Wireless phone use in childhood and adolescence and neuroepithelial brain tumours: Results from the international MOBI-Kids study.

In recent decades, the possibility that use of mobile communicating devices, particularly wireless (mobile and cordless) phones, may increase brain tumour risk, has been a concern, particularly given the considerable increase in their use by young people. MOBI-Kids, a 14-country (Australia, Austria, Canada, France, Germany, Greece, India, Israel, Italy, Japan, Korea, the Netherlands, New Zealand, Spain) case-control study, was conducted to evaluate whether wireless phone use (and particularly resulting exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF)) increases risk of brain tumours in young people. Between 2010 and 2015, the study recruited 899 people with brain tumours aged 10 to 24 years old and 1,910 controls (operated for appendicitis) matched to the cases on date of diagnosis, study region and age. Participation rates were 72% for cases and 54% for controls. The mean ages of cases and controls were 16.5 and 16.6 years, respectively; 57% were males. The vast majority of study participants were wireless phones users, even in the youngest age group, and the study included substantial numbers of long-term (over 10 years) users: 22% overall, 51% in the 20-24-year-olds. Most tumours were of the neuroepithelial type (NBT; n = 671), mainly glioma. The odds ratios (OR) of NBT appeared to decrease with increasing time since start of use of wireless phones, cumulative number of calls and cumulative call time, particularly in the 15-19 years old age group. A decreasing trend in ORs was also observed with increasing estimated cumulative RF specific energy and ELF induced current density at the location of the tumour. Further analyses suggest that the large number of ORs below 1 in this study is unlikely to represent an unknown causal preventive effect of mobile phone exposure: they can be at least partially explained by differential recall by proxies and prodromal symptoms affecting phone use before diagnosis of the cases. We cannot rule out, however, residual confounding from sources we did not measure. Overall, our study provides no evidence of a causal association between wireless phone use and brain tumours in young people. However, the sources of bias summarised above prevent us from ruling out a small increased risk.

Multisensor hyperspectral imaging approach for the microchemical analysis of ultramarine blue pigments.

This work presents a multisensor hyperspectral approach for the characterization of ultramarine blue, a valuable historical pigment, at the microscopic scale combining the information of four analytical techniques at the elemental and molecular levels. The hyperspectral images collected were combined in a single hypercube, where the pixels of the various spectral components are aligned on top of each other. Selected spectral descriptors have been defined to reduce data dimensionality before applying unsupervised chemometric data analysis approaches. Lazurite, responsible for the blue color of the pigment, was detected as the major mineral phase present in synthetic and good quality pigments. Impurities like pyrite were detected in lower quality samples, although the clear identification of other mineral phases with silicate basis was more difficult. There is no correlation between the spatial distribution of the bands arising in the Raman spectra of natural samples in the region 1200-1850 cm-1 and any of the transition metals or rare earth elements (REE). With this information, the previous hypothesis (based on bulk analysis) attributing these bands to luminescence emissions due to impurities of these elements must be revised. We propose the consideration of CO2 molecules trapped in the cages of the aluminosilicate structure of sodalite-type. Additionally, correlation between certain Raman features and the combined presence of Ca, P, and REE, in particular Nd, was detected for the lowest quality pigment. Our results highlight the usefulness of fusing chemical images obtained via different imaging techniques to obtain relevant information on chemical structure and properties.

Multicomponent diffusion in ionic crystals: theoretical model and application to combined tracer- and interdiffusion in alkali feldspar.

We present a model for multicomponent diffusion in ionic crystals. The model accounts for vacancy-mediated diffusion on a sub-lattice and for diffusion due to binary exchange of different ionic species without involvement of vacancies on the same sub-lattice. The diffusive flux of a specific ionic species depends on the self-diffusion coefficients, on the diffusion coefficients related to the binary exchanges, and on the site fractions of all ionic species. The model delivers explicit expressions for these dependencies, which lead to a set of coupled non-linear diffusion equations. We applied the model to diffusion of 23 Na, 39 K, and 41 K in alkali feldspar. To this end, gem-quality crystals of alkali feldspar were used together with 41 K doped KCl salt as diffusion couples, which were annealed at temperatures between 800 ∘ and 950 ∘ C. Concentration-distance data for 23 Na, 39 K, and 41 K were obtained by Time of Flight Secondary Ion Mass Spectrometry. Over the entire investigated temperature range the Na self-diffusion coefficient is by a factor of ≥ 500 higher than the K self-diffusion coefficient. Diffusion mediated by binary 39 K- 41 K exchange is required for obtaining satisfactory fits of the model curves to the experimental data, and the respective kinetic coefficient is well constrained.

Resistive states in strontium titanate thin films: Bias effects and mechanisms at high and low temperature.

A study on charge transport properties of thin film Fe-doped SrTiO3 epitaxially grown on Nb-doped SrTiO3 is reported. Electric measurements between 350 °C and 750 °C show a transition from predominant ionic to electronic conduction and lower conductivity of the thin films compared to the bulk of polycrystalline samples. Defect chemical changes at elevated temperature were investigated by applying a bias voltage. A model is described which successfully predicts additional features such as inductive loops or extra semicircles measureable by impedance spectroscopy as well as the complicated time dependence of electric DC-measurements. With this model it is also possible to calculate the negligibly small ionic conductivity next to the dominating electronic conductivity in the high temperature regime. The ionic conductivity is referenced by oxygen isotope depth profiling. Changes of resistive states in Fe-doped SrTiO3 thin films at high temperature and moderate fields are compared to room temperature resistive switching phenomena at high electric fields. A conductive filament based switching process is observed at room temperature, and the capability for forming such filaments and their electric properties is further analysed using microelectrodes.

The challenges posed by climate change to successful ageing.

Ever since the 2003 heat wave that caused 70,000 heat deaths, the dramatic consequences of climate change and rising temperatures in Europe have become an intensively researched topic. During heat waves, the older urban adult population is at highest risk. The STOPHOT project is the first investigation in Austria to establish a comprehensive knowledge base on heat perception, awareness of heat risks and adaptive/coping behaviours among older adults. The main research questions include: (1) Does climate change endanger the chances of successful ageing in urban areas? (2) How do age, social inequalities and the living environment intersect with environmental stressors in affecting successful ageing? (3) Which heat adaption strategies do older adults deploy and to what extent can they mediate heat stress in an effort to increase chances of successful ageing under the conditions of climate change? The results indicate that climate change and rising temperatures are in fact one important determinant of whether and how an older person can maintain well-being in later life. Older adults (> 65 years) with a low socio-economic status and poor health conditions, who tend to be socially isolated, are most at risk. However, no 'heat island effect' of the residential environment could be found. How much a person suffers from heat stress is highly dependent on the adaption strategies deployed. Adaption strategies of older urban residents mostly centred on body-related measures, such as drinking more or wearing lighter clothes, and indoor-centred measures, particularly avoiding the outdoors.

Urinary levoglucosan levels in Austrian communities differing in agrarian quota.

Levoglucosan is a sugar anhydride produced by combustion of carbohydrates. In ambient monitoring it serves as an indicator for wood smoke. Its use in human biomonitoring, however, is not yet widespread. This study investigated whether levoglucosan in urine is a suitable biomarker for regional differences in wood smoke exposure in the winter season. Within the first Austrian biomonitoring survey, pooled urine samples from mothers as well as children of five communities of different size (two-stage random stratified sampling) were analysed by HPLC. As an indicator of exposure to polycyclic aromatic hydrocarbons (PAH) that are also prevalent in wood smoke, 1-hydroxypyrene was determined. In each town levoglucosan was found in higher levels in the pooled children's samples than in the pooled mothers' samples. It correlated well with the agrarian quota. 1-Hydroxypyrene concentrations were higher in areas with higher population density. Correlation of urinary levoglucosan concentrations with the agrarian quota may be explained by higher wood smoke exposure in communities with higher agrarian quota. To our knowledge this study is the first investigation on this issue in Europe. It indicates that human biomonitoring of levoglucosan may be suitable to detect differences in regional exposure to wood smoke.

Characterisation of sputter deposited niobium and boron interlayer in the copper-diamond system.

In most metal matrix composites (MMCs) interfaces are decisive but hard to manipulate. Especially copper-carbon composites can exhibit excellent mechanical and thermal properties only if the Cu/C interface is modified by an optimised interlayer. Due to the excellent thermal conductivity and mechanical stability of diamond this form of carbon is preferred as reinforcement in heat sink materials (copper-diamond composite) which are often subjected to severe thermal and mechanical loads. In the present case niobium and boron interlayers of various thicknesses were deposited on diamond and vitreous carbon substrates by magnetron sputter deposition. After the coverage of all samples by a copper film, a part of the samples was subjected to heat treatment for 30 min at 800 °C under high vacuum (HV) to simulate the thermal conditions during the production of the composite material by uniaxial hot pressing. De-wetting during heat treatment leads to the formation of holes or humps in the Cu coating. This effect was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A comparison of time-of-flight secondary ion mass spectroscopy (TOF SIMS) profiles of heat treated samples with those of as deposited ones showed the influence of interdiffusion during the heating process. Diffusion behaviour and chemical composition of the interface were also studied by cross sectional transmission electron microscopy (X-TEM) investigations using focused ion beam (FIB) cut samples. The thermal contact resistance (TCR) of the interface was calculated from results obtained from modulated infrared radiometry (IR). Thin interlayers suppressed de-wetting most effectively and consequently the TCR at the Cu-diamond interface was found to decrease. Therefore they are promising candidates for optimising the Cu-diamond interface.

[Lung function of dust-exposed workers]. / Lungenfunktion staubexponierter Arbeitnehmer.

Workers exposed to dust have to undergo medical check-ups every 2 years including lung function testing. Here we report on the routine lung function data (FVC, FEV1, MEF50) of 994 workers from Austria. Lung function data were compared to the Austrian standard values that are based on routine testing of healthy volunteers. For all parameters the workers' values were significantly poorer than the Austrian standards (FVC: -0.4 l; FEV1: -0.5 l; MEF50: -0.9 l/s). The difference from the standard increased with increasing duration of the dust exposure. This increase was significant for the total group for MEF50 even after controlling for smoking. About half of the workers were exposed to quartz dust and had poorer lung function values (p = 0.02 for MEF50) than the other workers. Smoking significantly reduced all 3 lung function parameters with a significant interaction between strong smoking (compared to non-smokers) and quartz exposure (compared to all other exposures). Current Austrian limit values are not protective against chronic damage of the respiratory system. The combined impact of cigarette smoke and high concentration of mineral dust (quartz) is especially dangerous.

Characterization of the mechanical and thermal interface of copper films on carbon substrates modified by boron based interlayers.

The manipulation of mechanical and thermal interfaces is essential for the design of modern composites. Amongst these are copper carbon composites which can exhibit excellent heat conductivities if the Cu/C interface is affected by a suitable interlayer to minimize the Thermal Contact Resistance (TCR) and to maximize the adhesion strength between Cu and C.In this paper we report on the effect of boron based interlayers on wetting, mechanical adhesion and on the TCR of Cu coatings deposited on glassy carbon substrates by magnetron sputtering. The interlayers were 5 nm thick and consisted of pure B and B with additions of the carbide forming metals Mo, Ti and Cr in the range of 5 at.% relative to B. The interlayers were deposited by RF magnetron sputtering from either a pure B target or from a composite target. The interlayer composition was checked by Auger Electron Spectroscopy and found to be homogenous within the whole film.The system C-substrate/interlayer/Cu coating was characterized in as deposited samples and samples heat treated for 30 min at 800 °C under High Vacuum (HV), which mimics typical hot pressing parameters during composite formation. Material transport during heat treatment was investigated by Secondary Ion Mass Spectroscopy (SIMS). The de-wetting and hole formation in the Cu coating upon heat treatment were studied by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The adhesion of the Cu coating was evaluated by mechanical pull-off testing. The TCR was assessed by infrared photothermal radiometry (PTR). A correlation between the adhesion strength and the value of the TCR which was measured by PTR was determined for as deposited as well as for heat treated samples.

Measurement of 18O tracer diffusion coefficients in thin yttria stabilized zirconia films.

In this paper we present a method to measure oxygen tracer diffusion coefficients in thin ion conducting films without being limited by slow oxygen incorporation kinetics. The method is based on a two step process. In the first step a substantial amount of 18O tracer is locally incorporated for example into an yttria stabilized zirconia (YSZ) layer at low temperatures with the aid of an electric current, thus overcoming slow thermal oxygen exchange while still limiting lateral diffusion to a minimum. In the second step controlled diffusion takes place at elevated temperatures in ultra high vacuum (UHV) to impede loss of tracer due to oxygen exchange at the film surface. In this second step the surface of the thin film may additionally be modified compared to the oxygen incorporation step. This allows to easily investigate effects of interfaces on ion transport. The achieved in-plane concentration profiles are then measured by secondary ion mass spectrometry (SIMS). Comparison with electrical measurements on YSZ thin films proves the applicability of the method.

Higher blood concentrations of synthetic musks in women above fifty years than in younger women.

Synthetic musk compounds are widely used as fragrance ingredients in many consumer products. Little is known about their accumulation in humans and especially in older persons. In this study, we determined concentrations of 11 synthetic musks in women above fifty years and compared the results with earlier results from samples of young females. Blood was taken from 53 women above 50 years of age, visiting outpatients of the Department of Angiology at the Hanusch-Krankenhaus in Vienna, Austria. The used analytical methods consist of an extraction and clean-up step and a chromatographic analysis by GC/MS. Tonalide-D3 was used as recovery standard in all samples. Hexachlorobenzene (13)C(6) was used as internal standard. Study participants also completed a questionnaire on the use of cosmetics, about nutrition and other life-style aspects. The two substances which could be detected in higher percentages of the blood plasma samples were galaxolide (89 percent, maximum concentration 6900 ng/L) and musk xylene (62 percent, maximum concentration 190 ng/L). Regression analysis revealed a significant association of galaxolide concentration with frequent use of perfumes, deodorants and shampoos. Frequent use of soaps and fabric softener was associated with higher plasma concentrations of musk xylene. Nutrition habits, skin type, body mass index or surface area were not related to plasma concentration of these musk compounds. From the study group investigated older persons showed higher plasma concentrations. These findings could be due to the higher use of lotions and crèmes on face and hands and a more frequent use of skin care products because older persons reported more frequently dry skin. In addition, physiological aging related changes might be responsible for higher dermal absorption of synthetic musks. These results indicate that more focus on aging tissues is needed.

Synthetic musks in blood of healthy young adults: relationship to cosmetics use.

Production of polycyclic musk compounds is increasing accompanied by a decline in nitro musk production. Although it can be assumed that due to this reduction nitro musks are less prevalent in human body fluids, there are no data available from the last decade. This study examined the concentrations of five nitro musks and six polycyclic musks in blood samples from young healthy volunteers. Blood was taken from 100 healthy students of the Medical University of Vienna. The lipophilic fraction was extracted and after purification analyzed by GC-MS. Study participants also completed a questionnaire on the use of cosmetics, about nutrition and other life-style aspects. Highest percentages of synthetic musks in blood plasma samples were found for galaxolide (91%, median 420 ng L(-1)) and musk xylene (79%, median 11 ng L(-1)). Both musk ketone and tonalide were found in 17%. In two cases musk ambrette was detected. In a multivariate approach only younger age, use of lotion and perfumes did significantly predict blood concentrations of polycyclic musks. For nitro musks except body surface area no significant predictor could be found. High percentage of the population is still exposed to nitro musk compounds although blood concentrations of nitro musks are generally lower than those of polycyclic musks. Compared to earlier investigations performed in the 1990s nitro musks were detected in lower percentages and concentrations. There seems to be no dominant source of nitro musk uptake although relationship to body surface area indicates cosmetic products applied to the skin as the likely origin of plasma concentrations.

TOF-SIMS depth profiling and element mapping on oxidized AlCrVN hard coatings.

V-alloyed AlCrN hard coatings were deposited on silicon wafers (Si (100)) by reactive arc evaporation in a commercial coating system at 500 degrees C for 10 min, resulting in a coating thickness of approximately 500 nm. The chemical composition of the stoichiometric coatings is constant at approximately Al(0.70)Cr(0.05)V(0.25)N regardless of the applied bias voltage during deposition. Coatings synthesized at a low bias of -40 V show a dual-phase structure (hexagonal close-packed and face-centered cubic (fcc)), whereas coatings deposited at a high bias of -150 V have a metastable single-phase structure (face-centered cubic). All samples were oxidized for 15 min under 20 mbar O(2) atmosphere and at four different temperatures (550, 600, 650, and 700 degrees C). The oxidized coatings were subject to depth profiling and element mapping by a time of flight secondary ion mass spectrometry instrument, equipped with a Bi-cluster analysis gun and Cs(+)-sputter gun. The evaluation of the in-depth distribution of several elements and species points out distinctive differences in the oxidation behavior of the two different coatings, whereas element mapping shows the formation of islands made of oxidized vanadium and aluminum species as the top-most layer of the single-phase (fcc) coating at temperatures above 650 degrees C.

TOF-SIMS investigations on weathered silver surfaces.

Silver-coated quartz crystal microbalance (QCM) disks were treated under different environmental conditions (including changes in parameters such as relative humidity (%RH) and SO(2)/H(2)S content) in atmospheres of synthetic air and pure N(2) for 24 h in a weathering chamber. The corroded surfaces were subjected to depth profiling by a time of flight (TOF) secondary ion mass spectrometry (SIMS) instrument, equipped with a Bi(+) analysis gun and Cs(+) sputter gun. The evaluation of the in-depth distribution of several elements and species provides evidence for the formation of a corrosion layer containing Ag(2)SO(3), even in the absence of oxidizing agents, such as H(2)O(2) or NO(2). Furthermore it could be elucidated that the thickness of the formed Ag(2)SO(3) layer does not depend on the SO(2) concentration but rather on the humidity and oxygen content of the ambient atmosphere. In weathering experiments in atmospheres composed of synthetic air, humidity, and H(2)S, the presence of different oxygen species (surface and bulk) and silver sulfide could be detected by TOF-SIMS depth profiling experiments. The obtained results for both acidifying gases are in good correlation with the corresponding tapping mode atomic force microscopy (TM-AFM) investigations and in situ QCM measurements.

Persistent sciatic artery: an uncommon cause of intermittent claudication.

Persistent sciatic artery (PSA) is a rarely seen variation of the lower limb vessels. Anatomically the PSA is the continuation of internal iliac arteries. It follows the sciatic nerve from the sciatic foramen to the level of the knee. We report our experience with conservative therapy in a patient with complete occlusion of a PSA. A 54-year-old man with typical symptoms of intermittent claudication on the left limb was referred to our Department. After clinical examination Doppler and duplex sonography were performed. Angiography showed bilateral PSA. On the left side the PSA was occluded. The patient received 20 intravenous courses of prostaglandin E1 for 4 weeks, followed by oral anticoagulation with phenprocoumon for life (INR: 2.5-3.5). After 3 years therapy he does not show any typical symptoms of intermittent claudication or limb ischemia. This case shows that conservative therapy may be effective. However, it has to be emphasised that this approach requires frequent clinical and duplex sonography follow-up every 3 to 6 months with oral anticoagulation.

Subjective symptoms, sleeping problems, and cognitive performance in subjects living near mobile phone base stations.

BACKGROUND: The erection of mobile telephone base stations in inhabited areas has raised concerns about possible health effects caused by emitted microwaves. METHODS: In a cross-sectional study of randomly selected inhabitants living in urban and rural areas for more than one year near to 10 selected base stations, 365 subjects were investigated. Several cognitive tests were performed, and wellbeing and sleep quality were assessed. Field strength of high-frequency electromagnetic fields (HF-EMF) was measured in the bedrooms of 336 households. RESULTS: Total HF-EMF and exposure related to mobile telecommunication were far below recommended levels (max. 4.1 mW/m2). Distance from antennae was 24-600 m in the rural area and 20-250 m in the urban area. Average power density was slightly higher in the rural area (0.05 mW/m2) than in the urban area (0.02 mW/m2). Despite the influence of confounding variables, including fear of adverse effects from exposure to HF-EMF from the base station, there was a significant relation of some symptoms to measured power density; this was highest for headaches. Perceptual speed increased, while accuracy decreased insignificantly with increasing exposure levels. There was no significant effect on sleep quality. CONCLUSION: Despite very low exposure to HF-EMF, effects on wellbeing and performance cannot be ruled out, as shown by recently obtained experimental results; however, mechanisms of action at these low levels are unknown.

Low levels of air pollution induce changes of lung function in a panel of schoolchildren.

In search of sensitive screening parameters for assessing acute effects of ambient air pollutants in young schoolchildren, the impact of 8-h average air pollution before lung function testing was investigated by oscillatory measurements of resistance and spirometry with flow-volume loops. At a central elementary school in Linz, the capital of Upper Austria, 163 children aged 7-10 yrs underwent repeated examinations at the same time of day during 1 school year, yielding a total of 11-12 lung function tests per child. Associations to mass concentrations of particulate matter and nitrogen dioxide (NO(2)) measured continuously at a nearby monitoring station were tested, applying the Generalised Estimating Equations model. Reductions per 10 microg.m(-3) (both for particles and for NO(2)) were in the magnitude of 1% for most lung function parameters. The most sensitive indicator for acute effects of combustion-related pollutants was a change in maximal expiratory flow in small airways. NO(2) at concentrations below current standards reduced (in the multipollutant model) the forced expiratory volume in one second by 1.01%, maximal instantaneous forced flow when 50% of the forced vital capacity remains to be exhaled (MEF(50%)) by 1.99% and MEF(25%) by 1.96%. Peripheral resistance increased by 1.03% per 10 microg.m(-3) of particulate matter with a 50% cut-off aerodynamic diameter of 2.5 mum (PM(2.5)). Resistance is less influenced by the child's cooperation and should be utilised more often in environmental epidemiology when screening for early signs of small airway dysfunction from urban air pollution, but cannot replace the measurement of MEF(50%) and MEF(25%). In the basic model, the reduction of these parameters per 10 microg.m(-3) was highest for NO(2), followed by PM(1), PM(2.5) and PM(10), while exposure to coarse dust (PM(10)-PM(2.5)) did not change end-expiratory flow significantly. All acute effects of urban air pollution found on the lung function of healthy pupils were evident at levels below current European limit values for nitrogen dioxide. Thus, planned reduction of nitrogen dioxide emission (Euro 5; vehicles that comply with the emission limits as defined in Directive 99/96/EC) of 20% in 2010 would seem to be insufficient.

Quantitative analysis of the Ge concentration in a SiGe quantum well: comparison of low-energy RBS and SIMS measurements.

The germanium concentration and the position and thickness of the quantum well in molecular beam epitaxy (MBE)-grown SiGe were quantitatively analyzed via low-energy Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS). In these samples, the concentrations of Si and Ge were assumed to be constant, except for the quantum well, where the germanium concentration was lower. The thickness of the analyzed quantum well was about 12 nm and it was situated at a depth of about 60 nm below the surface. A dip showed up in the RBS spectra due to the lower germanium concentration in the quantum well, and this was evaluated. Good depth resolution was required in order to obtain quantitative results, and this was obtained by choosing a primary energy of 500 keV and a tilt angle of 51 degrees with respect to the surface normal. Quantitative information was deduced from the raw data by comparing it with SIMNRA simulated spectra. The SIMS measurements were performed with oxygen primary ions. Given the response function of the SIMS instrument (the SIMS depth profile of the germanium delta (delta) layer), and using the forward convolution (point-to-point convolution) model, it is possible to determine the germanium concentration and the thickness of the analyzed quantum well from the raw SIMS data. The aim of this work was to compare the results obtained via RBS and SIMS and to show their potential for use in the semiconductor and microelectronics industry. The detection of trace elements (here the doping element antimony) that could not be evaluated with RBS in low-energy mode is also demonstrated using SIMS instead.

The soluble pool of HLA-G produced by human trophoblasts does not include detectable levels of the intron 4-containing HLA-G5 and HLA-G6 isoforms.

In the context of implantation and pregnancy, several immunomodulating functions have been attributed to the different HLA-G isoforms. Increasing attention is now being addressed to the actively secreted soluble forms, because they might have a systemic function or could be useful as diagnostic tools. However, the cellular source of secretion, even during pregnancy, where HLA-G expression level is known to be highest, is still under debate. To elucidate the conflicting results, we investigated the isoform distribution in human first trimester and term placentas in situ and in vitro. Results obtained by applying immunohistochemistry, western blot, enzyme-linked immunosorbent assay (ELISA) and RT-PCR show that (1) all of the alpha1 domain-containing HLA-G isoforms are restrictedly expressed in the extravillous cytotrophoblasts (EVCTs) and very few first-trimester syncytiotrophoblasts, which directly cover cell columns, whereas mesenchymal cells of the villous chorion do not express HLA-G; (2) as demonstrated in western blots, trophoblasts express only the HLA-G1 isoform; (3) HLA-G5 and -G6 transcripts could be detected in human term placenta and isolated first-trimester trophoblasts but levels are extremely low; and (4) conditioned media of primary first-trimester trophoblasts, and the chorion laeve-derived trophoblastic cell line AC1-M59 do contain HLA-G1 fragments shed from the cell surface. Our data provide substantial evidence that none of the intron 4-containing isoforms, the so-called actively secreted, soluble HLA-G5 or -G6, are produced by human trophoblasts in situ or in vitro.