| 1. |
|
|
| 2. |
- Andersson, Jenny, 1976, et al.
(author)
-
The Volume Fraction of a Non-overlapping Germ-grain Model
- 2006
-
In: Electronic Communications in Probability. - 1083-589X. ; 11, s. 78-88
-
Journal article (peer-reviewed)abstract
- We discuss the volume fraction of a model of non--overlapping convex grains. It is obtained from thinning a Poisson process where each point has a weight and is the centre of a grain, by removing any grain that is overlapped by one of larger or equal weight. In the limit as the intensity of the Poisson process tends to infinity, the model can be identified with the intact grains in the dead leaves model if the weights are independent of the grain sizes. In this case we can show that the volume fraction is at most $1/2^d$ for $d=1$ or $2$ if the shape is fixed, but the size and the orientation are random. The upper bound is achieved for centrally symmetric sets of the same size and orientation. For general $d$ we can show the upper bound, $1/2^d$, for spherical grains with two--point radius distribution. If dependence between weight and size is allowed, it is possible to achieve a volume fraction arbitrarily close to one.
|
|
| 3. |
- Eriksson, Ulrika, et al.
(author)
-
Metalloproteinase activity is the sole factor responsible for the growth-promoting effect of conditioned medium in Trichoplusia ni insect cell cultures
- 2005
-
In: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 119:1, s. 76-86
-
Journal article (peer-reviewed)abstract
- Conditioned medium (CM) taken from a serum-free culture of Trichoplusia ni (BTI-Tn-5B 1-4, High Five) cells on days 2 and 3, shortened the lagphase and increased the maximum cell density when added to T ni cultures with low-inoculum cell density. Gel filtration fractions of CM, eluting at around 45 kDa, stimulated cell proliferation even better than CM. A protein in the gel filtration fraction was identified by N-terminal amino acid sequencing as a proteinase, related to a snake venom metalloproteinase. Casein zymography showed, multiple metalloproteinase bands between 48 and 25 kDa, as well as precursor forms above 48 kDa. Metalloproteinase bands below the main band at 48 kDa were autocatalytic degradation products. Metalloproteinase activity was the sole factor responsible for the growth stimulating effect of CM as shown by using the specific metalloproteinase inhibitor DL-thiorphan. Metalloproteinases have recently been shown to release growth factors from sequestering extracellular proteins. We propose that the metalloproteinase is involved in autocrine regulation of T ni proliferation in serum-free media. In addition, a gel filtration fraction of CM, eluting at about 10 kDa, inhibited cell growth. Apart from a lysozyme precursor protein and a cyclophilin-like protein, a kazal-type proteinase inhibitor could be identified in this fraction.
|
|
