Metal recovery from spent lithium-ion batteries via two-step bioleaching using adapted chemolithotrophs from an acidic mine pit lake

The demand for lithium-ion batteries (LIBs) has dramatically increased in recent years due to their application in various electronic devices and electric vehicles (EVs). Great amount of LIB waste is generated, most of which ends up in landfills. LIB wastes contain substantial amounts of critical metals (such as Li, Co, Ni, Mn, and Cu) and can therefore serve as valuable secondary sources of these metals. Metal recovery from the black mass (shredded spent LIBs) can be achieved via bioleaching, a microbiology-based technology that is considered to be environmentally friendly, due to its lower costs and energy consumption compared to conventional pyrometallurgy or hydrometallurgy. However, the growth and metabolism of bioleaching microorganisms can be inhibited by dissolved metals. In this study, the indigenous acidophilic chemolithotrophs in a sediment from a highly acidic and metal-contaminated mine pit lake were enriched in a selective medium containing iron, sulfur, or both electron donors. The enriched culture with the highest growth and oxidation rate and the lowest microbial diversity (dominated by Acidithiobacillus and Alicyclobacillus spp. utilizing both electron donors) was then gradually adapted to increasing concentrations of Li+, Co2+, Ni2+, Mn2+, and Cu2+. Finally, up to 100% recovery rates of Li, Co, Ni, Mn, and Al were achieved via two-step bioleaching using the adapted culture, resulting in more effective metal extraction compared to bioleaching with a non-adapted culture and abiotic control.

Gene expression and metabolic activity of Streptococcus mutans during exposure to dietary carbohydrates glucose, sucrose, lactose, and xylitol

Recent RNA sequencing studies have given us a deeper insight into the cariogenic impact of carbohydrate sources in the bacterium Streptococcus mutans, the principal microbial agent in dental caries etiopathogenesis. The process of dental caries development is facilitated by the ability of this bacterium to ferment some carbohydrates into organic acids contributing to a pH decrease in the oral cavity and the demineralization of the hard tissues of the tooth. Furthermore, in dental caries progression, biofilm formation, which starts and ends with free planktonic cells, plays an important role and has several unique properties called virulence factors. The most cariogenic carbohydrate is sucrose, an easily metabolizable source of energy that induces the acidification and synthesis of glucans, forming typical bacterial cell clumps. We used multifaceted methodological approaches to compare the transcriptomic and metabolomic profiles of S. mutans growing in planktonic culture on preferred and nonpreferred carbohydrates and in fasting conditions. Streptococcus mutans in a planktonic culture with lactose produced the same pH drop as glucose and sucrose. By contrast, xylitol and lactose showed high effectiveness in regulating intracellular polysaccharide metabolism, cell wall structure, and overall virulence involved in the initial phase of biofilm formation and structure but with an opposite pattern compared with sucrose and glucose. Our results confirmed the recent findings that xylitol and lactose play a vital role in biofilm structure. However, they do not reduce its formation, which is related to the creation of a cariogenic environment.

Zinc recovery from bioleachate using a microbial electrolysis cell and comparison with selective precipitation

Metal recycling is essential for strengthening a circular economy. Microbial leaching (bioleaching) is an economical and environmentally friendly technology widely used to extract metals from insoluble ores or secondary resources such as dust, ashes, and slags. On the other hand, microbial electrolysis cells (MECs) would offer an energy-efficient application for recovering valuable metals from an aqueous solution. In this study, we investigated a MEC for Zn recovery from metal-laden bioleachate for the first time by applying a constant potential of -100 mV vs. Ag/AgCl (3 M NaCl) on a synthetic wastewater-treating bioanode. Zn was deposited onto the cathode surface with a recovery efficiency of 41 ± 13% and an energy consumption of 2.55 kWh kg-1. For comparison, Zn recovery from zinc sulfate solution resulted in a Zn recovery efficiency of 100 ± 0% and an energy consumption of 0.70 kWh kg-1. Furthermore, selective metal precipitation of the bioleachate was performed. Individual metals were almost completely precipitated from the bioleachate at pH 5 (Al), pH 7 (Zn and Fe), and pH 9 (Mg and Mn).

Influence of mobile genetic elements and insertion sequences in long- and short-term adaptive processes of Acidithiobacillus ferrooxidans strains

The recent revision of the Acidithiobacillia class using genomic taxonomy methods has shown that, in addition to the existence of previously unrecognized genera and species, some species of the class harbor levels of divergence that are congruent with ongoing differentiation processes. In this study, we have performed a subspecies-level analysis of sequenced strains of Acidithiobacillus ferrooxidans to prove the existence of distinct sublineages and identify the discriminant genomic/genetic characteristics linked to these sublineages, and to shed light on the processes driving such differentiation. Differences in the genomic relatedness metrics, levels of synteny, gene content, and both integrated and episomal mobile genetic elements (MGE) repertoires support the existence of two subspecies-level taxa within A. ferrooxidans. While sublineage 2A harbors a small plasmid related to pTF5, this episomal MGE is absent in sublineage 2B strains. Likewise, clear differences in the occurrence, coverage and conservation of integrated MGEs are apparent between sublineages. Differential MGE-associated gene cargo pertained to the functional categories of energy metabolism, ion transport, cell surface modification, and defense mechanisms. Inferred functional differences have the potential to impact long-term adaptive processes and may underpin the basis of the subspecies-level differentiation uncovered within A. ferrooxidans. Genome resequencing of iron- and sulfur-adapted cultures of a selected 2A sublineage strain (CCM 4253) showed that both episomal and large integrated MGEs are conserved over twenty generations in either growth condition. In turn, active insertion sequences profoundly impact short-term adaptive processes. The ISAfe1 element was found to be highly active in sublineage 2A strain CCM 4253. Phenotypic mutations caused by the transposition of ISAfe1 into the pstC2 encoding phosphate-transport system permease protein were detected in sulfur-adapted cultures and shown to impair growth on ferrous iron upon the switch of electron donor. The phenotypic manifestation of the △pstC2 mutation, such as a loss of the ability to oxidize ferrous iron, is likely related to the inability of the mutant to secure the phosphorous availability for electron transport-linked phosphorylation coupled to iron oxidation. Depletion of the transpositional △pstC2 mutation occurred concomitantly with a shortening of the iron-oxidation lag phase at later transfers on a ferrous iron-containing medium. Therefore, the pstII operon appears to play an essential role in A. ferrooxidans when cells oxidize ferrous iron. Results highlight the influence of insertion sequences and both integrated and episomal mobile genetic elements in the short- and long-term adaptive processes of A. ferrooxidans strains under changing growth conditions.

Bioelectrochemical methanation by utilization of steel mill off-gas in a two-chamber microbial electrolysis cell

Carbon capture and utilization has been proposed as one strategy to combat global warming. Microbial electrolysis cells (MECs) combine the biological conversion of carbon dioxide (CO₂) with the formation of valuable products such as methane. This study was motivated by the surprising gap in current knowledge about the utilization of real exhaust gas as a CO₂ source for methane production in a fully biocatalyzed MEC. Therefore, two steel mill off-gases differing in composition were tested in a two-chamber MEC, consisting of an organic substrate-oxidizing bioanode and a methane-producing biocathode, by applying a constant anode potential. The methane production rate in the MEC decreased immediately when steel mill off-gas was tested, which likely inhibited anaerobic methanogens in the presence of oxygen. However, methanogenesis was still ongoing even though at lower methane production rates than with pure CO₂. Subsequently, pure CO₂ was studied for methanation, and the cathodic biofilm successfully recovered from inhibition reaching a methane production rate of 10.8 L m⁻²d⁻¹. Metagenomic analysis revealed Geobacter as the dominant genus forming the anodic organic substrate-oxidizing biofilms, whereas Methanobacterium was most abundant at the cathodic methane-producing biofilms.

Optimized biogenic sulfuric acid production and application in the treatment of waste incineration residues

The biological leaching of metals from different waste streams by bacteria is intensively investigated to address metal recycling and circular economy goals. However, usually external addition of sulfuric acid is required to maintain the low pH optimum of the bacteria to ensure efficient leaching. Extremely acidophilic Acidithiobacillus spp. producing sulfuric acid and ferric iron have been investigated for several decades in the bioleaching of metal-containing ores. Their application has now been extended to the extraction of metals from artificial ores and other secondary sources. In this study, an optimized process for producing biogenic sulfuric acid from elemental sulfur by two sulfur-oxidizing species, A. thiooxidans and A. caldus and their combinations, was investigated in batch and stirred tank experiments. Using a combined culture of both species, 1.05 M and 1.4 M biogenic sulfuric acid was produced at 30 °C and 6% elemental sulfur in batch and semi continuous modes, respectively. The acid produced was then used to control the pH in a heap bioleaching system in which iron- and sulfur-oxidizing A. ferrooxidans was applied to biologically leach metals from waste incineration residuals. Metals like Cu, Ni, Al, Mn, and Zn were successfully recovered by 99, 93, 84, 77 and 68%, respectively within three weeks of heap bioleaching. Overall, a potential value recovery of incorporated metals >70% could be achieved. This highlights the potential and novelty of applying extremely acidophilic sulfur-oxidizing bacteria for cheap and efficient production of biogenic sulfuric acid and its use in pH control.

Linear Atomic Cluster Expansion Force Fields for Organic Molecules: Beyond RMSE

We demonstrate that fast and accurate linear force fields can be built for molecules using the atomic cluster expansion (ACE) framework. The ACE models parametrize the potential energy surface in terms of body-ordered symmetric polynomials making the functional form reminiscent of traditional molecular mechanics force fields. We show that the four- or five-body ACE force fields improve on the accuracy of the empirical force fields by up to a factor of 10, reaching the accuracy typical of recently proposed machine-learning-based approaches. We not only show state of the art accuracy and speed on the widely used MD17 and ISO17 benchmark data sets, but we also go beyond RMSE by comparing a number of ML and empirical force fields to ACE on more important tasks such as normal-mode prediction, high-temperature molecular dynamics, dihedral torsional profile prediction, and even bond breaking. We also demonstrate the smoothness, transferability, and extrapolation capabilities of ACE on a new challenging benchmark data set comprised of a potential energy surface of a flexible druglike molecule.

Impact of Carbon Felt Electrode Pretreatment on Anodic Biofilm Composition in Microbial Electrolysis Cells

Sustainable technologies for energy production and storage are currently in great demand. Bioelectrochemical systems (BESs) offer promising solutions for both. Several attempts have been made to improve carbon felt electrode characteristics with various pretreatments in order to enhance performance. This study was motivated by gaps in current knowledge of the impact of pretreatments on the enrichment and microbial composition of bioelectrochemical systems. Therefore, electrodes were treated with poly(neutral red), chitosan, or isopropanol in a first step and then fixed in microbial electrolysis cells (MECs). Four MECs consisting of organic substance-degrading bioanodes and methane-producing biocathodes were set up and operated in batch mode by controlling the bioanode at 400 mV vs. Ag/AgCl (3M NaCl). After 1 month of operation, Enterococcus species were dominant microorganisms attached to all bioanodes and independent of electrode pretreatment. However, electrode pretreatments led to a decrease in microbial diversity and the enrichment of specific electroactive genera, according to the type of modification used. The MEC containing isopropanol-treated electrodes achieved the highest performance due to presence of both Enterococcus and Geobacter. The obtained results might help to select suitable electrode pretreatments and support growth conditions for desired electroactive microorganisms, whereby performance of BESs and related applications, such as BES-based biosensors, could be enhanced.

Leachability of metals from waste incineration residues by iron- and sulfur-oxidizing bacteria

Hazardous waste disposal via incineration generates a substantial amount of ashes and slags which pose an environmental risk due to their toxicity. Currently, these residues are deposited in landfills with loss of potentially recyclable raw material. In this study, the use of acidophilic bioleaching bacteria (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferrooxidans) as an environmentally friendly, efficient strategy for the recovery of valuable metals from incineration residues was investigated. Zinc, Cobalt, Copper, and Manganese from three different incineration residues were bio-extracted up to 100% using A. ferrooxidans under ferrous iron oxidation. The other metals showed lower leaching efficiencies based on the type of culture used. Sulfur-oxidizing cultures A. ferrooxidans and A. thiooxidans, containing sulfur as the sole substrate, expressed a significantly lower leaching efficiency (up to 50%). According to ICP-MS, ashes and slags contained Fe, Zn, Cu, Mn, Cr, Cd, and Ni in economically attractive concentrations between 0.2 and 75 mg g^-1. Compared to conventional hydrometallurgical and pyrometallurgical processes, our biological approach provides many advantages such as: the use of a limited amount of used strong acids (H₂SO₄ or HCl), recycling operations at lower temperatures (~30 °C) and no emission of toxic gases during combustion (i.e., dioxins and furans).

A Model of Aerobic and Anaerobic Metabolism of Hydrogen in the Extremophile Acidithiobacillus ferrooxidans

Hydrogen can serve as an electron donor for chemolithotrophic acidophiles, especially in the deep terrestrial subsurface and geothermal ecosystems. Nevertheless, the current knowledge of hydrogen utilization by mesophilic acidophiles is minimal. A multi-omics analysis was applied on Acidithiobacillus ferrooxidans growing on hydrogen, and a respiratory model was proposed. In the model, [NiFe] hydrogenases oxidize hydrogen to two protons and two electrons. The electrons are used to reduce membrane-soluble ubiquinone to ubiquinol. Genetically associated iron-sulfur proteins mediate electron relay from the hydrogenases to the ubiquinone pool. Under aerobic conditions, reduced ubiquinol transfers electrons to either cytochrome aa ₃ oxidase via cytochrome bc ₁ complex and cytochrome c ₄ or the alternate directly to cytochrome bd oxidase, resulting in proton efflux and reduction of oxygen. Under anaerobic conditions, reduced ubiquinol transfers electrons to outer membrane cytochrome c (ferrireductase) via cytochrome bc ₁ complex and a cascade of electron transporters (cytochrome c ₄, cytochrome c ₅₅₂, rusticyanin, and high potential iron-sulfur protein), resulting in proton efflux and reduction of ferric iron. The proton gradient generated by hydrogen oxidation maintains the membrane potential and allows the generation of ATP and NADH. These results further clarify the role of extremophiles in biogeochemical processes and their impact on the composition of the deep terrestrial subsurface.

Metabolic cardio- and reno-protective effects of empagliflozin in a prediabetic rat model

The mechanisms behind the cardiovascular and renal benefits of empagliflozin is not fully understood. The positive impact of the medication on cardiovascular mortality can not be solely attributed to its antidiabetic effect, with a metabolic mechanism possibly involved. To investigate the metabolic effects of empagliflozin treatment (10 mg/kg/day for 6 weeks), we used an adult male rat model with serious vascular complications associated with metabolic syndrome and prediabetes. Impaired glucose tolerance, severe albuminuria and impaired insulin sensitivity were induced by intragastric administration of methylglyoxal and high sucrose diet feeding for four months. Although empagliflozin decreased body weight, non-fasting glucose and insulin, glucagon levels remained unchanged. In addition, empagliflozin increased adiponectin levels (+40%; p < 0.01) and improved skeletal muscle insulin sensitivity. Increased non-esterified fatty acids (NEFA) in empagliflozin-treated rats is understood to generate ketone bodies. Empagliflozin increased β-hydroxybutyrate levels in serum (+66%; p < 0.05) and the myocardium (30%; p < 0.01), suggesting its possible involvement as an alternative substrate for metabolism. Empagliflozin switched substrate utilisation in the myocardium, diverting glucose oxidation to fatty acid oxidation. Representing another favorable effect, empagliflozin also contributed to decreased uric acid plasma levels (-19%; p < 0.05). In the kidney cortex, empagliflozin improved oxidative and dicarbonyl stress parameters and increased gene expression of β-hydroxybutyrate dehydrogenase, an enzyme involved in ketone body utilisation. In addition, empagliflozin decreased microalbuminuria (-27%; p < 0.01) and urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion (-29%; p < 0.01). Our results reveal the important systemic metabolic effect of empagliflozin on alterations in substrate utilisation and on increased ketone body use in prediabetic rats. Improved oxidative and dicarbonyl stress and decreased uric acid are also possibly involved in the cardio- and reno-protective effects of empagliflozin.

FliI6-FliJ molecular motor assists with unfolding in the type III secretion export apparatus

The role of rotational molecular motors of the ATP synthase class is integral to the metabolism of cells. Yet the function of FliI6-FliJ complex, a homolog of the F1 ATPase motor, within the flagellar export apparatus remains unclear. We use a simple two-state model adapted from studies of linear molecular motors to identify key features of this motor. The two states are the 'locked' ground state where the FliJ coiled coil filament experiences angular fluctuations in an asymmetric torsional potential, and a 'free' excited state in which FliJ undergoes rotational diffusion. Michaelis-Menten kinetics was used to treat transitions between these two states, and obtain the average angular velocity of the unloaded FliJ filament within the FliI6 stator: ωmax ≈ 9.0 rps. The motor was then studied under external counter torque conditions in order to ascertain its maximal power output: Pmax ≈ 42 kBT/s (or 102 kW/mol), and the stall torque: Gstall ≈ 3 kBT/rad (or 0.01 nN·nm/rad). Two modes of action within the flagellar export apparatus are proposed, in which the motor performs useful work either by continuously 'grinding' through the resistive environment of the export gate, or by exerting equal and opposite stall force on it. In both cases, the resistance is provided by flagellin subunits entering the flagellar export channel prior to their unfolding. We therefore propose that the function of the FliI6-FliJ complex is to lower the energy barrier, and therefore assist in unfolding of the flagellar proteins before feeding them into the transport channel.

Can Sulfate Be the First Dominant Aqueous Sulfur Species Formed in the Oxidation of Pyrite by Acidithiobacillus ferrooxidans?

According to the literature, pyrite (FeS₂) oxidation has been previously determined to involve thiosulfate as the first aqueous intermediate sulfur product, which is further oxidized to sulfate. In the present study, pyrite oxidation by Acidithiobacillus ferrooxidans was studied using electrochemical and metabolic approaches in an effort to extend existing knowledge on the oxidation mechanism. Due to the small surface area, the reaction rate of a compact pyrite electrode in the form of polycrystalline pyrite aggregate in A. ferrooxidans suspension was very slow at a spontaneously formed high redox potential. The slow rate made it possible to investigate the oxidation process in detail over a term of 100 days. Using electrochemical parameters from polarization curves and levels of released iron, the number of exchanged electrons per pyrite molecule was estimated. The values close to 14 and 2 electrons were determined for the oxidation with and without bacteria, respectively. These results indicated that sulfate was the dominant first aqueous sulfur species formed in the presence of bacteria and elemental sulfur was predominantly formed without bacteria. The stoichiometric calculations are consistent with high iron-oxidizing activities of bacteria that continually keep the released iron in the ferric form, resulting in a high redox potential. The sulfur entity of pyrite was oxidized to sulfate by Fe³⁺ without intermediate thiosulfate under these conditions. Cell attachment on the corroded pyrite electrode surface was documented although pyrite surface corrosion by Fe³⁺ was evident without bacterial participation. Attached cells may be important in initiating the oxidation of the pyrite surface to release iron from the mineral. During the active phase of oxidation of a pyrite concentrate sample, the ATP levels in attached and planktonic bacteria were consistent with previously established ATP content of iron-oxidizing cells. No significant upregulation of three essential genes involved in energy metabolism of sulfur compounds was observed in the planktonic cells, which represented the dominant biomass in the pyrite culture. The study demonstrated the formation of sulfate as the first dissolved sulfur species with iron-oxidizing bacteria under high redox potential conditions. Minor aqueous sulfur intermediates may be formed but as a result of side reactions.

Stoichiometry of bacterial anaerobic oxidation of elemental sulfur by ferric iron

The conventional stoichiometry of the oxidation of elemental sulfur by ferric iron in Acidithiobacillus ferrooxidans was not in agreement with our experimental data in terms of ferrous iron and proton formation. Reaction modelling under the actual conditions of bacterial activity resulted in a different stoichiometry, where additional iron species participate in the process to affect the number of released protons. The suggested reaction equation may more accurately predict the intensity of environmental acidification during the anaerobic bioprocess.

Kinetics of anaerobic elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans and protein identification by comparative 2-DE-MS/MS

Elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans was investigated. The apparent Michaelis constant for ferric iron was 18.6 mM. An absence of anaerobic ferric iron reduction ability was observed in bacteria maintained on elemental sulfur for an extended period of time. Upon transition from ferrous iron to elemental sulfur medium, the cells exhibited similar kinetic characteristics of ferric iron reduction under anaerobic conditions to those of cells that were originally maintained on ferrous iron. Nevertheless, a total loss of anaerobic ferric iron reduction ability after the sixth passage in elemental sulfur medium was demonstrated. The first proteomic screening of total cell lysates of anaerobically incubated bacteria resulted in the detection of 1599 protein spots in the master two-dimensional electrophoresis gel. A set of 59 more abundant and 49 less abundant protein spots that changed their protein abundances in an anaerobiosis-dependent manner was identified and compared to iron- and sulfur-grown cells, respectively. Proteomic analysis detected a significant increase in abundance under anoxic conditions of electron transporters, such as rusticyanin and cytochrome c(552), involved in the ferrous iron oxidation pathway. Therefore we suggest the incorporation of rus-operon encoded proteins in the anaerobic respiration pathway. Two sulfur metabolism proteins were identified, pyridine nucleotide-disulfide oxidoreductase and sulfide-quinone reductase. The important transcription regulator, ferric uptake regulation protein, was anaerobically more abundant. The anaerobic expression of several proteins involved in cell envelope formation indicated a gradual adaptation to elemental sulfur oxidation.

Intraspecific variation in Viola suavis in Europe: parallel evolution of white-flowered morphotypes

BACKGROUND AND AIMS

Viola species are commonly grown for their ornamental flowers, but their evolutionary history and taxonomy are often complicated and have been poorly explored so far. This is a study of the polymorphic, typically blue-flowered species Viola suavis, concentrating on the white-flowered populations of uncertain taxonomic assignment that occur in Spain and central and south-eastern Europe. The aim was to resolve their origin and taxonomic status and to study the intraspecific structure and (post)glacial history of this species.

METHODS

Viola suavis and five close relatives were sampled from multiple locations and subjected to molecular (AFLP, sequencing of nrDNA ITS) and morphometric analyses. Data on ploidy level and pollen fertility were also obtained, to address an assumed hybrid origin of the white-flowered populations.

KEY RESULTS

In V. suavis a strong intraspecific genetic split into two groups was observed, indicating that there has been a long-term isolation and survival in distinct glacial refugia. The white-flowered populations could be placed within the variation range of this species, and it is clear that they evolved independently in two distant areas. Their parallel evolution is supported by both morphological and genetic differentiation. The strongly reduced genetic variation and absence of unique AFLP fragments suggest their derived status and origin from the typical, blue-flowered populations.

CONCLUSIONS

These results suggest that intraspecific variation in V. suavis has been largely shaped by population isolations during the last glaciation and subsequent recolonizations, although cultivation and vegetative spread by humans have affected the present picture as well.

Field vaccination of broilers against coccidiosis

Control of coccidiosis by vaccination or by medication with anti-coccidial drugs were compared on a commercial broiler farm. An attenuated, embryo-adapted line of Eimeria tenella, a virulent laboratory strain of E. acervulina and a precocious (attenuated) line of E. maxima, used for vaccination, were given in three combinations: E. tenella alone, E. tenella plus E. acervulina or E. tenella together with E. acervulina and E. maxima. Oocysts were given via feed when chickens were 2 to 8 days old. In four trials the performance of 8,416 chickens vaccinated with E. tenella alone or in combination with E. acervulina was as that of chickens given anticoccidial drugs. The performance of 3,601 chickens vaccinated with E. tenella, E. acervulina and E. maxima was not better than that of chickens vaccinated with E. tenella and E. acervulina only. The performance of 61,772 chickens vaccinated with E. tenella and E. acervulina in four large scale crops was similar to that of the control chickens and that of the previous six crops, which had been medicated with anticoccidial drugs.

Monoquaternary pyridinium salts with modified side chain-synthesis and evaluation on model of tabun- and paraoxon-inhibited acetylcholinesterase

Acetylcholinesterase reactivators are crucial antidotes for the treatment of organophosphate intoxication. Eighteen monoquaternary reactivators of acetylcholinesterase with modified side chain were developed in an effort to extend the properties of pralidoxime. The known reactivators (pralidoxime, HI-6, obidoxime, trimedoxime, methoxime) and the prepared compounds were tested in vitro on a model of tabun- and paraoxon-inhibited AChE. Monoquaternary reactivators were not able to exceed the best known compounds for tabun poisoning, but some of them did show reactivation better or comparable with pralidoxime for paraoxon poisoning. However, extensive differences were found by a SAR study for various side chains on the non-oxime part of the reactivator molecule.

Mutilating electrotrauma--case report

The passage of electric current through a human body causes polarization changes in cell membranes, which can possibly lead to the death of these cells. At the same time, electric energy is transformed to thermal energy, primarily in high resistance tissues. We present a case report of a 22-year-old male who was hit by an electric current with a voltage of 22 kV when he was working on a high-voltage overhead line tower. Primary treatment which included fasciotomies was completed two hours after the injury. Fasciotomies and revisions of all muscle groups were completed on the left upper extremity and right shank. On the right upper extremity fasciotomies were completed on the forearm. Retinaculum flexorum was cut in the area of both wrists. Despite the complex therapy including higher doses of a low-molecular-weight heparin, ischemization of the whole left upper extremity and distal part of right shank and foot occurred. On the sixth day after the injury it was necessary to amputate the right lower extremity in shank and on the eighth day after injury to amputate the left upper extremity below the shoulder, and on the fourteenth day, due to progressive ischemic necrosis, it was necessary to complete exarticulation of the left shoulder. The 45th day after the injury our team of micro-surgeons closed the defect of soft tissues in the distal part of right forearm and radial part of right hand by transferred parascapular fasciocutaneous flap. The right median nerve appeared to be necrotic in the distal part of forearm even at the day of injury. Four months after the injury the 12 cm long defect of the right median nerve was bypassed by a graft from the suralis nerve. Outpatient care followed as well as physical and psychological rehabilitation. The support of the family was admirable. One and a half years after the injury reconstruction of the right thumb flexor tendon was completed. Two years after the injury function of the right hand in terms of grip function was satisfactory (patient was able to complete pinch grip and sign). Gait with the prosthesis was very good.

Differential sensitivity of skeletal and fusimotor neurons to Bcl-2-mediated apoptosis during neuromuscular development

Proper development of the nervous system requires that a carefully controlled balance be maintained between both proliferation and neuronal survival. The process of programmed cell death is believed to play a key role in regulating levels of neuronal survival, in large part through the action of antiapoptotic proteins, such as Bcl-2. Consistent with this, Bcl-2 has been shown to be a key regulator of apoptotic signaling in post-mitotic neurons. However, we still know remarkably little regarding the role that Bcl-2 plays in regulating the survival of specific motor neuron populations. In the present study, we have examined somatic motor neurons of the lumbar spinal cord, and branchiomotor neurons of the facial nucleus in bcl-2-null mice to determine the differential dependence among motor neuron populations with respect to Bcl-2-mediated survival. Examination of neuronal and axon number, axonal area, and the distribution of axonal loss in bcl-2-null mice demonstrates that, in contrast to the great majority of alpha motor neurons, gamma motor neurons exhibit a unique dependence upon bcl-2 for survival. These results demonstrate, for the first time, the connection between Bcl-2 expression, motor neuron survival, and the establishment of different motor populations.

[Approximative intestinal anastomosis in newborns with multifocal necrotizing enterocolitis]

Multifocal necrotizing enterocolitis (NEC) may result in extensive bowel necrosis and short bowel syndrome. Authors present case report of premature newborn (BW 1700 g, gestational age 30 w.) where an extensive multisegmental NEC of small and large intestine was found during first explorative laparotomy. Proximal jejunostomy 28 cm beyond ligament of Treitz was performed and the rest of involved intestine was left in situ. After 48 hours multiple small bowel resections were performed leaving 12 cm of small intestine (5 short segments) distal to the jejunostomy. Five approximative anastomoses were performed to restore continuity among these segments and ileocaecal valve. Each of approximative anastomosis was constructed with limited number of 4-6 interrupted stitches and all anastomoses healed without complication. Intestinal continuity between proximal jejunostomy and the reconstructed segment of ileum was reestablished nine weeks later. Total length of small bowel was 50 cm. The patient was discharged at the age of 5 months weighing 4145 g with supplemental pareneteral nutrition. The technique of rapid approximative anastomosis may contribute to save maximal intestinal length in cases with the risk of short bowel syndrome.

Hybridization between two polyploid Cardamine (Brassicaceae) species in North-western Spain: discordance between morphological and genetic variation patterns

BACKGROUND AND AIMS

Hybridization is an important evolutionary phenomenon, and therefore a detailed understanding of the dynamics of interspecific gene flow and resulting morphological and genetic patterns is of widespread interest. Here hybridization between the polyploids Cardamine pratensis and C. raphanifolia at four localities is explored. Using different types of data, the aim is to provide simultaneous and direct comparisons between genotype and phenotype variation patterns in the studied hybrid populations.

METHODS

Evidence of hybridization has been gathered from morphology, molecular markers (amplified fragment length polymorphism and chloroplast DNA sequences), pollen viability, karyology and nuclear DNA content.

KEY RESULTS

All data support extensive gene flow occurring in the hybrid populations. A wide range of morphological and genetic variation is observed, which includes both parental and intermediate types. Unbalanced pollen fertility and several ploidy levels are recorded.

CONCLUSIONS

Incongruence reported between genotype and phenotype suggests that parental phenotypes are affected by introgression, and intermediate hybrid phenotypes can be genetically closer to one of the parents. Thus, it is evident that morphology, when used alone, can be misleading for interpreting hybridization, and critical evaluation of other data is needed.

Tree water storage and its diurnal dynamics related to sap flow and changes in stem volume in old-growth Douglas-fir trees

Diurnal and seasonal tree water storage was studied in three large Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees at the Wind River Canopy Crane Research site. Changes in water storage were based on measurements of sap flow and changes in stem volume and tissue water content at different heights in the stem and branches. We measured sap flow by two variants of the heat balance method (with internal heating in stems and external heating in branches), stem volume with electronic dendrometers, and tissue water content gravimetrically. Water storage was calculated from the differences in diurnal courses of sap flow at different heights and their integration. Old-growth Douglas-fir trees contained large amounts of free water: stem sapwood was the most important storage site, followed by stem phloem, branch sapwood, branch phloem and needles. There were significant time shifts (minutes to hours) between sap flow measured at different positions within the transport system (i.e., stem base to shoot tip), suggesting a highly elastic transport system. On selected fine days between late July and early October, when daily transpiration ranged from 150 to 300 liters, the quantity of stored water used daily ranged from 25 to 55 liters, i.e., about 20% of daily total sap flow. The greatest amount of this stored water came from the lower stem; however, proportionally more water was removed from the upper parts of the tree relative to their water storage capacity. In addition to lags in sap flow from one point in the hydrolic pathway to another, the withdrawal and replacement of stored water was reflected in changes in stem volume. When point-to-point lags in sap flow (minutes to hours near the top and stem base, respectively) were considered, there was a strong linear relationship between stem volume changes and transpiration. Volume changes of the whole tree were small (equivalent to 14% of the total daily use of stored water) indicating that most stored water came from the stem and from its inelastic (sapwood) tissues. Whole tree transpiration can be maintained with stored water for about a week, but it can be maintained with stored water from the upper crown alone for no more than a few hours.

Neurotrophin-3 ameliorates sensory-motor deficits in Er81-deficient mice

Two factors, the ETS transcription factor ER81 and skeletal muscle-derived neurotrophin-3 (NT3), are essential for the formation of muscle spindles and the function of spindle afferent-motoneuron synapses in the spinal cord. Spindles either degenerate completely or are abnormal, and spindle afferents fail to project to spinal motoneurons in Er81 null mice; however, the interactions between ER81 and NT3 during the processes of afferent neuron and muscle spindle development are poorly understood. To examine if overexpression of NT3 in muscle rescues spindles and afferent-motoneuron connectivity in the absence of ER81, we generated myoNT3;Er81(-/-) double-mutant mice that selectively overexpress NT3 in muscle in the absence of ER81. Spindle reflex arcs in myoNT3;Er81(-/-) mutants differed greatly from Er81 null mice. Muscle spindle densities were greater and more afferents projected into the ventral spinal cord in myoNT3;Er81(-/-) mice. Spindles of myoNT3;Er81(-/-) muscles responded normally to repetitive muscle taps, and the monosynaptic inputs from Ia afferents to motoneurons, grossly reduced in Er81(-/-) mutants, were restored to wild-type levels in myoNT3;Er81(-/-) mice. Thus, an excess of muscle-derived NT3 reverses deficits in spindle numbers and afferent function induced by the absence of ER81. We conclude that muscle-derived NT3 can modulate spindle density and afferent-motoneuron connectivity independently of ER81.

Experience in non-conventional wastewater treatment techniques used in the Czech Republic

Among the most common non-conventional wastewater treatment techniques used in the Czech Republic are waste stabilisation ponds (WSP), subsurface horizontal flow constructed wetlands (CW) and vertical flow groundfilters (GF). These extensive systems can be advantageously used for treatment of waters coming from sewerages where the ballast weighting commonly makes more than half of dry-weather flow. The monitoring was focused at 14 different extensive systems. Organics removal efficiencies were favourable (CW-82%; GF-88%); in the case of WSP only 57% due to the algal bloom. Total nitrogen removal efficiencies were 43 and 47% for WSP and GF; in the case of CW only 32% due to often occurring anaerobic conditions in filter beds. Total phosphorus removal efficiencies were 37, 35 and 22% for WSP, GF and CW, respectively. Often occurring problems are the ice-blockage of surface aerators at WSP during wintertimes, the pond duckweed-cover or the algal bloom at WSP during summers; a gradual colmatage of filter systems; and the oxygen deficiency in beds of subsurface horizontal flow constructed wetlands. Czech legal regulations do not allow treated wastewater disposal into underground waters. There is only an exception for individual family houses. Up to now, knowledge gained by monitoring of a village (which uses the infiltration upon a permission issued according to earlier legal regulations) have not shown an unacceptable groundwater quality deterioration into the infiltration areas.

Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol)

A reference material for the biological monitoring of occupational exposure to toluene, benzene and phenol was prepared. O-cresol and hippuric acid (metabolites of toluene) are used for the biological monitoring of occupational exposure to toluene. Phenol, a metabolite of benzene, is used for the biological monitoring of exposure to benzene, but phenol can of course also be used as an indicator of exposure to phenol as well. The reference material (RM) used for the determination of these metabolites was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to toluene and those taking part in an inhalation experiment. Tests for homogeneity and stability were performed by determining urine concentrations of o-cresol, hippuric acid, creatinine and phenol. To investigate the stability of the RM, the urinary concentrations of o-cresol and phenol were monitored for eighteen months using GC and HPLC, while those of hippuric acid and creatinine were followed for five and six years, respectively, using HPLC. Analysis of variance showed that the concentrations did not change. The certified concentration values (and their uncertainties) of the substances in this reference material (phenol concentration c=6.46+/-0.58 mg l(-1); o-cresol concentration c=1.17+/-0.15 mg l(-1); hippuric acid concentration c=1328+/-30 mg l(-1); creatinine concentration c=0.82+/-0.10 g l(-1)) were evaluated via the interactive statistical programme IPECA.

ETS transcription factor ER81 is required for the pacinian corpuscle development

ER81, a member of the ETS family of transcription factors, is involved in processes of specification of neuronal identity, control of sensory-motor connectivity, and differentiation of muscle spindles. Spindles either degenerate or are abnormal in mutant mice lacking ER81. We examined whether ER81 is required for the development of another class of mechanoreceptors, the Pacinian corpuscle. ER81 was expressed by the inner core cells of the corpuscles, as reflected by expression of the lacZ reporter gene in Er81(+/lacZ) mutants, thereby suggesting a role for ER81 in the corpuscle development. No Pacinian corpuscles or their afferent nerve fibers were present in the crus of Er81 null mice at birth. Legs of mutant embryos examined at E16.5 were also devoid of the corpuscles, but not of their afferents. Thus, Pacinian corpuscles do not form, and their afferents do not survive, in the absence of ER81. A deficiency of dorsal root ganglia neurons expressing calretinin, a marker for neurons subserving Pacinian corpuscles, correlated with the absence of corpuscles and their afferents in Er81 null mice. These observations indicate a requirement for ER81 in the assembly of Pacinian corpuscles and the survival of the sensory neurons that innervate them.

Congenital diaphragmatic hernia associated with esophageal atresia, tracheoesophageal fistula, and truncus arteriosus in a premature newborn

The occurrence of coexisting congenital diaphragmatic hernia (CDH) and esophageal atresia (EA) with distal tracheoesophageal fistula (TEF) is extremely rare and is considered highly lethal. The combination of CDH with EA/TEF and truncus arteriosus communis (TAC) has not been reported in the literature to date. The authors describe a premature neonate with this association.

Pacinian corpuscle development involves multiple Trk signaling pathways

The development of crural Pacinian corpuscles was explored in neonatal mutant mice lacking nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) or neurotrophin-4 (NT4), or their cognate Trk receptors. Deficits of the corpuscles and their afferents were greatest in NT3, less in BDNF, and least in NT4 null mice. Deletion of NGF or p75(NTR) genes had little or no impact. No Pacinian corpuscles were present in NT3;BDNF and NT3;NT4 double or NT3;BDNF;NT4 triple null mice. Deficits were larger in NT3 than TrkC mutants and were comparable to deficits observed in TrkB or TrkA mutants. Afferents of all corpuscles coexpressed TrkA and TrkB receptors, and some afferents coexpressed all three Trk receptors. Our results suggest that multiple neurotrophins, in particular NT3, regulate the density of crural Pacinian corpuscles, most likely by regulating the survival of sensory neurons. In addition, NT3/TrkB and/or NT3/TrkA signaling plays a greater role than NT3/TrkC signaling in afferents to developing Pacinian corpuscles.

[The incidence of serious complications in neonates with birth weight < 1,500 g in the Czech Republic (in the period 2000-2002)]

OBJECTIVE

To analyse the incidence of serious complications in neonates with birth weight lower than 1,500 g in the Czech Republic in the years 2000-2002.

DESIGN

A retrospective epidemiological study.

METHODS

Frequency analysis of the data from the National Register of Neonates, administrated by the Institute of Health Information and Statistics of the Czech Republic.

RESULTS

The incidence of PIVH of level III-IV in neonates with weight of up to 1,500 g in the Czech Republic in the years 2000-2002 was 6.8-10.3%; the incidence of cPVL reached 6.4-7.6%; the incidence of ROP of level III and of a higher level was 6.6-7.9% and the incidence of NEC was between 4.3 and 5.7% of all live births. Among the surviving neonates, the percentages of those who did not have any of the PIVH, ROP, HIE or meningitis diagnoses in the reference period were as follows (according to their birth weights): 500-749g 50-63.8%; 750-999 g 69.7-74.8%; 1,000-1,499 g 86.8-91.4%; 1,500-1,999g 98-98.2%; 2,000-2,499 g 99.4-99.5%; and in the group with weight above 2,500g, the percentage was 99.9%.

CONCLUSION

The incidence of serious complications in neonates with birth weight of up to 1,500 g in the Czech Republic in the years 2000-2002 was comparable with the data stated in the literature, except for cPVL, the incidence of which was higher in the Czech Republic. The proportion of neonates, who were released and did not have any of the complications, which pose a risk to normal neurosensory development, does not virtually change for birth weights higher than 1,500 g and reaches 98 and more percent. However, among the surviving neonates with birth weight of up to 750, their proportion is mere 50-64%.

[The first experience with linezolide in treatment of nosocomial septic condition in premature neonates]

OBJECTIVE

Nosocomial infections caused by the coagulase-negative staphylococci are among the most frequent complications in an intensive care unit for neonates. The authors describe three cases of successful treatment of this complication in which the new antibiotic Linezolide was used.

DESIGN

Analysis of three clinical cases.

SETTING

Mother and Child Care Institute, Prague.

METHODS

Description of cases of nosocomial sepsis in 3 immature neonates where the usual treatment of multiresistant strains of coagulase-negative staphylococci, based on the use of Vankomycin, was not successful.

CONCLUSION

Administration of Linezolide proved to be very effective in all of the described cases. In spite of the high effectiveness and relative safety of this preparation, its precise role in the treatment of infection-related complications caused by coagulase-negative staphylococci has not yet been established. For the time being, we recommend administering this preparation only in strictly indicated cases after the usual therapy fails.

Fungal mycelium—the source of chitosan for chromatography

Mycelium of the mold Aspergillus niger was used as a raw material for the preparation of microbial chitosan. Aspergillus niger, the mold used for the production of citric acid, contains approx. 15% of chitin, which can be separated, transformed into chitosan, and used as a sorbent for chromatography. The main advantage of this material in comparison with krill chitosan is the uniformity of particle size leading to the low back-pressure in the column. The other advantage is the fact, that original fibrous structure of mycelial pellets could be stabilized before chitosan preparation by cross-linking with glutaraldehyde. The product prepared by this way -- crosslinked chitosan of uniform particle size, is highly porous, with high water regain and, as a result, low sedimentation velocity. Low sedimentation velocity is not disadvantage in chromatographic application, but may form some problems in batchwise operation. Chitosan as a polymer of glucosamine is anion exchanger in nature and the chromatographic properties of this anion exchanger was demonstrated by the chromatography of bovine blood plasma, glucose oxidase, and chicken pepsinogen. In all cases, the course of chromatography on crosslinked chitosan was compared with the chromatography on MONO Q (bovine blood plasma) or DEAE-cellulose (glucose oxidase, chicken pepsinogen) under the same protocol.

[A rare shortening of the first metatarsus of the foot and its treatment with distraction arthrodesis]

Multiple toes may develop on the medial or lateral side of the forefoot or in its middle. This may involve duplication of only the distal phalanx or the whole hallux including the metatarsal. In a duplicated big toe, the phalanx to be maintained, because short muscles of the leg are attached to it, is usually localized medially. A rare case of dysplasia of the first metatarsus, following a resection indicated in childhood for a hallux triples, is described in a 20-year-old girl. In order to remove hallux insufficiency and an overloading of the middle metatarsals, the authors decided to carry out a one-stage prolongation of the first metatarsal, using an autologous tricorticcal graft collected from the pelvis and a dynamic compression plate. No surgical treatment of the middle metatarsals was indicated because a disproportionate, short foot would result. Both the subjective and objective status of the patient at 6 months after the operation showed that the non-standard prolongation procedure was correctly indicated and allowed for physiological loading of the foot and restoration of normal walking.

Age-related changes in nigrostriatal dopaminergic function are accentuated in +/− brain-derived neurotrophic factor mice

The effects of a deletion for the brain derived neurotrophic factor (BDNF) allele (+/- BDNF) upon age-related changes in nigrostriatal dopaminergic (NSDA) function were assessed. Behavioral (beam crossing and spontaneous activity) and neurochemical (potassium-stimulated dopamine release from superfused striatum) measures were compared among Young (4-5 month), Middle (11-13 month) and Aged (19-21 month) +/- BDNF and their wild type littermate control (+/+ BDNF) mice. No statistically significant differences were obtained between +/+ and +/- BDNF mice at the Young age sampling period for any of the behavioral or neurochemical measures. Behavioral and neurochemical responses indices of NSDA function begin to diverge between +/+ and +/- Middle age BDNF mice and maximal differences were observed at the Aged period. For both movement and stereotypy times, scores obtained from +/+ mice were significantly decreased compared with +/- BDNF mice at the Aged period and center time scores of +/+ mice were decreased at both the Middle and Aged periods compared with +/- BDNF mice. Neurochemically, potassium-stimulated DA release of +/+ mice was significantly greater than +/- BDNF mice with maximal differences obtained at the Aged period. These results demonstrate marked differences in age-related changes of NSDA function between +/+ and +/- BDNF mice and suggest that the deletion of one allele for BDNF may make these mice more susceptible to age-related declines in NSDA function.

Human urine certified reference material CZ 6009: creatinine, styrene metabolites (mandelic acid and phenylglyoxylic acid)

The reference material was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to styrene. The concentrations of mandelic acid (MA), phenylglyoxylic acid (PGA), and hippuric acid (HA) in urine were determined by three modes of high-performance liquid chromatography (HPLC). For isochronous stability testing the urinary mandelic acid and phenylglyoxylic acid concentrations were followed over a 24-month period for a preliminary batch by use of HPLC. No changes of the concentration values were found. The creatinine concentration was stable for more than five years. Standard Reference Material NIST 914a Creatinine was used for traceability purposes for creatinine. Pure chemicals MA and PGA were used for traceability purposes. Control material ClinChek-Urine Control (Recipe) was analyzed simultaneously. The mean values of MA and PGA compare well with the means and fall within the control range of control samples. Results from homogeneity, stability, and traceability testing were evaluated using the statistical program ANOVA. The certified values and their uncertainties were evaluated from the results of interlaboratory comparisons, and homogeneity and stability tests. The values are unweighed arithmetical averages of accepted results and their uncertainties are combined uncertainties (coverage factor=1).

Iodine-129 and caesium-137 in Chernobyl contaminated soil and their chemical fractionation

Soil samples from areas in Belarus, Russia and Sweden contaminated by the Chernobyl accident were analysed for (129)I by radiochemical neutron activation analysis, as well as for 137Cs by gamma-spectrometry. The atomic ratio of (129)I/137Cs in the upper layer of the examined soil cores ranged from 0.10 to 0.30, with an average of 0.18, and no correlation between (129)I/137Cs ratio and the distance from Chernobyl reactor to sampling location was observed. It seems feasible to use the (129)I/137Cs ratio to reconstruct the deposition pattern of 131I in these areas. The association of (129)I and 137Cs in the Chernobyl soil and Irish Sea sediment was investigated by a sequential extraction method. Similar speciation of (129)I in the Chernobyl soil and Irish Sea sediment was found. Approximately 70% of (129)I is bound to oxides and organic matter, and 10-20% is in the readily available phase, while most of the 137Cs (73%) in Chernobyl soil remains in the extraction residue.

Iodine-129 in thyroid and urine in Ukraine and Denmark

Human thyroids collected from Gomel in Belarus, sheep thyroid from Jutland and human urine from Zealand in Denmark were analysed for 129I and 127I concentrations. The ratios of 129I/127I in human thyroid in Gomel are 2.65-11.0 x 10(-9) with an average of 7.21 x 10(-9), which is one order of magnitude higher than those from Asia and South America (10(-10)), but significantly lower than those observed in west Europe (10(-8)). A weak negative correlation (P < 0.05) between 129I/127I ratio in human thyroid and the age of the subjects was observed in Gomel. The average ratio of 129I/127I in sheep thyroids from Jutland of Denmark is 1.81 x 10(-7), which is two orders of magnitude higher than those in south hemisphere, and Asia. It is also significantly higher than those observed in other west European countries before 1984 and that in human thyroid in Gomel. The high thyroid 129I level in Jutland is attributed to the release of reprocessing plants in France and UK. The 129I/127I ratios in human urine in Zealand of Denmark are 0.86-2.86 x 10(-8). The possibility of using urine 129I to evaluate the thyroid exposure to 129I is investigated.

Quality control materials for the determination of trace elements in airborne particulate matter

The development of quality control materials for the determination of selected trace elements in air pollution studies is described. Three types of test samples were prepared for proficiency testing: (1) filters loaded with PM10 fraction of urban air particulate matter (APM) using high-volume air samplers, which were subsequently divided into smaller sections, (2) a bulk sample of APM collected in an automobile tunnel in Prague, and (3) simulated air filters loaded with APM using a wet deposition process. Homogeneity of the test samples was studied using instrumental neutron activation analysis, proton induced X-ray emission and atomic absorption spectrometry, and inductively coupled plasma optical emission spectrometry and mass spectrometry. Sufficiently homogeneous samples were prepared by all three procedures. The simulated air filters appeared to be the most suitable test samples for proficiency testing.

[Pseudo-hydrothorax in peripheral venous catheterization in an extremely premature neonate--case report]

The authors describe very rare complication (pseudopleural effusion) after peripheral venous cannulation (Introcan-W 24G3/4 through v. axilaris) in extremely premature newborn with birth weight 600 grams, which lead to worsening of patient's respiratory insufficiency. Ultrasonographic examination confirmed extrapleural process without necessity of surgical intervention. Cannula extraction and infusion interruption were followed by spontaneous regression of the complication, thereafter artificial ventilation was discontinued and baby was discharged.

Formation of supernumerary muscle spindles at the expense of Golgi tendon organs in ER81-deficient mice

ER81, a member of the ETS family of transcription factors, is essential for the formation of connections between sensory and motor neurons in the spinal cord. Mice lacking Er81 genes exhibit reduced monosynaptic sensory-motoneuron connectivity in response to muscle nerve stimulation. Proximal muscle nerve stimulation elicits fewer monosynaptic potentials than stimulation of distal nerves in hindlimbs, a deficit that is paralleled by a paucity of muscle spindles in proximal muscles (Arber et al., 2000). We examined whether a presence of spindles innervated by afferents in distal muscles correlated with the increased preservation of monosynaptic sensory-motor potentials in distal muscle nerves. Not only were spindles and Ia afferents present, but also they were supernumerary in distal muscles such as the soleus, medial gastrocnemius, and extensor hallucis longus. Concomitantly, a deficiency of Golgi tendon organs (GTOs) and Ib afferents was observed in distal muscles, as if supernumerary spindles formed at the expense of tendon organs in the absence of Er81. Thus, ER81 may be involved in mechanisms that regulate acquisition of the Ia and Ib phenotypes by subsets of proprioceptive muscle afferents. Segmental differences in muscle spindle and GTO dependence on ER81 suggest that more than one ETS transcription factor may participate in the regulation of limb proprioceptive system assembly in the mouse.

Level and origin of iodine-129 in the Baltic Sea

Environmental samples, such as seawater, seaweed, lake water, lake sediment and grass collected from the Baltic Sea area were analyzed for 129I and 127I by radiochemical neutron activation analysis. In 2000, the concentration of 129I in the seawater from Borholm and Møen in the Baltic Sea has reached 6.0 x 10(-13) and 16 x 10(-13) g/l, respectively, these are more than two orders of magnitude higher than the global fallout level. The highest value of 270 x 10(-13) g/l being found in the seawater from the Kattegat. By comparison of the level of 129I in the lake water and precipitation in this region, it is estimated that more than 95% of 129I in the Baltic Sea originates from reprocessing emissions, especially from the French nuclear fuel reprocessing plant at La Hague. More than 30% of 129I in the south Baltic and 93% in the Kattegat directly originates from the marine discharges of the European reprocessing plants.

Monitoring of occupational exposure in manufacturing of stainless steel constructions. Part I: Chromium, iron, manganese, molybdenum, nickel and vanadium in the workplace air of stainless steel welders

Exposure to workplace airborne pollutants was examined in a group of 20 workers dealing mainly with welding, polishing, drilling and assembling of stainless steel constructions. Airborne particulate matter (APM) collected using both personal and stationary samplers was analyzed by instrumental neutron activation analysis (INAA). Quality assurance procedures of both sampling and analytical stages are described. Of the elements determined, results are presented for chromium, iron, manganese, molybdenum, nickel and vanadium. The median values of element concentrations exceeded the maximum admissible limits for workplace pollutants only for chromium, while for nickel the limit was exceeded in several individual cases. Sampling of hair, nails, blood, urine and saliva to be used for biological monitoring of the exposed and control groups is also described.

Dissection of NT3 functions in vivo by gene replacement strategy

The development of the peripheral nervous system is governed in part by a family of neurotrophic factors that signal through Trk tyrosine kinase receptors. Neurotrophin 3 (NT3) ablation in mice causes a more severe neuronal phenotype than deletion of its receptor TrkC, suggesting that NT3 acts also through other non-preferred Trk receptors. To study the role of low-affinity ligand receptor interactions in vivo, we have replaced the Nt3 gene with the gene for brain-derived neurotrophic factor (BDNF), a TrkB ligand. As in NT3 and TrkC null mice, the proprioception system of these mutants failed to assemble. However, sensory fiber projections in the embryonic spinal cord suggest chemotropic effects of BDNF in vivo. In the dorsal root ganglia, the developmental dynamic of neuron numbers demonstrates that NT3 is required for activation of TrkB during neurogenesis and that TrkA is required during target tissue innervation. In the inner ear, the ectopic BDNF rescued the severe neuronal deficits caused by NT3 absence, indicating that TrkB and TrkC activate equivalent pathways to promote survival of cochlear neurons. However, specific increased innervation densities suggest unique functions for BDNF and NT3 beyond promoting neuronal survival. This mouse model has allowed the dissection of specific spatiotemporal Trk receptor activation by NT3. Our analysis provides examples of how development can be orchestrated by complex high- and low-affinity interactions between ligand and receptor families.

Installation and calibration of Kayzero-assisted NAA in three Central European countries via a Copernicus project

An account is given of the installation and calibration of k0-based NAA--assisted by the DSM Kayzero/Solcoi software package--at the KFKI-AEKI, Budapest, the NPI, Rez and the IJS, Ljubljana. Not only the calibration of the Ge-detectors and the irradiation facilities are discussed, but also other important topics such as gamma-spectrometric hard- and software, QC/QA of the IRMM-530 Al-Au flux monitor and the upgrade of the Kayzero/Solcoi code. The work was performed in the framework of a European Copernicus JRP, coordinated by the Laboratory of Analytical Chemistry, Gent, with DSM Research, Geleen, as the industrial partner.