1.Analysis of related factors for preschool children s safety seat use in a district of Beijing
HU Jiangong, ZHAO Yingying, HE Chao, YOU Kai,PENG Tao
Chinese Journal of School Health 2026;47(1):42-45
Objective:
To understand the allocation and use of safety seats for preschool children and explore its related factors, so as to provide a scientific reference for promoting the usage of safety seats.
Methods:
A stratified random cluster sampling method was used to select 3 143 parents of preschool children aged 3 to 6 from six kindergartens in Shunyi District, Beijing from January 3 to 10, 2022. An online questionnaire survey was conducted to collect and evaluate the equipment and use of child safety seats in different characteristics of preschool children, as well as their scores of health beliefs. Multiple factor Logistic regression analysis was used to investigated the related factors of safety seat configuration and use.
Results:
The equipping rate and usage rate of safety seats for preschool children were 66.56% and 58.45%, respectively. The proportion of equipped and used safety seats for preschool children in core families (69.52%, 62.23%) were higher than that in large families (64.35%, 55.62%), only child families ( 72.39 %, 64.87%) were higher than non only child families (61.49%, 52.86%), and urban families (71.63%, 63.04%) were higher than rural families (52.31%, 45.51%) ( χ 2=9.23, 13.86; 41.72, 46.44; 101.96 ,76.97,all P <0.05) . As the educational level of parents ( χ 2 trend =154.23,98.76) and annual income of the family ( χ 2 trend =155.78,127.69) rised, the reporting rates of the equipped and used child safety seats in the family also increased(all P <0.05 ). There were statistically significant differences in the scores of different dimensions of health beliefs for the provision ( t =-20.22-18.16) and use ( t =24.32-24.17) of safety seats for preschool children(all P <0.05). After adjusting for child sex, child age, family annual income, parental education level, family type, whether the child was an only child, and place of residence,multivariate Logistic regression analysis showed that preschool children with higher perceived susceptibility score( OR =1.11, 1.08), higher self efficacy score( OR =1.23, 1.33), and higher suggestive factors score( OR =1.08, 1.12) were more likely to have and use safety seats in their families, while preschool children with higher perceived impairments score( OR =0.82, 0.80) were less likely to have and use safety seats in their families (all P <0.05).
Conclusions
The installation rate of child safety seats needs to be improved, and there is also a certain gap in their use after installation. Parents of preschool children should improve susceptibility and self efficacy to safety seat equipment and use, and perceptual barriers should be reduced.
2.Survival impact of radiotherapy for patients with de novo metastatic rectal cancer
Harvey Yu-Li SU ; Yun-Hsuan LIN ; Ko-Chao LEE ; Yueh-Ming LIN ; Chun-Chieh HUANG ; Eng-Yen HUANG ; Tai-Jan CHIU ; Shih-Yu HUANG ; Chia-Che WU ; Chang-Ting LIN ; Ming-Chun KUO ; Kai-Lung TSAI
Annals of Coloproctology 2026;42(1):94-102
Purpose:
Metastatic rectal cancer (mRC) is a highly lethal and complex disease that demands a multidisciplinary treatment approach. However, the clinical effectiveness of radiotherapy (RT) for de novo mRC remains controversial and uncertain.
Methods:
This retrospective cohort study examined medical records from Kaohsiung Chang Gung Memorial Hospital for patients with histologically confirmed de novo mRC diagnosed between January 2015 and December 2020. All patients received standard systemic therapy and radical surgery when feasible. The primary outcome, overall survival (OS), was assessed using the Kaplan-Meier method. Multivariable analysis was performed using a Cox regression model.
Results:
Among 271 patients included in the analysis, 117 received RT and 154 did not. The median OS was significantly longer in the RT group compared with the non-RT group (27.8 months vs. 21.9 months; P=0.046). Multivariate analysis identified several independent predictors of OS: age ≥65 years (hazard ratio [HR], 1.69; 95% confidence interval [CI], 1.26–2.27; P=0.001), primary tumor resection (HR, 2.62; 95% CI, 1.90–3.61; P<0.001), M1b or M1c disease (HR, 1.97; 95% CI, 1.44–2.69; P<0.001), and receipt of RT (HR, 1.41; 95% CI, 1.02–1.94; P=0.036).
Conclusion
RT significantly improves OS in patients with mRC, underscoring its role in treatment strategies. These findings support its inclusion in therapeutic protocols and highlight the need for larger, multicenter trials to confirm and extend these results.
3.Pre-operative risk assessment of hepatocellular carcinoma recurrence in liver transplant recipients by non-invasive detection of pre-existing genetic lesions
Suqin YANG ; Sunbin LING ; Jianhua LI ; Yan WANG ; Jiapei WANG ; Qiwei HUANG ; Fanming LIU ; Yiqi ZHUANG ; Yingyu ZHENG ; Rui WANG ; Zhe YANG ; Xiaoping ZHENG ; Kai WANG ; Zhikun LIU ; Jun CHEN ; Jianguo WANG ; Haiyang XIE ; Lin ZHOU ; Leiming CHEN ; Guoqiang CAO ; Dandan CHEN ; Junfang JI ; Bin ZHAO ; Chao JIANG ; Di LU ; Xuyong WEI ; Hangjin JIANG ; Qiaonan SHAN ; Hengbo SHI ; Yong-Zhen XU ; Shusen ZHENG ; Zhengxin WANG ; Shengda LIN ; Xiao XU
Clinical and Molecular Hepatology 2026;32(2):884-903
Background/Aims:
Liver transplantation (LT) following total hepatectomy is a life-saving treatment for hepatocellular carcinoma (HCC). The HCC recurrence after LT hinders the effectiveness of the procedure. The objective of this study is to develop a pre-operative risk stratification model based on a liquid biopsy.
Methods:
We conducted a comprehensive multi-omics study of 260 HCC patients from three centers, including clinical data, low-coverage whole-genome sequencing of cell-free DNA (cfDNA) from plasma, as well as whole-exome, single-nucleus RNA, and spatial transcriptomics from matched tumor and non-tumor tissues.
Results:
We identified cfDNA-derived copy number alteration (CNA) signatures associated with post-transplant recurrence. By integrating cfDNA-derived CNA profiles with single-cell transcriptomic data, we traced recurrence-associated cfDNA to a distinct subpopulation of malignant cells within the primary tumor. These cells were embedded in a pro-metastatic microenvironment of specialized endothelial subtypes and cancer-associated fibroblasts. Notably, most recurrence-associated lesions were detectable in cfDNA prior to liver transplantation (LT). Building on these insights, we developed the ZJU Criteria based on CNA fragments and tumor markers, a pre-LT risk prediction tool that integrates conventional clinical factors with cfDNA-derived CNA signatures, and validated it using internal and independent external cohorts.
Conclusion
Our findings suggest that post-transplant recurrence commonly originates from advanced subclones that emerge late during tumor evolution. The ZJU Criteria provides an accurate, non-invasive strategy that significantly improves pre-LT risk stratification and clinical decision-making for patients with HCC.
4.Using of Lawnest,an intravascular snare in retrograde percutaneous coronary intervention for chronic total occlusion:a case report
Ying-kai LI ; Song-yuan HE ; Zi-chao CHENG ; Hong-yu PENG
Chinese Journal of Interventional Cardiology 2025;33(11):657-660
Coronary chronic total occlusion(CTO)remains a significant challenge in the field of interventional therapy for coronary artery disease.With advancements in interventional techniques,particularly retrograde approaches,the success rate of CTO interventions has improved.The key steps of retrograde intervention include traversing collateral channels with the retrograde guidewire,wiring the occlusion segment,and establishing antegrade access.In this case,the patient had a heavily calcified occlusion at the left circumflex artery(LCX)ostium jailed by the prior stent implanted in the left main and anterior descending arteries,making it difficult to establish antegrade access using conventional methods after retrograde guidewire crossing.The procedure was successfully completed by employing a domestically developed intravascular snare system combined with a pre-assembled extension catheter technique to capture the retrograde guidewire and establish antegrade access,followed by stent implantation at the LCX ostium.This innovative approach provides a new strategy for complex CTO retrograde interventions,particularly in cases where retrograde guidewire entry into the antegrade guiding catheter is challenging.
5.Screening and validation of glucose metabolism genes in osteoarthritis
Kexin LIU ; Chao MA ; Kai LIU ; Maochen HAO ; Xingru WANG ; Lingting MENG ; Mei DONG ; Jianzhong WANG
Chinese Journal of Tissue Engineering Research 2025;29(20):4181-4189
BACKGROUND:Glucose metabolism plays a crucial role in maintaining the normal physiological function of the body.Glucose metabolism disorder can lead to a range of health problems.At present,the molecular mechanism of glucose metabolism and potential gene targets in osteoarthritis need to be further studied.OBJECTIVE:To analyze the genes related to glucose metabolism in osteoarthritis by bioinformatics methods,and to verify them by cell experiments in vitro,so as to provide new ideas for prevention and treatment of osteoarthritis from the perspective of glucose metabolism.METHODS:Differentially expressed genes and glucose metabolism related genes were screened out from GEO database and GeneCards database.The genes related to both osteoarthritis and glucose metabolism were obtained.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis were used to screen the functions and pathways of these genes.To further investigate the interactions between these genes,a protein-protein interaction network was constructed and computational methods using Cytoscape software were utilized to identify key genes(Hub genes)for osteoarthritis glucose metabolism.In addition,CIBERSORT algorithm was used to analyze immune cell infiltration in GSE98918 data set.Finally,the expression of Hub gene was verified by cell experiment in vitro.RESULTS AND CONCLUSION:A total of 134 osteoarthritis glucose metabolism-related genes were obtained.GO enrichment analysis showed that GO was mainly involved in the reaction of toxic substances,the positive regulation of inflammatory reaction,the reaction of lipopolysaccharide and so on.KEGG enrichment analysis showed that it was closely related to PI3K-Akt signaling pathway,interleukin-17 signaling pathway,and AGE-RAGE signaling pathway in diabetic complications.Macrophages,monocytes,resting natural killer cells,regulatory T cells,and CD8+T cells were the main infiltrating cells obtained by immune infiltration analysis.In vitro cell experiments showed that the expression of Hub genes SERPINF1,TAC1,GLUL,APOE,and TMEM176A in the experimental group was significantly different from that in the control group.The mRNA expression of HLA-DRA was not statistically significant.The results show that SERPINF1,TAC1,Glul,APOE,and TMEM176A may be the key genes of glucose metabolism in osteoarthritis,and may be potential new targets for the prevention and treatment of osteoarthritis.
6.Study on interactive training and learning of residents in the department of radiology based on breast MR BI-RADS
Yuan JI ; Deshuo DONG ; Lina ZHANG ; Chao YANG ; Lijun WANG ; Yuanfei LI ; Yueqi WU ; Kai WANG
Chinese Journal of Medical Education Research 2025;24(8):1092-1097
Objective:To evaluate the application value of interactive learning in enhancing the diagnosis of breast cancer by residents in the department of radiology through training based on the interpretation of breast magnetic resonance imaging (MRI) features by the breast imaging reporting and data system (BI-RADS).Methods:A total of 23 trainees completed BI-RADS standardized reports of 250 cases. These cases were divided into a pre-training group (Group 1) and post-training groups (initial training, Groups 2-4; advanced training, Groups 5-6), forming a total of six groups. The efficacy of interactive learning through course lectures and case-based practice in enhancing their ability in breast cancer diagnosis was analyzed. All trainees generated reports based on the BI-RADS scoring criteria. Interpretation agreement rates, evaluation time, and confidence levels were recorded. SPSS 25.0 was used for independent samples t test, chi-square test, and rank-sum test. Results:During the initial stage of training, the agreement rate of 150 cases reached 80.00%, which was recommended as the endpoint for completion of the initial learning phase. A significant difference existed between Group 4 and Group 1 ( P=0.012) in agreement rate. Statistically significant differences were noted in evaluation time for Groups 5 and 6 before and after advanced training ( P=0.001 and 0.007, respectively). A significant difference in confidence level was observed for Group 5 ( P=0.005). Conclusions:Interactive training based on BI-RADS standardized reporting can improve the diagnosis of breast diseases by residents in the department of radiology, particularly for enhancing the quality of reports for mass-like enhancement breast diseases.
7.Screening and validation of glucose metabolism genes in osteoarthritis
Kexin LIU ; Chao MA ; Kai LIU ; Maochen HAO ; Xingru WANG ; Lingting MENG ; Mei DONG ; Jianzhong WANG
Chinese Journal of Tissue Engineering Research 2025;29(20):4181-4189
BACKGROUND:Glucose metabolism plays a crucial role in maintaining the normal physiological function of the body.Glucose metabolism disorder can lead to a range of health problems.At present,the molecular mechanism of glucose metabolism and potential gene targets in osteoarthritis need to be further studied.OBJECTIVE:To analyze the genes related to glucose metabolism in osteoarthritis by bioinformatics methods,and to verify them by cell experiments in vitro,so as to provide new ideas for prevention and treatment of osteoarthritis from the perspective of glucose metabolism.METHODS:Differentially expressed genes and glucose metabolism related genes were screened out from GEO database and GeneCards database.The genes related to both osteoarthritis and glucose metabolism were obtained.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis were used to screen the functions and pathways of these genes.To further investigate the interactions between these genes,a protein-protein interaction network was constructed and computational methods using Cytoscape software were utilized to identify key genes(Hub genes)for osteoarthritis glucose metabolism.In addition,CIBERSORT algorithm was used to analyze immune cell infiltration in GSE98918 data set.Finally,the expression of Hub gene was verified by cell experiment in vitro.RESULTS AND CONCLUSION:A total of 134 osteoarthritis glucose metabolism-related genes were obtained.GO enrichment analysis showed that GO was mainly involved in the reaction of toxic substances,the positive regulation of inflammatory reaction,the reaction of lipopolysaccharide and so on.KEGG enrichment analysis showed that it was closely related to PI3K-Akt signaling pathway,interleukin-17 signaling pathway,and AGE-RAGE signaling pathway in diabetic complications.Macrophages,monocytes,resting natural killer cells,regulatory T cells,and CD8+T cells were the main infiltrating cells obtained by immune infiltration analysis.In vitro cell experiments showed that the expression of Hub genes SERPINF1,TAC1,GLUL,APOE,and TMEM176A in the experimental group was significantly different from that in the control group.The mRNA expression of HLA-DRA was not statistically significant.The results show that SERPINF1,TAC1,Glul,APOE,and TMEM176A may be the key genes of glucose metabolism in osteoarthritis,and may be potential new targets for the prevention and treatment of osteoarthritis.
8.Bioinformatics screening of key genes for endoplasmic reticulum stress in osteoarthritis and experimental validation
Maochen HAO ; Chao MA ; Kai LIU ; Kexin LIU ; Lingting MENG ; Xingru WANG ; Jianzhong WANG
Chinese Journal of Tissue Engineering Research 2025;29(26):5632-5641
BACKGROUND:Endoplasmic reticulum stress is closely associated with the occurrence and progression of osteoarthritis,but the key genes and regulatory mechanisms remain unclear.OBJECTIVE:Utilizing bioinformatics to identify crucial endoplasmic reticulum stress-related genes in osteoarthritis,followed by experimental validation in cell models,aiming to offer new strategies for the prevention and treatment of osteoarthritis from the perspective of endoplasmic reticulum stress.METHODS:Osteoarthritis-related dataset GSE55235 was downloaded from the GEO database.Differential genes in synovial tissue of osteoarthritis were obtained through WGCNA machine learning algorithm and intersected with endoplasmic reticulum stress-related genes from the GeneCard database to acquire differential endoplasmic reticulum stress-related genes in osteoarthritis(ERSDEGs).These genes underwent GO and KEGG enrichment analysis,construction of a protein-protein interaction network,and validation of diagnostic efficiency in external datasets.Human primary synovioblast model of osteoarthritis was constructed.The control group was not treated,and the experimental group received 20 ng/mL lipopolysaccharide to simulate osteoarthritic synoviocyte modeling.Real-time fluorescence quantitative PCR was then performed to validate the expression level of each differential gene followed by immune infiltration analysis.RESULTS AND CONCLUSION:A total of 27 key endoplasmic reticulum stress-related genes in osteoarthritis were identified.GO enrichment analysis revealed that these genes were mainly enriched in collagen metabolism,chemokine,antigen binding,and immunoglobulin receptor binding processes.KEGG analysis indicated that they were mainly enriched in pathways such as rheumatoid arthritis and relaxin signaling pathways.The protein-protein interaction network was constructed,and the top five genes with the highest scores were identified using the Degree algorithm in Cytoscape software,including matrix metallopeptidase 1,tumor necrosis factor ligand superfamily member 11,matrix metallopeptidase 9,collagen type 1 alpha 1,and chemokine C-X-C motif ligand 12.Immune infiltration analysis showed that immune cells were mainly distributed in M2 macrophages,chemokine C-X-C motif ligand 12 showed a significant positive correlation with resting mast cells(r=0.70,P<0.001)and a significant negative correlation with resting memory CD4+T cells(r=-0.72,P<0.001).Matrix metallopeptidase 9 showed a significant positive correlation with MO macrophages(r=0.94,P<0.001).Collagen type 1 alpha 1 was significantly positively correlated with resting NK cells(r=0.77,P<0.001)and MO macrophages(r=0.76,P<0.001).Receiver operator characteristic curve analysis in external datasets GSE77298 and GSE1919 showed that the five key genes had good disease prediction value.In vitro cell experiments demonstrated significant differences in the expression levels of matrix metallopeptidase 1,tumor necrosis factor ligand superfamily member 11,matrix metallopeptidase 9,and chemokine C-X-C motif ligand 12 in the osteoarthritic cell model compared to the control group.These results showed that the key genes related to endoplasmic reticulum stress in osteoarthritis,including matrix metallopeptidase 1,tumor necrosis factor ligand superfamily member 11,matrix metallopeptidase 9,and chemokine C-X-C motif ligand 12,influence the occurrence and development of osteoarthritis through the links of collagen degradation and immune regulation,which are expected to provide new insights into the targeted treatment of osteoarthritis.
9.Relationship between the expression of serum lncRNA XIST and miR-126-3p in non-small cell lung cancer and recurrence after radical surgery
Kai SU ; Qing-hua YU ; Jia-wang CAO ; Shou-zhuo LI ; Chao ZENG
Journal of Regional Anatomy and Operative Surgery 2025;34(2):134-139
Objective To investigate the expression of serum long non-coding RNA X-inactive specific transcript(lncRNA XIST)and microRNA-126-3p(miR-126-3p)in patients with non-small cell lung cancer(NSCLC),and their relationship with recurrence after radical surgery.Methods A total of 108 NSCLC patients who underwent radical surgery and were admitted to General Hospital of Southern Theater Command of the People's Liberation Army of China from February 2019 to October 2020 were selected as the NSCLC group,and 52 healthy volunteers who underwent physical examination in this hospital were selected as the control group.qRT-PCR method was used to detect the relative expression levels of serum lncRNA XIST and miR-126-3p.Pearson method was used to analyze the correlation between serum lncRNA XIST and miR-126-3p expression.Logistic regression analysis was used to analyze the influencing factors of postoperative recurrence in NSCLC patients.Receiver operating characteristic(ROC)curve was used to evaluate the predictive value of serum lncRNA XIST and miR-126-3p on postoperative recurrence in patients.Results The expression level of serum lncRNA XIST in the NSCLC group was higher than that in the control group(P<0.05),while the expression level of miR-126-3p was lower than that in the control group(P<0.05).The expression levels of serum lncRNA XIST and miR-126-3p were related to TNM staging and lymph node metastasis(P<0.05).Bioinformatics website predicted that there was a targeted binding site between lncRNA XIST and miR-126-3p,and serum lncRNA XIST was negatively correlated with miR-126-3p expression(r=-0.579,P<0.05).Compared with the non-recurrent group,the expression level of serum lncRNA XIST in the recurrent group increased(P<0.05),while the expression level of miR-126-3p in the recurrent group decreased(P<0.05).Logistic regression analysis results showed that lncRNA XIST,miR-126-3p,lymph node metastasis,and TNM staging were the influencing factors for postoperative recurrence in NSCLC patients(P<0.05).The area under the curve(AUC)of serum lncRNA XIST,miR-126-3p,and the combination of the two in prediction of postoperative recurrence in NSCLC patients were 0.750,0.886,and 0.933,respectively,the combined prediction of the two was superior to individual prediction(Zcombination vs.lncRNA XIST=4.076,Zcombination vs.miR-126-3p=2.065,P<0.05).Conclusion The expression of serum lncRNA XIST is increased and miR-126-3p is decreased in NSCLC patients,both of which have certain predictive value for recurrence after radical surgery in patients.
10.Comparison of efficacy and safety of transurethral thulium fiber laser enucleation of prostate in patients with different prostate volumes
Chao ZUO ; Guoli WANG ; Kunlin YANG ; Xinyan CHE ; Yisen MENG ; Kai ZHANG
Journal of Peking University(Health Sciences) 2025;57(4):711-716
Objective:To evaluate the effectiveness and safety of thulium fiber laser enucleation of the prostate(ThuFLEP)in the treatment of oversized(>200 mL)prostate.Methods:Clinical data of 475 benign prostatic hyperplasia(BPH)patients operated by the same urologist at Peking University First Hospital from January 2022 to May 2024 were retrospectively analyzed,all of whom were treated with thu-lium fiber laser,and the patients were divided into three groups according to the total volume of the pros-tate(TPV):group A(TPV<100 mL),group B(100 mL≤TPV<200 mL),and group C(TPV ≥200 mL).The age of the patients in the three groups[(69.38±7.79)years,(69.64±8.69)years,(70.32±7.44)years],International Prostate Symptom Score(IPSS)[(22.7±1.9),(22.8±2.7),(25.8±3.7)],and the maximum urinary flow rate(Qmax)[(7.9±2.7)mL/s,(9.3±4.3)mL/s,(9.9±3.3)mL/s]were not statistically significant(P>0.05).The prostate volume in the three groups[(103.49±46.19)mL,(75.73±30.69)mL,(273.49±49.19)mL]and prostate specific antigen(PSA)[3.52(1.05,8.76)μg/L,6.78(1.61,7.45)μg/L,8.52(5.05,12.76)μg/L]were statistically significant(P<0.05).Results:All surgeries were successfully completed.The dif-ferences in enucleation time[30.0(21.2,44.5)min,41.6(31.2,52.5)min,45.1(35.2,50.0)min]and hospitalization time[(6.06±1.21)d,(6.15±1.50)d,(7.71±1.74)d]among the three groups were not statistically significant(P>0.05);and the differences in the postoperative in-dwelling catheter time[(4.0±1.4)d,(4.0±1.3)d,(6.6±1.1)d],operative time[61(42,89)min,82(62,105)min,115(96,142)min],enucleation efficiency[1.29(0.71,1.56)g/min,1.67(1.23,2.15)g/min,2.74(2.20,3.34)g/min],and hemoglobin drop values[12(7,19)g/L,17(11,24)g/L,27(19,35)g/L]were statistically different(P<0.05).Linear regression ana-lysis was used to show a strong positive linear correlation between enucleation efficiency and enucleation weight(r=0.880,P<0.001),and the enucleation efficiency increased with the increase of prostate volume.The differences in IPSS[(6.6±1.7),(6.2±1.4),(4.6±1.1)]and Qmax[(18.9±3.1)mL/s,(16.8±3.8)mL/s,(22.9±7.1)mL/s]were not statistically significant among the three groups(P>0.05),and the differences in IPSS and Qmax were statistically significant compared with those before surgery.The differences were statistically significant in preoperative comparisons,but the postoperative urinary flow rate of group C increased significantly more than the remaining two groups in terms of Qmax(P<0.05).The patients in the three groups were followed up for 3 months,and post-operative complications were categorized into Clavien-Dindo Ⅰ(urinary retention,persistent hematu-ria),Clavien-Dindo Ⅱ(glandular remnants,urinary tract infection,blood transfusion)and Clavien-Dindo Ⅲ(urethral stenosis,contracture of the bladder neck,and reoperation for hemorrhage)based on the Clavien-Dindo Complications System score,the incidence of Clavien-Dindo in the three groups was 5.2%(13 cases),6.7%(12 cases)and 12.1%(7 cases),respectively,with statistically significant differences(P<0.05);among them,there were statistically significant differences in urinary infection,blood transfusion and bleeding reoperation(P<0.05),and there was no statistically significant difference in the remaining complications(P>0.05).Conclusion:The risk of blood transfusion and re-hemostasis increases with larger prostate volume,the efficiency of enucleation increases with the increase of prostate vo-lume,and thulium fiber laser prostate enucleation is safe and effective in the treatment of large-volume BPH.


Result Analysis
Print
Save
E-mail