Use of insulin to increase epiblast cell number: towards a new approach for improving ESC isolation from human embryos

Human embryos donated for embryonic stem cell (ESC) derivation have often been cryopreserved for 5–10 years. As a consequence, many of these embryos have been cultured in media now known to affect embryo viability and the number of ESC progenitor epiblast cells. Historically, these conditions supported only low levels of blastocyst development necessitating their transfer or cryopreservation at the 4–8-cell stage. As such, these embryos are donated at the cleavage stage and require further culture to the blastocyst stage before hESC derivation can be attempted. These are generally of poor quality, and, consequently, the efficiency of hESC derivation is low. Recent work using a mouse model has shown that the culture of embryos from the cleavage stage with insulin to day 6 increases the blastocyst epiblast cell number, which in turn increases the number of pluripotent cells in outgrowths following plating, and results in an increased capacity to give rise to ESCs. These findings suggest that culture with insulin may provide a strategy to improve the efficiency with which hESCs are derived from embryos donated at the cleavage stage.Jared M. Campbell, Michelle Lane, Ivan Vassiliev, and Mark B. Nottl

On polynomially integrable domains in Euclidean spaces

Let $D$ be a bounded domain in $\mathbb R^n,$ with smooth boundary. Denote $V_D(\omega,t), \ \omega \in S^{n-1}, t \in \mathbb R,$ the Radon transform of the characteristic function $\chi_{D}$ of the domain $D,$ i.e., the $(n-1)-$ dimensional volume of the intersection $D$ with the hyperplane $\{x \in \mathbb R^n: =t \}.$ If the domain $D$ is an ellipsoid, then the function $V_D$ is algebraic and if, in addition, the dimension $n$ is odd, then $V(\omega,t)$ is a polynomial with respect to $t.$ Whether odd-dimensional ellipsoids are the only bounded smooth domains with such a property? The article is devoted to partial verification and discussion of this question

New results for two-loop off-shell three-point diagrams

A number of exact results for two-loop three-point diagrams with massless internal particles and arbitrary (off-shell) external momenta are presented. Divergent contributions are calculated in the framework of dimensional regularization.Comment: 10 pages, 3 figures, standard LaTEX (PS-file is also available by anonymous FTP at node VSFYS1.FI.UIB.NO in subdirectory DAVYDYCHEV, the file BERGEN94-03.PS), Bergen Scientific/Technical Report No.1994-0

Development of an improved porcine embryo culture medium for cloning, transgenesis and embryonic stem cell isolation

Work in our laboratory for more than two decades has focussed on the production of genetically modified pigs for xeno transplantion research. More recent work has focussed on the isolation of porcine embryonic stem cells to facilitate this as well as and other research applications. Central to this research has been the production of in vitro Produced (IVP) embryos. These embryos are produced using a twostep culture system based on NCSU23. This culture system which was developed by modifying energy substrate availability and concentrations and by adding non-essential and essential amino acids in a sequential manner. As a result of this work we have developed a culture system that better suits the changing metabolic needs of the pig embryo and produces embryos with relatively high developmental competence compared to the original formulation. These embryos can be used for a range of research applications including the isolation of embryonic stem cells.Luke FS Beebe, Stephen M McIlfatrick, Ivan M Vassiliev and Mark B Nottl