[Effects of long-term nitrogen addition on the nitrogen pools in a meadow steppe ecosystem]. / é•¿æœŸæ°®æ·»åŠ å¯¹è‰ç”¸è‰åŽŸç”Ÿæ€ç³»ç»Ÿæ°®åº“çš„å½±å“.

Increasing atmospheric nitrogen (N) deposition greatly affects species diversity, productivity, and stability of ecosystems. It is thus of the great importance to understand how grassland N pools respond to the increased atmospheric N deposition. This study was conducted in a meadow steppe in Erguna, Inner Mongolia, China. There were six levels of N addition (i.e., 0, 2, 5, 10, 20 and 50 g·m-2·a-1) and two levels of mowing (i.e., mowing and unmown). Samples of aboveground tissues of dominant plant, root, aboveground litter, and soil to the depth of 100 cm were collected in the seventh year after treatments. The N content was measured and the N pool was calculated. The results showed that N addition significantly increased the N content of aboveground plant tissues and litter, as well as N pools of Leymus chinensis, plant community, litter and ecosystem. Mowing significantly increased the N content of L. chinensis leaf and litter, but reduced N pools of L. chinensis, plant community and litter, and did not affect their responses to N addition. There was a significant interactive effect between mowing and N addition on plant community N pool. High levels of N addition in the unmown treatment led to more N stored in the litter pool, with the saturation threshold for the plant community N pool occurred at 10 g·m-2·a-1. Under mowing treatment, the plant community N pool increased with the increasing N addition, and more N stored in plant community N pool after mowing. Mowing could alleviate the negative impacts of increasing N deposition on biodiversity and ecosystem stability, and extended postponing the occurrence of ecosystem N saturation induced by increasing N deposition.

Mobility loss and its restoration in China grasslands.

Loss of mobility in rangeland use has emerged as a dominant theory to explain ecosystem degradation in the research area of rangeland ecology. The loss of mobility in rangeland use in China resulted from multiple interacting natural and social factors as well as policy changes. Re-establi-shing mobility in rangeland use is critical to rangeland restoration and sustainable management in China. However, the recovery of rangeland might be difficult through simply reverting to traditional rotational grazing. Alternatively, we explored various state-of-the-art rangeland management techniques, including smart fence, intelligent wearables for livestock, and rapid forage biomass measurement using drones. Such novel rangeland management techniques could be used in different regions with different climate and vegetation in China to re-establish mobility in rangeland utilization. Paired with these advanced techniques, new rotational high-mobility grazing systems could further integrate with other essential measures of grass-livestock husbandry in China, such as balancing of forage production and livestock grazing, supplemental forage of livestock, and replenishment of soil nutrients in rangeland. All these practices would ensure a more sustainable and effective utilization of rangeland in China.

Pemetrexed-based chemotherapy for non-small-cell lung cancer patients with EGFR exon 20 insertion mutation: a multicenter study.

BACKGROUND: Chemotherapy is the major choice for advanced non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor exon 20 insertion (EGFR ex20ins). The efficacy of pemetrexed-based with other chemotherapy regimens and EGFR ex20ins subtypes in this population has not been well studied. METHODS: We screened patients with EGFR ex20ins by next-generation sequencing (NGS) from a large cohort. The clinicopathologic and medical information were collected in advanced NSCLC patients with EGFR ex20ins. We also compared the clinical outcomes among patients with different subtypes of EGFR ex20ins. RESULTS: We retrospectively collected 119 stage IIIB/IV NSCLC patients with EGFR ex20ins from 9142 NSCLC patients across China from June 2013 to December 2018. The subtypes of EGFR ex20ins included A767_V769dupASV (33/119, 27.73%), S768_D770dupSVD (19/119, 15.97%), N771_H773dupNPH (11/119, 9.24%), A763_Y764insFQEA (2/119, 1.68%) and others (54/119, 45.38%). A total of 64.7% (77/119) of patients received pemetrexed-based first-line chemotherapy and 13.45% (16/119) of patients received pemetrexed-based second-line chemotherapy. Pemetrexed-based chemo-treated patients had longer median progression-free survival (PFS) than patients without pemetrexed-based chemo-treated (5.5 vs. 3.0 months, P=0.0026). Survival data was available for 66 patients and the median overall survival (OS) was 24.7 months. Pemetrexed-based chemo-treated patients had longer OS tendency than patients without pemetrexed-based chemo-treated (25.0 vs. 19.6 months, P=0.0769). Patients harboring A767_V769dupASV had better OS than other subtypes of EGFR ex20ins but without statistical significance (P=0.0676). Multivariate analysis revealed that histological type of NSCLC and bone-metastasis before treatment were independent prognostic factors for OS in all patients after adjusting all characteristic and treatment factors (P<0.05). CONCLUSIONS: To the best of our knowledge, it is the largest cohort study of advanced NSCLC patients with EGFR ex20ins across China. Pemetrexed-based treatment could have better control of disease than non-pemetrexed-based chemotherapies in this population. Furthermore, more effective agents are expected for patients harboring EGFR ex20ins.

[Responses of soil potential carbon/nitrogen mineralization and microbial activities to extreme droughts in a meadow steppe]. / 草甸草原土壤碳/氮矿化潜力及土壤微生物水分敏感性对极端干旱的响应.

The mineralization of soil carbon (C) and nitrogen (N) is a critical process in the cycling of C and N in terrestrial ecosystems, which is strongly controlled by water availability. In this study, we collected soil samples in a 3-year extreme drought experiment in a meadow steppe in Inner Mongolia, freeze-dried these samples, and measured the potential C and N mineralization rates and water sensitivity of soil microorganism by incubating soils under soil water contents (SWC) of 3%, 8%, 13%, 18%, 25% and 35%. The results showed that averaged across different SWC, the extreme drought treatment of reducing 66% precipitation in growing season significantly increased potential N mineralization rate by 14.2%, but did not affect the potential C mineralization. Extreme drought significantly increased soil microbial biomass N and soil dissolved organic C by 26.8% and 26.9%, respectively. In both the control (natural rainfall) and extreme drought treatment, the potential C and N mineralization and microbial biomass C and N increased with SWC in the incubation, which was possibly caused by the enhanced substrate diffusion. Extreme drought also promoted the initial pulse response of C mineralization, implying the enhanced microbial response to water availability. Extreme drought significantly reduced the ratio of the potential soil C mineralization to the potential N mineralization, suggesting that extreme drought might weak the coupling of soil C and N. Extreme drought could cause different responses to soil water availability between soil C and N cycling. Extreme drought could enhance microbial response to increasing water availability, weak coupling between soil C and N, with consequences on nutrient cycling and primary productivity in the meadow steppe of northern China.

PD-L1 expression level in different thymoma stages and thymic carcinoma: a meta-analysis.

BACKGROUND: The immune checkpoint ligand, programmed cell death 1 ligand 1 (PD-L1), is expressed in various tumors and associated with response to drugs that target programmed cell death protein 1. Previous studies have estimated the level of PD-L1 expression among different stages of thymoma and thymic carcinoma to evaluate its potential use as a diagnostic factor; however, its varying expression level has been problematic. We conducted this meta-analysis of published literature to evaluate PD-L1 expression in thymomas and thymic carcinomas. METHODS: We analyzed 12 studies that included 320 patients with type A/AB/B1 thymoma, 225 patients with type B2/B3 thymoma, and 180 patients with thymic carcinoma. RESULTS: No difference in PD-L1 expression level was found between the B2/B3 vs C groups (odds ratio [OR], 0.67; 95% confidence interval [CI], 0.26, 1.76; p = 0.42). However, the heterogeneity was very high (I2 = 78%), and a significant difference was found between groups A/AB/B1 and B2/B3 (OR, 0.22; 95% CI, 0.12, 0.41; p < 0.001), with a relatively low heterogeneity (I2 = 55%). CONCLUSION: PD-L1 positivity might be a useful factor to differentiate type A/AB/B1 thymoma from type B2/B3 and thymic carcinoma. This result might be valuable for potential anti PD-L1 treatment in thymoma and thymic carcinoma.

[Effects of nitrogen and plant growth promoter addition on the growth and competitiveness of Leymus chinensis]. / æ°®ç´ å’Œæ¤ç‰©ç”Ÿé•¿ä¿ƒè¿›å‰‚å¯¹ç¾Šè‰ç”Ÿé•¿åŠç«žäº‰åŠ›çš„å½±å“.

With a greenhouse pot experiment, we investigated the effects of nitrogen (N) and plant growth promoter (brassinolide, BR) addition on the growth and competitive ability of three common plant species of typical steppe in Inner Mongolia, including Leymus chinensis, Astragalus adsurgens and Stipa krylovii. We added N at rates of 0, 0.1, 0.2, 0.4, 0.8 mg·g-1 soil and BR at rates of 0 and 0.005 mg·g-1 soil during plant growth in monoculture or with L. chinensis being planted in mixing with other two species, respectively. There were significant effects on biomass of L. chinensis and A. adsurgens, but not on that of S. krylovii with increase of N and BR addition. The effects of N addition on the growth of L. chinensis varied with accompanying plant species. Nitrogen addition increased aboveground biomass production of L. chinensis when growing in monoculture and mixed with A. adsurgens, but decreased its belowground biomass when growing mixed with S. krylovii. With increasing soil N availability, plant biomass allocation of L. chinensis showed significant decrease in root-shoot ratio when it was in monoculture or mixed with S. krylovii, but similar changes were not found when it was planted in mixing with A. adsurgens. The significant effects of BR addition on plant growth appeared occasionally. BR addition significantly reduced belowground biomass of A. adsurgens in its monoculture and significantly increased aboveground biomass of L. chinensis when it was planted in mixing with A. adsurgens. The results indicated that the appropria-tely combined addition of N and BR could effectively enhance biomass production of specific species combinations in grasslands, which has application prospects in the restoration of degraded grassland.

Global Phosphoproteomic Analysis Reveals the Defense and Response Mechanisms of Jatropha Curcas Seedling under Chilling Stress.

As a promising energy plant for biodiesel, Jatropha curcas is a tropical and subtropical shrub and its growth is affected by one of major abiotic stress, chilling. Therefore, we adopt the phosphoproteomic analysis, physiological measurement and ultrastructure observation to illustrate the responsive mechanism of J. curcas seedling under chilling (4 °C) stress. After chilling for 6 h, 308 significantly changed phosphoproteins were detected. Prolonged the chilling treatment for 24 h, obvious physiological injury can be observed and a total of 332 phosphoproteins were examined to be significantly changed. After recovery (28 °C) for 24 h, 291 phosphoproteins were varied at the phosphorylation level. GO analysis showed that significantly changed phosphoproteins were mainly responsible for cellular protein modification process, transport, cellular component organization and signal transduction at the chilling and recovery periods. On the basis of protein-protein interaction network analysis, phosphorylation of several protein kinases, such as SnRK2, MEKK1, EDR1, CDPK, EIN2, EIN4, PI4K and 14-3-3 were possibly responsible for cross-talk between ABA, Ca2+, ethylene and phosphoinositide mediated signaling pathways. We also highlighted the phosphorylation of HOS1, APX and PIP2 might be associated with response to chilling stress in J. curcas seedling. These results will be valuable for further study from the molecular breeding perspective.

The role of CXC cytokines as biomarkers and potential targets in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the deadliest cancers worldwide. At present, few effective biomarkers and targets are available for prognosis and treatment of HCC. Chemokines are a group of small proinflammatory chemoattractant cytokines binding to specific G-protein-coupled seven-span transmembrane receptors, which could recruit various immune cells to diverse tissues. Mountainous evidence from cell lines, animal models, even human liver tissues indicates that CXC cytokines display a strong correlation with HCC tumorigenesis. Nevertheless, the accurate expression patterns as well as functions of these CXCLs remain unclear. This study aims to explore the mRNA transcriptional and survival analysis of CXCLs in patients with HCC from the databases involving ONCOMINE, GEPIA, and cBioPortal databases. The result showed that the mRNA expression levels of CXCL2/12/14 were significantly lower in HCC tissues than those in adjacent tissues. By contrast, the mRNA expression levels of CXCL9/10 were significantly higher in HCC tissues. The expression levels of CXCL3/5 were correlated with different tumor stages. The survival analysis demonstrated that high transcriptional levels of CLCL1/3/5/8 may exhibit poorer overall survival in patients with HCC while high CXCL2 in patients with HCC may confer better overall survival. In conclusion, our study uncovered that CXCL2/5/9/10/12/14 may be novel biomarkers for the prognosis of HCC and that CXCL1/2/3/5/8 could server as potential targets in the precise treatment of HCC.

A meta-analysis of association between serum iron levels and lung cancer risk.

Many studies conducted on the relationship between serum iron levels and lung cancer risk had produced inconsistent results. We therefore conducted a meta-analysis to determine whether serum iron levels were lower in lung cancer patients compared to those in controls.A literature survey was conducted by searching the PubMed, WanFang, CNKI, and SinoMed databases for articles published as of Mar 1, 2018. Standard mean differences (SMD) with the corresponding 95% confidence intervals (CI) were executed by Stata 12.0 software. A total of 13 publications involving 1118 lung cancer patients and 832 controls were included in our study. The combined results showed that serum iron levels in lung cancer cases had no significantly lower when compared to those in controls [summary SMD = -0.125, 95%CI= -0.439, 0.189, Z = 0.78, p for Z test= 0.435], with high heterogeneity (I2= 89.9%, P< 0.001) found. In the stratified analysis by geographic locations, consistent results were found for serum iron levels between lung cancer patients and controls both in Asian populations [summary SMD = -0.113, 95%CI= -0.471, 0.245] and European populations [summary SMD = -0.215, 95%CI= -0.835, 0.404]. Publication bias was not found when evaluated by Begg's funnel plot and Egger's regression asymmetry test.In summary, the current study showed that serum iron levels had no significant association on lung cancer risk.

[Construction of Graphitic Carbon Nitride-Bismuth Oxyiodide Layered Heterostructures and Their Photocatalytic Antibacterial Performance].

The thin layered graphitic carbon nitride (g-C3N4) was prepared by the thermal polymerization process with urea as the precursor. The layered heterostructure of graphitic carbon nitride-bismuth oxyiodide (g-C3N4/BiOI) was constructed by the in-situ synthetization of bismuth oxyiodide (BiOI) on the surface of the thin layered g-C3N4. The morphology, specific surface area, crystal structure, molecular structure, light absorption properties, and surface properties were characterized by TEM, BET, XRD, FT-IR, UV-Vis DRS, and XPS, respectively. The disinfection performance of the synthesized catalysts under visible light irradiation was investigated. The antibacterial mechanism of g-C3N4/BiOI in the photocatalytic process was further revealed by the capture of sacrificial agents. The results indicate that the prepared sample has a layered heterojunction structure with a specific surface area of 63 m2·g-1 and its light absorption side can obtain 600 nm. The results of the photocatalytic activity test indicate that g-C3N4/BiOI can kill bacteria within 4 h, which is significantly higher than that of g-C3N4 and BiOI. The main active species of g-C3N4/BiOI in the photocatalytic process can be attributed to the photogenerated holes.

OTX1 Contributes to Hepatocellular Carcinoma Progression by Regulation of ERK/MAPK Pathway.

Orthodenticlehomeobox 1 (OTX1) overexpression had previously been associated with the progression of several tumors. The present study aimed to determine the expression and role of OTX1 in human hepatocellular carcinoma (HCC). The expression level of OTX1 was examined by quantitative real-time PCR (qRT-PCR) in 10 samples of HCC and paired adjacent non-cancerous tissues, and by immunohistochemistry (IHC) analysis in 128 HCC samples and matched controls. The relationship between OTX1 expression and the clinicopathological features werealso analyzed. Furthermore, the effects of OTX1 knockdown on cell proliferation and migration were determined in HCC cell lines. Axenograft mouse model was also established to investigate the role of OTX1 in HCC tumor growth. TheqRT-PCR and IHC analyses revealed that OTX1 was significantly elevated in HCC tissues compared with the paired non-cancerous controls. Expression of OTX1 was positively correlated with nodal metastasis status (P = 0.009) and TNM staging (P = 0.001) in HCC tissues. In addition, knockdown of OTX1 by shRNA significantly inhibited the proliferation and migration, and induced cell cycle arrest in S phase in vitro. Tumor growth was markedly inhibited by OTX1 silencing in the xenograft. Moreover, OTX1 silencing was causable for the decreased phosphorylation level of ERK/MAPK signaling. In conclusion, OTX1 contributes to HCC progression possibly by regulation of ERK/MAPK pathway. OTX1 may be a novel target for molecular therapy towards HCC.

Methane emissions from the trunks of living trees on upland soils.

Upland forests are traditionally thought to be net sinks for atmospheric methane (CH4 ). In such forests, in situ CH4 fluxes on tree trunks have been neglected relative to soil and canopy fluxes. We measured in situ CH4 fluxes from the trunks of living trees and other surfaces, such as twigs and soils, using a static closed-chamber method, and estimated the CH4 budget in a temperate upland forest in Beijing. We found that the trunks of Populus davidiana emitted large quantities of CH4 during July 2014-July 2015, amounting to mean annual emissions of 85.3 and 103.1 µg m(-2)  h(-1) on a trunk surface area basis on two replicate plots. The emission rates were similar in magnitude to those from tree trunks in wetland forests. The emitted CH4 was derived from the heartwood of trunks. On a plot or ecosystem scale, trunk CH4 emissions were equivalent to c. 30-90% of the amount of CH4 consumed by soils throughout the year, with an annual average of 63%. Our findings suggest that wet heartwoods, regardless of rot or not, occur widely in living trees on various habitats, where CH4 can be produced.

[Effects of plant functional groups removal on the soil carbon, nitrogen pools in a Leymus chinensis community of typical steppe in Inner Mongolia].

A field plant functional groups (PFGs) removal experiment was conducted in 2005-2007 to study the effects of plant diversity in a Leymus chinensis community of typical steppe in Inner Mongolia on the topsoil (0-10 cm) carbon (C) and nitrogen (N) pools. In the three successive years, the topsoil total C and N contents had a slight change (< 15%). They changed little in 2005, but were significantly higher in 2006 than in 2007 (P < 0.05). The topsoil NH4(+)-N content had a greater inter-annual change, being 80% higher in 2006 than in 2007, while the NO3(-)-N content had less significant change (P > 0.05). There was a positive linear relationship (P < 0.05) between the number of removed PFGs and the content of soil NO3(-)-N, which meant that the decrease of plant diversity increased soil NO3(-)-N content, and consequently, led to a possible soil nitrogen loss through leaching.

[Determination of trace elements in electrical absorption prospecting polyform sample by inductively coupled plasma mass spectrometry].

An ICP-MS method was established for the determination of sixteen trace elements, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Nb, Mo, Ag, Cd, Au, Tl, Pb and Bi in electrical absorption prospecting polyform. Three methods for polyform samples (ashing method, extraction by HNO3 + H2O2 and digestion with aqua regia) were compared and the results showed that the second method is the best one. The best operational paramenters of X series ICP-MS were confirmed, the inner standard 103Rh and 185Re were selected for the determination of elements, and analysis of isotopes interference correction equations was established. Satisfactory linearity of working curves of the sixteen trace elements was obtained, giving all their correlation coefficients over 0.999 8. The determination limit of the analytes was in the range of 0.001-2.2 microg x g(-1). The precision was 1.39%-4.84%, and the recoveries were between 94.86% and 105.2%. The method is sensitive, quick and simple and has been applied to the analysis of a great number of polyform samples.

Aluminum-induced ethylene production is associated with inhibition of root elongation in Lotus japonicus L.

Inhibition of root elongation by toxic aluminum (Al(3+)) occurs rapidly and is one of the most distinct and earliest symptoms of Al toxicity. To elucidate mechanism underlying Al(3+)-induced inhibition of root elongation, we investigated the involvement of ethylene in Al(3+)-induced inhibition of root elongation using the legume model plants Lotus japonicus and Medicago truncatula. Root elongation of L. japonicus and M. truncatula was rapidly inhibited by exposure to AlCl(3). A similar rapid inhibition of root elongation by the ethylene-releasing substance, ethephon, and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), was also observed. The Al(3+)-induced inhibition of root elongation was substantially ameliorated in the presence of antagonists of ethylene biosynthesis [Co(2+) and aminoethoxyvinylglycine (AVG)]. Al(3+) increased the activity of ACC oxidase (ACO), and induced a rapid evolution of ethylene from root apices and expression of genes of ACC synthase (ACS) and ACO. These findings suggest that induction of ethylene evolution resulting from up-regulation of ACS and ACO plays a critical role in Al(3+)-induced inhibition of root elongation.

Adsorption/desorption behavior between a novel amphoteric granular lignin adsorbent and reactive red K-3B in aqueous solutions.

A novel amphoteric granular lignin adsorbent (AGLA) was prepared using magnesium lignosulfonate as a raw material which was provided by a straw sulfite pulp mill in Guangdong Province, China. A reactive dye (red K-3B) was used as an adsorbate to investigate the adsorption behavior by static and mobile ways. The removal of reactive red K-3B was found to be initially pH and concentration dependent. Moreover, an increase of solution temperature ranging from 5 degrees C to 60 degrees C helped to enhance the rate of intraparticle diffusion of adsorbate and changes in the size of the pores of the adsorbent and thus to reduce the adsorption time. The total breakthrough adsorption capacity was 531 mg/g, and the saturated adsorption capacity was 560 mg/g, which prevailed over the activated carbons evidently. The reactive red K-3B adsorbed on AGLA could be recovered with a mixture of alcohol, NaCl and HCl aqueous solutions. The recovery percentage could reach 92.4%.

[The research on the law of greenhouse gases emission from warm temperate forest soils in Beijing region].

In situ measurements by closed chamber technique were done to investigate the law of greenhouse gases (Methane, carbon dioxide and Nitrous Oxide) fluxes emission from different warm temperate forest soils (Broad-leaved forest, Form. Quercus liaotungensis and Form. Pinus tabulae) of Dongling mountain in Beijing region. Results show that the all representative types forest soils were sink of CH4 and source of CO2 and N2O. Different type of vegetables and soils result of different fluxes range of the main greenhouse gases. The fluxes range of CH4, CO2 and N2O emission from the three types forest soils were: 42-103 micrograms/(m2.h), 15-344 mg/(m2.h) and -61-101 micrograms/(m2.h); 13-182 micrograms CH4/m2.h, 23-380 mg/(m2.h) and -15-183 micrograms/(m2.h); 12-128 ug CH4/m2.h, 15-292 mg/(m2.h) and -94-153 micrograms/(m2.h); respectively. The mean fluxes of CH4, CO2 and N2O emission from the three types forest soils during the observation period were: -66 micrograms/(m2.h), 145 mg/(m2.h) and 22 micrograms/(m2.h); -67 micrograms/(m2.h), 146 mg/(m2.h) and 45 micrograms/(m2.h); -79 micrograms/(m2.h), 150 mg/(m2.h) and 31 micrograms/(m2.h), respectively. The total amounts of CH4 CO2 and N2O emission from the three types forest soils were -5.34 kg/(hm2.a), 13.9 Mg/(hm2.a) and 2.58 kg/(hm2.a); -6.20 kg/(hm2.a), 14.07 Mg/(hm2.a) and 4.19 kg/(hm2.a); -6.85 kg/(hm2.a), 15.71 Mg/(hm2.a) and 4.30 kg/(hm2.a), respectively.

Long-term impacts of land-use change on dynamics of tropical soil carbon and nitrogen pools.

Land-use changes, especially the conversion of native forest vegetation to cropland and plantations in tropical region, can alter soil C and N pools and N availability for plant uptake. Deforestation, followed by shifting cultivation and establishment of rubber tree plantation, is a common land-use change in Xishuangbanna, southwest China. However the influence of this kind of land-use change on soil C and N dynamics in this region remains poorly understood. This study was conducted to assess the effects of land-use change on soil C and N pools. Soil samples were collected on five adjacent plots, which belong to three land-use types including secondary forest-an acuminate banana (Musa itinerans) secondary forest and a male bamboo (Dendrocalamus membranaceae) secondary forest, shifting cultivation, and rubber tree (Hevea brasiliensis (H. B. K.) Muell. Arg.) plantation (one plot is 3-year-old, and another is 7-year-old). We measured soil bulk density (BD), pH value, moisture content and concentrations of soil organic carbon (SOC), total soil nitrogen (TSN), and inorganic N (NO3- -N and NH4+ -N) at 0-3, 3-20, 20-40 and 40-60 cm depths, and calculated C and N pools in 0-20, 20-40, 40-60, and 0-60 cm soil layers. Compared with the adjacent secondary forests, shifting cultivation and establishment of rubber tree plantations resulted in significant decline in concentrations and stocks of SOC and TSN in 0-20 and 0-60 cm soil layers, and increase in pH and bulk density at 0-3, 3-20, and 20-40 cm depths. Soil moisture content decreased only in 0-20 cm surface soils in shifting cultivation and plantations. The dynamics of mineral N was much more complex, which had different trends among depths and ecosystems. Compared with the secondary forests, SOC stocks in 0-20 cm surface soils in shifting cultivation and rubber tree plantations (3-year-old plantation and 7-year-old plantation) decreased by 34.0%, 33%, and 23%; and TSN stocks decreased by 32.2%, 20.4%, and 20.4%, respectively, whereas the decreases of SOC and TSN stocks in 0-60 cm soil layers were much less. The results indicated that C and N losses were mainly occurred in 0-20 cm surface soil, followed by 20-40 cm layer.

[An outbreak of SARS in Dongcheng District, Beijing during March to June 2003].

OBJECTIVE: To describe epidemiological characteristics of an outbreak of severe acute respiratory syndrome (SRAS) in Dongcheng District, Beijing during March to June 2003. METHODS: Data of SARS cases notified from Dongcheng District Center for Disease Control and Prevention (CDC) and supplemented by other channels were collected. All data were input into dataset files by Microsoft Excel-2000 software and analyzed with SPSS version 10.0 software. RESULTS: Totally, 572 cases notified were collected during this period in Dongcheng District, Beijing, and 99 of them were excluded from SARS, because of diagnosis of common cold, pneumonia, measles, or rubella, etc. Actually, 473 SARS cases were analyzed. Attack rate of SARS in permanent residents of Dongcheng was 28.3 per 100,000. Forty-one of them died, with a case-fatality ratio of 8.7%. Outbreak of SARS in Dongcheng District started on March 14, with a peak during mid- and late April, and dropped from May 5, 2003. Persons were all susceptible to SARS, with the highest proportion at ages of 20-50 years, which accounted for 68.7% of the total cases. Average age of the patients at their onset was 40.7 years. No gender difference in SARS cases was found. Number of SARS cases in health care workers (HCWs) accounted for 18.0% and that in the retired persons accounted for 15.4% of the total cases. Cases occurred in all 10 sub-districts of Dongcheng. Totally, 230 of the 572 notified cases (40.2%) hospitalized at local hospitals under the jurisdiction of Dongcheng District. Eighteen of 85 cases of SARS occurred in health care workers of local hospitals, accounting for 4.5% of the total number of health care workers working at the wards caring for SARS patients or at fever clinics. There were 34.7% of SARS cases without any contact histories before their onset. Familial aggregation phenomena were observed in 41.8% of the cases and 18.1% of households. And, 7.4% (attack rate) in those exposed to SARS cases suffered the illness during the periods of quarantine. CONCLUSIONS: SARS appeared outbreak in Dongcheng District, Beijing during March to June 2003. People were all susceptible to SARS, which mainly threatened the young adults and the middle-aged, as well as health care workers and the retired workers. Main mode of transmission was exposure to SARS patients in a near distance at hospitals or families. Prevention and control of SARS should be focused on early isolation of patients and quarantine for the contacts. Current available measures to prevent and control SARS proved effective.

Epidemiological characteristics of an outbreak of severe acute respiratory syndrome in Dongcheng District of Beijing from March to May 2003.

OBJECTIVE: To describe epidemiologic features of an outbreak of severe acute respiratory syndrome (SARS) in Dongcheng District, Beijing occurred in a period between March and May 2003. METHODS: Data of SARS cases notified from Dongcheng District Center for Disease Control and Prevention(CDC)and supplemented by other channels were collected. Clinicians and officials of local hospitals were interviewed in groups and medical records of fatal cases of SARS were reviewed to verify the diagnosis. Stored serum specimens of the patients were detected for IgG antibody against SARS Co-V by enzyme-linked immunosorbent assay (ELISA). All the data were input into dataset files by Microsoft Excel-2000 software and analyzed with SPSS version 10.0 software. RESULTS: Outbreak of SARS in Dongcheng District started on March 14, 2003 with a peak in mid- and late April, and dropped in early May. A total of 572 reported cases were collected during this period in Dongcheng District, Beijing, and 99 of them were excluded from SARS, because of diagnosis of common cold, regular pneumonia, measles and rubella, etc. Actually, 473 SARS cases, which included 390 (82.5%) probable cases and 83 (17.5%) suspect cases, were analyzed. About 90% of the probable cases were positive for IgG antibody. Attack rate of SARS in permanent residents of Dongcheng District was 28.3 per 100 000. Forty-one of them died, with a case-fatality rate of 8.7%. Persons were all susceptible to infection of SARS Co-V, with the highest proportion at ages of 20-50 years, which accounted for 68.7% of the total cases. Average age of the patients at their onset was 40.7 years. No gender difference in SARS cases was found. Number of SARS cases in health-care workers (HCWs) accounted for 18.0% and that in retired workers accounted for 15.4% of the total cases. Cases occurred in all 10 sub-districts of Dongcheng, with the highest in Beixinqiao and Andingmen Sub-districts. Totally, 230 of the 572 notified cases (40.2%) were hospitalized at local hospitals under the jurisdiction of Dongcheng District. Eighteen of 85 cases of SARS occurred in HCWs of local hospitals, accounting for 4.5% of the total number of HCWs working at wards caring for SARS patients or fever clinics. There were 34.7% of SARS cases without any histories of contact before the onset of the disease. Familial aggregation phenomena were observed in 41.8% of the cases and 18.1% of households. And 7.4% (attack rate) of those exposed to SARS cases suffered from the illness during the periods of quarantine. CONCLUSIONS: SARS appeared to be infectious in origin and caused outbreak in Dongcheng District, Beijing introduced by an imported case traveling from Hong Kong in a period between March and May 2003. People are all susceptible to infection of SARS Co-V, which mainly threatens the young adults and the middle-aged, as well as HCWs and the retired workers. The main mode of transmission is direct exposure to SARS patients in a near distance at hospitals or families via droplets spread. Prevention and control of SARS should be focused on early isolation of patients and quarantine for close contacts. Current available measures to prevent and control SARS are proved to be effective.