13 research outputs found
The White Mountain Polarimeter Telescope and an Upper Limit on CMB Polarization
The White Mountain Polarimeter (WMPol) is a dedicated ground-based microwave
telescope and receiver system for observing polarization of the Cosmic
Microwave Background. WMPol is located at an altitude of 3880 meters on a
plateau in the White Mountains of Eastern California, USA, at the Barcroft
Facility of the University of California White Mountain Research Station.
Presented here is a description of the instrument and the data collected during
April through October 2004. We set an upper limit on -mode polarization of
14 (95% confidence limit) in the multipole range
. This result was obtained with 422 hours of observations of a 3
sky area about the North Celestial Pole, using a 42 GHz
polarimeter. This upper limit is consistent with polarization predicted
from a standard -CDM concordance model.Comment: 35 pages. 12 figures. To appear in ApJ
Reactive Oxygen Species Hydrogen Peroxide Mediates Kaposi's Sarcoma-Associated Herpesvirus Reactivation from Latency
Kaposi's sarcoma-associated herpesvirus (KSHV) establishes a latent
infection in the host following an acute infection. Reactivation from latency
contributes to the development of KSHV-induced malignancies, which include
Kaposi's sarcoma (KS), the most common cancer in untreated AIDS patients,
primary effusion lymphoma and multicentric Castleman's disease. However,
the physiological cues that trigger KSHV reactivation remain unclear. Here, we
show that the reactive oxygen species (ROS) hydrogen peroxide
(H2O2) induces KSHV reactivation from latency through
both autocrine and paracrine signaling. Furthermore, KSHV spontaneous lytic
replication, and KSHV reactivation from latency induced by oxidative stress,
hypoxia, and proinflammatory and proangiogenic cytokines are mediated by
H2O2. Mechanistically, H2O2
induction of KSHV reactivation depends on the activation of mitogen-activated
protein kinase ERK1/2, JNK, and p38 pathways. Significantly,
H2O2 scavengers N-acetyl-L-cysteine (NAC), catalase
and glutathione inhibit KSHV lytic replication in culture. In a mouse model of
KSHV-induced lymphoma, NAC effectively inhibits KSHV lytic replication and
significantly prolongs the lifespan of the mice. These results directly relate
KSHV reactivation to oxidative stress and inflammation, which are physiological
hallmarks of KS patients. The discovery of this novel mechanism of KSHV
reactivation indicates that antioxidants and anti-inflammation drugs could be
promising preventive and therapeutic agents for effectively targeting KSHV
replication and KSHV-related malignancies