove the cubic structure and superparamagnetic behavior of the samples. The particle size in the range of nanometers was investigated by a transmission electron microscopy (TEM), and the N₂ adsorption measurements were used to determine the BET area of the samples. The stoichiometry and the chemical purity were proven by energy dispersive spectroscopy (EDS). Additionally, the inversion factor was determined using the low temperature Mössbauer spectra in the external magnetic field. The microwave heating had a significant effect on the mean coherent length. On the other hand, it had a lesser influence on the size and BET surface area of the prepared nanoparticles.

Microwave Synthesis of Magnetite Nanoparticles and Mg-Doped Magnetite Nanoparticles by Precipitation of Fe2+ Ions

This study is focused on a simple and fast synthesis of nonstoichiometric magnetite nanoparticles with the chemical formula Fe_3-XO₄ and magnesium ferrite nanoparticles (Mg_1-XFe_2+XO₄). The nanoparticles were prepared with Fe²⁺ ions (FeSO₄ · H₂O) alkalised by KOH under oxidative conditions and in a microwave field. X-ray powder diffraction (XRD) and ⁵⁷Fe transmission Mössbauer spectroscopy were used to determine the phase composition and crystal structure in detail. The presence of synthetic magnetite, maghemite, goethite, and magnesium ferrite was observed. Room temperature Mössbauer spectroscopy revealed the existence of ferromagnetic sublattices and superparamagnetic fraction. The superparamagnetic component corresponds to magnesium ferrite nanoparticles. Low temperature Mössbauer spectroscopy was used to locate the blocking temperature of superparamagnetic nanoparticles and to separate the sublattices. The presumed spherical morphology of nanoparticles and their size under 100 nm have been confirmed by transmission electron microscopy (TEM). The obtained results were used to provide possible reaction scheme, which serves to tailor the synthesis to a desired application.

Environmentally friendly synthesized and magnetically recoverable designed ferrite photo-catalysts for wastewater treatment applications

Fenton processes are promising wastewater treatment alternatives for bio-recalcitrant compounds. Three different methods (i.e., reverse microemulsion, sol-gel, and combustion) were designed to synthesize environmentally friendly ferrites as magnetically recoverable catalysts to be applied for the decomposition of two pharmaceuticals (ciprofloxacin and carbamazepine) that are frequently detected in water bodies. The catalysts were used in a heterogeneous solar photo-Fenton treatment to save the cost of applying high-energy UV radiation sources, and was performed under a slightly basic pH to avoid metal leaching and adding salts for pH adjustment. All the developed catalysts resulted in the effective treatment of ciprofloxacin and carbamazepine in both synthetic and real domestic wastewater. In particular, the sol-gel synthesized ferrite was more magnetic and more suitable for reuse. The degradation pathways of both compounds were elucidated for this treatment. The degradation of ciprofloxacin involved attacks to the quinolone and piperazine rings. The degradation pathway of carbamazepine involved the formation of hydroxyl carbamazepine and dihydroxy carbamazepine before yielding acridine by hydrogen abstraction, decarboxylation, and amine cleavage, which would be further oxidized.

Silver nanoparticles by atomic vapour deposition on an alcohol micro-jet

We achieved sputter deposition of silver atoms onto liquid alcohols by injection of solvents into vacuum via a liquid microjet. Mixing silver atoms into ethanol by this method produced metallic silver nanoparticles. These had a broad, log-normal size distribution, with median size between 3.3 ± 1.4 nm and 2.0 ± 0.7 nm, depending on experiment geometry; and a broad plasmon absorption band centred around 450 nm. We also deposited silver atoms into a solution of colloidal silica nanoparticles, generating silver-decorated silica particles with consistent decoration of almost one silver particle to each silica sphere. The silver-silica mixture showed increased colloidal stability and yield of silver, along with a narrowed size distribution and a narrower plasmon band blue-shifted to 410 nm. Significant methanol loss of 1.65 × 10-7 mol MeOH per g per s from the mature silver-silica solutions suggests we have reproduced known silica supported silver catalysts. The excellent distribution of silver on each silica sphere shows this technique has potential to improve the distribution of catalytically active particles in supported catalysts.

Chloroplasts preferentially take up ferric-citrate over iron-nicotianamine complexes in Brassica napus

Fe uptake machinery of chloroplasts prefers to utilise Fe(III)-citrate over Fe-nicotianamine complexes. Iron uptake in chloroplasts is a process of prime importance. Although a few members of their iron transport machinery were identified, the substrate preference of the system is still unknown. Intact chloroplasts of oilseed rape (Brassica napus) were purified and subjected to iron uptake studies using natural and artificial iron complexes. Fe-nicotianamine (NA) complexes were characterised by 5 K, 5 T Mössbauer spectrometry. Expression of components of the chloroplast Fe uptake machinery was also studied. Fe(III)-NA contained a minor paramagnetic Fe(II) component (ca. 9%), a paramagnetic Fe(III) component exhibiting dimeric or oligomeric structure (ca. 20%), and a Fe(III) complex, likely being a monomeric structure, which undergoes slow electronic relaxation at 5 K (ca. 61%). Fe(II)-NA contained more than one similar chemical Fe(II) environment with no sign of Fe(III) components. Chloroplasts preferred Fe(III)-citrate compared to Fe(III)-NA and Fe(II)-NA, but also to Fe(III)-EDTA and Fe(III)-o,o'EDDHA, and the K_m value was lower for Fe(III)-citrate than for the Fe-NA complexes. Only the uptake of Fe(III)-citrate was light-dependent. Regarding the components of the chloroplast Fe uptake system, only genes of the reduction-based Fe uptake system showed high expression. Chloroplasts more effectively utilize Fe(III)-citrate, but hardly Fe-NA complexes in Fe uptake.

Prevalence and the role of CCR5Δ32 heterozygosity in disease progression in HIV positive patients in the Czech Republic

BACKGROUND

Entry of human immunodeficiency virus type 1 (HIV-1) in target cells is enabled by CD4 receptor and one of two co-receptors, CXCR4 or CCR5. Deletion of 32 bp in CCR5 gene (CCR5Δ32) in both alleles provides strong but not absolute resistance to HIV-1 infection and deletion in one allele slows disease progression to AIDS. Here, we analyzed the prevalence and the role of CCR5Δ32 heterozygosity on the disease progression in HIV positive patients in the Czech Republic.

PATIENTS AND METHODS

A total of 92 HIV-1 seropositive subjects that included 80 Czech individuals from the AIDS center in the Hospital Na Bulovce in Prague were enrolled in CCR5 genotyping as a part of a study of the role of HIV fitness on disease progression. DNA was extracted from patient’s peripheral blood mononuclear cells and subjected to real-time PCR with specific probes detecting wild-type and 32 bp-deleted CCR5 variants. A subgroup of 74 antiretroviral therapy-naive patients with more than one year of follow-up was used to determine the role of the CCR5Δ32 heterozygous phenotype in disease progression.

RESULTS

CCR5Δ32 was found heterozygous in 23.8% of 80 Czech HIV-1 seropositive individuals which is very similar to 21% and 24% prevalence reported in HIV negative Czech population. Homozygous mutant variant was not detected. In CCR5Δ32 heterozygous group we observed slightly higher mean CD4+ T-cell count and lower mean plasma viremia levels.

CONCLUSIONS

Overall, our study indicates no obvious benefit of CCR5Δ32 heterozygosity on HIV transmission and only small benefit on disease progression in the Czech HIV-1 cohort.

Transformations of ferrates(iv,v,vi) in liquids: Mössbauer spectroscopy of frozen solutions

Two-step charge disproportionation mechanism of 3Fe(iv) to 2Fe(iii) and Fe(vi) via Fe(v) in ethanol.

Incidence of cancer and overall risk of mortality in individuals treated with raltegravir-based and non-raltegravir-based combination antiretroviral therapy regimens

Objectives

There are currently few data on the long‐term risk of cancer and death in individuals taking raltegravir (RAL). The aim of this analysis was to evaluate whether there is evidence for an association.

Methods

The EuroSIDA cohort was divided into three groups: those starting RAL‐based combination antiretroviral therapy (cART) on or after 21 December 2007 (RAL); a historical cohort (HIST) of individuals adding a new antiretroviral (ARV) drug (not RAL) to their cART between 1 January 2005 and 20 December 2007, and a concurrent cohort (CONC) of individuals adding a new ARV drug (not RAL) to their cART on or after 21 December 2007. Baseline characteristics were compared using logistic regression. The incidences of newly diagnosed malignancies and death were compared using Poisson regression.

Results

The RAL cohort included 1470 individuals [with 4058 person‐years of follow‐up (PYFU)] compared with 3787 (4472 PYFU) and 4467 (10 691 PYFU) in the HIST and CONC cohorts, respectively. The prevalence of non‐AIDS‐related malignancies prior to baseline tended to be higher in the RAL cohort vs. the HIST cohort [adjusted odds ratio (aOR) 1.31; 95% confidence interval (CI) 0.95–1.80] and vs. the CONC cohort (aOR 1.89; 95% CI 1.37–2.61). In intention‐to‐treat (ITT) analysis (events: RAL, 50; HIST, 45; CONC, 127), the incidence of all new malignancies was 1.11 (95% CI 0.84–1.46) per 100 PYFU in the RAL cohort vs. 1.20 (95% CI 0.90–1.61) and 0.83 (95% CI 0.70–0.99) in the HIST and CONC cohorts, respectively. After adjustment, there was no evidence for a difference in the risk of malignancies [adjusted rate ratio (RR) 0.73; 95% CI 0.47–1.14 for RALvs. HIST; RR 0.95; 95% CI 0.65–1.39 for RALvs. CONC] or mortality (adjusted RR 0.87; 95% CI 0.53–1.43 for RALvs. HIST; RR 1.14; 95% CI 0.76–1.72 for RALvs. CONC).

Conclusions

We found no evidence for an oncogenic risk or poorer survival associated with using RAL compared with control groups.

Degradation of the cyanotoxin microcystin-LR using iron-based photocatalysts under visible light illumination

In this study, a simple and low-cost method to synthesize iron(III) oxide nanopowders in large quantity was successfully developed for the photocatalytic degradation of microcystin-LR (MC-LR). Two visible light-active iron(III) oxide samples (MG-9 calcined at 200 °C for 5 h and MG-11 calcined at 180 °C for 16 h) with a particle size of 5-20 nm were prepared via thermal decomposition of ferrous oxalate dihydrate in air without any other modifications such as doping. The synthesized samples were characterized by X-ray powder diffraction, ⁵⁷Fe Mössbauer spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) specific surface area analysis, and UV-visible diffuse reflectance spectroscopy. The samples exhibited similar phase composition (a mixture of α-Fe₂O₃ and γ-Fe₂O₃), particle size distribution (5-20 nm), particle morphology, and degree of agglomeration, but different specific surface areas (234 m² g^-1 for MG-9 and 207 m² g^-1 for MG-11). The results confirmed higher photocatalytic activity of the catalyst with higher specific surface area. The highest photocatalytic activity of the sample to decompose MC-LR was observed at solution pH of 3.0 and catalyst loading of 0.5 g L^-1 due to large amount of MC-LR adsorption, but a little iron dissolution of 0.0065 wt% was observed. However, no iron leaching was observed at pH 5.8 even though the overall MC-LR removal was slightly lower than at pH 3.0. Thus, the pH 5.8 could be an appropriate operating condition for the catalyst to avoid problems of iron contamination by the catalyst. Moreover, magnetic behavior of γ-Fe₂O₃ gives a possibility for an easy separation of the catalyst particles after their use.

Iron supported on bioinspired green silica for water remediation

Iron has been used previously in water decontamination, either unsupported or supported on clays, polymers, carbons or ceramics such as silica. However, the reported synthesis procedures are tedious, lengthy (involving various steps), and either utilise or produce toxic chemicals. Herein, the use of a simple, rapid, bio-inspired green synthesis method is reported to prepare, for the first time, a family of iron supported on green nanosilica materials (Fe@GN) to create new technological solutions for water remediation. In particular, Fe@GN were employed for the removal of arsenate ions as a model for potentially toxic elements in aqueous solution. Several characterization techniques were used to study the physical, structural and chemical properties of the new Fe@GN. When evaluated as an adsorption platform for the removal of arsenate ions, Fe@GN exhibited high adsorption capacity (69 mg of As per g of Fe@GN) with superior kinetics (reaching ∼35 mg As per g sorbent per hr) - threefold higher than the highest removal rates reported to date. Moreover, a method was developed to regenerate the Fe@GN allowing for a full recovery and reuse of the adsorbent in subsequent extractions; strongly highlighting the potential technological benefits of these new green materials.

Remarkable efficiency of phosphate removal: Ferrate(VI)-induced in situ sorption on core-shell nanoparticles

Despite the importance of phosphorus as a nutrient for humans and its role in ecological sustainability, its high abundance, resulting in large part from human activities, causes eutrophication that negatively affects the environment and public health. Here, we present the use of ferrate(VI) as an alternative agent for removing phosphorus from aqueous media. We address the mechanism of phosphate removal as a function of the Fe/P mass ratio and the pH value of the solution. The isoelectric point of γ-Fe2O3 nanoparticles, formed as dominant Fe(VI) decomposition products, was identified to play a crucial role in predicting their efficiency in removing of phosphates. Importantly, it was found that the removal efficiency dramatically changes if Fe(VI) is added before (ex-situ conditions) or after (in-situ conditions) the introduction of phosphates into water. Removal under in-situ conditions showed remarkable sorption capacity of 143.4 mg P per gram of ferric precipitates due to better accessibility of active surface sites on in-situ formed ferric oxides/oxyhydroxides. At pH = 6.0-7.0, complete removal of phosphates was observed at a relatively low Fe/P mass ratio (5:1). The results show that phosphates are removed from water solely by sorption on the surface of γ-Fe2O3/γ-FeOOH core/shell nanoparticles. The advantages of Fe(VI) utilization include its environmentally friendly nature, the possibility of easy separation of the final product from water by a magnetic field or by natural settling, and the capacity for successful phosphate elimination at pH values near the neutral range and at low Fe/P mass ratios.

Impact of inorganic buffering ions on the stability of Fe(vi) in aqueous solution: role of the carbonate ion

An iron compound of +6 oxidation state (Fe(VI)O4(2-), Fe(vi)) is a green molecule for various applications (water oxidation catalyst, organic transformation for synthesis, and water remediation agent). However, its use is hindered because of its inherent decay in aqueous solution. This study presents a systematic kinetics investigation of the decay of ferrate(vi) in the presence of inorganic buffering ions (borate, phosphate, and carbonate) at a pH range from 6.0 to 9.0. When the heterogeneous decay of Fe(vi) on ferric products was inhibited by phosphate, detailed kinetic analysis revealed that the carbonate anion enhanced the Fe(vi) decay rate, compared to phosphate and borate ions. The order of the Fe(vi) decay rate under neutral solution conditions was carbonate > phosphate ≥ borate. In alkaline solution, the decay rates of Fe(vi) were similar for the studied buffering ions. The decay of Fe(vi) in the presence of the carbonate ion was described by mixed first- and second-order kinetics and the first-order rate constant (k1') had a linear relationship with the concentration of the carbonate ion at a neutral pH (k1' = 0.023 + 3.54 × [carbonate] L mol(-1) s(-1)). The analysis of the Fe(vi) decay intermediates/products (˙O2(-), H2O2, and O2) suggests similar decay pathways in the presence of different buffering anions. The impact of carbonate ions on the size of the nanoparticles of the Fe(iii) precipitate, the final reduced form of Fe(vi), was studied using transmission electron microscopy, (57)Fe Mössbauer spectroscopy, and magnetization measurements. The results indicated that carbonate ions induce the formation of ultrasmall iron(iii) oxyhydroxide nanoparticles (<5 nm), which apparently contribute to increased decay of Fe(vi) due to their larger specific surface area. The described homogeneous reaction of carbonate with Fe(vi) has important implications in the efficiency of environmental Fe(vi) applications. On the other hand, the observed low reactivity of borate with Fe(vi) demonstrates that borate is the least reactive buffer in studies of Fe(vi) reactivity in neutral solutions.

Revisiting the iron pools in cucumber roots: identification and localization

Fe deficiency responses in Strategy I causes a shift from the formation of partially removable hydrous ferric oxide on the root surface to the accumulation of Fe-citrate in the xylem. Iron may accumulate in various chemical forms during its uptake and assimilation in roots. The permanent and transient Fe microenvironments formed during these processes in cucumber which takes up Fe in a reduction based process (Strategy I) have been investigated. The identification of Fe microenvironments was carried out with (57)Fe Mössbauer spectroscopy and immunoblotting, whereas reductive washing and high-resolution microscopy was applied for the localization. In plants supplied with (57)Fe(III)-citrate, a transient presence of Fe-carboxylates in removable forms and the accumulation of partly removable, amorphous hydrous ferric oxide/hydroxyde have been identified in the apoplast and on the root surface, respectively. The latter may at least partly be the consequence of bacterial activity at the root surface. Ferritin accumulation did not occur at optimal Fe supply. Under Fe deficiency, highly soluble ferrous hexaaqua complex is transiently formed along with the accumulation of Fe-carboxylates, likely Fe-citrate. As (57)Fe-citrate is non-removable from the root samples of Fe deficient plants, the major site of accumulation is suggested to be the root xylem. Reductive washing results in another ferrous microenvironment remaining in the root apoplast, the Fe(II)-bipyridyl complex, which accounts for ~30 % of the total Fe content of the root samples treated for 10 min and rinsed with CaSO4 solution. When (57)Fe(III)-EDTA or (57)Fe(III)-EDDHA was applied as Fe-source higher soluble ferrous Fe accumulation was accompanied by a lower total Fe content, confirming that chelates are more efficient in maintaining soluble Fe in the medium while less stable natural complexes as Fe-citrate may perform better in Fe accumulation.

Fe-Impregnated Mineral Colloids for Peroxide Activation: Effects of Mineral Substrate and Fe Precursor

Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.

Ferrates(FeVI, FeV, and FeIV) oxidation of iodide: Formation of triiodide

The presence of iodide (I(-)) in water during disinfection and oxidative treatment of water is a potential health concern because of the formation of iodinated disinfection by-products (DBPs), which may be more toxic than chlorinated DBPs. The kinetics of the oxidation of I(-) by a greener oxidant, ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) was determined as a function of pH. The second-order rate constants (k, M(-1) s(-1)) decreased from 3.9 × 10(4) M(-1) s(-1) at pH 5.0 to 1.2 × 10(1) M(-1) s(-1) at pH 10.3. The kinetics results could be described by the reactivity of monoprotonated species of Fe(VI) (HFe(VI)O4(-)) with I(-). In excess I(-) concentration, triiodide (I3(-)) was formed and the stoichiometry of ∼1:1 ([Fe(VI)]:[I3(-)]) was found in both acidic and basic pH. Ferrate(V) (Fe(V)O4(3-), Fe(V)) and ferrate(IV) (Fe(VI)O4(4-), Fe(IV)) also showed the formation of I3(-) in presence of excess I(-). A mechanism of the formation of I3(-) is proposed, which is consistent with the observed stoichiometry of 1:1. The oxidative treatment of I(-) in water will be rapid (t1/2 = 0.6 s at pH 7.0 using 10 mg L(-1) K2FeO4). The implications of the results and their comparison with the oxidation of I(-) by conventional disinfectants/oxidants in water treatment are briefly discussed.

High-valent iron (FeVI, FeV, and FeIV) species in water: characterization and oxidative transformation of estrogenic hormones

Transformation of estrogenic hormones using high-valent iron species is described.

Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe

Transmitted human immunodeficiency virus drug resistance in Europe is stable at around 8%. The impact of baseline mutation patterns on susceptibility to antiretroviral drugs should be addressed using clinical guidelines. The impact on baseline susceptibility is largest for nonnucleoside reverse transcriptase inhibitors.

Background. Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001.

Methods. Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)–infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0.

Results. The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%–9.5%) in 2008–2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones.

Conclusions. Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

Direct evidence of Fe(V) and Fe(IV) intermediates during reduction of Fe(VI) to Fe(III): a nuclear forward scattering of synchrotron radiation approach

Identification of unstable high-valent iron species in electron transfer reactions of ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) has been an important challenge in advancing the understanding of the oxidative mechanisms of ferrates. This paper presents the first example of distinguishing various phases differing in the valence state of iron in the solid state reduction of Fe(VI) to Fe(III) oxides at 235 °C using hyperfine parameters, isomer shift and hyperfine magnetic field, obtained from nuclear forward scattering of synchrotron radiation (NFS). The NFS technique enables a fast data accumulation resulting in high time resolution of in situ experiments. The results suggest a reaction mechanism, involving Fe(V) and Fe(IV) species, in the thermal decomposition of K2FeO4 to KFeO2. The present study opens up an approach to exploring the unambiguous identification of Fe(VI), Fe(V), Fe(IV), and Fe(III) in electron-transfer reaction mechanisms of ferrates in solid and aqueous phase systems.

Photoanodes with Fully Controllable Texture: The Enhanced Water Splitting Efficiency of Thin Hematite Films Exhibiting Solely (110) Crystal Orientation

Hematite, α-Fe2O3, is considered as one of the most promising materials for sustainable hydrogen production via photoelectrochemical water splitting with a theoretical solar-to-hydrogen efficiency of 17%. However, the poor electrical conductivity of hematite is a substantial limitation reducing its efficiency in real experimental conditions. Despite of computing models suggesting that the electrical conductivity is extremely anisotropic, revealing up to 4 orders of magnitude higher electron transport with conduction along the (110) hematite crystal plane, synthetic approaches allowing the sole growth in that direction have not been reported yet. Here, we present a strategy for controlling the crystal orientation of very thin hematite films by adjusting energy of ion flux during advanced pulsed reactive magnetron sputtering technique. The texture and effect of the deposition mode on the film properties were monitored by XRD, conversion electron Mössbauer spectroscopy, XPS, SEM, AFM, PEC water splitting, IPCE, transient photocurrent measurements, and Mott-Schottky analysis. The precise control of the synthetic conditions allowed to fabricate hematite photoanodes exhibiting fully textured structures along (110) and (104) crystal planes with huge differences in photocurrents of 0.65 and 0.02 mA cm(-2) (both at 1.55 V versus RHE), respectively. The photocurrent registered for fully textured (110) film is among record values reported for thin planar films. Moreover, the developed fine-tuning of crystal orientation having a huge impact on the photoefficiency would induce further improvement of thin hematite films mainly if cation doping will be combined with the controllable texture.

[Toxoplasmosis in immunocompromised patients]

In humans, toxoplasmosis mostly occurs as a latent infection, but in immunocompromised individuals, the agent may reactivate and cause severe to life-threatening disease. HIV positive individuals and transplant recipients, in particular hematopoietic stem cell transplant and heart transplant recipients, are at highest risk. The disease most often affects the central nervous system but can involve any organ. Because of the alteration of the immune response in these patients, the serodiagnosis is not reliable and direct detection of the causative agent is needed--namely by microscopy and DNA PCR. If inadequately treated or left untreated, toxoplasmosis generally has a fatal prognosis in immunocompromised patients and therefore, the treatment must be started as early and energetically as possible. The gold standard both in the treatment of reactivation and secondary prophylaxis is the pyrimethamine-sulfadiazine combination while co-trimoxazole can be used in the primary prophylaxis for high-risk patients.

[Guidelines for caring for HIV-infected adults and postexposure prophylaxis for HIV infection]

The authors present instructions for providing antiretroviral therapy in the Czech health care system, based partly on recommendations from abroad and partly on their own experiences of caring for HIV /AIDS patients. The structure and content are similar to those in the 2010 edition, with new study outcomes and modern trends in treatment strategy being taken into consideration. The guidelines are based on systematic patient assessment and aimed at making an accurate diagnosis and formulating recommendations according to individual criteria. The document provides specific instructions for decisions on initiating antiretroviral therapy, selection of individual drugs, monitoring of treatment effect and adverse reactions, and reaction to potential therapy failure. Special attention is paid to administration of antiretroviral drugs to pregnant women and patients with comorbidities, especially tuberculosis, hepatitis or renal insufficiency. The new version includes procedures for postexposure prophylaxis for HIV infection. The guidelines are supplemented by a table summary of antiretroviral drugs. The presented document is to be used in negotiations between the association,state authorities and health care payers.

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite

Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3'-imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants (≈ 10(-2)s(-1)) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10(-8)-10(-6)s(-1)). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs.

First detection of Chlamydia trachomatis LGV biovar in the Czech Republic, 2010–2011

Binary file ES_Abstracts_Final_ECDC.txt matches

First detection of Chlamydia trachomatis LGV biovar in the Czech Republic, 2010-2011

We present four cases of proctitis in HIV-infected men having sex with men (MSM) living in the Czech Republic. The causative agent in all cases was the lymphogranuloma venereum (LGV) biovar of Chlamydia trachomatis. The spread of proctitis caused by C. trachomatis serovars L1–3 among MSM has been observed in several European countries, the United States and Canada since 2003. To our knowledge, no LGV cases in eastern Europe have been published to date.

History of viral suppression on combination antiretroviral therapy as a predictor of virological failure after a treatment change

OBJECTIVES

HIV-infected persons experience different patterns of viral suppression after initiating combination antiretroviral therapy (cART). The relationship between such differences and risk of virological failure after starting a new antiretroviral could help with patient monitoring strategies.

METHODS

A total of 1827 patients on cART starting at least one new antiretroviral from 1 January 2000 while maintaining a suppressed viral load were included in the analysis. Poisson regression analysis identified factors predictive of virological failure after baseline in addition to traditional demographic variables. Baseline was defined as the date of starting new antiretrovirals.

RESULTS

Four hundred and fifty-one patients (24.7%) experienced virological failure, with an incidence rate (IR) of 7.3 per 100 person-years of follow-up (PYFU) [95% confidence interval (CI) 6.7-8.0]. After adjustment, patients who had rebounded in the year prior to baseline had a 2.4-times higher rate of virological failure after baseline (95% CI 1.77-3.26; P<.0001), while there was no increased incidence in patients whose last viral rebound was >3 years prior to baseline [Incidence rate ratio (IRR) 1.06; 95% CI 0.75-1.50; P=0.73] compared with patients who had never virally rebounded. Patients had an 86% (95% CI 1.36-2.55; P<.0001), 53% (95% CI 1.06-2.04; P=0.02) and 5% (95% CI 0.80-1.38; P=0.72) higher virological failure rate after baseline if they were virally suppressed <50%, 50-70% and 70-90% of the time they were on cART prior to baseline, respectively, compared with those virally suppressed >90% of the time.

DISCUSSION

Intensive monitoring after a treatment switch is required in patients who have rebounded recently or have a low percentage of time suppressed while on cART. Consideration should be given to increasing the provision of adherence counselling.

[Diagnostic pitfalls of HIV-associated Kaposi's sarcoma]

Kaposi's sarcoma was one of the very first diseases which indicated the advent of the AIDS pandemic. Despite the marked fall in its occurrence thanks to the introduction of the cART, Kaposi's sarcoma remains the most frequent tumour in HIV-positive patients and still represents a major diagnostic and therapeutic problem. Particularly in the early stages both the macroscopic and histopathological picture of Kaposi's sarcoma may be very atypical, which can cause diagnostic difficulties right at the time when an early therapy may be most successful. In order to improve both the diagnostics and therapy of Kaposi's sarcoma, close collaboration between physicians taking care of HIV-positive patients--mainly infectologists, dermatologists and pathologists, is necessary.

Sol-gel-derived iron oxide thin films on silicon: surface properties and interfacial chemistry

Uniform high-quality iron oxide thin films can be formed from the spin coating of iron oxide/hydroxide sol-gels on a silicon substrate. Thermal processing of the films at temperatures of approximately 300 degrees C results in the transformation of films into a ternary layered structure with iron oxide, Fe(2)O(3), at the surface, characterized by Mossbauer spectroscopy, and reduced, metallic iron characterized by depth profiling of the surface by X-ray photoelectron spectroscopy as a function of Ar(+) etching. Imaging of the etched surface by scanning electron microscopy reveals two distinct regions at the interface, nanoparticles that are very iron-rich separated by an unstructured region that is somewhat less iron-rich. The results demonstrate a synthetic protocol for the spontaneous formaton of a ternary layered structure from a simple one-step preparation.

Antibody response of HIV-infected patients to latent, cerebral and recently acquired toxoplasmosis

The aim of this longitudinal study with 626 HIV-infected patients was to evaluate the capability of serological tests in diagnosing the presence of Toxoplasma gondii infection in HIV-infected patients, as well as the potential impact of various treatment regimes on serological results. Low IgG antibody levels and stable or declining titres predominated. IgM positivity occurred in ten patients (one seroconversion, seven latent, two cerebral toxoplasmosis). Complement fixation test (CFT) titres >or=1:32 imply that the relative risk of cerebral toxoplasmosis is 6.84 (95% confidence interval [CI] 1.44-32.5) but with a predictive value of only 14.0% (95% CI 5.3-27.9). Values of specific antibodies are not biassed by antiretroviral treatment and/or prophylaxis for toxoplasmosis, and the detection of specific antibodies is very useful in the identification of T. gondii infection in the HIV-infected population, but the role of serology in predicting the clinical manifestation of T. gondii infection is limited.

Neuroborreliosis in an HIV-1 positive patient

Simultaneous co-infections of Borrelia burgdorferi sensu lato and HIV-1 are rare events, with only six published cases. A case of acute neuroborreliosis with facial palsy, meningoradiculitis (Bannwarth's syndrome) in an HIV-1 positive individual is described. Diagnosis was confirmed by Western immunoblot analysis of serum and CSF and by proof of intrathecal production of antibodies against B. garinii. The patient was successfully treated with cefotaxime. In all published HIV+ cases, the course of borreliosis did not differ from that of the HIV negative population and the prognosis in properly treated patients was good.

[Recommendation for diagnostics and therapy of toxoplasmosis in persons with HIV infection]

Reactivation of latent toxoplasmosis is a serious complication in patients with deep immunodeficiency, but the disease has a good prognosis if early diagnosed and effectively treated. Definitive etiologic proof of the reactivation may be difficult and thus an empiric method (therapeutic trial) is used for confirmation of the diagnosis in clinical practice. The preferred therapy is a combination of pyrimethamine + sulfadiazine.

[Analysis of a group of HIV positive women who gave birth in the Czech Republic]

OBJECTIVE

An analysis of HIV positive women who gave birth between 1st January 1985 to 31st December 2006 in the Czech Republic.

SUBJECT

A retrospective descriptive analysis.

SETTING

Teaching Hospital Bulovka, 1st Faculty of Medicine, Charles University, Prague.

SUBJECT AND METHODS

The study included HIV positive women that gave birth between 1st January 1985 to 31st December 2006 at Bulovka hospital. The group of 62 HIV positive women (including 7 secundiparae) gave birth to 71 new-borns (twice twins). The deliveries were performed by C-section. We interrupted breast-feeding by all these women.

RESULTS

All new-borns were born alive, no one had Apgar score less than 7 at five minutes. No congenital disorders were found. Three new-borns were transfered to Intensive care unit for new-born babies, two due to dysmaturity and one due to abstinence syndrome. 3 new-borns out of total 71 new-borns were HIV positive (4.2%).

CONCLUSION

Routine prenatal screening for HIV and high-quality cooperation between obstetricians and infection control doctors are the basic condition of low rate of vertical trasmission HIV infection in the Czech Republic.

Mössbauer Characterization and in Situ Monitoring of Thermal Decomposition of Potassium Ferrate(VI), K2FeO4 in Static Air Conditions

Solid orthorhombic crystals of potassium ferrate(VI) (K(2)FeO(4)) of a high-chemical purity (>99.0%) were characterized by low-temperature (1.5-5 K), high-temperature (463-863 K), and in-field (1.5 K/3 T) Mössbauer spectroscopy. Potassium ferrate(VI) reveals a Néel magnetic transition temperature (TN) of approximately 3.8 K and a saturation hyperfine magnetic field of 13.8 T at 1.5 K. Spectral line intensities recorded below TN in an external magnetic field of 3 T manifest a perfect antiferromagnetic ordering. For the in situ monitoring of the thermal behavior of K(2)FeO(4), high-temperature Mössbauer data were combined with those obtained from thermogravimetry, differential scanning calorimetry, and variable-temperature X-ray diffraction measurements. Such in situ approach allowed the identification of the reaction products and intermediates and yielded the first experimental evidence for the participation of CO2 in the decomposition process. As the primary conversion products, KFeO(2) and two potassium oxides in equivalent molar ratio, KO2 and K(2)O, were suggested. However, the KO2 phase is detectable with difficulty as it reacts very quickly with CO2 from air resulting in the formation of K(2)CO(3). The presented decomposition model is consistent with thermogravimetric data giving the mass loss of 8.0%, which corresponds to the participation of 1/6 mol of CO2 and liberation of 3/4 mol of O2 per 1 mol of K(2)FeO(4) (K(2)FeO(4) + 1/6CO2 --> KFeO(2) + 1/3K(2)O + 1/6K(2)CO(3) + 3/4O2). An explanation of the multistage reaction mechanism has an important practical impact for the optimization of the solid-state synthesis of potassium ferrate(VI).

Amorphous Iron(III) OxideA Review

The syntheses of amorphous Fe(2)O(3) nanoparticles of varying size and morphology, their magnetic properties, crystallization mechanism, and applications are reviewed herein. The synthetic routes are classified according to the nature of the sample (powders, nanocomposites, films, coated particles). The contributions of various experimental techniques to the characterization of an amorphous Fe(2)O(3) phase are considered in this review, including some key experimental markers, allowing its distinction from nanocrystalline "X-ray amorphous" polymorphs (maghemite, hematite). We discuss the thermally induced crystallization mechanisms depending on transformation temperature, atmosphere, and the size of the amorphous particles that predetermine the structure of the primarily formed crystalline polymorph. The controversial description of the magnetic behavior, including an interpretation of the low-temperature and in-field Mössbauer spectra, is analyzed.

Evaluation of a commercial IgE ELISA in comparison with IgA and IgM ELISAs, IgG avidity assay and complement fixation for the diagnosis of acute toxoplasmosis

A panel of sera from patients with known case histories representative of acute toxoplasmosis (primarily lymphadenopathy, n = 106), latent toxoplasmosis (asymptomatic, n = 368) and negative samples (n = 54) was used to evaluate the capacity of five serological tests to differentiate among patients with acute or latent toxoplasmosis and non-infected individuals. Positive IgA, IgE and IgM ELISA results and low IgG avidity and complement fixation test (CFT) titres of >or=256 were considered to be indicative of acute toxoplasmosis. The most sensitive methods were IgM ELISA (98.1%) and CFT (97.1%), albeit with low specificity (65.0% and 64.5%, respectively) and positive predictive values (43.3% and 42.7%, respectively). IgG avidity assay and IgE ELISA had the highest specificity (97.7% and 91.7%, respectively) and the highest positive predictive values (89.4% and 75.6%, respectively). The best association between serological results and clinical findings was obtained with IgE ELISA (86%, as expressed via Youden's index). In a subset of 259 samples categorised by the period between the onset of clinical symptoms and sampling, >50% of patients had enlarged lymph nodes for <4 months, despite a broad range of differences. However, IgM remained positive for 12-18 months, IgA for 6-9 months and IgE for 4-6 months. IgG avidity remained low for a maximum of 4 months, after which avidity increased despite the persistence of enlarged lymph nodes and a positive IgE assay. Detection of IgE appears to be a highly specific test for confirming the acute nature of Toxoplasma infections that have been detected by other sensitive methods.