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Yi Shi

Publications and source records attributed to Yi Shi.

At least 55 records · Page 3Linked to original sources
PubMed2004

[Accumulation of soil inorganic nitrogen in mono-harvesting farmlands in northeast China in late autumn].

The study showed that in northeast China, the farmlands with a mono-harvesting agricultural system had a low accumulation of soil inorganic nitrogen after harvest. In late autumn, there was an interval of about 20-30 days when the temperature and humidity were appropriate to soil N mineralization, but the mineralized nitrogen could not be used by crops in this non-growing season. The accumulation of inorganic nitrogen in upland soil reached a high level before freezing. Its inorganic nitrogen content in 1 m depth soil was 99.9 kg x hm(-2) in the treatment of commercial fertilizers (N 150 kg x hm(-2); P 16.4 kg x hm(-2); K 62.3 kg x hm(-2))and 145.4 kg x hm(-2) in the treatment of commercial fertilizers plus manure (pig manure by a reutilization of 80% product). While in rice field, its inorganic nitrogen content was relatively low before freezing. The reason might be that the soil permeability was not as good as that in upland for its long-term water-logging, and its insufficient aeration would be favorable to denitrification which induces the inorganic nitrogen loss via N2O emission.

China↗
PubMed2003

Human epicardial adipose tissue is a source of inflammatory mediators.

BACKGROUND: Inflammatory mediators that originate in vascular and extravascular tissues promote coronary lesion formation. Adipose tissue may function as an endocrine organ that contributes to an inflammatory burden in patients at risk of cardiovascular complications. In this study, we sought to compare expression of inflammatory mediators in epicardial and subcutaneous adipose stores in patients with critical CAD. METHODS AND RESULTS: Paired samples of epicardial and subcutaneous adipose tissues were harvested at the outset of elective CABG surgery (n=42; age 65+/-10 years). Local expression of chemokine (monocyte chemotactic protein [MCP]-1) and inflammatory cytokines (interleukin [IL]-1beta, IL-6, and tumor necrosis factor [TNF]-alpha) was analyzed by TaqMan real-time reverse transcription-polymerase chain reaction (mRNA) and by ELISA (protein release over 3 hours). Significantly higher levels of IL-1beta, IL-6, MCP-1, and TNF-alpha mRNA and protein were observed in epicardial adipose stores. Proinflammatory properties of epicardial adipose tissue were noted irrespective of clinical variables (diabetes, body mass index, and chronic use of statins or ACE inhibitors/angiotensin II receptor blockers) or plasma concentrations of circulating biomarkers. In a subset of samples (n=11), global gene expression was explored by DNA microarray hybridization and confirmed the presence of a broad inflammatory reaction in epicardial adipose tissue in patients with coronary artery disease. The above findings were paralleled by the presence of inflammatory cell infiltrates in epicardial adipose stores. CONCLUSIONS: Epicardial adipose tissue is a source of several inflammatory mediators in high-risk cardiac patients. Plasma inflammatory biomarkers may not adequately reflect local tissue inflammation. Current therapies do not appear to eliminate local inflammatory signals in epicardial adipose tissue.

Adipose Tissue↗
PubMed2003

Elevated plasma homocysteine was associated with hemorrhagic and ischemic stroke, but methylenetetrahydrofolate reductase gene C677T polymorphism was a risk factor for thrombotic stroke: a Multicenter Case-Control Study in China.

BACKGROUND AND PURPOSE: It is still controversial whether elevated plasma homocysteine and the C677T polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene are risk factors for stroke. The aim of the present study was to investigate the association between the 2 factors and stroke in Chinese in a large case-control study. METHODS: We recruited 1823 stroke patients (807 cerebral thrombosis, 513 lacunar infarction, 503 intracerebral hemorrhage) and 1832 controls. Total plasma homocysteine was determined by high-performance liquid chromatography. C677T polymorphism was genotyped by polymerase chain reaction and HinfI digestion. RESULTS: Total plasma homocysteine levels were significantly higher in cases than controls (median, 14.7 versus 12.8 micromol/L; P<0.001) and associated with an increased risk of 1.87-fold (95% confidence interval [CI], 1.58 to 2.22) for overall stroke, 1.72-fold (95% CI, 1.39 to 2.12) for cerebral thrombosis, 1.89-fold (95% CI, 1.50 to 2.40) for lacunar infarction, and 1.94-fold (95% CI, 1.48 to 2.55) for intracerebral hemorrhage. The C677T mutation of the MTHFR gene was positively correlated with plasma homocysteine levels in both controls (beta=0.250, P<0.001) and cases (beta=0.272, P<0.001) and more frequently in cases than in controls (47.0% versus 44.2%, P=0.017). The TT genotype was associated with an increased risk for overall stroke (odds ratio, 1.27; 95% CI, 1.04 to 1.56) and thrombotic stroke (odds ratio, 1.37; 95% CI, 1.06 to 1.78). CONCLUSIONS: The C677T polymorphism of the MTHFR gene was associated with increased risk of cerebral thrombotic stroke in Chinese. Total plasma homocysteine was correlated with both ischemic and hemorrhagic stroke, suggesting potential initiation of homocysteine-lowering therapy in this population.

Brain Ischemia↗
PubMed2003

Diabetes-induced oxidative stress and low-grade inflammation in porcine coronary arteries.

BACKGROUND: Multiple pathways contribute to accelerated coronary atherosclerosis in diabetics, including increased oxidative stress and inflammatory burden. Accordingly, the mechanisms of abnormal formation of reactive oxygen species and the changes in inflammatory gene expression were examined in diabetic coronary arteries. METHODS AND RESULTS: In pigs with streptozotocin-induced diabetes, superoxide formation was augmented in coronary media and adventitia because of increased NAD(P)H oxidase activity (3 months) accompanied by upregulated expression of its cytosolic subunit, p22phox. Diabetes-induced oxidative stress resulted in the inflammatory response in the adventitia (increased expression of interleukin-6, tumor necrosis factor-alpha, monocyte chemotactic protein-1, vascular cell adhesion molecule-1 [VCAM-1]) and in the media (VCAM-1). To examine the mechanisms of these changes, studies with isolated coronary fibroblasts were undertaken. Advanced glycation end products (AGEs), rather than glucose itself, upregulated expression of interleukin-6, VCAM-1, and monocyte chemotactic protein-1 mRNAs. These results were paralleled by increased interleukin-6 secretion (P<0.01) and augmented leukocyte adhesion to AGE-stimulated coronary cells (P<0.001). AGEs increased expression of phosphorylated forms of mitogen-activated protein kinases in coronary cells (ERK1/2 and JNK) and resulted in redox-sensitive expression of inflammatory genes that was inhibited by several inhibitors of oxidative pathways [NAD(P)H oxidase inhibitors, N-acetylcysteine, and pyrrolidine dithiocarbamate]. CONCLUSIONS: Diabetes increased NAD(P)H oxidase activity and oxidative stress, producing inflammatory responses in porcine coronary media and adventitia. AGEs activated ERK1/2 and JNK signaling pathways and induced the expression of several inflammatory genes in coronary cells in a redox-sensitive manner. These results suggest the involvement of AGEs in the development of accelerated coronary atherosclerosis in diabetes.

Animals↗
PubMed2003

[A low level of TNF-mediates hemorrhage-induced acute lung injury via p55 TNF receptor].

OBJECTIVE: To examine the temporal relationship of pulmonary TNF-alpha production to acute lung injury (ALI) during hemorrhagic shock (HS). METHODS: HS was induced in mice by removal of 30% of calculated total blood volume. Lung TNF-alpha was measured by ELISA. Lung neutrophil accumulation was detected by immunofluorescent staining, and pulmonary microvascular permeability was assessed using Evans blue dye. RESULTS: While HS induced a slight and transient increase in lung TNF-alpha, neutrophil accumulation preceded the change in lung TNF-alpha. However, lung neutrophil accumulation and the increase in microvascular permeability were abrogated in TNF-alpha knockout mice, and both were restored by administration of low dose TNF-alpha to TNF-alpha knockout mice prior to HS. Both neutrophil accumulation and microvascular leak were abrogated in p55 TNF-alpha receptor knockout mice, while p75 TNF-alpha receptor knockout mice behaved similar to wild type. CONCLUSION: A low level of pulmonary TNF-alpha is sufficient to mediate HS-induced acute lung injury and that the p55 TNF-alpha receptor plays a dominant role in regulating the pulmonary inflammatory response to HS. The results suggest that anti-TNF-alpha strategies for the control of the pulmonary inflammatory response to HS can be directed toward antagonizing the p55 TNF-alpha receptor.

Animals↗
PubMed2003

TLR4 mediates LPS-induced HO-1 expression in mouse liver: role of TNF-alpha and IL-1beta.

AIM: Heme oxygenase (HO)-1 catalyzes the conversion of heme to biliverdin, iron and carbon monoxide. HO-1 is induced by many stimuli including heme, Hb, heat stress,lipopolysaccharide (LPS) and cytokines. Previous studies demonstrated that LPS induced HO-1 gene activation and HO-1 expression in liver. However, the mechanisms of LPS-induced HO-1 expression in liver remain unknown. The effect of toll-like receptor-4 (TLR4) on LPS-induced liver HO-1 expression and the role of TNF-alpha and IL-1beta in this condition were determined. METHODS: HO-1 expression was determined by immunofluorescent staining and immunoblotting. Double immunofluorescent staining was performed to determine the cell type of HO-1 expression in liver. RESULTS: A low dose of LPS significantly increased HO-1 expression in the liver which was localized in Kupffer cells only. Furthermore, HO-1 expression was enhanced by three doses of LPS. HO-1 expression was significantly inhibited in the liver of TLR4 mutant mice. While the liver HO-1 expression in TNF KO mice was much lower than that in C57 mice following the same LPS treatment, IL-1beta KO had a slight influence on liver HO-1 expression following LPS treatment. CONCLUSION: The present results confirm that macrophages are the major source of HO-1 in the liver induced by LPS. This study demonstrates that TLR4 plays a dominant role in mediating HO-1 expression following LPS. LPS-induced HO-1 expression is mainly mediated by endogenous TNF-alpha, but only partially by endogenous IL-1beta.

Animals↗
PubMed2003

The pathogenesis of Chlamydia pneumoniae-type pneumonitis in mice.

OBJECTIVE: To evaluate mice as experimental animals for Chlamydia pneumoniae (C. pneumoniae) infection and investigate the pathogenesis of C. pneumoniae derived pneumonitis. METHODS: Icr mice were inoculated with the C. pneumoniae strain, CWL-029, either intranasally or intravenously. After a single dose inoculation, mice were killed on the 1st, 3rd, 7th, 14th, 21st, 28th and 60th days. The pathological changes in lung tissue were analyzed. RESULTS: The Icr mice were shown to be susceptible to C. pneumoniae. Inoculation into mice with C. pneumoniae induced a prolonged course of lung infection, as demonstrated by persistence of lung pathology (up to 60 days). Via intranasal inoculation of mice, lung pathology was characterized by patchy interstitial pneumonitis with predominantly neutrophil leukocyte infiltration early (within the first 7 days) and lymphocyte infiltration in the later stages (14 days later) of infection. After intravenous inoculation, a similarly developed interstitial pneumonitis was observed, but it was milder and patchier, especially in early stages. C. pneumoniae DNA was detected by polymerase chain reaction (PCR) intermittently in the lung tissue. Inoculated mice developed serum IgG antibody responses. CONCLUSION: The Icr mice were susceptible to C. pneumoniae, resulting in a pulmonary infection characterized by interstitial pneumonitis, occurring most strongly via intranasal inoculation.

Animals↗
PubMed2003

Induction of type II alveolar epithelial cells apoptosis in mouse by lipopolysaccharide does not require TNF-alpha.

OBJECTIVE: To examine whether lipopolysaccharide (LPS)-induced apoptosis correlates with TNF-alpha release by type II alveolar epithelial cells (AEC II), whether TNF-alpha knockout (TNF KO) abrogates the induction of apoptosis by LPS and whether TNF-alpha is sufficient to induce apoptosis in this cell type. METHODS: AEC II were isolated from wild type mice and TNF KO mice. Cells were stimulated with LPS or recombinant murine TNF-alpha for 24 h. TNF-alpha in culture supernatant was determined by ELISA following LPS stimulation. Apoptosis was determined by the terminal deoxynucleotidyl transferase end-labeling (TUNEL) assay after treatment with either LPS or TNF-alpha. RESULTS: LPS induced apoptosis in wild type AEC II in a concentration-dependent manner. LPS-induced AEC II apoptosis was accompanied by an 11-fold increase (from 0.073 +/- 0.065 ng/ml in control to 0.94 +/- 0.14 ng/ml in 50 micro g/ml of LPS, P < 0.01) in TNF-alpha release. However, increasing concentrations (5 or 25 ng/ml) of recombinant murine TNF-alpha failed to induce AEC II apoptosis. In addition, apoptosis did occur in AEC II isolated from TNF KO mice following LPS stimulation. CONCLUSIONS: This study confirms that LPS induces TNF-alpha release and apoptosis in murine AEC II in vitro. Exogenous TNF-alpha failed to induce AEC II apoptosis, and apoptosis occurred following LPS stimulation in cells lacking the ability to produce TNF-alpha. Taken together, these results suggest that LPS-induced AEC II apoptosis occurs by a TNF-alpha-independent mechanism.

Animals↗
PubMed2003

[Effects of ultraviolet-C irradiation on membrane lipid peroxidation and activity of PS II electron transport in chloroplasts of Taxus cuspidata needles].

The isolated chloroplasts of Taxus cuspidata needles treated with 12 W.m-2 of ultraviolet-C (UV-C, 254 nm) irradiation were studied under laboratory conditions. The results showed that with the increase of UV-C irradiation, the carotenoids (Car) and glutathione (GSH) contents and superoxide dismutase (SOD) activity were decreased, while the malondialdehyde content (MDA) and the relative permeability of chloroplasts membrane were increased to various extents. The PS II electron transport activity was conspicuous decreased, which had a significant inverse ratio with photosynthetically active radiation (PAR). UV-C irradiation was insensitive on chlorophyll. The results indicated that membrane lipid peroxidation of chloroplasts caused by UV-C radiation was the reason of the decrease of PS II electron transport activity.

Chloroplasts↗
PubMed2003

[CH4 and N2O emissions from phaeozem rice field and their mitigative measures].

Determinations on the CH4 and N2O emissions from phaeozem rice field showed that their emission amount in rice growing season was much lower than any other regions in China. There was trade-off relationship between CH4 and N2O emissions(r = -0.513, P < 0.05). Under the same fertilization, compared with continual irrigation, intermittent irrigation could reduce significantly CH4 emission and increase N2O emission, but the overall warming potential of greenhouse effect was reduced greatly, while rice yield was not affected. Therefore, intermittent irrigation was an effective irrigation measures to reduce greenhouse gas emissions from rice field. In addition, investigations on CH4 and N2O emissions and their related microbial process showed a positive relation between methanogens number and CH4 emission(R2 = 0.82, P < 0.05), and the important relationship between the numbers of nitrifiers and denitrifiers and N2O emissions.

Biodegradation, Environmental↗
PubMed2003

[Effect of doubled CO2 and O3 concentration and their interactions on ultrastructure of soybean chloroplast].

The effect of doubled CO2 and O3 concentration on the ultrastructure of chloroplast in leaf cells of soybean was tested by open-top chamber method, and examined under transmission electron microscope. The results showed that under doubled CO2 concentration, the amount and volume of starch grains in chloroplast increased, but the chloroplast membrane and the lamellar structure still kept integrated. The accumulation of starch grains was restrained, and the chloroplast membrane and the lamellar structure were disorganized under doubled-O3 concentration. The ultrastructure of chloroplast was destroyed in different degrees under the interaction of doubled CO2 and O3 concentration. The damage to chloroplast arose from the abrupt doubling of CO2 and O3 was more severe than that from gradual increase of CO2 and O3 concentration. The negative effect of O3 was partly compensated by the positive effect of doubled CO2.

Carbon Dioxide↗
PubMed2003

[Methane oxidation in soil profiles of broad-leaved Korean pine mixed forest in Changbai Mountain].

Samples were collected from dark-brown forest soil in different depths in the virgin broad-leaved/Korean pine mixed forest in Changbai Mountain. Laboratory study on methane oxidation of forest soil revealed the vertical profiles of methane oxidation activity. The maximum methane oxidation occurred at the horizon 5-15 cm below the soil surface. When incubated with 400 ppmv methane, it had the highest uptake rate of 3.3 nmol.h-1.g-1 dw. Soil at horizon below 25 cm had a negligible capacity to oxidize methane. The methane-oxidation capacity of surface soil (0-5 cm) decreased because of the inhibition effect of high concentration NH4+ on methanotrophs.

Methane↗
PubMed2003

[Relationship between CH4 and N2O emissions and related microorganism populations in paddy soils under different water management regimes].

Methanogens, methanotrophs, nitrifiers and denitrifiers are the important microorganisms in the production and consumption of CH4 and N2O in soil. In order to understand the microbial processes related to the two greenhouse gases in paddy soil, the four bacteria groups in phaeozem (Hailun) and burozem (Shenyang) were surveyed during rice growth season by using MPN counting technique. The CH4 and N2O emissions were measured with closed chamber method. Two different water management regimes, i.e., continual irrigation and intermittent irrigation, were used for the two paddy soils. The results of multiple regression analysis showed that there was a significantly positive correlation between CH4 emission and methanogen population in both phaeozem and burozem under two water management regimes. In the soil of Shenyang, there was a significantly positive correlation between CH4 emission and methanotropli population. The N2O emission was significantly correlated to the denitrifier population in both phaeozem and burozem under intermittent irrigation, and in the soil of Shenyang, there was a significantly positive correlation between N2O emission and nitrifier population under two water managements.

Methane↗
PubMed2003

[Seasonal variations of soil microbial biomass, respiration rate and CH4 emission in black earth rice fields].

The measurements of soil microbial biomass C, respiration rate and CH4 emissions during one rice growth period in black earth rice fields showed that the soil microbial biomass C and respiration rate were depressed significantly by the application of slow-releasing urea at the early stage of rice growth period (P < 0.05), but almost not affected by intermittent irrigation. The CH4 emission was decreased by 32.5% in the intermittent irrigation treatments, but not significantly affected by the application of slow-releasing urea, compared to the control. It was significantly related to soil microbial biomass C in slow-releasing urea treatments.

Biomass↗
PubMed2003

[Effect of atmospheric CO2 enrichment on soil microbes and related factors].

This paper summarized the effects of atmospheric CO2 enrichment on soil microbes and their related factors, including soil microflora, soil respiration, soil microbial biomass, and higher plant-microbe symbiosis. The factors related to soil microbic activity such as litter decomposition, root exudates, soil nutrient availability, nutrient use efficiency and soil fauna were also affected by the CO2 enrichment.

Air↗
PubMed2002

Phase synchronization and its cluster feature in two-dimensional coupled map lattices.

Due to a diffusive nearest-neighbor coupling, phase-synchronized states can emerge in two-dimensional chaotic coupled map lattices. By defining a direction phase (like a spin with up or down direction) as the direction of two sequential iterations of the logistic map, we find several novel kinds of phase synchronization which correspond to four different regions in a phase diagram. For the phase with partial phase synchronization, as the coupling strength epsilon increases to a critical threshold epsilon(c), a percolationlike transition is found in the cluster feature of the direction phases relating to the pattern formation. In addition, a scaling of the percolation probability rho approximately (epsilon-epsilon(c))(beta) with beta=2.1 is obtained. The spatial and time correlation functions of the phase clusters are also discussed.

Journal Article↗
PubMed2002

Novel sintering behavior of polystyrene nanolatex particles in the filming process.

The filming process of polystyrene nanolatex (NPS) particles was studied by a combination of various methods. For a constant annealing time of 1 h, the AFM images showed that the deformation and interdiffusion temperatures of NPS particles were ca. 90 and 100-110 degrees C, respectively. In spin-lattice relaxation measurements of solid state NMR, it is found that T1L, T1S, and PL increased significantly after annealing at 90 and 100 degrees C for 1 h. DSC results showed that there was a exothermic peak near Tg after annealing for 1 h at the elected temperatures below 95 degrees C; otherwise, the exothermic peak disappeared after annealing at 100 degrees C or above. The apparent density of NPS increased suddenly in the temperature range of 90-110 degrees C. The results indicated that the macromolecules are highly constrained in NPS particles, leading to higher conformational energy, with more free volume and segments less restricted, which are the driving forces for the particles sintering at a lower temperature compared to the micro-PS particles with larger diameter.

Journal Article↗