23 research outputs found
Expansion of neopterin and beta2-microglobulin in cerebrospinal fluid reaches maximum levels early and late in the course of human immunodeficiency virus infection
Unterschiede in der Nachweisbarkeit von Humanem Immunschwäche Virus Typ 1 in Tränenflüssigkeit und Blutlymphozyten
Dynamics of the NGC 4636 Globular Cluster System - An extremely dark matter dominated galaxy?
We present the first dynamical study of the globular cluster system of NGC
4636. This giant elliptical galaxy is claimed to be extremely dark matter
dominated, according to X-ray observations. Using the VLT with FORS2/MXU, we
obtained velocities for 174 globular clusters. The clusters have projected
galactocentric distances in the range 4 to 70 kpc, the overwhelming majority
lie within 30 kpc. We find some indication for a rotation of the red
(metal-rich) clusters about the minor axis. Out to a radius of 30 kpc, we find
a roughly constant projected velocity dispersion for the blue clusters of ~200
km/s. The red clusters exhibit a distinctly different behavior: at a radius of
about 13 kpc, the velocity dispersion drops by ~50 km/s to about 170 km/s which
then remains constant out to a radius of 30 kpc.
Using only the blue clusters as dynamical tracers, we perform Jeans-analyses
for different assumptions of the orbital anisotropy. Depending on the
anisotropy and the adopted M/L-values, we find that the dark matter fraction
within one effective radius can vary between 20% and 50% with most a probable
range between 20% and 30%. A main source of uncertainty is the ambiguity of the
velocity dispersion in the outermost bin.
Although the dark halo mass still cannot be strongly constrained, NGC 4636
does not seem to be extremely dark matter dominated. The derived circular
velocities are also consistent with Modified Newtonian Dynamics.Comment: 19 pages, 18 figures. Accepted for publication in A&A. Appendix A
(velocity tables) will be published in the online version of the journa
Impact of vector-priming on the immunogenicity of a live recombinant Salmonella enterica serovar typhi Ty21a vaccine expressing urease A and B from Helicobacter pylori in human volunteers
Orally administered recombinant Salmonella vaccines represent an attractive option for mass vaccination programmes against various infectious diseases. Therefore, it is crucial to gather knowledge about the possible impact of preexisiting immunity to carrier antigens on the immunogenicity of recombinant vaccines. Thirteen volunteers were preimmunized with Salmonella typhi Ty21a in order to evaluate the effects of prior immunization with the carrier strain. Then, they received three doses of 1-2 x 10(10) viable organisms of either the vaccine strain S. typhi Ty21a (pDB1) expressing subunits A and B of recombinant Helicobacter pylori urease (n = 9), or placebo strain S. typhi Ty21a (n = 4). Four volunteers were preimmunized and boosted with the vaccine strain S. typhi Ty21a (pDB1). No serious adverse effects were observed in any of the volunteers. Whereas none of the volunteers primed and boosted with the vaccine strain responded to the recombinant antigen, five of the nine volunteers preimmunized with the carrier strain showed cellular immune responses to H. pylori urease (56%). This supports the results of a previous study in non-preimmunized volunteers where 56% (five of nine) of the volunteers showed a cellular immune response to urease after immunisation with S. typhi Ty21a (pDB1)