Design, Synthesis, and Evaluation of Dihydropyrimidine Derivatives as Selective PDE1 Inhibitors for the Treatment of Liver Fibrosis.

Liver fibrosis is a common pathological feature of most chronic liver diseases with no effective drugs available. Phosphodiesterase 1 (PDE1), a subfamily of the PDE super enzyme, might work as a potent target for liver fibrosis by regulating the concentration of cAMP and cGMP. However, there are few PDE1 selective inhibitors, and none has been investigated for liver fibrosis treatment yet. Herein, compound AG-205/1186117 with the dihydropyrimidine scaffold was selected as the hit by virtual screening. A hit-to-lead structural modification led to a series of dihydropyrimidine derivatives. Lead 13h exhibited the IC50 of 10 nM against PDE1, high selectivity over other PDEs, as well as good safety properties. Administration of 13h exerted significant anti-liver fibrotic effects in bile duct ligation-induced fibrosis rats, which also prevented TGF-ß-induced myofibroblast differentiation in vitro, confirming that PDE1 could work as a potential target for liver fibrosis.

Discovery of novel selective phosphodiesterase­1 inhibitors for the treatment of acute myelogenous leukemia.

Acute myelogenous leukemia (AML) is the most common form of acute leukemia in adults. PDE1 (Phosphodiesterase 1) is a subfamily of the PDE super-enzyme families that can hydrolyze the second messengers cAMP and cGMP simultaneously. Previous research has shown that suppressing the gene expression of PDE1 can trigger apoptosis of human leukemia cells. However, no selective PDE1 inhibitors have been used to explore whether PDE1 is a potential target for treating AML. Based on our previously reported PDE9/PDE1 dual inhibitor 11a, a series of novel pyrazolopyrimidinone derivatives were designed in this study. The lead compound 6c showed an IC50 of 7.5 nM against PDE1, excellent selectivity over other PDEs and good metabolic stability. In AML cells, compound 6c significantly inhibited the proliferation and induced apoptosis. Further experiments indicated that the apoptosis induced by 6c was through a mitochondria-dependent pathway by decreasing the ratio of Bcl-2/Bax and increasing the cleavage of caspase-3, 7, 9, and PARP. All these results suggested that PDE1 might be a novel target for AML.

Accelerating and Automating the Free Energy Perturbation Absolute Binding Free Energy Calculation with the RED-E Function.

The accurate prediction of the binding affinities between small molecules and biological macromolecules plays a fundamental role in structure-based drug design, which is still challenging. The free energy perturbation-based absolute binding free energy (FEP-ABFE) approach has shown potential in its reliability. To correctly calculate the energy related to the ligand being restrained by the receptor, additional restraints between the ligand and the receptor are needed. However, determining the restraint parameters for individual ligands empirically is too trivial to be automated, and usually gives rise to numerical instabilities, which set back the applications of FEP-ABFE. To address these issues, we derived the analytical expression for the probability distribution of energy differences, P(ΔU), during the process of restraint addition, which is called the RED-E (restraint energy distribution at equilibrium position) function. Simulations indicated that the RED-E function can accurately describe P(ΔU) when restraints are added at the equilibrium position. Based on the RED-E function, an automatic restraint selection method was proposed to select the best restraint. With this method, there is a high phase-space overlap between the free and restrained states, such that using a 2-λ perturbation can accurately calculate the free energy of the restraint addition, which is a nearly 6 times acceleration compared with current widely used 12-λ perturbation method. The RED-E function gives insight into the non-Gaussian behavior of the sampled P(ΔU) in certain FEP processes in an analytical way. The highly automated and accelerated restraint selection also makes it possible for the large-scale application of FEP-ABFE in real drug discovery practices.

Identification of Novel Quinolin-2(1H)-ones as Phosphodiesterase 1 Inhibitors for the Treatment of Inflammatory Bowel Disease.

Phosphodiesterase 1 (PDE1) is a subfamily of PDE super enzyme families that can hydrolyze cyclic adenosine monophosphate and cyclic guanosine monophosphate simultaneously. Currently, the number of PDE1 inhibitors is relatively few, significantly limiting their application. Herein, a novel series of quinolin-2(1H)-ones were designed rationally, leading to compound 10c with an IC50 of 15 nM against PDE1C, high selectivity across other PDEs, and remarkable safety properties. Furthermore, we used the lead compound 10c as a chemical tool to explore whether PDE1 could work as a novel potential target for the treatment of inflammatory bowel disease (IBD), a disease which is a chronic, relapsing disorder of the gastrointestinal tract inflammation lacking effective treatment. Our results showed that administration of 10c exerted significant anti-IBD effects in the dextran sodium sulfate-induced mice model and alleviated the inflammatory response, indicating that PDE1 could work as a potent target for IBD.

Gender differences in the associations between body mass index, depression, anxiety, and stress among endocrinologists in China.

BACKGROUND: Depression, anxiety, and stress symptoms have been found to be associated with overweight or obesity, but the gender differences in the associations have not been well-examined. Based on a national sample of endocrinologists in China, we examined such associations with a focus on gender differences. METHODS: Data were collected from endocrinologists in China using an online questionnaire, which included demographic data, body weight, and height. Depression, anxiety, and stress symptoms were assessed using the Depression, Anxiety, and Stress Scale-21 (DASS-21). RESULTS: In total, 679 endocrinologists (174 males and 505 females) completed the survey. One-fourth (25.6%) were classified as overweight, with a significant gender difference (48.9% in males vs. 17.6% in females, p < 0.05). Overall, 43.4% of the participants endorsed probable depressive symptoms (54.6% in males and 39.6% in females, p = 0.004), 47.6% for anxiety (51.7% in males vs. 46.1% in females, p = 0.203), and 29.6% for stress symptoms (34.5% in males vs. 27.92% in females, p = 0.102). After controlling for confounders, in the whole group, male gender (aOR = 4.07, 95% CI:2.70-6.14, p < 0.001), depression (aOR = 1.05, 95% CI:1.00-1.10, p = 0.034) and age (aOR = 1.03, 95% CI:1.00-1.05, p = 0.018) were positively associated with overweight. In males, depression (aOR = 1.14, 95% CI:1.05-1.25, p = 0.002), administration position (aOR = 4.36, 95% CI:1.69-11.24, p = 0.002), and night shifts/month (aOR = 1.26, 95% CI:1.06-1.49, p = 0.008) were positively associated with overweight, while anxiety (aOR = 0.90, 95% CI:0.82-0.98, p = 0.020) was negatively associated with overweight. In females, only age (aOR = 1.04, 95% CI:1.01-1.07, p = 0.014) was significantly associated with overweight status, while depression and anxiety were not associated with overweight. Stress symptoms were not associated with overweight in either gender. CONCLUSIONS: One-fourth of endocrinologists in China are overweight, with a rate in males nearly triple the one in females. Depression and anxiety are significantly associated with overweight in males but not females. This suggests possible differences in the mechanism. Our findings also highlight the need to screen depression and overweight in male physicians and the importance of developing gender-specific interventions.

Discovery of novel phosphodiesterase-1 inhibitors for curing vascular dementia: Suppression of neuroinflammation by blocking NF-κB transcription regulation and activating cAMP/CREB axis.

Vascular dementia (VaD) is the second commonest type of dementia which lacks of efficient treatments currently. Neuroinflammation as a prominent pathological feature of VaD, is highly involved in the development of VaD. In order to verify the therapeutic potential of PDE1 inhibitors against VaD, the anti-neuroinflammation, memory and cognitive improvement were evaluated in vitro and in vivo by a potent and selective PDE1 inhibitor 4a. Also, the mechanism of 4a in ameliorating neuroinflammation and VaD was systematically explored. Furthermore, to optimize the drug-like properties of 4a, especially for metabolic stability, 15 derivatives were designed and synthesized. As a result, candidate 5f, with a potent IC50 value of 4.5 nmol/L against PDE1C, high selectivity over PDEs, and remarkable metabolic stability, efficiently ameliorated neuron degeneration, cognition and memory impairment in VaD mice model by suppressing NF-κB transcription regulation and activating cAMP/CREB axis. These results further identified PDE1 inhibition could serve as a new therapeutic strategy for treatment of VaD.

Structure-based discovery of orally efficient inhibitors via unique interactions with H-pocket of PDE8 for the treatment of vascular dementia.

Our previous study demonstrated that phosphodiesterase 8 (PDE8) could work as a potential target for vascular dementia (VaD) using a chemical probe 3a. However, compound 3a is a chiral compound which was obtained by chiral resolution on HPLC, restricting its usage in clinic. Herein, a series of non-chiral 9-benzyl-2-chloro-adenine derivatives were discovered as novel PDE8 inhibitors. Lead 15 exhibited potent inhibitory activity against PDE8A (IC50 = 11 nmol/L), high selectivity over other PDEs, and remarkable drug-like properties (worthy to mention is that its bioavailability was up to 100%). Oral administration of 15 significantly improved the cAMP level of the right brain and exhibited dose-dependent effects on cognitive improvement in a VaD mouse model. Notably, the X-ray crystal structure of the PDE8A-15 complex showed that the potent affinity and high selectivity of 15 might come from the distinctive interactions with H-pocket including T-shaped π-π interactions with Phe785 as well as a unique H-bond network, which have never been observed in other PDE-inhibitor complex before, providing new strategies for the further rational design of novel selective inhibitors against PDE8.

Structural Modifications of Nimodipine Lead to Novel PDE1 Inhibitors with Anti-pulmonary Fibrosis Effects.

Our previous research demonstrated that phosphodiesterase-1 (PDE1) could work as a potential target against idiopathic pulmonary fibrosis. Nimodipine, a calcium antagonist commonly used to improve hypertension, was reported to have inhibition against PDE1. Herein, a series of nimodipine analogues were discovered as novel selective and potent PDE1 inhibitors after structural modifications. Compound 2g exhibited excellent inhibitory activity against PDE1C (IC50 = 10 nM), high selectivity over other PDEs except for PDE4, and weak calcium channel antagonistic activity. Administration of compound 2g exhibited remarkable therapeutic effects in a rat model of pulmonary fibrosis induced by bleomycin and prevented myofibroblast differentiation induced by TGF-ß1. The expressions of PDE1B and PDE1C were found to be increased and concentrated in the focus of fibrosis. Compound 2g increased the levels of 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) in the lungs of rats with pulmonary fibrosis, supporting the fact that the anti-fibrosis effects of 2g were through the regulation of cAMP and cGMP.

Gender Differences in Burnout Among Endocrinologists in China.

Objective: To survey the prevalence of burnout in a national sample of endocrinologists in China and to examine its correlates, with a special focus on gender differences. Methods: An anonymous online survey was conducted among endocrinologists in 31 provincial government-owned "People's Hospitals" of each province in mainland China. Demographic and work-related factors were collected from participants. The Maslach Burnout Inventory-Human Services Survey (MBI-HSS) was used to assess burnout, including emotional exhaustion (EE), depersonalization (DP), and reduced personal accomplishment (PA). Results: A total of 711 endocrinologists (72.1% were female and mean age was 39.63 ± 8.51 years old) completed the survey. Burnout was reported by 32.8% of the participants. There were no significant gender differences in the overall prevalence of burnout or EE, DP, and PA (all p > 0.05). A multi-level linear regression revealed: (1) In male participants, PA was significantly associated with age (ß = 0.03, p = 0.003), DP was inversely associated with age (ß = -0.06, p = 0.005), EE was significantly associated with shorter sleep duration (ß = -0.25, p = 0.006), and longer work hours (ß = 0.01, p = 0.016). (2) In females, PA was significantly associated with age (ß = 0.01, p = 0.038), EE and DP were both significantly associated with shorter sleep duration (ß = -0.19, p = 0.001; and ß = -0.15, p = 0.011, respectively). EE and DP were also associated with work hours (ß = 0.02, p < 0.001; and ß = 0.01, p < 0.001, respectively). Conclusion: Nearly one-third of endocrinologists in China experienced burnout. Although there were no significant gender differences in the prevalence of overall burnout or EE, DP, and PA scores, male and female participants differed in factors associated with EE, DP, and PA. Interventions need to be tailored to target different aspects in male and female endocrinologists and target different subgroups.

PDE1 inhibitors: a review of the recent patent literature (2008-present).

INTRODUCTION: PDE1 has been demonstrated to be a potential drug target for a variety of diseases, such as Alzheimer's disease and cardiovascular disease. In the past decades, numerous PDE1 inhibitors with structural diversities have been developed and patented by pharmaceutical companies, providing drug candidates for exploring novel disease indications of PDE1. AREA COVERED: This review aims to provide an overview of PDE1 inhibitors reported in patents from 2008 to present. EXPERT OPINION: Among current PDE1 inhibitors, only a few of them showed high selectivity over other PDEs, which might cause severe side effects in the clinic. The development of highly selective PDE1 inhibitors is still the 'top priority' in the following research. The selective recognition mechanism of PDE1 with inhibitors should be further elucidated by X-ray crystallography in order to provide evidence for the rational design of selective PDE1 inhibitors. In addition, PDE1 inhibitors should be applied to different clinical indications beyond CNS diseases.

Circulating circTOLLIP serves as a diagnostic biomarker for liquid biopsy in non-small cell lung cancer.

BACKGROUND: Circular RNAs (CircRNAs) have been found to possess vital functions in tumorigenesis of various cancer types, including non-small cell lung cancer (NSCLC). The aim of this study was to identify and explore the diagnostic values of the newly found Toll interacting protein (TOLLIP)-derived circRNA (circTOLLIP) for liquid biopsy in NSCLC. METHODS: RNase R and actinomycin D assays were conducted to confirm the existence and stability of circTOLLIP. RT-qPCR was performed to identify the expression levels of circTOLLIP in NSCLC tumor tissues, whole blood, and cell lines. The diagnostic values were evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: CircTOLLIP was screened as a candidate biomarker and was found to be significantly down-regulated in both NSCLC tissues and cell lines. Interestingly, circulating circTOLLIP was also lower-expressed in the whole blood of patients with NSCLC compared to that of patients with benign lung disease and healthy controls. Importantly, the circulating circTOLLIP represented better diagnostic values in comparison to the traditional tumor markers (NSE, CYFR21-1, and CA72-4), and showed higher stability even though the whole blood was exposed to various tough conditions. CONCLUSIONS: Our findings indicate that circTOLLIP can be used as a non-invasive biomarker to distinguish early-stage NSCLC from benign lung diseases and from healthy controls, suggesting the potential application of circTOLLIP for liquid biopsy in NSCLC.

The Prevalence and Associated Factors of Short Sleep Duration Among Nurses in Tertiary Public Hospitals in China: Findings from a National Survey.

BACKGROUND: Sleep is an essential component of health and well-being. Short sleep duration may negatively affect nurses' health and patients' safety. OBJECTIVE: To investigate the sleep duration and subjective satisfaction with sleep duration among nurses in tertiary public hospitals in China and to explore the associated factors. METHODS: This cross-sectional study was conducted between December 18 and 31, 2017 in 136 major public hospitals from 31 provinces in mainland China. An online anonymous questionnaire was delivered through WeChat. Totally 27,575 nurses completed the survey. RESULTS: The response rate was 95.46%. The mean reported total sleep duration was 6.67±0.97 hours per day. About 46.87% (n=12,924) reported having short sleep duration (SSD, less than 7 hours per day), and 27.63% (n=7618) were not satisfied with their sleep duration. In the SSD group, 45.67% (n=5902) were dissatisfied with their sleep duration. SSD was significantly associated with sociodemographic factors, including an older age, having more than one child, being divorced or separated, and job-related factors, including longer working hours, more night shifts and heavy workload. CONCLUSION: Nearly half of the nurses in the public hospitals in China reported sleeping less than 7 hours, and more than one quarter were dissatisfied with their sleep duration. Interventions are needed to improve Chinese nurses' sleep, including reducing working hours, night shifts or workload.

Discovery of Potent Phosphodiesterase-9 Inhibitors for the Treatment of Hepatic Fibrosis.

Hepatic fibrosis commonly exists in chronic liver disease and would eventually develop to cirrhosis and liver cancer with high fatality. Phosphodiesterase-9 (PDE9) has attracted profound attention as a drug target because of its highest binding affinity among phosphodiesterases (PDEs) with cyclic guanosine monophosphate. However, no published study has reported PDE9 inhibitors as potential agents against hepatic fibrosis yet. Herein, structural modification from a starting hit LL01 led to lead 4a, which exhibited an IC50 value of 7.3 nM against PDE9, excellent selectivity against other PDE subfamilies, and remarkable microsomal stability. The cocrystal structure of PDE9 with 4a revealed an important residue, Phe441, capable of improving the selectivity of PDE9 inhibitors. Administration of 4a exerted a significant antifibrotic effect in bile duct-ligation-induced rats with hepatic fibrosis and transforming growth factor-ß-induced fibrogenesis. This therapeutic effect was indeed achieved by selectively inhibiting PDE9 rather than other PDE isoforms, identifying PDE9 inhibitors as potential agents against hepatic fibrosis.

Design, Synthesis, and Evaluation of Dihydropyranopyrazole Derivatives as Novel PDE2 Inhibitors for the Treatment of Alzheimer's Disease.

Phosphodiesterase 2 (PDE2) has been regarded as a novel target for the treatment of Alzheimer's disease (AD). In this study, we obtained (R)-LZ77 as a hit compound with moderate PDE2 inhibitory activity (IC50 = 261.3 nM) using a high-throughput virtual screening method based on molecular dynamics. Then, we designed and synthesized 28 dihydropyranopyrazole derivatives as PDE2 inhibitors. Among them, compound (+)-11h was the most potent PDE2 inhibitor, with an IC50 value of 41.5 nM. The molecular docking of PDE2-(+)-11h reveals that the 4-(trifluoromethyl)benzyl)oxyl side chain of the compound enters the H-pocket and forms strong hydrophobic interactions with L770/L809/F862, which improves inhibitory activity. The above results may provide insight for further structural optimization of highly potent PDE2 inhibitors and may lay the foundation for their use in the treatment of AD.

Discovery of Highly Specific Catalytic-Site-Targeting Fluorescent Probes for Detecting Lysosomal PDE10A in Living Cells.

A challenge for sensors targeting specific enzymes of interest in their native environment for direct imaging is that they rationally exploit a highly selective fluorescent probe with a high binding affinity to provide real-time detection. Immunohistochemical staining, proteomic analysis, or recent enzymatic fluorescent probes are not optimal for tracking specific enzymes directly in living cells. Herein, we introduce the concept of designing a highly effective fluorescent probe (BVQ1814) targeting phosphodiesterase 10A with a highly potent affinity and a >1000-fold subfamily selectivity by gaining insights into the three-dimensional structural information of the active site of the catalytic pocket. BVQ1814 showed an outstanding binding affinity for PDE10A in vitro and specifically detected PDE10A in living cells, indicating that most PDE10A was probably distributed in the lysosomes. We validated the PDE10A distribution in stable mCherry-PDE10A-overexpressing HepG2 cells. This probe delineated the profile of PDE10A in tissue sections and exhibited a remarkable therapeutic effect as a PDE10A inhibitor for treating pulmonary arterial hypertension. This concept will open up a new avenue for designing a highly effective fluorescent probe for tracking receptor proteins by taking full advantage of the structural information in the ligand-binding pocket of the target of interest.

Gender Differences in Job Satisfaction and Work-Life Balance Among Chinese Physicians in Tertiary Public Hospitals.

Background: Gender has been associated with job-related experience, including job satisfaction and work-life balance. This study aimed to identify gender differences in job satisfaction and work-life balance among Chinese physicians in a large, nationally representative sample. Methods: A national cross-sectional survey was conducted between March 18 and 31, 2019, using an anonymous online questionnaire. The questionnaire included the short-form MSQ (Chinese version) and a work-life balance item. The demographic and job-related factors were also collected. Findings: In total, 22,128 physicians (9,378 males and 12,750 females) from 144 tertiary public hospitals completed the survey. The overall MSQ score (job satisfaction) was 70.31 ± 12.67, and it was 69.89 ± 13.24 in males, and 70.63 ± 12.22 in females, respectively (p < 0.001). Only 931 (4.21%) physicians were very satisfied with WLB (421 males, 510 females), and 2,534 (11.45%) were rated as satisfied. Age, education, monthly income, working hours, specialty, and professional titles were significantly associated with job satisfaction; while number of children, specialty, professional titles, monthly income, age, working hours were significantly associated with WLB. No significant gender differences were observed in job satisfaction or WLB after controlling confounding factors (both p > 0.05). Interpretation: While many demographic and work-related factors are significantly associated with job satisfaction and WLB, we found no significant gender differences, which is different from many other studies. To improve Chinese physicians' job satisfaction and work-life balance, interventions should be focused on certain specialties and on other modifiable factors, such as income, working hours.

Discovery of effective phosphodiesterase 2 inhibitors with antioxidant activities for the treatment of Alzheimer's disease.

The multi-target-directed-ligand (MTDL) strategy has been widely applied in the discovery of novel drugs for the treatment of Alzheimer's disease (AD) because of the multifactorial pathological mechanisms of AD. Phosphodiesterase-2 (PDE2) has been identified to be a novel and promising target for AD. However, MTDL combining with the inhibitory activity against PDE2A and other anti-AD factors such as antioxidants has not been developed yet. Herein, a novel series of PDE2 inhibitors with antioxidant capacities were designed, synthesized, and evaluated. Most compounds showed remarkable inhibitory activities against PDE2A as well as antioxidant activities. Compound 6d was selected, which showed good IC50 of 6.1 nM against PDE2A, good antioxidant activity (ORAC (Trolox) = 8.4 eq.) and no cytotoxicity to SH-SY5Y cells. Molecular docking and dynamics simulations were applied for the rational design and explanation of structure-activity relationship (SAR) of lead compounds.

Sleep duration and satisfaction among physicians in tertiary public hospitals in China: a large sample national survey.

OBJECTIVES: To investigate the sleep duration and level of satisfaction among physicians in tertiary public hospitals in China, and to explore associated factors. METHODS: A national online cross-sectional survey was conducted. Totally 20,786 physicians from 136 hospitals participated in the survey. Data were collected using an online self-reported questionnaire. Descriptive and logistic regression statistics were performed using the STATA software. RESULTS: The mean total sleep duration was 6.37 ± 0.87 h. Of all participants, 61.06% (n = 12,691) reported short sleep duration (less than 7 h per day). 46.97% (n = 9764) were not satisfied with their sleep. An older age and job-related factors (longer working hours per week, specialty including internal medicine, Ob/GYN and emergency medicine, working more night shifts, heavier workload, and working in East China) were significantly associated with reported short sleep duration. CONCLUSIONS: The majority of physicians in Chinese public hospitals experienced insufficient sleep duration. Changes are required to improve the wellbeing of physicians and patient outcomes.

Therapeutic targets and potential agents for the treatment of COVID-19.

The outbreak of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has become a global crisis. As of November 9, COVID-19 has already spread to more than 190 countries with 50,000,000 infections and 1,250,000 deaths. Effective therapeutics and drugs are in high demand. The structure of SARS-CoV-2 is highly conserved with those of SARS-CoV and Middle East respiratory syndrome-CoV. Enzymes, including RdRp, Mpro /3CLpro , and PLpro , which play important roles in viral transcription and replication, have been regarded as key targets for therapies against coronaviruses, including SARS-CoV-2. The identification of readily available drugs for repositioning in COVID-19 therapy is a relatively rapid approach for clinical treatment, and a series of approved or candidate drugs have been proven to be efficient against COVID-19 in preclinical or clinical studies. This review summarizes recent progress in the development of drugs against SARS-CoV-2 and the targets involved.

Rational Design of 2-Chloroadenine Derivatives as Highly Selective Phosphodiesterase 8A Inhibitors.

To validate the hypothesis that Tyr748 is a crucial residue to aid the discovery of highly selective phosphodiesterase 8A (PDE8A) inhibitors, we identified a series of 2-chloroadenine derivatives based on the hit clofarabine. Structure-based design targeting Tyr748 in PDE8 resulted in the lead compound 3a (IC50 = 0.010 µM) with high selectivity with a reasonable druglike profile. In the X-ray crystal structure, 3a bound to PDE8A with a different mode from 3-isobutyl-1-methylxanthine (a pan-PDE inhibitor) and gave a H-bond of 2.7 Å with Tyr748, which possibly interprets the 220-fold selectivity of 3a against PDE2A. Additionally, oral administration of compound 3a achieved remarkable therapeutic effects against vascular dementia (VaD), indicating that PDE8 inhibitors could serve as potential anti-VaD agents.