Category Archives: Leukemia

Changes in Uterine Expression of Leukemia: DISCUSSION(8)

Consequently, the importance of LIF in renewing blastocyst development or implantation in the skunk remains unclear. In other species, addition of recombinant LIF to embryos results in an increased rate of blastocyst formation and survival in vitro. If the function of LIF is similar in the skunk, then uterine LIF concentration might be expected to correlate with the proportion of viable embryos present in the … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(7)

Interleukin-1, tumor necrosis factor, platelet-derived growth factor, transforming growth factor (3, and EGF alter LIF expression in the human uterus. EGF-R mRNA and EGF-induced protein tyrosine kinase activity increase at the time of renewed embryonic development. EGF treatment of skunks with delayed implanting blastocysts seemingly elevated uterine LIF mRNA concentrations to values equivalent to those observed in intact skunks with activated blastocysts. However, the small … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(6)

The time between ovariectomy and initiation of the hormone treatments (6 days) should have been sufficient for steroid-dependent mRNA levels to decline. The apparent lack of LIF mRNA down-regulation after ovariectomy, together with the absence of any inducement or inhibition of LIF expression by steroid treatments in comparison with values in the ovariectomized controls, suggests that uterine LIF is not regulated by either progesterone or … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(5)

Progesterone concentration is highly correlated with that of PRL and increases at the time of renewed blastocyst development. Treatment of ovariectomized skunks with progesterone maintains embryo viability but fails to induce implantation. In the present study, uterine LIF mRNA expression increased at early embryo activation, during which progesterone is the predominant ovarian steroid, suggesting that it might be responsible for the up-regulation of LIF expression. … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(4)

Endocrine regulation of LIF has been investigated in vitro in a few species and in vivo in the sheep and mouse, but no work has been published on the effects of hormones on LIF expression in a carnivore. In the skunk, PRL is the primary pituitary hormone responsible for initiating increased luteal activity and induction of blastocyst implantation. In our experiments, blood PRL concentration exceeded … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(3)

Quantitative comparisons of LIF mRNA concentration were possible by normalizing to the constitutively expressed gene cyclophilin. Increased LIF mRNA concentration relative to that of cyclophilin suggests that LIF is transcriptionally regulated in the skunk uterus. However, in the present study it was not possible to determine whether the change in LIF transcript abundance is due to changes in mRNA synthesis or rate of degradation. Regardless … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(2)

During this period, blastocysts increase in diameter from 1.2 to 1.6 mm; there is then rapid enlargement from 1.7 to > 2.0 mm in diameter 1-2 days before implantation. The strong correlation between blastocyst diameter and developmental state of the embryo, in combination with changes in uterine weight, makes it possible to accurately classify uterine samples and establish the onset and stage of renewed embryonic … Continue reading

Changes in Uterine Expression of Leukemia: DISCUSSION(1)

Our data reveal a significant increase in uterine expression of LIF mRNA and protein in the glandular and luminal epithelium that is temporally correlated with cessation of embryonic diapause and resumption of blastocyst development. The relative lack of detectable LIF protein in the endometrium during embryonic diapause is consistent with our detection of very low concentrations of LIF mRNA by PCR and our inability to … Continue reading

Changes in Uterine Expression of Leukemia: RESULTS(4)

Experiment 2: Hormone Treatments Ovariectomy significantly (p < 0.05) reduced the plasma concentration of progesterone (1.5 ± 0.8 ng/ml) to below that found during embryonic diapause. Silicone elastomer capsules containing progesterone significantly (p < 0.05) increased plasma progesterone to 22.5 ± 9.3 ng/ml and to 26.3 ± 9.8 ng/ml in the group treated with progesterone plus estradiol. Estrogen was nondetectable in all ovariec-tomized control animals. … Continue reading

Changes in Uterine Expression of Leukemia: RESULTS(3)

Immunopositive staining for LIF protein was nondetect-able in the endometrium in four of five animals examined during embryonic diapause (Fig. 3A) and was only faintly detected in the basal portion of the uterine glands in the fifth skunk. LIF protein was first consistently detected in the early activation stage of pregnancy, at which time strong staining was observed in luminal and glandular epithelium (Fig. 3B). … Continue reading