1.Ameliorative effect and mechanism of Forsythia suspensa-Lonicera japonica herb pair on acute lung injury via regulating serum exosomal miRNA
Zhaohua CHEN ; Shumin XIE ; Wanshun CHANG ; Yuqing HAN ; Yanwen CHEN ; Yanhui ZHU ; Mingzhuo CAO ; Haiying HUANG
China Pharmacy 2026;37(3):305-310
OBJECTIVE To study the ameliorative effect and mechanism of Forsythia suspensa-Lonicera japonica herb pair on acute lung injury (ALI) based on serum exosomal microRNA (miRNA). METHODS The rats were randomly divided into a blank group (normal saline), model group (nomal saline), and F. suspensa-L. japonica herb pair group (2.55 g/kg), with 10 rats in each group. Except for the blank group, the other groups were used to establish an ALI model by intratracheal dripping of 5 mg/ mL lipopolysaccharides. After modeling, each group was given relevant medicine/normal saline intragastrically, once a day, for 3 consecutive days. After the last medication, the pathological status of lung tissue was observed; lung wet-to-dry weight ratio and leukocyte counts in bronchoalveolar lavage fluid (BALF) were determined. The levels of inflammatory factors [tumor necrosis factor-α(TNF-α), interleukin-1β (IL-1β), IL-10] in BALF were determined. Exosomes were isolated from rat serum, and high- throughput sequencing technology was employed to screen differentially expressed miRNA within the exosomes, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Based on the screened differentially expressed miRNA and the enriched KEGG pathways, in vitro cellular experiments were conducted for validation. RESULTS The animal experimental results demonstrated that after intervention with the F. suspensa-L. japonica herb pair, the wet-to-dry weight ratio, the number of leukocytes in BALF, as well as the levels of TNF-α and IL-1β in BALF of ALI rats were all significantly reduced (P<0.01), while the level of IL-10 was significantly increased (P<0.01). The results of high-throughput sequencing experiments revealed that the F. suspensa-L. japonica herb pair could significantly up-regulate the expressions of miR-345-3p, miR-194-5p, miR-653-5p, and others in exosomes. Among them, the KEGG pathways involved in the target genes of differentially expressed miRNA included the hypoxia-inducible factor-1(HIF-1) signaling pathway, among others. The results of cellular E-mail:huang.haiying@126.com validation experiments showed that overexpressed miR-345-3p could significantly elevate the level of IL-10 in the cell supernatant (P<0.01), while significantly reducing the levels of TNF-α and IL-1β in the cell supernatant, as well as the mRNA and protein expression levels of protein kinase B1, phosphatidylinositol 3- kinase, and HIF-1α (P<0.01). CONCLUSIONS F. suspensa-L. japonica herb pair can alleviate inflammatory responses and thereby exert a therapeutic effect in improving ALI by up-regulating the expression of miR-345-3p in serum exosomes and inhibiting the activity of the HIF-1 signaling pathway.
2.Analysis of individual external radiation dose monitoring results in non-medical nuclear utilization units in Nanning City, China
Wei ZHANG ; Libo JIA ; Tanchun XIE ; Qing CHANG ; Qiqi HUANG
Chinese Journal of Radiological Health 2026;35(1):97-102
Objective To evaluate the levels and changes in occupational individual external radiation dose in non-medical nuclear utilization units in Nanning City, and to provide a basis for radiation protection in such units. Methods Thermoluminescent dosimeters were used to monitor individual radiation doses among radiation workers in 38 non-medical nuclear utilization units in Nanning City. The results were subjected to statistical analysis. Results From 2021 to 2023, a total of
3.Strategies for Building an Artificial Intelligence-Empowered Trusted Federated Evidence-Based Analysis Platform for Spleen-Stomach Diseases in Traditional Chinese Medicine
Bin WANG ; Huiying ZHUANG ; Zhitao MAN ; Lifeng REN ; Chang HE ; Chen WU ; Xulei HU ; Xiaoxiao WEN ; Chenggong XIE ; Xudong TANG
Journal of Traditional Chinese Medicine 2026;67(1):95-102
This paper outlines the development of artificial intelligence (AI) and its applications in traditional Chinese medicine (TCM) research, and elucidates the roles and advantages of large language models, knowledge graphs, and natural language processing in advancing syndrome identification, prescription generation, and mechanism exploration. Using spleen-stomach diseases as an example, it demonstrates the empowering effects of AI in classical literature mining, precise clinical syndrome differentiation, efficacy and safety prediction, and intelligent education, highlighting an upgraded research paradigm that evolves from data-driven and knowledge-driven approaches to intelligence-driven models. To address challenges related to privacy protection and regulatory compliance in cross-institutional data collaboration, a "trusted federated evidence-based analysis platform for TCM spleen-stomach diseases" is proposed, integrating blockchain-based smart contracts, federated learning, and secure multi-party computation. The deep integration of AI with privacy-preserving computing is reshaping research and clinical practice in TCM spleen-stomach diseases, providing feasible pathways and a technical framework for building a high-quality, trustworthy TCM big-data ecosystem and achieving precision syndrome differentiation.
4.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.
5.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.
6.Molecular biological research and molecular homologous modeling of Bw.03 subgroup
Li WANG ; Yongkui KONG ; Huifang JIN ; Xin LIU ; Ying XIE ; Xue LIU ; Yanli CHANG ; Yafang WANG ; Shumiao YANG ; Di ZHU ; Qiankun YANG
Chinese Journal of Blood Transfusion 2025;38(1):112-115
[Objective] To study the molecular biological mechanism for a case of ABO blood group B subtype, and perform three-dimensional modeling of the mutant enzyme. [Methods] The ABO phenotype was identified by the tube method and microcolumn gel method; the ABO gene of the proband was detected by sequence-specific primer polymerase chain reaction (PCR-SSP), and the exon 6 and 7 of the ABO gene were sequenced and analyzed. Homologous modeling of Bw.03 glycosyltransferase (GT) was carried out by Modeller and analyzed by PyMOL2.5.0 software. [Results] The weakening B antigen was detected in the proband sample by forward typing, and anti-B antibody was detected by reverse typing. PCR-SSP detection showed B, O gene, and the sequencing results showed c.721 C>T mutation in exon 7 of the B gene, resulting in p. Arg 241 Trp. Compared with the wild type, the structure of Bw.03GT was partially changed, and the intermolecular force analysis showed that the original three hydrogen bonds at 241 position disappeared. [Conclusion] Blood group molecular biology examination is helpful for the accurate identification of ambiguous blood group. Homologous modeling more intuitively shows the key site for the weakening of Bw.03 GT activity. The intermolecular force analysis can explain the root cause of enzyme activity weakening.
7.Restoration of osteogenic differentiation of bone marrow mesenchymal stem cells in mice inhibited by cyclophosphamide with psoralen
Chenglong WANG ; Zhilie YANG ; Junli CHANG ; Yongjian ZHAO ; Dongfeng ZHAO ; Weiwei DAI ; Hongjin WU ; Jie ZHANG ; Libo WANG ; Ying XIE ; Dezhi TANG ; Yongjun WANG ; Yanping YANG
Chinese Journal of Tissue Engineering Research 2025;29(1):16-23
BACKGROUND:Psoralen has a strong anti-osteoporotic activity and may have a restorative effect on chemotherapy-induced osteoporosis. OBJECTIVE:To explore the restorative effect of psoralen on the osteogenic differentiation of bone marrow mesenchymal stem cells in mice inhibited by cyclophosphamide and its mechanism. METHODS:C57BL/6 mouse bone marrow mesenchymal stem cells were isolated and cultured.Effect of psoralen on viability of bone marrow mesenchymal stem cells was detected by MTT assay.Osteogenic induction combined with alkaline phosphatase staining was used to determine the optimal dose of psoralen to restore the osteogenic differentiation of bone marrow mesenchymal stem cells inhibited by cyclophosphamide.The mRNA expression levels of Runx2,alkaline phosphatase,Osteocalcin,osteoprotegerin,and Wnt/β-catenin signaling pathway-related genes Wnt1,Wnt4,Wnt10b,β-catenin,and c-MYC were measured by RT-qPCR at different time points under the intervention with psoralen.The protein expression of osteogenic specific transcription factor Runx2 and Wnt/β-catenin signaling pathway related genes Active β-catenin,DKK1,c-MYC,and Cyclin D1 was determined by western blot assay at different time points under the intervention with psoralen. RESULTS AND CONCLUSION:(1)There was no significant effect of different concentrations of psoralen on the viability of bone marrow mesenchymal stem cells.The best recovery of the inhibition of osteogenic differentiation of bone marrow mesenchymal stem cells caused by cyclophosphamide was under the intervention of psoralen at a concentration of 200 μmol/L.(2)Psoralen reversed the reduction in osteogenic differentiation marker genes Runx2,alkaline phosphatase,Osteocalcin and osteoprotegerin mRNA expression and Runx2 protein expression in bone marrow mesenchymal stem cells caused by cyclophosphamide conditioned medium.(3)Psoralen reversed the decrease in Wnt/β-catenin pathway-related genes Wnt4,β-catenin,c-MYC mRNA and Active β-catenin,c-MYC,and Cyclin D1 protein expression and the increase in DKK1 protein expression in bone marrow mesenchymal stem cells caused by cyclophosphamide conditioned medium.(4)The results showed that cyclophosphamide inhibited osteogenic differentiation of bone marrow mesenchymal stem cells in mice,and psoralen had a restorative effect on it.The best intervention effect was achieved at a concentration of 200 μmol/L psoralen,and this protective effect might be related to the activation of Wnt4/β-catenin signaling pathway by psoralen.
8.Mammalian pluripotent stem cells:effects on creating disease models,pathogenesis,drug discovery and personalized treatment
Wenqiang XU ; Haolin CHEN ; Chang YAN ; Tao XU ; Yabin XIE ; Xueling LI
Chinese Journal of Tissue Engineering Research 2025;29(1):136-146
BACKGROUND:The self-renewal and multi-directional differentiation of pluripotent stem cells possess the potential to revolutionize people's understanding of biology,medicine,development,and disease.Stem cells play an important role in the early stage of embryonic development,and the study of them could be beneficial to understanding of the basic principles of biological development and tissue or organ formation,exploring the potential mechanisms of various diseases,studying the repair and regeneration of damaged tissues or organs,and promoting drug discovery and personalized treatment. OBJECTIVE:To review the research progress of pluripotent stem cells,summarize and categorize the fundamental types of pluripotent stem cells,and elucidate the lineage situations of various types of pluripotent stem cells in common mammals. METHODS:PubMed,Web of Science,CNKI,and WanFang databases were searched systematically,with the keywords"pluripotent stem cells;embryonic stem cells;induced pluripotent stem cells;expanded potential stem cells;livestock pluripotent stem cells"in English and Chinese.The 99 articles related to mammalian pluripotent stem cells were systematically screened according to inclusion and exclusion criteria,and then reviewed. RESULTS AND CONCLUSION:(1)According to classical theory in mouse embryonic stem cell research,the pluripotent state of stem cells is divided into two forms:na?ve and primed.Na?ve state corresponds to the inner cell mass of pre-implantation embryos before attachment to the uterine wall,while primed state corresponds to the epiblast after implantation.These two states exhibit significant differences in epigenetic features,transcriptional activity,external signal dependency,and metabolic phenotype.It is later discovered that there is an intermediate state between na?ve and primed called formative pluripotency.Therefore,the pluripotency of pluripotent stem cells is a continuous developmental process rather than a unique cell state.(2)In addition to obtaining pluripotent stem cells from the inner cell mass,there are various methods and lineages for acquiring pluripotent stem cells,including embryonic germ cells established using primitive germ cells from mouse embryos,induced pluripotent stem cells created by the dedifferentiation of adult mouse and human fibroblasts with four factors—Oct3/4,Sox2,c-Myc,and Klf4;embryonic stem cell-like cell lines cultured from somatic cell nuclear transfer,parthenogenesis,neonatal or adult testicular or ovarian tissue,very small embryonic-like stem cells derived from various adult tissues and expanded pluripotent stem cells derived from pre-implantation stages.These pluripotent stem cells all share the common characteristics of continuous self-renewal,expressing core pluripotency factors and possessing the ability to differentiate into the three primary germ layers.(3)Currently,pluripotent stem cells are being used for disease modeling to study the mechanisms of various diseases and develop new drugs.Simultaneously,scientists are attempting to use pluripotent stem cells to cultivate various tissues and organs,offering new possibilities for regenerative medicine and transplantation.However,the clinical application of pluripotent stem cells faces safety challenges,including issues of cell mutations and immune rejection.Continual improvement in the methods of generating pluripotent stem cells will make them safer and more efficient for clinical applications.(4)Based on the methods of obtaining and lineage establishment of pluripotent stem cells in mice and humans,various types of pluripotent stem cells have been established in livestock,including embryonic stem cells,induced pluripotent stem cells,germ lineages of pluripotent stem cells,and expanded potential stem cells.Research on livestock pluripotent stem cells opens up new avenues for animal reproduction,breeding,genetic engineering,disease modeling,drug screening,and the conservation of endangered wildlife.
9.Multimodal neuroimaging evaluation of dopaminergic function, cortical metabolism, and functional connectivity alterations in early-onset Parkinson′s disease
Yan CHANG ; Xiaodan XU ; Jiajin LIU ; Shuwei SUN ; Yungang LI ; Hengge XIE ; Chao WEI ; Yuanyan CAO ; Ruozhuo LIU ; Ruimin WANG
Chinese Journal of Radiology 2025;59(11):1260-1266
Objective:To evaluate alterations in dopaminergic neurons, cortical metabolism, and functional connectivity networks in patients with early-onset Parkinson′s disease (EOPD) using multimodal neuroimaging.Methods:In this prospective cross-sectional study, 26 patients with EOPD and 16 healthy controls (HC group) were recruited from the PLA General Hospital between April and November 2023. All participants underwent integrated 11C-β-CFT PET/MR, 18F-FDG PET/CT brain imaging and resting-state functional MRI. Clinical assessments were conducted using the Unified Parkinson′s Disease Rating Scale and Hoehn-Yahr staging. Cognitive status was evaluated using the Mini-Mental State Examination and Montreal Cognitive Assessment. Standardized uptake value ratios for both 11C-β-CFT and 18F-FDG PET images were calculated using cerebellar gray matter as the reference region. Voxel-wise two-sample t-tests were performed to identify regions with significant group differences in tracer uptake. Seed regions showing altered 11C-β-CFT or 18F-FDG uptake were used to compute seed-based functional connectivity (FC) with all other brain voxels, and group differences in FC were assessed. Correlations between imaging metrics and clinical scales were evaluated using Pearson or Spearman analyses as appropriate. Results:Compared with HC group, EOPD group showed significantly reduced 11C-β-CFT uptake in the bilateral putamen, globus pallidus, and left temporal pole ( P<0.05), and decreased 18F-FDG uptake in the right superior frontal gyrus and anterior cingulate cortex ( P<0.05). Relative to HC group, EOPD group exhibited markedly lower FC between the right putamen and the left gyrus rectus as well as the right parahippocampal gyrus; the right superior frontal gyrus and the left gyrus rectus; the anterior cingulate cortex and the olfactory area of the frontal lobe, the left gyrus rectus, and the right superior parietal gyrus; the left temporal pole and the left orbitofrontal cortex as well as the left olfactory area ( P<0.05). Correlation analyses revealed no statistically significant associations between altered FC values and clinical scale scores in the EOPD group. Conclusions:Patients with EOPD demonstrate impaired nigrostriatal dopaminergic function, regional cortical hypometabolism, and aberrant functional connectivity across multiple brain networks.
10.Willingness-to-Pay for Combined Cancer Screening Among Rural Residents in Shandong Province
Xuan CHANG ; Jing XIE ; Qiuxia LI ; Yukun FENG ; Yanling ZHENG ; Nan ZHANG
China Cancer 2025;34(2):138-144
[Purpose]To investigate the acceptance and willingness-to-pay(WTP)of combined can-cer screening among rural residents in Shandong Province,and to analyze its influencing factors.[Methods]A face-to-face questionnaire survey was conducted among rural residents aged 40~70 in villages setected by cluster sampling from three counties(county level city or district)in Shan-dong Province.The questionnaire was developed using the method of double-bound dichotomous choice combined with open-ended questions in contingent valuation.The factors influencing inten-sity of WTP was analyzed with using single-factor and ordinary least squares regression models.[Results]A total of 962 subjects were surveyed.89.19%of the respondents were willing to accept cancer combined screening,and 62.00%were willing to pay part of the costs.The average of WTP was 963.67 CNY,which accounted for 32.12%of the total cost.The proportion of respon-dents who were willing to pay between 0~1 500 CNY was the highest(76.49%).In the multivariate analysis,age,sex and income had significant effects on the maximum payment of multi-cancer screening.[Conclusion]The acceptance of multi-cancer screening among rural residents in the study sites is high,but the willingness-to-pay is limited.The out-of-pocket payment for multi-can-cer screening should be controlled,and a co-payment mechanism among government,enterprises,social organizations and individuals should be explored.

Result Analysis
Print
Save
E-mail