Heating conversion of indole-3-carbinol into N-substituted oligomers with anti-melanoma effect.

Cruciferous vegetables (CVs) are globally consumed with some health benefits believed to arise from indole-3-carbinol (I3C), a labile phytochemical liberated from indole glucosinolates, but few reports describe the effect of cooking on I3C reactions. Here, we present heat-promoted direct conversions of I3C in broccoli florets into indole derivatives, which are unique in the N-indolylmethylation and -hydroxymethylation of indole nuclei by 3-methyleneindole and formaldehyde formed in situ from the I3C dehydration and the dimerization of I3C to 3,3'-diindolylmethane (DIM), respectively. Such N-substituted indoles were found in a range of 0.4-4.6 µg per gram of steamed broccoli florets, with a novel compound N-(indol-3-ylmethyl)-3,3'-diindolylmethane (DIM-1) bio-evaluated to inhibit A375 cells with an IC50 value of 1.87 µM. In aggregation, the investigation discloses the promoting effect of heating on the I3C transformation in CVs and identifies DIM-1 as an anti-cancer drug candidate, and thus updates the knowledge of I3C and bioactive derivatives thereof.

The interaction of breath holding and muscle mechanoreflex on cardiovascular responses in breath-hold divers and non-breath-hold divers.

Cardiovascular responses to diving are characterized by two opposing responses: tachycardia resulting from exercise and bradycardia resulting from the apnea. The convergence of bradycardia and tachycardia may determine the cardiovascular responses to diving. The purpose of this study was to investigate the interaction of breath holding and muscle mechanoreflex on cardiovascular responses in breath-hold divers (BHDs) and non-BHDs. We compared the cardiovascular responses to combined apnea and the mechanoreflex in BHDs and non-BHDs. All participants undertook three trials-apnea, passive leg cycling (PLC), and combined trials-for 30 s after rest. Cardiovascular variables were measured continuously. Nine BHD (male:female, 4:5; [means ± SD] age, 35 ± 6 years; height, 168.6 ± 4.6 cm; body mass, 58.4 ± 5.9 kg) and eight non-BHD (male:female, 4:4; [means ± SD] age, 35 ± 7 years; height, 163.9 ± 9.1 cm; body mass, 55.6 ± 7.2 kg) participants were included. Compared to the resting baseline, heart rate (HR) and cardiac output (CO) significantly decreased during the combined trial in the BHD group, while they significantly increased during the combined trials in the non-BHD group (P < 0.05). Changes in the HR and CO were significantly lower in the BHD group than in the non-BHD group in the combined trial (P < 0.05). These results suggest that bradycardia with apnea in BHDs is prioritized over tachycardia with the mechanoreflex, whereas that in non-BHDs is not. This finding implies that diving training changes the interaction between apnea and the mechanoreflex in cardiovascular control.

Toxic effects of permethrin on HMC3 microglia and its associated mechanism / 环境与职业医学

Background Permethrin is a commonly used pyrethroid insecticide and has been found to be potentially neurotoxic. Microglia are innate immune cells in the central nervous system and are involved in the development of a range of neurodegenerative diseases. Objective To observe possible toxic effects of permethrin on human microglia clone 3 (HMC3) in vitro and explore associated mechanism. Methods HMC3 were treated with 0, 10, 25, and 55 μmol·L−1 permethrin for 72 h. Cell cycle and apoptosis were measured using flow cytometry. Cyclin-dependent kinase 1 (CDK1), cyclin-dependent kinase inhibitor 1A (CDKN1A), cyclin B2 (CCNB2), cellular tumor antigen p53 (p53), factor-related apoptosis (FAS), caspase 3 (CASP3), and H2A histone family member X (H2AX) were detected by quantitative real-time PCR (qPCR). The differential genes and enrichment pathways of HMC3 after 0 and 25 μmol·L−1 permethrin treatment was analyzed by RNA sequencing. HMC3 was treated by 0, 10, 25, and 55 μmol· L−1 permethrin for 72 h. The content of nitric oxide (NO) in the supernatant was detected using Griess reagent. The secretion level of interleukin-6 (IL-6) was detected by enzyme linked immunosorbent assay (ELISA). The mRNA expression levels of mitogen-activated protein kinase (MAPK) pathway (including MAPK1, MAPK8, and MAPK14), interleukin-1β (IL-1β), IL-6, and matrix metalloproteinase (MMP) families (including MMP1, MMP2, MMP3, and MMP9) were detected by qPCR. The protein expressions of phosphorylated p38 mitogen-activated protein kinase (p-p38), phosphorylated extracellular signal-regulated kinase (p-ERK), IL-1β, IL-6, and MMP1 were detected by Western blot. Results HMC3 was arrested in G2/M phase after 0, 10, 25, and 55 μmol·L−1 permethrin treatment for 72 h, of which there was a statistically significant difference between the 55 μmol·L−1 permethrin treatment group and the control group (P<0.01), and the mRNA expression of CDKN1A was up-regulated according to the qPCR (P<0.05). There was no statistically significant difference in the proportions of apoptosis between the groups (P＞0.05). The RNA sequencing showed that the differential genes were enriched in the MAPK pathway, and the mRNA expressions of MAPK1, MAPK8, and MAPK14 were up-regulated after the permethrin treatment at 55 μmol·L−1 compared to the control group by qPCR (P<0.05). The Western blot revealed that, compared to the control group, the levels of p-p38 and p-ERK were increased after the 10 μmol·L−1 permetrin treatment (P<0.05), the p-ERK level was increased after the 25 μmol·L−1 permetrin treatment (P<0.05), and the p-p38 level was up-regulated after the 55 μmol·L−1 permetrin treatment (P<0.05). The secretion of NO in the supernatant of HMC3 increased after permetrin treatment compared to the control group (P<0.05), the mRNA and protein expressions and the secretion of IL-6 showed an upward trend, the mRNA and protein expressions of IL-1β were up-regulated (P<0.05), and the mRNA and protein expressions of MMP1 were up-regulated in the 25 and 55 μmol·L−1 permethrin groups (P<0.05). Conclusion Permethrin inhibits HMC3 cell proliferation in vitro, induces cell cycle arrest, activates MAPK pathway, and promotes the expression of inflammatory factors IL-1β and MMP1, which may be one of the mechanism of neurotoxicity induced by permethrin.

Muscle stretching induces the mechanoreflex response in human arterial blood pressure.

The muscle mechanoreflex has been considered to make a small contribution to the cardiovascular response to exercise in healthy humans because no pressor response has been observed during stimulation of mechanosensitive receptors, such as static passive stretching, during many human studies. There is room for rethinking this consideration since the pressor response to upper limb exercise is greater than that to lower limb exercise. We examined whether static passive stretching of the forearm muscles causes a muscle mechanoreflex-induced pressor response in humans. Eighteen healthy men were recruited for this study. After a 15-min rest period in the supine position with a neutral (0°) wrist joint angle, all participants completed static passive stretching of the forearm for 60 s at four different intensities: minimal painful passive stretching (PPS), moderate-intensity passive stretching (MPS), low-intensity passive stretching (LPS), and no load (NL). During the procedure, beat-to-beat arterial blood pressure was measured using finger photoplethysmography. The force generated between the passively stretched hand and the experimenter's hands was recorded using a force transducer. Mean arterial pressure (MAP) during PPS and MPS significantly increased from baseline during the last 40 s (P < 0.05). MAP was significantly greater at 50 s and 60 s, depending on the intensity. MPS induced a greater peak response in MAP than lower intensities (P < 0.05). None of the subjects reported pain during the MPS and LPS trials. Static passive stimulation of the forearm is an effective method of isolating the muscle mechanoareflex-induced pressor response in humans.NEW & NOTEWORTHY The muscle mechanoreflex was considered to have a small contribution to cardiovascular regulation during exercise in healthy humans. In contrast, the results of this study indicate that static stretching of the forearm induces a pressor response in healthy humans and suggest that the mechanoreflex explicitly induces the pressor response during exercise in humans. The methods applied are useful for evaluating the pressor response to the mechanoreflex regardless of health, aging, and disease.

Cryptic COL1A1-PDGFB fusion in dermatofibrosarcoma protuberans: a clinicopathological and genetic analysis / 中华病理学杂志

Objective: To investigate the clinicopathological and cytogenetic features of cryptic COL1A1-PDGFB fusion dermatofibrosarcoma protuberans (CC-DFSP). Methods: Three cases of CC-DFSP diagnosed in West China Hospital, Sichuan University, Chengdu, China from January 2021 to September 2021 were studied. Immunohistochemistry for CD34 and other markers, fluorescence in situ hybridization (FISH) for PDGFB, COL1A1-PDGFB and COL1A1, next-generation sequencing (NGS), reverse-transcriptase polymerase chain reaction (RT-PCR) and Sanger sequencing were performed. Results: There were three cases of CC-DFSP, including two females and one male. The patients were 29, 44 and 32 years old, respectively. The sites were abdominal wall, caruncle and scapula. Microscopically, they were poorly circumscribed. The spindle cells of the tumors infiltrated into the whole dermis or subcutaneous tissues, typically arranging in a storiform pattern. Immunohistochemically, the neoplastic cells exhibited diffuse CD34 expression, but were negative for S-100, SMA, and Myogenin. Loss of H3K27me3 was not observed in the tumor cells. The Ki-67 index was 10%-15%. The 3 cases were all negative for PDGFB rearrangement and COL1A1-PDGFB fusion, whereas showing unbalanced rearrangement for COL1A1. Case 1 showed a COL1A1 (exon 31)-PDGFB (exon 2) fusion using NGS, which was further validated through RT-PCR and Sanger sequencing. All patients underwent extended surgical resection. Except for case 3 with recurrence 2 years after surgical resection, the other 2 cases showed no recurrence or metastasis during the follow-up. Conclusions: FISH has shown its validity for detecting PDGFB rearrangement and COL1A1-PDGFB fusion and widely applied in clinical detection. However, for cases with negative routine FISH screening that were highly suspicious for DFSPs, supplementary NGS or at least COL1A1 break-apart FISH screening could be helpful to identify cryptic COL1A1-PDGFB fusions or other variant fusions.

Muscle stiffening is associated with muscle mechanoreflex-mediated cardioacceleration.

PURPOSE: Although the muscle mechanoreflex is an important mediator to cardiovascular regulation during exercise, its modulation factors remain relatively unknown. Therefore, the purpose of this study was to investigate the effect of muscle stiffness on the muscle mechanoreflex. METHODS: Participants were divided based on their median muscle stiffness (2.00 Nm/mm) into a low group (n = 15) and a high group (n = 15), and the muscle mechanoreflex was compared between the groups. After a 15-min rest in the supine position, heart rate (HR), blood pressure (BP), stroke volume (SV), and cardiac output (CO) were measured at rest for 3 min and during static passive dorsiflexion (SPD) at 20° for 1 min. Following a 15-min re-rest, muscle stiffness and passive resistive torque were evaluated in the distal end of the muscle belly of the medial gastrocnemius. RESULTS: Peak relative changes in HR (low group: 6 ± 4% and high group: 12 ± 4%) and CO (low group: 8 ± 10% and high group: 13 ± 9%) were greater in the high group than in the low group (both, P < 0.05). A significant positive correlation was found between resistive torque during SPD and muscle stiffness and peak relative changes in HR (r = 0.51 and 0.61, both P < 0.05). However, there was no correlation between muscle elongation during SPD and peak relative changes in HR (r = - 0.23, P = 0.20). CONCLUSION: These findings suggest that muscle stiffness may be modulatory factor of muscle mechanoreflex.

[Spatiotemporal Variations in Nutrient Loads in River-lake System of Changdang Lake Catchment in 2016-2017].

Eutrophication of shallow lakes in the middle and lower reaches of the Yangtze River has become an increasingly serious problem. In this study, we investigated the temporal and spatial variations in nutrient loads (nitrogen, N and phosphorus, P) in the Changdang Lake Catchment located to the northwest of Lake Taihu through field sampling and laboratory analysis in 2016-2017. The results show the severity of the N and P pollution in the Changdang Lake catchment. The mean river water concentrations of TN, NO3--N, NH4+-N, TP, Chla, and permanganate index are (3.70±0.76) mg ·L-1, (1.81±0.42) mg ·L-1, (1.03±0.61) mg ·L-1, (0.38±0.31) mg ·L-1, (25.74±37.00) µg ·L-1, and (6.35±0.81) mg ·L-1, respectively. N pollution in the river is more severe in winter and spring than in summer and autumn whereas P pollution in the river is worse in autumn and winter than in spring and summer. Spatially, the magnitude of river N and P pollution follows the order of northern > northwestern > southern > eastern part of the study area. The rivers are in a state of moderate to severe eutrophication. The mean lake water concentrations of TN, NO3--N, NH4+-N, TP, Chla, and permanganate index are (2.25±0.94) mg ·L-1, (0.98±0.47) mg ·L-1, (0.19±0.14) mg ·L-1, (0.11±0.03) mg ·L-1, (18.71±8.76) µg ·L-1, and (4.59±1.09) mg ·L-1, respectively. The water quality in Changdang Lake is categorized as worse than class Ⅲ for TN and TP concentrations, which show decreasing trends from the west to the east to the south of the lake. The lake is in a status of slight to moderate eutrophication. The lake water quality is affected by the combination of sewage discharge and non-point source pollutant losses. The inflow rivers including the Danjinlicao River, Tongji River, and Xuebu River are the dominant pollution sources for Changdang Lake. The Danjinlicao River transports 10-12 times the total N and P loads transported by Tongji and Xuebu rivers. Changes in land use and atmospheric deposition are the driving factors of the deterioration of water quality and eutrophication in the catchment.

Lecithin doped electrospun poly(lactic acid)-thermoplastic polyurethane fibers for hepatocyte viability improvement.

The development of hepatocyte cultures in vitro holds great significance in the study of bioartificial liver support systems. Electrospun fiber cultures have received widespread attention as an effective method to culture hepatocytes in vitro. Polylactic acid (PLA) -a synthetic polymer with high biocompatibility and biodegradability- is widely used to fabricate electrospun fibers in the biomedical field. However, the use of PLA is limited in cell cultures due to its brittleness, strong hydrophobicity, and lack of biologically active functional groups. In this study, thermoplastic polyurethane (TPU) and lecithin (Lec) were used to modify PLA by spiking them into the PLA electrospun solution in attempt to establish a suitable fiber scaffold for hepatocyte culture in bioreactors. TPU and lecithin incorporation into PLA increases the flexibility, hydrophilicity, and biologically active groups of the fibers which further promotes the growth, proliferation, and viability of hepatocytes. The morphology, wettability, and biocompatibility of the as-prepared PLA-TPU-Lec fibers were carefully characterized. The results showed that the PLA-TPU-Lec fibers possessed favorable morphology and hydrophilicity, as well as high biocompatibility ability. HepG2 cells on the PLA-TPU-Lec fibers and tissue culture plates (TCP) were exposed to hepatotoxins for 24 h and we found that HepG2 cells on the PLA-TPU-Lec fibers had higher viability than cells on TCP. The PLA-TPU-Lec fibers are therefore expected to be used in vitro for hepatocyte culture to improve cellular activity in artificial liver bioreactors.

Preparation and study of the antibacterial ability of graphene oxide-catechol hybrid polylactic acid nanofiber mats.

The functionalization of electrospun mats with antimicrobial nanomaterials is an attractive strategy when developing functional graphene oxide coating materials to prevent bacterial colonization on surfaces. In this study, we demonstrated a simple approach to produce antimicrobial electrospun mats by dip-coating a polylactic acid (PLA) nanofiber into a graphene oxide-catechol derivative. PLA was first electrospun to yield narrow-diameter polymeric nanofibers. We then modified the graphene oxide (GO) with a catechol derivative - dopamine methacrylamide monomer (DMA) - to synthesize a GO-DMA nanocomposite material which exhibited robust antimicrobial properties. The catechol groups promote the immobilization of graphene oxide onto the PLA nanofibers and possess strong antimicrobial properties. We therefore selected this functional group to modify GO. We dipped the GO-DMA onto the PLA nanofiber to produce the final functionalized electrospun mats. The PLA mats which were functionalized using the GO-DMA nanocomposite (PLA-GO-DMA) displayed antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Furthermore, we studied the biocompatibility of the mats by culturing the cell lines (HepG2, A549, and HUVEC-C) of PLA-GO-DMA among the nanofibers which exhibited excellent biocompatibility. These results collectively demonstrate the potential of PLA-GO-DMA nanofiber mats as antimicrobial biomaterials and provide fundamental information toward the establishment of future biomedical applications.

[Thermal Stratification and Its Impacts on Water Quality in Shahe Reservoir, Liyang, China].

Based on the one-year hourly water temperature profiles and the associated environmental drivers during the past eight years in Shahe Reservoir, Jiangsu Province, China from 2009 to 2016, the factors underlying the seasonal variation of thermal stratification and water quality response were investigated. It was shown that the thermal stratification was a typical subtropical one-cycle mixing model, lasting from May to September. The thermal stratification appeared and disappeared when the surface water temperature was 21 ℃ in the late spring and 19 ℃ in the middle of autumn. The difference between the water temperature at the epilimnion and hypolimnion increased with increasing solar radiation. When the air temperature was above 30 ℃, the stability of the thermal stratification increased. Heavy storms reduced the temperature of the surface water and weakened the temperature stratification of the column above a 5 m depth but had limited impact on the stratification of the hypolimnion deeper than 5 m. The thermal stratification greatly impacted the water quality of the lake. Hypoxia in the bottom water occurred by thermal stratification, leading to increased NH4+-N. The concentrations of dissolved oxygen, total phosphorus, and suspended solids in the hypolimnion increased after the disappearance of thermal stratification. Our results indicated that the thermal stratification was mainly controlled by solar radiation and the thermal stratification favored the growth of cyanobacteria and led to the release of nutrients from the sediment, threatening the water quality. Attention should be paid to thermal stratification to prevent algal blooms and related water quality deterioration.

Basic and clinical research progress in pulmonary alveolar microlithiasis / 医学研究生学报

Pulmonary alveolar microlithiasis (PAM) is a rare genetic disease characterized by calcifications within the alveoli in the lung. Mutations in SLC34A2 gene, which encodes a type IIb sodiumphosphate cotransporter, are responsible for PAM, leading to the intra-alveolar accumulation of phosphate which favors the formation of microliths. A "sandstorm" appearance is the typical radiographic presentation of PAM. The hallmark of this disorder is clinical-radiological dissociation, with typical imaging findings, specific pathological findings and closely correlated specific genetic mutations. The disease has an insidious onset, runs a chronic course and the prognosis is poor. There is no effective treatment except for lung transplantation. This article summarizes the epidemiology, molecular genetics and clinical features of pulmonary alveolar calculi.

[Investigation of two blood parasitic protozoa infection in farmed Macaca fascicularis in Guangxi Zhuang Autonomous Region].

OBJECTIVE: To investigate the infection situation of blood parasitic protozoa in farmed Macaca fascicularis in an animal breeding ground in Nanning, Guangxi Zhuang Autonomous Region, so as to provide the evidence for the prevention and control of human blood parasitic protozoa. METHODS: A total of 993 blood samples from farmed M. fascicularis were collected and stored on FTA cards. Among them, 550 thin blood smears were made. Each 10 samples were mixed in groups, and then the Babesia spp. and Plasmodium spp. in the blood of M. fascicularis were detected by Nest-PCR and PCR, respectively. The positive groups were tested individually. The thin blood smears stained with Giemsa were examined microscopically when PCR reported the samples were positive. RESULTS: When detected by Nest-PCR, the positive rate of Babesia. microti was 6.95% (69/993); only 1 positive sample with Plasmodium inui was detected by PCR. Among the 22 positive thin blood smears detected by PCR, 16 were determined with B. microti by microscopic examinations, on which the ring forms could be observed in the erythrocytes, but no hemozoin. CONCLUSIONS: The positive rate of B. microti in M. fascicularis in Guangxi Zhuang Autonomous Region is high, and the animal may play a role as a reservoir host in the transmission of B. microti. In the screening of B. microti with low infection density, Nest-PCR has a higher sensitivity.

[Impact on nitrogen and phosphorous export of wetlands in Tianmu Lake watershed].

Focused on understanding the function of wetland in improving water quality, Pingqiao watershed and Zhongtian watershed in Tianmu Lake drinking water sources area were selected as the research region. We integrated remote sensing, GIS techniques with field investigation and chemical analysis to analyze the relationship between wetland and water quality in watershed scale. Results show: (1) There are many wetland patches in Pingqiao and Zhongtian watershed, wetlands patch densities were respectively 7.5 km(-2) and 7.1 km(-2). Wetlands widely distributed in the Pingqiao watershed with mostly located away from the river of 500 m, whereas wetlands relatively concentrated in the lower reach within 500 meters of riverside in Zhongtian watershed. (2) Nitrogen and phosphorus nutrient retention of wetland in watershed scale was significant. The annual mean TN and DTN concentration had a strong relationship with percent area of wetlands in Zhongtian watershed while the weakest relationship was found with TP and DTP concentrations, especially, the mean TN and DTN concentrations in spring and winter had the significantly negative relationship with wetland areas of watershed. The negative relationship was existed for nitrogen in autumn of Pingqiao watershed, which suggested that watersheds varying in area of wetlands have the different nutrient reducing efficiency in seasonal periods. (3) A certain number and area of wetland will improve river water quality in watershed scale, which can instruct water environment treatment. However, considering the complexity of nutrient transport processes in watershed, wetland-related factors such as area, location, density, ecosystem structure and watershed-related factors such as temporal interval, spatial scales, slope and land use will impact on the transport processes, and related theoretical and practical problems need further research.

A multivariate analysis of prognostic determinants for stages II and III colorectal cancer in 141 patients / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Previous prognosis analyses of colorectal cancer (CRC) patients with stage II and III disease were done as separate categories. The purpose of this study was to analyze prognostic factors associated with survival in a group of patients who underwent radical resection of stages II and III CRC.</p><p><b>METHODS</b>A retrospective review was performed for 141 consecutive stages II and III patients who had undergone radical resection of colorectal adenocarcinoma between May 2003 and November 2003. Univariate and multivariate analyses were performed to assess the effect of record variables on disease free survival and overall survival.</p><p><b>RESULTS</b>The median follow-up time was 59 months, and the 3- and 5-year survival rates were 76% and 68%, respectively. Four factors were independently associated with a worse disease-free survival: diabetes (hazard ratio (HR) 2.338; 95% confidence interval (CI) 1.011 - 5.407), expression of cyclooxygenase-2 (Cox-2) (HR 0.335; 95%CI 0.126 - 0.888), expression of matrix metalloproteinases 2 (MMP-2) (HR 0.233; 95%CI 0.101 - 0.541), expression of vascular endothelial growth factor (VEGF) (HR 0.295; 95%CI 0.088 - 0.996). Four factors were independently associated with a worse overall survival: lymph nodes metastasis (HR 1.67; 95%CI 1.29 - 2.14), Cox-2 positive (HR 0.056; 95%CI 0.247 - 0.731), MMP-2 positive (HR 0.398; 95%CI 0.190 - 0.836), VEGF (HR 0.364; 95%CI 0.090 - 0.716).</p><p><b>CONCLUSIONS</b>Diabetes, expression of Cox-2, MMP-2 and VEGF were independently associated with a worse disease- free survival. Lymph nodes metastasis, expression of Cox-2, MMP-2 and high level of VEGF predicted a poor overall survival.</p>

[Impacts on nutrient export by landscape heterogeneity based on sub-watershed].

Landscape features of a watershed are important factors affecting non-point source (NPS) pollution. Sub-watershed bounds were delineated and landscape heterogeneity was analyzed based on GIS and RS in Xitiaoxi watershed which located the upper reach of Taihu Lake area. Nutrient export intensity of sub-watersheds was estimated by revised export coefficient model. Then the relationships between nutrient export and main landscape types, as well as Shannon diversity index (SHDI) in sub-watershed units were analyzed. Results show, TN and TP export intensity have obvious spatial difference, which changed from 3.01 kg/(hm2 x a) to 15.44 kg/(hm2 x a) and 0.049 kg/(hm2 x a) to 0.355 kg/(hm2 x a) respectively. The dominated landscape types including cultivated land and forest land quantitatively related with nutrient export intensity. TN and TP export intensity will decrease 0.203 1 kg/(hm2 x a) and 0.0152 kg/(hm2 x a) respectively with 10% increased of forest area, and will increase 0.5726 kg/(hm2 x a) and 0.0273 kg/(hm2 x a) with 10% increased of cultivated land area. The relationship between nutrient export intensity and SHDI exhibited second-degree polynomial, export intensity increased by SHDI increasing and to maximum when SHDI equals 1.5, then decreased with SHDI increasing. This research results will provide an important reference value for NPS management.

[Spatio-temporal changes of nitrogen balance in 1980-2005 for agricultural land in Three Gorges Reservoir Area].

Based on the long-term agricultural statistics data at the county scale, the estimation of nitrogen balance from 1980 to 2005 for agricultural land in Three Gorges Reservoir Area was made by the OECD soil surface nitrogen balance model with some suitable modification. The spatio-temporal changes of nitrogen balance and its drivers were analyzed. The results showed that the total inputs and total surplus of nitrogen from 1980 to 2005 presented increasing trends continuously, from 23.4 x 10(4) t and 14.4 x 104 t to 45.6 x 10(4) t and 30 x 10(4) t respectively. The total output of nitrogen in 1980-1995 was at the increasing trend, from 9.0 x 10(4) t to 16.7 x 10(4) t, while that of 1996-2005 was keeping steady. The average unit surplus of nitrogen in 1980-1998 was also at the increasing trend, from 133.4 kg/hm2 to 310.3 kg/hm(2); and the trend inclined to be steady after 1998, while the spatial differential pattern toned up. The great spatial changes for nitrogen surplus from 1980 to 2005, mainly centralized at the head and the middle of the Three Gorges Reservoir Area, similar to the spatial distribution of the resettlement. Fertilizer, manure and biological fixation were the main contributors of nitrogen input sources, accumulatively totaled for above 90%. Nitrogen balance changes were mainly influenced by the macro-environment of fertilizer utilization before 1995, while which were influenced by the large amounts of the resettlement for Three Gorges Project after 1995. However, how much the effects of the resettlement on nitrogen balance need to be further explored. Developing sideline, agricultural structure transition or ecological resettlement should be considered to control nitrogen emission.

[Estimated nutrient export loads based on improved export coefficient model in Xitiaoxi watershed].

It is very important to estimate nutrient export loads from watershed, which is beneficial to water environmental management. The export coefficients for major land use types were evaluated by field surveying data, in addition the spatial distributions of precipitation and runoff were considered, to improve on export coefficient model (ECM), then integrated ECM into geographical information system to compose half-distribution model of export coefficients. Estimated nutrients export loads based on the ECM in Xitiaoxi watershed located upper of Taihu Lake area. Results show that the export load for TN and TP was 2 121.3 t and 49.3 t respectively, which provides important reference value for nonpoint source pollution management.

[Influence of landscape characteristics on non-point source pollutant output in Taihu upper-river basin].

Based on the observed data in monitored drainage areas and GIS spatial analysis tools, watershed basic database of Taihu upper-river basin was built. Using the methods of multiple stepwise regression and redundancy analysis, the influence of landscape characteristics on non-point source pollutant output at the outlets of watersheds and their relative influence intensity were analyzed. The dominant landscape characteristics influencing non-point source pollutant output in Taihu upper-river basin and sub-watersheds were also illustrated. The results show that there are strong correlations between non-point source pollution and landscape characteristics, in which land use makes the most remarkable effect, followed by soil characteristics and average slope and watershed area in turn. Residential land proportion, farmland proportion and average terrain slope with higher importance and significance level, are the dominant landscape characteristics variables affecting non-point source pollutant output of watersheds. 59.5% of water quality information and 98.6% of relation information between landscape characteristics and water quality can be explained by these three variables. Furthermore, the contribution rates of these three landscape characteristics to non-point source pollutant output in each sub-watershed are different.

Suppression of phosphate liberation from eutrophic lake sediment by using fly ash and ordinary portland cement.

In this study, the effect of suppression on phosphate liberation from eutrophic lake sediment by using fly ash and ordinary Portland cement (OPC) was investigated by small scale experiment. A system including sediment, lake water, and several kinds of capping materials was designed to clarify the suppression of phosphate liberation from sediment under the anaerobic condition. The suppression efficiencies of fly ash, OPC and glass bead used as control material were also determined, and these effects were discussed. The suppression efficiency of glass bead was 44.4%, and those of fly ash and OPC were 84.4%, 94.9%, respectively. The suppression by fly ash and OPC was mainly carried out by the adsorption effect, in addition to the covering effect. The suppression efficiency depended on the amounts of the material used, and about 90% of liberated phosphate was suppressed by fly ash of 10.0 Kg m(-2), and OPC of 6.0 Kg m(-2). The concentrations of heavy metals, such as mercury, cadmium, lead, copper, zinc, chromium, silver, arsenic and nickel, in fly ash and OPC were lower than those in the environmental materials. And it was considered that the concentrations of heavy metals in fly ash and OPC were too low to influence the ecosystem in natural water region.

Cultivation of Pathogenic Free-living Amoebae / 中国寄生虫学与寄生虫病杂志

The isolation and culture of pathogenic free-living amoebae are useful in the diagnosis and research. This review focuses on the methods of isolation and cultivation of pathogenic free-living amoebae, including sample treatment, culture conditions, passage culture, pathogen detection, and maintenance.