Objective： To compare the effect of neoadjuvant chemotherapy （NACT） with adjuvant chemotherapy （ACT） using oxaliplatin plus S-1 （sex） or capecitabine （CapeOX） on gastric cancer patients with D2 lymphadenectom...Objective： To compare the effect of neoadjuvant chemotherapy （NACT） with adjuvant chemotherapy （ACT） using oxaliplatin plus S-1 （sex） or capecitabine （CapeOX） on gastric cancer patients with D2 lymphadenectomy. Methods： This was a two-by-two factorial randomized phase Ⅱ-Ⅲ trial, and registered on ISRCTN registry （No. ISRCTN12206108）. Locally advanced gastric cancer patients were randomized to neoadjuvant sex, neoadjuvant CapeOX, adjuvant sex, or adjuvant CapeOX arms. Primary analysis was performed on an intention- to-treat （ITT） basis using overall survival （OS） as primary endpoint. Results： This trial started in September 2011 and closed in December 2012 with 100 patients enrolled. Treatment completion rate was 56%, 52%, 38% and 30% in the four arms, respectively. NACT group had fewer dropouts due to unacceptable toxicity （P=0.042）. Surgical complication rate did not differ by the four groups （P=0.986）. No survival signifcant difference was found comparing NACT with ACT （P=0.664; 5-year-OS： 70% vs. 74% respectively）, nor between the sex and CapeOX groups （P=0.252; 5-year-OS： 78% vs. 66% respectively）. Subgroup analysis showed sex significantly improved survival in patents with diffuse type （P=0.048）. Conclusions： No significant survival difference was found between NACT and ACT. sex and CapeOX had good safety and efficacy as neoadjuvant regimens. Diffuse type patients may survive longer due to sex.展开更多
Objective： To determine the capability of dynamic enhanced computed tomography（CT） to differentiate liver metastases（LMs） of well-differentiated from poorly-differentiated gastroenteropancreatic neuroendocrine ne...Objective： To determine the capability of dynamic enhanced computed tomography（CT） to differentiate liver metastases（LMs） of well-differentiated from poorly-differentiated gastroenteropancreatic neuroendocrine neoplasms（GEP-NENs）.Methods： Patients with LMs of GEP-NENs who underwent dynamic enhanced CT examination in Peking University Cancer Hospital from January 2009 to October 2015 were included and data were retrospectively analyzed. We assessed the qualitative and quantitative CT features to identify the significant differentiating CT features of LMs of poorly-differentiated GEP-NENs from those of well-differentiated GEP-NENs using univariate analysis and a multivariate logistic regression model.Results： The study included 22 patients with LMs of well-differentiated GEP-NENs and 32 patients with LMs of poorly-differentiated GEP-NENs. Univariate analysis revealed statistically significant differences between the LMs of well-and poorly-differentiated GEP-NENs in terms of feeding arteries（36.4% vs. 75.0%, χ2=8.061,P=0.005）, intratumoral neovascularity（18.2% vs. 59.4%, χ2=9.047, P=0.003）, lymphadenopathy（27.3% vs. 81.2%,χ2=15.733, P〈0.001）, tumor-to-aortic ratio in the hepatic arterial and portal venous phase（T-A/AP： 0.297±0.080 vs.0.251±0.059, t=2.437, P=0.018; T-A/PVP： 0.639±0.138 vs. 0.529±0.117, t=3.163, P=0.003） and tumor-to-liver ratio in the hepatic arterial phase（T-L/AP： 1.108±0.267 vs. 0.907±0.240, t=2.882, P=0.006）. The LMs of poorlydifferentiated GEP-NENs showed more feeding arteries, more intratumoral neovascularity, more lymphadenopathy and a lower tumor-to-aortic ratio. Multivariate analysis suggested that intratumoral neovascularity [P=0.015, OR=0.108, 95% confidence interval（95% CI）, 0.018–0.646], lymphadenopathy（P=0.001,OR=0.055, 95% CI, 0.009–0.323） and T-A/PVP（P=0.004, OR=5.3 E–5, 95% CI, 0.000–0.044） were independent factors for differentiating LMs of poorly-differentiated from well-differentiated GEP-NENs.Conclusions： Dynamic enhanced CT features（intratumoral neovascularity, lymphadenopathy and T-A/PVP）are useful in the pathological classification of LMs of GEP-NENs.展开更多
胃肝样腺癌(hepatoid adenocarcinoma of stomach,HAS)是一种特殊类型的胃癌。其发病率不高,但由于HAS具有高度侵袭性的生物学行为,容易发生淋巴转移及肝转移,预后较差,受到临床广泛关注。随着HAS临床病理特征、预后以及分子生物学特征...胃肝样腺癌(hepatoid adenocarcinoma of stomach,HAS)是一种特殊类型的胃癌。其发病率不高,但由于HAS具有高度侵袭性的生物学行为,容易发生淋巴转移及肝转移,预后较差,受到临床广泛关注。随着HAS临床病理特征、预后以及分子生物学特征等的持续研究,关于HAS的认识正不断深入。然而,目前在HAS研究领域仍存在一些容易被忽视并亟需解决的问题。本文梳理既往关于HAS的病例报道及研究,在HAS的范畴、起源、诊断方法、分子生物学特征及预后等方面进行总结和探讨,以期为HAS的后续研究提供一定方向。展开更多
Objective:To explore the intraperitoneal free cancer cell(IFCC)detection value of negative enrichment and immune fluorescence in situ hybridization(NEimFISH)on chromosomes(CEN)8/17.Methods:To verify the reliability of...Objective:To explore the intraperitoneal free cancer cell(IFCC)detection value of negative enrichment and immune fluorescence in situ hybridization(NEimFISH)on chromosomes(CEN)8/17.Methods:To verify the reliability of NEimFISH,29 gastric cancer tumors,their adjacent tissues and greater omental tissues were tested.Our study then included 105 gastric cancer patients for IFCC.We defined patients as IFCC-positive if a signal was detected,regardless of the detailed cancer cell numbers.A comparison of clinicopathological features was conducted among IFCC groups.We also compared the diagnosis value and peritoneal recurrence predictive value among different detection methods.The comparison of IFCC number was also conducted among different groups.Results:A cutoff of 2.5 positive cells could distinguish all benign tissue samples and 97%of malignant tissue samples in our study.Compared to intestinal gastric cancer,patients with diffuse gastric cancer tended to have more IFCCs(6 vs.4,P=0.002).The IFCC counts were often higher in the lymphovascular invasion positive group than negative group(3 vs.1,P=0.022).All IFCC samples that were considered positive using conventional cytology were also found to be positive using NEimFISH.When compared to conventional cytology and paraffin pathology,NEimFISH had a higher IFCC positive rate(68.9%)and higher one-year peritoneal recurrence predictive value with area under the curve(AUC)of 0.922.Conclusions:Gastric cancer could be effectively diagnosed by NEimFISH.The IFCC number found using NEimFISH on CEN8/17 is closely associated with Lauren type and vascular invasion of cancer.NEimFISH is a reliable detection modality with a higher positive detection rate,higher one-year peritoneal recurrence predictive value and quantitative features for IFCC of gastric cancer.展开更多
Objective:The accurate prediction of tumor response to neoadjuvant chemoradiotherapy(nCRT)remains challenging.Few studies have investigated pathologic complete response(ypCR)prediction in patients with residual flat m...Objective:The accurate prediction of tumor response to neoadjuvant chemoradiotherapy(nCRT)remains challenging.Few studies have investigated pathologic complete response(ypCR)prediction in patients with residual flat mucosal lesions after treatment.This study aimed to identify variables for predicting ypCR in patients with residual flat mucosal lesions after nCRT for locally advanced rectal cancer(LARC).Methods:Data of patients with residual flat mucosal lesions after nCRT who underwent radical resection between 2009 and 2015 were retrospectively collected from the LARC database at Peking University Cancer Hospital.Univariate and multivariate analyses of the association between clinicopathological factors and ypCR were performed,and a nomogram was constructed by incorporating the significant predictors.Results:Of the 246 patients with residual flat mucosal lesions included in the final analysis,56(22.8%)had ypCR.Univariate and multivariate analyses showed that pretreatment cT stage(pre-cT)≤T2(P=0.016),magnetic resonance tumor regression grade(MR-TRG)1-3(P=0.001)and residual mucosal lesion depth=0 mm(P<0.001)were associated with a higher rate of ypCR.A nomogram was developed with a concordance index(C-index)of0.759 and the calibration curve showed that the nomogram model had good predictive consistency.The follow-up time ranged from 3.0 to 113.3 months,with a median follow-up time of 63.77 months.The multivariate Cox regression model showed that the four variables in the nomogram model were not risk factors for disease-free survival(DFS)or overall survival(OS).Conclusions:Completely flat mucosa,early cT stage and good MR-TRG were predictive factors for ypCR instead of DFS or OS in patients with LARC with residual flat mucosal lesions after nCRT.Endoscopic mucosal re-evaluation before surgery is important,as it may contribute to decision-making and facilitate nonoperative management or organ preservation.展开更多
Objective: The present study investigated the prognosis value of preoperative fluorodeoxyglucose(FDG)positron emission tomography/computed tomography(PET/CT) in patients with local advanced gastric cancer(LAGC).Method...Objective: The present study investigated the prognosis value of preoperative fluorodeoxyglucose(FDG)positron emission tomography/computed tomography(PET/CT) in patients with local advanced gastric cancer(LAGC).Methods: In total, 144 patients [median age 63(range: 48-80) years old] with LAGC underwent 18 F-FDG PET/CT prior to any treatment. The maximum standardized uptake values(SUVmax), mean standardized uptake values(SUVmean), metabolic tumor volume(MTV) and total lesion glycolysis(TLG) of the primary lesion were measured on PET/CT and correlated with clinicopathological features and survival.Results: Significant differences in SUVmean, SUVmax, MTV and TLG were found according to Lauren’s classification, histologic grade and T category(P<0.05). During the 26.5-month follow-up, 51(35.4%) patients died and 70(48.6%) exhibited disease progression. The optimal thresholds of MTV and TLG were 15.1 cm^3 and 47.3 cm^3, respectively. The 3-year progression-free survival(PFS) and overall survival(OS) for patients with high TLG values were 30% and 38% compared to 38% and 47% for low TLG values, respectively(P<0.05). Univariate and multifactor analyses demonstrated that lymph node metastasis and T stage were independent prognostic factors for PFS;T stage, histologic grade and TLG were independent prognostic factors for OS(P<0.05). Molecular markers had no relationship with patient’s outcomes.Conclusions: Metabolic activity of primary gastric tumors from 18 F-FDG PET/CT is a prognostic factor in patients with LAGC.展开更多
Objective:Fluoroscopy guidance is generally required for endobronchial ultrasonography with guide sheath(EBUS-GS)in peripheral pulmonary lesions(PPLs).Virtual bronchoscopic navigation(VBN)can guide the bronchoscope by...Objective:Fluoroscopy guidance is generally required for endobronchial ultrasonography with guide sheath(EBUS-GS)in peripheral pulmonary lesions(PPLs).Virtual bronchoscopic navigation(VBN)can guide the bronchoscope by creating virtual images of the bronchial route to the lesion.The diagnostic yield and safety profiles of VBN without fluoroscopy for PPLs have not been evaluated in inexperienced pulmonologist performing EBUS-GS.Methods:Between January 2016 and June 2017,consecutive patients with PPLs referred for EBUS-GS at a single cancer center were enrolled.The diagnostic yield as well as safety profiles was retrospectively analyzed,and our preliminary experience was shared.Results:A total of 109 patients with 109 lesions were included,99(90.8%)lesions were visible on EBUS imaging.According to the procedure time needed to locate the lesion on EBUS,24.8%(27/109)were deemed technically difficult procedures;however,no significant relationships were identified between candidate parameters and technically difficult procedures.The overall diagnosis yield was 74.3%(81/109),and the diagnostic yield of malignancy was 83.7%(77/92).Lesions larger than 20 mm[odds ratio(OR),2.758;95%confidence interval(95%CI),1.077-7.062;P=0.034]and probe of within type(OR,3.174;95%CI,1.151-8.757,P=0.026)were independent factors leading to a better diagnostic yield in multivariate analysis.About 30 practice procedures were needed to achieve a stable diagnostic yield,and the proportion of technically difficult procedures decreased and stabilized after 70 practice procedures.Regarding complications,one patient(0.9%)had intraoperative hemorrhage(100 mL)which was managed under endoscopy.Conclusions:VBN without fluoroscopy guidance is still useful and safe for PPLs diagnosis,especially for malignant diseases when performed by pulmonologist without previous experience of EBUS-GS.VBN may simplify the process of lesion positioning and further multi-center randomized studies are warranted.展开更多
Objective:To explore the correlation between computed tomography(CT)features and combined positive score(CPS)of programmed cell death ligand 1(PD-L1)expression in patients with gastric cancer(GC).Methods:This study re...Objective:To explore the correlation between computed tomography(CT)features and combined positive score(CPS)of programmed cell death ligand 1(PD-L1)expression in patients with gastric cancer(GC).Methods:This study reviewed an institutional database of patients who underwent GC operation without neoadjuvant chemotherapy between December 2019 and September 2020.The CPS results of PD-L1 expression of postoperative histological examination were recorded by pathology.Baseline CT features were measured,and their correlation with CPS 5 or 10 score groups of PD-L1 expression was analyzed.Results:Data for 153 patients with GC were collected.Among them,124 were advanced GC patients,and 29were early GC patients.None of the CT features significantly differed between CPS groups with a cutoff score of 5and a score of 10 in patients with early GC.In advanced GC,the presence of lymph nodes with short diameters>10mm was significantly different(P=0.024)between the CPS<5 and CPS≥5 groups.CT features such as tumor attenuation in the arterial phase,long and short diameter of the largest lymph node,the sum of long diameter of the two largest lymph nodes,the sum of short diameter of the two largest lymph nodes,and the presence of lymph nodes with short diameters>10 mm significantly differed between the CPS<10 and CPS≥10 groups in advanced GC.The sensitivity,specificity and area under receiver operating characteristic(ROC)curve of logistic regression model for predicting CPS≥10 was 71.7%,50.0%and 0.671,respectively.Microsatellite instability(MSI)status was significantly different in CPS groups with cutoff score of 5 and 10 in advanced GC patients.Conclusions:CT findings of advanced GC patients with CPS≥10 showed greater arterial phase enhancement and larger lymph nodes.CT has the potential to help screen patients suitable for immunotherapy.展开更多
Dear Editor,Extramammary Paget disease(EMPD)is a rare adenocarcinoma that originates in the apocrine gland-rich skin and usually affects the perineal skin(primary EMPD)or represents the intraepithelial spread of an un...Dear Editor,Extramammary Paget disease(EMPD)is a rare adenocarcinoma that originates in the apocrine gland-rich skin and usually affects the perineal skin(primary EMPD)or represents the intraepithelial spread of an underlying visceral carcinoma(secondary EMPD).Approximately half of EMPD cases are confined to the epidermis,which was defined as intraepithelial EMPD.展开更多
The BRAF gene is an important signaling molecule in human cells that is involved in the regulation of cell growth,differentiation,and survival.When the BRAF gene mutates,it can lead to abnormal activation of the signa...The BRAF gene is an important signaling molecule in human cells that is involved in the regulation of cell growth,differentiation,and survival.When the BRAF gene mutates,it can lead to abnormal activation of the signaling pathway,which promotes cell proliferation,inhibits cell apoptosis,and ultimately contributes to the occurrence and development of cancer.BRAF mutations are widely present in various cancers,including malignant melanoma,thyroid cancer,colorectal cancer,non-small cell lung cancer,and hairy cell leukemia,among others.BRAF is an important target for the treatment of various solid tumors,and targeted combination therapies,represented by BRAF inhibitors,have become one of the main treatment modalities for a variety of BRAF-mutation-positive solid tumors.展开更多
Neoadjuvant PD-1 inhibitor is promising in cutaneous melanoma but remains unknown in acral melanoma(AM).This phase Ib trial study(Clinicaltrials.gov NCT04197882)assessed the efficacy and safety of the combination of n...Neoadjuvant PD-1 inhibitor is promising in cutaneous melanoma but remains unknown in acral melanoma(AM).This phase Ib trial study(Clinicaltrials.gov NCT04197882)assessed the efficacy and safety of the combination of neoadjuvant oncolytic virus orienX010(ori)and anti-PD-1 toripalimab(tori)for resectable AM.Thirty patients of stage III/IV received neoadjuvant therapy of ori and tori for 12 weeks before surgery,followed by adjuvant treatment with tori for 1 year.Primary endpoints were radiographic and pathological response rates,with secondary endpoints of 1-and 2-year recurrence-free survival(RFS)rates,event-free survival(EFS)rates,and safety.Twenty-seven completed surgery and tori adjuvant treatment and median follow-up was 35.7 months.Radiographic and pathological response rates were 36.7%and 77.8%,with complete response rates of 3.3%and 14.8%,1-and 2-year RFS rates of 85.2%and 81.5%,and 1-and 2-year EFS rates of 83%and 73%,respectively.Adverse events occurred in all patients,mainly grade 1-2.There was no correlation between PET/CT evaluation and pathological response or progression-free survival/overall survival.Patients with pathological response showed tumor beds with high tertiary lymphoid structures(TLSs)and tumor-infiltrating lymphocytes(TILs).Cytokines and chemokines analysis showed the combination therapy significantly increases the secretion of proinflammatory cytokines and chemokines in both responders and non-responders.Therefore,neoadjuvant ori and tori demonstrated promising antitumor activity with high response rates and high 2-year RFS/EFS for AM with acceptable tolerability.展开更多
To improve soil carbon sequestration capacity,the full soil carbon cycle process needs to be understood and quantified.It is essential to evaluate whether water erosion acts as a net source or sink of atmospheric CO_(...To improve soil carbon sequestration capacity,the full soil carbon cycle process needs to be understood and quantified.It is essential to evaluate whether water erosion acts as a net source or sink of atmospheric CO_(2)at the basin scale,which encompasses the entire hydrological process.This study introduced an approach that combined a spatially distributed sediment delivery model and biogeochemical model to estimate the lateral and vertical carbon fluxes by water erosion at the basin scale.Applying this coupling model to the Dongting Lake Basin,the results showed that the annual average amount of soil erosion during 1980-2020 was 1.33×10^(8)t,displaying a decreasing trend followed by a slight increase.Only 12% of the soil organic carbon displacement was ultimately lost in the riverine systems,and the rest was deposited downhill within the basin.The average lateral soil organic carbon loss induced by erosion was 8.86×10^(11)g C in 1980 and 1.50×10^(11)g C in 2020,with a decline rate of 83%.A net land sink for atmospheric CO_(2)of 5.54×1011g C a^(-1)occurred during erosion,primarily through sediment burial and dynamic replacement.However,ecological restoration projects and tillage practice policies are still significant in reducing erosion,which could improve the capacity of the carbon sink for recovery beyond the rate of horizontal carbon removal.Moreover,our model enables the spatial explicit simulation of erosion-induced carbon fluxes using costeffective and easily accessible input data across large spatial scales and long timeframes.Consequently,it offers a valuable tool for predicting the interactions between carbon dynamics,land use changes,and future climate.展开更多
Climate change alters the intensity and frequency of drought and rewetting(D/W)events;however,the influence patterns of D/W on soil N_(2)O efflux in the water-limited area were not fully understood.Therefore,the impac...Climate change alters the intensity and frequency of drought and rewetting(D/W)events;however,the influence patterns of D/W on soil N_(2)O efflux in the water-limited area were not fully understood.Therefore,the impacts of D/W cycles varying in different extent of rewetting and frequency to N_(2)O efflux in two kinds of soil on the Loess Plateau were investigated.The incubation conditions consisted of 1)D/W treatments with four 7-day cycles from 10%water holding capacity(WHC)to 60%WHC or 90%WHC,2)constant moisture of 60%WHC and 90%WHC.The pulse of N_(2)O efflux rate under 10-60%WHC treatment was higher than that under 10-90%WHC treatment in calcic cambisols,while opposite trend was observed in earth-cumuli-orthic anthrosols.Meanwhile,the pulse of N_(2)O efflux rate decreased as cycle number increased for different wetting intensities and soil types.The direct N_(2)O efflux under 10-60%WHC and 10-90%WHC treatments were 5.49 and 1.89μg N_(2)O-N g^(-1)soil in calcic cambisols,with those being 1.92 and 10.85μg N_(2)O-N g^(-1)soil in earth-cumuli-orthic anthrosols,respectively.The N loss in earth-cumuli-orthic anthrosols was approximately 5.74 times greater than that in calcic cambisols under 10-90%WHC treatment,whereas the N loss under 10-60%WHC treatment was about 2.86 times greater in calcic cambisols than that in earth-cumuli-orthic anthrosols.This study suggested that extreme rainfall events can enhance the N_(2)O efflux and N loss in agricultural soils on the Loess Plateau in terms of soil type and wetting intensity,which should not be ignored in the N fertilizer management.展开更多
For thousands of years,terracing has been one of the most important systems for preventing soil erosion,conserving water,and increasing agricultural production.Despite having a long history,the wide-ranging effects an...For thousands of years,terracing has been one of the most important systems for preventing soil erosion,conserving water,and increasing agricultural production.Despite having a long history,the wide-ranging effects and mechanisms of terracing are poorly understood owing to large-scale spatial and temporal distribution patterns and the challenges related to assessing the ecosystem services of terraced landscapes.Thus,our study aims to review comprehensively the effect of terraces by describing the mechanisms behind terraced systems.Terraces provide many ecosystem services,including the reduction of runoff and sediment by over 41.9%and 52%,respectively,and the improvement of grain yields and soil moisture content by 44.8%and 12.9%,respectively.In addition,terracing can also contribute toward the conservation of plant biodiversity on a local scale.However,as terraces age,a number of disadvantages gradually emerge,including interference with water circulation and the development of serious environmental problems caused by poorly designed or mismanaged terraces,where the average runoff and soil loss can be 1—5 times that of well-managed terraces.Although understanding the complexity and multifaceted effects of terracing is vital for terrace construction and management,the negative effects of terracing are often not considered,and existing studies have several shortcomings.Within this context,this paper aims to describe both the benefits and disadvantages of terracing,investigate the gaps in current research,as well as discuss preventive and remedial measures so as to negate the possible bad impacts of terracing.展开更多
Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation...Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation by fixing carbon in vegetation and soil.The Grain for Green Program(GFGP)of China is the largest ecological restoration program in the world closely related to land-use/land-cover change(LUCC).Systematically assessing the carbon sequestration benefit of GFGP is crucial for a better understanding of the effects of implementing GFGP and providing reasonable vegetation management.Therefore,we selected the hilly red soil region(HRSR)of southern China as a study area,which is one of the main ecologically vulnerable areas in China.We assessed the carbon sequestration in the GFGP area of the HRSR using the InVEST(Integrated Valuation of Environmental Services and Tradeoffs)model based on land-use/land-cover datasets during 2000e2015.Our results show that implementing GFGP is conducive to the enhancement of carbon sequestration services.Total carbon sequestration showed an increasing trend at a rate of 15.43%from 2000 to 2015.The most significant change mainly happened in Hunan Province with the shortest implementation time.The carbon sequestration of each carbon pool(namely aboveground biomass,belowground biomass,soil,and dead organic matter)also increased slightly.Additionally,for carbon sequestration,unused land converted to forest land is the most effective LUCC.This study can provide scientific support for the management and implementation of GFGP in the HRSR of China.展开更多
●Soil erosion resulted in homogenization of bacterial communities in the watershed.●Microbial community heterogeneity among erosion sites made soil tracing possible.●Assembly process results showed that the trackin...●Soil erosion resulted in homogenization of bacterial communities in the watershed.●Microbial community heterogeneity among erosion sites made soil tracing possible.●Assembly process results showed that the tracking results can achieve high precision.●Dryland was the main source of sediment deposition based on the result of FEAST.Sediment source tracing can accurately provide a theoretical basis for controlling soil erosion effectively,by identifying the most serious types of land use.Traditional sediment tracing methods are based on physical,chemical,biological,and composite fingerprinting,which have not included microbes.As high-throughput sequencing becomes more prevalent,microorganisms can provide more information than what we think.Thus,whether the microorganism can also be used as a special fingerprint factor for sediment source identification during soil erosion,we have tested it by using microbial source tracking tool FEAST to quantify the microbe contribution from five types of eroded land(including dryland,urban,paddy field,forest and grassland)to the depositional areas(Niubitan)in the Yuanjiang basin.The source microbial community in the erosive area was heterogeneous,and assembly process analysis further demonstrated that the source tracking results could reach higher accuracy.The results of FEAST showed that dryland(35.50%),urban(17.21%),paddy field(8.14%),and forest(1.07%)were the major contributors to Niubitan.Our results follow the general soil erosion rules and prove its validity.Taken together,a new perspective is provided by these results for tracing sediment sources in erosion-sedimentary systems.展开更多
With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and ...With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and cycle numbers alter microbial community and respiration is barely understood. Here,indoor DRW one and four cycles treatments were implemented on soil samples obtained from the Loess Plateau, involving increase of soil moisture from10% water-holding capacity(WHC) to 60% and 90% WHC(i.e., 10%–60% and 10%–90% WHC, respectively). Constant soil moistures of 10%, 60%,and 90% WHC were used as the controls. The results showed that bacterial diversity and richness decreased and those of fungi remained unchanged under DRW treatments compared to the controls. Under all moisture levels, Actinobacteriota and Ascomycota were the most dominant bacterial and fungal phyla,respectively. The bacterial network was more complex than that of fungi, indicating that bacteria had a greater potential for interaction and niche sharing under DRW treatments. The pulse of respiration rate declined as the DRW cycle increased under 10%–60% WHC, but remained similar for different cycles under 10%–90% WHC. Moreover, the DRW treatments reduced the overall carbon loss, and the direct carbon release under 10%–60% WHC was larger than that under 10%–90% WHC. The cumulative CO_(2) emissions after four DRW cycles were significantly positively correlated with microbial biomass carbon and negatively correlated with fungal richness(Chao 1).展开更多
Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different inten...Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different intensities on the microbial properties and respiration are not well understood.Thus,the responsive patterns of microbial communities and carbon mineralization in agriculture soil on the Chinese Loess Plateau to DRW treatments with different wetting intensities(5%-25% and 5%-36%)and frequency(1-cycle to 4-cycle)were investigated.Continuous moisture levels of 5%,25% and 36% were used as control.Results revealed that the reduction of bacterial diversity and richness were greater for 5%-36% than 5%-25% treatment,while diversity of fungi was similar for different wetting intensities.Bacterial communities became clustered by wetting intensity rather than cycle number,however fungal community was unaffected by DRW.The complexity of bacterial co-occurrence network increased because of higher nodes,edges,average degree,diameter and average cluster coefficient after 4-cycles,and the interaction was more complex after 1-cycle for fungi.Rewetting caused a pulse-like increase of respiration rate,and the pulse amplitude was greater for DRW with high rewetting intensity and decreased with the increase of cycle number.The cumulative CO_(2) emission for DRW treatments was lower than that for the continuous moisture conditions.The net reduction of carbon release for 5%-36% treatment was 1.18 times higher than that for 5%-25% treatment.Our study provides experimental evidence of the positive potential of DRW processes for maintaining soil carbon stock in an agriculture system on the Loess Plateau.展开更多
基金supported in part by the grants from Beijing Municipal Science&Technology Commission(No D171100006517002)
文摘Objective： To compare the effect of neoadjuvant chemotherapy （NACT） with adjuvant chemotherapy （ACT） using oxaliplatin plus S-1 （sex） or capecitabine （CapeOX） on gastric cancer patients with D2 lymphadenectomy. Methods： This was a two-by-two factorial randomized phase Ⅱ-Ⅲ trial, and registered on ISRCTN registry （No. ISRCTN12206108）. Locally advanced gastric cancer patients were randomized to neoadjuvant sex, neoadjuvant CapeOX, adjuvant sex, or adjuvant CapeOX arms. Primary analysis was performed on an intention- to-treat （ITT） basis using overall survival （OS） as primary endpoint. Results： This trial started in September 2011 and closed in December 2012 with 100 patients enrolled. Treatment completion rate was 56%, 52%, 38% and 30% in the four arms, respectively. NACT group had fewer dropouts due to unacceptable toxicity （P=0.042）. Surgical complication rate did not differ by the four groups （P=0.986）. No survival signifcant difference was found comparing NACT with ACT （P=0.664; 5-year-OS： 70% vs. 74% respectively）, nor between the sex and CapeOX groups （P=0.252; 5-year-OS： 78% vs. 66% respectively）. Subgroup analysis showed sex significantly improved survival in patents with diffuse type （P=0.048）. Conclusions： No significant survival difference was found between NACT and ACT. sex and CapeOX had good safety and efficacy as neoadjuvant regimens. Diffuse type patients may survive longer due to sex.
基金funding by the National Natural Science Foundation of China (No. 61520106004 and No. 81471640)
文摘Objective： To determine the capability of dynamic enhanced computed tomography（CT） to differentiate liver metastases（LMs） of well-differentiated from poorly-differentiated gastroenteropancreatic neuroendocrine neoplasms（GEP-NENs）.Methods： Patients with LMs of GEP-NENs who underwent dynamic enhanced CT examination in Peking University Cancer Hospital from January 2009 to October 2015 were included and data were retrospectively analyzed. We assessed the qualitative and quantitative CT features to identify the significant differentiating CT features of LMs of poorly-differentiated GEP-NENs from those of well-differentiated GEP-NENs using univariate analysis and a multivariate logistic regression model.Results： The study included 22 patients with LMs of well-differentiated GEP-NENs and 32 patients with LMs of poorly-differentiated GEP-NENs. Univariate analysis revealed statistically significant differences between the LMs of well-and poorly-differentiated GEP-NENs in terms of feeding arteries（36.4% vs. 75.0%, χ2=8.061,P=0.005）, intratumoral neovascularity（18.2% vs. 59.4%, χ2=9.047, P=0.003）, lymphadenopathy（27.3% vs. 81.2%,χ2=15.733, P〈0.001）, tumor-to-aortic ratio in the hepatic arterial and portal venous phase（T-A/AP： 0.297±0.080 vs.0.251±0.059, t=2.437, P=0.018; T-A/PVP： 0.639±0.138 vs. 0.529±0.117, t=3.163, P=0.003） and tumor-to-liver ratio in the hepatic arterial phase（T-L/AP： 1.108±0.267 vs. 0.907±0.240, t=2.882, P=0.006）. The LMs of poorlydifferentiated GEP-NENs showed more feeding arteries, more intratumoral neovascularity, more lymphadenopathy and a lower tumor-to-aortic ratio. Multivariate analysis suggested that intratumoral neovascularity [P=0.015, OR=0.108, 95% confidence interval（95% CI）, 0.018–0.646], lymphadenopathy（P=0.001,OR=0.055, 95% CI, 0.009–0.323） and T-A/PVP（P=0.004, OR=5.3 E–5, 95% CI, 0.000–0.044） were independent factors for differentiating LMs of poorly-differentiated from well-differentiated GEP-NENs.Conclusions： Dynamic enhanced CT features（intratumoral neovascularity, lymphadenopathy and T-A/PVP）are useful in the pathological classification of LMs of GEP-NENs.
文摘胃肝样腺癌(hepatoid adenocarcinoma of stomach,HAS)是一种特殊类型的胃癌。其发病率不高,但由于HAS具有高度侵袭性的生物学行为,容易发生淋巴转移及肝转移,预后较差,受到临床广泛关注。随着HAS临床病理特征、预后以及分子生物学特征等的持续研究,关于HAS的认识正不断深入。然而,目前在HAS研究领域仍存在一些容易被忽视并亟需解决的问题。本文梳理既往关于HAS的病例报道及研究,在HAS的范畴、起源、诊断方法、分子生物学特征及预后等方面进行总结和探讨,以期为HAS的后续研究提供一定方向。
基金supported by the National Science Foundation for Young Scientists of China (No. 81802735)
文摘Objective:To explore the intraperitoneal free cancer cell(IFCC)detection value of negative enrichment and immune fluorescence in situ hybridization(NEimFISH)on chromosomes(CEN)8/17.Methods:To verify the reliability of NEimFISH,29 gastric cancer tumors,their adjacent tissues and greater omental tissues were tested.Our study then included 105 gastric cancer patients for IFCC.We defined patients as IFCC-positive if a signal was detected,regardless of the detailed cancer cell numbers.A comparison of clinicopathological features was conducted among IFCC groups.We also compared the diagnosis value and peritoneal recurrence predictive value among different detection methods.The comparison of IFCC number was also conducted among different groups.Results:A cutoff of 2.5 positive cells could distinguish all benign tissue samples and 97%of malignant tissue samples in our study.Compared to intestinal gastric cancer,patients with diffuse gastric cancer tended to have more IFCCs(6 vs.4,P=0.002).The IFCC counts were often higher in the lymphovascular invasion positive group than negative group(3 vs.1,P=0.022).All IFCC samples that were considered positive using conventional cytology were also found to be positive using NEimFISH.When compared to conventional cytology and paraffin pathology,NEimFISH had a higher IFCC positive rate(68.9%)and higher one-year peritoneal recurrence predictive value with area under the curve(AUC)of 0.922.Conclusions:Gastric cancer could be effectively diagnosed by NEimFISH.The IFCC number found using NEimFISH on CEN8/17 is closely associated with Lauren type and vascular invasion of cancer.NEimFISH is a reliable detection modality with a higher positive detection rate,higher one-year peritoneal recurrence predictive value and quantitative features for IFCC of gastric cancer.
基金supported by grants from the National Natural Science Foundation of China(No.82173156)Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support(No.ZYLX202116)。
文摘Objective:The accurate prediction of tumor response to neoadjuvant chemoradiotherapy(nCRT)remains challenging.Few studies have investigated pathologic complete response(ypCR)prediction in patients with residual flat mucosal lesions after treatment.This study aimed to identify variables for predicting ypCR in patients with residual flat mucosal lesions after nCRT for locally advanced rectal cancer(LARC).Methods:Data of patients with residual flat mucosal lesions after nCRT who underwent radical resection between 2009 and 2015 were retrospectively collected from the LARC database at Peking University Cancer Hospital.Univariate and multivariate analyses of the association between clinicopathological factors and ypCR were performed,and a nomogram was constructed by incorporating the significant predictors.Results:Of the 246 patients with residual flat mucosal lesions included in the final analysis,56(22.8%)had ypCR.Univariate and multivariate analyses showed that pretreatment cT stage(pre-cT)≤T2(P=0.016),magnetic resonance tumor regression grade(MR-TRG)1-3(P=0.001)and residual mucosal lesion depth=0 mm(P<0.001)were associated with a higher rate of ypCR.A nomogram was developed with a concordance index(C-index)of0.759 and the calibration curve showed that the nomogram model had good predictive consistency.The follow-up time ranged from 3.0 to 113.3 months,with a median follow-up time of 63.77 months.The multivariate Cox regression model showed that the four variables in the nomogram model were not risk factors for disease-free survival(DFS)or overall survival(OS).Conclusions:Completely flat mucosa,early cT stage and good MR-TRG were predictive factors for ypCR instead of DFS or OS in patients with LARC with residual flat mucosal lesions after nCRT.Endoscopic mucosal re-evaluation before surgery is important,as it may contribute to decision-making and facilitate nonoperative management or organ preservation.
基金supported by a grant from Beijing Municipal Natural Science Foundation (No. 7172043)
文摘Objective: The present study investigated the prognosis value of preoperative fluorodeoxyglucose(FDG)positron emission tomography/computed tomography(PET/CT) in patients with local advanced gastric cancer(LAGC).Methods: In total, 144 patients [median age 63(range: 48-80) years old] with LAGC underwent 18 F-FDG PET/CT prior to any treatment. The maximum standardized uptake values(SUVmax), mean standardized uptake values(SUVmean), metabolic tumor volume(MTV) and total lesion glycolysis(TLG) of the primary lesion were measured on PET/CT and correlated with clinicopathological features and survival.Results: Significant differences in SUVmean, SUVmax, MTV and TLG were found according to Lauren’s classification, histologic grade and T category(P<0.05). During the 26.5-month follow-up, 51(35.4%) patients died and 70(48.6%) exhibited disease progression. The optimal thresholds of MTV and TLG were 15.1 cm^3 and 47.3 cm^3, respectively. The 3-year progression-free survival(PFS) and overall survival(OS) for patients with high TLG values were 30% and 38% compared to 38% and 47% for low TLG values, respectively(P<0.05). Univariate and multifactor analyses demonstrated that lymph node metastasis and T stage were independent prognostic factors for PFS;T stage, histologic grade and TLG were independent prognostic factors for OS(P<0.05). Molecular markers had no relationship with patient’s outcomes.Conclusions: Metabolic activity of primary gastric tumors from 18 F-FDG PET/CT is a prognostic factor in patients with LAGC.
基金This study was supported by Beijing Municipal Hospital Scientific Research Cultivation Program(No.PX2016057).We thank Xiaoping Kang for her help in data analysis.
文摘Objective:Fluoroscopy guidance is generally required for endobronchial ultrasonography with guide sheath(EBUS-GS)in peripheral pulmonary lesions(PPLs).Virtual bronchoscopic navigation(VBN)can guide the bronchoscope by creating virtual images of the bronchial route to the lesion.The diagnostic yield and safety profiles of VBN without fluoroscopy for PPLs have not been evaluated in inexperienced pulmonologist performing EBUS-GS.Methods:Between January 2016 and June 2017,consecutive patients with PPLs referred for EBUS-GS at a single cancer center were enrolled.The diagnostic yield as well as safety profiles was retrospectively analyzed,and our preliminary experience was shared.Results:A total of 109 patients with 109 lesions were included,99(90.8%)lesions were visible on EBUS imaging.According to the procedure time needed to locate the lesion on EBUS,24.8%(27/109)were deemed technically difficult procedures;however,no significant relationships were identified between candidate parameters and technically difficult procedures.The overall diagnosis yield was 74.3%(81/109),and the diagnostic yield of malignancy was 83.7%(77/92).Lesions larger than 20 mm[odds ratio(OR),2.758;95%confidence interval(95%CI),1.077-7.062;P=0.034]and probe of within type(OR,3.174;95%CI,1.151-8.757,P=0.026)were independent factors leading to a better diagnostic yield in multivariate analysis.About 30 practice procedures were needed to achieve a stable diagnostic yield,and the proportion of technically difficult procedures decreased and stabilized after 70 practice procedures.Regarding complications,one patient(0.9%)had intraoperative hemorrhage(100 mL)which was managed under endoscopy.Conclusions:VBN without fluoroscopy guidance is still useful and safe for PPLs diagnosis,especially for malignant diseases when performed by pulmonologist without previous experience of EBUS-GS.VBN may simplify the process of lesion positioning and further multi-center randomized studies are warranted.
基金Digestive Medical Coordinated Development Center of Beijing Municipal Administration of Hospitals(No.XXT20)。
文摘Objective:To explore the correlation between computed tomography(CT)features and combined positive score(CPS)of programmed cell death ligand 1(PD-L1)expression in patients with gastric cancer(GC).Methods:This study reviewed an institutional database of patients who underwent GC operation without neoadjuvant chemotherapy between December 2019 and September 2020.The CPS results of PD-L1 expression of postoperative histological examination were recorded by pathology.Baseline CT features were measured,and their correlation with CPS 5 or 10 score groups of PD-L1 expression was analyzed.Results:Data for 153 patients with GC were collected.Among them,124 were advanced GC patients,and 29were early GC patients.None of the CT features significantly differed between CPS groups with a cutoff score of 5and a score of 10 in patients with early GC.In advanced GC,the presence of lymph nodes with short diameters>10mm was significantly different(P=0.024)between the CPS<5 and CPS≥5 groups.CT features such as tumor attenuation in the arterial phase,long and short diameter of the largest lymph node,the sum of long diameter of the two largest lymph nodes,the sum of short diameter of the two largest lymph nodes,and the presence of lymph nodes with short diameters>10 mm significantly differed between the CPS<10 and CPS≥10 groups in advanced GC.The sensitivity,specificity and area under receiver operating characteristic(ROC)curve of logistic regression model for predicting CPS≥10 was 71.7%,50.0%and 0.671,respectively.Microsatellite instability(MSI)status was significantly different in CPS groups with cutoff score of 5 and 10 in advanced GC patients.Conclusions:CT findings of advanced GC patients with CPS≥10 showed greater arterial phase enhancement and larger lymph nodes.CT has the potential to help screen patients suitable for immunotherapy.
基金supported by Beijing Medical Award Foundation(No.YXJL-2020-0889-0106)Beijing Municipal Administration of Hospitals’Ascent Plan(No.DFL20220901)Beijing Xisike Clinical Oncology Research Foundation(Nos.Y-Roche2019/2-0076 and Y-SY201901-0270).
文摘Dear Editor,Extramammary Paget disease(EMPD)is a rare adenocarcinoma that originates in the apocrine gland-rich skin and usually affects the perineal skin(primary EMPD)or represents the intraepithelial spread of an underlying visceral carcinoma(secondary EMPD).Approximately half of EMPD cases are confined to the epidermis,which was defined as intraepithelial EMPD.
基金supported by the Natural Science Foundation of China(grant number 82002456)China Postdoctoral Science Foundation(grant number 2022M723207)+10 种基金the Medical Scientific Research Foundation of Zhejiang Province,China(grant number 2023KY666)Zhejiang Traditional Chinese Medicine Science Fund Project(grant number 2024ZL372)Qiantang Cross Fund Project(grant number 2023-16)National Natural Science Foundation of China of Zhejiang Cancer Hospital Cultivation Project(grant number PY2023006)the Medical Scientific Research Foundation of Zhejiang Province,China(grant number 2024KY812)the Natural Science Foundation of Zhejiang Province(grant number LQ24H160036)Beijing Health Technologies Promotion Program[grant number BHTPP2022041]Peking University Clinical Scientist Training Program and the Fundamental Research Funds for the Central Universities[grant number BMU2024PYJH010]Science Foundation of Peking University Cancer Hospital[grant number PY202333]the Beijing Natural Science Foundation[grant number 7232248]Beijing Hospitals Authority Youth Programme[grant number QML20231902].
文摘The BRAF gene is an important signaling molecule in human cells that is involved in the regulation of cell growth,differentiation,and survival.When the BRAF gene mutates,it can lead to abnormal activation of the signaling pathway,which promotes cell proliferation,inhibits cell apoptosis,and ultimately contributes to the occurrence and development of cancer.BRAF mutations are widely present in various cancers,including malignant melanoma,thyroid cancer,colorectal cancer,non-small cell lung cancer,and hairy cell leukemia,among others.BRAF is an important target for the treatment of various solid tumors,and targeted combination therapies,represented by BRAF inhibitors,have become one of the main treatment modalities for a variety of BRAF-mutation-positive solid tumors.
基金supported by the National Key Research and Development Program(2023YFC2506404)National Natural Science Foundation of China(82372869,82272676,and 82073011)+1 种基金Beijing Municipal Administration of Hospitals’Ascent Plan(DFL20220901,QML20231107)Beijing Natural Science Foundation(7242021).
文摘Neoadjuvant PD-1 inhibitor is promising in cutaneous melanoma but remains unknown in acral melanoma(AM).This phase Ib trial study(Clinicaltrials.gov NCT04197882)assessed the efficacy and safety of the combination of neoadjuvant oncolytic virus orienX010(ori)and anti-PD-1 toripalimab(tori)for resectable AM.Thirty patients of stage III/IV received neoadjuvant therapy of ori and tori for 12 weeks before surgery,followed by adjuvant treatment with tori for 1 year.Primary endpoints were radiographic and pathological response rates,with secondary endpoints of 1-and 2-year recurrence-free survival(RFS)rates,event-free survival(EFS)rates,and safety.Twenty-seven completed surgery and tori adjuvant treatment and median follow-up was 35.7 months.Radiographic and pathological response rates were 36.7%and 77.8%,with complete response rates of 3.3%and 14.8%,1-and 2-year RFS rates of 85.2%and 81.5%,and 1-and 2-year EFS rates of 83%and 73%,respectively.Adverse events occurred in all patients,mainly grade 1-2.There was no correlation between PET/CT evaluation and pathological response or progression-free survival/overall survival.Patients with pathological response showed tumor beds with high tertiary lymphoid structures(TLSs)and tumor-infiltrating lymphocytes(TILs).Cytokines and chemokines analysis showed the combination therapy significantly increases the secretion of proinflammatory cytokines and chemokines in both responders and non-responders.Therefore,neoadjuvant ori and tori demonstrated promising antitumor activity with high response rates and high 2-year RFS/EFS for AM with acceptable tolerability.
基金supported by the National Natural Science Foundation of China(Grant No.U19A2047)the Natural Science Foundation of Hunan Province(Grant No.2023JJ20030)。
文摘To improve soil carbon sequestration capacity,the full soil carbon cycle process needs to be understood and quantified.It is essential to evaluate whether water erosion acts as a net source or sink of atmospheric CO_(2)at the basin scale,which encompasses the entire hydrological process.This study introduced an approach that combined a spatially distributed sediment delivery model and biogeochemical model to estimate the lateral and vertical carbon fluxes by water erosion at the basin scale.Applying this coupling model to the Dongting Lake Basin,the results showed that the annual average amount of soil erosion during 1980-2020 was 1.33×10^(8)t,displaying a decreasing trend followed by a slight increase.Only 12% of the soil organic carbon displacement was ultimately lost in the riverine systems,and the rest was deposited downhill within the basin.The average lateral soil organic carbon loss induced by erosion was 8.86×10^(11)g C in 1980 and 1.50×10^(11)g C in 2020,with a decline rate of 83%.A net land sink for atmospheric CO_(2)of 5.54×1011g C a^(-1)occurred during erosion,primarily through sediment burial and dynamic replacement.However,ecological restoration projects and tillage practice policies are still significant in reducing erosion,which could improve the capacity of the carbon sink for recovery beyond the rate of horizontal carbon removal.Moreover,our model enables the spatial explicit simulation of erosion-induced carbon fluxes using costeffective and easily accessible input data across large spatial scales and long timeframes.Consequently,it offers a valuable tool for predicting the interactions between carbon dynamics,land use changes,and future climate.
基金This work was financially supported by the‘Hundred-talent Project’of the Chinese Academy of Sciences(A315021407).
文摘Climate change alters the intensity and frequency of drought and rewetting(D/W)events;however,the influence patterns of D/W on soil N_(2)O efflux in the water-limited area were not fully understood.Therefore,the impacts of D/W cycles varying in different extent of rewetting and frequency to N_(2)O efflux in two kinds of soil on the Loess Plateau were investigated.The incubation conditions consisted of 1)D/W treatments with four 7-day cycles from 10%water holding capacity(WHC)to 60%WHC or 90%WHC,2)constant moisture of 60%WHC and 90%WHC.The pulse of N_(2)O efflux rate under 10-60%WHC treatment was higher than that under 10-90%WHC treatment in calcic cambisols,while opposite trend was observed in earth-cumuli-orthic anthrosols.Meanwhile,the pulse of N_(2)O efflux rate decreased as cycle number increased for different wetting intensities and soil types.The direct N_(2)O efflux under 10-60%WHC and 10-90%WHC treatments were 5.49 and 1.89μg N_(2)O-N g^(-1)soil in calcic cambisols,with those being 1.92 and 10.85μg N_(2)O-N g^(-1)soil in earth-cumuli-orthic anthrosols,respectively.The N loss in earth-cumuli-orthic anthrosols was approximately 5.74 times greater than that in calcic cambisols under 10-90%WHC treatment,whereas the N loss under 10-60%WHC treatment was about 2.86 times greater in calcic cambisols than that in earth-cumuli-orthic anthrosols.This study suggested that extreme rainfall events can enhance the N_(2)O efflux and N loss in agricultural soils on the Loess Plateau in terms of soil type and wetting intensity,which should not be ignored in the N fertilizer management.
基金Financial support for this research was provided by the National Natural Science Foundation of China(No.U19A2047,41877084)the Key Project of Department of Education of Hunan Province(No.18A044)the Water Resources Science and Technology Project of Hunan Province(Xiang shui ke ji[2017]230-40).
文摘For thousands of years,terracing has been one of the most important systems for preventing soil erosion,conserving water,and increasing agricultural production.Despite having a long history,the wide-ranging effects and mechanisms of terracing are poorly understood owing to large-scale spatial and temporal distribution patterns and the challenges related to assessing the ecosystem services of terraced landscapes.Thus,our study aims to review comprehensively the effect of terraces by describing the mechanisms behind terraced systems.Terraces provide many ecosystem services,including the reduction of runoff and sediment by over 41.9%and 52%,respectively,and the improvement of grain yields and soil moisture content by 44.8%and 12.9%,respectively.In addition,terracing can also contribute toward the conservation of plant biodiversity on a local scale.However,as terraces age,a number of disadvantages gradually emerge,including interference with water circulation and the development of serious environmental problems caused by poorly designed or mismanaged terraces,where the average runoff and soil loss can be 1—5 times that of well-managed terraces.Although understanding the complexity and multifaceted effects of terracing is vital for terrace construction and management,the negative effects of terracing are often not considered,and existing studies have several shortcomings.Within this context,this paper aims to describe both the benefits and disadvantages of terracing,investigate the gaps in current research,as well as discuss preventive and remedial measures so as to negate the possible bad impacts of terracing.
基金This research was funded by the National Key Research and Development Program of China(2017YFC0505401).
文摘Soil erosion disturbs not only the global carbon cycle,but it is a complex environmental problem.Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation by fixing carbon in vegetation and soil.The Grain for Green Program(GFGP)of China is the largest ecological restoration program in the world closely related to land-use/land-cover change(LUCC).Systematically assessing the carbon sequestration benefit of GFGP is crucial for a better understanding of the effects of implementing GFGP and providing reasonable vegetation management.Therefore,we selected the hilly red soil region(HRSR)of southern China as a study area,which is one of the main ecologically vulnerable areas in China.We assessed the carbon sequestration in the GFGP area of the HRSR using the InVEST(Integrated Valuation of Environmental Services and Tradeoffs)model based on land-use/land-cover datasets during 2000e2015.Our results show that implementing GFGP is conducive to the enhancement of carbon sequestration services.Total carbon sequestration showed an increasing trend at a rate of 15.43%from 2000 to 2015.The most significant change mainly happened in Hunan Province with the shortest implementation time.The carbon sequestration of each carbon pool(namely aboveground biomass,belowground biomass,soil,and dead organic matter)also increased slightly.Additionally,for carbon sequestration,unused land converted to forest land is the most effective LUCC.This study can provide scientific support for the management and implementation of GFGP in the HRSR of China.
基金The National Natural Science Foundation of China provided funding for this project(U19A2047).
文摘●Soil erosion resulted in homogenization of bacterial communities in the watershed.●Microbial community heterogeneity among erosion sites made soil tracing possible.●Assembly process results showed that the tracking results can achieve high precision.●Dryland was the main source of sediment deposition based on the result of FEAST.Sediment source tracing can accurately provide a theoretical basis for controlling soil erosion effectively,by identifying the most serious types of land use.Traditional sediment tracing methods are based on physical,chemical,biological,and composite fingerprinting,which have not included microbes.As high-throughput sequencing becomes more prevalent,microorganisms can provide more information than what we think.Thus,whether the microorganism can also be used as a special fingerprint factor for sediment source identification during soil erosion,we have tested it by using microbial source tracking tool FEAST to quantify the microbe contribution from five types of eroded land(including dryland,urban,paddy field,forest and grassland)to the depositional areas(Niubitan)in the Yuanjiang basin.The source microbial community in the erosive area was heterogeneous,and assembly process analysis further demonstrated that the source tracking results could reach higher accuracy.The results of FEAST showed that dryland(35.50%),urban(17.21%),paddy field(8.14%),and forest(1.07%)were the major contributors to Niubitan.Our results follow the general soil erosion rules and prove its validity.Taken together,a new perspective is provided by these results for tracing sediment sources in erosion-sedimentary systems.
基金supported by the Provincial Natural Science Foundation of Hunan, China (No. 2020JJ4429)the Open Fund of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau of China (No. A314021402-202101)the Hundred-Talent Project of Chinese Academy of Sciences (No. A315021407).
文摘With global climate change, soil drying-rewetting(DRW) events have intensified and occurred frequently on the Loess Plateau of China. However, the extent to which the DRW cycles with different wetting intensities and cycle numbers alter microbial community and respiration is barely understood. Here,indoor DRW one and four cycles treatments were implemented on soil samples obtained from the Loess Plateau, involving increase of soil moisture from10% water-holding capacity(WHC) to 60% and 90% WHC(i.e., 10%–60% and 10%–90% WHC, respectively). Constant soil moistures of 10%, 60%,and 90% WHC were used as the controls. The results showed that bacterial diversity and richness decreased and those of fungi remained unchanged under DRW treatments compared to the controls. Under all moisture levels, Actinobacteriota and Ascomycota were the most dominant bacterial and fungal phyla,respectively. The bacterial network was more complex than that of fungi, indicating that bacteria had a greater potential for interaction and niche sharing under DRW treatments. The pulse of respiration rate declined as the DRW cycle increased under 10%–60% WHC, but remained similar for different cycles under 10%–90% WHC. Moreover, the DRW treatments reduced the overall carbon loss, and the direct carbon release under 10%–60% WHC was larger than that under 10%–90% WHC. The cumulative CO_(2) emissions after four DRW cycles were significantly positively correlated with microbial biomass carbon and negatively correlated with fungal richness(Chao 1).
基金financially supported by the Hundred-talent Project of the Chinese Academy of Sciences(A315021407).
文摘Altered drying-rewetting(DRW)procedures due to climate change may influence soil microbial properties and microbially-mediated carbon cycling in arid and semi-arid regions.However,the effects of DRW of different intensities on the microbial properties and respiration are not well understood.Thus,the responsive patterns of microbial communities and carbon mineralization in agriculture soil on the Chinese Loess Plateau to DRW treatments with different wetting intensities(5%-25% and 5%-36%)and frequency(1-cycle to 4-cycle)were investigated.Continuous moisture levels of 5%,25% and 36% were used as control.Results revealed that the reduction of bacterial diversity and richness were greater for 5%-36% than 5%-25% treatment,while diversity of fungi was similar for different wetting intensities.Bacterial communities became clustered by wetting intensity rather than cycle number,however fungal community was unaffected by DRW.The complexity of bacterial co-occurrence network increased because of higher nodes,edges,average degree,diameter and average cluster coefficient after 4-cycles,and the interaction was more complex after 1-cycle for fungi.Rewetting caused a pulse-like increase of respiration rate,and the pulse amplitude was greater for DRW with high rewetting intensity and decreased with the increase of cycle number.The cumulative CO_(2) emission for DRW treatments was lower than that for the continuous moisture conditions.The net reduction of carbon release for 5%-36% treatment was 1.18 times higher than that for 5%-25% treatment.Our study provides experimental evidence of the positive potential of DRW processes for maintaining soil carbon stock in an agriculture system on the Loess Plateau.
