1.The Diversity of Filamentous Morphologies and Magnetic Sensitivity Modulated by Diverse MagR Expression in Bacteria
Ya-Fei CHANG ; Jing ZHANG ; Peng ZHANG ; Xiu-Juan ZHOU ; Meng-Ke WEI ; Tian-Tian CAI ; Pei-Qi HE ; Jun-Feng WANG ; Can XIE
Progress in Biochemistry and Biophysics 2026;53(5):1439-1456
Objective Magnetoreception, the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation, remains a molecularly unresolved mystery in sensory biology. The putative magnetoreceptor (MagR, previously known as IscA1) is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism; however, the functional diversity among its cross-species homologs remains poorly understood. Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering. Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote, non-invasive magnetic modulation represents a crucial goal in this field with significant application potential. Therefore, this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities, screen for MagR-based magnetically sensitive morphology engineering pathways, and reveal the underlying molecular mechanisms. Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli (E. coli). To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins, we utilized high-throughput automated bright-field microscopic imaging and scanning electron microscopy (SEM). Furthermore, comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays, electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) absorption, and circular dichroism (CD) spectroscopy. Additionally, 100 mT static magnetic field (SMF) exposure experiments were conducted to assess magnetically tunable phenotypes, while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device (SQUID) magnetometer. Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation. From this comprehensive screen, two distinct morphological patterns were identified: hydra (Hydra vulgaris) MagR (hyMagR) promoted uniform cell elongation and filamentation, exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF. In contrast, pigeon (Columba livia) MagR (clMagR) induced only low-frequency, extreme filamentation (sporadically exceeding 80 μm) with a relatively weaker magnetic morphological response. Mechanistically, our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation. Specifically, hyMagR preferentially binds ferrous iron (Fe2+), whereas clMagR favors ferric iron (Fe3+) and forms more stable iron-sulfur clusters. Intriguingly, although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR, its cellular magnetic response was weaker. We hypothesize that the Fe2+-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species (ROS) via the Fenton reaction. Exposure to an SMF synergizes with this primed redox state, triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation. Conclusion Our findings identify the Fe2+/Fe3+ redox state as a critical determinant of MagR-mediated morphological remodeling and magnetic responsiveness. This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications, and provides a plausible framework, which potentially combines intrinsic protein magnetism with redox-state modulation, for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.
2.The Diversity of Filamentous Morphologies and Magnetic Sensitivity Modulated by Diverse MagR Expression in Bacteria
Ya-Fei CHANG ; Jing ZHANG ; Peng ZHANG ; Xiu-Juan ZHOU ; Meng-Ke WEI ; Tian-Tian CAI ; Pei-Qi HE ; Jun-Feng WANG ; Can XIE
Progress in Biochemistry and Biophysics 2026;53(5):1439-1456
Objective Magnetoreception, the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation, remains a molecularly unresolved mystery in sensory biology. The putative magnetoreceptor (MagR, previously known as IscA1) is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism; however, the functional diversity among its cross-species homologs remains poorly understood. Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering. Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote, non-invasive magnetic modulation represents a crucial goal in this field with significant application potential. Therefore, this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities, screen for MagR-based magnetically sensitive morphology engineering pathways, and reveal the underlying molecular mechanisms. Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli (E. coli). To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins, we utilized high-throughput automated bright-field microscopic imaging and scanning electron microscopy (SEM). Furthermore, comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays, electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) absorption, and circular dichroism (CD) spectroscopy. Additionally, 100 mT static magnetic field (SMF) exposure experiments were conducted to assess magnetically tunable phenotypes, while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device (SQUID) magnetometer. Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation. From this comprehensive screen, two distinct morphological patterns were identified: hydra (Hydra vulgaris) MagR (hyMagR) promoted uniform cell elongation and filamentation, exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF. In contrast, pigeon (Columba livia) MagR (clMagR) induced only low-frequency, extreme filamentation (sporadically exceeding 80 μm) with a relatively weaker magnetic morphological response. Mechanistically, our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation. Specifically, hyMagR preferentially binds ferrous iron (Fe2+), whereas clMagR favors ferric iron (Fe3+) and forms more stable iron-sulfur clusters. Intriguingly, although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR, its cellular magnetic response was weaker. We hypothesize that the Fe2+-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species (ROS) via the Fenton reaction. Exposure to an SMF synergizes with this primed redox state, triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation. Conclusion Our findings identify the Fe2+/Fe3+ redox state as a critical determinant of MagR-mediated morphological remodeling and magnetic responsiveness. This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications, and provides a plausible framework, which potentially combines intrinsic protein magnetism with redox-state modulation, for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.
3.Research on The Role of Dopamine in Regulating Sleep and Wakefulness Through Exercise
Li-Juan HOU ; Ya-Xuan GENG ; Ke LI ; Zhao-Yang HUANG ; Lan-Qun MAO
Progress in Biochemistry and Biophysics 2025;52(1):88-98
Sleep is an instinctive behavior alternating awakening state, sleep entails many active processes occurring at the cellular, circuit and organismal levels. The function of sleep is to restore cellular energy, enhance immunity, promote growth and development, consolidate learning and memory to ensure normal life activities. However, with the increasing of social pressure involved in work and life, the incidence of sleep disorders (SD) is increasing year by year. In the short term, sleep disorders lead to impaired memory and attention; in the longer term, it produces neurological dysfunction or even death. There are many ways to directly or indirectly contribute to sleep disorder and keep the hormones, including pharmacological alternative treatments, light therapy and stimulus control therapy. Exercise is also an effective and healthy therapeutic strategy for improving sleep. The intensities, time periods, and different types of exercise have different health benefits for sleep, which can be found through indicators such as sleep quality, sleep efficiency and total sleep time. So it is more and more important to analyze the mechanism and find effective regulation targets during sleep disorder through exercise. Dopamine (DA) is an important neurotransmitter in the nervous system, which not only participates in action initiation, movement regulation and emotion regulation, but also plays a key role in the steady-state remodeling of sleep-awakening state transition. Appreciable evidence shows that sleep disorder on humans and rodents evokes anomalies in the dopaminergic signaling, which are also implicated in the development of psychiatric illnesses such as schizophrenia or substance abuse. Experiments have shown that DA in different neural pathways plays different regulatory roles in sleep behavior, we found that increasing evidence from rodent studies revealed a role for ventral tegmental area DA neurons in regulating sleep-wake patterns. DA signal transduction and neurotransmitter release patterns have complex interactions with behavioral regulation. In addition, experiments have shown that exercise causes changes in DA homeostasis in the brain, which may regulate sleep through different mechanisms, including cAMP response element binding protein signal transduction, changes in the circadian rhythm of biological clock genes, and interactions with endogenous substances such as adenosine, which affect neuronal structure and play a neuroprotective role. This review aims to introduce the regulatory effects of exercise on sleep disorder, especially the regulatory mechanism of DA in this process. The analysis of intracerebral DA signals also requires support from neurophysiological and chemical techniques. Our laboratory has established and developed an in vivo brain neurochemical analysis platform, which provides support for future research on the regulation of sleep-wake cycles by movement. We hope it can provide theoretical reference for the formulation of exercise prescription for clinical sleep disorder and give some advice to the combined intervention of drugs and exercise.
4.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
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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*
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Carcinoma, Lewis Lung/pathology*
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Drugs, Chinese Herbal/administration & dosage*
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Male
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Mice
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Signal Transduction/drug effects*
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Mice, Inbred C57BL
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Transcription Factor CHOP/genetics*
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Ointments/administration & dosage*
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Humans
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Cell Proliferation/drug effects*
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Antineoplastic Agents/administration & dosage*
5.Effects of total extract of Anthriscus sylvestris on immune inflammation and thrombosis in rats with pulmonary arterial hypertension based on TGF-β1/Smad3 signaling pathway.
Ya-Juan ZHENG ; Pei-Pei YUAN ; Zhen-Kai ZHANG ; Yan-Ling LIU ; Sai-Fei LI ; Yuan RUAN ; Yi CHEN ; Yang FU ; Wei-Sheng FENG ; Xiao-Ke ZHENG
China Journal of Chinese Materia Medica 2025;50(9):2472-2483
This study aimed to explore the effects and mechanisms of total extracts from Anthriscus sylvestris on pulmonary hypertension in rats. Sixty male SD rats were divided into normal(NC) group, model(M) group, positive drug sildenafil(Y) group, low-dose A. sylvestris(ES-L) group, medium-dose A. sylvestris(ES-M) group, and high-dose A. sylvestris(ES-H) group. On day 1, rats were intraperitoneally injected with monocrotaline(60 mg·kg~(-1)) to induce pulmonary hypertension, and the rat model was established on day 28. From days 15 to 28, intragastric administration of the respective treatments was performed. After modeling and treatment, small animal echocardiography was used to detect the right heart function of the rats. Arterial blood gas was measured using a blood gas analyzer. Hematoxylin and eosin(HE) staining and Masson staining were performed to observe cardiopulmonary pathological damage. Flow cytometry was used to detect apoptosis in the lung and myocardial tissues and reactive oxygen species(ROS) levels. Western blot was applied to detect the expression levels of transforming growth factor-β1(TGF-β1), phosphorylated mothers against decapentaplegic homolog 3(p-Smad3), Smad3, tissue plasminogen activator(t-PA), and plasminogen activator inhibitor-1(PAI-1) in lung tissue. A blood routine analyzer was used to measure inflammatory immune cell levels in the blood. Enzyme-linked immunosorbent assay(ELISA) was used to detect the expression levels of P-selectin and thromboxane A2(TXA2) in plasma. The results showed that, compared with the NC group, right heart hypertrophy index, right ventricular free wall thickness, right heart internal diameter, partial carbon dioxide pressure(PaCO_2), apoptosis in cardiopulmonary tissue, and ROS levels were significantly increased in the M group. In contrast, the ratio of pulmonary blood flow acceleration time(PAT)/ejection time(PET), right cardiac output, change rate of right ventricular systolic area, systolic displacement of the tricuspid ring, oxygen partial pressure(PaO_2), and blood oxygen saturation(SaO_2) were significantly decreased in the M group. After administration of the total extract of A. sylvestris, right heart function and blood gas levels were significantly improved, while apoptosis in cardiopulmonary tissue and ROS levels significantly decreased. Further testing revealed that the total extract of A. sylvestris significantly decreased the levels of interleukin-1β(IL-1β), interleukin-6(IL-6), and PAI-1 proteins in lung tissue, while increasing the expression of t-PA. Additionally, the extract reduced the levels of inflammatory cells such as leukocytes, lymphocytes, granulocytes, and monocytes in the blood, as well as the levels of P-selectin and TXA2 in plasma. Metabolomics results showed that the total extract of A. sylvestris significantly affected metabolic pathways, including arginine biosynthesis, tyrosine metabolism, and taurine and hypotaurine metabolism. In conclusion, the total extract of A. sylvestris may exert an anti-pulmonary hypertension effect by inhibiting the TGF-β1/Smad3 signaling pathway, thereby alleviating immune-inflammatory responses and thrombosis.
Animals
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Male
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Smad3 Protein/metabolism*
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Transforming Growth Factor beta1/metabolism*
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Rats, Sprague-Dawley
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Rats
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Signal Transduction/drug effects*
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Hypertension, Pulmonary/genetics*
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Thrombosis/immunology*
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Drugs, Chinese Herbal/administration & dosage*
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Humans
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Apoptosis/drug effects*
6.Lipid Droplet Biogenesis at the Endoplasmic Reticulum: Orchestrating Nucleation, Membrane Budding, and Expansion
Yue YU ; Wei-Ke JI ; Juan XIONG
Progress in Biochemistry and Biophysics 2025;52(9):2189-2204
Lipid droplets (LDs) are dynamic organelles that are ubiquitous across most organisms, including animals, plants, protists, and microorganisms. Their core consists of neutral lipids, surrounded by a phospholipid monolayer adorned with a specific set of proteins. As critical intracellular hubs of metabolic regulation, lipid droplets play essential roles in maintaining physiological homeostasis and contributing to the progression of various pathological processes. They store neutral lipids for energy production during periods of starvation or for membrane biosynthesis, and they sequester fatty acids to mitigate lipotoxicity. Clinically, dysregulation of lipid droplet function is associated with a wide range of diseases, including metabolic dysfunction-associated steatotic liver disease (MASLD), obesity, type 2 diabetes mellitus (T2DM), neurodegenerative disorders, and cancer. Research into the biological functions of lipid droplets—as dynamic organelles and their links to multiple diseases—has emerged as a cutting-edge focus in cell biology. In recent years, significant advances have been made in understanding lipid droplet biogenesis. Researchers have developed a more refined framework that elucidates how LDs are assembled in the endoplasmic reticulum (ER). Triacylglycerols and sterol esters are synthesized between the inner and outer leaflets of the ER bilayer, and when they exceed the critical nucleation concentration (CNC), they coalesce to form neutral lipid lenses. These then bud from the ER under the coordinated action of key proteins such as Seipin, fat storage-inducing transmembrane protein 2 (FIT2), and the peroxisomal membrane protein Pex30. This budding process is driven by changes in membrane curvature and surface tension, induced by the asymmetric distribution of phospholipids. Nascent lipid droplets recruit lipid-synthesizing enzymes via ER-LD bridging structures, enabling localized lipid production and surface expansion, ultimately resulting in the formation of mature LDs. Biochemical and biophysical approaches have revealed important features of this process, underscoring the critical roles of ER membrane biophysical properties and specific phospholipids. Structural biology and proteomic studies have identified key regulators—particularly Seipin and FIT2—as central players in LD biogenesis. This review systematically summarizes recent advances in the molecular mechanisms of LD biogenesis. It delves into the processes of LD nucleation, membrane budding, and expansion in eukaryotic cells, with a special focus on how core factors such as Seipin and FIT2 dynamically regulate LD morphology. In addition, it examines the mechanisms and pathways by which class I and class II proteins are targeted to LDs, compares LD biogenesis involving different neutral lipid cores, and discusses the disease relevance of specific regulatory proteins. Finally, the review outlines critical unresolved questions in the field of LD biogenesis, offering clear directions for future research and providing a comprehensive framework for deepening our understanding of LD formation and its implications for disease intervention.
7.Research progress of transcriptomics sequencing technology in evaluating human endometrial receptivity
Li-Na MA ; Hai-Ning QI ; Mei LIU ; Yang LIU ; Hang GE ; Feng-Juan LU ; Xiao-Ke WU ; Ying QIN
Medical Journal of Chinese People's Liberation Army 2025;50(5):607-611
Good endometrial receptivity is an essential factor for embryo implantation,and gene expression in endometrial tissue during the window of implantation(WOI)is closely related to receptivity.Transcriptome sequencing technology enables the identification of gene expression profiles of endometrium during different menstrual phases,as well as microRNAs and long-chain non-coding RNA sequences involved in regulating gene expression.Combining this technology with bioinformatics analysis provides a better understanding of specific gene expression during the receptive period and offers technical support for studying its regulatory mechanism.Moreover,gene expression profiles of the endometrium during different menstrual phases hold significant clinical application value for accurately assessing endometrium receptivity in infertility patients and those with repeated implantation failure,thereby guiding individualized embryo transfer strategies.This review summarizes the progress of transcriptome sequencing in evaluating human endometrial receptivity and discusses future research directions.This review aims to understand the complex molecular mechanisms of endometrial receptivity formation and regulation from the transcriptional level,in order to improve the implantation rate of embryos in assisted reproductive technology and reduce the abortion rate.
8.The impact of 125I seeds strand length on different reference points dose
Ke XU ; Dingxin WANG ; Guozhang XING ; Huimin YU ; Jinxin ZHAO ; Zezhou LIU ; Zeyang WANG ; Hongtao ZHANG ; Juan WANG
Journal of Interventional Radiology 2025;34(6):609-613
Objective To investigate the effect of different strand lengths of 125I seeds with the same activity on the dose of different reference points around the seeds.Methods The scanned images were transferred to the three-dimensional treatment planning system(3D-TPS)according to DICOM format.The target volume was delineated at 5 mm and 10 mm above and below the center of the phantom,and a 0.8 mCi seeds strand was simulated.The 1-20 seeds were arranged with an equal spacing of 5 mm(5 mm-100 mm).The 5 mm points above and below the center of the seeds strand were defined as point A and point A',and the 10 mm points above and below the center were defined as point B and point B'.5 mm above and below the edge of the seeds strand on the left side were defined as AL points and AL'points,and 5 mm above and below the edge of the seeds strand on the right side were defined as AR points and AR'points.Similarly,points 10 mm above the above mentioned positions were defined as BL points,BL'points,BR points,BR'points.The average dose symmetry points were measured at AL,AL',AR,and 5 mm,10 mm,15 mm and 20 mm inside AR' of the 45 mm-100 mm seeds strand.The dose at the center was compared with the dose at the end points.The dose at the center point A was compared with the average dose at the symmetry points of 5 mm,10 mm,15 mm and 20 mm inside of the end points AL,AL',AR and AR',and the dose at each point was curve fitting.The correlation between each point and seeds strands of different lengths was analyzed.Results There was a positive correlation between the dose and the length of each point.There was no statistically significant difference between the center point and the end point.There was a statistically significant difference in dosage at points 5 mm and 10 mm inside from point A,while there was no statistically significant difference in dosage at points 15 mm and 20 mm inside from point A.The dose of A,A',B and B' point increased steadily with the increase of seed chain length,and the fitting curves were obtained respectively:y=e(-0.620/x+5.28)(R2=0.992),y=e(-0.640/x+5.34)(R2=0.987),y=e(-0.82/x+4.80)(R2=0.984),y=e(-0.82/x+4.83)(R2=0.9g1).Conclusion The doses at points A,A',B,and B'are positively correlated with seeds strand length and have a high degree of stability.Point A can be used as a reference point for the target area dose of the seeds strand,and point B can be used as a reference point for the dose to critical organs.The dose at other positions is more variable and thus has a certain degree of uncertainty as a reference point for the seeds strand dose.
9.Correlation between dose distribution and implantation duration of 125I seed strand under the simulated curvature of the cavity condition
Zezhou LIU ; Dingxin WANG ; Guozhang XING ; Jinxin ZHAO ; Ke XU ; Hongtao ZHANG ; Juan WANG
Journal of Interventional Radiology 2025;34(11):1213-1217
Objective To investigate the relationship between the absorbed dose and implantation duration at the target area and at the critical organ dose reference points in the application of radioactive 125I seed strands for the treatment of intraluminal tumors.Methods A self-developed 125I seed strand arc template with a 30-degree angle was used to place 10 seeds(each with activity of 1.0mCi)into the template.CT-based DICOM images were transferred to a treatment planning system(TPS)for dose calculation.Absorbed doses at multiple time points(from day 5 to day 90 with a 5-day interval)were measured at following four specific locations:point A'(5 mm inside the arc center),point A(5 mm outside the arc center),point B(10 mm outside the arc center),and point B'(10 mm inside the arc center).The TPS was first used to calculate the expected absorbed doses,followed by actual absorbed dose measurements over the 90-day period.The expected absorbed doses were calculated,and then the actual absorbed doses were calculated.The time-dose relationship of the above points was analyzed,and the curves and equations were obtained.Results The expected absorbed doses at points A',A,B,and B'were 221.36,196.39,115.78,and 136.32 Gy,respectively.The time(x)-dose(y)relationships of all the above points followed a quadratic function relationship in the form of y=c+bx-ax2.Within the time range of 5-90 days,the actual absorbed dose increased with the prolongation of time,and the increase speed showed a pattern of first fast and then slow.The increase in speed was fast within 20 days,than became stable between 20-75 days,and after 75 days the increase in speed became to slow down.Conclusion When using 125I seed strands to treat intraluminal tumors,the actual absorbed dose of the tumor needs to be accurately calculated based on the implantation duration.The actual absorbed dose initially accumulates rapidly and decreases significantly after 75 days.It is recommended to replace the 125I seed strand with a new one after implanting it for approximately 75 days.
10.The impact of 125I seeds strand radian on the dose of different reference points
Jinxin ZHAO ; Dingxin WANG ; Guozhang XING ; Ke XU ; Zezhou LIU ; Huimin YU ; Zeyang WANG ; Juan WANG ; Hongtao ZHANG
Journal of Interventional Radiology 2025;34(12):1333-1337
Objective To investigate the impact of different 125I seeds strand radian on the dose of different reference points around the seeds.Methods CT scan of self-developed radioactive particle radiation dose measurement phantom was performed,the scanned images were transferred to the three-dimensional treatment planning system(TPS).The target area at the middle level of the model was drawn.The target volume was delineated at 5 mm and 10 mm above and below the center of the phantom.125I seeds strand plans were designed with different radians,with a total length of 8 cm,seed spacing of 0 cm,activity of 0.8 mCi,and a total of 16 particles,with radians ranging from 30°to 170°,increasing by 10° increment.The point 5 mm vertically away from the center of the seeds strand towards the center was named A',and the point away from the center was named A.The point 10 mm vertically away from the center of the seeds strand towards the center was named B',and the point away from the center was named B.The doses at different radians were recorded,and the actual absorbed dose at 1-2 months after operation was calculated based on the particle activity decay formula.Results The doses at points A'and A were(218.3±23.1)and(201.5±16.0)Gy respectively(P=0.001).The actual absorbed doses at 1 month after operation were(65.5±6.9)and(60.5±4.8)Gy respectively(P=0.001),and the actual absorbed doses at 2 months after operation were(109.2±11.5)Gy and(100±7.9)Gy respectively(P=0.001).The doses at points B'and B were(95.9±11.0)Gy and(81.7±4.9)Gy respectively(P<0.001),and the actual absorbed doses at 1 month after operation were(28.8±3.3)Gy and(24.5±1.5)Gy respectively(P<0.001).The actual absorbed doses at 2 month after operation were(48.0±5.5)Gy and(41.0±2.4)Gy respectively(P<0.001).The doses at points A'and A gradually decreased with the increase of the radians,reaching the minimum value at 100 degrees,and then increased gradually,showing a cubic function change.The actual absorbed dose showed the same trend.The doses at points B'and B increased gradually with the increase of the radians,showing a cubic function change.Conclusion At different radians,the point doses and absorbed doses on the centrifugal side of the seeds strand are both less than those on the centripetal side.There is a cubic function relationship between the dose at the reference points and the radian of the seeds strand.

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