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  • 1
    ISSN: 1432-0533
    Keywords: Key words Allograft-inflammatory factor-1 ; Microglia response factor-1 ; Macrophage-inhibiting factor ; related-protein-8/S100A8 ; Traumatic brain injury ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular calcium (Ca2+) has been shown to function as second messenger and to be associated with activation of different cell types including microglia. Previously, in human focal cerebral infarctions an early expression of macrophage-related protein-8 (MRP8/ S100A8), a member of the Ca2+-binding S100-protein family, in microglia has been reported. On the other hand, a delayed activation of microglia was observed following traumatic brain injury (TBI). We therefore examined immunohistochemically microglial expression of MRP8 and allograft inflammatory factor-1 (AIF-1), identical to microglial response factor-1 (mrf-1) and ionized calcium binding adaptor molecule-1 (iba1) in human brains after TBI and in control brains. Both, MRP8 and AIF-1 are Ca2+-binding peptides which have been associated with microglial activation in experimental models and in human cerebral infarctions. Detection of AIF-1 in controls confirmed constitutive expression of this peptide in a subset of microglial cells. After TBI, the density of AIF-1+ microglia did not increase significantly. Lesional expression of AIF-1 did not significantly differ from other brain regions. Furthermore, following TBI, we found no significant differences in the density of AIF-1+ microglia as compared to controls. Microglial MRP8 expression was not detectable in controls and within the first 3 days post TBI, but increased rapidly after 3 days post TBI, suggesting a subpopulation of microglial cells to be AIF-1–/MRP8+. We conclude that the delayed expression of MRP8 and the lack of AIF-1 up-regulation in microglia after TBI is in contrast to ischemic brain lesions and might reflect different activation cascades of microglia.
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  • 2
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary Two mathematical models are considered which generate multimodal interval distributions. They may be applied for the description of interval distributions of unitary discharges of single neurons.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 170 (1962), S. 212-232 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit gehen wir von Dispersionsrelationen fürπ−ℜ-Streuung aus und leiten Gleichungen für die Partialamplituden her, die sich von den entsprechenden Relationen beiChew et al.1 durch folgende Punkte unterscheiden: a) Die Projektion auf die Partialamplituden wird exakt ausgeführt. b) Die Abhängigkeit von der Nukleonmasse wird ebenfalls exakt berücksichtigt. c) WährendChew et al.1 sich auf den 33-Beitrag zum Dispersionsintegral beschränken, vermeiden wir einen großen Teil des dadurch entstehenden Fehlers, indem wir vorher eine Amplitude des Prozessesπ+π→ℜ+ $$\overline \Re $$ subtrahieren, die näherungsweise aus den Daten derπ-π-Resonanz (J=1,I=1) und der totalenπ−ℜ-Querschnitte berechnet werden kann. Die Güte des Verfahrens wird durch einen Vergleich mit der Dispersionsrelation für Vorwärtsstreuung quantitativ geprüft.S,P,D π-ℜ-Partialwellen wurden berechnet. Die Voraussage fürS-Wellen erfolgte bis etwa 100 MeV praktisch ohne Anpassung freier Parameter, insgesamt gesehen sollten die Vorhersagen bis etwa 200 MeV verläßlich sein.
    Notes: Abstract The isospin dependent part of theS-wave pion-nucleon amplitude is calculated according to the CGLN approach, but recoil and projection on the partial waves are treated exactly. Then the difference against the experimental data is approximately a constant up to 100 MeV and amounts to 1/3 of the total value. It is shown, that at low energies the main corrections of the CGLN equations are taken into account by a subtraction of theπ+π→ℜ+ $$\overline \Re $$ ,J=I=1 amplitudesf ± 1 (t) as proposed byMandelstam andFrazer. Calculations have been done forS, P andD pion-nucleon amplitudes. The main result is a prediction of theS-wave amplitude obtained without adjusting free parameters up to 100 MeV. The relations of this method to the equations derived byBowcock, Cottingham andLurié according to the Cini-Fubini approach are discussed.
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  • 4
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The time evolution of atoms or molecules under the influence of a pulse of a single mode laser is most effectively described in the space of quasistationary Floquet states. Separating in this way the fast and slow time scales involved one finds that the time evolution is determined by the singularities in the quasienergy complex plane in strict analogy to the stationary case. Employing the Λ transformation we calculate quasienergies and the corresponding Floquet states perturbatively. We show, for the case of an H2 molecule, that Λ-transformed many body perturbation theory is an excellent tool for the calculation of quasienergies and quasistationary states even for very intense laser fields. We then show that the evolution of the system in an effective two-level subsystem allows for a quantitative calculation of transition probabilities. © 1995 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 408 (2000), S. 513-514 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sir The 300th anniversary year of Swiss mathematician Daniel Bernoulli's birth is an appropriate time to reveal that he was, by a long way, the first to express the proportion of susceptible individuals of an endemic infection in terms of the force of infection and life ...
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  • 6
    ISSN: 1432-1416
    Keywords: Epidemiology ; endemic infectious diseases ; age-dependent contact rates ; transmission potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We present explicit formulas for the transmission potential of an immunizing infection where the contact rates and the vaccination rates depend on the chronological age of an individual, and the infectivity and the recovery rate depend on the duration of an infection.
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  • 7
    ISSN: 1432-1416
    Keywords: Epidemiological models ; Sexually transmitted diseases ; SemiMarkov processes ; Markov chains ; Partnership formation and dissolution ; Expected number of partners during a lifetime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Many deterministic models of sexually transmitted diseases, as well as population models in general, contain elements of stochastic or statistical reasoning. An example of such a model is that of Dietz and Hadeler (1988) concerning sexually transmitted diseases in which there is partnership formation and dissolution. Among the interesting formulas in this paper, which enter into the analysis of the model, are those for the expected number of partners a male or female has during a lifetime. To a probabilist such formulas suggest the possibility that some stochastic process may be constructed so as to yield these formulas as well as others that may be of interest. The principal purpose of this paper is to demonstrate that such a stochastic process does indeed exist in the form of a three state semi-Markov process in continuous time with stationary laws of evolution and with a one-step density matrix determined by four parameters which were interpreted as constant latent risk functions in the classical theory of competing risks. This construction of a semi-Markov process not only provides a framework for the systematic derivation of the formulas of Dietz and Hadeler but also suggests pathways,for extensions to the age-dependent case.
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  • 8
    ISSN: 1432-0878
    Keywords: Key words: Blood-brain barrier ; Glucose transporter (GLUT-1) ; Immunohistochemistry ; Immunogold labeling ; Development ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Electron microscopy was used to quantify the subcellular distribution of the GLUT-1 isoform of the glucose transporter in developing microvessels of the brain of embryonic rats from E (embryonic stage) 13 to E19 and in adult rats. Gold-conjugated secondary antibodies were used to localize, on ultrathin sections of brain, a rabbit polyclonal antiserum (anti-GLUT-1) raised against a synthetic peptide encoding 13 amino acids of the C-terminus of the human glucose transporter. Staining was weak at E13 but increased in density during development into adulthood. The increase represented an increase in the absolute amount of transporter per vessel profile, with a concomitant decrease in vessel size with the narrowing of the wall. At early stages, the percentages of total particles per profile of lumenal membrane, ablumenal membrane, and cytoplasm were approximately equivalent. The ratio of lumenal to ablumenal particle density then shifted from below 1 at E13 to above 2 at E19 and to 4 in the adult. In contrast, vessels of the choroid plexus were devoid of labeling, but the choroid plexus epithelium stained as early as E15. In the brain, no astrocytes, neurons, or pericytes were stained at any stage examined. Developmental upregulation of the GLUT-1 glucose transporter therefore seems to occur at the blood-brain barrier, and the modulation of the subcellular distribution of the transporter can be correlated with other observed changes in the microvessels as they develop the blood-brain barrier phenotype.
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  • 9
    ISSN: 1573-2622
    Keywords: Latencies ; Optic neuritis ; Oral methylprednisolone ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Tübingen study of optic neuritis treatment was started in 1980 to apply new and sensitive tests for monitoring a potential therapeutical steroid effect on the course of acute optic neuritis. Visual evoked potentials were used to assess an effect of oral methylprednisolone in a randomized, controlled trial. Forty-eight patients with acute optic neuritis were treated orally either with methylprednisolone (100 mg per day initially, dosage reduction every 3 days; n = 15) or with thiamine (100 mg per day; n = 33) in the control group, 36 of them in a double-blind procedure. A comparison of the two treatment groups indicated that oral methylprednisolone resulted in a faster improvement in visual evoked potential latency in the initial phase (p = 0.015, 4 weeks after onset), but had no benefit after 12 weeks and 12 months. Follow-up showed different types of courses in the visual evoked potential latencies. The visual evoked potential latencies were correlated to other outcome variables, such as visual evoked potential amplitudes, visual acuity, Aulhorn flicker test and perimetry. We were able to handle nonmeasurable latencies in highly pathologic cases by means of ranks (taking into account censored observations).
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  • 10
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Epaminations. II. Synthesis of Aziridines from Olefins and N-HaloaminesChloramine, dichloramine as well as the N-chloro- and N-bromo-derivatives of primary aliphatic amines react with olefins to give aziridines. Yields up to 75% are obtained by the reaction of N.N-dibromamines with styrene-type olefins. The reaction is shown to proceed stereo-unspecifically by a chain-mechanism with the radical R—N·—Br as the chain carrier.
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