Structural basis of psychedelic LSD recognition at dopamine D1 receptor.

Understanding the kinetics of LSD in receptors and subsequent induced signaling is crucial for comprehending both the psychoactive and therapeutic effects of LSD. Despite extensive research on LSD's interactions with serotonin 2A and 2B receptors, its behavior on other targets, including dopamine receptors, has remained elusive. Here, we present cryo-EM structures of LSD/PF6142-bound dopamine D1 receptor (DRD1)-legobody complexes, accompanied by a ß-arrestin-mimicking nanobody, NBA3, shedding light on the determinants of G protein coupling versus ß-arrestin coupling. Structural analysis unveils a distinctive binding mode of LSD in DRD1, particularly with the ergoline moiety oriented toward TM4. Kinetic investigations uncover an exceptionally rapid dissociation rate of LSD in DRD1, attributed to the flexibility of extracellular loop 2 (ECL2). Moreover, G protein can stabilize ECL2 conformation, leading to a significant slowdown in ligand's dissociation rate. These findings establish a solid foundation for further exploration of G protein-coupled receptor (GPCR) dynamics and their relevance to signal transduction.

Discovery of LHQ490 as a highly selective fibroblast growth factor receptor 2 (FGFR2) inhibitor.

Fibroblast growth factor receptor 2 (FGFR2) represents an appealing therapeutic target for multiple cancers, yet no selective FGFR2 inhibitors have been approved for clinical use to date. Here, we report the discovery of a series of new selective, irreversible FGFR2 inhibitors. The representative compound LHQ490 potently inhibited FGFR2 kinase activity with an IC50 of 5.2 nM, and was >61-, >34-, and >293-fold selective against FGFR1, FGFR3, and FGFR4, respectively. LHQ490 also exhibited high selectivity in a panel of 416 kinases. Cell-based studies revealed that LHQ490 efficiently suppressed the proliferation of BaF3-FGFR2 cells with an IC50 value of 1.4 nM, and displayed >70- and >714-fold selectivity against BaF3-FGFR1 and the parental BaF3 cells, respectively. More importantly, LHQ490 potently suppressed the FGFR2 signaling pathways, selectively inhibited FGFR2-driven cancer cell proliferation, and induced apoptosis of FGFR2-driven cancer cells. Taken together, this study provides a potent and highly selective FGFR2 inhibitor for further development of FGFR2-targeted therapeutic agents.

2-Phenylcyclopropylmethylamine (PCPMA) as a privileged scaffold for central nervous system drug design.

The use of privileged scaffolds in medicinal chemistry is an effective way to accelerate the drug discovery process, especially at the hit/lead optimization stage. 2-Phenylcyclopropylmethylamine (PCPMA) is a less commonly used chemical scaffold in medicinal chemistry, but many PCPMA-containing compounds exert therapeutic effects for various diseases, in particular central nervous system (CNS) diseases such as depression, schizophrenia, sleep disorder, and Parkinson's disease. The backbone of the PCPMA scaffold enables a unique structure of an amino group linked to a benzene ring through an alkyl linker, making it a useful template for the design of bioactive compounds especially for CNS drug targets including aminergic GPCRs and transporters. This review summarizes the medicinal chemistry studies of PCPMA-containing drugs and drug-like molecules, their mechanisms of action, and biological activities. We conclude that PCPMA is a unique and useful privileged scaffold for CNS drug design.

The past, present, and future of ecogeographic isolation between closely related Aquilegia plants.

Quantifying the strength of the ecogeographic barrier is an important aspect of plant speciation research, and serves as a practical step to understanding the evolutionary trajectory of plants under climate change. Here, we quantified the extent of ecogeographic isolation in four closely related Aquilegia species that radiated in the Mountains of SW China and adjacent regions, often lacking intrinsic barriers. We used environmental niche models to predict past, present, and future species potential distributions and compared them to determine the degree of overlap and ecogeographic isolation. Our investigation found significant ecological differentiation in all studied species pairs except A. kansuensis and A. ecalacarata. The current strengths of ecogeographic isolation are above 0.5 in most cases. Compared with current climates, most species had an expanding range in the Last Glacial Maximum, the Mid Holocene, and under four future climate scenarios. Our results suggested that ecogeographic isolation contributes to the diversification and maintenance of Aquilegia species in the Mountains of northern and SW China and would act as an essential reproductive barrier in the future.

PHOSPHATE STARVATION RESPONSE1 (PHR1) interacts with JASMONATE ZIM-DOMAIN (JAZ) and MYC2 to modulate phosphate deficiency-induced jasmonate signaling in Arabidopsis.

Phosphorus (P) is a macronutrient necessary for plant growth and development. Inorganic phosphate (Pi) deficiency modulates the signaling pathway of the phytohormone jasmonate in Arabidopsis thaliana, but the underlying molecular mechanism currently remains elusive. Here, we confirmed that jasmonate signaling was enhanced under low Pi conditions, and the CORONATINE INSENSITIVE1 (COI1)-mediated pathway is critical for this process. A mechanistic investigation revealed that several JASMONATE ZIM-DOMAIN (JAZ) repressors physically interacted with the Pi signaling-related core transcription factors PHOSPHATE STARVATION RESPONSE1 (PHR1), PHR1-LIKE2 (PHL2), and PHL3. Phenotypic analyses showed that PHR1 and its homologs positively regulated jasmonate-induced anthocyanin accumulation and root growth inhibition. PHR1 stimulated the expression of several jasmonate-responsive genes, whereas JAZ proteins interfered with its transcriptional function. Furthermore, PHR1 physically associated with the basic helix-loop-helix (bHLH) transcription factors MYC2, MYC3, and MYC4. Genetic analyses and biochemical assays indicated that PHR1 and MYC2 synergistically increased the transcription of downstream jasmonate-responsive genes and enhanced the responses to jasmonate. Collectively, our study reveals the crucial regulatory roles of PHR1 in modulating jasmonate responses and provides a mechanistic understanding of how PHR1 functions together with JAZ and MYC2 to maintain the appropriate level of jasmonate signaling under conditions of Pi deficiency.

Molecular mechanism of phosphorous signaling inducing anthocyanin accumulation in Arabidopsis.

Anthocyanins, flavonoid compounds derived from secondary metabolic pathways, play important roles in various biological processes. Phosphorus (P) is an essential macroelement for plant growth and development, and P-starvation usually results in anthocyanin accumulation. However, the molecular mechanism of P deficiency promotes anthocyanin biosynthesis has not been well characterized. Here, we provided evidence that the P signaling core protein PHOSPHATE STARVATION RESPONSE1 (PHR1) is physically associate with transcription factors (TFs) involved in anthocyanidin biosynthesis, including PRODUCTION OF ANTHOCYANIN PIGMENTS1 (PAP1/MYB75), MYB DOMAIN PROTEIN 113 (MYB113) and TRANSPARENT TESTA 8 (TT8). PHR1 and its homologies positively regulated anthocyanin accumulation in Arabidopsis seedlings under P-deficient conditions. Disruption of PHR1 simultaneously rendered seedlings hyposensitive to limiting P, whereas the overexpression of PHR1 enhanced P- deficiency-induced anthocyanin accumulation. Genetic analysis demonstrated that 35S:PHR1-2HA-5 seedlings partially recovers the P deficiency insensitive phenotype of myb-RNAi and tt8 mutants. In summary, our study indicated that protein complexes formed by PHR1 and MBW complex directly mediate the process of P-deficiency-induced anthocyanin accumulation, providing a new mechanistic understanding of how P-deficient signaling depends on the endogenous anthocyanin synthesis pathway to promote anthocyanin accumulation in Arabidopsis.

A new approach to estimation of the proportional hazards model based on interval-censored data with missing covariates.

This paper discusses the fitting of the proportional hazards model to interval-censored failure time data with missing covariates. Many authors have discussed the problem when complete covariate information is available or the missing is completely at random. In contrast to this, we will focus on the situation where the missing is at random. For the problem, a sieve maximum likelihood estimation approach is proposed with the use of I-spline functions to approximate the unknown cumulative baseline hazard function in the model. For the implementation of the proposed method, we develop an EM algorithm based on a two-stage data augmentation. Furthermore, we show that the proposed estimators of regression parameters are consistent and asymptotically normal. The proposed approach is then applied to a set of the data concerning Alzheimer Disease that motivated this study.

Discovery of potential small molecular SARS-CoV-2 entry blockers targeting the spike protein.

An epidemic of pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading worldwide. SARS-CoV-2 relies on its spike protein to invade host cells by interacting with the human receptor protein Angiotensin-Converting Enzymes 2 (ACE2). Therefore, designing an antibody or small-molecular entry blockers is of great significance for virus prevention and treatment. This study identified five potential small molecular anti-virus blockers via targeting SARS-CoV-2 spike protein by combining in silico technologies with in vitro experimental methods. The five molecules were natural products that binding to the RBD domain of SARS-CoV-2 was qualitatively and quantitively validated by both native Mass Spectrometry (MS) and Surface Plasmon Resonance (SPR). Anti-viral activity assays showed that the optimal molecule, H69C2, had a strong binding affinity (dissociation constant KD) of 0.0947 µM and anti-virus IC50 of 85.75 µM.

Carboxyl Transfer of α-Keto Acids toward Oxazolidinones via Decarboxylation/Fixation of Liberated CO2.

A novel strategy for the direct carboxyl transfer involving a decarboxylative A3 reaction of α-keto acids, primary amines, and alkynes has been developed under a Cu(I)/Cu(II) binary catalysis system. This multicomponent reaction provides a facile and efficient approach for the production of a diverse range of 2-oxazolidinones in moderate to excellent yields through a one-pot CO2 elimination-fixation procedure. The conciseness of the "CO2 recycling" process makes this ideal synthesis superior over classical CO2 utilization.

Synthetic Access to Secondary Propargylamines via a Copper-Catalyzed Oxidative Deamination/Alkynylation Cascade.

A novel and selective cascade reaction of primary amines and alkynes for the synthesis of the corresponding secondary propargylamines is described. This protocol proceeds with a CuBr2/TBHP system through a process of oxidative deamination of primary amines to imine and alkynylation, featuring a wide scope of substrates with good functional-group tolerance and operational simplicity. Additionally, the use of two different primary amines could also work smoothly using this protocol.

Initiation Condition of Hemodialysis Is Independently Associated with All-Cause Mortality in Maintenance Hemodialysis Patients: A Retrospective Study.

BACKGROUND: Despite the progression of dialysis techniques,  the mortality of hemodialysis (HD) patients is still high in China. Here, a retrospective study was performed to investigate the neglected risk factors of all-cause mortality during maintenance HD (MHD). METHODS: We investigated 117 MHD patients who died between 2011 and 2016 in the Second Xiangya Hospital of Central South University HD center. In order to analyze the risk factors of 48 months all-cause death, the methods of Kaplan-Meier and Cox regression were used. RESULTS: Multivariate analyses of adjusted age and gender showed that MHD patients with estimated glomerular filtration rate <7 or >10 mL/min/1.73 m2 and anemia (hemoglobin <100 g/L) at the initiation of dialysis are independently associated with the higher death risk. Using central venous catheter vascular access, cerebrovascular comorbidities, diabetes, low-flux dialyzer, and dialysis frequency ≤2 times weekly were also the independent risk factors of death within 48 months. CONCLUSIONS: This study indicated that the status of HD initiation is a risk factor of long-term survival in MHD patients, which were usually ignored for lacking of nephrology care prior and could potentially be identified and modified to improve the survival prognosis. Video Journal Club "Cappuccino with Claudio Ronco" at  https://www.karger.com/Journal/ArticleNews/223997?sponsor=52.

The association between elevated serum uric acid levels and islet ß-cell function indexes in newly diagnosed type 2 diabetes mellitus: a cross-sectional study.

BACKGROUND: Serum uric acid (UA) has been reported as a risk factor for type 2 diabetes mellitus (T2DM). However, whether serum UA is associated with insulin resistance and insulin secretion, and the effect of gender on it in the case of the existed association, both remain undefined. METHODS: A cross-sectional study was designed and performed, which enrolled a total of 403 newly diagnosed T2DM patients (mean age, 50.21 ± 13.34 years (62.5% males)). Clinical characteristics and islet function indexes of all participants were analyzed based on gender-specific tertiles of serum UA levels. In addition, multiple linear regression analysis was conducted to investigate covariates associated with islet function indexes. RESULTS: The mean levels of serum UA were 331.05 µmol/L (interquartile range (IQR): 60.6, 400.9 µmol/L) and 267.9 µmol/L (IQR: 204.7, 331.9 µmol/L) in men and women, respectively. The values of insulin secretion indexes involving AUCins30/glu30, AUCins120/glu120 and total insulin disposition index (DI120) in females were significantly higher than those in males. Apart from the homeostasis model assessment insulin resistance of men, serum UA was positively associated with insulin secretion and insulin resistance indexes both in men and women. Multivariable linear regression analysis showed serum UA exerted an independent impact on insulin secretion in females, but not on insulin resistance. In males, islet function was simultaneously affected by serum UA age, body mass index (BMI), and serum lipids. CONCLUSION: Serum UA harbored a positive correlation with insulin secretion and insulin resistance indexes in newly diagnosed T2DM patients, which was influenced by gender, BMI, serum lipids. Hence, serum UA may be considered as a predictor for islet function in clinical practice.

Effects of RAAS Inhibitors in Patients with Kidney Disease.

Proteinuria and decline of renal function are associated with progression of kidney disease. The Renin Angiotensin Aldosterone System (RAAS) plays an important role in blood pressure regulation, fluid volume, and sodium balance. Overactivity of RAAS contributes to the pathogenesis of a variety of clinical conditions including progress of chronic kidney disease (CKD). This review summarizes the use of RAAS inhibitors as dual therapy or monotherapy in different stages of kidney disease. Experimental and clinical studies have demonstrated RAAS inhibitors prevent proteinuria, kidney fibrosis and slow decline of renal function and thus play a protective role in both early and end stages of kidney disease. While combination use of RAAS inhibitors showed higher efficiency compared with monotherapy, it is also associated with higher incidence of adverse events. Besides ACEI/ARBs, more mechanism research of mineralocorticoid receptor antagonists in kidney disease should be performed.

Serum D-dimer is a potential predictor for thromboembolism complications in patients with renal biopsy.

Renal biopsy has been widely recommended in clinic to determine the histological patterns of kidney disease. To prevent bleeding complications, patients should routinely stop anticoagulants prior to renal biopsy. However, patients with kidney disease are susceptible to thromboembolisms, particularly in those with severe hypoalbuminemia. This study was designed to investigate the application of serum D-dimer as a predictor for thrombotic events after renal biopsy. 400 consecutive native renal biopsies were prospectively included in this 2-month follow-up study. The overall incidence of bleeding and thrombotic complication is 4%, including hematuria or large perinephric hematoma (2.5%, n = 10) and thrombotic complication (1.5%, n = 6). Compared to low serum D-dimer (<2.00 µg/ml), subjects in the group of high serum D-dimer (≥2.00 µg/ml) were more incline to develop thrombotic complications (9.1% versus 0.3%; RR, 30.33; p < 0.001). D-dimer correlated positively with age (rs = 0.258, P < 0.001). Inverse correlations were found for albumin (rs = -0.339, P < 0.001). Taken together, patients with high serum D-dimer carry an increased risk of thrombotic complications after renal biopsy. Our findings suggest that serum D-dimer can serve as a potential predictor for thrombotic events in patients with kidney disease. Further cautions should be given to these subjects.

Tubular atrophy/interstitial fibrosis scores of Oxford classification combinded with proteinuria level at biopsy provides earlier risk prediction in lgA nephropathy.

The predictive effect of combining MEST with clinical data at biopsy on renal survival outcomes has not been investigated in patients with IgA nephropathy (IgAN). MEST of The Oxford classification of IgAN and 24-hour urine proteinuia measured at enrollment. The primary outcome was a composite of either ESRD (eGFR to <15 ml/min per 1.73 m2), or a permanent reduction in eGFR to below 50% of the value at biopsy. 742 patients were enrolled and follow-up >3 years, and were divided into two groups according to eGFR levels at biopsy. Multivariable logistical regression revealed that proteinuria at biopsy (OR 5.307 (95% Cl 3.003 to 9.376) p = 0.000), tubular atrophy/interstitial fibrosis scores (T) in MEST (OR 3.915 (95%Cl 2.710 to 5.654) p = 0.000) were the two predictors of eGFR decline for IgAN patients. Kaplan-Meier survival curves show significant difference in renal survival outcome among each T scores groups at biopsy (T0, T1, T2) (P < 0.05) and proteinuria levels at biopsy (P < 0.05), individially. Patients with T2 combined proteinuria at biopsy have the worst renal survival outcome. In conclusion, T scores in MEST classification combined with proteinuria at biopsy could be one of the important early predictors for the renal survial outcomes in patients with IgAN.

Rapamycin Enhances Repressed Autophagy and Attenuates Aggressive Progression in a Rat Model of IgA Nephropathy.

BACKGROUND: IgA nephropathy (IgAN) has been considered to be the most frequent form of primary glomerulonephritis that occurs worldwide with a variety of factors involved in its occurrence and development. The impact of autophagy in IgAN, however, remains partially unclear. This study was designed to investigate the effects of rapamycin in an IgAN model. METHOD: After establishing an IgAN rat model, SD rats were divided into 4 groups: control, control + rapamycin, IgAN, IgAN + rapamycin. Proteinuria and the pathological changes and the level of autophagy of kidney were texted. Identify the expression of phosphorylation and total mammalian target of rapamycin (mTOR) and s6k1 as well as cyclin D1 in the kidney of rats through Western blot and immunohistochemistry. RESULTS: With rapamycin treatment, we observed a significant reduction in the progression of proteinuria as well as alleviation of pathological lesions in IgAN rats. Besides, autophagy was inhibited, while the mTOR/S6k1 pathway was activated and expression of cyclin D1 was increased in IgAN. Rapamycin treatment increased autophagy and decreased the expression of cyclin D1. CONCLUSION: These results may suggest that mTOR-mediated autophagy inhibition may result in mesangial cell proliferation in IgAN.

A new framework of statistical inferences based on the valid joint sampling distribution of the observed counts in an incomplete contingency table.

Some existing confidence interval methods and hypothesis testing methods in the analysis of a contingency table with incomplete observations in both margins entirely depend on an underlying assumption that the sampling distribution of the observed counts is a product of independent multinomial/binomial distributions for complete and incomplete counts. However, it can be shown that this independency assumption is incorrect and can result in unreliable conclusions because of the under-estimation of the uncertainty. Therefore, the first objective of this paper is to derive the valid joint sampling distribution of the observed counts in a contingency table with incomplete observations in both margins. The second objective is to provide a new framework for analyzing incomplete contingency tables based on the derived joint sampling distribution of the observed counts by developing a Fisher scoring algorithm to calculate maximum likelihood estimates of parameters of interest, the bootstrap confidence interval methods, and the bootstrap testing hypothesis methods. We compare the differences between the valid sampling distribution and the sampling distribution under the independency assumption. Simulation studies showed that average/expected confidence-interval widths of parameters based on the sampling distribution under the independency assumption are shorter than those based on the new sampling distribution, yielding unrealistic results. A real data set is analyzed to illustrate the application of the new sampling distribution for incomplete contingency tables and the analysis results again confirm the conclusions obtained from the simulation studies.

Confidence intervals construction for difference of two means with incomplete correlated data.

BACKGROUND: Incomplete data often arise in various clinical trials such as crossover trials, equivalence trials, and pre and post-test comparative studies. Various methods have been developed to construct confidence interval (CI) of risk difference or risk ratio for incomplete paired binary data. But, there is little works done on incomplete continuous correlated data. To this end, this manuscript aims to develop several approaches to construct CI of the difference of two means for incomplete continuous correlated data. METHODS: Large sample method, hybrid method, simple Bootstrap-resampling method based on the maximum likelihood estimates (B 1) and Ekbohm's unbiased estimator (B 2), and percentile Bootstrap-resampling method based on the maximum likelihood estimates (B 3) and Ekbohm's unbiased estimator (B 4) are presented to construct CI of the difference of two means for incomplete continuous correlated data. Simulation studies are conducted to evaluate the performance of the proposed CIs in terms of empirical coverage probability, expected interval width, and mesial and distal non-coverage probabilities. RESULTS: Empirical results show that the Bootstrap-resampling-based CIs B 1, B 2, B 4 behave satisfactorily for small to moderate sample sizes in the sense that their coverage probabilities could be well controlled around the pre-specified nominal confidence level and the ratio of their mesial non-coverage probabilities to the non-coverage probabilities could be well controlled in the interval [0.4, 0.6]. CONCLUSIONS: If one would like a CI with the shortest interval width, the Bootstrap-resampling-based CIs B 1 is the optimal choice.

Confidence interval construction for the difference between two correlated proportions with missing observations.

Under the assumption of missing at random, eight confidence intervals (CIs) for the difference between two correlated proportions in the presence of incomplete paired binary data are constructed on the basis of the likelihood ratio statistic, the score statistic, the Wald-type statistic, the hybrid method incorporated with the Wilson score and Agresti-Coull (AC) intervals, and the Bootstrap-resampling method. Extensive simulation studies are conducted to evaluate the performance of the presented CIs in terms of coverage probability and expected interval width. Our empirical results evidence that the Wilson-score-based hybrid CI and the Wald-type CI together with the constrained maximum likelihood estimates perform well for small-to-moderate sample sizes in the sense that (i) their empirical coverage probabilities are quite close to the prespecified confidence level, (ii) their expected interval widths are shorter, and (iii) their ratios of the mesial non-coverage to non-coverage probabilities lie in interval [0.4, 0.6]. An example from a neurological study is used to illustrate the proposed methodologies.

Confidence-interval construction for rate ratio in matched-pair studies with incomplete data.

Matched-pair design is often used in clinical trials to increase the efficiency of establishing equivalence between two treatments with binary outcomes. In this article, we consider such a design based on rate ratio in the presence of incomplete data. The rate ratio is one of the most frequently used indices in comparing efficiency of two treatments in clinical trials. In this article, we propose 10 confidence-interval estimators for the rate ratio in incomplete matched-pair designs. A hybrid method that recovers variance estimates required for the rate ratio from the confidence limits for single proportions is proposed. It is noteworthy that confidence intervals based on this hybrid method have closed-form solution. The performance of the proposed confidence intervals is evaluated with respect to their exact coverage probability, expected confidence interval width, and distal and mesial noncoverage probability. The results show that the hybrid Agresti-Coull confidence interval based on Fieller's theorem performs satisfactorily for small to moderate sample sizes. Two real examples from clinical trials are used to illustrate the proposed confidence intervals.