GNAI2 Is a Risk Factor for Gastric Cancer: Study of Tumor Microenvironment (TME) and Establishment of Immune Risk Score (IRS)

Purpose

Although the G protein subunit α i2 (GNAI2) is upregulated in multiple cancers, its prognostic value and exact role in the development of gastric cancer (GC) remain largely unknown.

Methods

This study evaluated the effect of GNAI2 on the tumor microenvironment (TME) in GC, constructed an immune risk score (IRS) model based on differentially-expressed immune genes, and systematically correlated GNAI2 and epigenetic factor expression patterns with TME and IRS. Also, RT-qPCR, flow cytometry, Western blotting (WB), and transwell assays were carried out to explore the regulatory mechanism of GNAI2 in GC.

Results

High GNAI2 expression was associated with poor prognosis. Cytokine activation, an increase in tumor-infiltrating immune cells (TIIC), and the accumulation of regulatory T cells in the tumor immune cycle were all promoted by the TME, which was significantly associated with GNAI2 expression. Two different differentially expressed mRNA (DER) modification patterns were determined. These two DERs-clusters had significantly different TME cell infiltrations and were classified as either noninflamed or immune-inflamed phenotypes. The IRS model constructed using differentially expressed genes (DEGs) had great potential in predicting GC prognosis. The IRS model was also used in assessing clinicopathological features, such as microsatellite instability (MSI) status, epithelial-mesenchymal transition (EMT) status, clinical stages, tumor mutational burden (TMB), and tumor immune dysfunction and exclusion (TIDE) scores. Low IRS scores were associated with high immune checkpoint gene expression. Cell and animal studies confirmed that GNAI2 activated PI3K/AKT pathway and promoted the growth and migration of GC cells.

Conclusion

The IRS model can be used for survival prediction and GNAI2 serves as a candidate therapeutic target for GC patients.

N-n-Butyl haloperidol iodide ameliorates liver fibrosis and hepatic stellate cell activation in mice

N-n-Butyl haloperidol iodide (F₂) is a novel compound that has antiproliferative and antifibrogenic activities. In this study we investigated the therapeutic potential of F₂ against liver fibrosis in mice and the underlying mechanisms. Two widely used mouse models of fibrosis was established in mice by injection of either carbon tetrachloride (CCl₄) or thioacetamide (TAA). The mice received F₂ (0.75, 1.5 or 3 mg·kg^-1·d^-1, ip) for 4 weeks of fibrosis induction. We showed that F₂ administration dose-dependently ameliorated CCl₄- or TAA-induced liver fibrosis, evidenced by significant decreases in collagen deposition and c-Jun, TGF-β receptor II (TGFBR2), α-smooth muscle actin (α-SMA), and collagen I expression in the liver. In transforming growth factor beta 1 (TGF-β1)-stimulated LX-2 cells (a human hepatic stellate cell line) and primary mouse hepatic stellate cells, treatment with F₂ (0.1, 1, 10 μM) concentration-dependently inhibited the expression of α-SMA, and collagen I. In LX-2 cells, F₂ inhibited TGF-β/Smad signaling through reducing the levels of TGFBR2; pretreatment with LY2109761 (TGF-β signaling inhibitor) or SP600125 (c-Jun signaling inhibitor) markedly inhibited TGF-β1-induced induction of α-SMA and collagen I. Knockdown of c-Jun decreased TGF-β signaling genes, including TGFBR2 levels. We revealed that c-Jun was bound to the TGFBR2 promoter, whereas F₂ suppressed the binding of c-Jun to the TGFBR2 promoter to restrain TGF-β signaling and inhibit α-SMA and collagen I upregulation. In conclusion, the therapeutic benefit of F₂ against liver fibrosis results from inhibition of c-Jun expression to reduce TGFBR2 and concomitant reduction of the responsiveness of hepatic stellate cells to TGF-β1. F₂ may thus be a potentially new effective pharmacotherapy for human liver fibrosis.

Identification of Signature Genes in the PD-1 Relative Gastric Cancer Using a Combined Analysis of Gene Expression and Methylation Data

BACKGROUND

The morbidity and mortality rates for gastric cancer (GC) rank second among all cancers, indicating the serious threat it poses to human health, as well as human life. This study aims to identify the pathways and genes as well as investigate the molecular mechanisms of tumor-related genes in gastric cancer (GC).

METHOD

We compared differentially expressed genes (DEGs) and differentially methylated genes (DMGs) in gastric cancer and normal tissue samples using The Cancer Genome Atlas (TCGA) data. The Kyoto Encyclopedia of Gene and Genome (KEGG) and the Gene Ontology (GO) enrichment analysis' pathway annotations were conducted on DMGs and DEGs using a clusterProfiler R package to identify the important functions, as well as the biological processes and pathways involved. The intersection of the two was chosen and defined as differentially methylated and expressed genes (DMEGs). For DMEGs, we used the principal component analysis (PCA) to differentiate gastric cancer from adjacent samples. The linear discriminant analysis method was applied to categorize the samples using DMEGs methylation data and DMEGs expression profiles data and was validated using the leave-one-out cross-validation (LOOCV) method. We plotted the ROC curve for the classification and calculated the AUC (area under the ROC curve) value for a more intuitive view of the classification effect. We also used the NetworkAnalyst 3.0 tool to analyze DMEGs, using DrugBank to acquire information on protein-drug interactions and generate a network map of gene-drug interactions.

RESULTS

We identified a total of 971 DMGs in 188 PD-1 negative and 187 PD-1 positive gastric cancer samples obtained from TCGA. The KEGG and GO enrichment analysis showed the involvement of the regulation of ion transmembrane transport, collagen-containing extracellular matrix, cell-cell junction, and peptidase regulator activity. We simultaneously obtained 1,189 DEGs, out of which 986 were downregulated, while 203 were upregulated in tumors. The enriched analysis of the GO's and KEGG's pathways indicated that the most significant pathways included an intestinal immune network for IgA production, Staphylococcus aureus infection, cytokine-cytokine receptor interaction, and viral protein interaction with cytokine and cytokine receptor, which have previously been linked with gastric cancer. The compound DB01830 can bind well to the active site of the LCK protein and shows good stability, thus making it a potential inhibitor of the LCK protein. To observe the relationship between DMEGs' expression and prognosis, we observed 10 genes, among which were TRIM29, TSPAN8, EOMES, PPP1R16B, SELL, PCED1B, IYD, JPH1, CEACAM5, and RP11-44K6.2. Their high expressions were related to high risks. Besides, those genes were validated in different internal and external validation sets.

CONCLUSION

These results may provide potential molecular biological therapy for PD-1 negative gastric cancer.

Pharmacological and functional comparisons of α6/α3β2β3-nAChRs and α4β2-nAChRs heterologously expressed in the human epithelial SH-EP1 cell line

Neuronal nicotinic acetylcholine receptors containing α6 subunits (α6^*-nAChRs) show highly restricted distribution in midbrain neurons associated with pleasure, reward, and mood control, suggesting an important impact of α6^*-nAChRs in modulating mesolimbic functions. However, the function and pharmacology of α6^*-nAChRs remain poorly understood because of the lack of selective agonists for α6^*-nAChRs and the challenging heterologous expression of functional α6^*-nAChRs in mammalian cell lines. In particular, the α6 subunit is commonly co-expressed with α4^*-nAChRs in the midbrain, which masks α6^*-nAChR (without α4) function and pharmacology. In this study, we systematically profiled the pharmacology and function of α6^*-nAChRs and compared these properties with those of α4β2 nAChRs expressed in the same cell line. Heterologously expressed human α6/α3 chimeric subunits (α6 N-terminal domain joined with α3 trans-membrane domains and intracellular loops) with β2 and β3 subunits in the human SH-EP1 cell line (α6^*-nAChRs) were used. Patch-clamp whole-cell recordings were performed to measure these receptor-mediated currents. Functionally, the heterologously expressed α6^*-nAChRs exhibited excellent function and showed distinct nicotine-induced current responses, such as kinetics, inward rectification and recovery from desensitization, compared with α4β2-nAChRs. Pharmacologically, α6^*-nAChR was highly sensitive to the α6 subunit-selective antagonist α-conotoxin MII but had lower sensitivity to mecamylamine and dihydro-β-erythroidine. Nicotine and acetylcholine were found to be full agonists for α6^*-nAChRs, whereas epibatidine and cytisine were determined to be partial agonists. Heterologously expressed α6^*-nAChRs exhibited pharmacology and function distinct from those of α4β2-nAChRs, suggesting that α6^*-nAChRs may mediate different cholinergic signals. Our α6^*-nAChR expression system can be used as an excellent cell model for future investigations of α6^*-nAChR function and pharmacology.

[Preliminary study of whole-tumor volume analysis of mono-exponential and intravoxel incoherent motion models in the preoperative histologic grading of hepatocellular carcinoma]

Objective: To investigate the diagnostic performance of whole-tumor volume analysis of mono-exponential and intravoxel incoherent motion (IVIM)parameters in the preoperative grading of hepatocellular carcinoma (HCC). Methods: A total of 106 patients who undewent parital hepatectomy were prospectively enrolled and underwent with routine MR and IVIM examination.112 HCCs were confirmed by the surgical pathology.The original images of IVIM were imported into the GE AW 4.6 workstation.Two independent radiologist who were blinded to the histopathological results analyzed the data.Freehand ROI was used to cover the whole tumor volume, ADC, ADC(slow), ADC(fast) and f was calculated.Intra-class correlation coefficient (ICC) was used to evaluate the inter-observer agreement, One-way ANOVA and Kruskal-Wallis sign rank test were used to evaluate the difference of these parameters in grading HCC, Spearman correlation analysis was used to determine the correlation between these parameters and histologic grade, receiver operating characteristics (ROC) curves were performed to evaluate the diagnostic performance. Results: ICC value of ADC, ADC(slow), ADC(fast) and f were 0.948, 0.966, 0.901 and 0.940, respectively.Statistical significances were obtained from the ADC(slow)(R1: χ(2)=74.403, P<0.001; R2: F=44.973, P<0.001) and ADC (R1: χ(2)=52.987, P<0.001; R2: F=30.851, P<0.001) in grading HCC.Between the multiple-comparison in grading HCC, the ADC(slow) and ADC (except for E-S 3 and 4, R1: P=0.134; R2: P=0.069) also demonstrated a statistical significant difference (all P<0.05). Area under curve (AUC) value of two radiologists for ADC(slow) were 0.905 and 0.917, for ADC were 0.831 and 0.829, a negative correlation was obtained from the ADC and ADC(slow) (all P<0.05). Conclusion: Mono-exponential and intravoxel incoherent motion (IVIM) model can be used to evaluate the pathological differentiated grade of HCC, ADC and ADC(slow) value entailed the highest diagnostic performance.

Characterization and bioactivity of novel calcium antagonists - N-methoxy-benzyl haloperidol quaternary ammonium salt

BACKGROUND AND PURPOSE

Calcium antagonists play an important role in clinical practice. However, most of them have serious side effects. We have synthesized a series of novel calcium antagonists, quaternary ammonium salt derivatives of haloperidol with N-p-methoxybenzyl (X1), N-m-methoxybenzyl (X2) and N-o-methoxybenzyl (X3) groups. The objective of this study was to investigate the bioactivity of these novel calcium antagonists, especially the vasodilation activity and cardiac side-effects. The possible working mechanisms of these haloperidol derivatives were also explored.

EXPERIMENTAL APPROACH

Novel calcium antagonists were synthesized by amination. Compounds were screened for their activity of vasodilation on isolated thoracic aortic ring of rats. Their cardiac side effects were explored. The patch-clamp, confocal laser microscopy and the computer-fitting molecular docking experiments were employed to investigate the possible working mechanisms of these calcium antagonists.

RESULTS

The novel calcium antagonists, X1, X2 and X3 showed stronger vasodilation effect and less cardiac side effect than that of classical calcium antagonists. They blocked L-type calcium channels with an potent effect order of X1 > X2 > X3. Consistently, X1, X2 and X3 interacted with different regions of Ca2+-CaM-CaV1.2 with an affinity order of X1 > X2 > X3.

CONCLUSIONS

The new halopedidol derivatives X1, X2 and X3 are novel calcium antagonists with stronger vasodilation effect and less cardiac side effect. They could have wide clinical application.

Association between metabolic syndrome and vascular endothelium dysfunction in children and adolescents

We aimed at investigating the association between metabolic syndrome (MS) and vascular endothelial cell dysfunction (ECD) in children and adolescents. Sixty children (30 obese children and 30 children with MS) were included in this retrospective analysis. Thirty healthy subjects were randomly selected as the control group. A series of indices/biomarkers known to be related to MS/ECD were determined using ELISA. Correlations between the variables measured were analyzed. Compared with the control group, PAI-1, vWF, VE-cad, TM, and VEGF were significantly increased in the MS group (P < 0.05). Adolescents in the obese group had significantly increased levels of serum PAI-1, VE-cad, TM, and VEGF as compared with the control group (P < 0.05). Further, vWF in the obese and control groups did not differ significantly (P = 0.556). Our results suggest that ECD is correlated with MS in children and adolescents. Pathophysiological changes of the vascular endothelium may exist in obese children who have yet to develope MS. PAI-1, vWF, VE-cad, TM, and VEGF could be used as biomarkers for predicting ECD. ECD that develops in patients with MS may be associated with obesity, elevated blood lipid, elevated blood glucose, and higher blood pressure.

N-n-butyl haloperidol iodide inhibits H2O2-induced Na+/Ca2+-exchanger activation via the Na+/H+ exchanger in rat ventricular myocytes

N-n-butyl haloperidol iodide (F2), a novel compound, has shown palliative effects in myocardial ischemia/reperfusion (I/R) injury. In this study, we investigated the effects of F2 on the extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK)/Na(+)/H(+) exchanger (NHE)/Na(+)/Ca(2+) exchanger (NCX) signal-transduction pathway involved in H2O2-induced Ca(2+) overload, in order to probe the underlying molecular mechanism by which F2 antagonizes myocardial I/R injury. Acute exposure of rat cardiac myocytes to 100 μM H2O2 increased both NHE and NCX activities, as well as levels of phosphorylated MEK and ERK. The H2O2-induced increase in NCX current (I NCX) was nearly completely inhibited by the MEK inhibitor U0126 (1,4-diamino-2,3-dicyano-1,4-bis[o-aminophenylmercapto] butadiene), but only partly by the NHE inhibitor 5-(N,N-dimethyl)-amiloride (DMA), indicating the I NCX increase was primarily mediated by the MEK/mitogen-activated protein kinase (MAPK) pathway, and partially through activation of NHE. F2 attenuated the H2O2-induced I NCX increase in a concentration-dependent manner. To determine whether pathway inhibition was H2O2-specific, we examined the ability of F2 to inhibit MEK/ERK activation by epidermal growth factor (EGF), and NHE activation by angiotensin II. F2 not only inhibited H2O2-induced and EGF-induced MEK/ERK activation, but also completely blocked both H2O2-induced and angiotensin II-induced increases in NHE activity, suggesting that F2 directly inhibits MEK/ERK and NHE activation. These results show that F2 exerts multiple inhibitions on the signal-transduction pathway involved in H2O2-induced I NCX increase, providing an additional mechanism for F2 alleviating intracellular Ca(2+) overload to protect against myocardial I/R injury.

GSK256073, a selective agonist of G-protein coupled receptor 109A (GPR109A) reduces serum glucose in subjects with type 2 diabetes mellitus

AIMS

This clinical trial assessed whether a potent, selective GPR109A agonist, GSK256073, could, through inhibition of lipolysis, acutely improve glucose homeostasis in subjects with type 2 diabetes mellitus.

METHODS

Thirty-nine diabetic subjects were enrolled in the randomized, single-blind, placebo-controlled, three-period crossover trial. Each subject received placebo and two of four regimens of GSK256073 for 2 days. GSK256073 was dosed 5 mg every 12 h before breakfast and supper (BID), 10 mg every 24 h before breakfast (QD), 25 mg BID and 50 mg QD.

RESULTS

The change from baseline weighted mean glucose concentration for an interval from 24 to 48 h after the initial drug dose was significantly reduced for all GSK256073 regimens, reaching a maximum of -0.87 mmol/l (-1.20, -0.52) with the 25 mg BID dose. Sustained suppression of non-esterified fatty acid (NEFA) and glycerol concentrations was observed with all GSK256073 doses throughout the 48-h dosing period. Serum insulin and C-peptide concentrations fell in concert with glucose concentrations and calculated HOMA-IR scores decreased 27-47%, consistent with insulin sensitization. No marked differences were evident between either 10 and 50 mg total daily doses or QD versus BID dosing.

CONCLUSIONS

Administration of a GPR109A agonist for 2 days significantly decreased serum NEFA and glucose concentrations in diabetic subjects. Glucose improvements were associated with decreased insulin concentrations and measures of enhanced insulin sensitivity. Improved glucose control occurred with GSK256073 doses that were generally safe and not associated with events of flushing or gastrointestinal disturbances.

Effects of N-n-butyl haloperidol iodide on the rat myocardial sarcoplasmic reticulum Ca(2+)-ATPase during ischemia/reperfusion

We have previously shown that N-n-butyl haloperidol iodide (F(2)), a newly synthesized compound, reduces ischemia/reperfusion (I/R) injury by preventing intracellular Ca(2+) overload through inhibiting L-type calcium channels and outward current of Na(+)/Ca(2+) exchanger. This study was to investigate the effects of F(2) on activity and protein expression of the rat myocardial sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) during I/R to discover other molecular mechanisms by which F(2) maintains intracellular Ca(2+) homeostasis. In an in vivo rat model of myocardial I/R achieved by occluding coronary artery for 30-60 min followed by 0-120 min reperfusion, treatment with F(2) (0.25, 0.5, 1, 2 and 4 mg/kg, respectively) dose-dependently inhibited the I/R-induced decrease in SERCA activity. However, neither different durations of I/R nor different doses of F(2) altered the expression levels of myocardial SERCA2a protein. These results indicate that F(2) exerts cardioprotective effects against I/R injury by inhibiting I/R-mediated decrease in SERCA activity by a mechanism independent of SERCA2a protein levels modulation.

N-n-butyl haloperidol iodide preserves cardiomyocyte calcium homeostasis during hypoxia/ischemia

AIMS

N-n-Butyl haloperidol iodide (F(2)) is a novel compound derived from haloperidol. In our previous work, F(2) was found to be an L-type calcium channel blocker which played a protective role in rat heart ischemic-reperfusion injury in a dose-dependent manner. In the current study, we aimed to investigate the effects and some possible mechanisms of F(2) on calcium transients in hypoxic/ischemic rat cardiac myocytes.

METHODS AND RESULTS

Calcium transients' images of rat cardiac myocytes were recorded during simulated hypoxia, using a confocal calcium imaging system. The amplitude, rising time from 25% to 75% (RT25-75), decay time from 75% to 25% (DT75-25) of calcium transients, and resting [Ca(2+)](i) were extracted from the images by self-coding programs. In this study, hypoxia produced a substantial increase in diastolic [Ca(2+)](i) and reduced the amplitude of calcium transients. Both RT25-75 and DT75-25 of Ca(2+) transients were significantly prolonged. And F(2) could reduce the increase in resting [Ca(2+)](i)and the prolongation of RT25-75 and DT75-25 of Ca(2+) transients during hypoxia. F(2) also inhibited the reduction in amplitude of calcium transients which was caused by 30-min hypoxia. The activity of SERCA2a (sarcoplasmic reticulum Ca(2+)-ATPase, determined by test kits) decreased after 30-min ischemia, and intravenous F(2) in rats could ameliorate the decreased activity of SERCA2a. The inward and outward currents of NCX (recorded by whole-cell patch-clamp analysis) were reduced during 10-min hypoxia, and F(2) further inhibited the outward currents of NCX during 10-min hypoxia. All these data of SERCA2a and NCX might be responsible for the changes in calcium transients during hypoxia.

CONCLUSION

Our data suggest that F(2) reduced changes in calcium transients that caused by hypoxia/ischemia, which was regarded to be a protective role in calcium homeostasis of ventricular myocytes, probably via changing the function of SERCA2a.

Cardiac electrophysiological and antiarrhythmic effects of N-n-butyl haloperidol iodide

AIMS

N-n-butyl haloperidol (F(2)), a novel compound of quaternary ammonium salt derivatives of haloperidol, was reported to antagonize myocardial ischemia/reperfusion injuries. The antiarrhythmic potential and electrophysiological effects of F(2) on rat cardiac tissues were investigated.

METHODS AND RESULTS

In Langendorff-perfused rat hearts, the ventricular arrhythmias were induced by left anterior descending coronary artery of rat heart ligated for 20 min before the release of the ligature. F(2) provided some inhibitive effects against ischemia- and reperfusion-induced ventricular arrhythmias. In His bundle electrogram and epicardial ECG recordings, the drug produced bradycardia, delayed the conduction through the atrioventricular node and prolonged the Wenckebach cycle length and atrioventricular nodal effective refractory period. In whole-cell patch-clamp study, F(2) primarily inhibited the L-type Ca2+ current (I(Ca,L)) (IC(50) = 0.17 microM) with tonic blocking properties and little use-dependence. And the drug also decreased the Na+ current (IC(50) = 77.5 microM), the transient outward K+ current (IC(50) = 20.4 microM), the steady-state outward K+ current (IC(50) = 56.2 microM) and the inward rectifier K+ current (IC(50) = 127.3 microM).

CONCLUSION

F(2) may be a promising drug for the treatment of ischemic heart disease with cardiac arrhythmia.

Egr-1, a central and unifying role in cardioprotection from ischemia-reperfusion injury?

AIMS

Our previous studies have shown that N-n-butyl haloperidol iodide (F(2)) can antagonize myocardial ischemia/reperfusion (I/R) injury by blocking intracellular Ca(2+) overload and suppressing Egr-1 overexpression. The present study is to investigate the relation between the reduction of Ca(2+) overload and the inhibition of Egr-1 overexpression.

METHODS

The Sprague-Dawley rat myocardial I/R model and cultured cardiomyocyte hypoxia-reoxygenation (H/R) model were established. Administration of Egr-1 antisense oligodeoxyribonucleotide (AS-ODN) only or combining with F(2), Egr-1 protein expression was examined by Western-blot analyses. Hemodynamic parameters, creatine kinase (CK) and lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA), myeloperoxidase (MPO), cardiac troponin I (cTnI), and tumor necrosis factor-alpha (TNF-alpha) were measured to assess the degree of injury and inflammation of myocardial tissues and cells.

RESULTS

Treatment with Egr-1 AS-ODN significantly reduced Egr-1 protein expression and attenuated injury and inflammation of myocardium caused by I/R or H/R evidenced by the amelioration of hemodynamics, the decrease in leakage of CK, LDH, cTnI, the increase in MDA generation, the decrease in SOD activity, the reduction of MPO activity in myocardial tissues and release of TNF-alpha from cultured cardiomyocytes. Treatment with F(2) combined with Egr-1 AS-ODN, the inhibition of Egr-1 protein expression and inflammation (MPO activity and TNF-alpha level) were not enhanced, but the protection from myocardial I/R (or H/R) injury was significantly increased in hemodynamics and cytomembrane permeability relative to the using of Egr-1 AS-ODN only.

CONCLUSION

These data suggest that the inhibition of Egr-1 overexpression cannot involve all mechanisms of cardioprotection from I/R injury.

Reformative cannula electrodes for His bundle electrogram recording in isolated rat hearts

His bundle electrogram (HBE) recording is an important method for the study of the atrioventricular conduction system. However, the current HBE recording methods in isolated animal hearts have some disadvantages, such as unstable recording due to the difficulty in fixing electrodes as a result of intense heart beat, the small amplitude of the His signal or the possibility to destroy the integrity of heart structure. To overcome these disadvantages, we designed and manufactured reliable, inexpensive and easy-made bipolar cannula electrodes, which combine the functions of Langendorff-perfusion aortic cannula and recording electrodes. With the cannula electrodes, the operation of HBE recording becomes easier and clearer; hence, more stable recordings can be obtained in isolated rat hearts.

Protective effects of N-n-butyl haloperidol iodide on myocardial ischemia-reperfusion injury in rabbits

N-n-butyl haloperidol iodide (F2), a novel compound derived from haloperidol, was synthesized by our drugs research lab. The present study aims to evaluate the protective effects of F2 on myocardial ischemia-reperfusion injury in vivo, and to try to find the protective mechanism of F2. The animal model of myocardial ischemia-reperfusion injury was established by ligaturing rabbit's left ventricular branch of coronary artery for 40 min and removing the ligation later to reperfuse for 40 min. Different doses of F2 were intravenously injected before the onset of ischemia. The changes of hemodynamics were recorded during the experiment, and the activities of superoxide dismutase (SOD), creatine kinase (CK), Ca2+-ATPase, Na+,K+-ATPase and the level of malondialdehyde (MDA) of myocardial tissue were detected after reperfusion. Administration of F2 could dose-dependently ameliorate the hemodynamics of ischemia-reperfusion injured myocardium. During the course of reperfusion, MAP, LVSP, +/-dP/dt(max) in all F2 groups were obviously higher than those in the ischemia-reperfusion control group, and LVEDP were lower. F2 could also reduce the production of MDA, and maintain the activities of SOD, Ca2+-ATPase, Na+,K+-ATPase, and minimize the leakage of CK out of myocardial cells in a dose-dependent manner. These results suggested that F2 had apparent protective effects against myocardial ischemia-reperfusion injury.

Theory and laboratory study of a tall passive chamber for measuring gas fluxes at soil surface

A tall passive flux chamber with a height significantly greater than its horizontal dimensions is proposed for measuring fluxes of volatile organic compounds (VOCs) at the soil surface. The main feature of this tall chamber is the presence of a vertical concentration gradient of the target gas in the chamber. The emission and transport behavior of the target gas in the soil-chamber system are analyzed using the diffusion theory. A mathematical model is developed to estimate the flux from the soil into the tall chamber, providing the target gas establishes a detectable vertical concentration gradient in the chamber. To obtain the data required for calculating flux, only two gas concentrations (C1 and C2) at two heights (h1 and h2) within the chamber need to be measured at the end of a short chamber placement time (tp). To evaluate the applicability of the tall chamber for measuring flux, several laboratory tests have been conducted, using CH2Cl2 and CH3Br as the target gases. The results indicate that the proposed tall chamber has promising potential as a method for measuring fluxes of VOCs at the soil surface.