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  • 1
    ISSN: 1432-2307
    Keywords: Malignant myoepithelioma ; Pleomorphic adenoma ; Myoepithelial cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Malignant myoepithelioma of the salivary gland is discussed in terms of its clinical behaviour, morphological features and the frequent pre-existence of a pleomorphic adenoma. The study comprised six female and four male patients aged 14–63 years (mean age 38.9 years). Two tumours presented as intraoral lesions and eight were located in the parotid gland. Tumour cells displayed a morphological spectrum ranging from round epithelioid cells to spindle-shaped and stellate cells. Most cells displayed reactivity for high molecular weight keratins and in four tumours there was strong immunoreactivity for smooth muscle actin. Malignant myoepithelioma seems to arise in two different clinical settings: either de novo or in a recurrent pleomorphic adenoma. De novo malignant myoepitheliomas arise in normal salivary gland, tend to be more aggressive and have a short clinical history. Recurrences may not develop or may occur as a single event within a short time interval, and métastases develop in the lungs. Malignant myoepitheliomas arising in recurrent pleomorphic adenomas have a long clinical history, are characterized by multiple recurrences and have to be distinguished from aggressive carcinomas arising in these adenomas. In contrast, the tumours described in the present series arising in pleomorphic adenomas showed local aggressiveness and metastases did not occur until decades after the first treatment. The general opinion that all malignant tumours that arise from pleomorphic adenomas are highly aggressive is not confirmed by the present study.
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  • 2
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The compound acoustic resonator method is used to study the phenomenon of the ferrobielastic transition in single crystals of quartz subjected to uniaxial pressure. Toward this end, a layered structure consisting of an aluminum film/zinc oxide film/aluminum film sandwich was deposited on one of the surfaces of an X-cut plane-parallel quartz plate. This structure served as an electromechanical transducer in such a way that the entire system acted as a multifrequency acoustic resonator. Uniaxial pressure was applied perpendicular to the direction of propagation of the acoustic waves and caused a growth of the frequencies of the resonance peaks of the structures, indicating a change in the velocity of the acoustic waves. The ferrobielastic phase transition, which arises at some threshold pressure (the ferrobielastic switching effect), is characterized by a discontinuous drop in the frequencies of the resonance peaks. The variation of the resonator frequency both below and above the switching threshold correlates with the variation of the so-called “natural” sound velocity determined by the pressure-dependent elasticity constants of the material. The observed frequency jump of the resonance peaks is due mainly to the relatively abrupt change in the dimensions of the crystal. The results of the acoustic measurements allow reliable recording of the switching effect and a study of its properties.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The acid tolerance of Leuconostoc oenos was examined in cells surviving at pH 2.6, which is lower than the acid limit of growth (about pH 3.0). Acid-adapted cells survived better than non-adapted cells. Tolerance to acid stress was found to be dependent upon the adaptive pH. Acid resistance was increased by an order of magnitude for cultures adapted to a pH of about 2.9. Inhibiting protein synthesis with chloramphenicol prior to acid shock revealed that acid adaptation may involve two separate systems, one of which appears to be independent of protein synthesis. The acid- resistant mutant LoV8413, isolated during a long-term survival screen at pH 2.6, was found to be able to grow in acidic media and was characterized by a high H+-ATPase activity at low pH. The data from electrophoretic analysis of total proteins labeled with [35S]methionine indicate that large amounts of a protein of 42 kDa molecular mass were produced within this acid-resistant mutant.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The acid tolerance ofLeuconostoc oenos was examined in cells surviving at pH 2.6, which is lower than the acid limit of growth (about pH 3.0). Acid-adapted cells survived better than non-adapted cells. Tolerance to acid stress was found to be dependent upon the adaptive pH. Acid resistance was increased by an order of magnitude for cultures adapted to a pH of about 2.9. Inhibiting protein synthesis with chloramphenicol prior to acid shock revealed that acid adaptation may involve two separate systems, one of which appears to be independent of protein synthesis. The acid-resistant mutant LoV8413, isolated during a long-term survival screen at pH 2.6, was found to be able to grow in acidic media and was characterized by a high H+-ATPase activity at low pH. The data from electrophoretic analysis of total proteins labeled with [35S] methionine indicate that large amounts of a protein of 42 kDa molecular mass were produced within this acid-resistant mutant.
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  • 5
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: We prove a conjecture by N.N. Nekhoroshev about the long-time stability of elliptic equilibria of Hamiltonian systems, without any Diophantine condition on the frequencies. Higher order terms of the Hamiltonian are used to provide convexity. The singularity of the action-angle coordinates at the origin is overcome by working in cartesian coordinates.
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  • 6
    ISSN: 1432-072X
    Keywords: Transposon5 ; Xylose operon ; Transcriptional fusions ; ColE1 replication ; luxAB genes ; Escherichia coli ; Vibrio harveyi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A ColE1-based plasmid for transcriptional gene fusions was constructed that contains both the promoterless luxAB genes of Vibrio harveyi and a tet marker within the inverted repeats of a left end-truncated Tn5 element. Introduction of this plasmid into an Escherichia coli strain containing a plasmid (pTF421) that overproduces ColE1 RNA1 (and thus inhibits replication of the ColE1 plasmid) allowed selection for cells that had a single copy of the luxAB operon transposed into the chromosome beginning 5 days post-transformation. The long latent period necessary for Tn5 transposition is analogous to that found in other systems, where transposition frequencies and mutation rates increase in a time-dependent manner when selected for upon prolonged incubation on Petri dishes under bacteriostatic conditions.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 25 (2002), S. 459-464 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We analyze here how future solar neutrino experiments could detect neutrino flux fluctuations due to magnetohydrodynamics (MHD) perturbations on the solar plasma. We state that if such time fluctuations are detected, this would provide a unique signature of the resonant spin-flavor precession (RSFP) mechanism as a solution to the solar neutrino problem.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 67 (1996), S. 106-118 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 75 (2000), S. 178-187 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. In this paper we proved that in a baric, power associative, F-algebra of finite dimension, there is an idempotent element of weight 1. When this algebra is alternative, with this idempotent we make the Peirce's decomposition. We define the nil radical as the maximal nil ideal. We proved that the bar-radical is the intersection of the nil radical with the square of $bar({\cal a})$ . All the results are naturally true for baric associative algebras of finite dimension.
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  • 10
    ISSN: 1573-904X
    Keywords: lidocaine ; conformations ; infrared (IR) ; nuclear magnetic resonance (NMR) ; hydrogen bonding ; partition coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract IR and 1H NMR studies in CDCl3 and CCl4 of a series of tertiary aminoxylidides with the amino group in the 2 to 6 position of the acyl chain are described. Lidocaine, diethylaminoaceto-2′,6′-xylidide, forms an intramolecular five-membered ring hydrogen-bonded monomer at all concentrations in both solvents. β-Diethyl-amino-propiono-2′,6′-xylidide forms an intramolecular six-membered ring hydrogen-bonded monomer in CDCl3 and CCl4 but a trans intermolecularly associated species is the major form present at high concentrations in CCl4. The longer-chain homologues are mixtures of nonassociated trans and cis monomers at low concentrations but associated trans forms predominate at high concentrations. Evidence for the presence of a hydrogen-bonded seven-membered ring intramolecular monomer in CDCl3 for γ-diethylaminobutyro-2′,6′-xylidide is presented. The relationship between the molecular conformation and the partition coefficient is discussed.
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