1.Evolution and interpretation of diagnostic criteria for infective endocarditis
Hongkun QING ; Weiteng WANG ; Xuhua JIAN
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2026;33(01):30-36
Infective endocarditis (IE) is a life-threatening infectious disease. Although histopathological examination remains the gold standard for definitive diagnosis, it is performed in only a minority of patients; thus, the diagnosis of IE continues to rely predominantly on clinical manifestations. However, IE presents with highly variable systemic symptoms that often lack cardiac-specific features, posing significant diagnostic challenges. To address this complexity, multiple diagnostic criteria have been developed, integrating clinical presentation, imaging findings, and microbiological evidence. Over the past three decades, substantial shifts in the microbiological and epidemiological profiles of IE, coupled with advances in imaging modalities and laboratory diagnostics, have profoundly influenced diagnostic approaches, driving continuous refinement of diagnostic criteria. This review provides a comprehensive overview of the major diagnostic criteria for IE, traces their historical evolution, evaluates recent updates and diagnostic performance, and offers theoretical insights and practical implications to guide future research.
2.Functional characterization of flavonoid glycosyltransferase AmGT90 in Astragalus membranaceus.
Guo-Qing PENG ; Bing-Yan XU ; Jian-Ping HUANG ; Zhi-Yin YU ; Sheng-Xiong HUANG
China Journal of Chinese Materia Medica 2025;50(6):1534-1543
Astragalus membranaceus(A. membranaceus), a traditional tonic, contains flavonoids as one of its main bioactive components and key indicators for quality standard detection. These compounds predominantly exist in glycosylated forms after glycosylation modification within the plant. The catalytic products of flavonoid glycosyltransferases in A. membranaceus have been reported to be mostly monoglycosides, and only AmUGT28 catalyzes luteolin to form diglycosides. In this study, we cloned a glycosyltransferase gene, AmGT90, from A. membranaceus, with an ORF length of 1 335 bp, encoding 444 amino acids, and the protein had a relative molecular mass of 50.5 kDa. Phylogenetic tree analysis indicated that AmGT90 belongs to the UGT74 family. In vitro enzymatic reaction showed that AmGT90 had broad substrate specificity and could catalyze the glycosylation of various flavonoids, including isoflavones, flavones, flavanones, and chalcones. AmGT90 not only catalyzed the formation of monoglycosides but also diglycosides. In addition, the mechanism of AmGT90 catalyzing the formation of diglycosides from luteolin was preliminarily explored. The experimental results showed that AmGT90 may preferentially recognize C4'-OH of luteolin and then recognize C7-OH to form diglycosides. This study reported a glycosyltransferase from A. membranaceus capable of converting flavonoids into monoglycosides and diglycosides. This finding not only enhances our understanding of the biosynthetic pathways of flavonoid glycosides in A. membranaceus but also introduces a new component for glycoside production through synthetic biology.
Glycosyltransferases/chemistry*
;
Flavonoids/chemistry*
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Astragalus propinquus/classification*
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Phylogeny
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Glycosylation
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Plant Proteins/chemistry*
;
Substrate Specificity
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Cloning, Molecular
;
Amino Acid Sequence
3.Guiqi Yiyuan Ointment combined with cisplatin inhibits tumor growth in Lewis lung carcinoma-bearing mice by regulating PERK/eIF2α/ATF4/CHOP signaling pathway.
Nan YANG ; Jian-Qing LIANG ; Ke-Jun MIAO ; Qiang-Ping MA ; Jin-Tian LI ; Juan LI
China Journal of Chinese Materia Medica 2025;50(6):1592-1600
This study aims to investigate the anti-tumor effect and mechanism of Guiqi Yiyuan Ointment combined with cisplatin on Lewis lung carcinoma-bearing mice via the protein kinase RNA-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2α(eIF2α)/activated transcription factor 4(ATF4)/C/EBP homologous protein(CHOP) signaling pathway. Sixty SPF-grade male C57BL/6 mice were selected and assigned into a blank group and a modeling group by the random number table method. After modeling of the Lewis lung carcinoma, the mice in the modeling group were randomized into model, cisplatin(5 mg·kg~(-1), once a week), and low-, medium-, and high-dose(1.7, 3.5, and 7.05 g·kg~(-1), respectively, once a day) Guiqi Yiyuan Ointment+cisplatin(5 mg·kg~(-1)) groups(n=10). After 14 days of continuous intervention, the spleen, thymus, and tumor samples of the mice were collected, weighed, and recorded, and the spleen index, thymus index, and tumor suppression rate were calculated. Hematoxylin-eosin(HE) staining was employed to observe the pathological changes in the tumor tissue. The morphological changes of the endoplasmic reticulum of tumor cells were observed by transmission electron microscopy. The positive expression of phosphorylated eIF2α(p-eIF2α) and ATF4 in the tumor tissue was detected by immunofluorescence. Western blot was employed to determine the protein levels of phosphorylated PERK(p-PERK), p-eIF2α, ATF4, CHOP, B-cell lymphoma-2(Bcl-2), Bcl-2-associated X protein(Bax), cyclin-dependent kinase inhibitor 1A(p21), and cyclinD1 in the tumor tissue. Real-time fluorescent quantitative PCR was employed to determine the mRNA levels of PERK, eIF2α, ATF4, CHOP, Bax, Bcl-2, p21, and cyclinD1 in the tumor tissue. Compared with the blank group, the model group showed decreases in spleen index and thymus index(P<0.05). Compared with the model group, the cisplatin group showed decreases in spleen index and thymus index(P<0.05), and the medium-and high-dose Guiqi Yiyuan Ointment+cisplatin groups presented increases in spleen index and thymus index(P<0.05). In addition, the treatment groups all showed decreased tumor mass(P<0.05), increased tumor cell lysis and nuclear rupture, widened gap between rough endoplasmic reticulum, enhanced average fluorescence intensity of p-eIF2α and ATF4(P<0.05), up-regulated protein levels of p-PERK/PERK, p-eIF2α/eIF2α, ATF4, CHOP, Bax, and p21(P<0.05), down-regulated protein and mRNA levels of Bcl-2 and cyclinD1(P<0.05), and up-regulated mRNA levels of PERK, eIF2α, ATF4, CHOP, Bax, and p21(P<0.05). Compared with the cisplatin group, the combination groups showed increases in spleen index and thymus index(P<0.05) as well as mean optical density(P<0.05), and the high-dose Guiqi Yiyuan Ointment+cisplatin group showed decreased tumor mass(P<0.05). In addition, the medium-and high-dose Guiqi Yiyuan Ointment+cisplatin groups showcased enhanced average fluorescence intensity of p-eIF2α and ATF4(P<0.05), up-regulated protein levels of p-PERK/PERK, p-eIF2α/eIF2α, ATF4, CHOP, Bax, and p21(P<0.05), down-regulated protein and mRNA levels of Bcl-2 and cyclinD1(P<0.05), and up-regulated mRNA levels of PERK, eIF2α, ATF4, CHOP, Bax, and p21(P<0.05). In conclusion, Guiqi Yiyuan Ointment combined with cisplatin can effectively inhibit the growth of Lewis lung carcinoma in mice by regulating the expression of proteins related to the PERK/eIF2α/ATF4/CHOP signaling pathway and promoting cell cycle arrest and apoptosis.
Animals
;
Cisplatin/administration & dosage*
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Activating Transcription Factor 4/genetics*
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Eukaryotic Initiation Factor-2/genetics*
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eIF-2 Kinase/genetics*
;
Carcinoma, Lewis Lung/pathology*
;
Drugs, Chinese Herbal/administration & dosage*
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Male
;
Mice
;
Signal Transduction/drug effects*
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Mice, Inbred C57BL
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Transcription Factor CHOP/genetics*
;
Ointments/administration & dosage*
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Humans
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Cell Proliferation/drug effects*
;
Antineoplastic Agents/administration & dosage*
4.Mechanism of Yishen Jiangtang Decoction in regulating endoplasmic reticulum stress-mediated NLRP3 inflammasome to improve renal damage in diabetic nephropathy db/db mice.
Yun-Jie YANG ; Bin-Hua YE ; Chen QIU ; Han-Qing WU ; Bo-Wei HUANG ; Tong WANG ; Shi-Wei RUAN ; Fang GUO ; Jian-Ting WANG ; Ming-Qian JIANG
China Journal of Chinese Materia Medica 2025;50(10):2740-2749
This study aims to explore the mechanism through which Yishen Jiangtang Decoction(YSJTD) regulates endoplasmic reticulum stress(ERS)-mediated NOD-like receptor thermal protein domain associated protein 3(NLRP3) inflammasome to improve diabetic nephropathy(DN) in db/db mice. Thirty db/db mice were randomly divided into the model group, YSJTD group, ERS inhibitor 4-phenylbutyric acid(4-PBA) group, with 10 mice in each group. Additionally, 10 db/m mice were selected as the control group. The YSJTD group was orally administered YSJTD at a dose of 0.01 mL·g~(-1), the 4-PBA group was orally administered 4-PBA at a dose of 0.5 mg·g~(-1), and the control and model groups were given an equal volume of carboxylmethyl cellulose sodium. The treatments were administered once daily for 8 weeks. Food intake, water consumption, and body weight were recorded every 2 weeks. After the intervention, fasting blood glucose(FBG), glycosylated hemoglobin(HbA1c), urine microalbumin(U-mALB), 24-hour urine volume, serum creatinine(Scr), and blood urea nitrogen(BUN) were measured. Inflammatory markers interleukin-1β(IL-1β) and interleukin-18(IL-18) were detected using the enzyme-linked immunosorbent assay(ELISA). Renal pathology was assessed through hematoxylin-eosin(HE), periodic acid-Schiff(PAS), and Masson staining, and transmission electron microscopy(TEM). Western blot was used to detect the expression levels of glucose-regulated protein 78(GRP78), C/EBP homologous protein(CHOP), NLRP3, apoptosis-associated speck-like protein containing CARD(ASC), cysteinyl aspartate-specific proteinase(caspase-1), and gasdermin D(GSDMD) in kidney tissues. The results showed that compared to the control group, the model group exhibited poor general condition, increased weight and food and water intake, and significantly higher levels of FBG, HbA1c, U-mALB, kidney index, 24-hour urine volume, IL-1β, and IL-18. Compared to the model group, the YSJTD and 4-PBA groups showed improved general condition, increased body weight, decreased food intake, and lower levels of FBG, U-mALB, kidney index, 24-hour urine volume, and IL-1β. Specifically, the YSJTD group showed a significant reduction in IL-18 levels compared to the model group, while the 4-PBA group exhibited decreased water intake and HbA1c levels compared to the model group. Although there was a decreasing trend in water intake and HbA1c in the YSJTD group, the differences were not statistically significant. No significant differences were observed in BUN, Scr, and kidney weight among the groups. Renal pathology revealed that the model group exhibited more severe renal damage compared to the control group. Kidney sections from the model group showed diffuse mesangial proliferation in the glomeruli, tubular edema, tubular dilation, significant inflammatory cell infiltration in the interstitium, and increased glycogen staining and blue collagen deposition in the basement membrane. In contrast, the YSJTD and 4-PBA groups showed varying degrees of improvement in renal damage, glycogen staining, and collagen deposition, with the YSJTD group showing more significant improvements. TEM analysis indicated that the model group had extensive cytoplasmic edema, homogeneous thickening of the basement membrane, fewer foot processes, and widening of fused foot processes. In the YSJTD and 4-PBA groups, cytoplasmic swelling of renal tissues was reduced, the basement membrane remained intact and uniform, and foot process fusion improved.Western blot results indicated that compared to the control group, the model group showed upregulation of GRP78, CHOP, GSDMD, NLRP3, ASC, and caspase-1 expression. In contrast, both the YSJTD and 4-PBA groups showed downregulation of these markers compared to the model group. These findings suggest that YSJTD exerts a protective effect against DN by alleviating NLRP3 inflammasome activation through the inhibition of ERS, thereby improving the inflammatory response in db/db DN mice.
Animals
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Endoplasmic Reticulum Stress/drug effects*
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Diabetic Nephropathies/metabolism*
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NLR Family, Pyrin Domain-Containing 3 Protein/genetics*
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Drugs, Chinese Herbal/administration & dosage*
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Mice
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Inflammasomes/drug effects*
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Male
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Kidney/pathology*
;
Endoplasmic Reticulum Chaperone BiP
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Humans
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Interleukin-18/genetics*
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Mice, Inbred C57BL
5.Identification of tissue distribution components and mechanism of antipyretic effect of famous classical formula Dayuanyin.
Yu-Jie HOU ; Kang-Ning XIAO ; Jian-Yun BI ; Xin-Rui LI ; Ming SU ; Li-Jie WANG ; Yu-Qing WANG ; Dan-Dan SUN ; Hui ZHANG ; Xin-Jun ZHANG ; Shan-Xin LIU
China Journal of Chinese Materia Medica 2025;50(10):2810-2824
Based on the ultra performance liquid chromatography-quadrupole Exactive Orbitrap mass spectrometry(UPLC-Q-Exactive Orbitrap-MS) technology, combined with related literature, databases, and reference material information, this study qualitatively analyzed the components of Dayuanyin in the tissue of rats after gavage and employed molecular docking technology to predict the rationality of the mechanism behind the antipyretic effect of the in vivo components in Dayuanyin. A total of 21, 26, 20, 21, 14, and 31 prototype components and 3, 16, 3, 7, 5, and 24 metabolites were identified from the heart, liver, spleen, lung, kidney, and hypothalamus of the rats, respectively, and the binding ability of key components and targets was further verified by molecular docking. The results showed that all components had good binding ability with targets. The established UPLC-Q-Exactive Orbitrap-MS could effectively and quickly identify the Dayuanyin components distributed in tissue and preliminarily identify their metabolites. Many components were identified in the hypothalamus, which suggested that the components delivered to the brain should be focused on in the study on Dayuanyin in the treatment of febrile diseases. The molecular docking technology was used to predict the rationality of the mechanism behind its antipyretic effect, which lays the foundation for the clarification of the material basis and action mechanism of Dayuanyin, the development of new preparations, and the prediction of quality markers.
Animals
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Drugs, Chinese Herbal/administration & dosage*
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Rats
;
Molecular Docking Simulation
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Male
;
Antipyretics/metabolism*
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Rats, Sprague-Dawley
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Tissue Distribution
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Mass Spectrometry
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Chromatography, High Pressure Liquid
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Hypothalamus/metabolism*
6.Characterization of hippocampal components of Danzhi Xiaoyao Formula based on HPLC-Q-TOF-MS/MS and network pharmacology and assessment of its therapeutic potential for nervous system diseases.
Wen-Qing HU ; Hui-Yuan GAO ; Li YANG ; Yu-Xin WANG ; Hao-Jie CHENG ; Si-Yu YANG ; Mei-Yu ZHANG ; Jian SUN
China Journal of Chinese Materia Medica 2025;50(14):4053-4062
In this study, the pharmacodynamic components and potential pharmacological functions of Danzhi Xiaoyao Formula in treating nervous system diseases were investigated by hippocampal component characterization and network pharmacology. After rats were administrated with Danzhi Xiaoyao Formula by gavage, high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry(HPLC-Q-TOF-MS/MS) was employed to explore the components in the hippocampus of rats. Fifty-seven components were identified in the hippocampus of rats by comparing the extract of Danzhi Xiaoyao Formula, herbal components in the hippocampus after administration, and blank samples. KEGG and GO analyses predicted 74 core targets including GSK3B, MAPK1, AKT, IL6. These targets were involved in PI3K/Akt, NF-κB, MAPK, JAK/STAT, Wnt, and other signaling pathways. The results indicated that Danzhi Xiaoyao Formula may ameliorate other nervous system diseases enriched in DO, such as neurodegenerative diseases, cerebrovascular diseases, and mental and emotional disorders by mediating target pathways, inhibiting inflammation, reducing neuronal damage, and alleviating hippocampal atrophy. The relevant activities exhibited by this formula in nervous system diseases such as Alzheimer's disease, Parkinson's disease, and diabetic neuropathy have extremely high development value and are worthy of further in-depth research. This study provides a theoretical basis and practical guidance for expanding the application of Danzhi Xiaoyao Formula in the treatment of nervous system diseases.
Drugs, Chinese Herbal/administration & dosage*
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Animals
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Rats
;
Hippocampus/metabolism*
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Network Pharmacology
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Chromatography, High Pressure Liquid
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Tandem Mass Spectrometry
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Rats, Sprague-Dawley
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Male
;
Nervous System Diseases/genetics*
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Humans
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Signal Transduction/drug effects*
7.Effects of combined use of active ingredients in Buyang Huanwu Decoction on oxygen-glucose deprivation/reglucose-reoxygenation-induced inflammation and oxidative stress of BV2 cells.
Tian-Qing XIA ; Ying CHEN ; Jian-Lin HUA ; Qin SU ; Cun-Yan DAN ; Meng-Wei RONG ; Shi-Ning GE ; Hong GUO ; Bao-Guo XIAO ; Jie-Zhong YU ; Cun-Gen MA ; Li-Juan SONG
China Journal of Chinese Materia Medica 2025;50(14):3835-3846
This study aims to explore the effects and action mechanisms of the active ingredients in Buyang Huanwu Decoction(BYHWD), namely tetramethylpyrazine(TMP) and hydroxy-safflor yellow A(HSYA), on oxygen-glucose deprivation/reglucose-reoxygenation(OGD/R)-induced inflammation and oxidative stress of microglia(MG). Network pharmacology was used to screen the effective monomer ingredients of BYHWD and determine the safe concentration range for each component. Inflammation and oxidative stress models were established to further screen the best ingredient combination and optimal concentration ratio with the most effective anti-inflammatory and antioxidant effects. OGD/R BV2 cell models were constructed, and BV2 cells in the logarithmic growth phase were divided into a normal group, a model group, an HSYA group, a TMP group, and an HSYA + TMP group. Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of inflammatory cytokines such as interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), and interleukin-6(IL-6). Oxidative stress markers, including superoxide dismutase(SOD), nitric oxide(NO), and malondialdehyde(MDA), were also measured. Western blot was used to analyze the protein expression of both inflammation-related pathway [Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB)] and oxidative stress-related pathway [nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase-1(HO-1)]. Immunofluorescence was used to assess the expression of proteins such as inducible nitric oxide synthase(iNOS) and arginase-1(Arg-1). The most effective ingredients for anti-inflammatory and antioxidant effects in BYHWD were TMP and HSYA. Compared to the normal group, the model group showed significantly increased levels of IL-1β, TNF-α, IL-6, NO, and MDA, along with significantly higher protein expression of NF-κB, TLR4, Nrf2, and HO-1 and significantly lower SOD levels. The differences between the two groups were statistically significant. Compared to the model group, both the HSYA group and the TMP group showed significantly reduced levels of IL-1β, TNF-α, IL-6, NO, and MDA, lower expression of NF-κB and TLR4 proteins, higher levels of SOD, and significantly increased protein expression of Nrf2 and HO-1. Additionally, the expression of the M1-type MG marker iNOS was significantly reduced, while the expression of the M2-type MG marker Arg-1 was significantly increased. The results of the HSYA group and the TMP group had statistically significant differences from those of the model group. Compared to the HSYA group and the TMP group, the HSYA + TMP group showed further significant reductions in IL-1β, TNF-α, IL-6, NO, and MDA levels, along with significant reductions in NF-κB and TLR4 protein expression, an increase in SOD levels, and elevated Nrf2 and HO-1 protein expression. Additionally, the expression of the M1-type MG marker iNOS was reduced, while the M2-type MG marker Arg-1 expression increased significantly in the HSYA + TMP group compared to the TMP or HSYA group. The differences in the results were statistically significant between the HSYA + TMP group and the TMP or HSYA group. The findings indicated that the combined use of HSYA and TMP, the active ingredients of BYHWD, can effectively inhibit OGD/R-induced inflammation and oxidative stress of MG, showing superior effects compared to the individual use of either component.
Oxidative Stress/drug effects*
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Drugs, Chinese Herbal/pharmacology*
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Animals
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Mice
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Glucose/metabolism*
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Cell Line
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Inflammation/genetics*
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Oxygen/metabolism*
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Pyrazines/pharmacology*
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Microglia/metabolism*
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NF-E2-Related Factor 2/immunology*
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NF-kappa B/immunology*
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Toll-Like Receptor 4/immunology*
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Anti-Inflammatory Agents/pharmacology*
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Humans
8.Domestication progress of endangered Chinese medicinal material Fritillariae Cirrhosae Bulbus.
Ting XIAO ; Ming-Hao YANG ; Qiu-Ling WANG ; Qiang LYU ; Yu-Qing ZHENG ; Lian-Cheng XU ; Ma YU ; Jian-He WEI
China Journal of Chinese Materia Medica 2025;50(16):4483-4489
Fritillariae Cirrhosae Bulbus is the dried bulb of perennial herbaceous plants in the Fritillaria genus(Liliaceae family) and is a representative traditional Chinese medicinal material with distinctive regional characteristics. Clinically, it is widely used in the treatment of dry cough, bronchial asthma, and other respiratory diseases, possessing significant medicinal and economic value and being highly esteemed in TCM. Currently, Fritillariae Cirrhosae Bulbus primarily relies on wild harvesting. However, due to excessive collection, its wild resources have drastically declined, and all source species have been classified as category Ⅱ in the List of National Key Protected Wild Plants, exacerbating the supply-demand imbalance in the market. To mitigate this issue, large-scale cultivation through the domestication of wild Fritillariae Cirrhosae Bulbus has become an inevitable trend. However, its strict environmental requirements, low propagation efficiency, high seedling mortality, and immature cultivation techniques have severely hindered industrialization. This study investigates the domestication process of Fritillariae Cirrhosae Bulbus, focusing on seed propagation, seedling cultivation, and medicinal material production. It also reviews the species and distribution of wild resources, their endangered status, market supply-demand dynamics, and the historical and current development of domestication. The findings indicate that enhancing propagation efficiency, optimizing cultivation models, and distinguishing between seed propagation and medicinal material production are key measures to accelerate the industrialization of domesticated Fritillariae Cirrhosae Bulbus. This research aims to promote the industrialization of Fritillariae Cirrhosae Bulbus domestication and provide a reference model for the conservation and sustainable utilization of rare and endangered medicinal plant resources.
Fritillaria/chemistry*
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Endangered Species
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Plants, Medicinal/growth & development*
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Drugs, Chinese Herbal/economics*
;
China
9.Differences in intestinal absorption characteristics of Rubus multibracteatus extract in normal and inflammatory pain model rats by in-vitro everted intestine sac method.
Ming-Li BAO ; Qing ZHANG ; Yang JIN ; Yi CHEN ; Jian-Qing PENG ; Si-Ying CHEN ; Zhi-Jie MA ; Jian LIAO ; Jing HUANG ; Zi-Peng GONG
China Journal of Chinese Materia Medica 2025;50(16):4690-4704
This study compared the differences in intestinal absorption characteristics of eleven active components in Rubus multibracteatus(RM) extract(protocatechuic acid, tiliroside, scutellarin, luteoloside, astragalin, epicatechin, catechin, xanthotoxin, p-coumaric acid, caffeic acid, and apigenin-7-O-glucuronide) between normal rats and inflammatory pain model rats using the in-vitro everted intestinal sac model. The RM extract was administered at absorption concentrations of 25.0, 50.0, and 100.0 mg·mL~(-1). The contents of the eleven components in intestinal absorption solution samples were quantified by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), and their cumulative absorption(Q) and absorption rate constant(K_a) were calculated to evaluate the absorption characteristics of these components in normal rats and inflammatory pain model rats. The results show that except for catechin, epicatechin, and caffeic acid, the cumulative absorption-time curves of the other eight components(protocatechuic acid, tiliroside, scutellarin, luteoloside, astragalin, xanthotoxin, p-coumaric acid, and apigenin-7-O-glucuronide) exhibit an upward trend without saturation, with correlation coefficients(R~2) all > 0.9, indicating linear absorption. However, the overall absorption of all components is not dose-dependent with increasing concentration, suggesting that their absorption mechanisms are not solely passive diffusion. In both normal and model rats, the jejunum shows the highest absorption for all components except xanthotoxin. The overall absorption of seven components(excluding protocatechuic acid, caffeic acid, apigenin-7-O-glucuronide, and luteoloside) in normal rats is better than that in model rats across all intestinal segments. These findings indicate that the pathological state of inflammatory pain alters the intestinal absorption of RM extract, and its mechanism needs further investigation.
Animals
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Rats
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Intestinal Absorption/drug effects*
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Male
;
Rats, Sprague-Dawley
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Drugs, Chinese Herbal/metabolism*
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Disease Models, Animal
;
Pain/metabolism*
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Intestines/drug effects*
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Intestinal Mucosa/metabolism*
10.Junctophilin-2 MORN-Helix Domain: Structural Basis for Membrane Binding and Hypertrophic Cardiomyopathy-associated Mutations
Jing-Xin WANG ; Zhi-Wei LI ; Wei LIU ; Wen-Qing ZHANG ; Jian-Chao LI
Progress in Biochemistry and Biophysics 2025;52(8):2103-2116
ObjectiveJunctophilin-2 (JPH2) is an essential structural protein that maintains junctional membrane complexes (JMCs) in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum, thereby facilitating excitation-contraction (E-C) coupling. Mutations in JPH2 have been associated with hypertrophic cardiomyopathy (HCM), but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus (MORN) repeat motifs remain incompletely understood. This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis. MethodsA recombinant N-terminal fragment of mouse JPH2 (residues1-440), encompassing the MORN repeats and an adjacent helical region, was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain. Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features. Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells. In addition, site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations, including R347C, was used to evaluate their effects on membrane interaction and subcellular localization. ResultsThe crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6 Å, revealing a compact, elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration, forming a continuous hydrophobic core stabilized by alternating aromatic residues. A C-terminal α-helix further reinforced structural integrity. Conservation analysis identified the inner groove of the MORN array as a highly conserved surface, suggesting its role as a protein-binding interface. A flexible linker segment enriched in positively charged residues, located adjacent to the MORN motifs, was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes. Functional assays demonstrated that mutation of these basic residues impaired membrane association, while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays, despite preserving the overall MORN-Helix fold in structural modeling. ConclusionThis study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2, highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions. The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis. These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.

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