Showing papers by "University of Erlangen-Nuremberg published in 1989"

Antibacterial and Antifungal Properties of Essential Oil Components

Abstract: The solubility in water of essential oil constituents is directly related to their ability to penetrate the cell walls of a bacterium or fungus. The antimicrobial activity of essential oils is due ...

Transformation to continuous growth of primary human T lymphocytes by human T-cell leukemia virus type I X-region genes transduced by a herpesvirus saimiri vector

Abstract: The role of the X region of the genome of the human T-cell leukemia virus type I (HTLV-I) in the immortalization of lymphocytes has been difficult to distinguish from its role in viral replication as this region encodes at least two genes, tax and rex, required for replication and the expression of viral proteins. To determine whether the X region does encode immortalizing functions, a fragment of the HTLV-I provirus capable of expressing known X-region proteins was inserted into the genome of a transformation-defective, replication-competent Herpesvirus saimiri. Infection of fresh mitogen-activated human cord blood and thymocytes yielded immortal T-cell lines that had the same phenotype (CD4+, CD5+, HLA class II+, interleukin 2 receptor alpha-chain +) as lymphocytes transformed by cocultivation with HTLV-I. These experiments demonstrate that the X region encodes the functions of HTLV-I that immortalize a distinct subpopulation of human T cells. The experiments also demonstrate the utility of the H. saimiri vector for the transduction of heterologous genes into human T cells.

Low‐Temperature Surface Passivation of Silicon for Solar Cells

Abstract: Low-temperature-deposited silicon nitride and aluminum oxide films are investigated for reducing carrier recombination at the silicon surface. The insulator/silicon interface properties (fixed charge density, fast interface state density, and surface recombination velocity) are studied as a function of deposition and annealing temperature in the range of 270/sup 0/ - 550/sup 0/C. The effects of UV irradiation and their elimination by charge-induced passivation are extensively discussed. The successful application of both films for front surface passivation of a novel thin-silicon solar cell of the back collection type (BACK-MIS cell) is demonstrated. Finally, a simple configuration for efficient back surface passivation of solar cells is introduced as a possible substitute for the conventional back surface field.

Is there directional smelling

Abstract: The aim of the present study was to establish the crucial precondition for directional smelling, i.e. the ability of humans to discriminate between odorous stimuli perceived either from the right or from the left side. When the ‘pure’ odorants hydrogen sulphide or vanillin were used as stimulants localization was random. On the other hand stimulation with carbon dioxide or menthol yielded identification rates of more than 96%. These results established the fact that directional orientation, considering single momentary odorous sensations, can only be assumed, when the olfactory stimulants simultaneously excite the trigeminal somatosensory system.

Ferroelectric relaxation of the SrTiO3(100) surface.

Abstract: The surface structure of ${\mathrm{SrTiO}}_{3}$(100) was analyzed at T=120 K by means of low-energy-electron diffraction. The best theory-experiment fit results for a surface containing domains of two different layer terminations. Both of them show a first-layer puckering with oxygen ions being pulled out of the surface by s(Ti)=0.08 A\r{} and s(Sr)=0.16 A\r{} combined with a relaxation of the first two layer distances. This proves the surface to be ferroelectric different from the bulk property in agreement with theoretical predictions.

Temperature-gradient gel electrophoresis of nucleic acids: analysis of conformational transitions, sequence variations, and protein-nucleic acid interactions.

Abstract: Temperature-gradient gel electrophoresis (TGGE) is applied to analyze conformational transitions and sequence variations of nucleic acids and protein-nucleic acid interactions. A linear and highly reproducible temperature-gradient is established perpendicular or parallel to the direction of the electrophoresis. The instrument consists of an electrically insulated metal plate, which is heated at one edge and cooled at the other edge by two thermostating baths and is used as an ancillary device for commercial horizontal gel electrophoresis instruments. Biopolymers are separated in TGGE according to size, shape and thermal stability of their conformational transitions. If the temperature-gradient is established perpendicular to the electrophoresis, monomolecular conformational transitions of nucleic acids show up as continuous transition curves; strand-separation leads to discontinuous transitions. In the studies on viroid RNA it was shown that natural circular viroid RNA undergoes one highly cooperative transition detected by TGGE as a drastic retardation in mobility. Oligomeric replication intermediates of viroids exhibit coexisting structures which could not be detected by any other technique. Double-stranded satellite RNA from cucumber mosaic virus is a mixture of sequence variants, all of which have the identical length of 335 nucleotides. In TGGE six different strains were resolved. Sequence variants of viroids were analyzed by hybridizing viroid RNA to (-)strand viroid RNA transcripts from viroid cDNA clones. Sequence variations lead to mismatches in the double strands and thereby to a shift of the transition curve to lower temperature. Mutations in plasmids, particularly in cloned inserts, were detected by mixing plasmids of two different clones, linearizing, denaturing, renaturing, and searching for shifts in the transition curves, which are generated by mismatch-formation during the renaturation of (+)- and (-)strands from different clones. Examples are given for different viroid clones and HIV-clones from one and the same patient. In another example, clones with point mutations from site-directed mutagenesis are analyzed and selected by TGGE. TGGE is also applied to study the effect of amino acid exchanges in the Tet repressor from E. coli on the thermal stability of the repressor and on the mode of binding of the repressor to the operator DNA. The results are discussed under the aspect that TGGE may be applied as routine analytical laboratory procedure.

Scaling laws for lens systems.

Abstract: Situations exist in the area of optical information processing where one may choose between either a single large lens or many small lenslets side by side. The choice will be influenced by many parameters, among others by the space-bandwidth product SW. The SW is an upper limit for the number of data channels which can be handled in parallel. Hence, we investigate the scaling behavior of the space-bandwidth product. Professional lens designers sometimes have viewpoints different from those of designers of systems for digital optics. That fact may justify this investigation, performed by a nonlens designer.

Beam Shaping with Optical Array Generators

Abstract: An array generator is an optical system that splits an incoming beam of light into an array of many ‘beamlets’. Such a multiple beam-splitting system is necessary in optical data processing, where two-dimensional arrays of optical modulators, optical logic devices or optically bistable devices have to be read out optically or have to be provided with power-supply or bias beams. Other applications include multiple imaging and space-variant processing. The number of beams within an array has to be adapted to the size of the array of optical devices, also the modal shape of each single beam has to be adapted to the acceptable modes for the individual devices. Different systems for array generation are classified and compared with respect to their relevant parameters. Methods for modal adaptation are described. The influence of coherent noise and of chromatic errors is investigated. Non-Cartesian and irregular array generators are proposed.

Plasticity-induced martensitic transformation during cyclic deformation of AISI 304L stainless steel

Abstract: Specimens of AISI 304L stainless steel were deformed cyclically at room temperature at various plastic strain amplitudes Δϵpl/2. In addition to tests at constant plastic strain amplitudes, incremental step tests were also carried out. The cyclic deformation behaviour was investigated and related to microstructural changes observed by transmission electron microscopy (TEM). At low values of the plastic strain amplitude a saturation state was reached, whereas specimens fatigued at plastic strain amplitudes Δϵpl/2 > 0.3% exhibited, after initial cyclic hardening, an extensive secondary hardening stage which persisted until fracture. The reasons for this behaviour were clarified by TEM observations. Planar dislocation arrays with faults were observed after cycling at Δϵpl/2 = 0.02%. However, martensitic phases were not found. The specimens fatigued at Δϵpl/2 = 0.5% or in the incremental step test (0.02%<Δϵpl2<0.5%) displayed cell structures with a considerably higher number of stacking faults. Moreover, deformation-induced martensitic phases were observed and identified as ϵ- and α′-martensite by electron diffraction pattern analysis.

Evaluation and relevance of atopic basic and minor features in patients with atopic dermatitis and in the general population.

Abstract: In a prospective computerized study on atopic dermatitis (AD) several basic and minor clinical features in patients with AD (n = 110) and a sample of the normal population (n = 527) was studied systematically and analysed statistically with regard to their diagnostic importance. On basis of chi-square values a diagnostic score system was constructed which might help to establish a firm diagnosis of AD in patients with ambiguous cutaneous inflammatory disease. Based on this score system patients with more than 10 points should be considered atopic, patients with 6 to 10 points are suspected to be atopics. An association between serum IgE and the amount of atopic points was found. Seven percent of the normal population sample proved to be obviously atopic, another 19% were suspected to be atopics.

Quantitative Determination of Allicin and Alliin from Garlic by HPLC

Abstract: The procedure for allicin synthesis could be improved. The time for HPLC analysis of allicin was shortened by the application of different isocratic elution systems. Calibration was performed by use of an allicin/silica gel adsorbate as external standard and its allicin content could be confirmed by different methods. L-(+)-Alliin was synthesized and applied as external standard for the quantitative determination of alliin by HPLC. Diastereoisomers had been separated by repeated recrystallization. Fresh Allium sativum bulbs from different origins were analyzed with respect to allicin content after complete enzymatic conversion of alliin; allicin contents found were in the range of 0.4%. The corresponding alliin contents were in the range of 0.9%. For a comparative evaluation of the alliin- and the allicin-HPLC determination methods, commercially available garlic preparations were analyzed, demonstrating that both methods are appropriate. However, the application of the HPLC system for allicin determination, in addition to providing information on the alliin-dependent allicin-generating capacity, enables the simultaneous quantification of allicin transformation products, such as ajoenes, dithiins, and alkyl sulfides. It was found that, for quantitative GLC analysis of allicin, allicin has to be used as an external standard.

Identification of a neutralizing epitope on glycoprotein gp58 of human cytomegalovirus.

Abstract: Human cytomegalovirus contains an envelope glycoprotein of 58 kilodaltons (gp58). The protein, which is derived from a glycosylated precursor molecule of 160 kilodaltons via proteolytic cleavage, is capable of inducing neutralizing antibodies. We have mapped the epitopes recognized by the neutralizing monoclonal antibody 7-17 and a second antibody (27-287) which is not neutralizing. Overlapping fragments of the carboxy-terminal part of the open reading frame coding for gp58 were expressed in Escherichia coli as beta-galactosidase fusion proteins. The reactivities of antibodies 7-17 and 27-287 were determined by Western blot (immunoblot) analysis. Both antibodies recognized sequences between amino acids 608 and 625 of the primary gp58 translation product. The antibodies almost completely inhibited one another in a competitive binding assay with intact virus as antigen. Moreover, antibody 27-287 was able to inhibit the complement-independent neutralizing activity of antibody 7-17.

Number and size of lymph nodes and node metastases in rectal carcinomas

Abstract: Assessment of lymphatic spread is an important factor in staging rectal cancer. Knowledge of the presumed number and size of metastases present is essential before assessment of the accuracy of preoperative visualization of node metastases can be undertaken. We examined the lymph nodes of 196 patients with rectal carcinoma. Among 4985 lymph nodes, 586 metastases were found. Ninety-eight patients had metastases in pararectal nodes and in nodes along the superior rectal artery. These nodes are potentially visible by ultrasound. In 31 of these patients (32%), all metastases were 5 mm or less and in 8 cases (8%) 2 mm or less. These small nodes are difficult to see on ultrasound. We also found significant relationships between depth of invasion, grade of differentiation and lymphatic spread. These data suggest that a careful histological search for small metastases should be undertaken to avoid falsenegative lymph node findings.

Organic Dications: Gas Phase Experiments and Theory in Concert

Abstract: Knowledge of structure and bonding are integral parts in the understanding of the chemistry of neutral, radicaloid and positively or negatively charged species. The interplay of molecular bonding and the inherent electrostatic repulsion in doubly-charged molecules expands our insight in the versatility of bonding in electron deficient molecules. Small organic dications are now routinely detected in the gas phase by a variety of mass spectrometric techniques. Ab initio molecular orbital theory has advanced to the stage of accurately predicting potential energy surfaces. This review highlights the symbiotic relationship between gas-phase ion and computational studies and gives a rationale for the salient bonding features in doubly-charged organic cations.

Prognostic factors in rectal carcinoma. A contribution to the further development of tumor classification

Abstract: In 597 patients with adenocarcinoma or mucinous adenocarcinoma of the rectum, the prognosis after radical resection for cure was investigated. Staging according to the fourth edition of the UICC TNM Classification showed a good correlation to prognosis. By multivariate analysis, various additional independent prognostic factors could be demonstrated. The individual additional prognostic factors are partly of significance in some pTNM defined stages and substages, but not in others. In order to obtain the most detailed knowledge of prognostic factors after radical resection for cure, multivariate analysis of prognostic factors in colorectal carcinoma must be performed not only in separate colonic and rectal groups, but also separately for each of the individual pTNM defined stages and substages.

Origin, metabolism and function of extracellular adenine nucleotides in the blood

Abstract: In previous views the role of adenine nucleotides was thought to be confined to the intracellular space of the cell. However, research of the last decades has revealed that nucleotides also occur in the extracellular space. This survey deals with the sources, metabolism and the role in blood of the extracellular adenine mononucleotides ATP, ADP, AMP and the dinucleotides diadenosine tetraphosphate (Ap4A) and diadenosine triphosphate (Ap3A). The latter two are novel compounds, which have recently been discovered in human platelets. The mononucleotides originate from damaged tissues, from red blood cells during haemolysis, from activated platelets, the working muscle and from the nervous system, wherease the dinucleotides are exclusively released from stimulated platelets. Both the adenine mono- and the dinucleotides act as signal molecules on blood cells as well as on cells of the vascular wall, thereby modulating physiological processes such as platelet aggregation, histamine release from mast cells, regulation of vascular tone and white cell functions. In order to limit the signal effects of extracellular nucleotides, blood cells, plasma and the interior of the vessel walls are provided with nucleotide splitting enzymes: ATP, ADP and AMP are mainly degraded by ectoenzymes present on blood cells, endothelial and on smooth muscle cells, whereas dinucleotides are primarily metabolized by plasma enzymes. This review closes with the presentation of the clinical utility of Ap3A and Ap4A as tools for the diagnosis of platelet storage pool defects.

Digital Optical Computing With Symbolic Substitution

Abstract: Symbolic substitution is a spatial logic which is adapted well to optical processing. Unlike Boolean logic it also includes spatial information in the coding. It requires only regular interconnections and nonlinear devices with limited fan-out. Nevertheless the potential of this kind of logic ranges from parallel binary arithmetic to a programmable MIMD processor. Fundamentals of symbolic substitution and its applications are presented.

Neurophysiologic monitoring in posterior fossa surgery. II. BAEP-waves I and V and preservation of hearing.

Abstract: Of 135 cases operated upon for posterior fossa lesions 103 showed preoperative hearing. In 34 acoustic neurinomas 14 had postoperative initially preserved hearing, in 20 microvascular decompressions 19 had preserved postoperative hearing and in 49 other lesions 5 lost hearing. The relationship between preservation of hearing and the preservation or loss of brainstem auditory evoked potentials (BAEP) waves I and V in the three groups of namely: acoustic neurinomas, microvascular decompressions and other lesions are presented. It is noteworthy that only patients with preserved waves I or V are suitable candidates for intraoperative monitoring. The loss of wave V is usally associated with hearing loss (10 out of 13 cases). But hearing loss is also possible despite preservation of wave I (3 out of 60) or despite preservation of wave V (2 out of 68). The predictive value of the preservation of waves I and V is not an absolute one, but it strongly suggests preserved hearing postoperatively. The dilemma remains that once waves I or V are lost during surgery there is no certainty as to postoperative hearing. If wave V recovers after an initial loss, hearing is usually preserved but not in all cases. In wave I amplitude changes alone were more frequent than in wave V, where latency changes alone were more frequently observed. Particular surgical manoeuvres could be found to be often associated with a wave deterioration. Hearing preservation could never be achieved in patients who already preoperatively had no BAEP. It is concluded that BAEP monitoring is of great value in surgery for microvascular decompression and cerebello-pontine-angle (CPA) tumours with preserved hearing.

Identification of the major capsid protein gene of human cytomegalovirus.

Abstract: The coding region for the major capsid protein (MCP) of human cytomegalovirus (HCMV) was identified by comparing the protein sequence with the respective sequences of herpes simplex virus (HSV), Epstein-Barr virus, and varicella-zoster virus. The predicted length of the HCMV MCP was 1,370 amino acids. Comparison of the MCP sequences of the different human herpesviruses showed a homology of 25% to the MCP of HSV type 1, a homology of 29% to the MCP of Epstein-Barr virus, and a homology of 23% to the MCP of varicella-zoster virus. A subfragment of the HSV type 1 KpnI i fragment encoding the MCP VP5 cross-hybridized with the HCMV HindIII U fragment containing part of the MCP gene. Northern (RNA) blot analyses with subclones out of the coding region for the HCMV MCP detected one large transcript of about 8 kilobases. A portion of the open reading frame was expressed in Escherichia coli plasmid pBD2 IC2OH as a beta-galactosidase fusion protein and was used to generate polyclonal antibodies in New Zealand White rabbits. The obtained antisera reacted in Western immunoblots with the MCP of purified HCMV virions. A monoclonal antibody against the human MCP and a monospecific rabbit antiserum against strain Colburn of simian cytomegalovirus detected the fusion protein as well as the MCP of purified virions in immunoblots.

Sweet's syndrome: clinical spectrum and associated conditions

Abstract: We report six cases of acute neutrophilic dermatosis (Sweet's syndrome). Clinical and laboratory data as well as the results of further examination of the patients are presented. Unusually associated disorders, such as Crohn's disease together with an erythema nodosum or adenocarcinoma of the colon, were diagnosed in these patients.

Identification and sequence analysis of the Bacillus subtilis W23 xylR gene and xyl operator.

Abstract: The xyl operator of Bacillus subtilis W23 was identified by deletion analysis of the xyl regulatory region as a 25-base-pair (bp) sequence located 10 bp downstream from the xyl promoter The outer 10 bp of the xyl operator exhibit perfect palindromic symmetry, while 5 central bp are nonpalindromic It was demonstrated that the penultimate base pair near the end of this sequence is important for repressor binding The location of the xylR gene encoding the repressor was determined by its ability to mediate xylose-dependent repression of a xyl-cat fusion on a multicopy plasmid The nucleotide sequence of 1,355 bp from this DNA was analyzed and contains an open reading frame with a coding capacity for 384 amino acids leading to a protein with a calculated molecular weight of 42,270 A mutant with a deletion in this reading frame showed no repression of the xyl-cat fusion The coding sequence is preceded by a suitable ribosome-binding sequence and uses GTG as a start codon and TAA as a stop codon The relationship of these results to corresponding data obtained from B subtilis 168 is discussed