Showing papers by "Jožef Stefan Institute published in 1990"

Determination of cathepsins B and H in sera and synovial fluids of patients with different joint diseases.

Abstract: Synovial fluids and sera of patients with inflammatory and metabolic joint diseases contain different cysteine proteinases. The quantities of cathepsins B and H were determined by newly developed specific enzyme-linked immunoassay tests (ELISA), with detection limits of 0.5 microgram/l for cathepsin B and 3 micrograms/l for cathepsin H. The values of cathepsin B in normal sera ranged from 0.6 microgram/l to 2 micrograms/l, whereas in sera of patients with joint diseases they ranged from 1.7 micrograms/l to 18 micrograms/l. Cathepsin H was not found in sera (values below 3 micrograms/l), but was measurable in patients' synovial fluids. Patients with rheumatoid arthritis have on average the highest values of cathepsin B in synovial fluids, whereas patients with undifferentiated arthritis have the highest values of cathepsin H. The results show that cathepsins B and H are present in arthritic synovial fluids, where they may be implicated in destructive processes. There is yet no clear correlation between the quantity of each cathepsin released in synovia and the clinical diagnosis or the stage of the disease.

Einkristalluntersuchungen an AgF2

Abstract: Erstmals wurden schwarze, metallisch glanzende Einkristalle von AgF2 durch Erhitzen des mikrokristallinen AgF2 dargestellt (Monel-Autoklaven, T ≈ 400°C, HF/F2-Gemisch, 4 d). Die rontgenographische Untersuchung (a = 556,8(1); = 583,1(1); c = 510,1(1) pm; Z = 4; Parameter siehe Text) bestatigt die aus Neutronenbeugungsuntersuchung ermittelte Raumgruppe Pbca – D (Nr. 61) und ergibt Lageparameter, die mit den damals ermittelten Werten praktisch ubereinstimmen. Der Madelunganteil der Gitterenergie, MAPLE, sowie Effektive Koordinationszahlen, ECoN, werden uber Mittlere Fiktive Ionenradien, MEFIR, berechnet und diskutiert. Single Crystal Investigation on AgF2 For the first time single crystals of AgF2 (black, metalic bright) have been obtained by heating AgF2 powder under a mixture of HF and F2 in autoclaves at 400°C. It crystallizes orthorhombic in the space group Pbca – D (Nr. 61) – with a = 556.8(1), b = 583.1(1) and c = 510.1(1) pm; Z = 4. The Madelung Part of Lattice Energy, MAPLE, and the Effective Coordination Number, ECoN, via the Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.

Mills-nixon effect in benzocyclobutenes

Abstract: The structural features of benzocyclobutenes were studied using several semiempirical and ab initio techniques. Qualitative hybridization arguments and actual 6–31 G Hartree-Fock calculations show conclusively that benzocyclobutenes exhibit a typical Mills-Nixon effect which is most pronounced in benzo[1,2:3,4:5,6]tricyclobutene. It is concluded that the experimental X-ray structure of the perfluoro derivative of the latter compound is seriously in error.

Determination of trace elements in standard reference materials by the ko-standardization method.

Abstract: The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard reference materials SRM 1571 Orchard Leaves, SRM 1572 Citrus Leaves, and SRM 1573 Tomato Leaves showed the systematic error of 12 certified elements determined to be less than 8%. Thirty-four elements were determined in NIST proposed SRM 1515 Apple Leaves.

Initial Specific Surface Area and Graln Growth in Donor‐Doped Barium Titanate

Abstract: The grain growth of donor-doped BaTiO3 prepared from BaTiO3 powders with different initial specific surface areas was studied. Results show that a higher initial surface area and, consequently, a smaller critical grain size at the phase boundary drastically increase the critical amount of donor dopant, causing the grain size anomaly during sintering.

Mutations in the QVVAG region of the cysteine proteinase inhibitor stefin B.

Abstract: Variants of human stefin B were constructed by cassette mutagenesis. Val47 as the constituent of highly conserved QVVAG sequence was substituted by hydrophobic amino acids of increasing size - Ala, Ile and Phe. Recombinant proteins were expressed in E. coli and Ki values for papain were determined. Substitutions did not cause a major change in Ki value and we conclude that the interaction with the proteinases is not the reason for the conservation of the pentapeptide.

Vanadium determination at the ultra-trace level in biological reference materials and serum by radiochemical neutron activation analysis.

Abstract: In order to help resolve present inconsistencies of two orders of magnitude or more in reported levels of vanadium in human serum and blood, a totally postirradiation radiochemical neutron activation analysis (NAA) method was further developed and applied to some pertinent nanogram and subnanogram reference materials. In particular, the second generation human serum reference material of Versieck was found to contain a value of 0.67 +/- 0.05 ng/g dry wt., corresponding to 0.061 +/- 0.005 /4/ ng/mL original fresh serum. Results are also reported for some other appropriate CRMs. Additionally, a small-scale study in 10 normal subjects (5 m, 5 f) revealed levels similar to those in the serum reference material and in agreement with the lowest data reported in the literature. Discussion of pitfalls of vanadium determination and the use of reference materials is included.

Learning from examples—a uniform view

Abstract: We compare different empirical learning methods regarding their strategy of reduction of the subset with important examples in a measurement space. In this way a uniform view of AI and statistical methods alike is presented. Theoretically they are all based on the Bayes' classifier. They all construct a classification rule which partitions measurement space into target sets. Advantages and drawbacks of different methods are highlightened by simple examples. Error analyses enable deeper understanding of the learning and classification process in real world domains, characterized by incomplete and noisy data. Good error estimate is based on the balance between bias and variance. A deviation of the Laplacean error estimate is presented. We presented new mechanisms that use redundant knowledge in the explicit form. One of such systems, GINESYS (Generic INductive Expert SYstem Shell) is shortly presented. Heuristic reasoning and empirical results indicate that a proper use of redundant knowledge significantly increases classification accuracy. Over 10 basic AI and statistical systems were tested on two oncological domains. Results show that older AI methods provide usable information regarding the structure of data, but, on the other hand, their classification accuracy is often lower than that of the statistical methods. Standard statistical systems often achieve good classification accuracy, but are more or less non-transparent to users. Some new AI systems construct robust redundant knowledge, provide explanations in a humanly understandable way and outperform the classification accuracy of standard statistical methods.

Energy storage and heat deposition in flashlamp-pumped sensitized erbium glass lasers

Abstract: Measurements of population inversion energy storage and heat deposition in flashlamp-pumped Nd:Yb:Er:glass and Cr:Nd:Yb:Er:glass lasers are reported. A thermal camera is used to measure temperature changes following isolated flashlamp pulses. A rate equation model is developed in order to determine energy storage from the output versus input energy characteristics of erbium lasers operating in a free-oscillation mode. Contributions of different sensitizers are distinguished by spectrally filtering flashlamp-pump radiation. Ratios of the deposited heat per unit stored energy in both glasses are compared for several spectral regions. >

Random fields and quantum effects in proton glasses

Abstract: The effects of quantum fluctuations on the proton glass phase in mixed hydrogen-bonded ferro-antiferroelectric systems are considered. The system is described in terms of the infinite-ranged Ising pseudospin glass model in a transverse tunneling field in the presence of random parallel fields. The stability limit of the high-temperature proton glass phase is determined within the thermofield dynamic approach, and the behavior or linear and nonlinear susceptibility is evaluated.

K-shell ionization cross sections for Si, P, K, Ca, Zn, and Ga by protons and carbon ions in the energy range 1-6.4 MeV.

Abstract: Absolute {ital K}-shell ionization cross sections have been measured for thin targets of Si, P, S, K, Ca, Zn, and Ga using carbon ions between 1.0 and 6.4 MeV and protons of 1 and 2 MeV. The dependence of x-ray production cross sections on target thickness was determined. The experimental results are compared to the semiclassical approximation (Laegsgaard, Andersen, and Lund in 3 Proceedings of the Tenth International Conference on the Physics of Electron and Atomic Collisions, Paris, 1977, edited by G. Watel (North-Holland, Amsterdam 1977)), to the theory for direct Coulomb ionization of the 1{ital s}{sigma} molecular orbital (Montenegro and Sigaud, J. Phys. B. 18, 299 (1985)), to the perturbed stationary-state approximation with energy-loss, Coulomb, and relativistic corrections (ECPSSR) (Brandt and Lapicki, Phys. Rev. A 23, 1717 (1981)), and to the modification of the ECPSSR approximation (MECPSSR) (Benka, Geretschlaeger, and Paul, J. Phys. (Paris) Suppl. 12, C9-251 (1987)). The results for carbon ions are also compared to the statistical molecular orbital theory of inner-shell ionization for symmetric or nearly symmetric atomic collisions (Mittelman and Wilets, Phys. Rev. 154, 12 (1967)).

Sequence of the cDNA coding for ammodytoxin B

Abstract: Presynaptically toxic ammodytoxins belong to phospholipases of the group II (1). The most toxic isoenzyme ammodytoxin A (2) is one of the most toxic single chain phospholipases A2. About one order of magnitude more toxic are only complex presynaptically active phospholipases A2 (3). Ammodytoxin B is the least toxic isoenzyme from the Vipera ammodytes venom (4). It differs from ammodytoxin A in 3 and from intermediately toxic ammodytoxin C (5) in 5 amino acid residues. Here we report the sequence of a full-length cDNA found in the same library as that of ammodytoxin C (6). The two sequences are homologous and highly similar. Within the coding region there are 5 point mutations resulting in exchanged amino acids in mature protein and 2 silent mutations. One additional mutation is also found in the non-coding region on the 5' side. The 16 residues long signal peptide and the signal for polyadenylation are underlined. Amino acid numbering starts with the first amino acid of the mature protein. ACKNOWLEDGEMENTS