Anthrax Lethal Toxin Suppresses Murine Cardiomyocyte Contractile Function and Intracellular Ca2+ Handling via a NADPH Oxidase-Dependent Mechanism

OBJECTIVES: Anthrax infection is associated with devastating cardiovascular sequelae, suggesting unfavorable cardiovascular effects of toxins originated from Bacillus anthracis namely lethal and edema toxins. This study was designed to examine the direct effect of lethal toxins on cardiomyocyte contractile and intracellular Ca(2+) properties. METHODS: Murine cardiomyocyte contractile function and intracellular Ca(2+) handling were evaluated including peak shortening (PS), maximal velocity of shortening/ relengthening (± dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR(90)), intracellular Ca(2+) rise measured as fura-2 fluorescent intensity (ΔFFI), and intracellular Ca(2+) decay rate. Stress signaling and Ca(2+) regulatory proteins were assessed using Western blot analysis. RESULTS: In vitro exposure to a lethal toxin (0.05-50 nM) elicited a concentration-dependent depression on cardiomyocyte contractile and intracellular Ca(2+) properties (PS, ± dL/dt, ΔFFI), along with prolonged duration of contraction and intracellular Ca(2+) decay, the effects of which were nullified by the NADPH oxidase inhibitor apocynin. The lethal toxin significantly enhanced superoxide production and cell death, which were reversed by apocynin. In vivo lethal toxin exposure exerted similar time-dependent cardiomyocyte mechanical and intracellular Ca(2+) responses. Stress signaling cascades including MEK1/2, p38, ERK and JNK were unaffected by in vitro lethal toxins whereas they were significantly altered by in vivo lethal toxins. Ca(2+) regulatory proteins SERCA2a and phospholamban were also differentially regulated by in vitro and in vivo lethal toxins. Autophagy was drastically triggered although ER stress was minimally affected following lethal toxin exposure. CONCLUSIONS: Our findings indicate that lethal toxins directly compromised murine cardiomyocyte contractile function and intracellular Ca(2+) through a NADPH oxidase-dependent mechanism

Identification of molecular pathways affected by pterostilbene, a natural dimethylether analog of resveratrol

<p>Abstract</p> <p>Background</p> <p>Pterostilbene, a naturally occurring phenolic compound produced by agronomically important plant genera such as <it>Vitis </it>and <it>Vacciunium</it>, is a phytoalexin exhibiting potent antifungal activity. Additionally, recent studies have demonstrated several important pharmacological properties associated with pterostilbene. Despite this, a systematic study of the effects of pterostilbene on eukaryotic cells at the molecular level has not been previously reported. Thus, the aim of the present study was to identify the cellular pathways affected by pterostilbene by performing transcript profiling studies, employing the model yeast <it>Saccharomyces cerevisiae</it>.</p> <p>Methods</p> <p><it>S. cerevisiae </it>strain S288C was exposed to pterostilbene at the IC₅₀concentration (70 μM) for one generation (3 h). Transcript profiling experiments were performed on three biological replicate samples using the Affymetrix GeneChip Yeast Genome S98 Array. The data were analyzed using the statistical methods available in the GeneSifter microarray data analysis system. To validate the results, eleven differentially expressed genes were further examined by quantitative real-time RT-PCR, and <it>S. cerevisiae </it>mutant strains with deletions in these genes were analyzed for altered sensitivity to pterostilbene.</p> <p>Results</p> <p>Transcript profiling studies revealed that pterostilbene exposure significantly down-regulated the expression of genes involved in methionine metabolism, while the expression of genes involved in mitochondrial functions, drug detoxification, and transcription factor activity were significantly up-regulated. Additional analyses revealed that a large number of genes involved in lipid metabolism were also affected by pterostilbene treatment.</p> <p>Conclusion</p> <p>Using transcript profiling, we have identified the cellular pathways targeted by pterostilbene, an analog of resveratrol. The observed response in lipid metabolism genes is consistent with its known hypolipidemic properties, and the induction of mitochondrial genes is consistent with its demonstrated role in apoptosis in human cancer cell lines. Furthermore, our data show that pterostilbene has a significant effect on methionine metabolism, a previously unreported effect for this compound.</p

Multiple acute temperature stress affects leucocyte populations and antibody responses in common carp, Cyprinus carpio L

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Effects of Bifidobacterium Breve Feeding Strategy and Delivery Modes on Experimental Allergic Rhinitis Mice.

Different delivery modes may affect the susceptibility to allergic diseases. It is still unknown whether early intervention with probiotics would counteract this effect.The effect of different delivery modes on immune status and nasal symptoms was investigated on established allergic rhinitis (AR) mouse model. In addition, the immunoregulatory effects and mechanisms of different feeding manners with Bifidobacterium breve(B. breve) were examined.Live lyophilized B. breve was orally administered to BALB/c mice born via vaginal delivery(VD) or cesarean delivery (CD) for 8 consecutive weeks, after which they were sensitized by ovalbumin(OVA) to establish experimental AR. Nasal symptoms, serum immunoglobulins, cytokines, splenic percentages of CD4(+)CD25(+)Foxp3(+) regulatory T(Treg) cells and nasal eosinophil infiltration were evaluated.Compared with VD mice, mice delivered via CD demonstrated more serious nasal symptoms, higher concentrations of OVA-specific immunoglobulin (Ig) E, more nasal eosinophils and lower percentages of splenic CD4(+)CD25(+)Foxp3(+)Treg cells after establishing experimental AR. These parameters were reversed by administering B. breves hortly after birth. However, the effect of B. breve did not differ between different delivery modes.CD aggravates the nasal symptoms of AR mice compared to VD. This is the first report that oral administration of B. breve shortly after birth can significantly alleviate the symptoms of AR mice born via both deliveries, probably via activation of the regulatory capacity of CD4(+)CD25(+)Foxp3(+)Treg cells