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| 2. |
- Gafvelin, G, et al.
(författare)
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Cytokine and antibody responses in birch-pollen-allergic patients treated with genetically modified derivatives of the major birch pollen allergen Bet v 1
- 2005
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1018-2438 .- 1423-0097. ; 138:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recently, recombinant hypoallergenic derivatives of the major birch pollen allergen, Bet v 1, were used to treat birch-pollen-allergic patients in a double-blind, placebo-controlled, multi-centre immunotherapy study. The aim of this study was to evaluate the effects of vaccination with aluminium-hydroxide-adsorbed recombinant Bet v 1 derivatives versus placebo on T-cell, cytokine and antibody responses in a subgroup of patients. Methods: Blood was drawn from patients of the Swedish centre (n=27; rBet v 1 fragments: n=10; rBet v 1 trimer: n=8, and placebo-aluminium hydroxide: n=9) before the start and after completion of the treatment. PBMC were stimulated with rBet v 1 and analysed for cytokine (IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-gamma)-secreting cells by ELISpot. Bet v 1-specific antibody levels in serum (IgG(1-4), IgE and IgA) were measured by ELISA. Skin prick tests with defined Bet v 1 concentrations were performed before and 10-11 months after the beginning of the study. Results: Bet v 1-specific IgG levels, consisting of IgG 1, IgG 2 and IgG 4, were significantly increased after treatment with recombinant allergen derivatives. Treatment with rBet v 1 trimer led to a significant (p<0.05) reduction of Bet v 1-reactive IL-5- and IL-13-producing cells, reflecting a reduced Th2 response. In addition, a decreased number of Bet v 1-reactive IL-4 producing (p=0.07) and an increase of IL-12-producing (p=0.06) cells was noted in the trimer-treated patients. In contrast to placebo, active treatment resulted in significantly reduced immediate-type skin reactions to Bet v 1 even 10-11 months after treatment. Conclusion: Vaccination with recombinant hypoallergenic Bet v 1 derivatives induces a Bet v 1-specific IgG response and leads to reduced skin reactivity in allergic patients. A reduction of Bet v 1-specific Th2 responses was observed in trimer-treated patients, which may reflect the intrinsic property of this allergen derivative. Copyright (C) 2005 S. Karger AG, Basel.
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| 5. |
- Abramowicz, Marek A, 1945, et al.
(författare)
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A note on the slope-shift anticorrelation in the neutron star kHz QPOs data
- 2005
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Ingår i: n Proceedings of RAGtime 6/7: Workshops on black holes and neutron stars. - 807248334X
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Konferensbidrag (refereegranskat)abstract
- Observations show that the upper νU and lower νL of the ``twin peak'' high frequency QPOs in neutron star sources vary along lines νU = AνL + B in a frequency-frequency plot, and that their ratios νU/νL cluster near the value 3/2. This behaviour is well consistent with the predictions of the non-linear resonance model for QPOs. In this Note, we further explore our recent finding that the coefficients A, B of the frequency-frequency lines for individual sources are anticorrelated. In the (A,B) plane, they occupy rather a narrow region along the line A = 3/2 - B/600 Hz. We show that this observational property of QPOs also follows from the resonance model
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| 6. |
- Abramowicz, Marek A, 1945, et al.
(författare)
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Epicyclic oscillations of fluid bodies: II. Strong gravity
- 2006
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 23:5, s. 1689-1696
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Tidskriftsartikel (refereegranskat)abstract
- Fluids in external gravity may oscillate with frequencies characteristic of the epicyclic motions of test particles. We explicitly demonstrate that global oscillations of a slender, perfect fluid torus around a Kerr black hole admit incompressible vertical and radial epicyclic modes. Our results may be directly relevant to one of the most puzzling astrophysical phenomena-high (hundreds of hertz) frequency quasiperiodic oscillations (QPOs) detected in x-ray fluxes from several black hole sources. Such QPOs are pairs of stable frequencies in the 3/2 ratio. It seems that they originate a few gravitational radii away from the black hole and thus their observations have the potential to become an accurate probe of super-strong gravity.
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| 8. |
- Abramowicz, Marek A, 1945, et al.
(författare)
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The correlations and anticorrelations in QPO data
- 2005
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Ingår i: Astronomische Nachrichten. - : Wiley. - 0004-6337 .- 1521-3994. ; 326:9, s. 864-866
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Tidskriftsartikel (refereegranskat)abstract
- Double peak kHz QPO frequencies in neutron star sources varies in time by a factor of hundreds Hz while in microquasar sources the frequencies are fixed and located at the line ν2 - ν1 in the frequency-frequency plot. The crucial question in the theory of twin HFQPOs is whether or not those observed in neutron-star systems are essentially different from those observed in black holes. In black hole systems the twin HFQPOs are known to be in a 3:2 ratio for each source. At first sight, this seems not to be the case for neutron stars. For each individual neutron star, the upper and lower kHz QPO frequencies, ν2 and ν1, are linearly correlated, ν2 = ν1 + B, with the slope A < 1.5, i.e., the frequencies definitely are not in a 1.5 ratio. In this contribution we show that when considered jointly on a frequency-frequency plot, the data for the twin kHz QPO frequencies in several (as opposed to one) neutron stars uniquely pick out a certain preferred frequency ratio that is equal to 1.5 for the six sources examined so far.
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| 9. |
- Horák, J., et al.
(författare)
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Internal resonance in nonlinear disk oscillations and the amplitude evolution of neutron-star kilohertz QPOs
- 2009
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Ingår i: Astronomy and Astrophysics. ; 499:2, s. 535-540
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Tidskriftsartikel (refereegranskat)abstract
- We study the properties of twin kilohertz quasiperiodic oscillations (QPOs) with a simple toy model consisting of two oscillation modes coupled with a general nonlinear force. We examine resonant effects by slowly varying the values of the tunable, and nearly commensurable, eigenfrequencies. The behavior of the true oscillation frequencies and amplitudes during a slow transition through the 3:2 resonance is examined in detail, and it is shown that both are affected significantly by the nonlinearities in the governing equations. In particular, the amplitudes of oscillations reflect a resonant exchange of energy between the modes, and as a result the initially weaker mode may become dominant after the transition. We note that a qualitatively similar behavior was reported for several neutron-star sources where the difference in the amplitudes of neutron-star twin-peak QPOs changes sign as the observed frequency ratio of the QPOs passes through the value 3:2.
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