Sinomenine inhibits primary CD4+ T-cell proliferation via apoptosis

Sinomenine is an active component isolated from Sinomenium acutum and is widely used as an immunosuppressive drug for treating autoimmune diseases. CD4(+) T-cell population plays a key role in adaptive immune response and is related to some autoimmune diseases. In this study, we investigated the possible immunosuppressive effect of sinomenine on CD4(+) T cells and its underlying mechanism. Our data demonstrated that sinomenine remarkably suppressed the proliferation of CD4(+) T cells, blocked the cell cycle progression from G0/G1 phase to S plusG2/M phases. Finally, the immunosuppressive activity elicited by sinomenine in CD4(+) primary lymphocytes was found to be largely accounted for by caspase 3-dependent cells apoptosis. Sinomenine did not significantly alter the expression of bcl-2 in activated CD4(+) primary T cells, suggesting that bcl-2 might not be involved in sinomenine-induced T cells apoptosis. In sum, this study proposes a novel mechanism for the immunosuppressive function of sinomenine on primary mouse CD4(+) T cells.     

Macromolecular transport in heart valves. I. Studies of rat valves with horseradish peroxidase

The present study aims to experimentally elucidate subtle structural features of the rat valve leaflet and the related nature of macromolecular transport across its endothelium and in its subendothelial space, information necessary to construct a rational theoretical model that can explain observation. After intravenous injection of horseradish peroxidase (HRP), we perfusion-fixed the aortic valve of normal Sprague-Dawley rats and found under light microscopy that HRP leaked through the leaflet's endothelium at very few localized brown spots, rather than uniformly. These spots grew nearly as rapidly with HRP circulation time before euthanasia as aortic spots, particularly when the time axis only included the time the valve was closed. These results suggest that macromolecular transport in heart valves depends not only on the direction normal to, but also parallel to, the endothelial surface and that convection, as well as molecular diffusion, plays an important role in macromolecular transport in heart valves. Transmission electron microscopy of traverse leaflet sections after 4-min HRP circulation showed a very thin ( approximately 150 nm), sparse layer immediately beneath the endothelium where the HRP concentration was much higher than that in the matrix below it. Nievelstein-Post et al.'s (Nievelstein-Post P, Mottino G, Fogelman A, Frank J. Arterioscler Thromb 14: 1151-1161, 1994) ultrarapid freezing/rotary shadow etching of the normal rabbit valve's subendothelial space supports the existence of this very thin, very sparse "valvular subendothelial intima," in analogy to the vascular subendothelial intima.     

Pharmacological and biophysical isolation of K+ currents encoded by ether-à-go-go-related genes in murine hepatic portal vein smooth muscle cells

The functional properties of the Saccharomyces cerevisiae bicarbonate transporter homolog Bor1p (YNL275wp) were characterized by measuring boron (H₃BO₃), Na⁺, and Cl^– fluxes. Neither Na⁺ nor Cl^– appears to be a transported substrate for Bor1p. Uphill efflux of boron mediated by Bor1p was demonstrated directly by loading cells with boron and resuspending in a low-boron medium. Cells with intact BOR1, but not the deletant strain, transport boron outward until the intracellular concentration is sevenfold lower than that in the medium. Boron efflux through Bor1p is a saturable function of intracellular boron (apparent K_m 1–2 mM). The extracellular pH dependences of boron distribution and efflux indicate that uphill efflux is driven by the inward H⁺ gradient. Addition of 30 mM HCO₃^– does not affect boron extrusion by Bor1p, indicating that HCO₃^– does not participate in Bor1p function. Functional Bor1p is present in cells grown in medium with no added boron, and overnight growth in 10 mM H₃BO₃ causes only a small increase in the levels of functional Bor1p and in BOR1 mRNA. The fact that Bor1p is expressed when there is no need for boron extrusion and is not strongly induced in the presence of growth-inhibitory boron concentrations is surprising if the main physiological function of yeast Bor1p is boron efflux. A possible role in vacuolar dynamics for Bor1p was recently reported by Decker and Wickner (10). Under the conditions used presently, there appears to be mildly abnormal vacuolar morphology in the deletant strain. boron; SLC4; YNL275w     

Two-component sensor RhpS promotes induction of Pseudomonas syringae type III secretion system by repressing negative regulator RhpR

The Pseudomonas syringae type III secretion system (T3SS) is induced during interaction with the plant or culture in minimal medium (MM). How the bacterium senses these environments to activate the T3SS is poorly understood. Here, we report the identification of a novel two-component system (TCS), RhpRS, that regulates the induction of P. syringae T3SS genes. The rhpR and rhpS genes are organized in an operon with rhpR encoding a putative TCS response regulator and rhpS encoding a putative biphasic sensor kinase. Transposon insertion in rhpS severely reduced the induction of P. syringae T3SS genes in the plant as well as in MM and significantly compromised the pathogenicity on host plants and hypersensitive response-inducing activity on nonhost plants. However, deletion of the rhpRS locus allowed the induction of T3SS genes to the same level as in the wild-type strain and the recovery of pathogenicity upon infiltration into plants. Overexpression of RhpR in the deltarhpRS deletion strain abolished the induction of T3SS genes. However, overexpression of RhpR in the wild-type strain or overexpression of RhpR(D70A), a mutant of the predicted phosphorylation site of RhpR, in the deltarhpRS deletion strain only slightly reduced the induction of T3SS genes. Based on these results, we propose that the phosphorylated RhpR represses the induction of T3SS genes and that RhpS reverses phosphorylation of RhpR under the T3SS-inducing conditions. Epistasis analysis indicated that rhpS and rhpR act upstream of hrpR to regulate T3SS genes.     

An off-line filtering ditch–pond system for diffuse pollution control at Wuhan City Zoo

An off-line filtering ditch–pond system was designed and constructed to control the small point and runoff pollution at the Wuhan City Zoo, Hubei Province, China. The quantity and quality of wastewater discharge and runoff from 16 rainfall events were measured to test the effectiveness of the off-line treatment train. The results showed that the water quality was improved and high retention rates for water and pollutants were also achieved by the off-line treatment train. In the outflows, the event mean concentrations (EMCs) of TSS, COD, TN, TDN, TP and TDP were reduced by 75%, 50%, 50%, 57%, 74% and 80% compared to the inflows. In 2005, the annual inflow volume in the catchment was 6783 m³ and the water retention rate was 80.1%. The retention rates in the annual loads of TSS, COD, TN and TP came to 86.4%, 85.5%, 83.9% and 82.9%, respectively. Therefore, the off-line filtering ditch–pond system was shown to be an effective and economical measure to control diffuse pollution. It would be worthwhile to extend the off-line treatment train to regions with limited land resources, especially in urban areas.     

Antiadhesive property of microalgal polysaccharide extract on the binding of Helicobacter pylori to gastric mucin

The emergence of antibiotic-resistant Helicobacter pylori is of concern in the treatment of H. pylori-associated gastroduodenal diseases. As the organism was reported to bind gastric mucin, we used porcine gastric mucin as substrate to assess the antiadhesive property of polysaccharides derived from Spirulina (PS), a commercially available microalga, against the binding of H. pylori to gastric mucin. Results show that polysaccharides prevented H. pylori from binding to gastric mucin optimally at pH 2.0, without affecting the viability of either bacteria or gastric epithelial cells, thus favouring its antiadhesive action in a gastric environment. Using ligand overlay analysis, polysaccharide was demonstrated to bind H. pylori alkyl hydroperoxide reductase (AhpC) and urease, which have shown here to possess mucin-binding activity. An in vivo study demonstrated that bacteria load was reduced by >90% in BALB/c mice treated with either Spirulina or polysaccharides. It is thus suggested that polysaccharides may function as a potential antiadhesive agent against H. pylori colonization of gastric mucin.     

Retrograde adaptive resonance theory based on the role of nitric oxide in long-term potentiation

Adaptive resonance theory (ART) demonstrates how the brain learns to recognize and categorize vast amounts of information by using top–down expectations and attentional focusing. ART 3, one member of the ART family, embeds the computational properties of the chemical synapse in its search process, but it converges slowly and is lack of stability when being applied in pattern recognition and analysis. To overcome these problems, Nitric Oxide (NO), which serves as a newly discovered retrograde messenger in Long-Term Potentiation (LTP), is introduced in retrograde adaptive resonance theory (ReART) model presented in this paper. In the presented model a novel search hypothesis is proposed to incorporate angle and amplitude information of an external input vector to decide whether the input matches the long-term memory (LTM) weights of an active node or not, and the embedded NO retrograde mechanism makes the search procedure a closed loop, which improves the stability and convergence speed of the transmitter releasing mechanism in a synapse. To make the model more adaptive and practical, a forgetting mechanism is built to improve the weights updating process. Experimental results indicate that the proposed ReART model achieves low error rate, fast convergence and self-organizing weights regulation. Action Editor: Christiane Linster     

Caspase-11 regulates cell migration by promoting Aip1-Cofilin-mediated actin depolymerization

Coordinated regulation of cell migration, cytokine maturation and apoptosis is critical in inflammatory responses. Caspases, a family of cysteine proteases, are known to regulate cytokine maturation and apoptosis. Here, we show that caspase-11, a mammalian pro-inflammatory caspase, regulates cell migration during inflammation. Caspase-11-deficient lymphocytes exhibit a cell-autonomous migration defect in vitro and in vivo. We demonstrate that caspase-11 interacts physically and functionally with actin interacting protein 1 (Aip1), an activator of cofilin-mediated actin depolymerization. The caspase-recruitment domain (CARD) of caspase-11 interacts with the carboxy-terminal WD40 propeller domain of Aip1 to promote cofilin-mediated actin depolymerization. Cells with Aip1 or caspase-11 deficiency exhibit defects in actin dynamics. Using in vitro actin depolymerization assays, we found that caspase-11 and Aip1 work cooperatively to promote cofilin-mediated actin depolymerization. These data demonstrate a novel cell autonomous caspase-mediated mechanism that regulates actin dynamics and mammalian cell migration distinct from the receptor mediated Rho-Rac-Cdc42 pathway.