Time to symptomatic vascular stenosis at different locations in patients with arteriovenous grafts.

Most arteriovenous grafts fail due to irreversible thrombosis, superimposed on hemodynamically significant vascular stenosis. Previous studies observed the highest frequency of stenosis at the venous anastomosis, without addressing the timing of stenosis. The present study quantified time to symptomatic stenosis at different vascular locations, and related it to permanent graft failure.

Karyotypic analysis of adult pluripotent stem cells.

Three categories of precursor cells have been identified in postnatal mammals: tissue-committed progenitor cells, germ layer lineage-committed stem cells and lineage-uncommitted pluripotent stem cells. Progenitor cells are the immediate precursors of differentiated tissues. Germ layer lineage stem cells can be induced to form multiple cell types belonging to their respective ectodermal, mesodermal, and endodermal embryological lineages.

Clonogenic analysis reveals reserve stem cells in postnatal mammals. II. Pluripotent epiblastic-like stem cells.

Undifferentiated cells have been identified in the prenatal blastocyst, inner cell mass, and gonadal ridges of rodents and primates, including humans. After isolation these cells express molecular and immunological markers for embryonic cells, capabilities for extended self-renewal, and telomerase activity. When allowed to differentiate, embryonic stem cells express phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin.

Phototropism and local adaptation in Phycomyces sporangiophores.

Phototropic responses to unilateral ultraviolet stimuli were studied to determine whether the response of one side of the cell is affected by the previous exposure of the opposite side to ultraviolet. It has been found that the direction of bending is not parallel to the stimulus direction, but is along a straight line rotated 17 degrees clockwise from the stimulus direction. This deviation indicates that the photoreceptors may be in a state of continual clockwise rotation.