Showing papers by "University of Erlangen-Nuremberg published in 1987"

Symbiodinium microadriaticum freudenthal, s. goreauii sp. nov., s. kawagutii sp. nov. and s. pilosum sp. nov.: gymnodinioid dinoflagellate symbionts of marine invertebrates

Abstract: The use of several independent biochemical, physiological, morphological, and behavioral assays has resulted in the reassessment of the taxonomy of the gymnodinioid symbionts of marine invertebrates which belong to the genus Symbiodinuim Freudenthal (Dinophyceae). The formal description of the type species S. microadriaticum Freudenthal is augmented, and three new species are introduced; S. goreauii, symbiotic with the Caribbean sea anemone Ragactis lucida; S. kawagutii, harbored by the Hawaiian stony coral Montipora verrucosa; and S. pilosum, inhabiting the Caribbean zoanthid Zoanthus sociatus.

Strategic Control: A New Perspective

Abstract: This paper proposes an alternative to the classical feedback model of control. It emphasizes uncertainty and complexity as basic elements in strategic management. Strategic control is conceptualized as a feedforward process compensating for the selectivity of planning. This idea forms the basis of a 3-step model of strategic control. Some implications for practice are discussed.

Sodium, Potassium, Rubidium, and Cesium: X-Ray Structurai Analysis of Their Organic Compounds1

Abstract: Publisher Summary This chapter discusses the published X-ray investigations of organometallic compounds of Na, K, Rb, and Cs. Organometallic molecules are defined as having metal–carbon contacts or closely related structures. The chapter presents structures from the Cambridge Crystallographic Data Base that might be termed to be “organometallic” in this restricted sense, although representative examples of related compounds are included. Systems that are organic but contain metal heteroatom rather than metal–carbon contacts are illustrated and many structures through 1985 also are reported. The enhanced reactivity of the organometallic compounds of the heavier alkali metals is a desirable asset but may also lead to ready thermal decomposition. Aggregation of organoalkali compounds is essentially electrostatic; two or more M–C bond dipoles interact mutually with one another. With notable exceptions, the structures of organoalkali compounds have not been determined on the pure compounds. The NiAs-like arrangements allow the anions to invert or, in the extreme, to become planar. Ail compounds of the alkynyl type possess layered or three-dimensional structures.

An evaluation of the performance of diffuse function‐augmented basis sets for second row elements, Na‐Cl

Abstract: The energetic effects of the addition of diffuse functions to molecules with second-row elements are much less dramatic than those for their first-row counterparts. Although diffuse functions on second-row elements have little effect on the geometries and vibrational frequencies of neutral molecules, significant changes are found for anions. While the largest basis set, 6-31 + G*, generally performs best, the results at 3-21 + G* are comparable, and this basis can be recommended for practical applications.

Human Papillomaviruses And Genital Cancer

Abstract: Publisher Summary Papillomaviruses are clearly proven to be the etiologic agents of anogenital lesions, with the potential to progress to squamous cell carcinomas. Viral particles, DNA, and/or capsid antigens can be demonstrated in benign precursors and the proliferations can be transmitted from person to person by cell-free extracts. The complete nucleotide sequences of Human Papillomaviruses (HPVs)—namely, HPV 6, HPV 11, and HPV 16—revealed the familiar genome organization of papillomaviruses and homologous sequences to those open reading frames that were shown to code for transforming functions in the case of BPV1. Malignant conversion of papillomavirus-induced tumors is well established for a number of animal systems and for the human disease epidennodysplasia verruciformis. HPV DNA persists in genital carcinomas either integrated into the host genome or extrachromosomally and is transcribed at least in some tumors. The worldwide prevalence of HPV 16 is noteworthy and may possibly indicate an increased cancerogenic potential of this virus. A tentative calculation indicates that the cancer risk after HPV infection equals or exceeds the risk attended with the infections by other human tumor viruses such as HTLVI, Epstein-Barr virus, or hepatitis B virus. Tumor progression is certainly subjected to additional factors such as chemical or physical carcinogens, hormones, and systemic or local immune deficiencies. The molecular biology of HPV infection has to be further examined to learn more about the viral role in keratinocyte transformation, which will be essential to define relevant diagnostic probes and possible candidates for therapeutic intervention.

Adaptive nonlinear filters for simultaneous removal of different kinds of noise in images

Abstract: A novel adaptive median filter is proposed. It allows the simultaneous removal of a combination of signal-dependent and additive random noise in addition to mixed impulse noise in images, processed in a single filtering pass. The adaptation algorithm is based on the local signal-to-noise ratio. An extension of the class of nonlinear mean filters to adaptive filters is considered. The performance of the adaptive median filter is compared to the commonly used median filter and the nonlinear mean filter.

Multivisceral resections in colorectal cancer.

Abstract: From 1969 to 1983 a total of 1918 patients with colorectal cancer were treated by curative resection. One hundred twenty one patients in this group had multivisceral organ involvement, necessitating extended multivisceral radical resection. Tumor infiltration was proven histologically in 55 percent, while 45 percent had inflammatory adherence to the attached organ only. Postoperative mortality was 12 percent. Dukes' A and B stages were present in 57 percent. The five-year survival rate (postoperative mortality included) was 54 percent for patients with inflammatory adherence, 49 percent for patients with tumor infiltration resecteden bloc without tumor tears or rupture, and 17 percent when the surgeon inadvertently had torn or cut into tumor tissue during resection.

Methods of measurement of thermal thresholds.

Abstract: Thermal tests were performed in 117 healthy subjects on the face, wrist and leg; 32 were tested on the legs with different rates of cooling and warning. Additionally 2 groups of diabetics (37 patients) were tested. Thermotesting was most sensitive on the legs using a rate of temperature change of 2.5 – 2.8 oC/s. Warm and cold perception should be tested separately. Cold perception testing is most sensitive. Combined tests of warm and cold thresholds as well as the testing of cool pain and heat pain do not improve results. Abnormal cold perception may be an early indicator of diabetic small fibre polyneuropathy, leading to cold trauma and ulcers on the feet.

Human autoantibodies: probes for nucleolus structure and function.

Abstract: Four distinct nucleolar proteins or RNA-protein complexes have recently been identified as targets of human autoimmune antibodies. These autoantigens areRNA polymer-ase I, PM-Scl (a particle possibly related to preribosomes), 7-2 RNP andfibrillarin (a U3-RNP associated protein). The four different nucleolar autoantigens could be assigned to distinct nucleolar subcompartments by light and electron microscopic immunocytochemistry. RNA polymerase I was located in the fibrillar centers, PM-Scl antigen and 7-2 RNP in the granular component and fibrillarin in the dense fibrillar component. Experimental evidence suggests that these naturally occurring antibodies could be helpful tools in further studying nucleolus structure and functions as well as molecular mechanisms involved in ribosome biogenesis. From a clinical viewpoint, we believe that it is important to identify the nature of reactive autoantigens in systemic autoimmune diseases in order to answer questions concerning the mechanisms which render conserved ubiquitous cellular proteins immunogenic. Revealing such mechanisms in return could give clues with regard to the etiology of certain systemic rheumatic diseases. Ribosome biogenesis, a highly dynamic process with its many well-defined intermediate biological steps related to specific nuclear structures could be amenable for such studies.

Separate localization of sound recognizing and sound producing neural mechanisms in a grasshopper

Abstract: In the two acridid speciesChorthippus parallelus andCh. montanus, the sound template by which females recognize male song varies with temperature, as does the song itself. At relatively high temperatures the females respond best to simulated songs with high syllable frequencies, and at lower temperatures songs with lower syllable frequencies are preferred. The temperature around the supraesophageal and metathoracic ganglia of female grasshoppers was monitored by implanted thermocouples, and either the head or the thorax was warmed selectively while the animal was free to move (within the imits of the wires). Then simulations of the conspecific song varying in syllable frequency corresponding to different song temperatures were presented, and the stridulatory responses of the animals were observed. The results were as follows. 1. Song recognition (in particular, the position of the peak of the response curve) depended on the temperature of the head. 2. The rate of stridulatory hindleg movement was determined by the temperature of the thoracic ganglia. This result provides strong evidence against the genetic coupling hypothesis.

Comparative study of the electronic structure and conduction properties of polypyrrole, polythiophene, and polyfuran and their copolymers

Abstract: A comparative study of the electronic structures and conduction properties of the three heterocyclic polymers polypyrrole, polythiophene, and polyfuran has been carried out using the results of ab initio crystal orbital calculations. Important electronic properties such as band gap, bandwidths, ionization potential, and electron affinity of these polymers are compared. The calculated trend in the values of the gap of the polymers is in excellent agreement with experiment. Our results predict polypyrrole to be the strongest candidate for oxidative (p) doping whereas polythiophene is predicted to have the greatest capacity for reductive (n) doping. It is shown that the electron affinity values depend more on the heterocyclic substitution whereas the values of the ionization potential are more influenced by substitution on the backbone. The problem of the copolymerization of these heterocyclic compounds is examined and the electronic density of states has been determined for various copolymers. The conduction properties of these copolymers are compared and discussed.

Ultrasound findings in Crohn's disease and ulcerative colitis: A prospective study

Abstract: In a prospective study, 118 patients with Crohn's disease, 51 patients with ulcerative colitis, and 72 patients with no disease of the intestine proximal to the rectum were evaluated by ultrasound. In Crohn's disease, thickening of the bowel wall and inflammatory masses were detected in 72.0% of the patients. With a transducer having optimal imaging properties in the near range, these findings were detected in 87.2% of a group of 47 patients. In ulcerative colitis, bowel wall thickening was detected in 52.9% of all patients. Thickening of the bowel wall was more marked in Crohn's disease than in ulcerative colitis. Most pathologic findings in Crohn's disease were located in the right lower abdomen, whereas those in ulcerative colitis were in the left abdomen, in particular in the lower quadrant. The frequency of wall thickening was correlated to the activity of the disease in ulcerative colitis but not in Crohn's disease. Considerably increased wall thickness, when localized in the right lower quadrant and found in combination with inflammatory masses or an abscess, suggests Crohn's disease.

The nature of flows through porous media

Abstract: The present paper points out that the pressure drop of a porous media flow is only due to a small extent to the shear force term usually employed to derive the Kozeny—Darcy law. For a more correct derivation, additional shear terms have to be taken into account since the fluid is also exposed to elongational forces when it passes through the porous media matrix. These are usually not taken into account in the conventional theoretical treatment of flow through porous media as is explained in the literature. This explains why the available theoretical derivations of the Kozeny—Darcy relationship, which are based on one part of the shear-caused pressure drop only, require an adjustment of the constant in the theoretically derived equation to be applicable to experimental results. Details of this derivation are given in this paper and existing derivations are extended to yield better agreement with experiments. To verify experimentally some of the results of the theoretical derivation provided, porous media flows of dilute polymer solutions are studied experimentally. It is shown that the addition of small amounts of high molecular weight polymers to a solvent with Newtonian flow properties causes drastic pressure drop increases if the flow rate exceeds an onset flow rate corresponding to a critical Deborah number of the porous matrix-polymer solution system. This can only be explained if the flow field in the porous medium is exposed to shear and elongational strain. The extent of this interaction is deduced from experimental findings.

OCF--A new coding algorithm for high quality sound signals

Abstract: Optimum Coding in the Frequency domain (OCF) uses entropy coding of quantized spectral coefficients to efficiently code high quality sound signals with 3 bits/sample. In an iterative algorithm psychoacoustic weigthing is used to get the quantization noise to be masked in every critical band. The coder itself uses iterative quantizer control to get each data block to be coded with a fixed number of bits. Details about the OCF-Coder are presented together with information about the codebook needed and the training for the entropy coder. An algorithm for calculating a noise-to-mask ratio is presented which helps to identify, where quantization noise could be audible.

The long-range internal stress field in the dislocation wall structure of persistent slip bands†

Abstract: A detailed model of the long-range internal stress field in the channels of the wall structure of persistent slip bands (PSBs) is developed. It is proposed that the long-range internal stress field consists of a (constant) back stress and an internal forward stress which varies in space and increases from the centre of the channels to the walls. The physical origin of the internal stress field is seen in the constrained configuration of the moving glide dislocations in the channels. The (athermal) cyclic flow stress of PSBs is then expressed easily in terms of the so-called composite model. The proposed model is shown to be in good accord with the available experimental data. A critical assessment of the model in relation to the observed scatter of the local stress data leads to the conclusion that the scatter is due partly to the error of the measurements and to the other part due to real fluctuations. Es wird ein detailliertes Modell des weitreichenden inneren Spannungsfeldes in den Kanalen der Wandstruktur persistenter Gleitbander (PGB) entwickelt. Dabei wird vorgeschlagen, das das weitreichende innere Spannungsfeld sich aus einer (konstanten) Ruckspannung zusammensetzt und aus einer inneren Vorwartsspannung, die raumlich variiert und von der Mitte der Kanale zu den Wanden hin zanimmt. Die Zwangsform der bewegten Gleitversetzungen in den Kanalen wird dabei als physikalische Ursache des inneren Spannungsfeldes betrachtet. Die (athermische) zyklische Fliesspannung der PGB last sich leicht im Rahmen des sogenannten Verbundmodells darstellen. Es wird gezeigt, das das vorgeschlagene Modell in guter Ubereinstimmung mit den vorliegenden experimentellen Daten ist. Aus einer kritischen Betrachtung des Modells bezuglich der beobachteten Streuung der Daten der lokalen Spannung wird geschlossen, das diese Streuung zu einem Teil auf Mesfehler und zum anderen Teil auf tatsachliche Schwankungen zuruckzufuhren ist.

Cell architecture of the dinoflagellate Symbiodinium sp. inhabiting the Hawaiian stony coral Montipora verrucosa

Abstract: The Hawaiian stony coral Montipora verrucosa (Lamarck) Quoy et Gaimard (Anthozoa) harbours zooxanthellae of the genus Symbiodinium Freudenthal (Dinophyceae). The algae occur as coccoid cells when inside their host and produce periodically motile flagellate cells when in culture. Coccoid cells of cultured specimens were investigated in this study, using three-dimensional reconstructions in tandem with quantitative analyses after electron microscopy of serially sectioned cells, as well as freeze-fracture electron microscopy. The amphiesma normally consists of five membraneous layers with intermediate material of unknown composition. The intracellular morphology is characterized by a single, peripheral, multilobed chloroplast with a parallel thylakoid arrangement, polyhedral inclusions resembling carboxysomes, and one double-stalked pyrenoid, outlined by a triple-layered chloroplast envelope. Spherical, elongated or branched mitochondria are aggregated in the center of the cell, surrounded by the chloroplast. The nucleus is a large, spherical structure located rather ventrally and containing 26 chromosomes with ovoid to elongated shapes. Further structures found to be present include Golgi apparatus, fibrous bodies, centrioles, and vacuoles containing crystals. Cell models of Symbiodinium sp. are represented in order to uncover completely the cellular microarchitecture of a gymnodinioid zooxanthella.

Are flash-evoked visual potentials useful for intraoperative monitoring of visual pathway function?

Abstract: Flash-evoked visual potentials (VEPs) recorded from the scalp were used in a series of 35 patients with tumors along the visual pathway: 3 orbital tumors, 25 perisellar tumors, 4 intraventricular tumors, and 3 occipital lesions. Preoperatively, various combinations of impaired visual fields and visual acuity were observed in over 90% of the patients. A postoperative decrease in visual function was observed in 3 cases. Of the 25 perisellar lesions, 13 were operated through a standard frontotemporal craniotomy and 12 were operated through a transnasal-transsphenoidal approach. VEPs were highly susceptible to volatile anesthetics, and there was a significant incidence of spontaneous latency increases and amplitude decreases in a large number of patients. There was an unacceptably high number of cases with significant VEP alteration occurring without concomitant visual function change. During trepanation or the transnasal approach, a reversible potential loss was observed in 11 patients, a profoundly altered wave form was seen in 8 cases, and a loss of single peaks was observed in 15 patients. During dissection of the tumor, a reversible potential loss or a potential with unidentifiable peaks was found in 25 cases; however, the VEPs recovered during closure or in the recovery room. There was no correlation between intraoperative VEP changes and the postoperative changes in visual function. In only 1 patient with an insignificant postoperative decrease in visual acuity from 0.4 to 0.3 was there a concomitant intraoperative potential loss. The major conclusion of our findings is that light-emitting diode flash-evoked VEPs demonstrate intraoperative changes that appear too early and too prominently to be caused solely by manipulation of the optic pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

An interstitial duplication of the X chromosome in a male allows physical fine mapping of probes from the Xq13-q22 region.

Abstract: An insertional translocation into the proximal long arm of the X chromosome in a boy showing muscular hypotony, growth retardation, psychomotor retardation, cryptorchidism, and Pelizaeus-Merzbacher disease (PMD) was identified as a duplication of the Xq21-q22 segment by employing DNA probes. With densitometric scanning for quantitation of hybridization signals, 15 Xq probes were assigned to the duplicated region. Analysis of the duplication allowed us to dissect the X-Y homologous region physically at Xq21 and to refine the assignments of the loci for DXYS5, DXYS12, DXYS13, DXS94, DXS95, DXS96, DXS111, and DXS211. Furthermore, we demonstrated the presence of two different DXYS13 and DXS17 alleles in genomic DNA of our patient, suggesting that the duplication resulted from a meiotic recombination event involving the two maternal X chromosomes.

Classical absorption theory and the development of gastric mucosal damage associated with the non-steroidal anti-inflammatory drugs

Abstract: Evidence has accumulated during the last decade to support the view that the pharmacokinetic behaviour of non-steroidal anti-inflammatory drugs (NSAIDs) contributes not only decisively to their therapeutic effects but also to the type and incidence of their side effects. It has been shown that NSAIDs reach particularly high concentrations in those compartments in which they cause effects and side effects. Specifically, the data reviewed herein indicate that the accumulation of NSAID within gastric mucosal cells a priori is a principal factor associated with the intervention of intracellular biochemical events and resultant gastric mucosal damage. To a large extent this behaviour is according to the precepts of classical absorption theory; in this respect the limitations of such theory are examined. Our survey further indicates that the failure of certain NSAIDs to significantly reduce gastric mucosal levels of prostaglandins (PG) in vivo may reflect pharmacokinetic differences between NSAIDs rather than tissuespecific differences in their potency as inhibitors of cyclooxygenase.

Inhibitory effects of essential oil components on growth of food-contaminating fungi

Abstract: The antifungal activity of several components of essential oils were evaluated using a paper-disk method. The substances investigated are structurally related to eugenol. Equimolar amounts were tested on more than ten fungal strains known to contaminate food. Iso-eugenol, cinnamaldehyde, carvacrol, eugenol and thymol revealed the strongest antifungal activity. The most resistant strain appeared to be Penicillium verrucosum var. cyclopium, and the most sensitive was P. viridicatum. Some of the structural effects were considered, including a free hydroxyl group in connection with an alkyl substituent which seemed to represent an especially active configuration of phenolic compounds and which rendered antimicrobial activity.

Effects of epidermal growth factor, fibroblast growth factor, minoxidil and hydrocortisone on growth kinetics in human hair bulb papilla cells and root sheath fibroblasts cultured in vitro

Abstract: Comparative studies on growth kinetics of cultivated human hair bulb papilla cells (PCs) and hair root sheath fibroblasts (RSFs) yielded evidence of some peculiarities of PCs in both proliferative behavior and morphological growth pattern. As the dermal papilla, essentially supporting the nutrition of matrix epithelium, can be considered a target tissue for agents influencing maintenance of hair growth, we studied the effects of epidermal growth factor (EGF), fibroblast growth factor (FGF), minoxidil (Mino), and hydrocortisone (HC) on the proliferation of PCs and RSFs, both gained from dissected hair follicles of scalp biopsy specimens of two male adults and separately cultured in vitro. EGF and FGF proved to increase proliferation of both PCs and RSFs most, yet at a different intensity for each cell group. HC slowed proliferation, and Mino failed to influence growth of PCs and RSFs.