Objective: To determine whether oocyte activation using a combination of calcium ionophore A23187 (A23187) with puromycin could salvage human unfertilized oocytes after ICSI. Study Design: One hundred and thirteen discarded unfertilized oocytes 20–68 h after ICSI were assigned to four roups: ICSI 20-h group, ICSI 44-h group, ICSI 68-h group and control. All unfertilized oocytes were exposed to A23187 (5 mM) for 5 min and subsequently were incubated with puromycin (10 mg/ml) for 4 h. Sex chromosomal analysis was performed by dual color fluorescence in situ hybridization (FISH). Results: The combination of A23187 with puromycin could activate the unfertilized oocytes 20–68 h after ICSI. The best results were achieved in the ICSI 20-h group, which exhibited an activation rate of 91.2% (31/34), a cleavage rate of 64.7% (22/34) and 44.1% (15/34) high-quality embryos. The activation rate, cleavage rate and the number of high-quality embryos appeared to decrease with the cultured time of unfertilized oocytes after ICSI. FISH analysis showed six embryos with XX and seven embryos with XY in 16 embryos derived from 2PN2PB. Conclusions: The combination of calcium ionophore A23187 with puromycin could effectively salvage unfertilized oocytes within 20 h after ICSI.

Cyclophilin A (CypA), a receptor for the immunosuppressive agent cyclosporin A, is a cis-trans–peptidyl-prolyl isomerase (PPIase). It accelerates the cis-trans isomerization of prolyl-peptide bonds. CypA binds and regulates the activity of a variety of proteins. Atrial natriuretic factor (ANF) and its receptor membrane-bound guanylate cyclase-A (GC-A) are involved in the regulation of blood pressure. We examined whether CypA affects the activation of GC-A by ANF. The results showed that CypA associated with GC-A. Interestingly, binding of ANF to GC-A released CypA. Transfection of CypA inhibited ANF-stimulated GC-A activity, indicating that CypA functions as an endogenous inhibitor for GC-A activation. CypA also inhibits the activity of guanylate cyclase-C (GC-c), the catalytic domain of GC-A, indicating that CypA interacts with the catalytic domain of GC-A. In contrast, transfection of CypA R55A, a CypA mutant expressing low PPIase activity, did not significantly attenuate the activity of GC-c and the activation of GC-A. Inhibition of PPIase activity of CypA with cyclosporin A also blocks the inhibitory effect of CypA on GC-c activity. These results demonstrate that PPIase activity is required for CypA to inhibit GC-c activity and GC-A activation by ANF. Furthermore, mutation of Pro 822, 902, or 958 in GC-c abolished its activity. Therefore, it is likely that CypA binds to GC-A and catalyzes the cis-trans isomerization of Pro 822, 902, or 958, which keeps GC-A in the inactive state, and that binding of ANF to GC-A alters the conformation of the catalytic domain that releases CypA from GC-A leading to enzyme activation.

Success of human oocyte cryopreservation depends on multiple cryobiological factors that could influence the developmental potential of the oocytes. The objective of this study was to examine the effects of different sucrose concentrations on the developmental potential of human frozen–thawed oocytes at different maturity stages. METHODS: A total of 355 oocytes collected from small follicles were randomly divided into three groups and two groups (B and C) were cryopreserved using slow-freezing method. Group A included 131 oocytes at different maturity stages without freezing. Another 119 oocytes in Group B were cryopreserved with 0.1M sucrose and 105 oocytes in Group C with 0.2M sucrose concentration. RESULTS: The post-thaw survival rate of the oocytes and the cleavage rate in Group C were significantly higher than that of Group B (P<0.05). For immature metaphase I (MI) stage oocytes, a significant difference was found in the maturation rate between Group C and Group B (P<0.05). The maturation rate for the GV oocytes in Groups A and C was significantly higher than Group B (P<0.01). CONCLUSIONS: The results suggested that sucrose concentration of 0.2M in the cryoprotectant solution is more suitable for human oocyte cryopreservation.

Besides its involvement in reproductive functions, estrogen protects against the development of cardiovascular diseases. The guanylate cyclase/cGMP system is known to exert potent effects on the regulation of blood pressure and electrolyte balance. We examined whether 17β-estradiol can affect soluble guanylate cyclase in PC12 cells. The results indicate that 17β-estradiol decreases cGMP levels in PC12 cells. 17β-Estradiol decreases sodium nitroprusside (SNP)-stimulated, but not atrial natriuretic factor-stimulated cGMP formation in PC12 cells, indicating that 17β-estradiol decreases cGMP levels by inhibiting the activity of soluble guanylate cyclase. 17β-Estradiol also stimulates protein tyrosine phosphatase activities in PC12 cells and dephosphorylates at least three proteins. Addition of sodium vanadate, a protein tyrosine phosphatase inhibitor, blocks the in ibitory effects of 17β-estradiol on soluble guanylate cyclase activity in PC12 cells. Furthermore, transfection of SHP-1, a protein tyrosine phosphatase, into PC12 cells inhibits both basal and SNP-stimulated guanylate cyclase activity. Amino acid analysis also reveals that the 70-kDa subunit of soluble guanylate cyclase contains the SHP-1 substrate consensus sequence. These results suggest that 17β-estradiol inhibits soluble guanylate cyclase activity through SHP-1.