Showing papers by "University of Jena published in 1992"

Quantitative correlation between the residual activity of beta-hexosaminidase A and arylsulfatase A and the severity of the resulting lysosomal storage disease.

Abstract: A previously suggested model for the correlation between residual activity of a lysosomal enzyme and the turnover rate of its substrate(s) has been extended to a discussion of substrate accumulation rates in individual cells and whole organs. With these considerations, much of the observed variability in age of onset and clinical phenotype, as well as the phenomenon of pseudodeficiency, can be understood as the consequences of small differences in the residual activity of the affected enzyme. In order to experimentally verify the basic assumptions on which this model rests, studies were performed in cell culture. The radiolabeled substrates ganglioside GM2 and sulfatide were added to cultures of skin fibroblasts with different activities of β-hexosaminidase A or arylsulfatase A, respectively, and their uptake and turnover measured. In both series of experiments, the correlation between residual enzyme activity and the turnover rate of the substrate was essentially as predicted: degradation increased steeply with residual activity, to reach the control level at a residual activity of approximately 10–15% of normal. All cells with an activity above this critical threshold had a normal turnover. Comparison of the results of these feeding studies with the clinical status of the donor of each cell line basically confirmed our notions but also revealed the limitations of the cell culture approach.

Polaron-pair generation in poly(phenylene vinylenes).

Abstract: The effects of weak magnetic fields on the photoconductivity of poly(p-phenylene vinylene) (PPV) and two derivatives, poly(1,4-phenylene-1,2-dimethoxyphenyl vinylene) (DMOP-PPV) and poly(2-phenyl-1,4-phenylene vinylene) (PPPV), were observed within the temperature range 130\char21{}350 K. These effects are attributed to the formation of interchain pairs involving a negative polaron and a positive polaron. A polaron pair is formed as a result of interchain electron transfer from a molecular exciton. The lifetime of a pair is estimated to be within the range of ${10}^{\mathrm{\ensuremath{-}}8\char21{}}$${10}^{\mathrm{\ensuremath{-}}9}$ s. Thermal dissociation of a polaron pair produces free charge carriers, and recombination of the pair regenerates a singlet or triplet exciton on a single conjugated segment of a chain.

Glass formation, properties and structure of glasses in the TeO2ZnO system

Abstract: Glass formation occurs in the zinc tellurite system in the region of the eutectic (21 mol% ZnO) on the TeO2-rich side of the phase diagram. Glasses are characterized by a high refractive index which increases with TeO2 content. The glasses are transmitting from about 400 nm to about 6 μm with OH absorption bands at 3.3 and 4.4 μm. Short range order of the glasses was deduced with neutron diffraction, infrared and Raman spectroscopy by comparison with the spectra of the synthesized crystalline α-TeO2, Zn2Te3O8 and ZnTeO3. Glasses consist of disordered TeO4, TeO4, TeO3+ and TeO3 building units. The number of the TeO3+1 units is limited by ZnO addition. There is a relatively strong structural correlation between the glasses and the crystalline compound Zn2Te3O8 in accord with the phase diagram.

Cation valencies and distribution in the spinels NiMn2O4 and MzNiMn2-zO4 (M = Li, Cu) studied by XPS

Abstract: Photoelectron spectroscopic investigations (XPS) of the spinels NiMn2O4 and MzNiMn2−zO4 (M = Li, Cu) in comparison with Mn2TiO4, ZnMn2O4, and MgNiMnO4, containing Mn in only one oxidation state, show that in the former compounds MnII, MnIII, and MnIV are present. By a fitting process yielding the amounts of the Mn ions in the different oxidation states it is possible to determine the cation distribution of NiMn2O4 which is characterized by a high inversion parameter and a considerable degree of disproportionation. Cation valencies and their distribution in the substituted spinels are discussed. An increasing concentration of MnIV with higher values of z is reflected in the spectra by shift of the Mn p signals and by changes in their shape.

Octopamine immunoreactive cell populations in the locust thoracic‐abdominal nervous system

Abstract: We describe octopamine-immunoreactive somata and their projections in the pro- meso-, meta- and pregenital abdominal-ganglia of locusts. Immunoreactive midline somata were identified as dorsal- and ventral- unpaired median (DUM- and VUM-, respectively) neurones due to their: characteristic large size and positions of somata, primary neurites in DUM-tracts giving rise to T-junctions, and bilaterally projecting axons. In the prothoracic ganglion there are most likely 8 such cells; in the meso- and metathoracic, some 20 each; and in each individual pregenital abdominal ganglion, typically 3. All appear to project to peripheral nerves and their numbers correspond to the number of peripherally projecting DUM-cells identified to date in each ganglion. We suggest that probably all peripherally projecting DUM-cells are octopaminergic in the examined ganglia. Presumptive DUM-interneurones are not octopamine-immunoreactive, but, confirming other studies, are shown to label with an antiserum to gamma-amino butyric acid (GABA). Other octopamine-immunoreactive neurones include a pair of midline, prothoracic, anterior medial cells, not necessarily DUM-cells, and a pair of ventral lateral somata in each thoracic- and the first abdominal ganglion. The latter project intersegmentally in ventral tracts. Intersegmentally projecting octopamine-immunoreactive fibers in dorsal tracts probably arise from a prothoracic DUM-cell, which leaves through suboesophageal nerves, or descending suboesophageal DUM-cells. Thus, the octopamine-immunoreactive system of thoracic and pregenital abdominal ganglia in locust comprises all peripherally projecting DUM-cells and a plurisegmental network.

Quantitative study of articular cartilage and subchondral bone remodeling in the knee joint of dogs after strenuous running training.

Abstract: All tissues of the joint are affected in some way in osteoarthritis because the joint is an interactively functioning unit. Our goal was to investigate the combined responses of articular cartilage and subchondral bone to altered loading conditions to improve our understanding of the physiology of these two components and, ultimately, the pathophysiology of osteoarthritis. A group of 20 female beagle dogs were divided pairwise into runners (n = 10) and controls (n = 10). The running training on a treadmill started at the age of 15 weeks, and during the following 40 weeks the running distance was gradually increased to 40 km/day with a 15 degree uphill inclination. With this daily running distance the beagles ran another 15 weeks. The samples for histology were taken from 11 different locations of the knee joint. Subchondral bone and articular cartilage histomorphometry was carried out in three different regions of the specimens (central, middle, and peripheral regions) using an image-analyzing system and an eyepiece graticule. In all regions of the articular cartilage, both the uncalcified and calcified cartilage showed slightly increased thickness in the runner dogs. The change was more evident in the peripheral and the central areas. The thickness of the subchondral bone plate tended to be higher in runners, too. Bone histomorphometric parameters showed significant signs of increased remodeling. The most notable change was the enlargement of the bone formation surface. The most intense remodeling was usually observed either centrally or peripherally in the articular surface. The strongest increase in trabecular bone volume and thickness of the cartilage was recorded in the femoropatellar area.(ABSTRACT TRUNCATED AT 250 WORDS)

Light scattering from the volume of optical thin films: theory and experiment

Abstract: A theoretical model is presented that describes the volume scattering in thin optical films, particularly in typical columnar structures. It is based on a first-order perturbation theory that concerns the fluctuation of the dielectric permittivity in the film. For evaporated PbF(2) films that show a pronounced columnar morphology, angular as well as total integrated scattering measurements at lambda = 633 nm have been performed on a special layer design to suppress roughness-induced scattering. A comparison of the predicted theoretical and the measured experimental values leads to such structural parameters as packing density and the evolutionary exponent of the columns.

31P NMR investigations of binary alkaline earth phosphate glasses of ultra phosphate composition

Abstract: 31P NMR CW and FT MAS measurements have been used to investigate the structural composition of x(MeO)·(1−x)(P2O5) glasses (Me = Ca, Sr, Ba, x = 0.25−0.50). The influence of the structural composition on components of the chemical shift tensors is determined and discussed by means of a correlation between isotropic chemical shifts in crystalline phosphates and molecular structure published recently by Sternberg et al. [Z. Phys. Chem. Neue Folge 168 (1990) 115].

Conductivity data and preparation routes for NiMn2O4 thermistor ceramics

Abstract: Requirements for the formation of NiMn2O4 thermistor ceramics with highly reproducible electrical parameters are reported. The application of the defect spinel powder NiMn2□3°/4O4 + δ prepared by low temperature decomposition of (Ni, Mn)-oxalate mixed crystals together with a small addition of Pb5Ge3O11 as sintering aid is shown to be most advantageous. Thus single-phase NiMn2O4 ceramics of sufficient density are obtained on sintering at 1000°C (40h, O2 atmosphere) and annealing at 800°C (40h) for reoxidation. The electrical conductivity of NiMn2O4 is found to be σ20 C = 5·0 ± 0·2 × 10−4Ω−1cm−1. The activation term, B = 3775 ± 7 K is deduced from simple Arrhenius analysis in the range 273 < T < 343 K allowing possible exchange of thermistors with an accuracy ΔT ≤ ± 0·1 K. A more accurate linearization of the experimental data succeeds from the equation σ(T)=σ(T1)(T1/T)k exp[−Bk(1/T−1/T1)] with k = 2·91 ± 0·05, yielding Bk = 2853 ± 15 K = 0·246 ± 0·001 eV as the activation energy representative for NiMn2O4. Ageing behaviour and the influence of decomposition in air with rising temperature on the electrical properties are studied.

Finding Hamiltonian paths in cocomparability graphs using the bump number algorithm

Abstract: Hamiltonian Path/Cycle are well known NP-complete problems on general graphs, but their complexity status for permutation graphs has been an open question in algorithmic graph theory for many years. In this paper, we prove that theHamiltonian Path problem is solvable in polynomial time even for the larger class of cocomparability graphs. Our result is based on a nice relationship between Hamiltonian paths and the bump number of partial orders. As another consequence we get a new interpretation of the bump number in terms of path partitions, leading to polynomial time solutions of theHamiltonian Path/Cycle Completion problems in cocomparability graphs.

Determination of the substitution patterns of cellulose methyl ethers by HPLC and GLC- comparison of methods

Abstract: The substitution patterns of methyl cellulose as well as of a thexyldimethylsilyl cellulose after permethylation were determined by hydrolysis and separation of the resulting partially methylated glucoses without further derivatization by h.p.l.c.. On an amine-modified silica column the solutes get separated into glucose, 2,3,6-tri-O-methyl glucose and the groups of mono-O-methyl-and di-O-methyl glucoses. A chromatographic run on a reversed-phase column enables the identification of the single mono-O-methyl- and di-O-methyl glucoses. In this way, a determination of both the average degree of substitution and the substitution pattern of cellulose derivatives is possible. Comparison of the results with those obtained by standard methylation analysis including g.l.c.-m.s. proves the correctnes of the method employed.

Preferred size of peptides that bind to H-2 Kb is sequence dependent.

Abstract: The identification of naturally processed viral peptides reveals that major histocompatibility complex (MHC) class I epitopes are composed of nine or eight amino acid residues. Peptides eluted from H-2 Kb MHC class I molecules have been suggested, as a class, to be eight amino acid residues long. To assay for peptide-class I interactions, a stabilization assay described for surface labeled "empty" class I molecules was employed, but on biosynthetically labeled class I molecules. The Sendai virus nucleoprotein-derived octapeptide APGNYPAL does not bind and stabilize Kb molecules, whereas other octameric Kb-restricted peptides and the nonameric peptide FAPGNYPAL interact stably. We attribute the failure of Sendai octamer binding to the presence of proline in position two: replacement of proline renders the resulting octamers as efficient as FAPGNYPAL for binding and stabilization of H-2 Kb. Substitution of glycine in position three of APGNYPAL slightly improves its Kb stabilizing capacity. Iodination of the tyrosine residue significantly alters the binding properties of the nonamer peptide. We conclude that the length of epitopes as selected by the class I Kb molecule is influenced by their sequence and suggest that proper positioning of the NH2 terminus of peptides is essential for class I stabilizing properties. The ability to stabilize newly synthesized "empty" class I molecules with peptide argues against an involvement of beta 2 microglobulin exchange in the experiments described here.

Adherence to and cytotoxicity of Escherichia coli for eucaryotic cell lines quantified by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide).

Abstract: Adherence of Escherichia coli to human epithelial cells (HEp-2) was studied using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) which is cleaved by enzymes of eucaryotic or procaryotic cells to formazan. This method allows to quantify adherence of Escherichia coli to HEp-2 cells and offers the advantage of assaying a large number of eucaryotic cells without using specific antisera or radioactive material. Furthermore, toxic effects of isolated hemolysin cloned in Escherichia coli onto a renal tubular cell line (LLC-PK1) was investigated by this method, showing reduced cellular viability of tubular cells after an incubation period of 10 to 20 min. MTT is therefore considered to be useful to assay the adherence of Escherichia coli to eucaryotic cells and to quantify toxic effects in eucaryotic cells induced by bacterial virulence factors.

Absorption and fluorescence of pyrylium salts

Abstract: Absorption and fluorescence of donor-substituted pyrylium compounds are studied in order to get information of the x- and y-chromophore system and of the role of structural and solvent effects. The experimental results are in accordance with the assumption that the absorption and fluorescence behaviour can be rationalized in terms of intramolecular radiative and non-radiative charge transfer (charge shift) processes.

Ion implantation in III-V compounds

Abstract: Because of their specific physical properties A III B V compound semiconductors are widely used for the fabrication of special electronic and optoelectronic devices. For a planar technology ion implantation seems to be the most promising doping method for these materials because the conventional diffusion technology is complicated due to the thermal instability of the materials, and the fabrication of epitaxial layers with parameters required for these purposes is connected with high costs. Besides that ion implantation offers the advantages already known from the silicon technology. However, in the compound semiconductors the variety of possible native defects is higher than in the elementary semiconductors, and the influence of the implantation parameters on the kind and concentration of defects produced during ion implantation is much more pronounced in these materials compared to silicon. As a consequence the annealing of damage as well as the electrical activation of the dopants are more complex processes than in silicon, and the choice of the annealing parameters requires information about kind and concentration of defects produced in the materials. The present paper gives a brief review about damage production connected with ion implantation in GaAs, GaP, InP and InAs. The influence of ion mass, ion fluence, dose rate and implantation temperature on the remaining damage is discussed. Additionally, an overview of the use of different annealing methods (conventional, laser and rapid thermal annealing) for the electrical activation of dopants, especially in ion implanted GaAs layers, is given.

On a hierarchical basis multilevel method with nonconforming P1 elements

Abstract: We develop a hierarchical basis multilevel method for symmetric second order elliptic boundary value problems in two-dimensional polygonal domains based on nonconforming P1 triangular elements. The main result is that the condition number of the hierarchical discretization is bounded byO(k) wherek is the number of refinement levels. For comparison, Yserentant's result yields the sharp boundO(k 2) for the corresponding hierarchical discretization with conforming linear elements.

Radiation effects in glasses

Abstract: Glass was produced by man about 4000 years ago. The scientific exploration of glass is very young and closely connected with Jena. Fraunhofer, Goethe, DobEreiner, Abbe, Zeiss and Schott are famous names on this field. Both crystals and glasses are solids. However, there are fundamental differences in their properties and behavior. Glass is a thermodynamically unstable state and has a defect structure compared to the crystal. Glass and its properties arc subject to a variety of changes under the influence of high energy radiation. In general, effects extend from the reduction of specific ions to the collapse of the entire network. Ultraviolet and X-ray radiation effects on UV-transmitting glasses will be discussed.

Intra-individual variability of caffeine elimination in healthy subjects.

Abstract: Caffeine is a popular test substance for assessing the activity of hepatic drug metabolizing enzymes in vivo and in vitro. A correct estimation of the relative magnitudes of intra-individual and inter-individual variations in caffeine elimination is significant for the use of the elimination parameter of caffeine to characterize the biotransformation capacity of a specific form of cytochrome P-450 (1AII) in vivo. The purpose of this study is to demonstrate the magnitudes of fluctuation of caffeine-clearance and half-life as well as inter- and intra-individual comparison in 12 healthy male subjects. Compared to the high reproducibility of caffeine decay curves in each healthy male, caffeine elimination varied more extensively between subjects. The distribution of variance amounted to: intra-individual 21.4%, inter-individual 78.6%. The knowledge of variance provided precise evidence of the sample size, which is necessary to prove previously defined differences.

Readily hydrolyzable cellulose esters as intermediates for the regioselective derivatization of cellulose, 1. Synthesis and characterization of soluble, low-substituted cellulose formates

Abstract: A new procedure was developed for the synthesis of low-substituted, soluble cellulose formates. In a mixture containing cellulose, formic acid, phosphoric acid and water, cellulose can be dissolved within several hours, and after 24 h cellulose formates with a DS of about 0.6 that are soluble in DMSO could be obtained. By adding sulfuric acid as a dehydrating agent to the formylating system, formates with DS-values up to 1.2 that are soluble even in DMF and N,N-dimethylacetamide are formed after a very short reaction time of 15 min. 13C-NMR studies show a strongly preferred formylation of the primary hydroxy groups of cellulose. Furthermore, the extent of depolymerization during the formylation reaction was investigated for various cellulose materials. Niedrigsubstituierte, losliche Celluloseformiate konnen durch Veresterung von Cellulose in einem Gemisch aus Ameisensaure, Phosphorsaure und Wasser hergestellt werden. Die nach einer Reaktionszeit von 24 h erhaltenen, in DMSO loslichen Formiate weisen einen durchschnittlichen Substitutionsgrad (DS) von 0,6 auf. Der Zusatz von Schwefelsaure als dehydratisierendes Agens zum Formylierungsgemisch fuhrt bereits nach Reaktionszeiten von 15 min zu in DMF und N,N-Dimethylacetamid loslichen Celluloseformiaten mit DS-Werten bis 1,2. Mittels 13C-NMR-Spektroskopie konnte eine stark bevorzugte Formylierung der primaren Hydroxygruppen der Cellulose nachgewiesen werden. Desweiteren wurde das Ausmas der Depolymerisation wahrend der Veresterung fur unterschiedliche Cellulosematerialien untersucht.

Dry-etching processes for high-temperature superconductors

Abstract: Patterning of thin films and multilevel structures of high-temperature superconductors is a key technology for microelectronic applications. We performed a comparative study of Ion Beam Etching (IBE) and Reactive Ion Etching (RIE) processes for YBa 2 Cu 3 O 7−δ thin films. The RIE process with a pure chlorine plasma yielded small etching rates, caused by chemical modifications of the sample surface which result in a passivation layer reducing the chemical etching rate. Using IBE, microstructures down to the 1 μm regime could be fabricated without reducing the critical temperature T c and the critical current density J c of the material. Etching rates up to 40 nm/min could be achieved without deteriorating the properties of the superconducting film by cooling the sample effectively during the etching process. The influence of the etching process on J c was investigated by imaging the spatial distribution of the critical current along the patterned microstructures using Low-Temperature Scanning Electron Microscopy (LTSEM).

Transformation of Gibberella fujikuroi: effect of the Aspergillus nidulans AMA1 sequence on frequency and integration.

Abstract: A stable and reproducible transformation selection system for Gibberella fujikuroi protoplasts based on the Aspergillus nidulans arg B gene, encoding ornithine transcarbamylase, has been developed. Inclusion into the vector of the A. nidulans DNA fragment (AMA1), which permits plasmid autonomous replication in A. nidulans, A. niger and A. oryzae, appeared to permit autonomous replication of G. fujikuroi although the transformation frequency was increased by only two-fold. Transformation was also achieved using the bacterial hygromycin B resistance gene under the control of G. pulicaris and A. nidulans promoters.