Prevalence and incidence of skin tear in older adults：A systematic review and meta-analysis.

BACKGROUND: Skin tear (ST) is a public health problem in older adults; they substantially increase the risk of complications and cause serious adverse consequences and health care burden. AIM: To estimate the pooled prevalence and incidence of ST among older adults. METHODS: Ten databases were systematically searched from their inception to July 27, 2023. Two researchers performed a systematic review independently according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All inconsistencies were resolved by a principal researcher. The pooled prevalence and incidence of ST were estimated in R 4.3.1 program. RESULTS: Thirteen studies were included in this review. The pooled prevalence of ST was 6.0 % (95 % confidence interval (CI): 3.0%-11.0 %, I2 = 98 %), and the pooled incidence was 11.0 % (95 % CI: 5.0%-19.0 %, I2 = 94 %). The prevalence of ST was 11.0 % (95 % CI: 5.0%-19.0 %, I2 = 95 %) in long-term care facilities, 5.0 % (95 % CI: 3.0%-9.0 %, I2 = 86 %) in Europe, and 7.0 % (95 % CI: 1.0%-16.0 %, I2 = 82 %) in the Skin Tear Audit Research classification system (STAR). It has stabilized at 6.0 % since 2021. The incidence of ST was 15.0 % (95 % CI: 11.0%-20.0 %, I2 = 66 %) in long-term care facilities in Japan and 4.0 % (95 % CI: 2.0%-6.0 %) in Canada. CONCLUSIONS: Older adults are at a high risk for ST. Our findings emphasize the importance of epidemiologic studies and further exploring assessment tools for ST. Healthcare professionals should pay attention to ST, identify high-risk individuals and associated factors, and implement targeted prevention strategies for older adults.

Association between fear of falling and mortality in middle-aged and older adults: A systematic review and meta-analysis.

BACKGROUND: Fear of falling (FOF) has emerged as a significant public health issue, contributing to excess disability among middle-aged and older adults. The association between FOF and mortality remains unclear. METHODS: Prominent electronic databases (PubMed, Web of Science, the Cochrane Library, Embase, CINHAL, PsycINFO, Scopus, China National Knowledge Infrastructure, China Biology Medicine disc, and Wanfang Database) were searched from inception until October 21, 2023 (data updated on June 9, 2024), for cohort or longitudinal studies investigating the association between FOF and mortality. The heterogeneity between studies was quantitatively assessed using I2. A fixed-effect model calculated the pooled effect size. RESULTS: A total of seven cohort studies, including 27,714 participants, were analyzed in this systematic review and meta-analysis. The meta-analysis results demonstrated a positive association between FOF and mortality, with a significant increase in the risk of mortality for those with FOF (hazard ratio [HR]:1.29, 95 % confidence interval [CI]: 1.19-1.41, p < 0.05). Subgroup analysis indicated that age, male sex, clinical diagnosis of depression, number of chronic diseases, activity restriction due to FOF, and FOF levels were associated with mortality. CONCLUSIONS: FOF and mortality have a positive association, which needs to be confirmed by further prospective studies with large samples and long-term follow-up to provide evidence for clinicians to intervene in FOF to reduce mortality in middle-aged and older adults.

[Research Progress in the Role of the Ventral Tegmental Area-Medial Prefrontal Cortex Neural Circuit in the Regulation of Arousal].

There are mutual neural projections between the ventral tegmental area (VTA) and the medial prefrontal cortex (mPFC),which form a circuit.Recent studies have shown that this circuit is vital in regulating arousal from sleep and general anesthesia.This paper introduces the anatomical structures of VTA and mPFC and the roles of various neurons and projection pathways in the regulation of arousal,aiming to provide new ideas for further research on the mechanism of arousal from sleep and general anesthesia.

Click to Self-immolation: A "Click" Functionalization Strategy towards Triggerable Self-Immolative Homopolymers and Block Copolymers.

Self-immolative polymers (SIPs) are a class of degradable macromolecules that undergo stimuli-triggered head-to-tail depolymerization. However, a general approach to readily end-functionalize SIP precursors for programmed degradation remains elusive, restricting access to complex, functional SIP-based materials. Here we present a "click to self-immolation" strategy based on aroyl azide-capped SIP precursors, enabling the facile construction of diverse SIPs with different trigger units through a Curtius rearrangement and alcohol/thiol-isocyanate "click" reaction. This strategy is also applied to polymer-polymer coupling to access fully depolymerizable block copolymer amphiphiles, even combining different SIP backbones. Our results demonstrate that the depolymerization can be actuated efficiently under physiologically-relevant conditions by the removal of the trigger units and ensuing self-immolation of the p-aminobenzyl carbonate linkage, indicating promise for controlled release applications involving nanoparticles and hydrogels.

Self-Assembly of Rod-Coil Bottlebrush Copolymers into Degradable Nanodiscs with a UV-Triggered Self-Immolation Process.

Polymer nanodiscs, especially with stimuli-responsive features, represent an unexplored frontier in the nanomaterial landscape. Such 2D nanomaterials are considered highly promising for advanced biomedicine applications. Herein, we designed a rod-coil copolymer architecture based on an amphiphilic, tadpole-like bottlebrush copolymer, which can directly self-assemble into core-shell nanodiscs in an aqueous environment. As the bottlebrush side chains are made of amorphous, UV-responsive poly(ethyl glyoxylate) (PEtG) chains, they can undergo rapid end-to-end self-immolation upon light irradiation. This triggered nanodisc disassembly can be used to boost small molecule release from the nanodisc core, which is further aided by a morphological change from discs to spheres.

Seed color in lettuce is determined by the LsTT2, LsCHS, and Ls2OGD genes from the flavonoid biosynthesis pathway.

KEY MESSAGE: The mutated LsTT2 and Ls2OGD genes are responsible for white seeds and yellow seeds in lettuce, respectively. Three LsCHS genes are involved in the biosynthesis of flavonoid in seed coats. Lettuce seeds have several different colors, including black, yellow, and white. The genetic mechanisms underlying color variations of lettuce seeds remain unknown. We used genome-wide association studies (GWAS) and map-based cloning approaches to clone genes controlling the color of lettuce seeds. LsTT2, which encodes an R2R3-MYB transcription factor and is homologous to the TT2 gene in Arabidopsis, was shown to be the causal gene for the variation of black and white seeds in lettuce. A point mutation leads to the lack of stop codon in the LsTT2 transcript, resulting in white seeds. Knockout of the LsTT2 gene converted black seeds to white seeds. The locus controlling yellow seeds was mapped to Chromosome 2. Knockout of two 2-oxoglutarate-dependent dioxygenases (2OGD) genes from the candidate region converted black seeds to yellow seeds, suggesting that these two 2OGD proteins catalyze the conversion of yellow metabolites to black metabolites. We also showed that three LsCHS genes from the candidate region are associated with flavonoid biosynthesis in seeds. Knockout mutants of the three LsCHS genes decreased color intensity. This study provides new insights into the regulation of flavonoid biosynthesis in plants.

Genome-Wide Analysis of Barley bHLH Transcription Factors and the Functional Characterization of HvbHLH56 in Low Nitrogen Tolerance in Arabidopsis.

Improvement of low nitrogen (LN) tolerance or nitrogen use efficiency (NUE) in crops is imperative for environment-friendly agriculture development. The basic helix-loop-helix (bHLH) transcription factors are involved in multiple abiotic stresses and are suitable as candidate genes for improving LN tolerance. Few studies were performed on the characterization of the HvbHLH gene family and their function in response to LN stress in barley. In this study, 103 HvbHLH genes were identified through genome-wide analysis. HvbHLH proteins were classified into 20 subfamilies based on phylogenetic analysis in barley, which was supported by conserved motifs and gene structure analysis. The stress-related cis-element analysis in the promoters showed that HvbHLHs are probably involved in multiple stress responses. By phylogenetic analysis of HvbHLHs and bHLHs in other plants, some HvbHLHs were predicted to play roles in response to nutrition deficiency stress. Furthermore, at least 16 HvbHLHs were differentially expressed in two barley genotypes differing in LN tolerance under LN stress. Finally, overexpression of HvbHLH56 enhanced LN stress tolerance in transgenic Arabidopsis, suggesting it is an important regulator in LN stress response. The differentially expressed HvbHLHs identified herein may be valuable for the breeding of barley cultivars with LN tolerance.

DLGAP1-AS2 promotes estrogen receptor signalling and confers tamoxifen resistance in breast cancer.

BACKGROUND: Tamoxifen is a first-line endocrine agent and is often used to treat estrogen receptor-positive (ER+) breast cancer. Unfortunately, approximately 30-40% of patients who received tamoxifen therapy experience recurrence or progression to a fatal advanced stage due to tamoxifen resistance. However, the mechanisms of tamoxifen resistance remain unclear. METHODS: The expression of lncRNA DLGAP1 antisense RNA 2 (DLGAP1-AS2) was detected by qPCR. The effect of DLGAP1-AS2 on tamoxifen resistance was evaluated by MTT, colony formation, TUNEL and flow cytometric assays. The mechanisms by which DLGAP1-AS2 regulates tamoxifen resistance were investigated through qPCR, RNA pull-down assays and RNA immunoprecipitation (RIP) assays. RESULTS: Our results showed that DLGAP1-AS2 is significantly upregulated in breast cancer and that tamoxifen can induce DLGAP1-AS2 expression. Further investigation suggested that upregulation of DLGAP1-AS2 can increase cell viability and inhibit apoptosis, while downregulation of DLGAP1-AS2 results in the opposite effects. Mechanistically, DLGAP1-AS2 can bind to the AFF3 protein to inhibit its degradation, which further promotes ER signalling. CONCLUSIONS: Our research clarified that DLGAP1-AS2 promotes ER signalling to induce tamoxifen resistance and that targeting DLGAP1-AS2 might be a promising strategy to overcome tamoxifen resistance in breast cancer.

Metabolomics and Cytokine Analysis for Identification of Schizophrenia with Auditory Hallucination.

PURPOSE: To investigate the metabolic profile and biomarkers of schizophrenia with auditory hallucinations (AHs). METHODS: A total of 18 schizophrenic patients with the symptom of pure AHs (pAHs), 28 without AH (nAHs) and 43 age-matched healthy persons (Con) were enrolled in this study. Participants in pAHs and nAHs groups had relapsed into exacerbations of psychosis after self-discontinuing antipsychotics for at least one month; blood samples were drawn prior to restarting anti-psychotic treatment. Participants with history of recreational substance use were excluded. Positive and Negative Syndrome Scale (PANSS) and Auditory Hallucinations Rating Scale (AHRS) were used to assess the clinical mental state of all samples. Enzyme-linked immunosorbent assay (ELISA) was used to estimate the level of cytokines, and metabolomics analysis to identify potential biomarkers and pathways in the three groups. Graphpad 8.0 software was used to calculate the area under the receiver operating characteristic (ROC) curve. The relationship between metabolites and cytokines were determined using correlation analysis. RESULTS: Questionnaire scores showed significant differences in the positive symptom scale and PANSS total between nAHs and pAHs groups. Four cytokines (BDNF, IL-2, NGF-ß and TNF-α) differed significantly among the three groups. Six molecules in the nAHs group (phenylalanine, hippurate, serine, glutamate, valine and cystine) and four in the pAHs group (phenylalanine, serine, glutamate and cystine) were identified as potential biomarkers. In addition, phenylalanine was shown as a potential independent diagnostic biomarker for pAHs. Correlation analysis revealed that cystine and serine were significantly negatively correlated with IL-2 in the pAHs group. CONCLUSIONS: This study revealed the metabolic profile of patients with schizophrenia with AHs and provided new information to support the diagnosis. The identification of unique biomarkers would contribute to objective and reliable diagnoses of patients with schizophrenia with AH.

CircCD44 plays oncogenic roles in triple-negative breast cancer by modulating the miR-502-5p/KRAS and IGF2BP2/Myc axes.

BACKGROUND: Emerging studies have revealed the potent functions of circRNAs in breast cancer tumorigenesis. However, the biogenesis, biofunction and mechanism of circRNAs in triple-negative breast cancer (TNBC) are largely unknown. METHODS: High-throughput RNA sequencing was applied to identify dysregulated circRNAs in TNBCs and paired normal tissues. RNA pulldown and luciferase assays were performed to investigate the interaction between circular CD44 (circCD44, also annotated as hsa_circ_0021735) and miR-502-5p. RNA pulldown and RIP assays were used to investigate the interaction between circCD44 and IGF2BP2. Cell viability, colony formation, migration/invasion assays and in vivo tumorigenesis were used to investigate circCD44 biological functions. RESULTS: CircCD44 is an uncharacterized circRNA, which is highly expressed in TNBC, and its expression is negatively correlated with the prognosis of TNBC patients. CircCD44 promotes TNBC proliferation, migration, invasion and tumorigenesis at least partially by sponging miR-502-5p and interacting with IGF2BP2. CONCLUSION: Our data suggested that overexpressed circCD44 promotes TNBC progression. CircCD44 is potentially a novel diagnostic and therapeutic marker for TNBC patients.

Dopamine D1 Receptor in the Nucleus Accumbens Modulates the Emergence from Propofol Anesthesia in Rat.

It has been reported that systemic activation of D1 receptors promotes emergence from isoflurane-induced unconsciousness, suggesting that the central dopaminergic system is involved in the process of recovering from general anesthesia. The nucleus accumbens (NAc) contains abundant GABAergic medium spiny neurons (MSNs) expressing the D1 receptor (D1R), which plays a key role in sleep-wake behavior. However, the role of NAc D1 receptors in the process of emergence from general anesthesia has not been identified. Here, using real-time in vivo fiber photometry, we found that neuronal activity in the NAc was markedly disinhibited during recovery from propofol anesthesia. Subsequently, microinjection of a D1R selective agonist (chloro-APB hydrobromide) into the NAc notably reduced the time to emerge from propofol anesthesia with a decrease in δ-band power and an increase in ß-band power evident in the cortical electroencephalogram. These effects were prevented by pretreatment with a D1R antagonist (SCH-23390). Whole-cell patch clamp recordings were performed to further explore the cellular mechanism underlying the modulation of D1 receptors on MSNs under propofol anesthesia. Our data primarily demonstrated that propofol increased the frequency and prolonged the decay time of spontaneous inhibitory postsynaptic currents (sIPSCs) and miniature IPSCs (mIPSCs) of MSNs expressing D1 receptors. A D1R agonist attenuated the effect of propofol on the frequency of sIPSCs and mIPSCs, and the effects of the agonist were eliminated by preapplication of SCH-23390. Collectively, these results indicate that modulation of the D1 receptor on the activity of NAc MSNs is vital for emergence from propofol-induced unconsciousness.

ß-sitosterol ameliorates influenza A virus-induced proinflammatory response and acute lung injury in mice by disrupting the cross-talk between RIG-I and IFN/STAT signaling.

ß-Sitosterol (24-ethyl-5-cholestene-3-ol) is a common phytosterol Chinese medical plants that has been shown to possess antioxidant and anti-inflammatory activity. In this study we investigated the effects of ß-sitosterol on influenza virus-induced inflammation and acute lung injury and the molecular mechanisms. We demonstrate that ß-sitosterol (150-450 µg/mL) dose-dependently suppresses inflammatory response through NF-κB and p38 mitogen-activated protein kinase (MAPK) signaling in influenza A virus (IAV)-infected cells, which was accompanied by decreased induction of interferons (IFNs) (including Type I and III IFN). Furthermore, we revealed that the anti-inflammatory effect of ß-sitosterol resulted from its inhibitory effect on retinoic acid-inducible gene I (RIG-I) signaling, led to decreased STAT1 signaling, thus affecting the transcriptional activity of ISGF3 (interferon-stimulated gene factor 3) complexes and resulting in abrogation of the IAV-induced proinflammatory amplification effect in IFN-sensitized cells. Moreover, ß-sitosterol treatment attenuated RIG-I-mediated apoptotic injury of alveolar epithelial cells (AEC) via downregulation of pro-apoptotic factors. In a mouse model of influenza, pre-administration of ß-sitosterol (50, 200 mg·kg-1·d-1, i.g., for 2 days) dose-dependently ameliorated IAV-mediated recruitment of pathogenic cytotoxic T cells and immune dysregulation. In addition, pre-administration of ß-sitosterol protected mice from lethal IAV infection. Our data suggest that ß-sitosterol blocks the immune response mediated by RIG-I signaling and deleterious IFN production, providing a potential benefit for the treatment of influenza.

Tuning Ion Complexing To Rapidly Prepare Hollow Ag-Pt Nanowires with High Activity toward the Methanol Oxidization Reaction.

Hollow Pt-based nanowires (NWs) have important applications in catalysis. Their preparation often involves a two-step process in which M (M=Ag, Pd, Co, Ni) NWs are prepared and subsequently subjected to galvanic reaction in solution containing a Pt precursor. It is challenging to achieve a simple one-step preparation, because the redox potential of PtIV /Pt or PtII /Pt to Pt is high, and therefore, Pt atoms always form first. This work demonstrates that an appropriate pH can decrease the redox potential of PtIV /Pt and allows the one-step preparation of high-quality hollow Pt-Ag NWs rapidly (10 min). Moreover, it is easy to realize large-scale preparation with this method. The NW composition can be adjusted readily to optimize their performance in the electrocatalytic methanol oxidization reaction (MOR). Compared with commercial Pt/C, NWs with appropriate Ag/Pt ratios exhibit high stability, activity, and CO tolerance ability.

Synthesis and Self-Assembly of Bundle-Forming α-Helical Peptide-Dendron Hybrids.

Dendronized helix bundle assemblies combine the sequence diversity and folding properties of proteins with the tailored physical properties of dendrimers. Assembly of peptide-dendron hybrids into α-helical bundles encapsulates the helix bundle motif in a dendritic sheath that will allow the functional, protein-like domain to be transplanted to nonbiological environments. A bioorthogonal graft-to synthetic strategy for preparing helix bundle-forming peptide-dendron hybrids is described herein for hybrids 1a, 1b, and 2. Titration experiments monitored by circular dichroism spectroscopy support our self-assembly model for how the peptide-dendron hybrids self-assemble into α-helical bundles with the dendrons on outside of the bundle.

Serological positive markers of hepatitis B virus in femoral venous blood or umbilical cord blood should not be evidence of in-utero infection among neonates.

BACKGROUND: Maternal-infant transmission of hepatitis B virus(HBV) occurs even after passive-active immunization. Some scholars speculate that in-utero infection may be the main cause of immunoprophylaxis failure. However, there is a lack of evidence about the possible occurrence periods of perinatal transmission. METHODS: From 2008 to 2012, 428 pairs of HBsAg-positive mothers and neonates were enrolled and 385 infants aged 8-12 months were followed. HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc, HBV-DNA) were performed on all subjects. RESULTS: Of mothers who were positive for HBsAg, HBeAg, HBV-DNA, 35.1 %, 94.3 %, 12.7 % of their neonates were positive for those indices, respectively. Neonates' mean titers of those indices were significantly lower than their mothers'. There were no significant differences in rates of positivity and mean titers of anti-HBe and anti-HBc between neonates and mothers. Most of the positive indices turned negative during the follow-up period. Immunoprophylaxis failed in seventeen infants: four infants had HBV-DNA > 6 log 10copies/mL both at birth and in follow-up; in six infants, mean viral load was 3.72 ± 0.17 log 10copies/mLat birth and 7.62 ± 0.14 log 10copies/mL at follow-up; seven infants were HBV-DNA negative at birth but were found to have > 6 log 10copies/mL during follow-up. Infants that were immunoprophylaxis failures were all born to HBeAg-positive mothers with HBV-DNA > 6 log 10copies/mL. CONCLUSIONS: The placental barrier can partly prevent maternal HBsAg, HBeAg, HBV-DNA from passing through to fetus. Performing HBsAg, HBeAg, HBV-DNA once at birth can neither diagnose nor exclude maternal-infant transmission. The diagnosis of infection period depends on the dynamic changes in viral load from birth through the follow-up period but whether the infection occurred in utero, at delivery or during the neonatal period could not be determined.

Azide-rich peptides via an on-resin diazotransfer reaction.

Azide-containing amino acids are valuable building blocks in peptide chemistry, because azides are robust partners in several bioorthogonal reactions. Replacing polar amino acids with apolar, azide-containing amino acids in solid-phase peptide synthesis can be tricky, especially when multiple azide residues are to be introduced in the amino acid sequence. We present a strategy for effectively incorporating multiple azide-containing residues site-specifically.

Progress and Opportunities in Photocatalytic, Electrocatalytic, and Photoelectrocatalytic Production of Hydrogen Peroxide Coupled with Biomass Valorization.

Hydrogen peroxide (H2O2) has been considered an energy carrier (fuel) and oxidizer for various chemical synthesis and environmental remediation processes. Biomass valorization can generate high-value-added products in a green and pollution-free way to solve the energy and environmental crisis. The biomass valorization coupled with H2O2 generation via photo-, electro-, and photoelectrocatalysis plays a positive role in sustainable targets, which can maximize energy utilization and realize the production of value-added products and fuel synthesis. Recently, catalyst design and mechanism studies in H2O2 generation coupled with biomass valorization are in the infancy stage. Herein, this review begins with a background on photo-, electro-, and photoelectrocatalytic techniques for H2O2 generation, biomass valorization, and the H2O2 generation couples with biomass valorization. Meanwhile, the progress and reaction mechanism are reviewed. Finally, the prospects and challenges of a synergistic coupled system of H2O2 synthesis and value-added biomass in achieving high conversion, selectivity, and reaction efficiency are envisioned.

Haemoglobin, albumin, lymphocyte, and platelet score as an independent predictor for renal prognosis in IgA nephropathy.

Objective: The haemoglobin, albumin, lymphocyte, and platelet (HALP) score, a convenient and composite laboratory biomarker, can reflect inflammation and systemic nutritional status. This study was performed to investigate the effect of the HALP score on the prognosis of patients with IgA nephropathy (IgAN). Methods: This is a retrospective single centre study that enrolled 895 biopsy-confirmed IgAN patients from June 2019 to June 2022 who were followed for more than 1 year. Kaplan-Meier curves and Cox regression analyses were performed to determine the relationship between HALP and adverse outcomes. The restricted cubic splines was used to identify the possible associations. The optimal cut-off value of HALP for renal poor outcome was identified by the area under the receiver operating characteristic curve (AUC). Results: A total of 895 patients finally participated in the study and were divided into three groups (tertial 1-3) according to the baseline HALP score. More severe clinicopathologic features were observed in the lower HALP group, and Kaplan-Meier analysis showed patients in tertial 1 had a higher risk of kidney failure than the other groups (log-rank=11.02, P= 0.004). Multivariate Cox regression revealed that HALP score was an independent risk factor for renal prognosis in IgAN (adjusted HR: 0.967, 95% CI: 0.945-0.990, P = 0.006). The results of subgroup analysis suggested that HALP was more important in patients under the age of 50, BMI ≤ 23.9 and eGFR ≤ 90 mL/min/1.73 m2. The best cut-off HALP for renal survival was 38.83, sensitivity 72.1%, and specificity 55.9% (AUC: 0.662). Patients were further grouped according to HALP cut-off values and propensity matched. Multivariate Cox regression analysis revealed that HALP remained an independent predictor of IgAN in the matched cohort (HR 0.222, CI: 0.084-0.588, P=0.002). Conclusion: HALP is a novel and potent composite parameter to predict kidney outcome in patients with IgAN.

A glycoside hydrolase 30 protein BpXynC of Bacillus paralicheniformis NMSW12 recognized as A MAMP triggers plant immunity response.

Bacillus spp. has been widely used as a biocontrol agent to control plant diseases. However, little is known about mechanisms of the protein MAMP secreted by Bacillus spp. Herein, our study reported a glycoside hydrolase family 30 (GH30) protein, BpXynC, produced by the biocontrol bacteria Bacillus paralicheniformis NMSW12, that can induce cell death in several plant species. The results revealed that the recombinant protein triggers cell death in Nicotiana benthamiana in a BAK1-dependent manner and elicits an early defense response, including ROS burst, activation of MAPK cascades, and upregulation of plant immunity marker genes. BpXynC was also found to be a glucuronoxylanase that exhibits hydrolysis activity on xlyan. Two mutants of BpXynC which lost the glucuronoxylanase activity still retained the elicitor activity. The qRT-PCR results of defense-related genes showed that BpXynC induces plant immunity responses via an SA-mediated pathway. BpXynC and its mutants could induce resistance in N. benthamiana against infection by Sclerotinia sclerotiorum and tobacco mosaic virus (TMV). Furthermore, BpXynC-treated tomato fruits exhibited strong resistance to the infection of Phytophthora capsica. Overall, our study revealed that GH30 protein BpXynC can induce plant immunity response as MAMP, which can be further applied as a biopesticide to control plant diseases.

Molecular docking and MD simulation studies of 4-thiazol-N-(pyridin-2-yl)pyrimidin-2-amine derivatives as novel inhibitors targeted to CDK2/4/6.

PURPOSE: Nowadays, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have been approved for treating metastatic breast cancer and have achieved inspiring curative effects. But some discoveries have indicated that CDK 4/6 are not the requisite factors in some cell types because CDK2 partly compensates for the inhibition of CDK4/6. Thus, it is urgent to design CDK2/4/6 inhibitors for significantly enhancing their potency. This study aims to explore the mechanism of the binding of CDK2/4/6 kinases and their inhibitors to design novel CDK2/4/6 inhibitors for significantly enhancing their potency in different kinds of cancers. MATERIALS AND METHODS: A series of 72 disparately functionalized 4-substituted N-phenylpyrimidin-2-amine derivatives exhibiting potent inhibitor activities against CDK2, CDK4 and CDK6 were collected to apply to this research. The total set of these derivatives was divided into a training set (54 compounds) and a test set (18 compounds). The derivatives were constructed through the sketch molecule module in SYBYL 6.9 software. A Powell gradient algorithm and Tripos force field were used to calculate the minimal structural energy and the minimized structure was used as the initial conformation for molecular docking. By the means of 3D-QSAR models, partial least squares (PLS) analysis, molecular dynamics (MD) simulations and binding free energy calculations, we can find the relationship between structure and biological activity. RESULTS: In this study, we used molecular docking, 3D-QSAR and molecular dynamics simulation methods to comprehensively analyze the interaction and structure-activity relationships of 72 new CDK2/4/6 inhibitors. We used detailed statistical data to reasonably verify the constructed 3D-QSAR models for three receptors (q2 of CDK2 = 0.714, R2pred = 0.764, q2 = 0.815; R2pred of CDK4 = 0.681, q2 = 0.757; R2pred of CDK6 = 0.674). MD simulations and decomposition energy analysis validated the reasonability of the docking results and identified polar interactions as crucial factors that influence the different bioactivities of the studied inhibitors of CDK2/4/6 receptors, especially the electrostatic interactions of Lys33/35/43 and Asp145/158/163. The nonpolar interaction with Ile10/12/19 was also critical for the differing potencies of the CDK2/4/6 inhibitors. We concluded that the following probably enhanced the bioactivity against CDK2/4/6 kinases: (1) electronegative groups at the N1-position and electropositive and moderate-sized groups at ring E; (2) electrogroups featured at R2; (3) carbon atoms at the X-position or ring C replaced by a benzene ring; and (4) an electrogroup as R4. CONCLUSION: Previous studies, to our knowledge, only utilized a single approach of 3D-QSAR and did not integrate this method with other sophisticated techniques such as molecular dynamics simulations to discover new potential inhibitors of CDK2, CDK4, or CDK6. So we applied the intergenerational technology, such as 3D-QSAR technology, molecular docking simulation techniques, molecular dynamics simulations and MMPBSA19/MMGBSA20-binding free energy calculations to statistically explore the correlations between the structure with biological activities. The constructed 3D-QSAR models of the three receptors were reasonable and confirmed by the excellent statistical data. We hope the results obtained from this work will provide some useful references for the development of novel CDK2/4/6 inhibitors.