Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In order to detect aneuploidy in interphase human lymphocytes, both in vivo and in vitro, fluorescence in situ hybridization (FISH) was carried out on binucleated cells cytokinesis-blocked by cytochalasin B at the first mitosis after phytohemagglutinin stimulation. A pericentric chromosome-21-specific DNA probe prepared from yeast artificial chromosome clone 881D2 by the polymerase chain reaction was employed. One thousand binucleated cells per individual were scored from cultures from twelve trisomy 21 patients aged 0.01–8.9 years (mean 4.3 years) and 20 normal children of similar age. Of trisomy 21 patients, increased frequencies of disomic cells in vivo (1.690±1.070%) and cells containing six signals with nondisjunction (0.822±0.554%) were found, compared with those of monosomic 21 cells in vivo (0.265±0.130%) and cells containing four signals with nondisjunction in normal children (0.369±0.250%; P=0.000 and P=0.000, respectively). These results show that malsegregation of chromosome 21 occurs more often in trisomic 21 cells than in disomic cells from normal children. The frequency of nondisjunction was significantly higher than the loss of chromosome 21 in both cultured trisomic (0.822±0.554% vs 0.043±0.049%, P=0.000) and disomic (0.369±0.250% vs 0.010±0.030%, P=0.000) cells. Comparisons of in vivo and in vitro data on aneuploidy indicate that a cell selection mechanism may exist in vivo. All these results show that FISH, with a chromosome-specific probe, on binucleated lymphocytes is a powerful tool for simultaneously detecting mosaic cell lines in vivo and malsegregation (loss and nondisjunction) of a corresponding chromosome in vitro in the same cell population.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1433-0385
    Keywords: Schlüsselwörter: Tissue Engineering ; Mesenchymale Stammzellen ; Knochen ; Knorpel. ; Keywords: Tissue engineering ; Mesenchymal stem cells ; Bone ; Cartilage.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Tissue engineering offers the possibility to fabricate living substitutes for tissues and organs by combining histogenic cells and biocompatible carrier materials. Pluripotent mesenchymal stem cells are isolated and subcultured ex vivo and then their histogenic differentiation is induced by external factors. The fabrication of bone and cartilage constructs, their combinations and gene therapeutic approaches are demonstrated. Advantages and disadvantages of these methods are described by in vitro and in vitro testing. The proof of histotypical function after implantation in vivo is essential. The use of autologous cells and tissue engineering methods offers the possibility to overcome the disadvantages of classical tissue reconstruction – donor site morbidity of autologous grafts, immunogenicity of allogenic grafts and loosening of alloplastic implants. Furthermore, tissue engineering widens the spectrum of surgical indications in bone and cartilage reconstruction.
    Notes: Zusammenfassung. Tissue engineering ermöglicht die Herstellung lebender Konstrukte zum Gewebeersatz durch die Kombination histogener Zellen und biokompatiblen Trägermaterialien. Pluripotente mesenchymale Stammzellen können isoliert, ex vivo vermehrt und ihre gewebetypische Differenzierung durch Faktoren induziert werden. Es wird die Herstellung von Knochen- und Knorpelkonstrukten, deren Kombination sowie gentherapeutische Ansätze dargestellt. Vor- und Nachteile der Methoden werden durch in vitro und in vivo Testung beschrieben. Essentiell ist der Nachweis der gewebetypischen Funktion der Konstrukte nach Implantation in den Defekt. Die Verwendung autogener Zellen und Methoden des Tissue engineerings bietet die Möglichkeit die Probleme des klassischen Gewebeersatzes – Morbidität der autogenen Spenderstelle, Immunogenität des allogenen Transplantats und Lockerung von alloplastischen Implantaten – zu überwinden und erweitert das Indikationsspektrum in der rekonstruktiven Chirurgie.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics & optimization 41 (2000), S. 155-170 
    ISSN: 1432-0606
    Keywords: Key words. Maxwell's equations, Exact internal controllability, Multiplier technique, Changing controller. AMS Classification. 93B05, 35L05.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. In this paper we obtain two exact internal controllability results of Maxwell's equations in a general region by using multiplier techniques. The first one is exact controllability in a short time, in which we obtain the ``optimal" (observability) estimates when the location and the shape of the controller is fixed. What happens if we allow the controller to change? Under some conditions, we show that by doing that the system can be exactly controllable within any given time duration, which is our second exact controllability result.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A chitosanase was purified from the culture fluid of the chitino- and chitosanolytic bacterium Burkholderia gladioli strain CHB101. The purified enzyme (chitosanase A) had a molecular mass of 28 kDa, and catalyzed the endo-type cleavage of chitosans having a low degree of acetylation (0–30%). The enzyme hydrolyzed glucosamine oligomers larger than a pentamer, but did not exhibit any activity toward N-acetyl-glucosamine oligomers and colloidal chitin. The gene coding for chitosanase A (csnA) was isolated and its nucleotide sequence determined. B. gladioli csnA has an ORF encoding a polypeptide of 355 amino acid residues. Analysis of the N-terminal amino acid sequence of the purified chitosanase A and comparison with that deduced from the csnA ORF suggests post-translational processing of a putative signal peptide and a possible substrate-binding domain. The deduced amino acid sequence corresponding to the mature protein showed 80% similarity to the sequences reported from Bacillus circulans strain MH-K1 and Bacillus ehimensis strain EAG1, which belong to family 46 glycosyl hydrolases.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-0630
    Keywords: PACS: 61.48.+c; 31.15. Ew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Relativistic discrete-variational local density functional calculations on endohedral Gd@C60, La@C60,Gd@C74, and La@C74 are performed. All the C60- and C74-derivedlevels are lowered upon endohedral Gd and La doping. Both the Gd (4f75d16s2) and La (5d16s2) atoms only donate their two 6s valence electrons to the cages, leaving behind their 5d electrons when they are placed at the cage centers. Compared with large-band-gap C60, small-band-gap C74 and Gd (La)-metallofullerenes have strong both electron-donating and electron-accepting characters, and the calculated ionization potentials and electron affinities for them agree well with the available experimental data.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A novel scheme for secure direct communication between Alice and Bob is proposed, where there is no need for establishing a shared secret key. The communication is based on Einstein-Podolsky-Rosen (EPR) pairs and teleportation between Alice and Bob. After insuring the security of the quantum channel (EPR pairs), Bob encodes the secret message directly on a sequence of particle states and transmits them to Alice by teleportation. In this scheme teleportation transmits Bob’s message without revealing any information to a potential eavesdropper. Alice can read out the encoded messages directly by the measurement on her qubits. Because there is not a transmission of the qubit which carries the secret message between Alice and Bob, it is completely secure for direct secret communication if perfect quantum channel is used.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract By using 188Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO3 and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of 186Re from 186W irradiated by 16 MeV deuterons. No-carrier-added 186ReO4 − saline solution with high specific volume activity was obtained. The overall recovery yield of 186Re was about 85%.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-2072
    Keywords: Key words Nicotine ; Stereoisomer ; Exploratory behaviour ; Body temperature ; Cross-tolerance ; Nicotinic receptor ; NMDA receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study compared the effects of chronic treatment (21 days) with (+)-nicotine and (–)-nicotine on exploratory behaviours and body temperature in rats. Chronic treatment with either (+)- or (–)-nicotine induced tolerance in exploratory behaviours. A cross-tolerance between the two stereoisomers was also observed. Body temperature was differentially affected by chronic (+)- and (–)-nicotine, but cross-tolerance was still observed. In addition, nicotinic acetylcholine receptor (nAChR) and N-methyl-d-aspartate (NMDA) receptor binding in rats treated with (+)- and (–)-nicotine were measured by receptor autoradiography. Chronic treatment with (+)- and (–)-nicotine significantly increased nAChR binding in different brain regions. Furthermore, significant differences in the induction of nAChR binding by chronic (+)- and (–)-nicotine were detected in several brain regions. Chronic treatment with (+)-nicotine significantly increased NMDA receptor binding in the CA1 region of the hippocampus. However, (–)-nicotine had no effect on NMDA receptor binding in any of the regions analysed. These results demonstrate differences between chronic treatment with (+)- and (–)-nicotine in physiological responses such as body temperature and biochemical changes such as changes in nAChRs and NMDA receptor binding, although a cross-tolerance between the two enantiomers in behaviour and body temperature is also observed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 32 (2000), S. 489-502 
    ISSN: 1572-817X
    Keywords: magneto-optic ; THz radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report free-space detection of magnetic pulses via the Faraday effect with shot-noise limited detection. This allows a 10−8 T / √Hz magnetic field resolution. The orthogonal propagation of the optical probe beam and the THz waves demonstrate a 1.3 ps risetime with a 400 GHz frequency bandwidth. The temporal and frequency responses of several crystals are reported with a theoretical response function analysis presented. The dispersion of the magnetic pulse into the sensor crystal is illustrated with a theoretical simulation for comparison. We also contrast the properties of electro-optic sampling with this magneto-optic sampling technique.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1573-2878
    Keywords: minimum-norm points ; quadratic programming ; degeneracy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we propose an efficient algorithm for finding the minimum-norm point in the intersection of a polytope and an affine set in an n-dimensional Euclidean space, where the polytope is expressed as the convex hull of finitely many points and the affine set is expressed as the intersection of k hyperplanes, k≥1. Our algorithm solves the problem by using directly the original points and the hyperplanes, rather than treating the problem as a special case of the general quadratic programming problem. One of the advantages of our approach is that our algorithm works as well for a class of problems with a large number (possibly exponential or factorial in n) of given points if every linear optimization problem over the convex hull of the given points is solved efficiently. The problem considered here is highly degenerate, and we take care of the degeneracy by solving a subproblem that is a conical version of the minimum-norm point problem, where points are replaced by rays. When the number k of hyperplanes expressing the affine set is equal to one, we can easily avoid degeneracy, but this is not the case for k≥2. We give a subprocedure for treating the degenerate case. The subprocedure is interesting in its own right. We also show the practical efficiency of our algorithm by computational experiments.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...