Background. Several types of drugs have been recommended for the secondary prevention of myocardial infarction (MI). However, these conventional strategies have several limitations, such as low adherence, high cost, and side effects during long time use. Novel approaches to this problem are still needed. This trial aimed to test the effectiveness and safety of Qi-Shen-Yi-Qi Dripping Pills (QSYQ), a multi-ingredient Chinese patent medicine, for the secondary prevention of MI. Methods and Findings. A total of 3505 eligible patients were randomly assigned to QSYQ group (1746 patients) or aspirin group (1759). Patients took their treatments for 12 months. The final follow-up visit took place 6 months after the end of the trial drugs. The 12-month and 18-month estimated incidences of the primary outcome were 2.98% and 3.67%, respectively, in the QSYQ group. The figures were 2.96% and 3.81% in the aspirin group. No significant difference was identified between the groups. Conclusions. This trial did not show significant difference of primary and secondary outcomes between aspirin and QSYQ in patients who have had an MI. Though inconclusive, the result suggests that QSYQ has similar effects to aspirin in the secondary prevention of MI.
The enzymatic hydrolysis step converting lignocellulosic materials into fermentable sugars is recognized as one of the major limiting steps in biomass-to-ethanol process due to the low efficiency of enzymes and their cost. Xylanases have been found to be important in the improvement of the hydrolysis of cellulose due to the close interaction of cellulose and xylan. In this work, the effects of carbohydrate-binding module (CBM family II) of the xylanase 11 from Nonomuraea flexuosa (Nf Xyn11) on the adsorption and hydrolytic efficiency toward isolated xylan and lignocellulosic materials were investigated.
The intact family 11 xylanase of N. flexuosa clearly adsorbed on wheat straw and lignin, following the Langmuir-type isotherm. The presence of the CBM in the xylanase increased the adsorption and hydrolytic efficiency on insoluble oat spelt xylan. But the presence of the CBM did not increase adsorption on pretreated wheat straw or isolated lignin. On the contrary, the CBM decreased the adsorption of the core protein to lignin containing substrates, indicating that the CBM of N. flexuosa xylanase did not contribute to the non-productive adsorption.
The CBM of the N. flexuosa xylanase was shown to be a xylan-binding module, which had low affinity on cellulose. The CBM of the N. flexuosa xylanase reduced the non-specific adsorption of the core protein to lignin and showed potential for improving the hydrolysis of lignocellulosic materials to platform sugars.
Carbohydrate binding module; Xylanase; Adsorption; Xylan
GTP cyclohydrolase 1 (GTPCH1) is the rate-limiting enzyme in de novo synthesis of tetrahydrobiopterin (BH4), an essential cofactor for endothelial nitric oxide synthase (eNOS) dictating at least partly, the balance of nitric oxide (NO) and superoxide (O2•−) produced by this enzyme. The aim of this study was to determine the effect of acute inhibition of GTPCH1 on BH4, eNOS function, and blood pressure in vivo. Exposure of bovine or mouse aortic endothelial cells to GTPCH1 inhibitors (DAHP or NAS) or GTPCH1- siRNA significantly reduced BH4 and NO levels, but increased superoxide (O2•−) levels. This increase was abolished by sepiapterin (BH4 precursor) or L-NAME (non-selective NOS inhibitor). Incubation of isolated murine aortas with DAHP or NAS impaired acetylcholine-induced endothelium-dependent relaxation, but not endothelium-independent relaxation. Aortas from GTPCH1 siRNA-injected mice, but not their control-siRNA injected counterparts, also exhibited impaired endothelium-dependent relaxation. BH4 reduction induced by GTPCH1 siRNA injection was associated with increased aortic levels of O2•−, 3-nitrotyrosine, and adhesion molecules (ICAM1 and VCAM1) as well as a significantly elevated systolic, diastolic, and mean blood pressure in C57BL6 mice. GTPCH1 siRNA was unable to elicit these effects in eNOS−/− mice. Sepiapterin supplementation, which had no effect on high blood pressure in eNOS−/− mice, partially reversed GTPCH1 siRNA-induced elevation of blood pressure in wild type mice. In conclusion, GTPCH1 via BH4 maintains normal blood pressure and endothelial function in vivo by preserving NO synthesis by eNOS.
Hypertension; Nitric Oxide; Superoxide Anions; Endothelial Nitric Oxide Synthase; Tetrahydrobiopterin; GTP-cyclohydrolase 1; Oxidative Stress
Species of the shore-fly genus Rhynchopsilopa Hendel from China are reviewed. Four new species (Rhynchopsilopa guangdongensis
sp. n., Rhynchopsilopa huangkengensis
sp. n., Rhynchopsilopa jinxiuensis
sp. n., Rhynchopsilopa shixingensis
sp. n.) and two previously known species, Rhynchopsilopa longicornis (Okada) and Rhynchopsilopa magnicornis Hendel, are described or redescribed. A key to the species hitherto known from China is presented.
Diptera; Ephydridae; Rhynchopsilopa; new species; China
Background PI3K/Akt signaling has been shown to be activated in a variety of cancers. However, the correlation between Akt activation and VEGF expression is unclear in colon cancer tissues. This study aimed to investigate the expression and predictive value of phosphorylated Akt (pAkt) and VEGF in colon cancer tissues. The expression of PI3K, pAkt and VEGF was detected by immunohistochemical staining in 60 samples of colon cancer tissues and their corresponding adjacent normal colon tissues. In addition, the correlations between the expression levels of the 3 proteins and the clinicopathological parameters of the colon cancer cases were analyzed. The positive rates of PI3K, pAkt and VEGF expression were 71.7% (43/60), 68.3% (41/60) and 61.7% (37/60) in colon cancer, respectively, which were significantly higher than in adjacent normal colon tissues (P<0.001). Correlation analyses showed that PI3K expression was not significantly associated with the gender or age of the patients, tumor size or differentiation (P>0.05), but was closely associated with serous coat infiltration and lymphatic metastasis of colon cancer (P<0.05). Neither pAkt nor VEGF expression were significantly associated with the gender or age of the patients, or tumor differentiation (P>0.05), but were closely associated with tumor size, serous coat infiltration and lymphatic metastasis of colon cancer (P<0.05). In addition, the expression levels of Pl3K and pAkt were positively correlated with that of VEGF in colon cancer tissues (P<0.05). Our data show a positive correlation between PI3K/Akt activation and VEGF expression in colon cancer tissues and indicate that pAkt is an independent prognostic marker for colon cancer patients.
colon cancer; PI3K/Akt; VEGF; angiogenesis; prognosis
Pheromone-binding proteins (PBPs) of the gypsy moth, Lymantria dispar L., play an important role in olfaction. Here structures of PBPs were first built by Homology Modeling, and each model of PBPs had seven α-helices and a large hydrophobic cavity including 25 residues for PBP1 and 30 residues for PBP2. Three potential semiochemicals were first screened by CDOCKER program based on the PBP models and chemical database. These chemicals were Palmitic acid n-butyl ester (Pal), Bis(3,4-epoxycyclohexylmethyl) adipate (Bis), L-trans-epoxysuccinyl-isoleucyl-proline methyl ester propylamide (CA-074). The analysis of chemicals docking the proteins showed one hydrogen bond was established between the residues Lys94 and (+)-Disparlure ((+)-D), and л-л interactions were present between Phe36 of PBP1 and (+)-D. The Lys94 of PBP1 formed two and three hydrogen bonds with Bis and CA-074, respectively. There was no residue of PBP2 interacting with these four chemicals except Bis forming one hydrogen bond with Lys121. After simulating the conformational changes of LdisPBPs at pH7.3 and 5.5 by constant pH molecular dynamics simulation in implicit solvent, the N-terminal sequences of PBPs was unfolded, only having five α-helices, and PBP2 had larger binding pocket at 7.3 than PBP1. To investigate the changes of α-helices at different pH, far-UV and near-UV circular dichroism showed PBPs consist of α-helices, and the tertiary structures of PBP1 and PBP2 were influenced at pH7.3 and 5.5. The fluorescence binding assay indicated that PBP1 and PBP2 have similarly binding affinity to (+)-D at pH 5.5 and 7.3, respectively. At pH 5.5, the dissociation constant of the complex between PBP1 and 2-decyl-1-oxaspiro [2.2] pentane (OXP1) was 0.68±0.01μM, for (+)-D was 5.32±0.11μM, while PBP2 with OXP1 and (+)-D were 1.88±0.02μM and 5.54±0.04μM, respectively. Three chemicals screened had higher affinity to PBP1 than (+)-D except Pal at pH5.5, and had lower affinity than (+)-D at pH7.3. To PBP2, these chemicals had lower affinity than the sex pheromone except Bis at pH 5.5 and pH 7.3. Only PBP1 had higher affinity with Sal than the sex pheromone at pH 5.5. Therefore, the structures of PBP1 and PBP2 had different changes at pH5.5 and 7.3, showing different affinity to chemicals. This study helps understanding the role of PBPs as well as in developing more efficient chemicals for pest control.
Lymantria dispar; pheromone-binding protein; bioinformatics; discrimination; semiochemicals
In the present study, we standardized a TaqMan locked nucleic acid (LNA) real-time polymerase chain reaction (PCR) probe for the accurate quantification and detection of hepatitis B virus (HBV) DNA in serum (plasma), and evaluated its methodology. LNA probe technology had a much better detection performance in HBV DNA than the common TaqMan probe. The assay based on the LNA probe had a wider linear detection range, higher sensitivity, stability and amplification efficiency, and a lower concentration of probes than the TaqMan probe. Among the 15 cases with chronic hepatitis B surface antigen (HBsAg) (+) alone, only 4 cases that were detected by TaqMan real-time PCR were negative; however, the same samples were positive by LNA real-time PCR (p<0.05). A positive correlation between viral load measurements for the 35 samples with HBV-positive DNA was detected in both LNA and TaqMan real-time PCR.
human hepatitis B virus; real-time polymerase chain reaction; probe; locked nucleic acid; TaqMan
Due to the complexity of lignocellulosic materials, a complete enzymatic hydrolysis into fermentable sugars requires a variety of cellulolytic and xylanolytic enzymes. Addition of xylanases has been shown to significantly improve the performance of cellulases and to increase cellulose hydrolysis by solubilizing xylans in lignocellulosic materials. The goal of this work was to investigate the effect of acetyl xylan esterase (AXE) originating from Trichoderma reesei on xylan solubilization and enzymatic hydrolysis of cellulose.
The solubilization of xylan in pretreated wheat straw and giant reed (Arundo donax) by xylanolytic enzymes and the impact of the sequential or simultaneous solubilization of xylan on the hydrolysis of cellulose by purified enzymes were investigated. The results showed that the removal of acetyl groups in xylan by AXE increased the accessibility of xylan to xylanase and improved the hydrolysis of xylan in pretreated wheat straw and giant reed. Solubilization of xylan led to an increased accessibility of cellulose to cellulases and thereby increased the hydrolysis extent of cellulose. A clear synergistic effect between cellulases and xylanolytic enzymes was observed. The highest hydrolysis yield of cellulose was obtained with a simultaneous use of cellulases, xylanase and AXE, indicating the presence of acetylated xylan within the cellulose matrix. Acetylated xylobiose and acetylated xylotriose were produced from xylan without AXE, as confirmed by atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry.
The results in this paper demonstrate that supplementation of xylanase with AXE enhances the solubilization of xylan to some extent and, consequently, increases the subsequent hydrolysis of cellulose. The highest hydrolysis yield was, however, obtained by simultaneous hydrolysis of xylan and cellulose, indicating a layered structure of cellulose and xylan chains in the cell wall substrate. AXE has an important role in the hydrolysis of lignocellulosic materials containing acetylated xylan.
Our study had two objectives: a) to systematically identify all existing systematic reviews of Chinese herbal medicines (CHM) published in Cochrane Library; b) to assess the methodological quality of included reviews.
We performed a systematic search of the Cochrane Database of Systematic Reviews (CDSR, Issue 5, 2010) to identify all reviews of CHM. A total of fifty-eight reviews were eligible for our study. Twenty-one of the included reviews had at least one Traditional Chinese Medicine (TCM) practitioner as its co-author. 7 reviews didn't include any primary study, the remaining reviews (n = 51) included a median of 9 studies and 936 participants. 50% of reviews were last assessed as up-to-date prior to 2008. The questions addressed by 39 reviews were broad in scope, in which 9 reviews combined studies with different herbal medicines. For OQAQ, the mean of overall quality score (item 10) was 5.05 (95% CI; 4.58-5.52). All reviews assessed the methodological quality of primary studies, 16% of included primary studies used adequate sequence generation and 7% used adequate allocation concealment. Of the 51 nonempty reviews, 23 reviews were reported as being inconclusive, while 27 concluded that there might be benefit of CHM, which was limited by the poor quality or inadequate quantity of included studies. 58 reviews reported searching a median of seven electronic databases, while 10 reviews did not search any Chinese database.
Now CDSR has included large numbers of CHM reviews, our study identified some areas which could be improved, such as almost half of included reviews did not have the participation of TCM practitioners and were not up-to-date according to Cochrane criteria, some reviews pooled the results of different herbal medicines and ignored the searching of Chinese databases.
In the hydrolysis of lignocellulosic materials, thermostable enzymes decrease the amount of enzyme needed due to higher specific activity and elongate the hydrolysis time due to improved stability. For cost-efficient use of enzymes in large-scale industrial applications, high-level expression of enzymes in recombinant hosts is usually a prerequisite. The main aim of the present study was to compare the biochemical and hydrolytic properties of two thermostable recombinant glycosyl hydrolase families 10 and 11 (GH10 and GH11, respectively) xylanases with respect to their potential application in the hydrolysis of lignocellulosic substrates.
The xylanases from Nonomuraea flexuosa (Nf Xyn11A) and from Thermoascus aurantiacus (Ta Xyn10A) were purified by heat treatment and gel permeation chromatography. Ta Xyn10A exhibited higher hydrolytic efficiency than Nf Xyn11A toward birchwood glucuronoxylan, insoluble oat spelt arabinoxylan and hydrothermally pretreated wheat straw, and it produced more reducing sugars. Oligosaccharides from xylobiose to xylopentaose as well as higher degree of polymerization (DP) xylooligosaccharides (XOSs), but not xylose, were released during the initial hydrolysis of xylans by Nf Xyn11A, indicating its potential for the production of XOS. The mode of action of Nf Xyn11A and Ta Xyn10A on glucuronoxylan and arabinoxylan showed typical production patterns of endoxylanases belonging to GH11 and GH10, respectively.
Because of its high catalytic activity and good thermostability, T. aurantiacus xylanase shows great potential for applications aimed at total hydrolysis of lignocellulosic materials for platform sugars, whereas N. flexuosa xylanase shows more significant potential for the production of XOSs.
Chronic heart failure (CHF) is a global public health problem. Therefore, novel and effective drugs that show few side-effects are needed. Early literature studies indicated that Huangqi injection is one of the most commonly used traditional Chinese patent medicines for CHF in China. As a large number of clinical studies has been carried out and published, it is essential to evaluate the effectiveness and safety of Huangqi injection. Therefore, we carried out this systematic review under the support of the framework of the Joint Sino-Italian Laboratory (JoSIL).
To evaluate the efficacy and safety of Huangqi injection for CHF according to the available scientific knowledge.
An extensive search including PubMed, EMBASE, CBM, the Cochrane Library and Chinese literature databases was performed up to July 2008. Clinical trials regarding Huangqi injection for the treatment of CHF were searched for, irrespective of languages. The quality of each trial was assessed according to the Cochrane Reviewers' Handbook 5.0, and RevMan 5.0 provided by the Cochrane Collaboration and STATA 9.2 were used for data analysis.
After selection of 1,205 articles, 62 RCTs and quasi-RCTs conducted in China and published in Chinese journals were included in the review. The methodological quality of the trials was low. In most trials inclusion and exclusion criteria were not specified. Furthermore, only one study evaluated the outcomes for drug efficacy after an adequate period of time. For these reasons and because of the different baseline characteristics we did not conduct a meta-analysis.
Although available studies are not adequate to draw a conclusion on the efficacy and safety of Huangqi injection (a traditional Chinese patent medicine), we hope that our work could provide useful experience on further studies on Huangqi injections. The overall level of TCM clinical research needs to be improved so that the efficacy of TCM can be evaluated by the international community and possibly some TCM can enter into the international market.
The study aimed to examine the effect of household and community characteristics on financial catastrophe and impoverishment due to health payment in Western and Central Rural China.
A household survey was conducted in 2008 in Hebei and Shaanxi provinces and the Inner Mongolia Autonomous Region using a multi-stage sampling technique. Independent variables included village characteristics, household income, chronic illness status, health care use and health spending. A composite contextual variable, named village deprivation, was derived from socio-economic status and availability of health care facilities in each village using factor analysis. Dependent variables were whether household health payment was more than 40% of household's capacity to pay (catastrophic health payment) and whether household per capita income was put under Chinese national poverty line (1067 Yuan income per year) after health spending (impoverishment). Mixed effects logistic regression was used to assess the effect of the independent variables on the two outcomes.
Households with low per capita income, having elderly, hospitalized or chronically ill members, and whose head was unemployed were more likely to incur financial catastrophe and impoverishment due to health expenditure. Both catastrophic and impoverishing health payments increased with increased village deprivation. However, the presence of a village health clinic had no effect on the two outcomes, nor did household enrollment in the New Rural Cooperative Medical Scheme (national health insurance).
Village deprivation independently increases the risk for financial hardship due to health payment after adjusting for known household-level factors. This suggests that policy makers need to view the individual, household and village as separate units for policy targeting.
Thermostable enzymes have several benefits in lignocellulose processing. In particular, they potentially allow the use of increased substrate concentrations (because the substrate viscosity decreases as the temperature increases), resulting in improved product yields and reduced capital and processing costs. A short pre-hydrolysis step at an elevated temperature using thermostable enzymes aimed at rapid liquefaction of the feedstock is seen as an attractive way to overcome the technical problems (such as poor mixing and mass transfer properties) connected with high initial solid loadings in the lignocellulose to ethanol process.
The capability of novel thermostable enzymes to reduce the viscosity of high-solid biomass suspensions using a real-time viscometric measurement method was investigated. Heterologously expressed enzymes from various thermophilic organisms were compared for their ability to liquefy the lignocellulosic substrate, hydrothermally pretreated wheat straw. Once the best enzymes were identified, the optimal temperatures for these enzymes to decrease substrate viscosity were compared. The combined hydrolytic properties of the thermostable preparations were tested in hydrolysis experiments. The studied mixtures were primarily designed to have good liquefaction potential, and therefore contained an enhanced proportion of the key liquefying enzyme, EGII/Cel5A.
Endoglucanases were shown to have a superior ability to rapidly reduce the viscosity of the 15% (w/w; dry matter) hydrothermally pretreated wheat straw. Based on temperature profiling studies, Thermoascus aurantiacus EGII/Cel5A was the most promising enzyme for biomass liquefaction. Even though they were not optimized for saccharification, many of the thermostable enzyme mixtures had superior hydrolytic properties compared with the commercial reference enzymes at 55°C.
To reduce variability of Cobb angle measurement for scoliosis assessment, a computerized method was developed. This method automatically measured the Cobb angle on spinal posteroanterior radiographs after the brightness and the contrast of the image were adjusted, and the top and bottom of the vertebrae were selected. The automated process started with the edge detection of the vertebra by Canny edge detector. After that, the fuzzy Hough transform was used to find line structures in the vertebral edge images. The lines that fitted to the endplates of vertebrae were identified by selecting peaks in Hough space under the vertebral shape constraints. The Cobb angle was then calculated according to the directions of these lines. A total of 76 radiographs were respectively analyzed by an experienced surgeon using the manual measurement method and by two examiners using the proposed method twice. Intraclass correlation coefficients (ICC) showed high agreement between automatic and manual measurements (ICCs > 0.95). The mean absolute differences between automatic and manual measurements were less than 5°. In the interobserver analyses, ICCs were higher than 0.95, and mean absolute differences were less than 5°. In the intraobserver analyses, ICCs were 0.985 and 0.978, respectively, for each examiner, and mean absolute differences were less than 3°. These results demonstrated the validity and reliability of the proposed method.
Cobb angle; scoliosis; fuzzy Hough transform (FHT); shape prior; radiograph
Pre-diabetes is a growing health concern where a large percentage of these patients develop full type 2 diabetes. Effective interventions on pre-diabetes can prevent or delay the occurrence or development of diabetes. Pharmaco-dynamics and pre-clinical of JinQi-Jiangtang tablets (JQJT) suggest that it could be benefit for pre-diabetes.
Randomized controlled trial (RCT) is implemented in this study. The study term is 24 months (12 months for intervention and 12 months for follow up). Participants are recruited from four cities of China: Beijing, Tianjin, Xi'an and Nanning. Four hundred participants are randomized to treatment group (JQJT tablets) and control group (Placebo); two hundred participants each. People being included in this study must have been diagnosed as pre-diabetes via western medicine criteria and traditional Chinese medicine (TCM) criteria. The end-point indexes include: incidence of diabetes mellitus and reversion rate. Primary outcome indexes include: oral glucose tolerance test; insulin releasing test; glycosylated hemoglobin (HA1c). Secondary outcome indexes include: score of the Short Form 36 Health Survey Questionnaire (SF-36); score of TCM symptoms; blood lipid test. Indexes of safety include: general medical examination; blood and urine regular test; electrocardiogram (ECG), liver function (ALT) and renal function (BUN, Creatinine) test; record of adverse event, such as headache, faint, etc. Qualitative control will be implemented and a number of standard operating processes (SOPs) will be formed throughout the study: laboratory quality control measures; compliance control for researchers and participants; researcher training before study; supervision; investigational drug management and others.
The aim of this study is to evaluate the effectiveness and safety of JinQi JiangTang (JQJT) tablets for the treatment of patients with pre-diabetes.
Chinese clinical trials register ChiCTR-TRC-00000401
The New Rural Cooperative Medical Scheme (NRCMS, voluntary health insurance) and the Medical Financial Assistance (MFA, financial relief program) were established in 2003 for rural China. The aim of this study was to document their coverage, assess their effectiveness on access to in-patient care and protection against financial catastrophe and household impoverishment due to health spending, and identify the factors predicting impoverishment with and without these schemes.
A cross-sectional household survey was conducted in 2008 in Hebei and Shaanxi provinces and the Inner Mongolia Autonomous Region using a multi-stage sampling technique. Information on personal demographic characteristics, chronic illness status, health care use, household expenditure, and household health spending were collected by interview.
NRCMS covered 90.8% of the studied individuals and among the designated poor, 7.6% had their premiums paid by MFA. Of those referred for hospitalization in the year prior to the interview, 34.3% failed to comply, mostly (80.2%) owing to financial constraints. There was no significant difference in the unmet need for admission between the insured with NRCMS and the uninsured. Before reimbursement, the incidence of catastrophic health payment (household health spending more than 40% of household's capacity to pay) and medical impoverishment (household per capita income falling below the poverty line due to medical expense) was 14.3% and 8.2%, respectively. NRCMS prevented 9.9% of the households from financial catastrophe and 7.7% from impoverishment, whereas MFA kept just one household from impoverishment and had no effect on financial catastrophe. Household per capita expenditure and household chronic disease proportion (proportion of members of a household with chronic illness) were the most important determinants of the unmet need for admission, risk of being impoverished and the chance of not being saved from impoverishment.
The coverage of NRCMS among the rural population was high but not adequate to improve access to in-patient care and protect against financial catastrophe and household impoverishment due to health payment, especially for the poor and the chronically ill. Furthermore, MFA played almost no such role; therefore, the current schemes need to be improved.
LKB1, a master kinase that controls at least 13 downstream protein kinases including the AMP-activated protein kinase (AMPK), resides mainly in the nucleus. A key step in LKB1 activation is its export from the nucleus to the cytoplasm. Here, we identified S307 of LKB1 as a putative novel phosphorylation site which is essential for its nucleocytoplasmic transport. In a cell-free system, recombinant PKC-ζ phosphorylates LKB1 at S307. AMPK-activating agents stimulate PKC-ζ activity and LKB1 phosphorylation at S307 in endothelial cells, hepatocytes, skeletal muscle cells, and vascular smooth muscle cells. Like the kinase-dead LKB1 D194A mutant (mutation of Asp194 to Ala), the constitutively nucleus-localized LKB1 SL26 mutant and the LKB1 S307A mutant (Ser307 to Ala) exhibit a decreased association with STRADα. Interestingly, the PKC-ζ consensus sequence surrounding LKB1 S307 is disrupted in the LKB1 SL26 mutant, thus providing a likely molecular explanation for this mutation causing LKB1 dysfunction. In addition, LKB1 nucleocytoplasmic transport and AMPK activation in response to peroxynitrite are markedly reduced by pharmacological inhibition of CRM1, which normally facilitates nuclear export of LKB1-STRAD complexes. In comparison to the LKB1 wild type, the S307A mutant complexes show reduced association with CRM1. Finally, adenoviral overexpression of wild-type LKB1 suppresses, while the LKB1 S307A mutant increases, tube formation and hydrogen peroxide-enhanced apoptosis in cultured endothelial cells. Taken together, our results suggest that, in multiple cell types the signaling pathways engaged by several physiological stimuli converge upon PKC-ζ-dependent LKB1 phosphorylation at S307, which directs the nucleocytoplasmic transport of LKB1 and consequent AMPK activation.
OBJECTIVE—Recent evidence suggests that the AMP-activated protein kinase (AMPK) is an important therapeutic target for diabetes. The present study was conducted to determine how AMPK activation suppressed tyrosine nitration of prostacyclin synthase in diabetes.
RESEARCH DESIGN AND METHODS—Confluent human umbilical vein endothelial cells (HUVECs) or mice were treated with 5-amino-4-imidazole carboxamide riboside (AICAR) for the detection of AMPK phosphorylation and the expression of mitochondrial uncoupling protein (UCP)-2.
RESULTS—Exposure of HUVECs to high glucose (30 mmol/l) increased superoxide anions (O2·−) and prostacyclin synthase nitration. In addition, overexpression of constitutively active AMPK (Ad-CA-AMPK) or the addition of AICAR reduced both O2·− and prostacyclin synthase nitration caused by high glucose, whereas adenoviral overexpression of dominant-negative AMPK mutants (Ad-DN-AMPK) enhanced the latter effects of high glucose. Exposure of HUVECs to either AICAR or metformin caused AMPK-dependent upregulation of both UCP-2 mRNA and UCP-2 protein. Furthermore, overexpression of UCP-2 significantly ablated both O2·− and prostacyclin synthase nitration triggered by high glucose. Furthermore, overexpression of Ad-CA-AMPK increased, whereas overexpression of Ad-DN-AMPK inhibited AICAR-induced phosphorylation of p38 kinase at Thr180/Tyr182. Inhibition of p38 kinase with SB239063, which had no effect on AICAR-induced AMPK-Thr172 phosphorylation, dose dependently suppressed AICAR-induced upregulation of UCP-2, suggesting that AMPK lies upstream of p38 kinase. Finally, AICAR markedly increased UCP-2 expression and reduced both O2·− and prostacyclin synthase nitration in diabetic wild-type mice but not in their AMPKα2-deficient counterparts in vivo.
CONCLUSIONS—We conclude that AMPK activation increases UCP-2, resulting in the inhibition of both O2·− and prostacyclin synthase nitration in diabetes.
Rural township health centres and urban community health centres play a crucial role in the delivery of primary health care in China. Over the past two-and-a-half decades, these health institutions have not been as well developed as high-level hospitals. The limited availability and low qualifications of human resources in health are among the main challenges facing lower-level health facilities. This paper aims to analyse the mobility of health workers in township and community health centres.
Data used in this paper come from a nationwide survey of health facilities in 2006. Ten provinces in different locations and of varying levels of economic development were selected. From these provinces, 119 rural township health centres and 89 urban community health centres were selected to participate in a questionnaire survey. Thirty key informants were selected from these health facilities to be interviewed.
In 2005, 8.1% and 8.9% of health workers left township and community health centres, respectively. The health workers in rural township health centres had three to 13 years of work experience and typically had received a formal medical education. The majority of the mobile health workers moved to higher-level health facilities; very few moved to other rural township health centres. The rates of workers leaving township and community health centres increased between 2000 and 2005, with the main reasons for leaving being low salaries, limited opportunities for professional development and poor living conditions.
In China, primary health workers in township health centres and community health centres move to higher-level facilities due to low salaries, limited opportunities for promotion and poor living conditions. The government already has policies in place to counteract this migration, but it must step up enforcement if rural township health centres and urban community centres are to retain health professionals and recruit qualified health workers.
Gangliosides are sialic acid containing glycosphingolipids that are ubiquitously distributed on vertebrate plasma membranes. GM3, a precursor for most of the more complex ganglioside species, is synthesized by GM3 synthase. Although total ganglioside levels are significantly higher in breast tumor tissue than in normal mammary tissue, the roles played by gangliosides in breast cancer formation and metastasis are not clear.
To investigate the roles of gangliosides in breast tumor development, GM3 synthase was silenced in the highly metastatic 4T1 cells and over-expressed in the non-metastatic 67NR cells. The behavior of breast cancer cells was examined in vitro using migration assay, invasion assay, and soft agar assay. Tumor formation and metastasis in vivo were examined using a well established mouse mammary tumor model.
GM3 synthase silencing in 4T1 cells significantly inhibited cell migration, invasion and anchorage-independent growth in vitro, and lung metastasis in vivo. In addition, over-expression of GM3 synthase in nonmetastatic 67NR cells significantly induced cell migration and anchorage-independent growth. Further studies indicated that activation of the phosphoinositide-3 kinase/Akt pathway, and consequently inhibition of nuclear factor of activated T cell (NFAT)1 expression, could be the mechanism underlying the suppression of breast cancer migration/invasion induced by GM3 synthase silencing.
Our findings indicate that GM3 synthase silencing suppressed lung metastasis in murine breast cancer cells. The molecular mechanism that underlies GM3 synthase mediated migration and invasion was inhibition of the phosphoinositide-3 kinase/Akt pathway. The findings suggest that GM3 synthase may be of value as a therapeutic target in breast cancer.
Oxidation and glycation of low-density lipoprotein (LDL) promote vascular injury in diabetes; however, the mechanisms underlying this effect remain poorly defined. The present study was conducted to determine the effects of ‘heavily oxidized’ glycated LDL (HOG-LDL) on endothelial nitric oxide synthase (eNOS) function. Exposure of bovine aortic endothelial cells with HOG-LDL reduced eNOS protein levels in a concentration- and time-dependent manner, without altering eNOS mRNA levels. Reduced eNOS protein levels were accompanied by an increase in intracellular Ca2+, augmented production of reactive oxygen species (ROS) and induction of Ca2+-dependent calpain activity. Neither eNOS reduction nor any of these other effects were observed in cells exposed to native LDL. Reduction of intracellular Ca2+ levels abolished eNOS reduction by HOG-LDL, as did pharmacological or genetic through calcium channel blockers or calcium chelator BAPTA or inhibition of NAD(P)H oxidase (with apocynin) or inhibition of calpain (calpain 1-specific siRNA). Consistent with these results, HOG-LDL impaired acetylcholine-induced endothelium-dependent vasorelaxation of isolated mouse aortas, and pharmacological inhibition of calpain prevented this effect. HOG-LDL may impair endothelial function by inducing calpain-mediated eNOS degradation in a ROS- and Ca2+-dependent manner.
calcium homeostasis; calpain activation; endothelium dysfunction; eNOS, heavily oxidized and glycated-LDL (HOG-LDL); nitric oxide