Dibenzofurans from nature: Biosynthesis, structural diversity, sources, and bioactivities.

Dibenzofurans are a small class of natural products with versatile biological activities that used to be thought to come mainly from lichens and ascomycetes. In fact, they are also distributed widely in higher plants, especially in the families Rosaceae and Myrtaceae. Dibenzofurans and derivatives from lichens and ascomycetes have been well reviewed, but dibenzofurans from all biological sources in nature have not been reviewed. In this review, dibenzofurans from all natural sources have been comprehensively reviewed, and a total of 211 dibenzofurans isolated and identified from organisms between 1843 and March 2023 are categorized and discussed, including their biosynthesis, structural diversity, sources, and bioactivities.

Optimum Doses and Forms of Selenium Maintaining Reproductive Health via Regulating Homeostasis of Gut Microbiota and Testicular Redox, Inflammation, Cell Proliferation, and Apoptosis in Roosters.

BACKGROUND: There is a U-shaped relationship between dietary selenium (Se) ingestion and optimal sperm quality. OBJECTIVES: This study aimed to investigate the optimal dietary dose and forms of Se for sperm quality of breeder roosters and the relevant mechanisms. METHODS: In experiment 1, 18-wk-old Jingbai laying breeder roosters were fed a Se-deficient base diet (BD, 0.06 mg Se/kg), or the BD + 0.1, 0.2, 0.3, 0.4, 0.5, or 1.0 mg Se/kg for 9 wk. In experiment 2, the roosters were fed the BD or the BD + sodium selenite (SeNa), seleno-yeast (SeY), or Se-nanoparticles (SeNPs) at 0.2 mg Se/kg for 9 wk. RESULTS: In experiment 1, added dietary 0.2 and 0.3 mg Se/kg led to higher sperm motility and lower sperm mortality than the other groups at weeks 5, 7, and/or 9. Furthermore, added dietary 0.2-0.4 mg Se/kg produced better testicular histology and/or lower testicular 8-hydroxy-deoxyguanosine than the other groups. Moreover, integrated testicular transcriptomic and cecal microbiomic analysis revealed that inflammation, cell proliferation, and apoptosis-related genes and bacteria were dysregulated by Se deficiency or excess. In experiment 2, compared with SeNa, SeNPs slightly increased sperm motility throughout the experiment, whereas SeNPs slightly reduced sperm mortality compared with SeY at week 9. Both SeY and SeNPs decreased malondialdehyde in the serum than those of SeNa, and SeNPs led to higher glutathione peroxidase (GPX) and thioredoxin reductase activities and GPX1 and B-cell lymphoma 2 protein concentrations in the testis compared with SeY and SeNa. CONCLUSIONS: The optimal dietary Se dose for reproductive health of breeder roosters is 0.25-0.35 mg Se/kg, and SeNPs displayed better effects on reproductive health than SeNa and SeY in laying breeder roosters. The optimal doses and forms of Se maintain reproductive health of roosters associated with regulation intestinal microbiota homeostasis and/or testicular redox balance, inflammation, cell proliferation, and apoptosis.

Progress of KRAS G12C mutations in non-small cell lung cancer / 国际肿瘤学杂志

With the continuous in-depth research on the mechanism of KRAS G12C mutations in targeted therapy of non-small cell lung cancer, KRAS G12C has evolved from non producible to an important targeted therapy site. The KRAS G12C mutation inhibitor has achieved dual progress in efficiency and survival in targeted therapy of non-small cell lung cancer. Although drug resistance is inevitable with treatment, research on drug resistance mechanisms has found that combination medication is one of the ways to overcome or reduce drug resistance.

The predictive value of sarcopenia index for postoperative pneumonia in ≥70 years old patients of esophageal cancer / 中华老年医学杂志

Objective:To investigate the clinical application value of commonly used preoperative indicators of sarcopenia in predicting postoperative pneumonia in patients aged 70 years and above with esophageal cancer.Methods:A retrospective analysis was conducted on the clinical data of 398 elderly patients(≥70 years old)with esophageal squamous cell carcinoma who underwent thoracic laparoscopic radical resection of esophageal cancer in our hospital from January 2020 to December 2021.The study aimed to investigate the correlation between clinical pathological indicators and commonly used measurement indicators of sarcopenia and postoperative pneumonia.Statistical analysis was performed to analyze the data.Results:The study found that the proportion of postoperative pneumonia in esophageal squamous cell carcinoma patients aged 70 years and above was 27.9%(111 out of 398). The pneumonia group had significantly lower preoperative BMI and peak expiratory flow(PEF)measurements compared to the non-pneumonia group, with statistically significant differences( t=2.799, 2.674, both P<0.05). Logistic multivariate analysis revealed that low PEF, low psoas major muscle index(PMI), and low psoas muscle density(PMD)were the primary risk factors for postoperative pneumonia in esophageal cancer patients aged 70 years and above(Wald χ2 values were 7.577, 6.091, 6.845, all P<0.05). The risk of postoperative pneumonia in esophageal cancer patients aged 70 years and above with low PEF, low PMI, and low PMD was found to be 1.969 times higher(95% CI: 1.215-3.185, P=0.006), 1.912 times higher(95% CI: 1.143-3.205, P=0.014), and 1.832 times higher(95% CI: 1.164-2.882, P=0.009)respectively, compared to patients with high PEF, high PMI, and high PMD. Conclusions:Low PEF, low PMI, and low PMD are significant risk factors for postoperative pneumonia in esophageal cancer patients aged 70 years and older.Preoperative PEF, PMI, and PMD, which are commonly utilized measurement indicators for sarcopenia, can be utilized as early screening indicators for postoperative pneumonia.

Endovascular therapy combined with laparoscopic surgery for acute mesentery artery occlusion / 中华普通外科杂志

Objective:To explore the efficacy and safety of endovascular intervention combined with preoperative laparoscopic exploration in the treatment of patients with acute mesenteric artery ischemia.Methods:This was a prospective cohort study (NCT04686981). The study enrolled 31 patients with acute mesenteric artery ischemia from Oct 1, 2020 to Oct 1, 2022. Among them, 26 patients (84%) were male, with a mean age of (67±13) years and a mean time to onset of (21±8) hours. All patients underwent laparoscopic exploration in the hybrid operating room. If the presence of intestinal necrosis or suspected necrosis was clearly determined, the patient would undergo open surgery (mesenteric artery embolization, intestinal resection and intestinal double stoma) as the treatment by gastrointestinal surgeon. If intestinal necrosis or suspected necrosis was not found by laparoscopy, the patient would undergo endovascular intervention by vascular surgeon. The primary observational endpoints of this study were the proportion of patients who were not dependent on total parenteral nutrition and all-cause mortality within 30 days after operation. The secondary observational endpoints were the rate of mesenteric vascular patency within 30 days and the proportion of interventions that were converted to open surgery.Results:Six patients underwent open surgery and 25 patients underwent endovascular intervention, including 13 cases of thrombus reduction alone, 3 cases of stent implantation during the same period after reduction, and 9 cases of stent implantation alone. Twenty-four patients (77%) were completely weaned from the TPN within 30 days after the procedure, and all-cause mortality was observed in 3 cases (9.7%). The patency rate of the mesenteric artery within 30 days after the procedure was 82.1%. The rate of conversion to open surgery after intervention was 16%.Conclusions:Endovascular intervention combined with preoperative laparoscopic exploration can clarify intestinal ischemia in acute mesenteric patients as early as possible, and individualized treatment strategies for each patient by multidisciplinary care team can potentially improve the prognosis of such patients.

Specific PCR for Identification of Astragalus membranaceus var. mongholicus Seeds， A. membranaceus Seeds， and Adulterants / 中国实验方剂学杂志

ObjectiveTo establish a method based on specific polymerase chain reaction （PCR） that can accurately and rapidly identify Astragalus membranaceus var. mongholicus （AMM） seeds and A. membranaceus （AM） seeds. MethodThe Chloroplast Genome Information Resource （CGIR） and IdenDSS were used to obtain the characteristic DNA fragments of AMM and AM， and the specific single nucleotide polymorphism （SNP） sites of AMM and AM were screened out， on the basis of which the specific primers MG-F/MG-R of AMM and MJ-F/MJ-R of AM were designed. The specific PCR method for identifying AMM and AM was established and optimized， and the specificity and applicability of the method were investigated. ResultThe specific PCR conditions for the identification of AMM were primers MG-F/MG-R， annealing at 62 ℃， and 28 cycles. After PCR amplification and gel electrophoresis， the specific band appeared at about 220 bp， with no band for the seeds of AM or adulterants. The specific PCR conditions for identifying the AM were primers MJ-F/MJ-R， annealing at 58 ℃， and 28 cycles. After PCR amplification and gel electrophoresis， the band appeared at about 150 bp， with no band of AMM or adulterants. ConclusionThe specific PCR method established in this study can accurately and quickly identify the seeds of AMM and AM， which provides a basis for the classification and accurate identification of Astragalus seeds and adulterants.

Identification of Original Plants of Lycii Cortex by Multiplex Allele-specific PCR / 中国实验方剂学杂志

ObjectiveTo identify Lycium chinense and L. barbarum as the original plants of Lycii Cortex simply and efficiently by multiple allele-specific polymerase chain reaction （PCR）. MethodThe chloroplast genome sequences of L. chinense and L. barbarum were downloaded from the Chloroplast Genome Information Resource （CGIR）， and then IdenDSS was employed to screen out the specific single nucleotide polymorphism （SNP） sites between the two plants. Primer 5.0 was used to design the specific primers， including primers GQ-F/R for identifying L. chinense and primers NX-F/R for identifying L. barbarum. Furthermore， the primer concentration ratio， annealing temperature， cycles， and Taq enzyme were optimized to establish the optimal PCR system and conditions for plant identification. Finally， the applicability of the established method was examined with the plant samples collected from different regions. ResultThe PCR with GQ-F/R∶NX-F/R concentration ratio of 2∶1 at the annealing temperature at 59 ℃ and for 30 cycles showed specific bands at 183 bp and 295 bp， respectively， for L. chinense and L. barbarum samples from different regions. ConclusionThe established PCR approach can simply， rapidly， and efficiently identify the original plants of Lycii Cortex， serving as a new method for the discrimination between L. chinense and L. barbarum. Moreover， the method provides technical support for the research and development of classic famous prescriptions containing Lycii Cortex.

PCR-RFLP for Distinguishing Periplocae Cortex from Acanthopanacis Cortex and Lycii Cortex / 中国实验方剂学杂志

ObjectiveTo establish a polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method for rapid distinguishing Periplocae Cortex from Acanthopanacis Cortex and Lycii Cortex， so as to avoid the influence of genetic confusion on drug safety. MethodThe DSS-tagged sequences of Periplocae Cortex were obtained from the Chloroplast Genome Information Resource （CGIR） and analyzed to find the enzymatic cleavage sites that were different from those of Acanthopanacis Cortex and Lycii Cortex. The specific enzymatic cleavage site， Cla I， of Periplocae Cortex was selected， on the basis of which the primers for PCR-RFLP were designed. Furthermore， the factors such as annealing temperature， number of cycles， Taq enzyme， PCR instruments， and enzymatic treatment time that may influence PCR-RFLP were studied. The established PCR-RFLP method was applied to the identification of Periplocae Cortex， Acanthopanacis Cortex， and Lycii Cortex samples produced in different regions. ResultThe PCR-RFLP at the annealing temperature of 59 ℃ and with 40 cycles showed clear bands of the samples. When the enzyme digestion time was 30 min. The reaction produced the target bands at about 140 bp and 290 bp for both Periplocae Cortex and its original plant and only a band at about 430 bp for Acanthopanacis Cortex， Lycii Cortex， and their original plants. The method can accurately distinguish Periplocae Cortex from its confounders Acanthopanacis Cortex and Lycii Cortex. ConclusionThe PCR-RFLP method for distinguishing Periplocae Cortex from Acanthopanacis Cortex and Lycii Cortex was established. It has high stability， sensitivity， and applicability， providing a reference for the quality control of Periplocae Cortex， Acanthopanacis Cortex， and Lycii Cortex.

Identification of Scolopendra Dispensing Granules by Allele-specific PCR / 中国实验方剂学杂志

ObjectiveTo establish an allele-specific polymerase chain reaction （PCR） method for identifying Scolopendra dispensing granules， so as to ensure the quality and therapeutic effects of Scolopendra and its preparations. MethodThe primer interval suitable for the PCR was selected based on the cytochrome c oxidase subunit 3（COX-3） gene sequence of Scolopendra， and the single nucleotide polymorphism （SNP） loci of Scolopendra and its adulterants were mined from the interval for the design of specific primers. The samples of Scolopendra and its adulterants were collected. The PCR system was established and optimized regarding the annealing temperature， cycles， Taq enzymes， DNA template amount， PCR instruments， and primer concentrations， and the specificity and applicability of this method were evaluated. ResultThe PCR system was composed of 12.5 μL 2×M5 PCR Mix， 0.4 μL forward primer （10 μmol·L-1）， 0.4 μL reverse primer （10 μmol·L-1）， 2.5 μL DNA template， and 9.2 μL sterile double distilled water. PCR parameters： Pre-denaturation at 94 ℃ for 3 min， 30 cycles （94 ℃ for 20 s， 62 ℃ for 20 s， 72 ℃ for 45 s）， and extension at 72 ℃ for 5 min. After PCR amplification with the system and parameters above， the electrophoresis revealed a bright band at about 135 bp for Scolopendra and no band for the adulterants. ConclusionThe established allele-specific PCR method can accurately identify the medicinal materials， decoction pieces， and standard decoction freeze-dried powder of Scolopendra， as well as the intermediates and final products of Scolopendra dispensing granules， which is of great significance for ensuring the quality and clinical efficacy of Scolopendra and its preparations.

Crystal structure of phloridzin and its distribution changes in flowering and fruiting stage of Malus rockii.

The exact structure of phloridzin was further confirmed as phloretin 6'-O-glucopyranoside by a single-crystal X-ray diffraction experiment. The distribution changes of phloridzin in flowering, fruitlet, and fruit ripening phases of Malus rockii were quantified by an HPLC with an external standard. The concentrations of phloridzin in leaves, twigs, and bark and xylem of twigs increased at first and then decreased, and reached the highest value in the fruitlet period. The highest concentration of phloridzin was found in leaves, with the percentage contents of 10.92-14.43 %. What is more, the decreased value of the concentration of phloridzin in leaves from fruit ripening period was almost equivalent to the increased value of the concentration of phloretin. This interesting physiological phenomenon should be able to provide the readers, especially plant physiologists, with a new perspective for the development and utilization of phloridzin.

Reconsidering the Structures of C2 Al4 - and C2 Al5.

The study of C2 Al4 -/0 and C2 Al5 -/0 was conducted using anion photoelectron spectroscopy and quantum chemical computations. The present findings reveal that C2 Al4 - has a boat-like structure, with a single C2 unit surrounded by four aluminum atoms. In contrast, the neutral C2 Al4 species adopts a D2h planar structure with two planar tetracoordinate carbon (ptC) units, consistent with previous reports. Furthermore, the global minimum isomer of C2 Al5 - adopts a D3h symmetry, where the C2 unit interacts with five aluminum atoms. It was also found that a lower symmetry structure of C2 Al5 - , where all five aluminum atoms are located on the same side of the C2 unit, albeit slightly higher in energy compared to the D3h structure. These computations show that the D3h structure of C2 Al5 - is highly stable, exhibiting a large HOMO-LUMO gap.

Diversified cassane family diterpenoids from the leaves of Caesalpinia minax exerting anti-neuroinflammatory activity through suppressing MAPK and NF-κB pathways in BV-2 microglia.

ETHNOPHARMACOLOGICAL RELEVANCE: Caesalpinia minax Hance, whose seeds are known as "Ku-shi-lian" in China, have been used in Chinese folk medicine for treatment of rheumatism, dysentery, and skin itching. However, the anti-neuroinflammatory constituents of its leaves and their mechanism are rarely reported. AIM OF THE STUDY: To search for new anti-neuro-inflammatory compounds from the leaves of C. minax and elucidate their mechanism on anti-neuroinflammatory effect. MATERIALS AND METHODS: The main metabolites of the ethyl acetate fraction from C. minax were analyzed and purified via HPLC and various column chromatography techniques. Their structures were elucidated on the basis of 1D and 2D NMR, HR-ESI-MS, and single crystal X-ray diffraction analysis. Anti-neuroinflammatory activity was evaluated in BV-2 microglia cells induced by LPS. The expression levels of molecules in NF-κB and MAPK signaling pathways were analyzed through western blotting. Meanwhile, the time- and dose-dependent expression of associated proteins such as iNOS and COX-2 were detected by western blotting. Furthermore, Compounds 1 and 3 were performed on the NF-κB p65 active site using molecular docking simulation to elucidate the molecular level inhibition mechanism. RESULTS: 20 cassane diterpenoids, including two novel ones (caeminaxins A and B) were isolated from the leaves of C. minax Hance. Caeminaxins A and B possessed a rare unsaturated carbonyl moiety in their structures. Most of the metabolites exhibited potent inhibition effects with IC50 values ranging from 10.86 ± 0.82 to 32.55 ± 0.47 µM. Among them, caeminaxin A inhibited seriously the expression of iNOS and COX-2 proteins and restrained the phosphorylation of MAPK and the activation of NF-κB signaling pathways in BV-2 cells. The anti-neuro-inflammatory mechanism of caeminaxin A has been studied systematically for the first time. Furthermore, biosynthesis pathways for compounds 1-20 were discussed. CONCLUSIONS: The new cassane diterpenoid, caeminaxin A, alleviated the expression of iNOS and COX-2 protein and down-regulated of intracellular MAPK and NF-κB signaling pathways. The results implied that cassane diterpenoids had potential to be developed into therapeutic agents for neurodegenerative disorders such as Alzheimer's disease.

CCL2 is required for initiation but not persistence of HIV infection mediated neurocognitive disease in mice.

HIV enters the brain within days of infection causing neurocognitive impairment (NCI) in up to half of infected people despite suppressive antiretroviral therapy. The virus is believed to enter the brain in infected monocytes through chemotaxis to the major monocyte chemokine, CCL2, but the roles of CCL2 in established NCI are not fully defined. We addressed this question during infection of conventional and CCL2 knockout mice with EcoHIV in which NCI can be verified in behavioral tests. EcoHIV enters mouse brain within 5 days of infection, but NCI develops gradually with established cognitive disease starting 25 days after infection. CCL2 knockout mice infected by intraperitoneal injection of virus failed to develop brain infection and NCI. However, when EcoHIV was directly injected into the brain, CCL2 knockout mice developed NCI. Knockout of CCL2 or its principal receptor, CCR2, slightly reduced macrophage infection in culture. Treatment of mice prior to and during EcoHIV infection with the CCL2 transcriptional inhibitor, bindarit, prevented brain infection and NCI and reduced macrophage infection. In contrast, bindarit treatment of mice 4 weeks after infection affected neither brain virus burden nor NCI. Based on these findings we propose that HIV enters the brain mainly through infected monocytes but that resident brain cells are sufficient to maintain NCI. These findings suggest that NCI therapy must act within the brain.

Discovery of diversified cassane diterpenoids as potent antibacterial agents from Caesaplinia pulcherrima and their mechanisms.

BACKGROUND: Natural products play a significant role in the development of novel bactericide candidates. Caesalpinia pulcherrima, a traditional medicine, had anti-inflammatory, antimicrobial, and antifeedant activities, therefore the previous bioassay results of C. pulcherrima implied that its main active ingredients may have potential to be used as botanical bactericides. RESULTS: Bio-guided isolation of C. pulcherrima was conducted to obtain 11 novel cassane diterpenoids (capulchemins A-K) and 10 known sesquiterpenes. Their structures were established by extensive spectroscopic methods and single-crystal X-ray diffraction analyses. Capulchemins A-F possess a rare aromatic C ring, while capulchemin K with a 15,16-degradative carbon skeleton represents a rare group of cassane diterpenes. Capulchemin A exhibited remarkable antibacterial activity against four phytopathogenic bacteria, particularly against Pseudomonas syringae pv. actinidae and Bacillus cereus, with minimal inhibitory concentration values of 3.13 µM. Meanwhile, capulchemin A showed significant control effect on kiwifruit canker in vivo. Further investigation of its mechanism of antibacterial activity revealed that compound 1 was closely related to destroy cell membrane to cause cell death. Additionally, some of those cassane diterpenoids showed potential antifeedant against Mythimna separate walker and Plutella xylostella. Consequently, capulchemin A could have the potential to be used as a template for the development for new eco-friendly NP-based bactericides. CONCLUSION: These data contribute to a better understanding of the antibacterial activity of cassane diterpenes. Cassane diterpenes have been discovered to be leading to broad application prospects in the development as novel botanical bactericides. © 2023 Society of Chemical Industry.

Farnesane sesquiterpenoids from Rubus delavayi and their anti-Trichinella spiralis activities.

Two new farnesane sesquiterpenoid glycosides, rubusdelosides A and B (1 and 4), together with five known farnesane sesquiterpenoids (2, 3, and 5-7), and two known meroterpenoids (8 and 9), were isolated from water extract of the herbs of R. delavayi. Their structures were identified by the comprehensive analyses of physicochemical properties and spectroscopic data (NMR and HR-ESI-MS). Compounds 1-8 showed moderate in vivo anti-T. spiralis activities.

Flavonoids from Scutellaria likiangensis Diels and their antimalarial activities.

Two new flavonoid glycosides scutelikiosides A and B (13 and 23), along with twenty-one known compounds from the 75% ethanol extract of roots of Scutellaria likiangensis Diels. Their structures were determined by the comprehensive analyses of the spectroscopic data (1D NMR, 2D NMR, HRESIMS, and CD) and physicochemical properties. Compounds 4-14, 17-19, 21, and 22 were evaluated for their in vivo antimalarial activities against Plasmodium yoelii BY265RFP in mice. Compound 17 exhibited significant activity close to artemisinin with an inhibition ratio of 29.2%, and compounds 6, 9-12, 14, 18, 19, and 22 exhibited moderate antimalarial activities with inhibition ratios ranging from 10.2% to 20.0% at a dose of 25 mg/kg/day. In addition, a summary of preliminary structure-activity relationship of isolated flavonoids for in vivo antimalarial activity was described.

Four new phenolic glycosides from Dobinea delavayi.

Three new benzophenone glycosides, 2-O-ß-D-glucopyranosyl-6,3',4'-trihydroxy-4-methoxybenzophenone (1), 4'-O-ß-D-glucopyranosyl-2,4,6,3'-tetramethoxybenzophenone (2) and 2-O-ß-D-glucopyranosyl-4'-hydroxy-6-methylbenzophenone (3), and a new flavonoid glycoside 5'-hydroxyombuoside (6), along with three known phenolic glycosides 4-O-ß-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone (4), mangiferin (5), and ombuoside (7), were isolated from the 80% ethanol extract of roots of Dobinea delavayi. Their structures were determined by the comprehensive analyses of the physicochemical properties and spectroscopic data (1D NMR, 2D NMR, and HR-ESI-MS). Cytotoxicity and in vitro antimalarial activity of compounds 1, 3, 4, 6, and 7 were evaluated by MTT colorimetric assay and ß-hematin formation inhibition assay, respectively.

Association between atrial fibrillation reoccurrence and new-onset ischemic stroke among patients with nonvalvular atrial fibrillation / 中华心血管病杂志

Objective: Explore the association between atrial fibrillation (AF) reoccurrence and new-onset ischemic stroke (IS) in patients with nonvalvular AF, and explore whether there is a high-risk period of IS after recurrent episodes of AF. Methods: A nested case-control study design was used. A total of 565 nonvalvular AF patients with new-onset IS after a follow-up of at least 2 years in the China-AF cohort were enrolled as the case group, and 1 693 nonvalvular AF patients without new-onset IS were matched as the control group at a ratio of 1∶3. Frequency and types of recurrent AF in the previous 1 or 2 years were compared between two groups, and the adjusted associations of AF reoccurrence with new onset IS were explored using conditional logistic regression analysis. The proportion of recurrent AF was compared between the case period and control period, and conditional logistic regression analysis was performed to calculate adjusted associations of case-period AF with IS. Results: The nested case-control study design results showed that the proportion of at least one record of recurrent AF in the previous 1 year was higher in the case group than in the control group (72.0% vs. 60.8%, P<0.05), and the recurrent AF was positively correlated with new-onset IS (adjusted OR=1.80, P<0.001). Similar results were also observed in the previous 2 years period. The case-crossover study design analysis showed that among 565 patients with new-onset IS, recurrent AF in the case period was positively correlated with IS (adjusted OR=1.61, P=0.003). Conclusion: Recurrent AF is associated with IS, and there may be a high-risk period of IS after recurrent episodes of AF.

Association between atrial fibrillation reoccurrence and new-onset ischemic stroke among patients with nonvalvular atrial fibrillation / 中华心血管病杂志

Objective: Explore the association between atrial fibrillation (AF) reoccurrence and new-onset ischemic stroke (IS) in patients with nonvalvular AF, and explore whether there is a high-risk period of IS after recurrent episodes of AF. Methods: A nested case-control study design was used. A total of 565 nonvalvular AF patients with new-onset IS after a follow-up of at least 2 years in the China-AF cohort were enrolled as the case group, and 1 693 nonvalvular AF patients without new-onset IS were matched as the control group at a ratio of 1∶3. Frequency and types of recurrent AF in the previous 1 or 2 years were compared between two groups, and the adjusted associations of AF reoccurrence with new onset IS were explored using conditional logistic regression analysis. The proportion of recurrent AF was compared between the case period and control period, and conditional logistic regression analysis was performed to calculate adjusted associations of case-period AF with IS. Results: The nested case-control study design results showed that the proportion of at least one record of recurrent AF in the previous 1 year was higher in the case group than in the control group (72.0% vs. 60.8%, P<0.05), and the recurrent AF was positively correlated with new-onset IS (adjusted OR=1.80, P<0.001). Similar results were also observed in the previous 2 years period. The case-crossover study design analysis showed that among 565 patients with new-onset IS, recurrent AF in the case period was positively correlated with IS (adjusted OR=1.61, P=0.003). Conclusion: Recurrent AF is associated with IS, and there may be a high-risk period of IS after recurrent episodes of AF.

Imputation method for dropout in single-cell transcriptome data / 生物医学工程学杂志

Single-cell transcriptome sequencing (scRNA-seq) can resolve the expression characteristics of cells in tissues with single-cell precision, enabling researchers to quantify cellular heterogeneity within populations with higher resolution, revealing potentially heterogeneous cell populations and the dynamics of complex tissues. However, the presence of a large number of technical zeros in scRNA-seq data will have an impact on downstream analysis of cell clustering, differential genes, cell annotation, and pseudotime, hindering the discovery of meaningful biological signals. The main idea to solve this problem is to make use of the potential correlation between cells and genes, and to impute the technical zeros through the observed data. Based on this, this paper reviewed the basic methods of imputing technical zeros in the scRNA-seq data and discussed the advantages and disadvantages of the existing methods. Finally, recommendations and perspectives on the use and development of the method were provided.