Showing papers by "Jožef Stefan Institute published in 2000"
TL;DR: The various physiological roles of mammalian lysosomal papain-like cysteine proteases as well as their mechanisms of action and the regulation of their activity are reviewed and discussed.
817 citations
TL;DR: In this article, the surface charge on some commercially available zinc oxide powders in aqueous solution has been studied and the point of zero charge and charge reversal were found to be a direct function of the zinc and sulphate ions' concentration in the supernatant.
Abstract: The surface charge on some commercially available zinc oxide powders in aqueous solution has been studied. Aqueous suspensions of zinc oxide could not be stabilized electrostatically because of the decreasing pH of suspensions in the region between 7.2 and 12 as a result the transformation of colloidal Zn(OH)2(S) particles to Zn(OH)2(aq) ions. The major cationic impurity in the zinc oxide powders is lead, whereas in the aged suspensions of the same powders, zinc and sulphate ions dominate. These ions have the the most significant effect in creating an electrical double layer shell around the zinc oxide particles. The effect of these ions on the surface potential of zinc oxide was studied and the point of zero charge and charge reversal were found to be a direct function of the zinc and sulphate ions' concentration in the supernatant.
461 citations
TL;DR: Since a special Y-TZP grade containing a small amount of alumina exhibited the highest damage tolerance and superior stability in an acidic environment, this material shows considerable promise for dental applications.
Abstract: This work was undertaken to evaluate the effects of dental grinding and sandblasting on the biaxial flexural strength and Weibull modulus of various Y-TZP ceramics containing 3 mol% yttria. In addition, the susceptibility of pristine and mechanically treated materials to low-temperature degradation under the conditions adopted for testing the chemical solubility of dental ceramics was investigated. The results revealed that surface grinding and sandblasting exhibit a counteracting effect on the strength of Y-TZP ceramics. Dental grinding lowered the mean strength and Weibull modulus, whereas sandblasting provided a powerful method for strengthening, but at the expense of somewhat lower reliability. The finest-grained material exhibited the highest strength after sintering, but it was less damage tolerant than tougher, coarse-grained materials. Upon extraction with the acetic acid solution and the ammonia solution, a significant amount of tetragonal zirconia had transformed to monoclinic, but extensive microcracking and attendant strength degradation had not yet occurred. Standard grade Y-TZP ceramics are more resistant in an alkaline than in an acidic environment, and there was a strong grain-size dependence of the diffusion-controlled transformation. Since a special Y-TZP grade containing a small amount of alumina exhibited the highest damage tolerance and superior stability in an acidic environment, this material shows considerable promise for dental applications.
385 citations
TL;DR: The passive film formed by electrochemical oxidation on TiAlV alloy in physiological solution was studied using X-ray photoelectron spectroscopy and EIS to characterise electronic properties of passive films over seven decades of frequency and a link between electronic, electrochemical and physiochemical properties was established.
314 citations
01 Jan 2000
TL;DR: This book presents the most recent research advances in the theory, design, control and application of robotic systems, which are intended for a variety of purposes such as manipulation, manufacturing, automation, surgery, locomotion and biomechanics.
Abstract: From the Publisher:
This book presents the most recent research advances in the theory, design, control and application of robotic systems, which are intended for a variety of purposes such as manipulation, manufacturing, automation, surgery, locomotion and biomechanics. The issues addressed are fundamentally kinematic in nature, including synthesis, calibration, redundancy, force control, dexterity, inverse and forward kinematics, kinematic singularities, as well as over-constrained systems. Methods used include line geometry, quaternion algebra, screw algebra, and linear algebra. These methods are applied to both parallel and serial multi-degree-of-freedom systems. The results should interest researchers, teachers, and students, in fields of engineering and mathematics related to robot theory, design, control and application.
303 citations
TL;DR: The results of the BCR three-step sequential extraction procedure indicate high Ni and Zn mobility in the sludge analysed, which means the investigated sewage sludge could not be used in agriculture.
236 citations
TL;DR: Based on studies of several toxin multigene families at the gene level the picture is emerging that most have been functionally diversified by gene duplication and adaptive evolution.
211 citations
TL;DR: Increases in total Hg and MeHg in the estuary demonstrate the remobilization of Hg, presumably as HgS dissolution and recycling, and high Hg levels persist into the Gulf.
207 citations
Journal Article•
TL;DR: The results reveal a correlation between high levels of extracellular cysteine proteinase inhibitors and short survival in patients with colorectal cancer, and the data thus support previous studies suggesting a contributing role of protease inhibitors in the progression of cancer.
Abstract: The levels of cysteine proteinase inhibitors stefin A, stefin B, and cystatin C were determined using ELISAs in sera obtained preoperatively from 345 patients with colorectal cancer and in control sera from 125 healthy blood donors. The levels of stefin A and cystatin C were found to be moderately increased in patient sera (1.4-fold and 1.6-fold, respectively; P < 0.0001), whereas the level of stefin B remained statistically unchanged when compared with controls. The medians were 4.3 ng/ml versus 3.2 ng/ml for stefin A, 1.2 ng/ml versus 1.7 ng/ml for stefin B, and 679 ng/ml versus 425 ng/ml for cystatin C. In patient sera, a weak correlation of cystatin C with age (r = 0.34; P < 0.001) and gender (P = 0.01) was found. Stefin A and cystatin C levels were independent of Dukes' stage, whereas stefin B correlated significantly with Dukes' stage, its level being the highest in stage D (P < 0.007). Stefin B and cystatin C correlated with survival, whereas stefin A was not a significant prognostic factor in this study. Using medians as cutoff values, patients with high levels of stefin B and patients with high levels of cystatin C exhibited a significantly higher risk of death than those with low levels of inhibitors (hazard ratio = 1.6; 95% confidence interval, 1.2-2.2; P = 0.002 for stefin B; hazard ratio = 1.3; 95% confidence interval, 1.0-1.8; P = 0.04 for cystatin C). Our results reveal a correlation between high levels of extracellular cysteine proteinase inhibitors and short survival in patients with colorectal cancer, and the data thus support previous studies suggesting a contributing role of protease inhibitors in the progression of cancer.
177 citations
TL;DR: Significant higher cystatin C concentrations were found in asthmatic patients compared to controls which suggests its role in the pathogenesis of asthma, and supports the need for the evaluation of cyStatin C as a marker of glomerular filtration rate determination in asthma.
171 citations
TL;DR: The cathepsin B/cystatin C complex was found to be less abundant in sera of patients with malignant tumors than in those with benign diseases or in healthy controls, suggesting an imbalance between the enzyme and its inhibitor in cancer patients.
Abstract: Cathepsins B, H and L have been shown to participate in processes of tumor growth, vascularization, invasion and metastasis. Their levels in tumor tissue extracts can provide useful clinical information to predict disease-free and overall survival in breast, lung, colorectal, brain and head and neck cancer patients. Recently we have found that both cysteine cathepsins and their endogenous protein inhibitors stefins and cystatin C can also predict prognosis when measured extracellularly. In melanoma and colorectal cancer patients high serum levels of cathepsins B and H correlated with shorter survival. Similarly, increased extracellular levels of stefins A and B and cystatin C correlated significantly with high risk of adverse outcome in cancer patients. However, the cathepsin B/cystatin C complex was found to be less abundant in sera of patients with malignant tumors than in those with benign diseases or in healthy controls, suggesting an imbalance between the enzyme and its inhibitor in cancer patients.
TL;DR: In this article, a long-term monitoring of the terrestrial soil-vegetation-herbivore-carnivore food chain with regard to accumulation and transformation processes was studied in areas of Slovenia contaminated with mercury to differing degrees, as well as uncontaminated areas.
Abstract: Total mercury and methylmercury concentrations from long-term monitoring of the terrestrial soil-vegetation-herbivore-carnivore food chain with regard to accumulation and transformation processes were studied in areas of Slovenia contaminated with mercury to differing degrees, as well as uncontaminated areas. Assessment of the inhaled and ingested contribution of mercury from the environment in roe deer (Capreolus capreolus L.), the selected wild mammal species living in these areas, showed that while the ratio between these two routes of uptake is relatively constant, food intake of mercury in roe deer is much more important than inhaled mercury, which represents only up to 0.2% of ingested Hg. Although the plant species comprising roe deer foodstuffs were not active accumulators of mercury from soil or air, vegetation mediates significant transfer of Me-Hg to herbivores, and this becomes subject to further accumulation in the higher trophic levels of this food chain. Besides roe deer other bioindicators...
TL;DR: This work has investigated whether deep coagulation of dermal collagen, similar to that observed with the CO2 laser, could be achieved with repetitive Er:YAG laser exposures.
Abstract: Background and Objective: Er:YAG lasers are known to effectively ablate human skin with minimal thermal damage to subjacent dermal tissue. We have investigated whether deep coagulation of dermal collagen, similar to that observed with the CO2 laser, could be achieved with repetitive Er:YAG laser exposures. Study Design/Materials and Methods: Skin on the back of a SpragueDawley rat in vivo was irradiated with sequences of 1‐10 Er:YAG laser pulses at a repetition rate of 10 or 33 Hz and single-pulse fluences from 0.8 to 1.4 J/cm 2 . The resulting lesions were biopsied within 1 hour after laser exposure, and the histologic sections were examined by using optical microscopy. Results: The depth of dermal collagen denaturation increases dramatically when 3‐10 low-fluence Er:YAG laser pulses are stacked at a repetition rate of 10 or 33 Hz. Conclusion: Coagulation of dermal collagen deeper than 200 mm below the epidermal-dermal junction is feasible by using the appropriate settings of a repetitive Er:YAG laser. Lasers Surg. Med. 26:215‐222, 2000. © 2000 Wiley-Liss, Inc.
Book•
25 Sep 2000TL;DR: This work applies machine learning, in particular regression tree induction, to biological and chemical data on the water quality of Slovenian rivers that predict values of chemical parameters fromData on the presence of bioindicator taxa at the species and family levels.
Abstract: We address the problem of inferring chemical parameters of river water quality from biological ones. This task is important for enabling selective chemical monitoring of river water quality. We apply machine learning, in particular regression tree induction, to biological and chemical data on the water quality of Slovenian rivers. Regression trees are constructed that predict values of chemical parameters from data on the presence of bioindicator taxa at the species and family levels.
TL;DR: The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9/65/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dieLECTric behavior as a function of the dc electric field.
Abstract: The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9/65/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dielectric behavior as a function of the dc electric field. In zero field a paraelectric-to-glass, and, in a high enough dc field, a glass-to-ferroelectriclike crossover in the temperature dependence of the nonlinear response have been observed. Both crossovers agree with the predictions of the spherical random-bond--random-field model. Relaxors thus undergo in zero field a transition to a spherical glass, while above the critical field a transition into a ferroelectric state occurs.
TL;DR: It is debatable which element is the more hazardous for the general population as concerns neurotoxicity, as the highest Hg concentrations were found in endocrine glands and kidney cortex, regardless of the group.
TL;DR: It seems that the strong enrichment of oxidized chromium and Mo in the passive layer, andStrong enrichment of Mo and depletion of iron at the metal surface underneath the Passive layer, are responsible for the outstanding corrosion resistance of orthopedic stainless steel in physiological solution.
Abstract: The passive film formed by electrochemical oxidation on two different stainless steels differing in molybdenum (Mo) content in physiological solution with and without the addition of complexing agent, i.e., citrate, was studied using X-ray photoelectron spectroscopy. The alloys were polarized at different oxidation potentials in the electrochemical chamber attached to the spectrometer. Thus, the composition of the film formed by oxidation was analyzed by X-ray photoelectron spectroscopy without prior exposure to air (quasi in situ). The passive film formed in physiological solution consists of two predominant oxides, i.e., chromium and iron oxides. Oxides of alloying elements nickel and Mo are also detected in the film. It seems that the strong enrichment of oxidized chromium and Mo in the passive layer, and strong enrichment of Mo and depletion of iron at the metal surface underneath the passive layer, are responsible for the outstanding corrosion resistance of orthopedic stainless steel in physiological solution. Commercial AISI 304 is not suitable for orthopedic applications. The addition of complexing agent affects significantly the passivation behavior of orthopedic stainless steel, because it changes the distribution of the elements within the passive layer and at the metal surface underneath.
TL;DR: This article presents an approach to the development and application of qualitative hierarchical decision models that is based on DEX, an expert system shell for multi-attribute decision support, and highlights and justifies the importance of knowledge presentation and option analysis methods for practical decision-making.
TL;DR: The crystal structure of the catalytic unit of a primase enzyme, that of a approximately 320 residue fragment of Escherichia coli primase, determined at 2.9 A resolution, is presented, which shows a TOPRIM domain that is strikingly similar in its structure to that of corresponding domains in DNA topoisomerases, but is unrelated to the catalyst centers of other DNA or RNA polymerases.
TL;DR: Cathepsin X, purified to homogeneity from human liver, is a single chain glycoprotein with a molecular mass of approximately 33 kDa and pI 5.1-5.3 and found to be a carboxypeptidase with preference for a positively charged Arg in P1 position.
Abstract: Cathepsin X, purified to homogeneity from human liver, is a single chain glycoprotein with a molecular mass of < 33 kDa and pI 5.1‐5.3. Cathepsin X was inhibited by stefin A, cystatin C and chicken cystatin (Kia 1.7‐15.0 nm), but poorly or not at all by stefin B (Ki . 250 nm) and l-kininogen, respectively. The enzyme was also inhibited by two specific synthetic cathepsin B inhibitors, CA-074 and GFG-semicarbazone. Cathepsin X was similar to cathepsin B and found to be a carboxypeptidase with preference for a positively charged Arg in P1 position. Contrary to the preference of cathepsin B, cathepsin X normally acts as a carboxymonopeptidase. However, the preference for Arg in the P1 position is so strong that cathepsin X cleaves substrates with Arg in antepenultimate position, acting also as a carboxydipeptidase. A large hydrophobic residue such as Trp is preferred in the P1 0 position, although the enzyme cleaved all P1 0 residues investigated (Trp, Phe, Ala, Arg, Pro). Cathepsin X also cleaved substrates with amide-blocked C-terminal carboxyl group with rates similar to those of the unblocked substrates. In contrast, no endopeptidase activity of cathepsin X could be detected on a series of o-aminobenzoic acid-peptidyl-N-[2,-dinitrophenyl]ethylenediamine substrates. Furthermore, the standard cysteine protease methylcoumarine amide substrates (kcat /Km < 5.0 10 3 m 21 ·s 21 ) were degraded < 25-fold less efficiently than the carboxypeptidase substrates (kcat /Km < 120.0 10 3 m 21 ·s 21 ).
TL;DR: In this article, high-fluorinated graphites have been synthesized by using elemental fluorine under pressure and high oxidation state complex fluoride, K 2 NiF 6 or KAgF 4 in anhydrous hydrogen fluoride.
TL;DR: The purpose of this study was to determine optimal spurt duration, τs, and optimal delay, τd, between the cryogen spurt and laser pulse when using CSC in treatment of port wine stain birthmarks.
Abstract: Background and Objective
In dermatologic laser therapy, cryogen spray cooling (CSC) is a means to protect the epidermis while leaving dermal structures susceptible to thermal damage. The purpose of this study was to determine optimal spurt duration, τs, and optimal delay, τd, between the cryogen spurt and laser pulse when using CSC in treatment of port wine stain birthmarks.
Study Design/Materials and Methods
A finite difference method is used to compute temperature distributions in human skin in response to CSC. Optimal τs and τd are determined by maximizing the temperature difference between a modeled basal layer and an imaginary target chromophore.
Results
The model predicts an optimal τs of 170–300 msec and approximately 400 msec for shallow (150 μm) and deeper (400 μm) targets, respectively. Spraying for longer than the optimal τs does not critically impair cooling selectivity. For a spurt duration of 100 msec, optimal delays are 5–10 msec and 25–70 msec for a shallow and deep basal layer, respectively.
Conclusion
In the absence of knowledge about the lesion anatomy, using a τs of 100–200 msec and no delay is a good compromise. A delay is justified only when basal layer and target chromophore are relatively deep and the optimal spurt duration cannot be applied, e.g., to avoid frostbite. Lasers Surg. Med. 27:165–170, 2000. © 2000 Wiley-Liss, Inc.
TL;DR: A method by which it is possible to characterize the membranes of biological samples on the basis of the EPR spectral lineshape simulation of membrane-dissolved nitroxide spin probes is described, and a new way of characterizing the goodness of fits is introduced.
TL;DR: It was found that micronucleus induction in fish erythrocytes increased not only in a dose-dependent manner but also in a time-dependent way, compared with negative (tap water) and positive (10 ppm benzene) control groups.
TL;DR: The monomer sequence is clearly devoid of typical cystatin structure elements and has no similarity to any other known cysteine proteinase inhibitors but bears some similarity to a lectin-like family of proteins from mushrooms.
TL;DR: The structure ofCathepsin X exhibits a binding surface that will assist in the design of specific inhibitors of catheps in X as well as of cat hepsin B and thereby help to clarify the physiological roles of both proteases.
TL;DR: In this article, the reactivity of AlN powder in diluted inorganic acids was studied by measuring the pH and temperature during its hydrolysis, and the results showed that at very low starting pH (pH ∼ 1) no reaction was observed, regardless of the acid used.
Abstract: The reactivity of AlN powder in diluted inorganic acids was studied by measuring the pH and temperature during its hydrolysis. At very low starting pH (pH ∼1) no reaction was observed, regardless of the acid used. In contrast, in a less acidic environment, i.e., at higher pH values (pH ∼3), the reaction was fast enough to reveal the influence of different acids on the hydrolysis reaction. Monoprotonic acids which are completely dissociated (HCl, HF, HNO 3 ), and form water-soluble salts with aluminum, did not influence the hydrolysis reactions. In the presence of incompletely dissociated diprotonic H 2 SO 4 and H 2 CO 3 acids which form water-soluble salts with aluminum, the reaction was hindered but not prevented. In the presence of phosphoric acid the hydrolysis was prevented at room temperature, presumably because of the formation of insoluble phosphates on the powder surface. At elevated temperatures their solubility was substantial, and the reactivity of AIN powder in a diluted hot phosphoric acid was reestablished. In the presence of silicic acid the reaction was suppressed at both room and elevated temperatures, which was also ascribed to the formation of insoluble silicates. The adsorption of silicate anions onto the powder surface was confirmed by chemical analysis and zeta potential measurement. Using DRIFT measurements, however, the presence of Si-O bonds on the powder could not be unambiguously confirmed, since the characteristic wavelengths for these bonds are in the region of very strong Al-N stretching frequencies.
TL;DR: It was determined that apparently successfully optimized plans with a noisy dose calculation, which satisfied the required uniformity of the dose within the tumour, showed as much as 7% underdose when recalculated with a noise-free dose calculation.
Abstract: The effect of the statistical uncertainty, or noise, in inverse treatment planning for intensity modulated radiotherapy (IMRT) based on Monte Carlo dose calculation was studied. Sets of Monte Carlo beamlets were calculated to give uncertainties at Dmax ranging from 0.2% to 4% for a lung tumour plan. The weights of these beamlets were optimized using a previously described procedure based on a simulated annealing optimization algorithm. Several different objective functions were used. It was determined that the use of Monte Carlo dose calculation in inverse treatment planning introduces two errors in the calculated plan. In addition to the statistical error due to the statistical uncertainty of the Monte Carlo calculation, a noise convergence error also appears. For the statistical error it was determined that apparently successfully optimized plans with a noisy dose calculation (3% 1σ at Dmax ), which satisfied the required uniformity of the dose within the tumour, showed as much as 7% underdose when recalculated with a noise-free dose calculation. The statistical error is larger towards the tumour and is only weakly dependent on the choice of objective function. The noise convergence error appears because the optimum weights are determined using a noisy calculation, which is different from the optimum weights determined for a noise-free calculation. Unlike the statistical error, the noise convergence error is generally larger outside the tumour, is case dependent and strongly depends on the required objectives.