P2X7 receptor inhibition prevents atrial fibrillation in rodent models of depression.

AIMS: Depression, the most prevalent psychiatric disorder, is associated with the occurrence and development of atrial fibrillation (AF). P2X7 receptor (P2X7R) activation participates in the development of depression, but little attention has been given to its role in AF. This study was to investigate the effects of P2X7R on AF in depression models. METHODS AND RESULTS: Lipopolysaccharide (LPS) and chronic unpredictable stress (CUS) were carried out to induce depression in rodents. Behavioural assessments, atrial electrophysiological parameters, electrocardiogram (ECG) parameters, western blot, and histology were performed. Atrial fibrillation inducibility was increased in both LPS- and CUS-induced depression, along with the up-regulation of P2X7R in atria. CUS facilitated atrial fibrosis. CUS reduced heart rate variability (HRV) and increased the expression of TH and GAP43, representing autonomic dysfunction. Down-regulation of Nav1.5, Cav1.2, Kv1.5, Kv4.3, Cx40, and Cx43 in CUS indicated the abnormalities in ion channels. In addition, the expression levels of TLR4, P65, P-P65, NLRP3, ASC, caspase-1, and IL-1ß were elevated in depression models. Pharmacological inhibitor (Brilliant Blue G, BBG) or genetic deficiency of P2X7R significantly mitigated depressive-like behaviours; ameliorated electrophysiological deterioration and autonomic dysfunction; improved ion channel expression and atrial fibrosis; and prevented atrial NLRP3 inflammasome activation in the pathophysiological process of AF in depression models. CONCLUSION: LPS or CUS induces AF and promotes P2X7R-dependent activation of NLRP3 inflammasome, whereas pharmacological P2X7R inhibition or P2X7R genetic deficiency prevents atrial remodelling without interrupting normal atrial physiological functions. Our results point to P2X7R as an important factor in the pathology of AF in depression.

Kinetic characteristics of and critical stages for mercury accumulation in rice (Oryza sativa L.).

By studying the dynamic characteristics of and key growth stages for mercury (Hg) enrichment in rice, the Hg migration and translocation processes in this species can be better understood. In this study, a pot experiment was conducted, wherein two rice cultivars, Tianyouhuazhan (TYHZ, indica) and Zhendao 18 (ZD18, japonica), were selected and planted for analysing the Hg accumulation kinetic characteristics in rice plants. The plants were sampled at each growth stage, and the biomass and total Hg (THg) and methylmercury (MeHg) concentrations of each tissue were measured. The relative Hg contribution rates (CRs) in whole rice plants and rice grains were calculated, and the growth stage with the highest relative contribution was identified as the key growth stage for Hg accumulation. The results indicated that in rice, the MeHg translocation capability was stronger than the THg translocation capability. Significant differences in the kinetic characteristics of Hg accumulation were found between the two rice cultivars, and the TYHZ rice grains had a stronger Hg accumulation ability than the ZD18 rice grains. The key growth stages for THg accumulation in whole rice plants of both cultivars were the tillering and booting stages, while that for MeHg accumulation was the tillering stage. The key period for Hg accumulation in rice grains was the grain filling stage for both cultivars. The insights from this study could provide scientific guidance for the safe production of rice in Hg-contaminated soil.

Controlling Factors and Predictive Models of Total Mercury and Methylmercury Accumulation in Rice (Oryza sativa L.) from Mercury-Contaminated Paddy Soils.

It is urgent to detect the major controlling factors and establish predictive models of mercury (Hg) accumulation in rice. A pot trial was conducted, exogenous Hg was added to 19 paddy soils at 4 concentration levels in this study. The major controlling factors of total Hg (THg) in brown rice were soil THg, pH and organic matter (OM) content, while those of methylmercury (MeHg) in brown rice were soil MeHg and OM. THg and MeHg in brown rice could be well predicted by soil THg, pH and clay content. The data from previous studies were collected to validate the predictive models of Hg in brown rice. The predicted values of Hg in brown rice were within the twofold prediction intervals of the observations, which demonstrated the predictive models in this study were reliable. The results could provide theoretical foundation for the risk assessment of Hg in paddy soils.

Double-edged effects of elevating temperature on the aging of exogenous arsenic in flooded paddy soils.

Temperature variation can have a significant impact on arsenic (As) bioavailability in paddy soils. However, details regarding the transformation of exogenous As during the aging process in paddy soils at various temperatures remain unclear. This work investigated the effects of temperature on the As extractability and As species transformation of three paddy soils spiked with exogenous arsenate at 60 mg kg-1 under flooded aging and explored the related chemical and microbial mechanisms. The results showed that 0.05 M NH4H2PO4-extractable As decreased over time during flooded aging for 192 days, and it decreased by approximately one-third at 35 °C compared with 15 °C and 25 °C at the same aging time, indicating that higher temperatures facilitated the decrease in As extractability. As(V) reduction mainly occurred at 35 °C because the abundance and As(V)-reducing capacity of the predominant indigenous bacteria, the Bacillus sp strains, and the abundance of the arrA gene were significantly higher than those at 15 °C and 25 °C. The reduction of As(V) to As(III) and aging occurred simultaneously. The kinetic models were established, and the rate constants of the reduction and aging processes were obtained. Soil properties significantly affected the aging and reduction processes of extractable As(V). Our study indicated that elevating temperature had dual effects on the environmental risk of As in the flooded aging process. The previous definition of "aging" based on cationic metals needs to be updated according to the transformation characteristics of As species in flooded conditions. Our results addressed the necessity of impeding the reduction of As(V) in paddy soils under global warming.

Fluorescent-Raman Binary Star Ratio Probe for MicroRNA Detection and Imaging in Living Cells.

The expression of microRNAs (miRNAs) is critical in gene regulation and has been counted into disease diagnosis marks. Precise imaging and quantification of miRNAs could afford the important information for clinical diagnosis. Here, two smart binary star ratio (BSR) probes were designed and constructed, and miRNA triggered the connection of the binary star probes and the reciprocal changes of dual signals in living cells. This multifunctional probe integrates fluorescence and surface enhanced Raman scattering (SERS) imaging, with enzyme-free numerator signal amplification for dual-mode imaging and dual-signal quantitative analysis of miRNA. First, compared with the single-mode ratio imaging method, using fluorescence-SERS complementary ratio imaging, this probe enables more accurate imaging contrast for direct visualization signal changes in living cells. Multiscale information about the dynamic behavior of miRNA and the probe is acquired. Next, via SERS reverse signal ratio response and a novel enzyme-free numerator signal amplification, the amplified signal and reduced black value were achieved in the quantification of miRNA. More importantly, BSR probes showed good stability in cells and were successfully used for accurate tracing and quantification of miR-203 from MCF-7 cells. Therefore, the reported BSR probe is a potential tool for the reliable monitoring of biomolecule dynamics in living cells.

Volatile-mediated antagonism of soil bacterial communities against fungi.

Competition is a major type of interaction between fungi and bacteria in soil and is also an important factor in suppression of plant diseases caused by soil-borne fungal pathogens. There is increasing attention for the possible role of volatiles in competitive interactions between bacteria and fungi. However, knowledge on the actual role of bacterial volatiles in interactions with fungi within soil microbial communities is lacking. Here, we examined colonization of sterile agricultural soils by fungi and bacteria from non-sterile soil inoculums during exposure to volatiles emitted by soil-derived bacterial communities. We found that colonization of soil by fungi was negatively affected by exposure to volatiles emitted by bacterial communities whereas that of bacteria was barely changed. Furthermore, there were strong effects of bacterial community volatiles on the assembly of fungal soil colonizers. Identification of volatile composition produced by bacterial communities revealed several compounds with known fungistatic activity. Our results are the first to reveal a collective volatile-mediated antagonism of soil bacteria against fungi. Given the better exploration abilities of filamentous fungi in unsaturated soils, this may be an important strategy for bacteria to defend occupied nutrient patches against invading fungi. Another implication of our research is that bacterial volatiles in soil atmospheres can have a major contribution to soil fungistasis.

RNA-binding protein SFPQ cooperates with HDAC1 to suppress CD40 transcription in pulmonary adventitial fibroblasts.

Pulmonary artery adventitial fibroblasts, the most abundant cellular constituent of adventitia, are often the first to be activated and reprogrammed to then influence the tone and structure of the vessel wall in pulmonary arterial hypertension (PAH). Our previous study found that interruption of CD40 ligand (CD40L)-CD40 signaling improves the efficacy of transplanted endothelial progenitor cells in monocrotaline induced-PAH. However, whether CD40L-CD40 signaling is involved in the activation of adventitial fibroblasts in PAH and whether Drosophila behavior human splicing (DBHS) protein family members have any roles during adventitial fibroblasts activation are completely unclear. Here, we show that soluble CD40L (sCD40L) stimulation progressively increases pro-inflammatory activity, proliferation, and migration of pulmonary adventitial fibroblasts. Besides, sCD40L stimulation decreases splicing factor proline- and glutamine-rich protein (SFPQ) protein (one member of DBHS protein family) expression, while SFPQ overexpression suppresses sCD40L stimulation-induced proliferation and migration of pulmonary adventitial fibroblasts by repressing CD40 transcription. Moreover, ChIP assays found that sCD40L stimulation promotes histone H3 tri-methylation at lysine 4 (H3K4me3), H3K36me3, and H3K27 acetylation (H3K27ac) modifications on CD40 promoter region in pulmonary adventitial fibroblasts, while SFPQ overexpression decreases H3K36me3 modification and increases H3K36ac on CD40 promoter region by interacting with histone deacetylase-1 (HDAC1) to inhibit CD40 transcription. This in-depth study shows that CD40L-CD40 signaling promotes activation of pulmonary adventitial fibroblasts by increasing proliferation, migration, and pro-inflammatory activity of adventitial fibroblasts, and SFPQ could inhibit CD40 transcription though switching H3K36me3 to H3K36ac modifications on its promoter by interacting with HDAC1. This study, first, uncovers the roles of SFPQ on CD40L-CD40 signaling-mediated activation of pulmonary adventitial fibroblasts.

Downregulation of Cypher induces apoptosis in cardiomyocytes via Akt/p38 MAPK signaling pathway.

Background: Dilated cardiomyopathy (DCM) is considered as the most common form of non-ischemic cardiomyopathy with a high mortality worldwide. Cytoskeleton protein Cypher plays an important role in maintaining cardiac function. Genetic studies in human and animal models revealed that Cypher is involved in the development of DCM. However, the underlying molecular mechanism is not fully understood. Accumulating evidences suggest that apoptosis in myocytes may contribute to DCM. Thus, the purpose of this study is to define whether lack of Cypher in cardiomyocytes can elevate apoptosis signaling and lead to DCM eventually. Methods and Results: Cypher-siRNA sufficiently inhibited Cypher expression in cardiomyocytes. TUNEL-positive cardiomyocytes were increased in both Cypher knockdown neonatal rat cardiomyocytes and Cypher knockout mice hearts, which were rare in the control group. Flow cytometry further confirmed that downregulation of Cypher significantly increased myocytes apoptosis in vitro. Cell counting kit-8 assay revealed that Cypher knockdown in H9c2 cells significantly reduced cell viability. Cypher knockdown was found to increase cleaved caspase-3 expression and suppress p21, ratio of bcl-2 to Bax. Cypher-deficiency induced apoptosis was linked to downregulation of Akt activation and elevated p-p38 MAPK accumulation. Pharmacological activation of Akt with SC79 attenuated apoptosis with enhanced phosphorylation of Akt and reduced p-p38 MAPK and Bax expression. Conclusions: Downregulation of Cypher participates in the promotion of cardiomyocytes apoptosis through inhibiting Akt dependent pathway and enhancing p38 MAPK phosphorylation. These findings may provide a new potential therapeutic strategy for the treatment of DCM.

Assessment of the immobilization effectiveness of several amendments on a cadmium-contaminated soil using Eisenia fetida.

Proper protocols for assessing the remediation effectiveness of contaminated soils are an important part of remediation projects. In the present study, the residual immobilization effectiveness of hydrated lime (L), hydroxyapatite (H), biochar (B) and organic fertilizer (F) alone and in combination was assessed by Eisenia fetida. The results showed that the application of amendments had no significant effect on the death rate and average fresh weight loss of earthworms. The earthworm Cd concentration increased with prolonged exposure time, however, the significant immobilization efficacy of amendments observed on the 7th day nearly disappeared after 28 days of exposure. The immobilization efficiencies, estimated by the earthworms internal Cd concentration, of L, H and B on the 7th day were 38.6%, 37.8% and 20.7%, respectively. These values decreased to 4.9%, 19.8% and 15.1%, respectively, on the 28th day. The detoxification effect of amendments was confirmed by the Cd subcellular fractionation in earthworms with lower proportions of Cd distributed in the metal-sensitive fractions in L, H and B treatments. The level of oxidative stress response of earthworms increased with exposure duration and amendments alleviated the oxidative damage induced by Cd to the earthworms. In addition, the pH and CaCl2-Cd in soils were both increased due to earthworm life activities and gut-related ingestion. In summary, the assessment of immobilization effectiveness of heavy metal-contaminated soils using Eisenia fetida was time-dependent. The immobilization efficacy of L and H performed better than B and F on the 7th day, while H and B performed better than L and F on the 28th day. Accordingly, the short-term earthworm exposure experiment (7 days) was recommended to be an alternative approach to time-consuming plant bioassays in assessment of reduced phytoavailability in chemical immobilization remediation. But the impact of earthworms on the immobilization effect of amendments needs to be considered in practical remediation.

A tillering application of zinc fertilizer based on basal stabilization reduces Cd accumulation in rice (Oryza sativa L.).

Cadmium (Cd) contamination in paddy fields has received extensive attention throughout the world, especially in China. In this study, treatments of a lime application with or without zinc sulfate as basal fertilizer, a basal or tillering application of zinc sulfate, and basal stabilization using lime combined with a tillering application of zinc sulfate were designed in a field trial to investigate their contributions to the uptake and translocation of Cd in rice plants. The results showed that basal stabilization using lime significantly decreased brown rice Cd by 42%; the CaCl2-extractable Cd in the soil was decreased by 46-51%, but the phytoavailability of Zn in the soil was also inhibited. The basal or tillering application of zinc sulfate significantly inhibited the upward transport of Cd (from the root to the shoot) while having no significant impact on CaCl2-extractable Cd; consequently, the concentration of Cd in the brown rice was reduced by only 17-25%. Compared with the lime application alone, the basal application of lime together with zinc sulfate did not further reduce the Cd in brown rice. However, basal stabilization using lime combined with the tillering application of zinc decreased the Cd in brown rice by 73%, which was attributed to the reduced CaCl2-extractable Cd and the competitive effect of Zn on Cd, in which the inhibition of the upward transport of Cd inside the root played an important role. Two field verification tests conducted during the next year also demonstrated that this combined method significantly decreased the level of Cd in brown rice.

Phomopsis liquidambari colonization promotes continuous cropping peanut growth by improving the rhizosphere microenvironment, nutrient uptake and disease incidence.

BACKGROUND: The continuous cropping of peanuts is a primary cause of yield and quality loss. Solutions to this problem should be therefore developed to ensure the sustainability of peanut production. RESULTS: In this study, colonization by the endophytic fungus Phomopsis liquidambari was detected, which led to significantly improved rhizosphere soil microenvironment, enhanced N, P and K assimilation and suppressed incidence of peanut disease. Statistical analysis demonstrated that the yield enhancement was significantly correlated with improvement of the rhizosphere soil microenvironment and the peanut's physiological status by P. liquidambari colonization. In addition, P. liquidambari colonization also significantly improved peanut quality. CONCLUSION: Our results indicate that the practical application of the endophytic fungus P. liquidambari has a strong potential to alleviate the obstacles associated with continuous peanut cropping under field conditions. © 2018 Society of Chemical Industry.

Effects of combined amendments on crop yield and cadmium uptake in two cadmium contaminated soils under rice-wheat rotation.

Soil cadmium (Cd) contamination in China has become a serious concern due to its high toxicity to human health through food chains. A pot experiment was conducted to investigate the effects of hydrated lime (L), hydroxyapatite (H) and organic fertilizer (F) alone or in combination to remedy a mild (DY) and a moderate (YX) Cd contaminated agricultural soil under rice-wheat rotation. Results showed that crops grain yield and Cd concentration, soil pH, CaCl2 extractable Cd and Cd speciation were markedly affected by the amendments. In both cropping seasons, hydrated lime and hydroxyapatite significantly immobilized soil Cd, and hydroxyapatite, organic fertilizer significantly increased grain yield. Hydrated lime mainly increased soil carbonates bound Cd fractions resulted from 16.7% to 36.2% and from 16.8% to 28.3%, and hydroxyapatite increased Fe/Mn oxides Cd fractions from 19.3% to 33.4% and from 31.4% to 42.1% in the DY and YX soils, respectively; while organic fertilizer slightly increased soil exchangeable and organic matter bound Cd fractions. Besides, combined amendments contain alkaline materials and organic materials have the potential to decrease grain Cd and increase grain yield simultaneously. Therefore, in view of the effects of amendments on grain yield and Cd concentration, the cost as well as the potential benefits expected, combined amendments like hydrated lime + organic fertilizer, hydrated lime + hydroxyapatite + organic fertilizer are recommended in practical application. Mechanisms of Cd immobilization affected by amendments are mainly attributed to the changes in soil Cd availability and crops root uptake rather than internal translocation in plants.

Stability of immobilization remediation of several amendments on cadmium contaminated soils as affected by simulated soil acidification.

Chemical immobilization is a practical approach to remediate heavy metal contamination in agricultural soils. However, the potential remobilization risks of immobilized metals are a major environmental concern, especially in acid rain zones. In the present study, changes in the immobilization efficiency of several amendments as affected by simulated soil acidification were investigated to evaluate the immobilization remediation stability of several amendments on two cadmium (Cd) contaminated soils. Amendments (hydrated lime, hydroxyapatite and biochar) effectively immobilized Cd, except for organic fertilizer, and their immobilizations were strongly decreased by the simulated soil acidification. The ratio of changes in CaCl2-extractable Cd: pH (△CaCl2-Cd/△pH) can represent the Cd remobilization risk of different amended soils. Hydroxyapatite and biochar had a stronger durable immobilizing effect than did hydrated lime, particularly in soil with a lower pH buffering capacity, which was further confirmed by the Cd concentration and accumulation in lettuce. These results can be attributed to that hydroxyapatite and biochar transformed greater proportions of exchangeable Cd to other more stable fractions than lime. After 48 weeks of incubation, in soil with a lower pH buffering capacity, the immobilization efficiencies of lime, hydroxyapatite, biochar and organic fertilizer in the deionized water group (pH 6.5) were 71.7%, 52.7%, 38.6% and 23.9%, respectively, and changed to 19.1%, 33.6%, 26.5% and 5.0%, respectively, in the simulated acid rain group (pH 2.5). The present study provides a simple method to preliminarily estimate the immobilization efficiency of amendments and predict their stability in acid rain regions before large-scale field application. In addition, hydrated lime is recommended to be combined with other acid-stable amendments (such as hydroxyapatite or biochar) to remediate heavy metal-contaminated agricultural soils in acid precipitation zones.

Tanshinone II A Attenuates TNF-α-Induced Expression of VCAM-1 and ICAM-1 in Endothelial Progenitor Cells by Blocking Activation of NF-κB.

BACKGROUND/AIMS: Tanshinone IIA (Tan IIA) is effective in the treatment of inflammation and atherosclerosis. The adhesion of inflammatory cells to vascular endothelium plays important role in atherogenic processes. This study examined the effects of Tan IIA on expression of adhesion molecules in tumor necrosis factor-α (TNF-α)-induced endothelial progenitor cells (EPCs). METHODS: EPCs were pretreated with Tan IIA and stimulated with TNF-α. Mononuclear cell (MNC) adhesion assay was performed to assess the effects of Tan IIA on TNF-α-induced MNC adhesion. Expression of vascular cell adhesion molecule-1 (VCAM-1)/intracellular adhesion molecule-1 (ICAM-1) and activation of Nuclear factor κB (NF-κB) signaling pathway were measured. RESULTS: The results showed that the adhesion of MNCs to TNF-α-induced EPCs and expression of VCAM-1/ICAM-1 in EPCs were promoted by TNF-α, which were reduced by Tan IIA. TNF-α increased the amount of phosphorylation of NF-κB, IκB-α and IKKα/ß in cytosolic fractions and NF-κB p65 in nucleus, while Tan IIA reduced its amount. CONCLUSION: This study demonstrated a novel mechanism for the anti-inflammatory/anti-atherosclerotic activity of Tan IIA, which may involve down-regulation of VCAM-1 and ICAM-1 through partial blockage of TNF-α-induced NF-κB activation and IκB-α phosphorylation by the inhibition of IKKα/ß pathway in EPCs.

Interruption of CD40 Pathway Improves Efficacy of Transplanted Endothelial Progenitor Cells in Monocrotaline Induced Pulmonary Arterial Hypertension.

BACKGROUND/AIMS: Transplantation of endothelial progenitor cells (EPCs) plays a therapeutic role in pulmonary arterial hypertension (PAH). Meanwhile, recruitment of progenitors has potential inflammatory effects and exaggerates vascular injury. CD40 pathway is identified as a major player in vascular inflammatory events. In this study, we investigated the role of CD40 pathway in regulating early outgrowth EPC functions, and searched for improvements in PAH cell therapy. METHODS: EPCs were isolated from rat bone marrow and cultured for 7 days. After treatment with soluble CD40 ligand (sCD40L) for 24 hours, EPC migration, adhesion, proliferation, paracrine and vasculogenesis functions were tested. Rat PAH model was founded by subcutaneous injection of monocrotaline (MCT). Control EPCs or lentivirus vectors (Lv)-shRNA-CD40 EPCs were infused via tail vein at day 7, 14, and 21 after MCT injection. Therapeutic effects were evaluated at day 28. RESULTS: sCD40L dose-dependently impaired EPC migration, adhesion, proliferation, and vasculogenesis functions. However, paracrine effects of soluble intercellular adhesion molecule-1, vascular endothelial growth factor and interleukin-6 were dose-dependently improved by sCD40L. Control EPC-derived conditioned medium protected endothelial cell in vitro vasculogenesis, while sCD40L-pretreated ones showed detrimental effects. After MCT injection, sCD40L levels in rat serum increased gradually. Other than in vitro results, benefits of both two EPC treatments were obvious, even taken at day 21. Benefits of control EPCs wore off over time, but those of Lv-shRNA-CD40 EPCs were more effective and enduring, as characterized by both ameliorated rat hemodynamic and reversed vascular remodeling. Furthermore, Lv-shRNA-CD40 EPCs integrated into endothelium better, rather than into adventitia and media. CONCLUSION: sCD40L impaired protective effects of EPCs. Traditional EPC treatments were limited in PAH, while interruption of CD40 pathway of transplanted cells could apparently improve the therapeutic efficacy.

Heavy metals in navel orange orchards of Xinfeng County and their transfer from soils to navel oranges.

This study investigated heavy metal concentrations in soils and navel oranges of Xinfeng County, a well-known navel orange producing area of China. The results showed that the average concentrations of lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As) and mercury (Hg) in orchard soils all increased compared to the regional background values, especially for Cd, which increased by 422%. When compared to the Chinese Environmental Quality Standard for soil (GB15618-1995), Pb, Cr and Hg concentrations in all orchard soil samples were below the limit standards, but Cd concentrations in 24 soil samples (21%) and As concentrations in 8 soil samples (7%) exceeded the limit standards. However, concentrations of all heavy metals in navel orange pulps were within the National Food Safety Standard of China (GB 2762-2012). Dietary risk assessment also showed that the exposure to these five heavy metals by consumption of navel oranges could hardly pose adverse health effects on adults and children. Since the range and degree of soil Cd pollution was widest and the most severe of all, Cd was taken as an example to reveal the transfer characteristics of heavy metals in soil-navel orange system. Cd concentrations in different organs of navel orange trees decreased in the following order: root>leaf>peel>pulp. That navel oranges planted in the Cd contaminated soils were within the national food safety standard was mainly due to the low transfer factor for Cd from soil to pulp (TFpulp). Further studies showed that TFpulp was significantly negatively correlated with soil pH, organic carbon (OC) and cation exchange capacity (CEC). Based on these soil properties, a prediction equation for TFpulp was established, which indicated that the risk for Cd concentration of navel orange pulp exceeding the national food limit is generally low, when soil Cd concentration is below 7.30 mg/kg. If appropriate actions are taken to increase soil pH, OC and CEC, Cd concentrations in navel orange pulps could be further reduced.

Activation of extracellular signal-regulated kinase 1/2 and Sp1 may contribute to the expression of tissue inhibitor of metalloproteinases-1 induced by transforming growth factor-ß1 in human pulmonary arterial smooth muscle cells.

BACKGROUND AIMS: Tissue inhibitor of metalloproteinases-1 (TIMP-1) plays an important role in the development of pulmonary arterial hypertension. However, the molecular regulatory mechanisms of TIMP-1 in the pulmonary arteries are not fully understood, especially in human pulmonary arterial smooth muscle cells (HPASMCs). We investigated the signaling pathway involved in the regulation of TIMP-1 in HPASMCs induced by transforming growth factor (TGF)-ß1. METHODS: Cultured HPASMCs were incubated with different concentrations of TGF-ß1 (0-40 ng/mL) for 24 h or with 10 ng/mL TGF-ß1 for different times (1-48 h). RESULTS: Western blot, real-time polymerase chain reaction and enzyme-linked immunosorbent assay analyses showed that TGF-ß1 enhanced the expression and secretion of TIMP-1 in a time-dependent and dose-dependent fashion. TGF-ß1 could phosphorylate two of the three mitogen-activated protein kinases-extracellular signal-regulated kinase 1/2 (ERK1/2) and p38, but not c-Jun NH2-terminal kinase. Of these kinases, only the inhibition of ERK1/2 by U0126, which was a specific inhibitor of mitogen-activated protein kinase/ERK1/2, effectively blocked the TGF-ß1-induced expression of TIMP-1. Mithramycin, an inhibitor of Sp1 transcription factor, also significantly inhibited the expression of TIMP-1. Additionally, electrophoretic mobility shift assay showed that TGF-ß1 could up-regulate the DNA-binding activity of Sp1 and that U0126 and mithramycin could effectively inhibit these events. CONCLUSIONS: TGF-ß1 could stimulate the expression and secretion of TIMP-1 in HPASMCs in a time-dependent and dose-dependent fashion, and ERK1/2 and Sp1 signaling pathways might be involved in these activities.

Phytotoxicity and accumulation of chromium in carrot plants and the derivation of soil thresholds for Chinese soils.

Soil environmental quality standards in respect of heavy metals for farmlands should be established considering both their effects on crop yield and their accumulation in the edible part. A greenhouse experiment was conducted to investigate the effects of chromium (Cr) on biomass production and Cr accumulation in carrot plants grown in a wide range of soils. The results revealed that carrot yield significantly decreased in 18 of the total 20 soils with Cr addition being the soil environmental quality standard of China. The Cr content of carrot grown in the five soils with pH>8.0 exceeded the maximum allowable level (0.5mgkg(-1)) according to the Chinese General Standard for Contaminants in Foods. The relationship between carrot Cr concentration and soil pH could be well fitted (R(2)=0.70, P<0.0001) by a linear-linear segmented regression model. The addition of Cr to soil influenced carrot yield firstly rather than the food quality. The major soil factors controlling Cr phytotoxicity and the prediction models were further identified and developed using path analysis and stepwise multiple linear regression analysis. Soil Cr thresholds for phytotoxicity meanwhile ensuring food safety were then derived on the condition of 10 percent yield reduction.