Showing papers by "Jožef Stefan Institute published in 1995"
TL;DR: The literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts is reviewed, directing laboratories in the development of fish genotoxicity assays for water quality monitoring.
Abstract: Micronucleus assays with fish have been shown to be useful in vivo techniques for genotoxicity testing, and show potential for in situ monitoring of water quality In this paper, we review the literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts Included in the review is a description of the mechanisms for formation of micronuclei in cells, and a summary of the various techniques that have been used for micronucleus analysis in fish This review is directed to assisting laboratories in the development of fish genotoxicity assays for water quality monitoring
701 citations
TL;DR: In this article, the authors used X-ray pbotoelectron spectroscopy (XPS) to investigate the electrochemical and thermal oxidation of titanium nitride (TiN) coatings prepared by physical vapour deposition (PVD) at 200°C.
Abstract: X-ray pbotoelectron spectroscopy (XPS) has been used to investigate the electrochemical and thermal oxidation of titanium nitride (TiN) coatings prepared by physical vapour deposition (PVD) at 200°C. Electrochemical oxidation of TiN was carried out at various potentials in phthalate buffer solution (pH 5.0). Evaluation of the XPS Ti 2p and N 1s spectra showed the presence of nitride, oxynitride and oxide species in the layer formed by anodic oxidation. The electrochemical oxidation of TiN to TiO 2 proceeds through the formation of a mixed oxynitride/oxide layer, which transforms into oxide (TiO 2 ) at sufficiently positive potentials (E > 1.1 V vs. SHE). The oxidation of TiN to TiO 2 is accompanied by the formation of molecular nitrogen (N 2 ). The thickness of the oxide layer reaches ∼ 7 nm after oxidation at the highest potential (1.9 V). A complete coverage of the TiN surface by TiO 2 leads to an anodic peak in the polarization curve. On the basis of angle-resolved XPS measurements, two types of oxynitride species are identified, which are distributed differently throughout the oxidized layer. X-ray photoelectron spectroscopy depth profiles of TiN oxidized at 450°C and 600°C in an oxygen flow reveal that at the lower temperature an oxynitride layer is formed, whereas a thick TiO 2 layer appears on top of TiN at the higher temperature. The interface between the nitride and oxide phases is relatively sharp. It is suggested that the mechanism of TiN oxidation proceeds by a progressive replacement of nitrogen by oxygen. The TiN coatings can be used up to 600°C as a protective coating in an oxygen atmosphere. Valance band spectra of TiN, as well as of electrochemically and thermally oxidized TiN, are presented and discussed.
190 citations
TL;DR: The structure confirms the role of residues His 110 and His 111 as the receptors of a peptidic substrate C-terminal carboxylic group and suggests that an epoxysuccinyl fragment can be used to extend binding into primed and nonprimed substrate binding sites of a papain-like cysteine protease.
Abstract: Crystals of cysteine protease human cathepsin B inhibited with CA030 (ethyl ester of epoxysuccinyl-Ile-Pro-OH) [Murata, M., et al. (1991) FEBS Lett. 280, 307-310; Towatari, T., et al. (1991) FEBS Lett. 280, 311-315] were isomorphous to a previous published structure of cathepsin B [Musil, D., et al. (1991) EMBO J. 10, 2321-2330]. The crystal structure of the complex was refined at 2.0-A resolution to an R-value of 0.194. CA030 is well-defined in the electron density. The Ile-Pro-OH part of CA030 mimics a substrate P1' and P2' residues. The structure thus reveals for the first time a substratelike interaction in the S1' and S2' sites of a papain-like cysteine protease. The CA030 ethyl ester group occupies the S2 site. The structure confirms the role of residues His 110 and His 111 as the receptors of a peptidic substrate C-terminal carboxylic group. The structure suggests that an epoxysuccinyl fragment can be used to extend binding into primed and nonprimed substrate binding sites of a papain-like cysteine protease.
174 citations
TL;DR: The present findings suggest that magnetic resonance imaging could be useful in such a reclassification of seronegative spondyloarthritis, as well as offering considerable potential for a reappraisal of pathogenesis and therapy.
Abstract: A series of patients with clinically early inflammatory joint disease due to rheumatoid arthritis, psoriatic arthritis and Reiter's syndrome were examined by plain film radiography and magnetic resonance imaging (MRI). The spin echo T1-weighted precontrast, T2-weighted, and, especially, T1-weighted postcontrast images demonstrated distinct differences in the distribution of inflamatory changes, both within and adjacent to involved small hand joints. Two major subtypes of inflammatory arthritis were shown, thus providing a specific differential diagnosis between rheumatoid arthritis and some patients with seronegative spondyloarthritis. In particular, all the patients with Reiter's syndrome who were studied, and half of those with psoriatic arthritis, had a distinctive pattern of extra-articular disease involvement. The need for a new classification of clinical subsets in psoriatic arthritis has been recently suggested. The present findings suggest that magnetic resonance imaging could be useful in such a reclassification of seronegative spondyloarthritis, as well as offering considerable potential for a reappraisal of pathogenesis and therapy. In this series, it was also noted that juxta-articular osteoporosis on plain film did not correlate with bone marrow oedema on MRI. Hence the aetiology of this common radiographic finding also merits further consideration.
156 citations
TL;DR: The superiority of the MFES method as compared with conventional therapy was mainly attributed to the enhanced motor learning accomplished by application of MFES.
Abstract: Background and Purpose. Gait rehabilitation in patients with severe hemiplegia requires substantial effort. Preliminary studies indicate potential beneficial effects of using multichannel functional electrical stimulation (MFES) for gait rehabilitation in these patients. In this study, a new method of gait rehabilitation for nonambulatory patients with hemiplegia by means of MFES added to conventional therapy was introduced. The results of the method's application were evaluated by comparing it with conventional therapeutic methods. Subjects. The proposed rehabilitation method was tested on a group of 20 patients with severe hemiplegia secondary to cerebrovascular accident. Subjects were randomly assigned to one of two groups. One group received 3 weeks of MFES followed by 3 weeks of conventional therapy. The other group received 3 weeks of conventional therapy followed by 3 weeks of MFES. Methods. The effects of each therapeutic method were evaluated by measurements of temporal-distance variables and ground reaction forces and by assessment of each subject's physical status according to the Fugl-Meyer evaluation scale. Results. There was improved performance of the subjects during MFES combined with conventional therapy as compared with conventional therapy alone. Conclusion and Discussion. The superiority of the MFES method as compared with conventional therapy was mainly attributed to the enhanced motor learning accomplished by application of MFES. These results, however, are preliminary, and further research is needed.
155 citations
TL;DR: In this paper, the oxidation behavior of the CrN and TiN hard coatings prepared by reactive sputtering at 200 °C was studied using X-ray photoelectron spectroscopy.
Abstract: The oxidation behaviour of the CrN and TiN hard coatings prepared by reactive sputtering at 200 °C was studied using X-ray photoelectron spectroscopy. The formation of thin surface overlayers on top of nitride coatings was observed even at room temperature. At elevated temperatures the mechanism of nitride oxidation proceeds by a progressive displacement of nitrogen by oxygen. At sufficiently high temperatures a tendency towards phase separation between the nitride and oxide is observed, resulting in the formation of Cr 2 O 3 and TiO 2 layers, respectively.
134 citations
TL;DR: A cDNA clone encoding human procathepsin B was expressed at a high level in Escherichia coli using a T7 polymerase expression system, resulting in the formation of insoluble cytoplasmic protein aggregates (inclusion bodies).
Abstract: A cDNA clone encoding human procathepsin B was expressed at a high level in Escherichia coli using a T7 polymerase expression system, resulting in the formation of insoluble cytoplasmic protein aggregates (inclusion bodies). The recombinant product was solubilized and renatured by refolding and reoxidation. The proenzyme was subsequently processed with pepsin to produce an enzymically active enzyme. By systematic variation of the parameters influencing the folding, formation of disulphide bonds, and processing of procathepsin B to the catalytically active mature form, a simple renaturation procedure was designed, allowing the production of about 3 mg purified active cathepsin B/l E. coli culture broth. The enzyme obtained in this way consists of a single chain and, as a consequence of pepsin treatment, possesses a three-amino-acid extension at its N-terminus. The enzyme has similar kinetic and immunological properties to native human cathepsin B.
121 citations
TL;DR: In this article, the free energy expansion in terms of order parameter takes into account interactions between nearest and next nearest smectic layers, and allows for competing interactions, and the structure of the frustrated Sm C*α phase is obtained.
Abstract: In a discrete phenomenological description of tilted smectic phases, the order parameter, which describes the magnitude and the direction of the tilt of the molecules, is defined for each smectic layer. The free energy expansion in terms of order parameter takes into account interactions between nearest and next nearest smectic layers, and allows for competing interactions. By minimizing the free energy of the system the structure of the frustrated Sm C*α phase is obtained.
119 citations
TL;DR: The kinetics of pH-induced inactivation of human cathepsins B and L was studied by conventional and stopped-flow methods and found to be an irreversible, first-order process.
Abstract: The kinetics of pH-induced inactivation of human cathepsins B and L was studied by conventional and stopped-flow methods. The inactivation of both enzymes was found to be an irreversible, first-order process. The inactivation rate constants increased exponentially with pH for both enzymes. From log kinac vs pH plots, 3.0 and 1.7 protons were calculated to be desorbed for pH-induced inactivation of cathepsins L and B. Cathepsin B was thus substantially more stable than cathepsin L (approximately 15-fold at pH 7.0 and 37 degrees C). Cathepsin B was efficiently inhibited by cystatin C at pH 7.4, whereas the inhibition by stefin B and high molecular weight kininogen was only moderate. In contrast, cathepsin L was efficiently inhibited by both chicken cystatin and stefin B at this pH kass approximately 3.3 x 10(7) m-1 s-1).
118 citations
TL;DR: Human cathepsin C appears to differ qualitatively from other cysteine proteinases of different origin, explained by a sequential cooperative interaction model, where an enzyme molecule can bind up to four substrate molecules but where only the binary enzyme-substrate complex is catalytically active.
116 citations
TL;DR: The three-dimensional solution structure of recombinant human stefin A has been determined by a simulated annealing protocol using a total of 1113 distance and angle constraints obtained from 1H and 15N HMR spectroscopy.
TL;DR: Arsenic species in arsenic accumulating mush- rooms (Sarcosphaera coronaria, Laccaria amethystina, Sarcodon imbricatum, Entoloma lividum,Agaricus haemorrhoidaius, Agaricus placomyces, Lycoperdon perlatum) were determined.
Abstract: Arsenic species in arsenic accumulating mush- rooms (Sarcosphaera coronaria, Laccaria amethystina, Sarcodon imbricatum, Entoloma lividum, Agaricus haemorrhoidaius, Agaricus placomyces, Lycoperdon perlatum) were determined. HPLC/ICP MS and ion-exchange chromatogra- phy–instrumental neutron activation analysis (NAA) combinations were used. The remarkable accumulator Sarcosphaera coronaria (up to 2000 mg As kg−1 dry wt) contained only methylarsonic acid, Entoloma lividum only arsenite and arsenate. In Laccaria amethystina dimethylarsinic acid was the major arsenic compound. Sarcodon imbricatum and the two Agaricus sp. were found to contain arsenobetaine as the major arsenic species, a form which had previously been found only in marine biota. Its identification was confirmed by electron impact MS.
TL;DR: Electron spin resonance and alternating current susceptometry measurements on tetrakis(dimethylamino)ethylene-C 60 (TDAE-C60) show a direct coupling between spin and merohedral degrees of freedom, suggesting a microscopic origin for the observed spinglass behavior of the magnetic state.
Abstract: Spin ordering in the low-temperature magnetic phase is directly linked to the orientational ordering of C(60) molecules in organically doped fullerene derivatives. Electron spin resonance and alternating current susceptometry measurements on tetrakis(dimethylamino)ethylene-C(60) (TDAE-C(60)) (Curie temperature T(c) = 16 kelvin) show a direct coupling between spin and merohedral degrees of freedom. This coupling was experimentally demonstrated by showing that ordering the spins in the magnetic phase imprints a merohedral order on the solid or, conversely, that merohedrally ordering the C(60) molecules influences the spin order at low temperature. The merohedral disorder gives rise to a distribution of pi-lectron exchange interactions between spins on neighboring C(60) molecules, suggesting a microscopic origin for the observed spinglass behavior of the magnetic state.
TL;DR: The concentrations of cathepsins D, B, H and L and stefins A and B measured in head and neck tumours, were independent of standard clinical and histological prognostic factors and significant correlation of tumour tissue values was observed.
Abstract: In cytosols of tumour and normal tissue of 53 patients suffering from head and neck carcinoma cathepsins D, B, H and L were measured using quantitative immunoreactive assays (ELISA). The values of cathepsins D, B and L were significantly higher in tumour tissue, whereas cathepsin H concentration was lower in tumour than in normal tissue. Median cathepsin D values were 27 pmol (tumour tissue) vs. 12 pmol (normal tissue) per mg of total protein, median cathepsin B values were 1.25 micrograms/mg (tumour tissue) vs. 0.23 micrograms/mg (normal tissue) and median cathepsin L values were 39.8 ng/mg (tumour tissue) vs. 20.0 ng/mg (normal tissue). Median cathepsin H values were 1.05 micrograms/mg and 2.20 micrograms/mg for tumour and normal tissue, respectively. Additionally, stefin A and stefin B were measured in tumour and normal tissue samples. In contrast to the cathepsins, the concentrations of these inhibitors of cysteine proteinases was not significantly different between tumour and normal samples. The concentrations of cathepsins D, B, H and L and stefins A and B measured in head and neck tumours, were independent of standard clinical and histological prognostic factors. Significant correlation of tumour tissue values was observed between cathepsins B and L and between both stefins.
TL;DR: A possible defensive role for the host's cystatins after parasite infection is suggested, and may be of use for the design of new therapeutic drugs.
TL;DR: A multiple alignment of the deduced cathepsin C sequence of 233 residues which, by analogy to other cysteine proteinases, corresponds to the mature protein, confirms that human cathePSin C belongs to the papain superfamily.
TL;DR: In this paper, the plasma beam sputtering process was used to prepare CrN and TiN hard coatings on steel, sapphire and alumina Superstrate substrates at a temperature of 200 °C.
Abstract: The plasma beam sputtering process was used to prepare CrN and TiN hard coatings on steel, sapphire and alumina Superstrate substrates at a temperature of 200 °C. The microstructural characteristics, coating morphology, interfacial properties, microhardness and internal stresses were studied for coatings 3 μm thick. Their oxidation behaviour in an oxygen flow in a tube furnace was studied at temperatures up to 600 °C for TiN and up to 800 °C for CrN coatings. The initial stage of oxidation of TiN and CrN coatings 350 nm thick was also studied by continuous in-situ electrical resistivity measurements. This measurement technique offers high reproducibility and accuracy, so can be used to study oxidation for all types of hard coating, and especially for new multilayer and duplex coatings. Weight gain measurements and Auger electron spectroscopy depth profile analyses of oxidized stoichiometric CrN coatings showed that oxidation in an oxygen flow at 800 °C for 4 h induced the growth of a stable Cr2O3 film. The thickness of this oxide film was only 15% of the total (3 μm) coating thickness. The surface morphology and small roughness changes — as also observed after a long-term test at 800 °C for 200 h in oxygen — indicated that a stoichiometric CrN coating with the measured properties can be successfully used as a hard and oxidation-resistant coating in industrial practice, even if the working temperatures are higher than 750 °C.
TL;DR: In this paper, the effect of dopants on the magnetic properties of MnZn ferrites for high frequency power supplies was investigated and it was found that the combined effect of Sn/sup 4+/, Ti/sup 6+/ and Ta/sup 5+/ was found to increase the grain boundary resistivity in the ferrites studied and remarkably decrease the power loss at higher frequencies.
Abstract: The effect of additions on the magnetic properties of MnZn ferrites for high frequency power supplies was studied. The investigation revealed that various combinations of dopants added to the ferrite modify the grain boundary resistivity and the magnetic permeability spectra at constant microstructure. Particularly, the combined effect of Sn/sup 4+/, Ti/sup 4+/ and Ta/sup 5+/ was found to increase the grain boundary resistivity in the ferrites studied and remarkably decrease the power loss at higher frequencies. >
TL;DR: In this article, the authors used perovskite-type oxides as humidity sensors and measured the conductance and susceptance of the sensors versus relative humidity at 400 Hz.
Abstract: Ceramic materials based on perovskite-type oxides can be used as humidity sensors. Thick film sensors based on (Ba0.5Sr0.5TiO3 material doped with MgO were prepared by printing and firing thick film pastes on 96% alumina substrates. Fritless platinum paste was used as the electrode material. The a.c. respone of the thick film humidity sensors at 20–80% relative humidity and 10–60 °C was measured. The conductance and susceptance of the sensors versus relative humidity were measured at 400 Hz. The capacitive component of the sensors impedance at low humidity (20–4-% relative humidity) has negative temperature characteristics and obeys the Curie-Weiss law. This indicates the dielectrical properties of the adsorbed water on the perovskite sensor surface. The conductance is logarithmically linear. At high humidity a positive temperature characteristic of the capacitive component was observed. An inversion between these two characteristics was detected at about 40% relative humidity for all measured temperatures.
TL;DR: The results showed that each of the radionuclides had its own distribution pattern in this environment, while U concentrations were high in the valley of the confluence of the Todrascica and Brebovscica streams close to the former yellow-cake production plant in Todraz, and then decreased downstream as mentioned in this paper.
Abstract: Samples ofHypogymnia physodeswere transplanted to the environment of the former uranium mine at Zirovski vrh, Slovenia, for two exposure experiments. The levels of the long-lived radionuclides,238U,226Ra and210Pb in lichen material were measured after 4 and 7 months in the first experiment, and 4, 8 and 12 months in the second, and compared with the levels in lichens growingin-situfrom the same sampling locations. They were also compared with the nuclide levels found in air particulates by gamma spectrometry obtained at the regular site monitoring stations. The results showed that each of the radionuclides had its own distribution pattern in this environment. The highest226Ra levels were found in lichens in the near vicinity of the dry-tailings pile, while U concentrations were high in the valley of the confluence of the Todrascica and Brebovscica streams close to the former yellow-cake production plant in Todraz, and then decreased downstream.210Pb was the most uniformly distributed radionuclide and exhibited the highest level. The results also confirm that active biomonitoring with transplanted lichens can be a useful and cheap supplement to instrumental air pollution monitoring.
TL;DR: In this article, the tool life, surface quality of the products and wear mechanisms were studied for the following polished tools (max. diameter, 210 mm): a mould for Al-Si12 die casting of small components of compressors; a combined cold forming and cutting die for mass production of covers for the heating plate of an electric stove; a cold forming deep drawing die for the production of a halogen lamp housing in the electric light industry; a tool set for automatic gradual deep drawing of fancy goods for the shoe and leather industry, and a deep-drawing die for
Abstract: CrN (PVD) coatings, deposited at 200 °C in plasma beam sputtering apparatus, were used for selected applications in industry. Using CrN coating, we improved two types of tool: moulds for Al alloy die casting (made of AISI H11 tool steel) and cold forming tools (made of AISI D2 and D3 tool steel). For the first group of tools, it was important that the CrN coating could be successfully used as a hard, oxidation- and corrosion-resistant coating at working temperatures of up to 800 °C; for the second group of tools, the low tempering temperature dictates deposition at 200 °C. The tool life, surface quality of the products and wear mechanisms were studied for the following polished tools (max. diameter, 210 mm): a mould for Al-Si12 die casting of small components of compressors; a combined cold forming and cutting die for mass production of covers for the heating plate of an electric stove; a cold forming deep drawing die for the production of a halogen lamp housing in the electric light industry; a tool set for automatic gradual deep drawing of fancy goods for the shoe and leather industry; a deep drawing die for mass production of the covers of electric motors. All the results show that a CrN coating 4.5–5.5 μm thick with a Cr intermediate layer 0.2 μm thick between the substrate and the coating improved the technological processes and resulted in a noticeable improvement in performance tests. Increased tool life, a higher quality of surface finish of the products and high reliability of CrN coated tools in production were regularly observed during long-term performance tests.
TL;DR: This paper analyses various phenomena and problems observed in experiments in behavioural cloning in several domains: piloting, driving a container crane, production scheduling and pole-balancing and derives some elements of an emerging methodology for behavioural cloning.
TL;DR: In this paper, structural transformations at the electrochemical interface induced by variation of the electrode potential are overviewed, ranging from the transitions in adsorbed layers to surface reconstruction, and the effect of reconstruction on the double-layer capacitance.
TL;DR: For the first time, three different stefins, A, B and C, have been isolated from a single species and the complete amino acid sequence of bovine stefin A was determined.
TL;DR: The origin and temporal variation in composition of sedimented particulate organic matter (POM) in the Gulf of Trieste (northern Adriatic) was studied over the year with special reference to the composition and sedimentation of macroaggregates in summer of 1991 using sediment traps.
Abstract: The origin and temporal variation in composition of sedimented particulate organic matter (POM) in the Gulf of Trieste (northern Adriatic) was studied over the year with special reference to the composition and sedimentation of macroaggregates in summer of 1991 using sediment traps.
TL;DR: A computer-based expert system for the evaluation of research and development projects and in the process of evaluation and selection of projects submitted to the annual competition for funds is presented.
TL;DR: The main objective of this work was to develop and use a binucleated method which depends on the cytokinesis blocking of hepatic cells in fish to enable the scoring of micronuclei in cells that have completed only one division after genotoxic insult.
Abstract: The main objective of this work was to develop and use a binucleated method which depends on the cytokinesis blocking of hepatic cells in fish to enable the scoring of micronuclei in cells that have completed only one division after genotoxic insult. The use of this novel technique in a study of the influence of some pollutants in vitro (selenium, mercury, methylmercury, and their mixtures) allows evaluation of the risk from exposure to these water pollutants under field and laboratory conditions. The frequencies of micronuclei in trout hepatic cells in vitro were elevated in a dose-dependent manner when compared to the relevant controls. Addition of Se(IV) reduced the frequencies of micronuclei in treatments with both forms of mercury. Inorganic mercury was found to be partly methylated when exposed to trout liver cells in vitro. The potential contribution of the fish binucleated hepatic technique to the toxicity assessment of the chemicals investigated is discussed.
TL;DR: In this paper, a dual-beam thermal lens spectrometer was used to detect trivalent and hexavalent chromium species separated as anions on a Dionex HPIC CS5 column.
TL;DR: In this article, 27 laboratories from around the world agreed to participate in an intercomparison exercise for total Hg and methyl Hg (MMHg) in pristine lake water.
Abstract: Twenty-seven laboratories from around the world agreed to participate in an intercomparison exercise for total Hg (Hgt) and methyl Hg (MMHg) in pristine lake water. Unfiltered samples from a remote brown water lake in northern Wisconsin (USA) were collected into acid cleaned Teflon® bottles using ultra-clean sample handling techniques. The samples were acidified in the field with 0.4% by volume of pre-analyzed HQ (12N; <5 pg Hg/mL), and sent to the primary reference laboratory (PRL) by overnight mail. Within one week of receipt, the samples were randomized, and 10% analyzed for Hgt and MMHg at the PRL to verify the homogeneity of the set. Each participating laboratory was then sent 3 randomly selected 1 L bottles, while the PRL retained 30, and the secondary reference laboratory (SRL) retained 12 samples. The participating laboratories were asked to analyze each bottle in triplicate for both Hgt and MMHg, reporting all QA data including blanks, spike recoveries, and detection limits. The PRL analyzed samples in triplicate at both the beginning and the end of the analytical window, to provide a controlled estimate of any changes in concentration or speciation over that time. Of the 23 laboratories that returned results, 18 utilized Br CI oxidation, gold trapping, and cold vapor atomic fluorescence (CVAFS) detection for Hgt-Four laboratories reported similar techniques, varying either in detector (cold vapor atomic absorption), or wet chemistry. Only 16 laboratories reported MMHg results, with 15 using a variation of the aqueous phase ethylation, GC separation, and CVAFS detection technique. The results show good convergence between the participating labs for both Hgt and MMHg. For Hgt 18 of 23 labs reported means within 20% of the consensus value and PRL results (1.27 ± 0.18 ng/L and 1.27 ± 0.14 ng/L respectively). For MMHg, 13 of the 16 labs reported results within 20% of either the consensus value (0.420 ± 0.055 ng/L) or the PRL value (0.446 ± 0.041 ng/L).