The recent availability in culture of embryo-derived pluripotential cells which exhibit both a normal karyotype and a high differentiative ability has encouraged us to assess the potential of these cells to form functional germ cells following their incorporation into chimaeric mice. We report here the results of blastocyst injection studies using three independently isolated XY embryo-derived cell lines (EK. CP1 , EK. CC1 .1 and EKCC1 .2) which produce a very high proportion (greater than 50%) of live-born animals that are overtly chimaeric. Seven chimaeric male mice, derived from these three lines, have, so far, proved to be functional germ-line chimaeras.

Animals↗

PubMedDate not supplied

Germ-line transmission of genes introduced into cultured pluripotential cells by retroviral vector.

Embryonic stem cells isolated directly from mouse embryos can be cultured for long periods in vitro and subsequently repopulate the germ line in chimaeric mice. During the culture period these embryonic cells are accessible for experimental genetic manipulation. Here we report the use of retroviral vectors to introduce exogenous DNA sequences into a stem-cell line and show that these modified cells contribute extensively to the somatic and germ-cell lineages in chimaeric mice. Compared with current methods for manipulation of the mouse genome, this approach has the advantage that powerful somatic-cell genetic techniques can be used to modify and to select cells with germ-line potential, allowing the derivation of transgenic strains with pre-determined genetic changes. We have by this means inserted many proviral vector sequences that provide new chromosomal molecular markers for linkage studies in the mouse and that also may cause insertional mutations.

Animals↗

PubMedDate not supplied

Echocardiography or cardiac catheterisation--a comparison of risks, benefits and costs.

There are two techniques, echocardiography and cardiac catheterisation, that can be used to evaluate patients with valvular heart disease. This paper describes a comparison of these techniques, in terms of safety, side-effects, quality of imaging and cost. The authors conclude that there are good clinical and economical reasons why echocardiography should be used for evaluating patients with valvular heart disease.

Cardiac Catheterization↗

PubMedDate not supplied

Diphyllobothrium ursi from man in British Columbia--first report of this tapeworm in Canada.

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Adolescent↗