87 research outputs found
TGF-β1 and serum both stimulate contraction but differentially affect apoptosis in 3D collagen gels
Apoptosis of fibroblasts may be key for the removal of cells following repair processes. Contraction of three-dimensional collagen gels is a model of wound healing and remodeling. Here two potent inducers of contraction, TGF-β1 and fetal calf serum (FCS) were evaluated for their effect on fibroblast apoptosis in contracting collagen gels. Human fetal lung fibroblasts were cultured in floating type I collagen gels, exposed to TGF-β1 or FCS, and allowed to contract for 5 days. Apoptosis was evaluated using TUNEL and confirmed by DNA content profiling. Both TGF-β1 and serum significantly augmented collagen gel contraction. TGF-β1 also increased apoptosis assessed by TUNEL positivity and DNA content analysis. In contrast, serum did not affect apoptosis. TGF-β1 induction of apoptosis was associated with augmented expression of Bax, a pro-apoptotic member of the Bax/Bcl-2 family, inhibition of Bcl-2, an anti-apoptotic member of the same family, and inhibition of both cIAP-1 and XIAP, two inhibitors of the caspase cascade. Serum was associated with an increase in cIAP-1 and Bcl-2, anti-apoptotic proteins. Interestingly, serum was also associated with an apparent increase in Bax, a pro-apoptotic protein. Blockade of Smad3 with either siRNA or by using murine fibroblasts deficient in Smad3 resulted in a lack of TGF-β induction of augmented contraction and apoptosis. Contraction induced by different factors, therefore, may be differentially associated with apoptosis, which may be related to the persistence or resolution of the fibroblasts that accumulate following injury
Low Radon Concentration Measurement with a Radon-Dissolved Liquid Scintillator Pilot Detector
We construct a high sensitivity radon pilot detector using liquid
scientillator dissolved radon for the CDEX rare-event searches program. The
CDEX-10 project employs a germanium detector array immersed in a massive liquid
nitrogen tank. However, radon emanated from the surface of the tank can
contribute background. As a result, radon contamination in the liquid nitrogen
tank must be regulated and monitored, which necessitates the use of a low-level
Rn measuring device. The radon-dissolved liquid scintillator (LS) detectors
utilizes cascade decay selections, yielding a unique signature. All background
events occurring in the LS, with regard to the system and co-efficiency of Rn
absorption, have been studied. Background activity is mearsured to be
59.818.4 Bq per 300 mL LS. Meanwhile, it shows that radon
concentration absorbed by LS will be saturated and is linearly related to radon
concentration in nitrogen gas. Furthermore, the co-efficiency factor can be
optimized by lowering temperature or raising pressure. Eventually the detection
limit for 222Rn in nitrogen gas is observed to be 9.6 mBq/m^3.Comment: 14 pages, 18 figure
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