Survivin is essential for fertile egg production and female fertility in mice.

Survivin is the smallest member of the inhibitor of apoptosis protein (IAP) family and acts as a bifunctional protein involved in mitosis regulation and apoptosis inhibition. To identify the physiological role of Survivin in female reproduction, we selectively disrupted Survivin expression in oocytes and granulosa cells (GCs), two major cell types in the ovary, by two different Cre-Loxp conditional knockout systems, and found that both led to defective female fertility. Survivin deletion in oocytes did not affect oocyte growth, viability and ovulation, but caused tetraploid egg production and thus female infertility. Further exploration revealed that Survivin was essential for regulating proper meiotic spindle organization, spindle assembly checkpoint activity, timely metaphase-to-anaphase transition and cytokinesis. Mutant mice with Survivin depleted in GCs showed reduced ovulation and subfertility, caused by defective follicular growth, increased follicular atresia and impaired luteinization. These findings suggest that Survivin has an important role in regulating folliculogenesis and oogenesis in the adult mouse ovary.

Pharmacokinetics, distribution and excretion of PNA in rat by liquid chromatography mass spectrometry method.

The pharmacokinetic profiles, tissue distribution and excretion patterns of PNA in healthy male and female Sprague-Dawley rats following a single intra-duodenum administration were investigated by previously established LC-MS method. Absorption was rapid in rats as evidenced by a short time to maximum concentration (Cmax) of 0.050 ± 0.021, 0.072 ± 0.017 and 0.067 ± 0.018 h at the 25, 50 and 100 mg/kg dose level, respectively. The Cmax were 754.9 ± 196.1, 1187.8 ± 642.1 and 2082.1 ± 1,278.5 ng/mL and the AUC0-4 were 71.8 ± 25.9, 135.2 ± 69.9 and 303.3 ± 198.3 µg/L h, which showed linear with the intra-duodenum administration range from 25-100 mg/kg. Tissues were collected at 4 time points (3, 10 min, 1 and 3 h) after dosing at 50 mg/kg. Compare to the concentrations of plasma and other tissues, the level was particularly high in the liver and brain during 3 h. Bile/urine and feces samples were collected before dosing and till 24/48 h post-dosing. The mean cumulative excretion of unchanged PNA in bile amounted to 0.021% of the dose up to 24 h. The mean recoveries of unchanged PNA were 0.0095% and 0.043% of the dose up to 48 h in urine and feces, respectively. There was no significant difference in PNA concentration observed between male and female rats during the experiments.

A validated method for quantifying entecavir in biological matrices and its application in a pharmacokinetic study in rats and dogs.

A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method that uses ganciclovir as an internal standard (IS) has been developed and validated for quantifying entecavir in rat and dog plasma. Following solid-phase extraction (SPE), the analytes were separated on an Inertsil® ODS-3 (5 µm, 150 mm × 2.1 mm i.d.) column and analyzed in selected ion monitoring (SIM) mode with a positive electrospray ionization (ESI) source using the [M+H]+ ions, 278.1 for entecavir and 256.0 for ganciclovir. The method was validated over the concentration range of 0.01-9 µg/mL for entecavir. All precisions (RSD) within and between batches were less than 10%, and accuracies ranged from 98.1 to 102.5%. The lower limit of quantification was 0.01 µg/mL. The extraction recovery averaged 93.9-96.7%. The validated method was used for a pharmacokinetic study of entecavir in rats and dogs. The following pharmacokinetic parameters were obtained for rats and dogs, respectively: the area under the plasma concentration vs. time curves from time 0 to 24 h (AUC0-24) were 15.4 ± 4.5 and 23.4 ± 7.2 µg∙h/mL; the mean maximum plasma concentration (Cmax) were 2.4 ± 0.8 and 5.0 ± 0.9 µg/mL; the mean time to reach the maximum plasma concentrations (Tmax) were 1.7 ± 0.7 and 1.5 ± 0.4 h; and the mean elimination half-life (t1/2) were 5.3 ± 1.4 and 3.8 ± 1.3 h.