1.Anthocyanins from Lycium ruthenicum Murr combined with human adipose-derived pericytes/perivascular cells support proliferation of umbilical cord blood hematopoietic stem/progenitor cells
Yamei SHEN ; Yunxia NIU ; Tingting YANG ; Jie MA ; Daihong HU ; Bo ZHENG
Chinese Journal of Tissue Engineering Research 2025;29(1):58-64
BACKGROUND:Anthocyanin is one of the most important active components in Lycium ruthenicum Murr,which has antioxidant and immunomodulatory effects.CD146+human adipose-derived pericytes/perivascular cells(CD146+hAD-PCs)are the progenitors of bone marrow mesenchymal stem cells,which can promote the proliferation and differentiation of hematopoietic stem/progenitor cells in vitro.The support effect of anthocyanin in combination with CD146+hAD-PCs on umbilical cord blood hematopoietic stem/progenitor cells remains to be studied. OBJECTIVE:To investigate the supporting effect of anthocyanins in Lycium ruthenicum Murr(ALRM)combined with CD146+hAD-PCs on umbilical cord blood CD34+hematopoietic stem/progenitor cells(UCB CD34+HSPCs)in vitro. METHODS:The CCK-8 assay was used to detect the effect of different concentrations(0,200,400,600,800,1 000 mg/L)of ALRM on the proliferation of CD146+hAD-PCs.Flow cytometry was used to detect the effect of ALRM on the cell cycle of CD146+hAD-PCs.The co-culture experiments were divided into blank group,ALRM group,CD146+hAD-PCs group,and ALRM+CD146+hAD-PCs group to analyze the in vitro supporting effect of ALRM combined with CD146+hAD-PCs on UCB CD34+HSPCs.The number of expanded cells and the number of colony-forming units were compared at 1,2,and 4 weeks of co-culture.The immunophenotype of cells was detected by flow cytometry.The level of cytokines was detected by enzyme-linked immunosorbent assay. RESULTS AND CONCLUSION:(1)The cell viability of CD146+hAD-PCs was highest at an ALRM concentration of 200 mg/L,the proportion of G0/G1 phase cells decreased and the proportion of S and G2/M phase cells increased in CD146+hAD-PCs(P<0.01).(2)The change in number of UCB CD34+HSPCs cells in the ALRM+CD146+hAD-PCs group was higher than that in the ALRM group at 1,2,and 4 weeks of co-culture(all P<0.05),and higher than that in CD146+hAD-PCs group at 2 and 4 weeks of co-culture(all P<0.05).The number of cells in the ALRM group and blank group decreased gradually with the extension of co-culture time.(3)Colony forming capacity and immunophenotype analysis:The number of colony-forming units in the ALRM+CD146+hAD-PCs group was higher than that in the CD146+hAD-PCs group and ALRM group at 1 and 2 weeks of co-culture(P<0.05).The proportion of CD45+and CD34+CD33-cells in the ALRM+CD146+hAD-PCs group was higher than that in the CD146+hAD-PCs group at 1 and 2 weeks of co-culture(all P<0.01).(4)Changes in cytokines:Interleukin-2 level in the ALRM+CD146+hAD-PCs group was higher than that in the ALRM and CD146+hAD-PCs groups(P<0.05).The interleukin-3 content of the ALRM+CD146+hAD-PCs group was higher than that of the CD146+hAD-PCs group at 2 and 4 weeks(P<0.05).The expression level of granulocyte colony-stimulating factor in the ALRM+CD146+hAD-PCs group was higher than that in the CD146+hAD-PCs group at 1 week,and higher than that in the ALRM group and CD146+hAD-PCs group at 2 weeks(P<0.01).Interferon-γ content in the ALRM group and ALRM+CD146+hAD-PCs group was lower than that in the CD146+hAD-PCs group at 1,2,and 4 weeks of co-culture(P<0.01).(5)Due to the absence of stromal cells in the blank group,UCB CD34+HSPCs could not be counted after 1 week of co-culture and were not subjected to immunophenotyping,colony analysis,or cytokine assays.(6)In summary,ALRM can promote the expansion of UCB CD34+HSPCs in vitro by promoting CD146+hAD-PCs proliferation and cell cycle transformation,which is of great value in hematopoietic stem cell transplantation.
2.Comparison of short-term clinical efficacy between CO external fixation and internal fixation with steel plate in the treatment of unstable distal radius fractures.
Min-Rui FU ; Chang-Long SHI ; Yong-Zhong CHENG ; Ming-Ming MA ; Zheng-Lin NIU ; Hai-Xiang SUN ; Jing-Hua GAO ; Zhong-Kai WU ; Yi-Ming XU
China Journal of Orthopaedics and Traumatology 2025;38(1):10-17
OBJECTIVE:
To evaluate the short-term clinical efficacy of external fixation and internal fixation with steel plate in the treatment of unstable distal radius fractures (AO-23C type), based on the principles of Chinese osteosynthesis (CO).
METHODS:
Forty-eight patients with unstable distal radius fractures between January 2022 and February 2023 were retrospectively analyzed and divided into the CO external fixation group and internal fixation group. CO external fixation group consisted of 25 patients, including 7 males and 18 females, aged from 37 to 56 years old with an average of ( 52.6±11.3) years old. Among them, there were 7 patients of traffic accidents and 18 patients of falls, resulting in a total of 25 patients of closed fractures and no open fractures, the treatment was conducted using closed reduction and CO external fixation. The internal fixation group consisted of 23 patients, comprising 8 males and 15 females, age ranged from 41 to 59 years old, with an average age of(53.3±13.7) years old. Among them, 8 patients resulted from car accidents while the remaining 15 patients were caused by falls. All 23 patients were closed fractures without any open fractures observed. The technique of open reduction and internal fixation with steel plate was employed. The perioperative data, including injury-operation time, operation duration, blood loss, and length of hospital stay, were assessed in both groups. Additionally, the QuickDASH score and visual analogue scale (VAS) were evaluated. Range of motion and grip strength assessment, imaging findings such as palmar inclination angle, ulnar declination angle, radius length, articular surface step, intra-articular space measurements were also examined along with any complications.
RESULTS:
The follow-up duration ranged from 0 to 24 months, with an average duration of (16.0±3.8) months. The CO external fixation exhibited significantly shorter time from injury to operation (2.4±3.3) d vs (7.4±3.7) d, shorter operation duration (56.27±15.23) min vs (74.10±5.26) min, lower blood loss (14.52±6.54) ml vs (32.32±10.03) ml, and reduced hospitalization days (14.04±3.24 )d vs (16.45±3.05) d compared to the internal fixation group (P<0.05). The QuickDASH score at 12 months post-operation was (8.21±1.64) in the CO external fixation group, while no significant difference was observed in the internal fixation group (7.04±3.64), P>0.05. There were no statistically significant differences in VAS between two groups at 6 weeks, as well as 1 and 3 months post-surgery (P>0.05). Additionally, there were no significant disparities observed in terms of range of motion and grip strength between two groups at the 2-year follow-up after the operation (P>0.05). After 12 months of surgery, the CO external fixation group exhibited a significantly smaller palmar inclination angle (17.90±2.18) ° vs (19.87±3.21) °, reduced articular surface step (0.11±0.03) mm vs (0.17±0.02) mm, and shorter radius length (8.16±1.11) mm compared to the internal fixation group (9.59±1.02) mm, P<0.05. The ulnar deviation angle and intra-articular space did not show any significant difference between two groups (P>0.05). The reduced fell within the allowable range between the CO external fixation group (23 out of 25 cases) and the internal fixation group (21 out of 23 cases) was not statistically significant (P=0.29). There was no significant difference in complications between the two groups(P>0.05).
CONCLUSION
Both the CO external fixation and open reduction with plate internal fixation demonstrate clinical efficacy in managing unstable distal radius fractures. The CO external fixation offers advantages in shorter injury-to-operation times, reduced intraoperative blood loss, and decreased surgical durations, while radial shortening is more effectively controlled by internal fixation.
Humans
;
Male
;
Female
;
Middle Aged
;
Radius Fractures/physiopathology*
;
Adult
;
Bone Plates
;
Fracture Fixation, Internal/methods*
;
External Fixators
;
Retrospective Studies
;
Fracture Fixation/methods*
;
Wrist Fractures
3.Research Progress of the Wnt/β-catenin Signaling Pathway in the Regulation of Oxidative Stress and Its Impact on the Hematopoietic System --Review.
Journal of Experimental Hematology 2025;33(3):927-930
Excessive generation of reactive oxygen species (ROS) can lead to oxidative-antioxidative imbalance in the organism, resulting in oxidative stress. Hematopoietic stem/progenitor cells (HSPCs) exhibit high sensitivity to changes in ROS levels, and high levels of ROS can impair self-renewal capacity of HSPCs, leading to oxidative damage and even death. Wnt/β-catenin signaling pathway regulates hematopoiesis and plays an important role in determining the fate of stem cells, such as self-renewal, proliferation and differentiation of HSPCs. Studies have shown that Wnt/β-catenin signaling pathway is also closely related to oxidative stress. This article summarizes the relevant literature, and reviews the role of Wnt/β-catenin signaling pathway in oxidative stress, its impact on hematopoietic system, and the current research status of related mechanisms.
Oxidative Stress
;
Humans
;
Wnt Signaling Pathway
;
Hematopoietic Stem Cells
;
Reactive Oxygen Species/metabolism*
;
Hematopoietic System/metabolism*
;
beta Catenin/metabolism*
;
Hematopoiesis
4.Spermidine inactivates proteasome activity and enhances ferroptosis in prostate cancer.
Dan FENG ; Jian ZHANG ; Huanmin NIU ; Xiaoxue ZHENG ; Mengqi JIA ; Qiqi LU ; Jing WANG ; Wenxue GUO ; Qi SUN ; Huiqing YUAN ; Hongxiang LOU
Acta Pharmaceutica Sinica B 2025;15(4):2095-2113
The elevated polyamines, amine-rich molecules with diverse functions in pathophysiology processes, are implicated in contributing to tumorigenesis and progression. Whether and how they affect the efficacy of chemotherapy is incompletely understood. Our screening assays reveal that the supplement with a low dose of spermidine (Spd), one of the polyamines, enhances ferroptosis in prostate cancer cells as evidenced by increased lipid peroxidation and intracellular Fe2+ levels in vitro. Combination treatment with Spd and a low dose of ferroptosis inducer erastin synergistically augments anti-tumor efficacy with undetectable toxicity in mice. Analysis of RNA-seq data indicates that heme oxygenase 1 (HMOX1), an enzyme that catalyzes the cleavage of heme to release Fe2+, is significantly upregulated in response to Spd and erastin cotreatment. Spd mediated the hypusine modification of the eukaryotic initiation factor 5A (EIF5A) promotes the translation of the nuclear factor erythroid 2-related factor 2 (NRF2), subsequently leading to elevation of HMOX1. Moreover, Spd and erastin significantly inhibit proteasome activity which results in a decrease in proteasomal degradation of NRF2, although many proteasome-related genes are induced either by Spd or Spd plus erastin. Thus, in addition to its pro-oncogenic activity, the supplement of Spd improves antitumor activity in combination with ferroptosis inducers and offers an optional approach to cancer treatment.
5.Cytoplasmic and nuclear NFATc3 cooperatively contributes to vascular smooth muscle cell dysfunction and drives aortic aneurysm and dissection.
Xiu LIU ; Li ZHAO ; Deshen LIU ; Lingna ZHAO ; Yonghua TUO ; Qinbao PENG ; Fangze HUANG ; Zhengkun SONG ; Chuanjie NIU ; Xiaoxia HE ; Yu XU ; Jun WAN ; Peng ZHU ; Zhengyang JIAN ; Jiawei GUO ; Yingying LIU ; Jun LU ; Sijia LIANG ; Shaoyi ZHENG
Acta Pharmaceutica Sinica B 2025;15(7):3663-3684
This study investigated the role of the nuclear factor of activated T cells c3 (NFATc3) in vascular smooth muscle cells (VSMCs) during aortic aneurysm and dissection (AAD) progression and the underlying molecular mechanisms. Cytoplasmic and nuclear NFATc3 levels were elevated in human and mouse AAD. VSMC-NFATc3 deletion reduced thoracic AAD (TAAD) and abdominal aortic aneurysm (AAA) progression in mice, contrary to VSMC-NFATc3 overexpression. VSMC-NFATc3 deletion reduced extracellular matrix (ECM) degradation and maintained the VSMC contractile phenotype. Nuclear NFATc3 targeted and transcriptionally upregulated matrix metalloproteinase 9 (MMP9) and MMP2, promoting ECM degradation and AAD development. NFATc3 promoted VSMC phenotypic switching by binding to eukaryotic elongation factor 2 (eEF2) and inhibiting its phosphorylation in the VSMC cytoplasm. Restoring eEF2 reversed the beneficial effects in VSMC-specific NFATc3-knockout mice. Cabamiquine-targets eEF2 and inhibits protein synthesis-inhibited AAD development and progression in VSMC-NFATc3-overexpressing mice. VSMC-NFATc3 promoted VSMC switch and ECM degradation while exacerbating AAD development, making it a novel potential therapeutic target for preventing and treating AAD.
6.Metabolic engineering of Escherichia coli for the biosynthesis of O-acetyl-L-homoserine.
Lianggang HUANG ; Feng GAO ; Nuoran XU ; Junping ZHOU ; Kun NIU ; Bo ZHANG ; Zhiqiang LIU ; Yuguo ZHENG
Chinese Journal of Biotechnology 2025;41(1):256-270
O-acetyl-L-homoserine (OAH) is a promising platform compound for the production of L-methionine and other valuable compounds, while its low yield and low conversion rate limit the industrial application. To solve these problems, we constructed a strain for high OAH production with the previously constructed L-homoserine producer Escherichia coli HS33 as the chassis by systematic metabolic engineering. Firstly, PEP accumulation, pyruvate utilization, and OAH synthesis pathway (overexpressing aspB, aspA, and thrAC1034T) were enhanced to obtain an initial strain accumulating 13.37 g/L OAH. Subsequently, the co-factor synthesis genes were integrated to supply reducing power and energy, which increased the yield to 15.79 g/L. The OAH yield of the engineered strain OAH28 was further increased to 17.49 g/L by strengthening the acetic acid reuse pathway, improving the supply of acetyl-CoA, and regulating the expression of MetX from different sources. Finally, in a 5 L fermenter, OAH28 achieved an OAH titer of 47.12 g/L, with a glucose conversion rate of 32% and productivity of 0.59 g/(L·h). The results lay a foundation for increasing the OAH production by metabolic engineering and give insights into the industrial production of OAH.
Metabolic Engineering/methods*
;
Escherichia coli/genetics*
;
Homoserine/biosynthesis*
;
Fermentation
7.Construction and fermentation regulation of strains with high yields of echinocandin B.
Kun NIU ; Hongwei CAI ; Yixin YE ; Jinyue XU ; Zhiqiang LIU ; Yuguo ZHENG
Chinese Journal of Biotechnology 2025;41(4):1455-1466
Echinocandin B (ECB) is a key precursor of the antifungal drug anidulafungin. It is a secondary metabolite of Aspergillus nidulans, and its titer in fermentation is significantly affected by the ECB synthesis pathway and cell morphology. In this study, the key genes related to the transcription activation, hydroxylation, and cell morphology during ECB biosynthesis were investigated to increase the fermentation titer of ECB and to change the cell morphology of Aspergillus nidulans to reduce the viscosity of the fermentation broth. The results indicated that after overexpression of ecdB and ecdK, the ECB titer increased by 25.8% and 23.7%, respectively, compared with that of the wild-type strain, reaching (2 030.5±99.2) mg/L and (1 996.4±151.4) mg/L. However, the deletion of fksA associated with cell wall synthesis resulted in damage to the cell wall, affecting strain growth and product synthesis. The engineered strain overexpressing ecdB was fermented in a 50-L bioreactor, in which the ECB titer reached 2 234.5 mg/L. The findings laid a research foundation for the subsequent metabolic engineering of this strain.
Fermentation
;
Aspergillus nidulans/genetics*
;
Echinocandins/genetics*
;
Bioreactors/microbiology*
;
Fungal Proteins/biosynthesis*
;
Metabolic Engineering
8.Exploration and practice of teaching reform in Synthetic Biology.
Bo ZHANG ; Lianggang HUANG ; Aiping PANG ; Zheyan WU ; Junping ZHOU ; Xue CAI ; Lijuan WANG ; Kun NIU ; Liqun JIN ; Zhiqiang LIU ; Yuguo ZHENG
Chinese Journal of Biotechnology 2025;41(8):3311-3317
Synthetic biology is a crucial tool for the development of the bio-industry and bio-economy, representing a significant aspect of new quality productive forces. As a core course for graduate students in bioengineering, Synthetic Biology plays a vital role in ensuring the supply of essential talents for the development of the bio-industry in the new era. To better serve regional economic development and provide high-level talents for China's progress in the bio-industry, we analyzed typical issues encountered in the past teaching activities, set up a multi-disciplinary teaching team, optimized the course contents, adjusted the teaching mode, and mobilized students' learning interest. With the application of scientific research project as the starting point, we guided students to think and discuss deeply through the simulation of application writing and project defense, which improved students' critical thinking and innovative thinking. With industrialization as a focus, we explored a new training model combining production, education, and research through the joint practice base of the university and enterprises introduced typical cases of biomanufacturing to encourage students to engage in scientific research. The teaching reform significantly enhances the comprehensive abilities and national sentiments of graduate students. This paper hopes to serve as a reference for colleagues engaged in teaching in this field.
Synthetic Biology/education*
;
Teaching
;
China
;
Humans
9.Inhibitory effect of astragaloside Ⅳ on cisplatin-induced liver injury in mice and its mechanism
Kaiqi NIU ; He CHANG ; Guangfu LYU ; Pengyu ZHENG ; Xueting CHI ; Jia ZHOU ; Yuchen WANG ; Xiaowei HUANG
Journal of Jilin University(Medicine Edition) 2025;51(2):370-377
Objective:To investigate the inhibitory effect of astragaloside Ⅳ(AS-Ⅳ)on cisplatin(CDDP)-induced liver injury in the mice,and to elucidate its possible mechanism.Methods:Forty male C57BL/6 mice with body weights of 18-22 g were randomly divided into control group,model group,AS-Ⅳ group and adenosine 5'-monophosphate-activated protein kinase(AMPK)inhibitor(Compound C)+AS-Ⅳ group.The mice in control group and model group were gavaged with the same volume of normal saline,and the drug was administered continuously for 9 d.The mice in AS-Ⅳ group and Compound C+AS-Ⅳ group were given AS-Ⅳ aqueous solution(150 mg·kg-1·d-1),respectively.On the 6th day of experiment,the mice in Compound C+AS-Ⅳ group were intraperitoneally injected with Compound C(20 mg·kg-1),and on the 7th day,except for control group,the mice in other groups were intraperitoneally injected with 20 mg·kg-1 CDDP to establish the mouse liver injury models,and the mice were sacrificed 48 h later.Serum and liver tissues were collected,and the levels of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)in the serum of the mice,as well as the activities of superoxide dismutase(SOD)and catalase(CAT)and the levels of malondialdehyde(MDA)in the liver tissue of the mice in various groups were detected by kits.The pathomorphology of liver tissue of the mice in various groups were detected by HE staining.The expression levels of glutathione peroxidase 4(GPX4),ferritin heavy chain 1(FTH1)and ferroptosis inhibitory protein 1(FSP1)proteins in liver tissue of the mice in various groups were detected by immunohistochemical staining,and the expression levels of nuclear factor-E2-related factor 2(Nrf2),heme oxygenase-1(HO-1)and AMPK proteins in liver tissue of the mice in various groups were detected by Western blotting method.Results:Compared with control group,the levels of AST and ALT in serum of the mice in model group were increased(P<0.01),the activities of SOD and CAT in the liver tissue were significantly decreased(P<0.01),and the MDA level was increased(P<0.01);compared with model group,the levels of AST and ALT in serum of the mice in AS-Ⅳ group were decreased(P<0.01),the MDA level in the liver tissue was decreased(P<0.01),and the activities of SOD and CAT were increased(P<0.01);compared with AS-Ⅳ group(P<0.01),the levels of AST and ALT in serum of the mice in Compound C+AS-Ⅳ group were increased(P<0.01),the level of MDA in liver tissue was increased(P<0.05),and the activities SOD and CAT were decreased(P<0.01).The HE staining results showed that compared with control group,the liver damage degree of the mice in model group was enhanced,the hepatocyte arrangement was disordered,and some hepatocyte edema were increased;compared with model group,the liver morphology of the mice in AS-Ⅳ group returned to normal;compared with AS-Ⅳ group,the hepatocyte arrangement of the mice in Compound C+AS-Ⅳ group was disordered and the edges were blurred.The immunohistochemistry results showed that compared with control group,the expression levels of GPX4,FTH1 and FSP1 proteins in liver tissue of the mice in model group were decreased(P<0.05);compared with model group,the expression levels of GPX4,FTH1 and FSP1 proteins in liver tissue of the mice in AS-Ⅳ group were increased(P<0.05);compared with AS-Ⅳ group,the expression levels of GPX4,FTH1 and FSP1 proteins in liver tissue of the mice in Compound C+AS-Ⅳ group were decreased(P<0.05 or P<0.01).The Western blotting results showed that compared with control group,the expression levels of Nrf2,HO-1 and AMPK proteins in liver tissue of the mice in model group were decreased(P<0.01);compared with model group,the expression levels of Nrf2,HO-1 and AMPK proteins in liver tissue of the mice in AS-Ⅳgroup were increased(P<0.01);compared with AS-Ⅳ group,the expression levels of Nrf2,HO-1 and AMPK proteins in liver tissue of the mice in Compound C+AS-Ⅳ group were decreased(P<0.01).Conclusion:AS-Ⅳ can alleviate the CDDP-induced liver injury,and its mechanism may be related to the regulation of AMPK/Nrf2/HO-1 signal pathway and ferroptosis by AS-Ⅳ.
10.The research on effects of transcutaneous electrical acupoint stimulation on muscle strength reserve of calf muscles
Guoning HAN ; Yawen TAO ; Zheng ZHU ; Yingdong WANG ; Mingxing ZHANG ; Qiang XI ; Dan ZHOU ; Yi GUO ; Peng ZHOU ; Xin NIU ; Lin ZHANG ; Jiwen QIU
Space Medicine & Medical Engineering 2025;36(4):356-361
Objective To investigate whether transcutaneous electrical acupoint stimulation(TEAS)can improve the muscle strength,endurance and work efficiency of calf muscles in healthy young men,aiming to explore a new method for preventing and combating microgravity-induced muscle atrophy in space environments.Methods 40 healthy young men aged 18-35 years were randomly divided into a Control group(Pseudo Transcutaneous Electrical Acupoint Stimulation)and a Experimental group(Transcutaneous Electrical Acupoint Stimulation)in a 1∶1 ratio,with 20 participants in each group.In the Control group,the indicator light of the stimulator was covered,and the device was turned on,but the electrodes did not contact the skin,The device automatically turned offafter 3 seconds.In the Experimental group,the TEAS device was connected to the current and TEAS intervention was performed.The electrical stimulation waveform was a sperse-dense wave with a frequency of 4/20 Hz,and the intensity was determined by patient tolerance.The acupoints selected for electrical stimulation in both groups were bilateral Zusanli(ST36)、Liangqiu(ST34),Taixi(KI3),and Fuliu(KI7).Zusanli and Liangqiu were paired,and Taixi and Fuliu were paired.The intervention frequency was 30 min/time,1 time/day,6 days/week,for 2 weeks.The relative peak torque at 60°/s,relative peak torque at 180°/s,and average power at 180°/s of the bilateral calf muscles were measured using an isokinetic dynamometer at 0th,7th,and 14d day of the experiment.Results After 1 week of TEAS,compared with Control group,there were no significant changes in the relative peak torque at 60°/s,relative peak torque at 180°/s and average power at 180°/s of the bilateral anterior calf muscles in the Experimental group(all P>0.05);however,compared with Control group,the relative peak torque at 60°/s and the relative peak torque at 180°/s of the bilateral posterior calf muscles in the Experimental group were significantly increased(all P<0.05).After 2 weeks TEAS;compared with the Control group,there were no significant changes in the relative peak torque at 60°/s,relative peak torque at 180°/s and average power at 180°/s of the bilateral anterior calf muscles in the Experimental group(all P>0.05);however,the relative peak torque at 60°/s,relative peak torque at 180°/s,and average power at 180°/s of the bilateral posterior calf muscles were significantly increased in the Experimental group(all P<0.05).Conclusion TEAS of Zusanli,Liangqiu,Fuliu and Taixi acupoints on the lower limbs for 2 weeks can effectively improve the maximum muscle strength,endurance and work efficiency of the posterior calf muscles in healthy young men.

Result Analysis
Print
Save
E-mail