Catalytic performance and mechanism study of the isomerization of 2,5-dichlorotoluene to 2,4-dichlorotoluene.

This work investigates the influence of catalyst HZSM-5 on the isomerization of 2,5-dichlorotoluene (2,5-DCT) to produce 2,4-dichlorotoluene (2,4-DCT). We observe that hydrothermal treatment leads to a decrease in total acidity and Brønsted/Lewis ratio of HZSM-5 while generating new secondary pores. These characteristics result in excellent selectivity for post-hydrothermal modified HZSM-5 in the isomerization reaction from 2,5-DCT to 2,4-DCT. Under atmospheric pressure at 350 °C, unmodified HZSM-5 achieves a selectivity of 66.4% for producing 2,4-DCT, however after hydrothermal modification the selectivity increases to 78.7%. Density Functional Theory (DFT) calculations explore the thermodynamic aspects of adsorption between the HZSM-5 surface and 2,4-DCT. The kinetic perspective investigates the mechanism involving proton attack on the methyl group of 2,5-DCT followed by rearrangement leading to formation of 2,4-DCT during isomerization. The consistency between simulation and experimental results provides evidence for the feasibility of isomerizing 2,5-DCT to 2,4-DCT. This work fills the gap in the low value-added product 2,5-DCT isomer conversion, indicating its significant practical application potential and provides a valuable reference and guidelines for industrial research in this field.

Characterization of AST-001 non-clinical pharmacokinetics: A novel selective AKR1C3-activated prodrug in mice, rats, and cynomolgus monkeys.

AST-001 is a chemically synthesized inactive nitrogen mustard prodrug that is selectively cleaved to a cytotoxic aziridine (AST-2660) via aldo-keto reductase family 1 member C3 (AKR1C3). The purpose of this study was to investigate the pharmacokinetics and tissue distribution of the prodrug, AST-001, and its active metabolite, AST-2660, in mice, rats, and monkeys. After single and once daily intravenous bolus doses of 1.5, 4.5, and 13.5 mg/kg AST-001 to Sprague-Dawley rats and once daily 1 h intravenous infusions of 0.5, 1.5, and 4.5 mg/kg AST-001 to cynomolgus monkeys, AST-001 exhibited dose-dependent pharmacokinetics and reached peak plasma levels at the end of the infusion. No significant accumulation and gender differences were observed after 7 days of repeated dosing. In rats, the half-life of AST-001 was dose independent and ranged from 4.89 to 5.75 h. In cynomolgus monkeys, the half-life of AST-001 was from 1.66 to 5.56 h and increased with dose. In tissue distribution studies conducted in Sprague-Dawley rats and in liver cancer PDX models in female athymic nude mice implanted with LI6643 or LI6280 HepG2-GFP tumor fragments, AST-001 was extensively distributed to selected tissues. Following a single intravenous dose, AST-001 was not excreted primarily as the prodrug, AST-001 or the metabolite AST-2660 in the urine, feces, and bile. A comprehensive analysis of the preclinical data and inter-species allometric scaling were used to estimate the pharmacokinetic parameters of AST-001 in humans and led to the recommendation of a starting dose of 5 mg/m2 in the first-in-human dose escalation study.

Multi-network granular hydrogel with enhanced strength for 3D bioprinting.

Granular hydrogels are a kind of bulk hydrogel that are densely assembled by microparticles, showing great potential in 3D bioprinting. To develop a granular hydrogel-based bioink with enhanced strength, the present study combined methacryloylated gelatin (GelMA) with granular hydrogel to fabricate a compound bioink. Poly (γ-glutamic acid) (PG) microspheres and hydroxy propyl chitosan (CSPO) microspheres were fabricated, respectively, and self-assembled via charge interaction between microspheres to form a granular hydrogel after adding GleMA solution. However, its assembly ability decreased with the increase of the content of CSPO microspheres. The composite granular hydrogel with same mass content of PG microspheres and CSPO microspheres showed superior storage modulus, shear-thinning and self-healing ability. The composite granular hydrogels carrying adiposed derived stem cells (ASCs) showed well-performed extrudability and fidelity. In addition, after printing, UV light was used for further cross-linking GelMA, forming multi-networks that significantly improve the strength of the printed engineered tissue. ASCs proliferated significantly in bioink. The composite granular hydrogel thus showed great potential as bioink with enhanced strength for cell printing.

Uncovering the Pathogenesis of Orofacial Clefts Using Bioinformatics Analysis.

OBJECTIVE: Many genes have been found to be associated with the occurrence of the orofacial clefts (OFC). The links between these pathogenic genes are rarely studied. In this study, bioinformatics analysis were performed in order to find associations between OFC- related genes and provide new ideas for etiology study of OFCs. METHODS: Orofacial clefts-related genes were searched and identified from the Online Mendelian Inheritance of Man (OMIM.org). These genes were then analyzed by bioinformatics methods, including protein-protein interaction network, functional enrichment analysis, module analysis, and hub genes analysis. RESULTS: After searching the database of OMIM.org and removing duplicate results, 279 genes were finally obtained. These genes were involved to 369 pathways in biological process, 56 in cell component, 64 in molecular function, and 45 in the Kyoto Encyclopedia of Genes and Genomes. Most identified genes were significantly enriched in embryonic appendage morphogenesis (29.17%), embryonic limb morphogenesis (6.06%), and limb development (4.33%) for biological process ( Fig. 5A ); ciliary tip (42.86%), MKS complex (28.57%), ciliary basal body (14.29%), and ciliary membrane (14.29%) for cell component. The top 10 hub genes were identified, including SHH, GLI2, PTCH1, SMAD4, FGFR1, BMP4, SOX9, SOX2, RUNX2 , and CDH1. CONCLUSIONS: Bioinformatics methods were used to analyze OFC- related genes in this study, including hub gene identifying and analysis, protein - protein interaction network construction, and functional enrichment analysis. Several potential mechanisms related to occurrence of OFCs were also discussed. These results may be helpful for further studies of the etiology of OFC.

SIRT1 Antagonizes Oxidative Stress in Diabetic Vascular Complication.

Diabetic mellitus (DM) is a significant public health concern worldwide with an increased incidence of morbidity and mortality, which is particularly due to the diabetic vascular complications. Several pivotal underlying mechanisms are associated with vascular complications, including hyperglycemia, mitochondrial dysfunction, inflammation, and most importantly, oxidative stress. Oxidative stress triggers defective angiogenesis, activates pro-inflammatory pathways and causes long-lasting epigenetic changes to facilitate the development of vascular complications. Therefore, therapeutic interventions targeting oxidative stress are promising to manage diabetic vascular complications. Sirtuin1 (SIRT1), a class III histone deacetylase belonging to the sirtuin family, plays critical roles in regulating metabolism and ageing-related pathological conditions, such as vascular diseases. Growing evidence has indicated that SIRT1 acts as a sensing regulator in response to oxidative stress and attenuates vascular dysfunction via cooperating with adenosine-monophosphate-activated protein kinase (AMPK) to activate antioxidant signals through various downstream effectors, including peroxisome proliferator-activated receptor-gamma co-activator 1 (PGC-1α), forkhead transcription factors (FOXOs), and peroxisome proliferative-activated receptor α (PPARα). In addition, SIRT1 interacts with hydrogen sulfide (H2S), regulates NADPH oxidase, endothelial NO synthase, and mechanistic target of rapamycin (mTOR) to suppress oxidative stress. Furthermore, mRNA expression of sirt1 is affected by microRNAs in DM. In the current review, we summarize recent advances illustrating the importance of SIRT1 in antagonizing oxidative stress. We also discuss whether modulation of SIRT1 can serve as a therapeutic strategy to treat diabetic vascular complications.

Assessing the impacts of signal coordination on the crash risks of various driving cohorts.

INTRODUCTION: Signal coordination has been wildly implemented on urban arterials to improve traffic efficiency. The impacts of signal coordination on traffic safety, however, are largely overlooked, particularly on crash propensities of driver-vehicle cohorts, which will vary due to changing traffic flow patterns. METHOD: The paper aims to compare crash risks of various driving cohorts (measured by relative crash involvement ratio) on arterials with and without signal coordination with quasi-induced exposure technique, which has been well developed in estimating crash risks for driver-vehicle characteristics (i.e., driver age, gender, and vehicle type). Michigan traffic crash data (2000-2014) are retrieved for the case study. RESULTS: The results indicate that: (a) when signal coordination is implemented, young, male drivers, and pickups are associated with more crash responsibilities; (b) crash propensities vary for different disaggregated situations, e.g., young drivers may experience the rapid increase in crash risks during the peak hours; and (c) more hazardous actions (e.g., failing to stop in assured clear distance) are witnessed for the high-risk driving cohorts on the coordinated arterials than non-coordinated ones. Conclusions and practical applications: The findings highlight the importance of safety impact analysis of signal coordination, and serve to guide the potential improvements of safety operation and management of signal coordinated arterials.

Microscopic evaluation of traffic safety at signal coordinated intersections: A before-after study.

OBJECTIVE: This research aims to evaluate the safety impacts of signal coordination on signalized intersections and provide a scientific basis to design and improve signal control and management from a traffic safety perspective. METHODS: A kernel regression model is adopted to evaluate the safety performance of intersections before and after implementing the signal coordination strategy. By using this statistical method, the authors identify the nonlinear relationship between crash frequency and the crash's spatial location and examine the discrepancy of crash spatial distributions between the coordination and noncoordination conditions at disaggregated levels, such as time of day and crash type. A case study is presented with the use of Michigan crash data (2003-2007). RESULTS: The study finds that the (1) crash distribution on arterials tends to be spatially disperse when the signal coordination is in operation and (2) crash frequency at the approaches of intersections is increased with the use of signal coordination under the following conditions: Nonpeak hours, rear-end and sideswipe crashes, intersections with low speed limits, and both injury and property damage-only crashes. CONCLUSION: Signal coordination poses safety concerns in addition to its operational benefits for intersections.

Effects of miR-218-1-3p on Cell Proliferation, Cycle, and Apoptosis of Non-small Cell Lung Cancer / 中国医科大学学报

Objective To investigate the effect of miR-218-1-3p on the proliferation,cycle,and apoptosis of A549 cells in non-small-cell lung cancer.Methods miR-218-1-3p was transfected into non-small cell lung cancer A549 cells by LipofectamineTM 2000 Reagent,and the expression of miR-218-3p was detected by real-time PC R.Invasion and migration were assayed using the Transwell method.The effect of miR-218-1-3p on the proliferation of A549 cells was assayed by the MTS method.Changes in the cell cycle and apoptosis of A549 cells transfected with miR-218-1-3p was detected by flow cytometry.Changes in indicators related to cell proliferation,cycle,and apoptosis were detected by fluorescence quantitative PCR.Results Compared to the control group,the cell proliferation of A549 cells was significantly inhibited (P ＜ 0.05) and the proportion of cells in the S and G2-M phases was significantly decreased when miR-218-1-3p was up-regulated.In addition,compared with the control group,the early apoptotic rate was significantly increased by up-regulating miR-218-1-3p.We further detected indicators related to cell proliferation,cycle,and apoptosis and found that CYCLIN-D1 and BCL-2 were significantly downregulated.Conclusion miR-218-1-3p may inhibit proliferation,induce cell cycle arrest,and promote cell apoptosis of non-small cell lung cancer A549 cells by regulating CYCLIN-D 1 and BCL-2.

A novel slow-releasing hydrogen sulfide donor, FW1256, exerts anti-inflammatory effects in mouse macrophages and in vivo.

Exogenous hydrogen sulfide (H2S) is known to exert anti-inflammatory effects both in macrophages and in animal models. In this study, we first showed that NaHS caused a concentration dependent reduction in TNFα and IL-6 secretion in LPS-stimulated RAW264.7 macrophages in the absence of cell death. Thereafter, we screened a series of novel slow H2S donors for similar activity. One such compound, FW1256, concentration dependently decreased TNFα, IL-6, PGE2 and NO generation in LPS-stimulated RAW264.7 macrophages and BMDMs. FW1256 also significantly reduced IL-1ß, COX-2 and iNOS mRNA and protein in LPS-stimulated RAW264.7 macrophages. Mechanistically, FW1256 decreased NFκB activation as evidenced by reduced cytosolic phospho-IκBα levels and reduced nuclear p65 levels in LPS-stimulated RAW264.7 macrophages treated with FW1256. Using a H2S fluorescent probe in FW1256-treated RAW264.7 macrophages, H2S release from FW1256 was apparent over a period of 24h in these cells. Moreover, the effect of FW1256 on TNFα and IL-6 by FW1256 in LPS-stimulated RAW264.7 macrophages was reversed by treatment with the H2S scavenger, vitamin B12a. FW1256 had no cytotoxic effect on LPS-stimulated RAW264.7 macrophages or BMDMs. In vivo, FW1256 administration also reduced IL-1ß, TNFα, nitrate/nitrite and PGE2 levels in LPS-treated mice. We show here a novel slow H2S-releasing compound that exerts anti-inflammatory effects in macrophages and in vivo. FW1256 may be a useful tool to study the biological effects of exogenous H2S and could also have future therapeutic value in inflammatory conditions.

Hydrogel-Forming Microneedle Arrays Allow Detection of Drugs and Glucose In Vivo: Potential for Use in Diagnosis and Therapeutic Drug Monitoring.

We describe, for the first time the use of hydrogel-forming microneedle (MN) arrays for minimally-invasive extraction and quantification of drug substances and glucose from skin in vitro and in vivo. MN prepared from aqueous blends of hydrolysed poly(methyl-vinylether-co-maleic anhydride) (11.1% w/w) and poly(ethyleneglycol) 10,000 daltons (5.6% w/w) and crosslinked by esterification swelled upon skin insertion by uptake of fluid. Post-removal, theophylline and caffeine were extracted from MN and determined using HPLC, with glucose quantified using a proprietary kit. In vitro studies using excised neonatal porcine skin bathed on the underside by physiologically-relevant analyte concentrations showed rapid (5 min) analyte uptake. For example, mean concentrations of 0.16 µg/mL and 0.85 µg/mL, respectively, were detected for the lowest (5 µg/mL) and highest (35 µg/mL) Franz cell concentrations of theophylline after 5 min insertion. A mean concentration of 0.10 µg/mL was obtained by extraction of MN inserted for 5 min into skin bathed with 5 µg/mL caffeine, while the mean concentration obtained by extraction of MN inserted into skin bathed with 15 µg/mL caffeine was 0.33 µg/mL. The mean detected glucose concentration after 5 min insertion into skin bathed with 4 mmol/L was 19.46 nmol/L. The highest theophylline concentration detected following extraction from a hydrogel-forming MN inserted for 1 h into the skin of a rat dosed orally with 10 mg/kg was of 0.363 µg/mL, whilst a maximum concentration of 0.063 µg/mL was detected following extraction from a MN inserted for 1 h into the skin of a rat dosed with 5 mg/kg theophylline. In human volunteers, the highest mean concentration of caffeine detected using MN was 91.31 µg/mL over the period from 1 to 2 h post-consumption of 100 mg Proplus® tablets. The highest mean blood glucose level was 7.89 nmol/L detected 1 h following ingestion of 75 g of glucose, while the highest mean glucose concentration extracted from MN was 4.29 nmol/L, detected after 3 hours skin insertion in human volunteers. Whilst not directly correlated, concentrations extracted from MN were clearly indicative of trends in blood in both rats and human volunteers. This work strongly illustrates the potential of hydrogel-forming MN in minimally-invasive patient monitoring and diagnosis. Further studies are now ongoing to reduce clinical insertion times and develop mathematical algorithms enabling determination of blood levels directly from MN measurements.

GYY4137 attenuates remodeling, preserves cardiac function and modulates the natriuretic peptide response to ischemia.

AIMS: Myocardial infarction followed by adverse left ventricular (LV) remodeling is the most frequent proximate cause of heart failure. Hydrogen sulfide (H2S) is an important endogenous modulator of diverse physiological and pathophysiological processes. Its role in post-ischemic ventricular remodeling and the associated neurohormonal responses has not been defined. Here, we aimed at evaluating whether the slow-releasing water-soluble H2S donor GYY4137 (GYY) exerts cardioprotective effects and modulates the neurohormonal response to cardiac ischemic injury. METHODS AND RESULTS: Treatment for 2 or 7 days with GYY (100 mg/Kg/48 h, IP) after acute myocardial infarction (MI) in rats preserved LV dimensions and function in vivo, compared to untreated infarcted (MI), placebo- and dl-propargylglycine- (PAG, an inhibitor of endogenous H2S synthesis) treated animals (n=9/group/time-point). LV dimensions and function in GYY-treated animals were comparable to healthy sham-operated rats. GYY-treated hearts had significantly less LV fibrosis than MI, placebo and PAG hearts. A higher density of blood vessels was found in the LV scar area of GYY-treated animals compared to all other infarcted groups. Despite preserved LV structure and function, treatment with GYY increased the levels of the natriuretic peptides ANP and BNP in association with enhanced cyclic GMP levels, paralleled by higher cGMP-dependent protein kinase type I (cGKI) protein levels. CONCLUSIONS: Our data suggest that the slow-releasing H2S donor, GYY4137, preserves cardiac function, attenuates adverse remodeling and may exert post-ischemic cardioprotective (pro-angiogenic, anti-apoptotic, anti-hypertrophic and anti-fibrotic) effects in part through enhanced early post-ischemic endogenous natriuretic peptide activation.

Hydrogen sulfide promotes adipogenesis in 3T3L1 cells.

The effect of hydrogen sulfide (H2S) on differentiation of 3T3L1-derived adipocytes was examined. Endogenous H2S was increased after 3T3L1 differentiation. The expression of the H2S-synthesising enzymes, cystathionine γ-lyase (CSE), cystathionine ß-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST), was increased in a time-dependent manner during 3T3L1 differentiation. Expression of genes associated with adipogenesis related genes including fatty acid binding protein 4 (FABP4/aP2), a key regulator of this process, was increased by GYY4137 (a slow-releasing H2S donor compound) and sodium hydrosulfide (NaHS, a classical H2S donor) but not by ZYJ1122 or time-expired NaHS. Furthermore expression of these genes were reduced by aminooxyacetic acid (AOAA, CBS inhibitor), DL-propargylglycine (PAG, CSE inhibitor) as well as by CSE small interference RNA (siCSE) and siCBS. The size and number of lipid droplets in mature adipocytes was significantly increased by both GYY4137 and NaHS, which also impaired the ability of CL316,243 (ß3-agonist) to promote lipolysis in these cells. In contrast, AOAA and PAG had the opposite effect. Taken together, we show that the H2S-synthesising enzymes CBS, CSE and 3-MST are endogenously expressed during adipogenesis and that both endogenous and exogenous H2S modulate adipogenesis and adipocyte maturation.

Application of sub-Doppler DAVLL to laser frequency stabilization in atomic cesium.

We achieve laser frequency stabilization by a simple technique based on sub-Doppler dichroic atomic vapor laser lock (DAVLL) in atomic cesium. The technique that combines saturated-absorption spectroscopy and Zeeman splitting of hyperfine structures allows us to obtain a modulation-free dispersion-like error signal for frequency stabilization. For the error signal, the dependence of peak-to-peak amplitude and the slope at the zero-crossing point on the magnetic field is studied by simulation and experiment. Based on the result, we obtain an available sub-Doppler DAVLL error signal with high sensitivity to the frequency drift by selecting an appropriate strength of the magnetic field. Ultimately, the fluctuation of the locked laser frequency is confined to below 0.5 MHz in a long term, exhibiting efficient suppression of frequency noise.

Effect of feeding a high fat diet on hydrogen sulfide (H2S) metabolism in the mouse.

Hydrogen sulfide (H2S) has complex effects in inflammation with both pro- and anti-inflammatory actions of this gas reported. Recent work suggests that a deficiency of H2S occurs in, and may contribute to, the chronic inflammation which underpins ongoing atherosclerotic disease. However, whether a high fat diet, predisposing to atherosclerosis, affects H2S metabolism is not known. In this study we assessed H2S metabolism in different tissues of mice fed a high fat diet for up to 16 weeks. Ex vivo biosynthesis of H2S was reduced in liver, kidney and lung of high fat fed mice. Western blotting revealed deficiency of cystathionine γ lyase (CSE) in liver and lung with increased expression of cystathionine ß synthetase (CBS) in liver and kidney. Expression of 3-mercaptopyruvate sulfurtransferase (3-MST) was reduced in liver but not other tissues. Aortic endothelial cell CSE was also reduced in high fat fed animals as determined immunohistochemically. Plasma H2S concentration was not changed in these animals. No evidence of lipid deposition was apparent in aortae from high fat fed animals and plasma serum amyloid A (SAA) and C-reactive protein (CRP) were also unchanged suggesting lack of frank atherosclerotic disease. Plasma IL-6, IL12p40 and G-CSF levels were increased by high fat feeding whilst other cytokines including IL-1α, IL-1b and TNF-α were not altered. These results suggest that deficiency of tissue CSE and H2S occurs in mice fed a high fat diet and that this change takes place prior to development of frank atherosclerotic disease.

Hydrogen sulfide is an endogenous regulator of aging in Caenorhabditis elegans.

AIMS: To investigate the role of endogenous hydrogen sulfide (H2S) in the control of aging and healthspan of Caenorhabditis elegans. RESULTS: We show that the model organism, C. elegans, synthesizes H2S. Three H2S-synthesizing enzymes are present in C. elegans, namely cystathionine γ lyase (CSE), cystathionine ß synthetase, and 3-mercaptopyruvate transferase (MPST or 3-MST). Genetic deficiency of mpst-1 (3-MST orthologue 1), but not cth-2 (CSE orthologue), reduced the lifespan of C. elegans. This effect was reversed by a pharmacological H2S donor (GYY4137). GYY4137 also reduced detrimental age-dependent changes in a range of physiological indices, including pharyngeal contraction and defecation. Treatment of C. elegans with GYY4137 increased the expression of several age-related, stress response, and antioxidant genes, whereas MitoSOX Red fluorescence, indicative of reactive oxygen species generation, was increased in mpst-1 knockouts and decreased by GYY4137 treatment. GYY4137 additionally increased the lifespan in short-lived mev-1 mutants with elevated oxidative stress and protected wild-type C. elegans against paraquat poisoning. The lifespan-prolonging and health-promoting effects of H2S in C. elegans are likely due to the antioxidant action of this highly cell-permeable gas. INNOVATION: The possibility that novel pharmacological agents based on the principle of H2S donation may be able to retard the onset of age-related disease by slowing the aging process warrants further study. CONCLUSION: Our results show that H2S is an endogenous regulator of oxidative damage, metabolism, and aging in C. elegans and provide new insight into the mechanisms, which control aging in this model organism.

The hydrogen sulfide donor, GYY4137, exhibits anti-atherosclerotic activity in high fat fed apolipoprotein E(-/-) mice.

BACKGROUND AND PURPOSE: Atherosclerosis is associated with reduced vascular hydrogen sulfide (H2 S) biosynthesis. GYY4137 is a novel slow-releasing H2 S compound that may effectively mimic the time course of H2 S release in vivo. However, it is not known whether GYY4137 affects atherosclerosis. EXPERIMENTAL APPROACH: RAW 264.7 cells and human blood monocyte-derived macrophages were incubated with oxidized low density lipoprotein (ox-LDL) with/without GYY4137. ApoE(-/-) mice were fed a high-fat diet for 4 weeks and administered GYY4137 for 30 days. Lipid and atherosclerotic lesions were measured by oil red O staining. Endothelium-dependent relaxation was assessed in response to acetylcholine. Superoxide production was detected by dihydroethidium staining. Expression of mRNA and protein were evaluated by quantitative real-time PCR and Western blot. KEY RESULTS: GYY4137 inhibited ox-LDL-induced foam cell formation and cholesterol esterification in cultured cells. GYY4137 decreased the expression of lectin-like ox-LDL receptor-1, iNOS, phosphorylated IκBα, NF-κB, ICAM-1, VCAM-1 and chemokines, including CXCL2, CXCR4, CXCL10 and CCL17, but increased the scavenger protein CD36, in ox-LDL-treated RAW 264.7 cells. In vivo, GYY4137 decreased aortic atherosclerotic plaque formation and partially restored aortic endothelium-dependent relaxation in apoE(-/-) mice. GYY4137 decreased ICAM-1, TNF-α and IL-6 mRNA expression as well as superoxide (O2 (-) ) generation in aorta. In addition, GYY4137 increased aortic eNOS phosphorylation and expression of PI3K, enhanced Akt Ser(473) phosphorylation and down-regulated the expression of LOX-1. CONCLUSION AND IMPLICATIONS: GYY4137 inhibits lipid accumulation induced by ox-LDL in RAW 264.7 cells. In vivo, GYY4137 decreased vascular inflammation and oxidative stress, improved endothelial function and reduced atherosclerotic plaque formation in apoE(-/-) mice.

Senegalin: a novel antimicrobial/myotropic hexadecapeptide from the skin secretion of the African running frog, Kassina senegalensis.

Amphibian skin is a rich and unique source of novel bioactive peptides most of which are endowed with either antimicrobial or pharmacological properties. Here, we report the identification and structural characterization of a novel peptide, named senegalin, which possesses both activities. Senegalin is a hexadecapeptide amide (FLPFLIPALTSLISSL-NH2) of unique primary structure found in the skin secretion of the African running frog, Kassina senegalensis. The structure of the biosynthetic precursor of senegalin, deduced from cloned skin cDNA, consists of 76 amino acid residues and displays the typical domain organization of an amphibian skin peptide precursor. Both natural senegalin and its synthetic replicate displayed antimicrobial and myotropic activities. Senegalin was active against Staphylococcus aureus (MIC 50 µM) and Candida albicans (MIC 150 µM) but was non-haemolytic at concentrations up to and including 150 µM. In contrast, senegalin induced a dose-dependent contraction of rat urinary bladder smooth muscle (EC50 2.9 nM) and a dose-dependent relaxation of rat tail artery smooth muscle (EC50 37.7 nM). Senegalin thus represents a prototype biologically active amphibian skin peptide and illustrates the fact that amphibian skin secretion peptidomes continue to be unique sources of such molecules.

Aspirin regulates SNARE protein expression and phagocytosis in dendritic cells.

Since being introduced globally as Aspirin in 1899, acetylsalicylic acid (ASA) has been widely used as an analgesic, immune-regulatory, anti-pyretic and anti-thrombotic drug. ASA and its metabolite, salicylate, were also reported to be able to modulate antigen presenting functions of dendritic cells (DC). However, the intracellular targets of ASA in DC are still poorly understood. Since phagocytosis is the initial step taken by antigen-presenting cells in the uptake of antigens for processing and presentation, ASA might exerts its immune-regulatory effects by regulating phagocytosis. Here we show that ASA inhibits phagocytosis and modulates expression of endosomal SNAREs, such as Vti1a, Vti1b, VAMP-3, VAMP-8 and Syn-8 (but not syn-6 and syn-16) in DC. We further show that the phagocytic inhibitory effect of ASA is dependent on the expression of Vti1a and Vti1b. Consistently, Vti1a and Vti1b localize to the phagosomes and up-regulation of Vti1a and Vti1b inhibits phagocytosis in DC. Our results suggest that ASA modulates phagocytosis in part through the control of endosomal SNARE protein expression and localization in DC. All experiments were performed using either a murine DC line (DC2.4) or primary DC derived from murine bone marrow cells.