Gestational Exposure to Sodium Valproate Disrupts Fasciculation of the Mesotelencephalic Dopaminergic Tract, With a Selective Reduction of Dopaminergic Output From the Ventral Tegmental Area.

Gestational exposure to valproic acid (VPA) is known to cause behavioral deficits of sociability, matching similar alterations in human autism spectrum disorder (ASD). Available data are scarce on the neuromorphological changes in VPA-exposed animals. Here, we focused on alterations of the dopaminergic system, which is implicated in motivation and reward, with relevance to social cohesion. Whole brains from 7-day-old mice born to mothers given a single injection of VPA (400 mg/kg b.wt.) on E13.5 were immunostained against tyrosine hydroxylase (TH). They were scanned using the iDISCO method with a laser light-sheet microscope, and the reconstructed images were analyzed in 3D for quantitative morphometry. A marked reduction of mesotelencephalic (MT) axonal fascicles together with a widening of the MT tract were observed in VPA treated mice, while other major brain tracts appeared anatomically intact. We also found a reduction in the abundance of dopaminergic ventral tegmental (VTA) neurons, accompanied by diminished tissue level of DA in ventrobasal telencephalic regions (including the nucleus accumbens (NAc), olfactory tubercle, BST, substantia innominata). Such a reduction of DA was not observed in the non-limbic caudate-putamen. Conversely, the abundance of TH+ cells in the substantia nigra (SN) was increased, presumably due to a compensatory mechanism or to an altered distribution of TH+ neurons occupying the SN and the VTA. The findings suggest that defasciculation of the MT tract and neuronal loss in VTA, followed by diminished dopaminergic input to the ventrobasal telencephalon at a critical time point of embryonic development (E13-E14) may hinder the patterning of certain brain centers underlying decision making and sociability.

Valproate Exposure in ovo Attenuates the Acquisition of Social Preferences of Young Post-hatch Domestic Chicks.

Embryonic exposure to valproic acid (VPA) is known to produce sociability deficits, resembling human autistic phenotypes, in several vertebrate species. Animals living in groups prefer the proximity of peers and have the ability to perceive and to respond to social signals for modifying behavior. Chicks of Galliform birds, known to display early preference behaviors, have been used extensively for adaptive learning studies. Young precocial birds seem to be useful models also for studying the effect of embryonic VPA treatment. Here, domestic chicken eggs were injected with sodium valproate (200 µl of 35 µmol/L solution) or with vehicle (distilled water) on the 14th day of incubation. After hatching, the chicks were tested for one-trial passive avoidance learning at day 1, vocalization due to isolation as a measure of stress level (day 2), approach preference to large versus small groups of age-matched conspecifics (day 5), and to those with normal versus blurred head features (day 7). In addition, we tested the preference of birds to conspecifics reared in group versus those reared in isolation (day 9), as well as the preference of chicks to familiar versus non-familiar conspecifics (day 21). Our findings confirm previous reports concerning an adverse effect of VPA on embryonic development, including a tendency for aborted or delayed hatching and, occasionally, for locomotor disorders in a small percentage of birds (eliminated from later studies). Otherwise, VPA treatment did not impair motor activity or distress level. Memory formation for the aversive stimulus and discrimination of colors were not impaired by VPA treatment either. Innate social predispositions manifested in approach preferences for the larger target group or for the birds with natural facial features remained unaffected by VPA exposure. The most prominent finding was attenuation of social exploration in VPA-exposed birds (expressed as the frequency of positional switches between two stimulus chicks after the first choice), followed by a deficit in the recognition of familiar conspecifics, unfolding at the end of the third week. Social exploration and recognition of familiar individuals are the key elements impaired at this stage. The results underline the importance of early social exploration in ASD.

Gestational Exposure to the Synthetic Cathinone Methylenedioxypyrovalerone Results in Reduced Maternal Care and Behavioral Alterations in Mouse Pups.

The member of synthetic cathinone family, methylenedioxypyrovalerone (MDPV), is a frequently used psychoactive drug of abuse. The objective of our study was to determine the effect of MDPV (administered from the 8th to the 14th day of gestation) on the behavior of neonatal and adolescent mice, as well as its effect on maternal care. We measured maternal care (pup retrieval test, nest building), locomotor activity (open field test), and motor coordination (grip strength test) of dams, whereas on pups we examined locomotor activity at postnatal day 7 and day 21 (open field test) and motor coordination on day 21 (grip strength test). On fresh-frozen brain samples of the dams we examined the expression of two important peptides implicated in the regulation of maternal behavior and lactation: tuberoinfundibular peptide 39 (TIP39) mRNA in the thalamic posterior intralaminar complex, and amylin mRNA in the medial preoptic nucleus. We detected decreased birth rate and survival of offspring, and reduced maternal care in the drug-treated animals, whereas there was no difference between the motility of treated and control mothers. Locomotor activity of the pups was increased in the MDPV treated group both at 7 and 21 days of age, while motor coordination was unaffected by MDPV treatment. TIP39 and amylin were detected in their typical location but failed to show a significant difference of expression between the drug-treated and control groups. The results suggest that chronic systemic administration of the cathinone agent MDPV to pregnant mice can reduce birth rate and maternal care, and it also enhances motility (without impairment of motor coordination) of the offspring.

Suitability of a preserved human cadaver model for the simulation of facemask ventilation, direct laryngoscopy and tracheal intubation: a laboratory investigation.

BACKGROUND: Using fresh or formalin-embalmed cadavers has not been generally accepted for the purposes of teaching airway management. We investigated whether cadavers 'preserved according Thiel's embalming method' (PATEM) are suitable for the simulation of facemask ventilation and tracheal intubation by direct laryngoscopy. METHODS: This observational cluster sampling, controlled simulation study, included eight PATEM cadavers and eight manikins in two clusters. Twenty experienced anaesthetists were randomly assigned to execute 80 facemask ventilations and 80 tracheal intubations in both groups. The ease of facemask ventilation was the primary endpoint. The secondary endpoint was the composite outcomes of laryngoscopy and tracheal intubation. RESULTS: The success rate at the first attempt at mask ventilation was 74% (59/80 attempts) on cadavers and 41% (33/80 attempts) on manikins (P<0.0001). Twenty one subjects received an oral airway in both groups and succeeded in facemask ventilation 20 times on cadavers and four times on manikins (P=0.004). Two-handed technique mask ventilation was required 24 times on manikins and once on cadavers (P=0.0016). In one attempt on a manikin the mask ventilation was impossible. Poor laryngeal view (Cormack-Lehane grade 3) occurred 14 times among cadavers (17.5%) and once in manikins (1.25%) (P=0.007), whereas difficulties in tracheal intubation were encountered 16 times in cadavers (20%) vs 17 times in manikins (21.25%) (P=0.84). In a subjective evaluation the participants preferred the cadaver model over the manikins (P<0.0001). CONCLUSIONS: PATEM cadavers were better suited for facemask ventilation and provided a more realistic environment for laryngoscopy and tracheal intubation than the studied manikins.

Investigation of iron-containing products from natural and laboratory cultivated Sphaerotilus-Leptothrix bacteria.

Bacterial biomass collected from sheath-forming bacteria of the genera Sphaerotilus and Leptothrix was collected from a high-mountain natural stream water source. The elemental constitution and oxide phases of the products after selective cultivation of the bacteria on two different elective media using neutron activation analysis (NAA), electron microscopy (SEM, TEM), and X-ray diffraction (XRD) were studied. A high enrichment level of iron was revealed by the NAA technique in cultivated isolates as compared to the reference sample from nature. Three types of iron oxide compounds were established after cultivation in Adler's medium: lepidocrocite (γ-FeOOH), magnetite (Fe3O4), and goethite (α-FeOOH). The cultivation in the Isolation medium yielded a single phase, that of goethite, excluding one sample with a distinguishable amount of lepidocrocite. XRD and EM investigations show that the biogenic oxides are nanosized. Our study exemplifies the possibilities of the biotechnology approach for obtaining, under artificial conditions, large quantities of iron-containing by-products that could be of further used in appropriate nano- and biotechnologies.

Thermal conductivity of halide solid solutions: measurement and prediction.

The composition dependence of the lattice thermal conductivity in NaCl-KCl solid solutions has been measured as a function of composition and temperature. Samples with systematically varied compositions were prepared and the laser flash technique was used to determine the thermal diffusivity from 373 K to 823 K. A theoretical model, based on the Debye approximation of phonon density of state (which contains no adjustable parameters) was used to predict the thermal conductivity of both stoichiometric compounds and fully disordered solid solutions. The predictions obtained with the model agree very well with our measurement. A general method for predicting the thermal conductivity of different halide systems is discussed.

Assessment of cerebral tissue oxygen saturation in septic patients during acetazolamide provocation - a near infrared spectroscopy study.

UNLABELLED: Sepsis-associated encephalopathy is a multifactorially determined process of the brain parenchyma. Among other factors, vasogenic causes have been shown to play a role in its development. The aim of the present work was to assess whether cerebral tissue oxygen saturation is influenced by administration of acetazolamide in septic patients compared to controls. PATIENTS AND METHODS: 15 patients with severe sepsis and 10 healthy controls were studied. Cerebral oxygen saturation was assessed by INVOS 51 OOC Cerebral Oxymeter (NIRS) before and after administration of 15 mg/kg BW acetazolamide in both groups. RESULTS: The maximal rise that has been found in the partial pressure of CO(2) in the arterial blood of septic patients after administration of acetazolamide was from 35 ± 5 mmHg to 41.1 ± 6.3 mmHg. For the partial pressure of O(2) the observed increase was from 123.7 ± 47.1 mmHg to 139.9 ± 49 mmHg. Vasodilatory stimulus resulted in a similar maximal increase in cerebral oxygen saturation in septic patients and in controls (8.9 ± 6.5% for septic patients and 9.2 ± 4.6% for healthy persons, respectively). CONCLUSIONS: Cerebral vasoreactivity to acetazolamide is preserved in patients with severe sepsis.

Optimization of Friction Stir Welding Tool Advance Speed via Monte-Carlo Simulation of the Friction Stir Welding Process.

Recognition of the friction stir welding process is growing in the aeronautical and aero-space industries. To make the process more available to the structural fabrication industry (buildings and bridges), being able to model the process to determine the highest speed of advance possible that will not cause unwanted welding defects is desirable. A numerical solution to the transient two-dimensional heat diffusion equation for the friction stir welding process is presented. A non-linear heat generation term based on an arbitrary piecewise linear model of friction as a function of temperature is used. The solution is used to solve for the temperature distribution in the Al 6061-T6 work pieces. The finite difference solution of the non-linear problem is used to perform a Monte-Carlo simulation (MCS). A polynomial response surface (maximum welding temperature as a function of advancing and rotational speed) is constructed from the MCS results. The response surface is used to determine the optimum tool speed of advance and rotational speed. The exterior penalty method is used to find the highest speed of advance and the associated rotational speed of the tool for the FSW process considered. We show that good agreement with experimental optimization work is possible with this simplified model. Using our approach an optimal weld pitch of 0.52 mm/rev is obtained for 3.18 mm thick AA6061-T6 plate. Our method provides an estimate of the optimal welding parameters in less than 30 min of calculation time.

Full method validation for the determination of hexachlorobenzene and hexachlorobutadiene in fish tissue by GC-IDMS.

This paper summarizes the validation strategy and the results obtained for the simultaneous determination of hexachlorobenzene (HCB) and hexachlorobutadiene (HCBD) in fish tissue with a maximum of about 10% m/m fat content using a GC-IDMS technique. The method is applicable for the determination of HCB and HCBD at trace levels in different kinds of fish tissue samples in accordance with the requirements of the EU Directive 2008/105/EC establishing Environmental Quality Standard (EQS) levels for biota in aquatic ecosystems (10 ng/g for HCB and 55 ng/g for HCBD). The method validation aimed to assess performance parameters such as linearity, limit of detection/limit of quantification (LOD/LOQ), trueness, selectivity, intermediate precision, repeatability, stability of the extracts and robustness. The validation experiments have been performed by using uncontaminated fish tissue. Trueness was evaluated by using a certified reference material (NIST SRM 1947) (where applicable) and by the standard addition method. Very good linear signal-concentration curves were obtained for both analytes over the whole range of calibration. The repeatability and the intermediate precision of the method, expressed as relative standard deviation (RSD) and calculated at the EQS level, were estimated to be below 3% both for HCB and HCBD. The limits of quantification were 3.7 ng/g for HCB and 15.7 ng/g for HCBD in the fish. An uncertainty budget for the measurement of both HCB and HCBD in fish at about the EQS levels, applying the described method, has been established in the order of 10%. The analytical method and its performance characteristics take into account the requirements of EU Directive 2009/90/EC regarding the establishment of minimum performance criteria for the methods of analysis to be used in the water monitoring activity of the Water Framework Directive. Finally, the validated method was successfully tested on contaminated Silurus glanis from Ebro River (Spain). The method will be used in the homogeneity, stability and interlaboratory comparison studies for the characterization of a new candidate certified reference material.

One-lung ventilation does not result in cerebral desaturation during application of lung protective strategy if normocapnia is maintained.

BACKGROUND: Previously a report has suggested that administration of lung protective strategy for one-lung ventilation(OLV) results in oxygen desaturation of the brain parenchyma. The aim of our work was to confirm that the maintenance of normocapnia during protective OLV strategy results in alteration of cerebral blood fl ow and cerebral oxygen saturation as compared to double-lung ventilation. METHODS: Data were obtained from 24 patients undergoing thoracic surgery. Cerebral oxygen saturation (rSO2) was continuously monitored by INVOS 5100C Cerebral Oxymeter System along with measurement of cerebral blood fl ow velocity (MCAV) by transcranial Doppler sonography. Arterial blood samples were taken for blood gas analysis in the awake state, in the supine and lateral decubitus position during double-lung ventilation (DLV), and during OLV. RESULTS: When ventilation was changed from DLV to OLV, no significant change was observed in rSO2. A significant decrease of rSO2 was found compared to the value observed during DLV in lateral decubitus at the time point 60 minutes after the start of OLV. No clinically significant changes in the MCAV was observed throughout the course of the thoracic surgical procedure. CONCLUSIONS: OLV does not result in clinically relevant decreases in cerebral blood fl ow and cerebral oxygen saturation during application of lung protective ventilation if normocapnia is maintained.

Biomimetic oxidation of 3,5-di-tert-butylcatechol by dioxygen via Mn-enhanced base catalysis.

The 6-coordinate dioximatomanganese(II) complex [Mn(HL)(CH3OH)]+ (2, where H2L is [HON=C(CH3)C(CH3)=NCH2CH2]2NH), formed by instant solvolysis of [Mn2(HL)2](BPh4)2 (1) in methanol, accelerates the triethylamine (TEA)-catalyzed oxidation of 3,5-di-tert-butylcatechol (H2dtbc) by O2 to the corresponding o-benzoquinone. Significantly, 2 alone has no catalytic effect. The observed rate increase can be explained by the interaction of 2 with the hydroperoxo intermediate HdtbcO2- formed from Hdtbc- and O2 in the TEA-catalyzed oxidation. The kinetics of the TEA-catalyzed and Mn-enhanced reaction has been studied by gas-volumetric monitoring of the amount of O2 consumed. The initial rate of O2 uptake (V(in)) shows a first-order dependence on the concentration of 2 and O2 and saturation kinetics with respect to both H2dtbc and TEA. The observed kinetic behavior is consistent with parallel TEA-catalyzed and Mn-enhanced oxidation paths. The 3,5-di-tert-butylsemiquinone anion radical is an intermediate detectable by electron spin resonance (ESR) spectroscopy. The dimeric catalyst precursor has been characterized by X-ray diffraction and electrospray ionization mass spectrometry and the monomeric catalyst by ESR spectroscopy.

Hydrogen atom vs electron transfer in catecholase-mimetic oxidations by superoxometal complexes. Deuterium kinetic isotope effects.

Dioximato-cobalt(II), -iron(II) and -manganese(II) complexes (1)-(6), acting as functional catecholase and phenoxazinone synthase models, exhibit a deuterium kinetic isotope effect predicted by theory (k4H/k4D < or = 3) in the catalytic oxidative dehydrogenation of 3,5-di-tert-butylcatechol and 2-aminophenol by O2. KIEs in the range of (k4H/k4D approximately 1.79-3.51) are observed with (1) and (2) as catalysts, pointing to hydrogen atom transfer in the rate-determining step from the substrate hydroxy group to the metal-bound superoxo ligand. Less significant KIEs (1.06-1.20) are exhibited by catalysts systems (3)-(6), indicating that proton-coupled electron transfer is the preferred route in those cases.

Kinetics and mechanism of the ferroxime(II)-catalysed biomimetic oxidation of 2-aminophenol by dioxygen. A functional phenoxazinone synthase model.

[Fe(Hdmg)(2)(MeIm)(2)](1), referred to as ferroxime(II), is the precursor of a selective catalyst for the oxidative dehydrogenation of 2-aminophenol (Hap) to 2-amino-3H-phenoxazine-3-one (apx) by dioxygen under ambient conditions. The superoxoferroxime(III) species has been detected by ES-MS, and a 4-substituted 2-aminophenoxyl free radical by the ESR technique. The kinetics of the reaction was followed spectrophotometrically and by monitoring dioxygen uptake at constant pressure. According to the proposed mechanism, solvolysis of 1 is followed by O(2) binding to afford a superoxoferroxime, which abstracts an H-atom from Hap in the rate-determining step via an H-bonded intermediate, generating the free radical. This is supported by the observed primary deuterium kinetic isotope effect of 2.63. The system studied is a functional phenoxazinone synthase model.

Serum carotenoid and retinol levels during childhood infections.

BACKGROUND: In recent years, new physiological functions of vitamin A have been identified, including its role in immune defense. The antioxidant potential of carotenoids is thought to account for their health benefits. The aim of this study was to investigate the concentration changes in the provitamin-A (alpha- and-beta-carotene, beta-cryptoxanthin) and of the non-provitamin-A carotenoids (lutein, zeaxanthin and lycopene) in children with acute infections. METHODS: Serum retinol and carotenoid concentrations were measured by HPLC in 45 children suffering from acute infections and in 29 healthy controls. In addition 15 healthy children collected food samples over 2 days. C-reactive protein (CRP) levels were measured by turbidimetry. RESULTS: Serum levels of beta-carotene, alpha-carotene, beta-cryptoxanthin and retinol and non-provitamin-A carotenoid lutein and zeaxanthin concentrations were significantly lower in children with infections compared to healthy controls. There were significant negative correlations between CRP levels and serum beta-carotene and retinol concentrations. The average intake of retinol equivalents was 1.1 +/- 0.6 mg/day. CONCLUSION: Serum retinol and provitamin-A as well as non-provitamin-A carotenoid concentrations were lower in children with acute phase infections compared to healthy controls. The inverse correlations between CRP and beta-carotene or retinol indicate either decreased synthesis or increased utilization of these antioxidants.

Phosphoenolpyruvate carboxykinase in cucumber plants is increased both by ammonium and by acidification, and is present in the phloem.

In cucumber ( Cucumis sativus L.), phosphoenolpyruvate carboxykinase (PEPCK) was shown by activity measurements and immunoblots to be present in leaves, stems, roots, flowers, fruit and seed. However, immunolocalisation showed that it was present only in certain cell types. PEPCK was present in the companion cells of the adaxial phloem of minor veins, the adaxial and abaxial phloem of larger veins, the internal and external phloem of vascular bundles in petioles and stems, the phloem in roots and the extra-fascicular phloem in leaves, cotyledons, petioles and stems. Immunohistochemical evidence suggests that both the extra-fascicular phloem and the adaxial phloem are involved in the transport of amino acids. In roots and stems, the abundance of PEPCK was greatly increased by watering plants with a solution of ammonium chloride at low, but not at high pH. PEPCK also increased in leaves, but not roots or stems, of seedlings grown in an atmosphere containing 5% CO(2), and in roots and stems of seedlings watered with butyric acid. All these treatments are known to lower the pH of plant cells. Amino acid metabolism in the phloem may produce an excess of carbon skeletons, pH perturbations and an imbalance in the production/utilisation of NADH. This raises the possibility that PEPCK may function in the conversion of these carbon skeletons to PEP, which, depending on the energy requirements of the phloem, is subsequently utilised by either gluconeogenesis or the Krebs cycle, which both consume protons.

Protein assembly and heat stability in developing thylakoid membranes during greening.

The development of the thylakoid membrane was studied during illumination of dark-grown barley seedlings by using biochemical methods, and Fourier transform infrared and spin label electron paramagnetic resonance spectroscopic techniques. Correlated, gross changes in the secondary structure of membrane proteins, conformation, composition, and dynamics of lipid acyl chains, SDS/PAGE pattern, and thermally induced structural alterations show that greening is accompanied with the reorganization of membrane protein assemblies and the protein-lipid interface. Changes in overall membrane fluidity and noncovalent protein-lipid interactions are not monotonic, despite the monotonic accumulation of chlorophyll, LHCII [light-harvesting chlorophyll a/b-binding (polypeptides) associated with photosystem II] apoproteins, and 18:3 fatty acids that follow a similar time course with highest rates between 12-24 h of greening. The 18:3 fatty acid content increases 2.8-fold during greening. This appears to both compensate for lipid immobilization by membrane proteins and facilitate packing of larger protein assemblies. The increase in the amount of protein-solvating immobile lipids, which reaches a maximum at 12 h, is caused by 40% decrease in the membranous mean diameter of protein assemblies at constant protein/lipid mass ratio. Alterations in the SDS/PAGE pattern are most significant between 6-24 h. The size of membrane protein assemblies increases approximately 4.5-fold over the 12-48-h period, likely caused by the 2-fold gain in LHCII apoproteins. The thermal stability of thylakoid membrane proteins increases monotonically, as detected by an increasing temperature of partial protein unfolding during greening. Our data suggest that a structural coupling between major protein and lipid components develops during greening. This protein-lipid interaction is required for the development and protection of thylakoid membrane protein assemblies.

Plant tissue culture as a model for study of diversity in formaldehyde binding.

The effect of endogenous formaldehyde (HCHO) deprivation with dimedone - as abiotic stress - was investigated on the methylation-demethylation reactions in Datura innoxia Mill. callus cultures. The matrix assisted laser desorption/ionization mass spectrometric (MALDI MS) investigation of the culture extracts revealed characteristic differences between the tissues cultivated in light and dark. MALDI MS data show the presence of a precursor molecule and its mono- and tri-hydroxymethyl derivative, only in the cultures maintained in light. The relative amount of the different derivatives changed considerably, as a consequence of dimedone application in the culture medium and during the extraction.

Formaldehyde generators and capturers as influencing factors of mitotic and apoptotic processes.

There is a growing amount of evidence pointing to the fact that several endogenous and exogenous methylated compounds are potential formaldehyde generators in their biological reactions. N(G)-methylated lysines, N(G)-methylated as well as hydroxymethylated arginines, and 1'-methyl-ascorbigen have been examined in this respect. The apoptosis-inducing effect of formaldehyde molecules formed from methyl groups was earlier first published by our group. Dimedone, an artificial capturer molecule for formaldehyde, has been found to prevent the apoptosis-inducing effect of 1'-methyl-ascorbigen as well as N(G)-hydroxymethylated arginines. More recently resveratrol, present in grapes and wines, has been shown to have cardioprotective and cancer chemopreventive effect. Our group has been successful in demonstrating that this natural formaldehyde capturer molecule can also influence cell proliferation and apoptosis. The apoptosis-inducing or -preventing effect of formaldehyde generators and capturers seems to be dose-dependent and may be utilized in various disturbances of cell proliferation and active cell death.

Preliminary data on hard metal workers exposure to tungsten oxide fibres.

The first personal exposure data for tungsten oxide fibres, in two hard metal manufacturing industries is presented. Occupational exposure was studied by static and personal measurements during tungsten metal production. Three different initial materials were used, ammonium-paratungstate (APT), blue oxide and tungsten trioxide. In both factories, airborne tungsten oxide fibres were detected both in static and personal samples. Fibre exposure varies for different activities. Charging of raw material, changing the hammer, cleaning-work on the cyclone and the micro-filter were found to be among the most high dusty operations. However, as workers use respirators during cleaning operations, these filters could not be related to personal exposure. The calcination of APT to the blue oxide generates fibrous dust. The raw material imported as blue oxide is also fibrous material and both charging it into the calcination furnace and re-charging it into the reduction furnace generates unnecessarily additional dusty periods. A single reduction-stage is, therefore, preferable. Furthermore, the tungsten trioxide raw material is non-fibrous, therefore, calcination of APT to tungsten trioxide and its reduction to tungsten metal is preferable with respect to minimising workers exposure to tungsten oxide fibres.

Selenium and glutathione peroxidase activity in Hungarian children.

Selenium (Se) in plasma, whole blood and erythrocytes as well as glutathione peroxidase (GSH-Px) activity in plasma and erythrocytes were investigated in 161 healthy Hungarian children aged 1-15 years. Se was determined by AAS with hydride generation. The estimation of GSH-Px activity was performed in plasma with tertbutyl-hydroperoxide (t-BOOH) and in erythrocytes with hydrogen peroxide (H2O2) as acceptor substrates. The Se content in plasma (0.63 +/- 0.12 mumol/L), whole blood (0.81 +/- 0.14 mumol/L) and erythrocytes (1.14 +/- 0.26 mumol/L, the GSH-Px activity in plasma (87 +/- 19 U/L) and erythrocytes (5.93 +/- 1.04 U/gHb) was low in Hungarian children in comparison to values for children from other European countries. Samples from a rural area in southeast Hungary showed even lower Se content than samples from an industrial city in the northwest or from the capital. The Se in plasma and whole blood as well as GSH-Px activity in the plasma exhibited a clear age dependency. There was a good correlation between plasma Se and GSH-Px activity in all children (r = 0.633, p < 0.001). In addition, in children from the northwestern city and from the capital a correlation was found between Se content and GSH-Px activity of erythrocytes (r = 0.625, p < 0.001). There is no indication that the high mortality in young Hungarian adults from cardiovascular diseases is mainly caused by a low Se supply because there are no corresponding findings in the surrounding countries of southeastern or central eastern Europe with similar low Se states.