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31.
Pig Reticulocytes. III. Glucose permeability in naturally occurring reticulocytes and red cells from newborn piglets 总被引:1,自引:1,他引:0
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The loss of facilitated glucose transport of red cells occurring in the newborn pig was monitored in 11 density-separated cells from birth to a 4 wk of age. At birth there was a threefold increase in glucose permeability from the lightest cells to the most dense, suggesting that cells having progressively less glucose permeability are released into the circulation as gestation proceeds. Because of extraordinary stimulation of erythropoietic activity, the uppermost top fraction constituting 2-3 percent of the total cells is composed purely of reticulocytes in the growing animal. The glucose permeability of these reticulocytes which at birth has a slow but significant rate of 3.7 μmol/ml cell x min at 25 degrees C is rapidly decreased within 3-4 days to the level of reticulocytes produced in the adult in response to phenylhydrazine assault. Moreover, reticulocytes themselves discard their membrane permeability to glucose in the course of maturation to red cells. Thus, even though reticulocytes at birth are permeable to glucose, they will become red cells practically impervious to glucose within a few days. These findings suggest that the transition from a glucose- permeable fetal state to a glucose-impermeable postnatal state is brought about by two mechanisms: (a) dilution of fetal cells by glucose-impervious cells produced coincidentally with or shortly after birth; and (b) elimination of fetal cells, which have a shorter half-life, from the circulation. 相似文献
32.
Accessing genetic diversity for crop improvement 总被引:1,自引:0,他引:1
33.
Tanja Sigl Gregor Schlamberger Hermine Kienberger Steffi Wiedemann Heinrich HD Meyer Martin Kaske 《Acta veterinaria Scandinavica》2010,52(1):32
Background
Conjugated linoleic acid (CLA) is a collective term for isomers of octadecadienoic acid with conjugated double-bond system. Thus, it was the objective to investigate whether milk composition and metabolic key parameters are affected by adding CLA to the diet of dairy cows in the first four weeks of lactation. 相似文献34.
Better discrimination was possible between phenylthiocarbamide (PTC)
solutions and the pure solvent when the solvent was a tasteless low-
concentration NaCl solution to which the subject had adapted than when the
solvent was purified water. The reverse was true for 6-n- propylthiouracil
(PROP). The differences in discrimination for PROP and PTC in the different
solvents were caused by differences in the intensity and persistence of
aftertastes, rather than a more intense perception of the PTC and PROP
tastes per se. This has consequences for traditional approaches to
measuring taste sensitivity, as well as indicating that PTC and PROP are
not necessarily equivalent indicators of 'taster' versus 'non-taster'
status.
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