An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich information content of micrometeorological flux measurements.

An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich information content of micrometeorological flux measurements.

AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury

We evaluated the effect of AAV2- and 17-AAG (17-N -allylamino-17-demethoxygeldanamycin)-mediated upregulation of Hsp70 expression on the survival of retinal ganglion cells (RGCs) injured by optic nerve crush (ONC). AAV2-Hsp70 expression in the retina was primarily observed in the ganglion cell layer. Approximately 75% of all transfected cells were RGCs. RGC survival in AAV2-Hsp70 injected animals was increased by an average of 110% 2 weeks after the axonal injury compared to the control. The increase in cell numbers was not even across the retinas with a maximum effect of approximately 306% observed in the inferior quadrant. 17-AAG-mediated expression of Hsp70 has been associated with cell protection in various models of neurodegenerative diseases. We show here that a single intravitreal injection of 17-AAG (0.2 ug/ul) results in an increased survival of ONC injured RGCs by approximately 49% compared to the vehicle-treated animals. Expression of Hsp70 in retinas of 17-AAG-treated animals was upregulated approximately by 2-fold compared to control animals. Our data support the idea that the upregulation of Hsp70 has a beneficial effect on the survival of injured RGCs, and the induction of this protein could be viewed as a potential neuroprotective strategy for optic neuropathies.

Stapled vs hand suture closure of loop ileostomy: a meta-analysis

AIM

Loop ileostomies are widely used in colorectal surgery to reduce the consequences of distal anastomotic failure. The optimal surgical technique for their closure has yet not been defined. A meta-analysis was performed to compare the outcome after stapled or hand sutured ileostomy closure.

METHOD

An electronic literature search of EMBASE, PubMed and the Cochrane Library was undertaken to identify studies reporting stapled and hand sutured ileostomy closure. End-points included postoperative small bowel obstruction (SBO), anastomotic leakage, wound infection, overall postoperative complications, operation time, hospital stay and surgery-related cost.

RESULTS

Fourteen studies including 5084 patients were identified. Meta-analysis showed that stapled closure was associated with a lower rate of SBO overall (OR = 0.56, P < 0.00001) and early (within 30 days of closure) SBO (OR = 0.51, P < 0.00001). This difference persisted for direct ileostomy closure (OR = 0.62, P = 0.02) or closure with bowel resection and hand sewn anastomosis (OR = 0.44, P < 0.00001). Stapled closure required a shorter inpatient stay (mean difference -1.22, P < 0.0001) and operating time (mean difference -11.21, P = 0.01). No significant difference was noted between the two techniques in terms of anastomotic leakage, wound infection, overall complications or cost.

CONCLUSION

Stapled side-to-side anastomosis is associated with fewer complications, especially SBO, than hand sewn ileostomy closure by direct suture or resection and anastomosis. It is quicker to perform and associated with fewer postoperative bowel obstructions.

Oral treatment with SEW2871, a sphingosine-1-phosphate type 1 receptor agonist, ameliorates experimental colitis in interleukin-10 gene deficient mice

SEW2871, a selective sphingosine-1-phosphate type 1 receptor (S1P1) agonist, has been shown to be effective in protecting kidneys against ischaemia-reperfusion injury by reducing CD4(+) T cell infiltration in mice. However, the effects of SEW2871 on colitis remain unclear. The aim of this study was to investigate the effects of SEW2871 on established colitis in interleukin (IL)-10 gene-deficient (IL-10(-/-)) mice, a murine model of Crohn's disease (CD). SEW2871 was administered by gavage at a dose of 20 mg/kg/day for 2 weeks to IL-10(-/-) mice. Severity of colitis, serum amyloid A, tissue myeloperoxidase (MPO), T cells in blood and colon lamina propria (LP) and proinflammatory cytokine productions were evaluated. Furthermore, the phospho-signal transducer and activator of transcription (STAT)-3 (p-STAT-3) expression in lymphocytes isolated from colon LP was also assessed. The 2-week administration of SEW2871 ameliorated established colitis in IL-10(-/-) mice, associated with a reduction of serum amyloid A concentration, a decreased colon MPO concentration, a depletion of the peripheral CD4(+) CD45(+) T cells and a reduction of the homing of T cells into colon LP. Moreover, typical cytokines of T helper type 1 (Th1) and Th17 cells and p-STAT-3 expression were also suppressed by SEW2871 treatment. SEW2871 treatment ameliorates established experimental colitis in IL-10(-/-) mice, which may provide a new therapeutic approach for human CD therapy.

Intestinal dysbacteriosis contributes to decreased intestinal mucosal barrier function and increased bacterial translocation

The purpose of this study was to determine the effect of colistin-induced intestinal dysbacteriosis on intestinal mucosal barrier function and bacterial translocation in a mouse model. Colistin or saline was administered orally for 7 days, and populations of viable organisms from the caecal mucosa and its content, the ileal segments, the mesenteric lymph nodes (MLNs) and the internal organs were prepared for examination. In the intestinal dysbacteriosis model, intestinal barrier dysfunction was observed and associated with increased bacterial translocation to extraintestinal sites. The extent of bacterial translocation to the MLNs and internal organs in the colistin group was significantly higher than in the saline group. Colistin-induced intestinal dysbacteriosis was shown to injure the intestinal mucosa barrier function and increase bacterial dislocation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Colistin has been reported to be effective in selective digestive decontamination (SDD), which is an infection prevention measure used in the treatment of certain patients in intensive care. We are the first to report that colistin-induced intestinal dysbacteriosis can injure intestinal mucosal barrier function and increase bacterial translocation, whereas a high dose of colistin does not damage the intestinal mucosal barrier in germ-free (GF) mice raised in a GF environment. These results may indicate that prolonged use of a high dose of a SDD medication should be carefully considered.

H19 DMR methylation correlates to the progression of esophageal squamous cell carcinoma through IGF2 imprinting pathway

BACKGROUND

H19 gene has been proved to be essential for human tumor growth which contains CpG rich regions. Imprinted gene expression in many cancers is usually associated with the function of methylation. We performed this study to better understand wether H19 DMR methylation correlates to the progression of esophageal squamous cell carcinoma through IGF2 imprinting pathway.

METHODS

LOI of IGF2 was detected in 276 samples, which were determined as heterozygote with ApaI polymorphism in exon 9 of IGF2 by PCR-RFLP and RT-PCR-RFLP. Methylation status of H19 DMR in informative samples was analyzed by bisulfite sequencing PCR. IGF2 expression was examined by real-time PCR and IHC.

RESULTS

208 ESCC patients were informative for ApaI polymorphism. 92 tumor and 30 normal tissues showed IGF2 LOI. Methylation status of H19 CBS6 was higher in patients with IGF2 LOI compared to patients with IGF2 MOI (p < 0.05). IGF2 expression in patients with IGF2 LOI was higher than patients with IGF2 MOI (p < 0.05) which was correlated with lymph node involvement, neoplastic grade and metastasis (p < 0.05).

CONCLUSIONS

Our results suggested that H19 CBS6 hypermethylation is related to the LOI of IGF2 which usually leads to an overexpression of IGF2, playing important roles in the occurrence, development as well as metastasis of ESCC. Therefore, H19 CBS6 methylation potentially represents a novel clinically relevant epigenetic marker to identify individuals at increased risk for the occurrence, progression and prognosis of ESCC.

Anisomycin induces apoptosis of glucocorticoid resistant acute lymphoblastic leukemia CEM-C1 cells via activation of mitogen-activated protein kinases p38 and JNK

Glucocorticoids (GCs) resistance is frequently encountered in children with acute lymphoblastic leukemia (ALL), especially in T-ALL, which usually results in failure of treatment. To find new agent to overcome GC resistance of ALL is an urgent problem. Here we investigated potential effect of anisomycin on GC-resistant T-ALL CEM-C1 cells and explored involved molecular mechanisms. Dramatic growth inhibition and apoptosis in GC resistant CEM-C1 cells and GC-sensitive CEM-C7 cells induced by anisomycin were observed, which presented in a concentration- and time-dependent manner. Correspondingly, anisomycin induced cleaved caspase-3 and up-regulation of pro-apoptotic proteins (BimEL and Bad), meanwhile down-regulation of anti-apoptotic proteins (Mcl-1 and Bcl-2), both in a dose- and time-dependent manner in GC resistant CEM-C1 cells. Anisomycin also induced cell cycle arrest at G0/G1 phase in CEM-C1 cells through increasing expressions of p21 and p27, and attenuating the expression of cyclinA. The rapid up-regulation of phosphorylated mitogen-activated protein kinases (MAPKs) p38 and Jun N-terminal kinase (JNK) were observed after CEM-C1 cells were incubated with anisomycin. The activation of p38 and JNK could be blocked by respective inhibitors (SB203580 for p38 and SP600125 for JNK) accompanied with the inhibition of apoptosis and changes of apoptosis associated proteins in CEM-C1 cells. These results suggested that anisomycin induced apoptosis of CEM-C1 cells via activation of p38 and JNK, and might be an attractive new agent for treatment of GC-resistant ALL.

Fiber-optic two-photon optogenetic stimulation

Optogenetic stimulation of genetically targeted cells is proving to be a powerful tool in the study of cellular systems, both in vitro and in vivo. However, most opsins are activated in the visible spectrum, where significant absorption and scattering of stimulating light occurs, leading to low penetration depth and less precise stimulation. Since we first (to the best of our knowledge) demonstrated two-photon optogenetic stimulation (TPOS), it has gained considerable interest in the probing of cellular circuitry by precise spatial modulation. However, all existing methods use microscope objectives and complex scanning beam geometries. Here, we report a nonscanning method based on multimode fiber to accomplish fiber-optic TPOS of cells.

Resveratrol attenuates hydrogen peroxide-induced apoptosis in human umbilical vein endothelial cells

BACKGROUND AND OBJECTIVES

  Vascular endothelium injury caused by reactive oxygen species (ROS) plays an initial role in the pathogenesis of atherosclerosis. Resveratrol, a natural polyphenolic compound, is well known to possess a variety of cardioprotective activities. In this study we first investigated the effects of resveratrol against apoptosis of human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H2O2) in vitro and the possible mechanisms.

MATERIALS AND METHODS

HUVECs were pre-incubated with resveratrol (0.5-10 microM) for 120 min, and then challenged with 100 microM H2O2 for 30 min. The cell viability was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The superoxide dismutase (SOD) activities and the reduced glutathione (GSH) contents were measured spectrophotometrically by using commercially available kits. The apoptosis of HUVECs was detected by Hoechst 33258 and Annexin-V/PI staining by flow cytometry staining using Fluorescence microscope. We also measured the mitochondrial membrane potential with the fluorescent probe JC-1 through Fluorescence microscope.

RESULTS

The study showed that incubation with resveratrol caused significant increase of the viability of HUVECs and the SOD activities and GSH contents, and decrease of cell apoptosis induced by H2O2, which was accompanied with the restoration of the mitochondrial membrane potential.

CONCLUSIONS

Our data suggested that resveratrol protected HUVECs against apoptosis induced by H2O2 through enhancing the antioxidant defenses, and inhibiting the degression of the mitochondrial membrane potential.  

Epigenetic screen identifies genotype-specific promoter DNA methylation and oncogenic potential of CHRNB4

Genome-wide association studies have highlighted three major lung cancer susceptibility regions at 15q25.1, 5p15.33 and 6p21.33. To gain insight into the possible mechanistic relevance of the genes in these regions, we investigated the regulation of candidate susceptibility gene expression by epigenetic alterations in healthy and lung tumor tissues. For genes up- or downregulated in lung tumors the influence of genetic variants on DNA methylation was investigated and in vitro studies were performed.

We analyzed 394 CpG units within 19 CpG islands in the susceptibility regions in a screening set of 34 patients. Significant findings were validated in an independent patient set (n=50) with available DNA and RNA. The most consistent overall DNA methylation difference between tumor and adjacent normal tissue on 15q25 was tumor hypomethylation in the promoter region of CHRNB4 with a median difference of 8% (p<0.001) which resulted in overexpression of the transcript in tumors (p<0.001). Confirming previous studies we also found hypermethylation in CHRNA3 and TERT with significant expression changes. Decitabine treatment of H1299 cells resulted in reduced methylation levels in gene promoters, elevated transcript levels of CHRNB4 and CHRNA3 and a slight downregulation of TERT demonstrating epigenetic regulation of lung cancer cells. SNPs rs421629 on 5p15.33 and rs1948, rs660652, rs8040868 and rs2036527 on 15q25.1, previously identified as lung cancer risk or nicotine addiction modifiers were associated with tumor DNA methylation levels in the promoters of TERT and CHRNB4 (p<0.001) respectively in two independent sample sets (n=82; n=150). In addition, CHRNB4 knock down in two different cell lines (A549 and H1299) resulted in reduced proliferation (p_A549<0.05;p_H1299L<0.001) and propensity to form colonies in H1299 cells.

These results suggest epigenetic deregulation of nicotinic acetylcholinereceptor subunit (nAChR) genes which in the case of CHRNB4 is strongly associated with genetic lung cancer susceptibility variants and a functional impact on tumorigenic potential.

Cordycepin as a sensitizer to tumour necrosis factor (TNF)-α-induced apoptosis through eukaryotic translation initiation factor 2α (eIF2α)- and mammalian target of rapamycin complex 1 (mTORC1)-mediated inhibition of nuclear factor (NF)-κB

Cordycepin (3'-deoxyadenosine) is one of the major bioactive substances produced by Cordyceps militaris, a traditional medicinal mushroom. Cordycepin possesses several biological activities, including both pro-apoptotic and anti-apoptotic properties. In the present report, we investigated an effect of cordycepin on the survival of cells exposed to tumour necrosis factor (TNF)-α. We found that subtoxic doses of cordycepin increased susceptibility of cells to TNF-α-induced apoptosis. It was associated with suppression of nuclear factor-κB (NF-κB), a major prosurvival component involved in TNF-α signalling. The adenosine transporter and A₃ adenosine receptor, but not A₁ and A₂ adenosine receptors, mediated both anti-NF-κB and pro-apoptotic effects. We found that cordycepin had the potential to phosphorylate eukaryotic translation initiation factor 2α (eIF2α) and that activation of eIF2α mimicked the suppressive effect of cordycepin on the NF-κB pathway. Furthermore, activation of eIF2α sensitized cells to TNF-α-induced apoptosis. To identify molecular events downstream of eIF2α, the role of mammalian target of rapamycin complex 1 (mTORC1) was examined. Selective activation of ₃eIF2α, as well as treatment with cordycepin, caused phosphorylation of mTORC1. Rapamycin, an inhibitor of mTORC1, significantly reversed the suppressive effects of eIF2α on NF-κB. These results suggest that cordycepin sensitizes cells to TNF-α-induced apoptosis, at least in part, via induction of the eIF2α-mTORC1 pathway and consequent suppression of NF-κB.