83 research outputs found
Modeling human pancreatic beta cell dedifferentiation
Objective: Dedifferentiation could explain reduced functional pancreatic β-cell mass in type 2 diabetes (T2D). Methods: Here we model human β-cell dedifferentiation using growth factor stimulation in the human β-cell line, EndoC-βH1, and human pancreatic islets. Results: Fibroblast growth factor 2 (FGF2) treatment reduced expression of β-cell markers, (INS, MAFB, SLC2A2, SLC30A8, and GCK) and activated ectopic expression of MYC, HES1, SOX9, and NEUROG3. FGF2-induced dedifferentiation was time- and dose-dependent and reversible upon wash-out. Furthermore, FGF2 treatment induced expression of TNFRSF11B, a decoy receptor for RANKL and protected β-cells against RANKL signaling. Finally, analyses of transcriptomic data revealed increased FGF2 expression in ductal, endothelial, and stellate cells in pancreas from T2D patients, whereas FGFR1, SOX,9 and HES1 expression increased in islets from T2D patients. Conclusions: We thus developed an FGF2-induced model of human β-cell dedifferentiation, identified new markers of dedifferentiation, and found evidence for increased pancreatic FGF2, FGFR1, and β-cell dedifferentiation in T2D
Atomic Processes in Planetary Nebulae and H II Regions
Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have
driven much development in atomic physics. In the last few years the
combination of a generation of powerful observatories, the development of ever
more sophisticated spectral modeling codes, and large efforts on mass
production of high quality atomic data have led to important progress in our
understanding of the atomic spectra of such astronomical objects. In this paper
I review such progress, including evaluations of atomic data by comparisons
with nebular spectra, detection of spectral lines from most iron-peak elements
and n-capture elements, observations of hyperfine emission lines and analysis
of isotopic abundances, fluorescent processes, and new techniques for
diagnosing physical conditions based on recombination spectra. The review is
directed toward atomic physicists and spectroscopists trying to establish the
current status of the atomic data and models and to know the main standing
issues.Comment: 9 pages, 1 figur
- …