302 research outputs found
The functional effects of barium and hypoxia on the in vitro respiratory activity
The hypoxic respiratory response in mammals consists of a transit increase in the respiratory frequency (augmentation phase) followed by a decrease in frequency (depression phase). To understand how the central respiratory system contributes to this response, the in vitro transverse brainstem slice model is used, which contains the pre-Bötzinger Complex, which is responsible for respiratory rhythm generation. The in vitro experiments performed for this thesis provide evidence that external barium exposure alters respiratory activity and significantly increases (P\u3c0.00 1) the voltage of tonic activity under control oxygen conditions (95% FO2). During severe hypoxia (0% FO2), respiratory tonic activity is significantly elevatedduring the depression phase (from 0.55 to 0.95, n=6, P\u3c0.001) by external barium, presumablydue to the closing of K+ channels and a reduction in K+ conductance
RORα Binds to E2F1 to Inhibit Cell Proliferation and Regulate Mammary Gland Branching Morphogenesis
Retinoic acid receptor-related orphan nuclear receptor alpha (RORα) is a potent tumor suppressor that reduces cell proliferation and inhibits tumor growth. However, the molecular mechanism by which it inhibits cell proliferation remains unknown. We demonstrate a noncanonical nuclear receptor pathway in which RORα binds to E2F1 to inhibit cell cycle progression. We showed that RORα bound to the heptad repeat and marked box region of E2F1 and suppressed E2F1-regulated transcription in epithelial cells. Binding of RORα inhibited E2F1 acetylation and its DNA-binding activity by recruiting histone deacetylase 1 (HDAC1) to the protein complexes. Knockdown of HDAC1 or inhibition of HDAC activity at least partially rescued transcription factor activity of E2F1 that was repressed by RORα. Importantly, RORα levels were increased in mammary ducts compared to terminal end buds and inversely correlated with expression of E2F1 target genes and cell proliferation. Silencing RORα in mammary epithelial cells significantly enhanced cell proliferation in the ductal epithelial cells and promoted side branching of the mammary ducts. These results reveal a novel link between RORα and E2F1 in regulating cell cycle progression and mammary tissue morphogenesis
Polarization response of spin-lasers under amplitude modulation
Lasers with injected spin-polarized carriers show an outstanding performance
in both static and dynamic operation. In addition to the intensity response of
conventional lasers, without spin-polarized carriers, both intensity and
polarization of light can be exploited for optical communication in
spin-lasers. However, the polarization dynamics of spin-lasers under amplitude
modulation has been largely overlooked. Here we reveal, analytically and
numerically, a nontrivial polarization response that accompanies the well-known
intensity dynamics of a spin-laser under amplitude modulation. We evaluate the
polarization and intensity response under the same amplitude modulation, and
further assess the capability of such a polarization response in digital data
transfer with eye diagram simulations. Our results provide a more complete
understanding of the modulation response in spin-lasers and open up unexplored
opportunities in optical communication and spintronics.Comment: 7 pages, 4 figures, Applied Physics Letters in pres
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