Selective inhibitors against the 11 families of cyclic nucleotide phosphodiesterases (PDEs) are used to treat various human diseases. How the inhibitors selectively bind the conserved PDE catalytic domains is unknown. The crystal structures of the PDE4D2 catalytic domain in complex with (R)- or (R,S)-rolipram suggest that inhibitor selectivity is determined by the chemical nature of amino acids and subtle conformational changes of the binding pockets. The conformational states of Gln369 in PDE4D2 may play a key role in inhibitor recognition. The corresponding Y329S mutation in PDE7 may lead to loss of the hydrogen bonds between rolipram and Gln369 and is thus a possible reason explaining PDE7's insensitivity to rolipram inhibition. Docking of the PDE5 inhibitor sildenafil into the PDE4 catalytic pocket further helps understand inhibitor selectivity.

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This study examined the misdiagnosis and delayed diagnosis factors for ectopic pregnancy (EP) and heterotopic pregnancy (HP) after in vitro fertilization and embryo transfer (IVF-ET) in an attempt to reduce the diagnostic error. Clinical data of patients who underwent IVF-ET treatment and had clinical pregnancy from 12463 cycles were retrospectively analyzed. Their findings of serum β-hCG test and transvaginal ultrasonography were also obtained during follow-up. These patients were divided into two groups according to the diagnosis accuracy of EP/HP: early diagnosis and misdiagnosis/delayed diagnosis. The results showed that the incidence of EP and HP was 3.8% (125/3286) and 0.8% (27/3286) respectively for IVF/ICSI-ET cycle, and 3.8% (55/1431) and 0.7% (10/1431) respectively for frozen- thawed embryo transfer (FET) cycle. Ruptured EP occurred in 28 patients due to initial misdiagnosis or delayed diagnosis. Related factors fell in 3 categories: (1) clinician factors: misunderstanding of patients' medical history, insufficient training in ultrasonography and unawareness of EP and HP; (2) patient factors: noncompliance with medical orders and lack of communication with clinicians; (3) complicated conditions of EP: atypical symptoms, delayed elevation of serum β-hCG level, early rupture of cornual EP, asymptomatic in early gestation and pregnancy of unknown location. All the factors were interwoven, contributing to the occurrence of EP and HP. It was concluded that complicated conditions are more likely to affect the diagnosis accuracy of EP/HP after IVF-ET. Transvaginal ultrasonography should be performed at 5 weeks of gestation. Intensive follow-up including repeated ultrasonography and serial serum β-hCG tests should be performed in patients with a suspicious diagnosis at admission.

The effects of pituitary suppression with one-third depot of long-acting gonadotropin-releasing hormone (GnRH) agonist in GnRH agonist long protocol for in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) were investigated. A retrospective cohort study was performed on 3186 cycles undergoing IVF/ICSI with GnRH agonist long protocol in a university-affiliated infertility center. The pituitary was suppressed with depot triptorelin of 1.25 mg or 1.875 mg. There was no significant difference in live birth rate between 1.25 mg triptorelin group and 1.875 mg triptorelin group (41.2% vs. 43.7%). The mean luteinizing hormone (LH) level on follicle-stimulating hormone (FSH) starting day was significantly higher in 1.25 mg triptorelin group. The mean LH level on the day of human chorionic gonadotrophin (hCG) administration was slightly but statistically higher in 1.25 mg triptorelin group. There was no significant difference in the total FSH dose between the two groups. The number of retrieved oocytes was slightly but statistically less in 1.25 mg triptorelin group than in 1.875 mg triptorelin group (12.90±5.82 vs. 13.52±6.97). There was no significant difference in clinical pregnancy rate between the two groups (50.5% vs. 54.5%). It was suggested that one-third depot triptorelin can achieve satisfactory pituitary suppression and produce good live birth rates in a long protocol for IVF/ICSI.